摘要:

J . CHEM. SOC. DALTON TRANS. 1987 1805 Metallacarboranes derived from the [C2B,oH,2]2- Anion. The Preparation, Molecular Structure, and Properties of [4- (dppe)-4- Pd-1 ,6-C2B ,,H 12], [4,4,4-H( PPh3),-2-OMe-4-lr-1 ,6-C2Bl0H,,], and [3-(dppe)-3-Pt-1.2-C2B,H,,] t Nathaniel W. Alcock, John G. Taylor, and Malcolm G. H. Wallbridge Department of Chemistry, University of Warwick, Coventry CV4 7AL The action of Na,[C,B,,H,,] on [PdCl,(dppe)] (dppe = Ph,PCH,CH,PPh,) yields the 13- vertex yellow closo species [(dppe)PdC,B,,H,,] (1 ), and the reaction of "Me,] [C,B,,H,,] with [IrCI(PPh,),] in light petroleum-methanol gives a related 13-vertex cage of yellow [( PPh,),HIrC,B,,H,,(OMe)] (2), whose formation involves attack by a solvent molecule. The structure of both products have been established by X-ray diffraction [R = 0.039 and 0.074 for 4 786 and 4 130 diffractometer-measured observed reflections, for (1 ) and (2) respectively]. Both show the characteristic 1 : 5: 6: 1 structure for 13-vertex polyhedra, distorted by carbon substitution.The reaction of TI(0,CMe) with Na,[C,B,,H,,] in ethanol leads to degradation of the C,B,, cage, and yields an orange solid formulated as TI,(C,B,H,,)O. Treatment of this solid with [ PtCl,(dppe)] gives the pale orange [ (dppe) PtC,B,H,, J (3); it has an icosahedral structure [R = 0.068 for 3 530 observed reflections], distorted mainly by the lengthening of the Pt-C bonds in comparison to the Pt-B bonds. The study of metalla-borane and -carborane derivatives con- tinues to be an active area of research, and has recently been reviewed.' We are interested in the effects resulting from the insertion of electron-rich metals (e.g.those of Group 8 and subsequent groups) into carborane frameworks, since such species often show considerable distortions in the resulting metallacarborane.2 While such distortions are now well known for the 12-vertex MC2B9 systems, we were interested to see whether similar distortions would occur in 13-vertex MC2Blo cages. Such derivatives can be easily obtained by the reaction of a metal halide derivative with the borane or carborane anion, often as the alkali-metal salt. For example, the anion [C,B,oH,z]Z- can be obtained conveniently by the action of sodium in tetrahydrofuran (thf) on the icosahedral carborane t,2-CzBl,H,2.3 Although the structure of this anion is as yet unknown, several metalla-derivatives have been character- ised,'*4-5 although detailed structural data are only available for the titanium(w)6 and cobalt(ii1) ' derivatives (Scheme).Scheme. M = Ti, Zr, Hf, V, Cr, Mo. W, Mn, Fe,Co, or Ni; L = q-C,H, or KO), We now report the preparation, properties, and structures of derivatives containing the electron-rich Group 8 metals palladium and iridium, and also the results of attempts to prepare the thallium salt of [C2Bl,H,zJ2-. This salt is expected to be a useful precursor in the preparation of other metalla-derivatives, as is found for the corresponding salt TI2CC2B9H 1 I].* t 4-[ 1 ',2'-Bis(diphenylphosphino)ethane J-c.iuso-l.6-dicarba-4-pallada- tridecdborane, 4-hydrido-2-methoxo-4,4-bis(triphenylphosphine)- closo- 1.6-dicarba-4-iridatridecaborane, and 3-[ 1 '2'-bis(diphenyl- phosphino)et hane]-c.ioso- 1,2-dicarba-3-plat inadodecaborane, respec- tively. (The numbering system employed is as suggested in J.B. Casey, W. J. Evans, and W. H. Powell, Inorg. Chem., 1981, 20, 1333.) Suppicmenfury duiu uouiluble: see Instructions for Authors, J. Chem. Soc., Dulion Truns.. 1987, Issue 1, pp. xvii-xx. 10 0 -10 -20 4Vp.p.m. Figure 1. The 128-MHz "B-{'HJ n.m.r. spectrum of [(dppe)Pd- C2B, ,H 23 in dichloromethane Results and Discussion The addition of [PdCl,(dppe)] [dppe = 1,2-bis(diphenyI- phosphino)ethane] to a dichloromethane solution of Na,- [C,B,,H,,] gives an initial red colour. On filtration in air the solution slowly changes to a straw yellow colour, and yellow crystals of [(dppe)PdC,B,,H 2] (1) were obtained after purification.Colour changes have been observed previously in transition-metal derivatives of the [C2B, ,H ,I2 - ion, and have been ascribed to the facile interconversion of structural isomer^.^ Since it appears unlikely that this colour change is associated with oxidation of the metal ion, we assume that structural changes probably occur in this case also. The difficulty of assigning a plausible structure to the1806 J. CHEM. SOC. DALTON TRANS. 1987 Figure 2. Molecular structure of [(dppe)PdC2BloHl2], (1) showing the crystallographic atomic numbering. Hydrogen atoms are omitted for clarity here and elsewhere MC,B,, framework from n.m.r. data alone has been reported previo~sly,4*~ and (1) presents similar difficulties. The best resolved 'B-{ 'H) n.m.r.spectrum at 128 MHz showed a series of five broad overlapping resonances (Figure l), and the integration based on a fragment containing ten boron atoms is unclear. While the ratio of the four resonances between + 5 and - 10 p.p.m. to that near - 18 p.p.m. is approximately 8: 2 (actually 8.8 : 2), the individual ratios of the lower-field set of four resonances are approximately 1 : 3 : 2 : 1. Since this group of resonances apparently represents eight boron atoms we assume that the overlap of the resonances causes this anomaly. The resonances broaden considerably at lower temperatures, thus at -90 ' C in CH,CI, the resonance at - 1 p.p.m. is over 800 Hz wide at half-height. Fluxionality in such 13-vertex systems has been observed previ~usly,~ and has been reasonably suggested to arise from an interchange between isomeric species which have the carbon atoms of the C2B4 face in alternative positions, it being assumed that the interchange proceeds via the squarediamond-square process.Since we were unable to make any structural assignment from the n.m.r. data a crystal-structure determination was undertaken. The resulting structure (Figure 2) confirms the presence of a 13-vertex metallacarborane cioso cluster, and shows that the two carbon atoms are separated by a boron atom in the six- membered C,B, face; this feature is similar to that observed previously in [NMe,],[Ti(C,B,,H IoMe,),J and [(q-C5H5)- CO(C,B,,H,,)].~ While there is no strong distortion of the fragment containing the d8 Pd" and the C,B, face, some asymmetry is evident (see below).A related yellow iridium derivative, [( PPh,),HIrC,B, ,H I - (OMe)] (2) was prepared by refluxing [IrCI(PPh,),] and [NMe4][C,Bl,H,,] in light petroleum (b.p. 60-80 "C)- methanol. Refluxing the two reagents for 1 h in light petroleum alone produced no colour change. The I ' B n.m.r. spectrum (CH,CI, solution) showed a series of broad overlapping resonances (at least three in number) between + 17 and + 2 p.p.m., and as with (1) was unhelpful for structural assignment. A crystal-structure determination (Figure 3) revealed that an unexpected solvolysis had taken place replacing one cage B-H hydrogen by -OMe, and that (2) is the 13-vertex doso species [(PPh,),HIrC2BloHI ,(OMe)J.As with (1) the two carbon atoms are separated by a boron atom; further structural details are discussed below. The presence of the methoxy group is Figure 3. Molecular structure of [(PPh,),HIrC,B,,H, ,(OMe)] (2) showing the crystallographic atomic numbering perhaps not too surprising since other examples are known where methoxy groups are substituted into metallaboranes when the compounds are formed in alcoholic solution.' Predictably the methoxy group substitutes at the boron atom which adjoins the two carbon atoms and the metal atom. We have also attempted to prepare the thallium derivative TI, [C, B ,H , J by reacting Na, [C,B , ,H , J with thallium( I) acetate, since it is known that a similar reaction using Na2[C2B,H, '3 yields TI,[C2B,H, 3.' In the present work the interaction of an ethanol solution of thallium(1) acetate with Na,[C,B,,H, ,] in thf produced a flocculent orange precipitate. The material appeared to be heat sensitive, since attempts to coagulate the suspension by heating caused some darkening.Although the heating was carried out in the light, we have observed that the precipitate is not light sensitive, at least over a few hours. However, the precipitate could be filtered off, and after drying under vacuum yielded an orange solid. No satis- factory n.m.r. spectra could be obtained from the solid due to insolubility, but elemental analysis was not consistent with the formulation TI,[C2Bl,H12]. In view of the analytical data, and the reactions described below, it appears that a cage degradation has occurred, and the best formulation we can propose for the solid is TI,(C,B,H 2)0.When the orange solid is suspended in thf, and treated with [PMePh,]Br, the mixture slowly darkens and a black solid is precipitated. A pale yellow solid can be recovered in high yield from the supernatant after filtration, and this solid corresponds to [PMePh,][C,B,H,,] from analytical data and the "B n.m.r. spectrum. The latter shows doublets at -9.44 (relative intensity 2), - 15.2 (2), - 16.2 (l), -20.8 (2), -31.6 (I), and -36.4 (1) p.p.m.; these values are very similar to those for [C2B,H ,] - reported previously.' The i.r. spectrum of the solid shows the expected absorptions from the cation, but also gives a broad band at 2 500 cm-I whose contour is similar to that reported for the [C2B,H12]- ion." We assume that the black solid produced is T1,0, and that the overall reaction proceeds as follows.TI,(C,B,H,,)O + [PMePh,]Br - [PMePh,][C,B,H,,] + T1,O + TlBr The base degradation of C2B,,H1, to [C2B,HI2]- occurs readily when the former is treated with an NaOEt-EtOHJ. CHEM. SOC. DALTON TRANS. 1987 1807 Figure 4. Molecular structure of [(dppe)PtC2B,H, J (3) showing the crystallographic atomic numbering mixture." I n the present work the acetate ion appears to have the same effect as alkoxide, and indeed we have confirmed that even an Li(0,CMe)-EtOH mixture carries out this degrad- ation. The alternative pathways involving the formation and decomposition of an intermediate 13-vertex metallacarborane appear less likely, though such a route has been proposed to explain the formation of [(q-C5HS)Co(C,B,H, ])] from the direct action of [Co(CO),(q-C,H,)] on C2B,oH,2.1r The presence of a C2B9 fragment in the orange thallium derivative is also indicated by its interaction with [PtCI,- (dppe)].The yellow-orange complex [(dppe)PtC,B,H (3) was isolated from the reaction mixture, and tentatively identi- fied from its I l B n.m.r. spectrum by comparison with those previously reported for similar PtC,B9 cage compounds which have the two carbon atoms occupying adjacent positions in the cage.,.' ' However, since the spectrum shows broad overlapping resonances [ + 10.1 (relative intensity l), - 10.3 ( 9 , and -21.5 (3)], an X-ray structure determination was undertaken to confirm this identification (Figure 4).Siructurcil Resu1r.y.-While the 13-vertex MC2Bl0 polyhedra in ( 1 ) and (2) are necessarily rather irregular, they share the same overall geometry, which is also common to the two pre- vious 13-vertex structures rep~rted.~.' This can best be seen from a diagram of connectivity and distances (Figure 5; cj: Figure 3 in ref. 7), which shows the overall pseudo-mirror symmetry of the polyhedra.6 However, there are interesting differences between both (1) and (2), and the well defined cobalt compound. Despite the different metal electron configurations in (1) ( d 8 ) and (2) ( d 6 ) there are some similarities in the pattern of M-cage bonds (Figure 6 and Table 1). Each has the shortest link to the unique low-co-ordinate carbon atom [C(l)], and both have a significantly longer bond to an atom one away from this unique carbon.I n (1) this link is to the other carbon [Pd-C(6)], while in (2) it is to a boron atom [Ir-B(7)]; the remaining facial bonds are relatively short. This indicates both that the top C,B, layers of the cages are similar in their distortions, and that the metal atoms are attached in very much the same position relative to the centroid of the open face. In contrast, in the cobalt compound, although the Co-C(unique) bond is still the shortest, all the other M-facial bond lengths are comparable. The compounds (1) and (2) do show a significant difference because of the presence of the hydride ligand on Ir. In (I), the P( 1 )-Pd-P( 2) plane is almost perpendicular to the mean 12 1 Figure 5. Schematic representations of the carborane fragments in com- pounds (1) and (2).The atom numbers relate to boron unless otherwise indicated, bond distances in A Figure 6. Schematic representation of of the M-cage bonding in com- pounds ( I ) , (2), and [(q-C5H5)Co(C2Bl,H,2)], bond distances in A1808 J. CHEM. SOC. DALTON TRANS. 1987 Table I. Principal bond lengths (A) and angles (") for compounds (I), (2), and (3) Compound (1) Pd-P( 1 ) Pd-P(2) Pd-B( 2) Pd-B( 3) Pd-B(7) Pd-B( 10) Pd-C(6) B(2)-c( 1) Pd-C( 1 ) Compound (2) Ir-P( 1) Ir-P(2) Ir-B(2) Ir-C( 1) Ir-B(3) Ir-B(7) Ir-B( 10) Ir-C(6) B(2)-C(6) B(2)-C( 1 ) Compound (3) Pt-P( 1) Pt-P(2) Pt-C( 2) Pt-C(3) Pt-B(4) Pt-B(5) Pt-B( 6) C( 21-a 3 1 2.3 17( 1) 2.252( 1) 2.387(5) 2.187( 5 ) 2.455( 5 ) 2.252(6) 2.300( 4) 2.609(4) 1.546(7) 2.340(5) 2.3 12(4) 2.305( 18) 2.230( 16) 2.350( 25) 2.520( 15) 2.3 36( 22) 2.360( 15) 1.69(3) 1.50(3) 2.266( 3) 2.259(3) 2.502( 3) 2.505(3) 2.251 (3) 2.279(3) 2.255(3) 1.53(3) B-M-P angles (1) Smallest to P( 1) 97.4( 1 ) from B(2) Smallest to F(2) 89.8(1) from B(7) 1.674(6) 1.912(7) 2.173(7) 1.5 12(8) 1.746( 8) 1.865(7) 1.91 l(7) 1.767(7) 1.862(6) 1.97(3) 2.33(3) 1.43(2) 1.44(3) 1.62(3) 1.80(3) 1.99( 3) 1.90(3) I .72( 3) 1.74(3) 1.71(3) 1.63(3) I .79(3) 1.67(3) 1.76(3) 1.83(3) 1.81(3) 1.769(7) 1.760(7) 1.669(7) 1.800( 8) 1.816(7) 1.677(7) 1.666( 7) 1.737(8) 1.754(6) 1.62(3) 1.84(3) I .79(3) 1.84( 3) 1.74( 3) 1.82(3) 1.79(3) 1.72(3) 1.79(3) 1.74(3) 1.83(3) 1.83(3) 1.8 l(3) 1.75(3) 1.85(3) 1.85(3) 1.79(3) 1.79(3) (3) 849( 1 ) 97:2(2) 84:7(1) (1) (2) 1.795(8) 1.735(8) 1.757(7) 1.920(7) 1.72 l(9) 1.880(9) 1.80 1 (7) 1.746( 7) 1.82(3) 1.80(3) 1.74(3) 1.79(3) 1.95(3) 1.72(4) I .88(4) 1.8 l(3) 1.83(3) I .8 l(3) 1.74(3) 1.77(3) 1.78(3) 1.80(3) 1.77(3) 1.79(3) 1.79(3) (3) Largest to P(l) 165.1(1) 164.3(5) 171.6(2) Largest to P(2) 166.8(1) 165.5(4) 178.3(2) from B(7) C(1) B(4) from B(2) C(6) B(6) plane through the atoms of the open face (dihedral angle 92"), but in (2) the corresponding P( 1 )-Ir-P(2) plane is inclined substantially to one side (dihedral angle 74"), allowing space for a third ligand atom (the hydride) to be attached to the Ir. Both (1) and (2) share the overall planarity of the B,C section of the face B(3), B(7), B( to), C(6) with the unique carbon atom [C(l)] somewhat above this plane.It is clear therefore that although distortions are observed in the MC,B, fragment of the cage, they are less marked than in the MC,B, cages.The attachment of the six-vertex upper plane to the five- vertex lower plane is achieved by opening out two adjacent faces so that each becomes a quadrilateral with long diagonals. The mirror symmetry is not exact, because of the asymmetrical placing of the two carbon atoms in a C-B-C arrangement around the six-vertex face, with one carbon on the pseudo- mirror plane. The presence of the second carbon causes bond shortening in the lower part of the cage, though only to a modest extent. The additional perturbation in (2) of the -0Me group attached to B(2) may shorten the bonds from B(2) slightly, but the precision of the structure determination is insufficient to be confident about this conclusion. In addition the presence of the methoxy group may be responsible for the substantial lengthening of bonds on the other side of the cage in (2) in comparison to (1).Viewed more generally, complexes (1) and (2) confirm that 13-membered metallacarboranes adopt a single specific cage geometry, even if individual compounds show slightly different distortions. The structure of (3) is more straightforward than those of (1) and (2). The nido-C,B, cage is completed by the Pt atom to give a d o s o icosahedron. The geometry of systems of this type has recently been examined in detail,' and shown to be affected by the d electron count of the metal, with the M-B bonds shortening and the M-C bonds lengthening as the number of d electrons increases.One other closely related d8 platinum(r1) complex has been examined, [(PEt3)'PtC2B9H, where the two carbon atoms in the cage are adjacent, and the dimensions of complex (3) are indistinguishable from this earlier example, indicating that the change in phosphine has no effect, even on the Pt-cage bonds. Experimental All reactions were performed under a nitrogen atmosphere using standard Schlenk-line techniques. Solvents were distilled immediately prior to use from either LiAIH, or sodium-benzo- phenone (thf). Infrared spectra were recorded using a Perkin- Elmer 580B spectrophotometer with Nujol mulls. The ' B n.m.r. spectra were obtained at 128 MHz on a Bruker WH-400J. CHEM. SOC. DALTON TRANS. 1987 1809 TaMe 2. Crystallographic data Compound Formula M System Space group Absences 4 hIA C I A 4 Pi Yl u i ~ 3 D,/g cm113 D,/g cm-3 Z p( M 0- KJcm- ' F ( o w Reflections: Total f / o ( f ) 2 3.0 2ernax I' Range (28) about z l - x 2 / " Min.speed (20)/" min-' T/K Crystal size/mm Transmission factors Max.-min. R R R' (1) (2) (3) C,,HJ,B I ,P,PdCH,CI, C,,H,,B ,IrOP2-CHCI, C28H3SB9P2Pt 773.9 1011.4 725.9 Triclinic PT None 1 1.645(4) 10.399(4) 14.975(5) 100.7 l(3) 1 O4.24( 3) 94.45(3) 1713(1) 1.42 1.38 2 8.1 748 6 056 4 786 50 & 1 . 1 2.0 290 0.23 x 0.48 x 0.32 0.55-0.39 0.007 0.039 0.043 Triclinic None PT 9.922(2) 1 1.068(2) 20.43 3( 3) 95.26( 1) 90.25( 1) 101.14(1) 1.53 1.52 2 22.3 1004 2 191.8(7) 5 100 4 130 50 & 1.1 1.2 290 0.28 x 0.07 x 0.18 0.894.76 0.007 0.074 0.077 Monoclinic P2,ln M31, h + I # 2n 0kO.k #2n 14.I8 l(2) 2 1.443( 5) 11.412(2) 90 99.83( 1) 90 3 419( 1) 1.41 1.53 4 42.1 1448 6 548 3 530 50 - + 1.0 2.0 1?3 0.21 x 0.14 x 0.42 0.79-43.6 1 Unit weights 0.068 Table 3. Final atomic co-ordinates ( x lo4) for compound (1) v 1313.1(2) 2 335( 1) 3 522(3) 3 991(4) 2 830( 13) 2 738 4 330 3 547 3 509 3 530 1 342(4) 65(4) 2 700(5) 2 791(4) I926(4) 357(5) 170(4) I414(4) 642( 5 1 2 189(5) 2 601(5) I 117(5) I 394(5) -227(1) r 2 369.5(2) 4 W 1 ) 3 557(1) - 1 814(3) 885(4) 286 749 758 0 0 5 278(4) 4 599(4) 804(5) 1667(5) I714(5) 1 202(5) 335(4) - 88(4) - 536(5) - I 282(4) - 976( 5) - 508( 15) 129( 5) 1 89( 5) - I 207(5) 2 175.3(2) 1701(1) 1911(1) 5 870(2) 6 892(3) 6 033( 10) 6 594 7 045 6 184 5 798 5 813 1515(3) 1 104(3) 2 111(4) 3 091(4) 3 698(3) 2 963(3) 1721(3) I 446(3) 2 625(4) 1 756(4) 2 141(4) 3 382(4) 3 665(3) 2 939(4) Atom C(111) C( 112) C(113) C( 114) C(115) C(116) C(121) C( 122) C( 123) C( 124) C( 125) C( 126) C(211) C(212) C(213) C(214) C(215) C(216) C(221) C(222) C(223) C(224) C( 225) C( 226) 1 2 733(4) 2 486(4) 2 776(6) 3 320(5) 3 258(4) 3 716(4) 5 817(5) 5 805(5) 4 774(6) 3 723(5) 3 547(4) 4 779(4) - I 754(4) -3 409(4) -4 106(4) - 3 620(4) - 2 453(4) - 230(4) 683(4) 740(5) - 96( 5) - 994(5) - 1 057(4) - 2 248(4) F 3 603(4) 2 318(4) 2 036(5) 3 021(6) 4 309(5) 4 592(5) 4 827(4) 4 385(5) 4 =(6) 5 833(7) 6 301(8) 5 81 l(6) 2 779(4) 2 417(4) I 823(4) 1 572(4) I890(5) 2 503(4) 4 781(4) 4 941(4) 5 968(5) 6 843(4) 6 684(4) 5 659(4) 586(3) 43(3) - 794(3) - 593( 3) 255(3) 2 555(3) 2 485(4) 3 168(4) 3 915(4) 3 979(5) 3 306(4) 444(3) 76(3) 1 640(4) 2 009(3) 2 947(3) 3 781(3) 4 535(3) 4 472(3) 3 659(4) 2 892(3) - 1 116(3) I419(3) 67 l(4) spectrometer using BF,-Et,O as an external standard, with high-field resmances being quoted as negative values. The reagents [MCl,(dppe)] (M = Pd or Pt) and [IrCI(PPh,),] were prepared by literature methods.' Microanalyses were carried out by Butterworth Laboratories Ltd.Pwpcrrurion of' [(dppe)PdC,B,,H ,,I (I).-The carborane I,2-C2B,oH,z (0.33 g, 2.3 mmol) was dissolved in thf (30 cm') containing small pieces of sodium (0.1 1 g, 4.6 mmol), and a catalytic trace of naphthalene. Stirring was continued until the sodium had reacted (cu. 2-3 h), and the clear solution was then evaporated. The residue was dissolved in degassed CH,CI, (30 cm3), and then [PdCl,(dppe)] (1.33 g, 2.3 mmol) was added slowly to the stirred solution.The resulting dark red solution1810 J. CHEM. SOC. DALTON TRANS. 1987 ~~ Table 4. Final atomic co-ordinates ( x lo4) for compound (2) Y 1 501.9(8) 2 763(5) 2 196(5) I 185(24) 538( 19) - 587(28) - 936(25) 41(24) 835( 19) - I 797(22) - 762(25) -406(25) - 1 119(24) - 2 055(28) - I 965(26) 6 259(30) 4 773( 10) 6 407( 14) 6 224( 18) 4 069( 19) 4 407(22) 4 009(25) 3 168(24) 2 81 8(20) 3 260( 18) 2 73 I(22) 2 195(23) 945(22) 223(22) 1’ 2 9 I 7.2( 7) 4 170(4) 4 197(4) 792( 16) 1 323( 13) 2 196(17) 3 082(20) 2 447(22) 1215(13) 1 875(20) 878(20) 480(20) 1 71 7(23) 372(21) 594( 2 1 ) 61 l(8) 1561(16) 2 310(15) I 535(19) 1550(23) 2 337(20) 3 164(19) 3 138(15) 5 972( 18) 6 810(20) 7 056( 17) 6 445( 18) - 96( 19) - 901 ( 1 3) 2 237.5(3) 1 502(2) 3 186(2) 2 186(11) 2 780(9) 2 741(9) 1 975( 10) 1 312(11) I443(8) 1 388( 12) 1 067( 12) 1 640(10) 2 476( 12) 2 262( 12) 1 683( 10) 3 851(12) 3 396(5) 3 956(5) 4 576(7) 989(9) 466( 11) - I70( 10) - 333( 10) 188(9) 831(9) 643(9) 313(9) 491(10) 952( 1 1 ) Atom C( 126) C(121) C( 132) C( 133) C( 134) C( 135) C( 136) C(131) C( 2 1 2) C(2 13) C(214) C(215) C(216) C(21 I ) C(222) C(223) C(224) C(225) C(226) C(221) C(232) C(233) C(234) C(235) C(236) C(231) O( 13) C(43) Y 752(20) 2 001(18) 4 304( 18) 5 514(26) 6 754(25) 6 870(20) 5 650( 19) 4 380( 17) 207(21) 530( 35) 1 856(30) 2 470(22) 1 623(20) 4 373(26) 5 730(26) 6 712(27) 6 396(25) 5 029(24) 4 021(19) 568(23) 165(28) 793(25) 1835(22) 2 228(21) I 588(18) 2 220( 13) 2 803(24) - 292(25) 1.5 560( 16) 5 303(15) 6 349( 14) 7 214(20) 6 912(21) 5 772(20) 4 892(18) 5 170(14) 5 617(17) 6 723(20) 7 829(23) 7 842(22) 6 823( 17) 5 672( 17) 5 378(22) 5 581(23) 5 018(24) 4 016(20) 4 600( 16) 3 801(20) 3 122(25) 2 181(22) I 829( 19) 2 49 1 (1 8) 3 464( 16) 88(11) 4 204(22) - 161(22) I 251(9) 1 lOl(8) 2 082(8) 2251(11) 2 140(10) 1851(10) 1 684(1 I ) 1 769(8) 3 169(9) 3 198(9) 3 269(11) 3 377( 13) 3 347(11) 3 245(8) 4 033( 10) 4 259( 10) 3 962( 1 1 ) 3 380( 10) 3 116(9) 3 450(9) 4 336( 10) 4 891(12) 5 024( 10) 4 631(10) 4 080(9) 2 287(6) 1 776( 12) 3 927(7) Table 5. Final atomic co-ordinates ( x lo4) for compound (3) Y 2 366.7(5) 3 701(3) 3 135(4) 872( 17) 621(12) I 084( 15) 1 576( 18) 1 559( 17) 278( 18) -332(16) - 163(16) 354( 20) 650( 18) 4 3lO( 14) 4 323( 13) 3 595( 14) 3 066( 15) 2 973( 15) 3 382( 16) - 452(20) 1’ 1 354.4(4) 757(2) I 976(3) 7lO( 12) I 363( 1 1 ) 1 954( 10) I 573(13) 750( 14) 543( 1 I ) 944( 13) 1 736( 12) I 854( 12) 1 106(12) I218(14) 931( 10) 1 654( 10) -85( 14) - 3 945( 15) - 1 033( I I ) - 1 373( 14) 98 1.3(6) I 154(4) - 149(4) 619(20) 12(15) 1 103(20) 2 51 l(21) 2 089( 19) I 727(22) 443(22) 744( 20) 2 261(24) 2 869(20) I873(23) - 101( 17) - 201 ( 16) I 174(17) 183(19) 147(20) I 141(23) Atom C(115) C(116) C(121) C( 122) C( 123) C( 124) C( 125) C( 126) C(211) C(212) C(213) C(214) C(215) C(216) C(221) C( 222) C( 223) C( 224) C( 225) C( 226) Y 3 877(21) 4 003( 16) 4 569( 13) 5 584( 15) 6 243( 14) 5 998( 16) 5 008( 17) 4 310(14) 3 352(12) 3 678( 14) 3 892( 18) 3 824(21) 3 501(19) 3 282( 14) 2 542( 12) 3 014(14) 2 517(16) I 527( 18) 1 103(17) 1 565(15) 1’ ‘ 1 057(21) -443(11) 948( 13) 853( 15) 1 007( 12) 1 306( 16) 1 446(17) 1281(14) 2 771(12) 3 328( 14) 3 81 l(18) 3 963(21) 3 499( 19) 2 906( 10) 2 068(9) 2 032( 14) 2 112(16) 2 243 12) 2 324( 12) 2 269( 12) 2 172(23) 2 204(18) 2 458( 17) 2 445( 19) 3 448(20) 4 397(20) 4 364( 18) 3 389( 19) 401(16) 172(23) 1 356(26) 2 038(23) 1 603(18) - 293( 19) - I 678(14) - 2 669( 17) -3 800(21) - 3 999(22) - 3 047(23) - 1 928( 18) was stirred for 0.5 h and then filtered.On exposure to air the filtrate showed a gradual colour change to a straw colour. Thin- layer chromatography (silica gel) using CH,CI, as eluant indicated the presence of the major yellow product [(dppe)- PdC,B,,H,,] (1) at R, 0.8, and a minor unidentified yellow component at R, 0.6.The complex [(dppe)PdC,B,,H, 2 ] was isolated by flash chromatography (silica gel) using CH,CI, as eluant, and was recrystallised from the same solvent (yield of yellow crystals 160 mg, 10%) (Found: C, 50.4; H, 5.65. Calc. for C2sH3,B,oP2Pd* OSCH,CI,: C, 49.5; H, 5.40%). Since the calculated analysis for the crystalline material containing 1.0 CH,CI, gives C, 47.3; H, 5.2”/,, we assume that the crystals slowly lose solvent on standing. Prvpcrrarion of’ [(PPh,),HIrC2B,,H, ,(OMe)] (3).-The compounds [NMe,][C,B, ,H , ,] (0.12 g, 0.65 mmol) and [IrCI( PPh,),] (0.66 g, 0.65 mmol) were refluxed for 24 h in a mixture of degassed light petroleum (b.p. 6&80 “C, 45 cm3) and methanol (25 cm3). The colour of the mixture gradually changed from red to reddish brown, and a pale yellow solid was precipitated.After filtration the pale yellow solid was purified by preparative t.1.c. and was eluted with CHCI,. After recovery from the plate the yellow solid was recrystallised from CHCI,J. CHEM. SOC. DALTON TRANS. 1987 181 1 (yield 80 mg, 16%) (Found: C, 47.6; H, 4.50. Calc. for C,,H,,B, ,IrOP,CHCI,: C, 47.5; H, 4.60%). Preparation of' Thallium(1) Salt from [C,B, ,H ,I2 -, Formu- luted us TI,(C,B,H,,)O.-The carborane 1,2-C2B,,H,2 (1.00 g, 6.9 mmol) was dissolved in thf (50 cm3) containing small pieces of sodium (0.32 g, 13.8 mmol) and a trace of naphthalene. After stirring for 2-3 h to complete the reaction, thallium(1) acetate (3.63 g, 13.8 mmol) was dissolved in boiling ethanol (400 cm3), and allowed to cool to 3WO"C.The solution of Na2[C,Bl ,H ,] was added to this stirred solution over 15 min, and the resulting fine orange precipitate was cooled to 0 "C and filtered. The product was washed with water (2 x 10 cm3) and ethanol (2 x 10 cm3), and finally with several portions of diethyl ether before being dried under vacuum. The product C0.87 g, 25% based on Tl(O,CMe)] was then stored under vacuum at 0 "C (Found: C, 2.90; H, 1.45; B, 13.85; T1,83.9. Calc. for C,H,,B,OTI,: C, 3.15; H, 1.60; B, 12.8; TI, 80.4%). Prepurution of' [PMePh,][C,B,H, ,].-The orange TI,- (C2B,H, ,)O (0.50 g, 0.66 mmol) and [PMePhJBr (0.24 g, 0.66 mmol) were mixed in thf (40 cm3) and stirred for 1 h. The resulting black suspension was removed by filtration, and the air-stable pale yellow filtrate was evaporated under vacuum to yield an oil residue.The residue was dissolved in CHCI, (10 cm3), and the pale yellow product was precipitated by the addition of excess of light petroleum (b.p. 60-80 "C). After filtration, and washing with light petroleum, the solid was dried under vacuum (yield 0.19 g, 70%) (Found: C, 59.6; H, 7.50. Calc. for C, , H,,B,P: C, 61.4; H, 7.35%). The ' B n.m.r. spectrum was recorded from an acetone solution. Prepuration of"(dppe)PtC,B,H, ,] (3).-A suspension of the orange solid TI,(C,B,H, ,)O (0.50 g, 0.66 mmol) was stirred and refluxed in thf (20 cm3) for 0.5 h. The resulting pale orange precipitate was removed from the deep red supernatant by filtration. The solution was evaporated to an oil which was dissolved in CHCI, (10 cm3).Cooling to -78 "C followed by the addition of excess of diethyl ether yielded a light brown solid which was collected after filtration. Thin-layer chromatography showed this material to be a mixture of products, but the compound [(dppe)PtC,B,H ,] was isolated as one of the major components by flash chromatography using CHC1,-light petroleum (b.p. 60-80 "C) (75:25 by volume) as eluant. Crystals suitable for X-ray crystallography were obtained by recrystallisation from acetone-CH,CI, (yield of crystals 30 mg, 6.32;;). CI:l'stcrl-struc.ture Anul?,sc.s.--CrystaI data and collection and refinement parameters are given in Table 2. Data were collected with a Syntex P2, four-circle diffractometer in 8-28 mode with scan speed from the specified minimum to 29" min-I, depending on the intensity of a 2-s pre-scan; backgrounds were measured at each end of the scan for 0.25 of the scan time. For (2), reflections with 28 > 35'- were only collected if they exceeded a set count on an 8-s pre-scan.For (3), the crystal was held at -100 C with the Syntex LT-1 attachment. Three standard reflections were monitored every 200 reflections, and any slight changes during data collection were corrected by rescaling. Density was measured by flotation. Unit-cell dimensions and standard deviations were obtained by least-squares fit to 15 high-angle reflections. Only observed reflections [l/o(I) 3 3.01 were used in refinement, corrected for Lorentz, polarisation and absorption effects, the last with ABSCOR.' For each compound, the heavy atom was located by Patterson techniques and the light atoms were then found on successive Fourier syntheses.Hydrogen atoms were given fixed isotropic thermal parameters, inserted at calculated positions and not refined; the hydrogens of the methyl group of (2) were omitted as was its hydride ligand. Compound (1) was found to contain a highly disordered CH,CI, molecule, which was approximated by two CI atoms with occupancy 0.7, and five carbon atoms with fixed co-ordinates and thermal parameters (0.10 A,), and occupancies refined to 0.5-0.1; it still had residual peaks up to 2 e A-3 in the neighbourhood of the solvent. Compound (2) contained a molecule of CHCI,, given occupancy 0.7. Final refinement was by cascaded least-squares methods, with anisotropic thermal parameters for all atoms other than hydrogen and some solvent atoms. The positions of the cage carbon atoms were identified principally by their shorter bonds, though the behaviour of their thermal parameters on refinement was used in confirmation.A weighting scheme of the form H' = 1/[02(F) + gF2] was used for (1) and (2); (3) was given unit weights, and all weighting schemes were checked by weight analysis. Computing for (1) and (2) was with the SHELXTL system l6 on a Data General NOVA3, following initial processing on a Burroughs B6800 computer; for (3), X-RAY 76 was used." Scattering factors in the analytical form and anomalous dispersion factors were taken from ref. 18. Final atomic co-ordinates are given in Tables 3-5. For (3), F,/F, tables could not be produced because of a loss of data files, but absorption-corrected F, data are available on request to the authors.Acknowledgements We thank the S.E.R.C. for support of this work. References 1 N. N. Greenwood, Chem. SOC. Rev., 1984,13,353; R. N. Grimes, in 'Comprehensive Organometallic Chemistry,' eds. G. W. Wilkinson, F. G. A. Stone, and E. W. Abel, Pergamon, Oxford, 1982, vol. I , p. 459; J. D. Kennedy, Prog. Inorg. Chem., 1984.32, 519. 2 H. M. Colquhoun, T. J. Greenhough, and M. G. H. Wallbridge, J. Cliem. Soc., Dulron Truns., 1985, 761 and refs. therein. 3 G. B. Dunks, R. J. Wiersema, and M. F. Hawthorne, J. Am. Cheni. Soc., 1973, 95, 3174 and refs. therein. 4 D. F. Dustin, G. B. Dunks, and M. F. Hawthorne, J. Am. Chem. Soc., 1973,s.1109. 5 C. G. Salentine and M. F. Hawthorne, Inorg. Clrmi., 1976, 15, 2872. 6 F. Y. Lu, C. E. Strouse, K. P. Callahan, C. B. Knobler, and M. F. 7 M. R. Churchill and B. G. DeBoer, Inorg. Cliem., 1974, 13, 1411. 8 J. L. Spencer, M. Green, and F. G. A. Stone, J. Chem. Soc.. Cliem. 9 H. Fowkes, N. N. Greenwood, J. D. Kennedy, and M. Thornton- 10 D. V. H0we.C. J. Jones, R. J. Wiersema.and M. F. Hawthorne, Inorg. I I W. R. Miller, L. G. Sneddon, D. C. Beer, and R. N. Grimes, J. Am. 12 D. M. P. Mingos, M. I. Forsyth, and A. J. Welch, J. Climi. So c.. 13 M. J. Hudson, R. S. Nyholm, and M. H. B. Stiddard, J. Clieni. Soc. A, 14 M. A. Bennett and D. L. Milner, J. Am. Climi. Soc.. 1969, 91, 6983. 15 N. W. Alcock. in 'Crystallographic Computing,' ed. F. Ahmed, 16 G. M.Sheldrick, SHELXTL User Manual, Nicolet Instrument Co., 17 J. M. Stewart, Technical Report TR-446, Computer Science Centre, I8 'International Tables for X-Ray Crystallography,' Kynoch Press, Hawthorne, J. Am. Cliem. Soc., 1975, 97, 428. Coniniun.. 1972, I 178. Pett, J. Clieni. Soc., Dulton Truns., 1986, 5 17. Clieni., 1971, 10, 251 6. Climi. Sot.., 1974, %, 3090. Dulton Truns.. 1978, 1363. 1968,40. M un ksgaard, Copenhagen, 1970. Madison, Wisconsin. 198 1. University of Maryland, 1976. Birmingham. 1974, vol. 4. Rewived 5th June 1986; Puper 6/ 1 1 27 J . CHEM. SOC. DALTON TRANS. 1987 1805 Metallacarboranes derived from the [C2B,oH,2]2- Anion. The Preparation, Molecular Structure, and Properties of [4- (dppe)-4- Pd-1 ,6-C2B ,,H 12], [4,4,4-H( PPh3),-2-OMe-4-lr-1 ,6-C2Bl0H,,], and [3-(dppe)-3-Pt-1.2-C2B,H,,] t Nathaniel W.Alcock, John G. Taylor, and Malcolm G. H. Wallbridge Department of Chemistry, University of Warwick, Coventry CV4 7AL The action of Na,[C,B,,H,,] on [PdCl,(dppe)] (dppe = Ph,PCH,CH,PPh,) yields the 13- vertex yellow closo species [(dppe)PdC,B,,H,,] (1 ), and the reaction of "Me,] [C,B,,H,,] with [IrCI(PPh,),] in light petroleum-methanol gives a related 13-vertex cage of yellow [( PPh,),HIrC,B,,H,,(OMe)] (2), whose formation involves attack by a solvent molecule. The structure of both products have been established by X-ray diffraction [R = 0.039 and 0.074 for 4 786 and 4 130 diffractometer-measured observed reflections, for (1 ) and (2) respectively]. Both show the characteristic 1 : 5: 6: 1 structure for 13-vertex polyhedra, distorted by carbon substitution. The reaction of TI(0,CMe) with Na,[C,B,,H,,] in ethanol leads to degradation of the C,B,, cage, and yields an orange solid formulated as TI,(C,B,H,,)O. Treatment of this solid with [ PtCl,(dppe)] gives the pale orange [ (dppe) PtC,B,H,, J (3); it has an icosahedral structure [R = 0.068 for 3 530 observed reflections], distorted mainly by the lengthening of the Pt-C bonds in comparison to the Pt-B bonds.The study of metalla-borane and -carborane derivatives con- tinues to be an active area of research, and has recently been reviewed.' We are interested in the effects resulting from the insertion of electron-rich metals (e.g. those of Group 8 and subsequent groups) into carborane frameworks, since such species often show considerable distortions in the resulting metallacarborane.2 While such distortions are now well known for the 12-vertex MC2B9 systems, we were interested to see whether similar distortions would occur in 13-vertex MC2Blo cages.Such derivatives can be easily obtained by the reaction of a metal halide derivative with the borane or carborane anion, often as the alkali-metal salt. For example, the anion [C,B,oH,z]Z- can be obtained conveniently by the action of sodium in tetrahydrofuran (thf) on the icosahedral carborane t,2-CzBl,H,2.3 Although the structure of this anion is as yet unknown, several metalla-derivatives have been character- ised,'*4-5 although detailed structural data are only available for the titanium(w)6 and cobalt(ii1) ' derivatives (Scheme).Scheme. M = Ti, Zr, Hf, V, Cr, Mo. W, Mn, Fe,Co, or Ni; L = q-C,H, or KO), We now report the preparation, properties, and structures of derivatives containing the electron-rich Group 8 metals palladium and iridium, and also the results of attempts to prepare the thallium salt of [C2Bl,H,zJ2-. This salt is expected to be a useful precursor in the preparation of other metalla-derivatives, as is found for the corresponding salt TI2CC2B9H 1 I].* t 4-[ 1 ',2'-Bis(diphenylphosphino)ethane J-c.iuso-l.6-dicarba-4-pallada- tridecdborane, 4-hydrido-2-methoxo-4,4-bis(triphenylphosphine)- closo- 1.6-dicarba-4-iridatridecaborane, and 3-[ 1 '2'-bis(diphenyl- phosphino)et hane]-c.ioso- 1,2-dicarba-3-plat inadodecaborane, respec- tively. (The numbering system employed is as suggested in J.B. Casey, W. J. Evans, and W. H. Powell, Inorg. Chem., 1981, 20, 1333.) Suppicmenfury duiu uouiluble: see Instructions for Authors, J. Chem. Soc., Dulion Truns.. 1987, Issue 1, pp. xvii-xx. 10 0 -10 -20 4Vp.p.m. Figure 1. The 128-MHz "B-{'HJ n.m.r. spectrum of [(dppe)Pd- C2B, ,H 23 in dichloromethane Results and Discussion The addition of [PdCl,(dppe)] [dppe = 1,2-bis(diphenyI- phosphino)ethane] to a dichloromethane solution of Na,- [C,B,,H,,] gives an initial red colour. On filtration in air the solution slowly changes to a straw yellow colour, and yellow crystals of [(dppe)PdC,B,,H 2] (1) were obtained after purification. Colour changes have been observed previously in transition-metal derivatives of the [C2B, ,H ,I2 - ion, and have been ascribed to the facile interconversion of structural isomer^.^ Since it appears unlikely that this colour change is associated with oxidation of the metal ion, we assume that structural changes probably occur in this case also.The difficulty of assigning a plausible structure to the1806 J. CHEM. SOC. DALTON TRANS. 1987 Figure 2. Molecular structure of [(dppe)PdC2BloHl2], (1) showing the crystallographic atomic numbering. Hydrogen atoms are omitted for clarity here and elsewhere MC,B,, framework from n.m.r. data alone has been reported previo~sly,4*~ and (1) presents similar difficulties. The best resolved 'B-{ 'H) n.m.r. spectrum at 128 MHz showed a series of five broad overlapping resonances (Figure l), and the integration based on a fragment containing ten boron atoms is unclear.While the ratio of the four resonances between + 5 and - 10 p.p.m. to that near - 18 p.p.m. is approximately 8: 2 (actually 8.8 : 2), the individual ratios of the lower-field set of four resonances are approximately 1 : 3 : 2 : 1. Since this group of resonances apparently represents eight boron atoms we assume that the overlap of the resonances causes this anomaly. The resonances broaden considerably at lower temperatures, thus at -90 ' C in CH,CI, the resonance at - 1 p.p.m. is over 800 Hz wide at half-height. Fluxionality in such 13-vertex systems has been observed previ~usly,~ and has been reasonably suggested to arise from an interchange between isomeric species which have the carbon atoms of the C2B4 face in alternative positions, it being assumed that the interchange proceeds via the squarediamond-square process.Since we were unable to make any structural assignment from the n.m.r. data a crystal-structure determination was undertaken. The resulting structure (Figure 2) confirms the presence of a 13-vertex metallacarborane cioso cluster, and shows that the two carbon atoms are separated by a boron atom in the six- membered C,B, face; this feature is similar to that observed previously in [NMe,],[Ti(C,B,,H IoMe,),J and [(q-C5H5)- CO(C,B,,H,,)].~ While there is no strong distortion of the fragment containing the d8 Pd" and the C,B, face, some asymmetry is evident (see below). A related yellow iridium derivative, [( PPh,),HIrC,B, ,H I - (OMe)] (2) was prepared by refluxing [IrCI(PPh,),] and [NMe4][C,Bl,H,,] in light petroleum (b.p.60-80 "C)- methanol. Refluxing the two reagents for 1 h in light petroleum alone produced no colour change. The I ' B n.m.r. spectrum (CH,CI, solution) showed a series of broad overlapping resonances (at least three in number) between + 17 and + 2 p.p.m., and as with (1) was unhelpful for structural assignment. A crystal-structure determination (Figure 3) revealed that an unexpected solvolysis had taken place replacing one cage B-H hydrogen by -OMe, and that (2) is the 13-vertex doso species [(PPh,),HIrC2BloHI ,(OMe)J. As with (1) the two carbon atoms are separated by a boron atom; further structural details are discussed below. The presence of the methoxy group is Figure 3. Molecular structure of [(PPh,),HIrC,B,,H, ,(OMe)] (2) showing the crystallographic atomic numbering perhaps not too surprising since other examples are known where methoxy groups are substituted into metallaboranes when the compounds are formed in alcoholic solution.' Predictably the methoxy group substitutes at the boron atom which adjoins the two carbon atoms and the metal atom. We have also attempted to prepare the thallium derivative TI, [C, B ,H , J by reacting Na, [C,B , ,H , J with thallium( I) acetate, since it is known that a similar reaction using Na2[C2B,H, '3 yields TI,[C2B,H, 3.' In the present work the interaction of an ethanol solution of thallium(1) acetate with Na,[C,B,,H, ,] in thf produced a flocculent orange precipitate.The material appeared to be heat sensitive, since attempts to coagulate the suspension by heating caused some darkening.Although the heating was carried out in the light, we have observed that the precipitate is not light sensitive, at least over a few hours. However, the precipitate could be filtered off, and after drying under vacuum yielded an orange solid. No satis- factory n.m.r. spectra could be obtained from the solid due to insolubility, but elemental analysis was not consistent with the formulation TI,[C2Bl,H12]. In view of the analytical data, and the reactions described below, it appears that a cage degradation has occurred, and the best formulation we can propose for the solid is TI,(C,B,H 2)0. When the orange solid is suspended in thf, and treated with [PMePh,]Br, the mixture slowly darkens and a black solid is precipitated.A pale yellow solid can be recovered in high yield from the supernatant after filtration, and this solid corresponds to [PMePh,][C,B,H,,] from analytical data and the "B n.m.r. spectrum. The latter shows doublets at -9.44 (relative intensity 2), - 15.2 (2), - 16.2 (l), -20.8 (2), -31.6 (I), and -36.4 (1) p.p.m.; these values are very similar to those for [C2B,H ,] - reported previously.' The i.r. spectrum of the solid shows the expected absorptions from the cation, but also gives a broad band at 2 500 cm-I whose contour is similar to that reported for the [C2B,H12]- ion." We assume that the black solid produced is T1,0, and that the overall reaction proceeds as follows. TI,(C,B,H,,)O + [PMePh,]Br - [PMePh,][C,B,H,,] + T1,O + TlBr The base degradation of C2B,,H1, to [C2B,HI2]- occurs readily when the former is treated with an NaOEt-EtOHJ.CHEM. SOC. DALTON TRANS. 1987 1807 Figure 4. Molecular structure of [(dppe)PtC2B,H, J (3) showing the crystallographic atomic numbering mixture." I n the present work the acetate ion appears to have the same effect as alkoxide, and indeed we have confirmed that even an Li(0,CMe)-EtOH mixture carries out this degrad- ation. The alternative pathways involving the formation and decomposition of an intermediate 13-vertex metallacarborane appear less likely, though such a route has been proposed to explain the formation of [(q-C5HS)Co(C,B,H, ])] from the direct action of [Co(CO),(q-C,H,)] on C2B,oH,2.1r The presence of a C2B9 fragment in the orange thallium derivative is also indicated by its interaction with [PtCI,- (dppe)]. The yellow-orange complex [(dppe)PtC,B,H (3) was isolated from the reaction mixture, and tentatively identi- fied from its I l B n.m.r.spectrum by comparison with those previously reported for similar PtC,B9 cage compounds which have the two carbon atoms occupying adjacent positions in the cage.,.' ' However, since the spectrum shows broad overlapping resonances [ + 10.1 (relative intensity l), - 10.3 ( 9 , and -21.5 (3)], an X-ray structure determination was undertaken to confirm this identification (Figure 4). Siructurcil Resu1r.y.-While the 13-vertex MC2Bl0 polyhedra in ( 1 ) and (2) are necessarily rather irregular, they share the same overall geometry, which is also common to the two pre- vious 13-vertex structures rep~rted.~.' This can best be seen from a diagram of connectivity and distances (Figure 5; cj: Figure 3 in ref.7), which shows the overall pseudo-mirror symmetry of the polyhedra.6 However, there are interesting differences between both (1) and (2), and the well defined cobalt compound. Despite the different metal electron configurations in (1) ( d 8 ) and (2) ( d 6 ) there are some similarities in the pattern of M-cage bonds (Figure 6 and Table 1). Each has the shortest link to the unique low-co-ordinate carbon atom [C(l)], and both have a significantly longer bond to an atom one away from this unique carbon. I n (1) this link is to the other carbon [Pd-C(6)], while in (2) it is to a boron atom [Ir-B(7)]; the remaining facial bonds are relatively short.This indicates both that the top C,B, layers of the cages are similar in their distortions, and that the metal atoms are attached in very much the same position relative to the centroid of the open face. In contrast, in the cobalt compound, although the Co-C(unique) bond is still the shortest, all the other M-facial bond lengths are comparable. The compounds (1) and (2) do show a significant difference because of the presence of the hydride ligand on Ir. In (I), the P( 1 )-Pd-P( 2) plane is almost perpendicular to the mean 12 1 Figure 5. Schematic representations of the carborane fragments in com- pounds (1) and (2). The atom numbers relate to boron unless otherwise indicated, bond distances in A Figure 6. Schematic representation of of the M-cage bonding in com- pounds ( I ) , (2), and [(q-C5H5)Co(C2Bl,H,2)], bond distances in A1808 J.CHEM. SOC. DALTON TRANS. 1987 Table I. Principal bond lengths (A) and angles (") for compounds (I), (2), and (3) Compound (1) Pd-P( 1 ) Pd-P(2) Pd-B( 2) Pd-B( 3) Pd-B(7) Pd-B( 10) Pd-C(6) B(2)-c( 1) Pd-C( 1 ) Compound (2) Ir-P( 1) Ir-P(2) Ir-B(2) Ir-C( 1) Ir-B(3) Ir-B(7) Ir-B( 10) Ir-C(6) B(2)-C(6) B(2)-C( 1 ) Compound (3) Pt-P( 1) Pt-P(2) Pt-C( 2) Pt-C(3) Pt-B(4) Pt-B(5) Pt-B( 6) C( 21-a 3 1 2.3 17( 1) 2.252( 1) 2.387(5) 2.187( 5 ) 2.455( 5 ) 2.252(6) 2.300( 4) 2.609(4) 1.546(7) 2.340(5) 2.3 12(4) 2.305( 18) 2.230( 16) 2.350( 25) 2.520( 15) 2.3 36( 22) 2.360( 15) 1.69(3) 1.50(3) 2.266( 3) 2.259(3) 2.502( 3) 2.505(3) 2.251 (3) 2.279(3) 2.255(3) 1.53(3) B-M-P angles (1) Smallest to P( 1) 97.4( 1 ) from B(2) Smallest to F(2) 89.8(1) from B(7) 1.674(6) 1.912(7) 2.173(7) 1.5 12(8) 1.746( 8) 1.865(7) 1.91 l(7) 1.767(7) 1.862(6) 1.97(3) 2.33(3) 1.43(2) 1.44(3) 1.62(3) 1.80(3) 1.99( 3) 1.90(3) I .72( 3) 1.74(3) 1.71(3) 1.63(3) I .79(3) 1.67(3) 1.76(3) 1.83(3) 1.81(3) 1.769(7) 1.760(7) 1.669(7) 1.800( 8) 1.816(7) 1.677(7) 1.666( 7) 1.737(8) 1.754(6) 1.62(3) 1.84(3) I .79(3) 1.84( 3) 1.74( 3) 1.82(3) 1.79(3) 1.72(3) 1.79(3) 1.74(3) 1.83(3) 1.83(3) 1.8 l(3) 1.75(3) 1.85(3) 1.85(3) 1.79(3) 1.79(3) (3) 849( 1 ) 97:2(2) 84:7(1) (1) (2) 1.795(8) 1.735(8) 1.757(7) 1.920(7) 1.72 l(9) 1.880(9) 1.80 1 (7) 1.746( 7) 1.82(3) 1.80(3) 1.74(3) 1.79(3) 1.95(3) 1.72(4) I .88(4) 1.8 l(3) 1.83(3) I .8 l(3) 1.74(3) 1.77(3) 1.78(3) 1.80(3) 1.77(3) 1.79(3) 1.79(3) (3) Largest to P(l) 165.1(1) 164.3(5) 171.6(2) Largest to P(2) 166.8(1) 165.5(4) 178.3(2) from B(7) C(1) B(4) from B(2) C(6) B(6) plane through the atoms of the open face (dihedral angle 92"), but in (2) the corresponding P( 1 )-Ir-P(2) plane is inclined substantially to one side (dihedral angle 74"), allowing space for a third ligand atom (the hydride) to be attached to the Ir.Both (1) and (2) share the overall planarity of the B,C section of the face B(3), B(7), B( to), C(6) with the unique carbon atom [C(l)] somewhat above this plane. It is clear therefore that although distortions are observed in the MC,B, fragment of the cage, they are less marked than in the MC,B, cages. The attachment of the six-vertex upper plane to the five- vertex lower plane is achieved by opening out two adjacent faces so that each becomes a quadrilateral with long diagonals.The mirror symmetry is not exact, because of the asymmetrical placing of the two carbon atoms in a C-B-C arrangement around the six-vertex face, with one carbon on the pseudo- mirror plane. The presence of the second carbon causes bond shortening in the lower part of the cage, though only to a modest extent. The additional perturbation in (2) of the -0Me group attached to B(2) may shorten the bonds from B(2) slightly, but the precision of the structure determination is insufficient to be confident about this conclusion. In addition the presence of the methoxy group may be responsible for the substantial lengthening of bonds on the other side of the cage in (2) in comparison to (1).Viewed more generally, complexes (1) and (2) confirm that 13-membered metallacarboranes adopt a single specific cage geometry, even if individual compounds show slightly different distortions. The structure of (3) is more straightforward than those of (1) and (2). The nido-C,B, cage is completed by the Pt atom to give a d o s o icosahedron. The geometry of systems of this type has recently been examined in detail,' and shown to be affected by the d electron count of the metal, with the M-B bonds shortening and the M-C bonds lengthening as the number of d electrons increases. One other closely related d8 platinum(r1) complex has been examined, [(PEt3)'PtC2B9H, where the two carbon atoms in the cage are adjacent, and the dimensions of complex (3) are indistinguishable from this earlier example, indicating that the change in phosphine has no effect, even on the Pt-cage bonds.Experimental All reactions were performed under a nitrogen atmosphere using standard Schlenk-line techniques. Solvents were distilled immediately prior to use from either LiAIH, or sodium-benzo- phenone (thf). Infrared spectra were recorded using a Perkin- Elmer 580B spectrophotometer with Nujol mulls. The ' B n.m.r. spectra were obtained at 128 MHz on a Bruker WH-400J. CHEM. SOC. DALTON TRANS. 1987 1809 TaMe 2. Crystallographic data Compound Formula M System Space group Absences 4 hIA C I A 4 Pi Yl u i ~ 3 D,/g cm113 D,/g cm-3 Z p( M 0- KJcm- ' F ( o w Reflections: Total f / o ( f ) 2 3.0 2ernax I' Range (28) about z l - x 2 / " Min.speed (20)/" min-' T/K Crystal size/mm Transmission factors Max.-min. R R R' (1) (2) (3) C,,HJ,B I ,P,PdCH,CI, C,,H,,B ,IrOP2-CHCI, C28H3SB9P2Pt 773.9 1011.4 725.9 Triclinic PT None 1 1.645(4) 10.399(4) 14.975(5) 100.7 l(3) 1 O4.24( 3) 94.45(3) 1713(1) 1.42 1.38 2 8.1 748 6 056 4 786 50 & 1 . 1 2.0 290 0.23 x 0.48 x 0.32 0.55-0.39 0.007 0.039 0.043 Triclinic None PT 9.922(2) 1 1.068(2) 20.43 3( 3) 95.26( 1) 90.25( 1) 101.14(1) 1.53 1.52 2 22.3 1004 2 191.8(7) 5 100 4 130 50 & 1.1 1.2 290 0.28 x 0.07 x 0.18 0.894.76 0.007 0.074 0.077 Monoclinic P2,ln M31, h + I # 2n 0kO.k #2n 14. I8 l(2) 2 1.443( 5) 11.412(2) 90 99.83( 1) 90 3 419( 1) 1.41 1.53 4 42.1 1448 6 548 3 530 50 - + 1.0 2.0 1?3 0.21 x 0.14 x 0.42 0.79-43.6 1 Unit weights 0.068 Table 3. Final atomic co-ordinates ( x lo4) for compound (1) v 1313.1(2) 2 335( 1) 3 522(3) 3 991(4) 2 830( 13) 2 738 4 330 3 547 3 509 3 530 1 342(4) 65(4) 2 700(5) 2 791(4) I926(4) 357(5) 170(4) I414(4) 642( 5 1 2 189(5) 2 601(5) I 117(5) I 394(5) -227(1) r 2 369.5(2) 4 W 1 ) 3 557(1) - 1 814(3) 885(4) 286 749 758 0 0 5 278(4) 4 599(4) 804(5) 1667(5) I714(5) 1 202(5) 335(4) - 88(4) - 536(5) - I 282(4) - 976( 5) - 508( 15) 129( 5) 1 89( 5) - I 207(5) 2 175.3(2) 1701(1) 1911(1) 5 870(2) 6 892(3) 6 033( 10) 6 594 7 045 6 184 5 798 5 813 1515(3) 1 104(3) 2 111(4) 3 091(4) 3 698(3) 2 963(3) 1721(3) I 446(3) 2 625(4) 1 756(4) 2 141(4) 3 382(4) 3 665(3) 2 939(4) Atom C(111) C( 112) C(113) C( 114) C(115) C(116) C(121) C( 122) C( 123) C( 124) C( 125) C( 126) C(211) C(212) C(213) C(214) C(215) C(216) C(221) C(222) C(223) C(224) C( 225) C( 226) 1 2 733(4) 2 486(4) 2 776(6) 3 320(5) 3 258(4) 3 716(4) 5 817(5) 5 805(5) 4 774(6) 3 723(5) 3 547(4) 4 779(4) - I 754(4) -3 409(4) -4 106(4) - 3 620(4) - 2 453(4) - 230(4) 683(4) 740(5) - 96( 5) - 994(5) - 1 057(4) - 2 248(4) F 3 603(4) 2 318(4) 2 036(5) 3 021(6) 4 309(5) 4 592(5) 4 827(4) 4 385(5) 4 =(6) 5 833(7) 6 301(8) 5 81 l(6) 2 779(4) 2 417(4) I 823(4) 1 572(4) I890(5) 2 503(4) 4 781(4) 4 941(4) 5 968(5) 6 843(4) 6 684(4) 5 659(4) 586(3) 43(3) - 794(3) - 593( 3) 255(3) 2 555(3) 2 485(4) 3 168(4) 3 915(4) 3 979(5) 3 306(4) 444(3) 76(3) 1 640(4) 2 009(3) 2 947(3) 3 781(3) 4 535(3) 4 472(3) 3 659(4) 2 892(3) - 1 116(3) I419(3) 67 l(4) spectrometer using BF,-Et,O as an external standard, with high-field resmances being quoted as negative values.The reagents [MCl,(dppe)] (M = Pd or Pt) and [IrCI(PPh,),] were prepared by literature methods.' Microanalyses were carried out by Butterworth Laboratories Ltd. Pwpcrrurion of' [(dppe)PdC,B,,H ,,I (I).-The carborane I,2-C2B,oH,z (0.33 g, 2.3 mmol) was dissolved in thf (30 cm') containing small pieces of sodium (0.1 1 g, 4.6 mmol), and a catalytic trace of naphthalene. Stirring was continued until the sodium had reacted (cu. 2-3 h), and the clear solution was then evaporated. The residue was dissolved in degassed CH,CI, (30 cm3), and then [PdCl,(dppe)] (1.33 g, 2.3 mmol) was added slowly to the stirred solution. The resulting dark red solution1810 J. CHEM. SOC. DALTON TRANS. 1987 ~~ Table 4. Final atomic co-ordinates ( x lo4) for compound (2) Y 1 501.9(8) 2 763(5) 2 196(5) I 185(24) 538( 19) - 587(28) - 936(25) 41(24) 835( 19) - I 797(22) - 762(25) -406(25) - 1 119(24) - 2 055(28) - I 965(26) 6 259(30) 4 773( 10) 6 407( 14) 6 224( 18) 4 069( 19) 4 407(22) 4 009(25) 3 168(24) 2 81 8(20) 3 260( 18) 2 73 I(22) 2 195(23) 945(22) 223(22) 1’ 2 9 I 7.2( 7) 4 170(4) 4 197(4) 792( 16) 1 323( 13) 2 196(17) 3 082(20) 2 447(22) 1215(13) 1 875(20) 878(20) 480(20) 1 71 7(23) 372(21) 594( 2 1 ) 61 l(8) 1561(16) 2 310(15) I 535(19) 1550(23) 2 337(20) 3 164(19) 3 138(15) 5 972( 18) 6 810(20) 7 056( 17) 6 445( 18) - 96( 19) - 901 ( 1 3) 2 237.5(3) 1 502(2) 3 186(2) 2 186(11) 2 780(9) 2 741(9) 1 975( 10) 1 312(11) I443(8) 1 388( 12) 1 067( 12) 1 640(10) 2 476( 12) 2 262( 12) 1 683( 10) 3 851(12) 3 396(5) 3 956(5) 4 576(7) 989(9) 466( 11) - I70( 10) - 333( 10) 188(9) 831(9) 643(9) 313(9) 491(10) 952( 1 1 ) Atom C( 126) C(121) C( 132) C( 133) C( 134) C( 135) C( 136) C(131) C( 2 1 2) C(2 13) C(214) C(215) C(216) C(21 I ) C(222) C(223) C(224) C(225) C(226) C(221) C(232) C(233) C(234) C(235) C(236) C(231) O( 13) C(43) Y 752(20) 2 001(18) 4 304( 18) 5 514(26) 6 754(25) 6 870(20) 5 650( 19) 4 380( 17) 207(21) 530( 35) 1 856(30) 2 470(22) 1 623(20) 4 373(26) 5 730(26) 6 712(27) 6 396(25) 5 029(24) 4 021(19) 568(23) 165(28) 793(25) 1835(22) 2 228(21) I 588(18) 2 220( 13) 2 803(24) - 292(25) 1.5 560( 16) 5 303(15) 6 349( 14) 7 214(20) 6 912(21) 5 772(20) 4 892(18) 5 170(14) 5 617(17) 6 723(20) 7 829(23) 7 842(22) 6 823( 17) 5 672( 17) 5 378(22) 5 581(23) 5 018(24) 4 016(20) 4 600( 16) 3 801(20) 3 122(25) 2 181(22) I 829( 19) 2 49 1 (1 8) 3 464( 16) 88(11) 4 204(22) - 161(22) I 251(9) 1 lOl(8) 2 082(8) 2251(11) 2 140(10) 1851(10) 1 684(1 I ) 1 769(8) 3 169(9) 3 198(9) 3 269(11) 3 377( 13) 3 347(11) 3 245(8) 4 033( 10) 4 259( 10) 3 962( 1 1 ) 3 380( 10) 3 116(9) 3 450(9) 4 336( 10) 4 891(12) 5 024( 10) 4 631(10) 4 080(9) 2 287(6) 1 776( 12) 3 927(7) Table 5.Final atomic co-ordinates ( x lo4) for compound (3) Y 2 366.7(5) 3 701(3) 3 135(4) 872( 17) 621(12) I 084( 15) 1 576( 18) 1 559( 17) 278( 18) -332(16) - 163(16) 354( 20) 650( 18) 4 3lO( 14) 4 323( 13) 3 595( 14) 3 066( 15) 2 973( 15) 3 382( 16) - 452(20) 1’ 1 354.4(4) 757(2) I 976(3) 7lO( 12) I 363( 1 1 ) 1 954( 10) I 573(13) 750( 14) 543( 1 I ) 944( 13) 1 736( 12) I 854( 12) 1 106(12) I218(14) 931( 10) 1 654( 10) -85( 14) - 3 945( 15) - 1 033( I I ) - 1 373( 14) 98 1.3(6) I 154(4) - 149(4) 619(20) 12(15) 1 103(20) 2 51 l(21) 2 089( 19) I 727(22) 443(22) 744( 20) 2 261(24) 2 869(20) I873(23) - 101( 17) - 201 ( 16) I 174(17) 183(19) 147(20) I 141(23) Atom C(115) C(116) C(121) C( 122) C( 123) C( 124) C( 125) C( 126) C(211) C(212) C(213) C(214) C(215) C(216) C(221) C( 222) C( 223) C( 224) C( 225) C( 226) Y 3 877(21) 4 003( 16) 4 569( 13) 5 584( 15) 6 243( 14) 5 998( 16) 5 008( 17) 4 310(14) 3 352(12) 3 678( 14) 3 892( 18) 3 824(21) 3 501(19) 3 282( 14) 2 542( 12) 3 014(14) 2 517(16) I 527( 18) 1 103(17) 1 565(15) 1’ ‘ 1 057(21) -443(11) 948( 13) 853( 15) 1 007( 12) 1 306( 16) 1 446(17) 1281(14) 2 771(12) 3 328( 14) 3 81 l(18) 3 963(21) 3 499( 19) 2 906( 10) 2 068(9) 2 032( 14) 2 112(16) 2 243 12) 2 324( 12) 2 269( 12) 2 172(23) 2 204(18) 2 458( 17) 2 445( 19) 3 448(20) 4 397(20) 4 364( 18) 3 389( 19) 401(16) 172(23) 1 356(26) 2 038(23) 1 603(18) - 293( 19) - I 678(14) - 2 669( 17) -3 800(21) - 3 999(22) - 3 047(23) - 1 928( 18) was stirred for 0.5 h and then filtered.On exposure to air the filtrate showed a gradual colour change to a straw colour. Thin- layer chromatography (silica gel) using CH,CI, as eluant indicated the presence of the major yellow product [(dppe)- PdC,B,,H,,] (1) at R, 0.8, and a minor unidentified yellow component at R, 0.6. The complex [(dppe)PdC,B,,H, 2 ] was isolated by flash chromatography (silica gel) using CH,CI, as eluant, and was recrystallised from the same solvent (yield of yellow crystals 160 mg, 10%) (Found: C, 50.4; H, 5.65.Calc. for C2sH3,B,oP2Pd* OSCH,CI,: C, 49.5; H, 5.40%). Since the calculated analysis for the crystalline material containing 1.0 CH,CI, gives C, 47.3; H, 5.2”/,, we assume that the crystals slowly lose solvent on standing. Prvpcrrarion of’ [(PPh,),HIrC2B,,H, ,(OMe)] (3).-The compounds [NMe,][C,B, ,H , ,] (0.12 g, 0.65 mmol) and [IrCI( PPh,),] (0.66 g, 0.65 mmol) were refluxed for 24 h in a mixture of degassed light petroleum (b.p. 6&80 “C, 45 cm3) and methanol (25 cm3). The colour of the mixture gradually changed from red to reddish brown, and a pale yellow solid was precipitated. After filtration the pale yellow solid was purified by preparative t.1.c. and was eluted with CHCI,. After recovery from the plate the yellow solid was recrystallised from CHCI,J.CHEM. SOC. DALTON TRANS. 1987 181 1 (yield 80 mg, 16%) (Found: C, 47.6; H, 4.50. Calc. for C,,H,,B, ,IrOP,CHCI,: C, 47.5; H, 4.60%). Preparation of' Thallium(1) Salt from [C,B, ,H ,I2 -, Formu- luted us TI,(C,B,H,,)O.-The carborane 1,2-C2B,,H,2 (1.00 g, 6.9 mmol) was dissolved in thf (50 cm3) containing small pieces of sodium (0.32 g, 13.8 mmol) and a trace of naphthalene. After stirring for 2-3 h to complete the reaction, thallium(1) acetate (3.63 g, 13.8 mmol) was dissolved in boiling ethanol (400 cm3), and allowed to cool to 3WO"C. The solution of Na2[C,Bl ,H ,] was added to this stirred solution over 15 min, and the resulting fine orange precipitate was cooled to 0 "C and filtered.The product was washed with water (2 x 10 cm3) and ethanol (2 x 10 cm3), and finally with several portions of diethyl ether before being dried under vacuum. The product C0.87 g, 25% based on Tl(O,CMe)] was then stored under vacuum at 0 "C (Found: C, 2.90; H, 1.45; B, 13.85; T1,83.9. Calc. for C,H,,B,OTI,: C, 3.15; H, 1.60; B, 12.8; TI, 80.4%). Prepurution of' [PMePh,][C,B,H, ,].-The orange TI,- (C2B,H, ,)O (0.50 g, 0.66 mmol) and [PMePhJBr (0.24 g, 0.66 mmol) were mixed in thf (40 cm3) and stirred for 1 h. The resulting black suspension was removed by filtration, and the air-stable pale yellow filtrate was evaporated under vacuum to yield an oil residue. The residue was dissolved in CHCI, (10 cm3), and the pale yellow product was precipitated by the addition of excess of light petroleum (b.p.60-80 "C). After filtration, and washing with light petroleum, the solid was dried under vacuum (yield 0.19 g, 70%) (Found: C, 59.6; H, 7.50. Calc. for C, , H,,B,P: C, 61.4; H, 7.35%). The ' B n.m.r. spectrum was recorded from an acetone solution. Prepuration of"(dppe)PtC,B,H, ,] (3).-A suspension of the orange solid TI,(C,B,H, ,)O (0.50 g, 0.66 mmol) was stirred and refluxed in thf (20 cm3) for 0.5 h. The resulting pale orange precipitate was removed from the deep red supernatant by filtration. The solution was evaporated to an oil which was dissolved in CHCI, (10 cm3). Cooling to -78 "C followed by the addition of excess of diethyl ether yielded a light brown solid which was collected after filtration. Thin-layer chromatography showed this material to be a mixture of products, but the compound [(dppe)PtC,B,H ,] was isolated as one of the major components by flash chromatography using CHC1,-light petroleum (b.p.60-80 "C) (75:25 by volume) as eluant. Crystals suitable for X-ray crystallography were obtained by recrystallisation from acetone-CH,CI, (yield of crystals 30 mg, 6.32;;). CI:l'stcrl-struc.ture Anul?,sc.s.--CrystaI data and collection and refinement parameters are given in Table 2. Data were collected with a Syntex P2, four-circle diffractometer in 8-28 mode with scan speed from the specified minimum to 29" min-I, depending on the intensity of a 2-s pre-scan; backgrounds were measured at each end of the scan for 0.25 of the scan time. For (2), reflections with 28 > 35'- were only collected if they exceeded a set count on an 8-s pre-scan. For (3), the crystal was held at -100 C with the Syntex LT-1 attachment. Three standard reflections were monitored every 200 reflections, and any slight changes during data collection were corrected by rescaling.Density was measured by flotation. Unit-cell dimensions and standard deviations were obtained by least-squares fit to 15 high-angle reflections. Only observed reflections [l/o(I) 3 3.01 were used in refinement, corrected for Lorentz, polarisation and absorption effects, the last with ABSCOR.' For each compound, the heavy atom was located by Patterson techniques and the light atoms were then found on successive Fourier syntheses. Hydrogen atoms were given fixed isotropic thermal parameters, inserted at calculated positions and not refined; the hydrogens of the methyl group of (2) were omitted as was its hydride ligand.Compound (1) was found to contain a highly disordered CH,CI, molecule, which was approximated by two CI atoms with occupancy 0.7, and five carbon atoms with fixed co-ordinates and thermal parameters (0.10 A,), and occupancies refined to 0.5-0.1; it still had residual peaks up to 2 e A-3 in the neighbourhood of the solvent. Compound (2) contained a molecule of CHCI,, given occupancy 0.7. Final refinement was by cascaded least-squares methods, with anisotropic thermal parameters for all atoms other than hydrogen and some solvent atoms. The positions of the cage carbon atoms were identified principally by their shorter bonds, though the behaviour of their thermal parameters on refinement was used in confirmation. A weighting scheme of the form H' = 1/[02(F) + gF2] was used for (1) and (2); (3) was given unit weights, and all weighting schemes were checked by weight analysis. Computing for (1) and (2) was with the SHELXTL system l6 on a Data General NOVA3, following initial processing on a Burroughs B6800 computer; for (3), X-RAY 76 was used." Scattering factors in the analytical form and anomalous dispersion factors were taken from ref. 18. Final atomic co-ordinates are given in Tables 3-5. For (3), F,/F, tables could not be produced because of a loss of data files, but absorption-corrected F, data are available on request to the authors. Acknowledgements We thank the S.E.R.C. for support of this work. References 1 N. N. Greenwood, Chem. SOC. Rev., 1984,13,353; R. N. Grimes, in 'Comprehensive Organometallic Chemistry,' eds. G. W. Wilkinson, F. G. A. Stone, and E. W. Abel, Pergamon, Oxford, 1982, vol. I , p. 459; J. D. Kennedy, Prog. Inorg. Chem., 1984.32, 519. 2 H. M. Colquhoun, T. J. Greenhough, and M. G. H. Wallbridge, J. Cliem. Soc., Dulron Truns., 1985, 761 and refs. therein. 3 G. B. Dunks, R. J. Wiersema, and M. F. Hawthorne, J. Am. Cheni. Soc., 1973, 95, 3174 and refs. therein. 4 D. F. Dustin, G. B. Dunks, and M. F. Hawthorne, J. Am. Chem. Soc., 1973,s. 1109. 5 C. G. Salentine and M. F. Hawthorne, Inorg. Clrmi., 1976, 15, 2872. 6 F. Y. Lu, C. E. Strouse, K. P. Callahan, C. B. Knobler, and M. F. 7 M. R. Churchill and B. G. DeBoer, Inorg. Cliem., 1974, 13, 1411. 8 J. L. Spencer, M. Green, and F. G. A. Stone, J. Chem. Soc.. Cliem. 9 H. Fowkes, N. N. Greenwood, J. D. Kennedy, and M. Thornton- 10 D. V. H0we.C. J. Jones, R. J. Wiersema.and M. F. Hawthorne, Inorg. I I W. R. Miller, L. G. Sneddon, D. C. Beer, and R. N. Grimes, J. Am. 12 D. M. P. Mingos, M. I. Forsyth, and A. J. Welch, J. Climi. So c.. 13 M. J. Hudson, R. S. Nyholm, and M. H. B. Stiddard, J. Clieni. Soc. A, 14 M. A. Bennett and D. L. Milner, J. Am. Climi. Soc.. 1969, 91, 6983. 15 N. W. Alcock. in 'Crystallographic Computing,' ed. F. Ahmed, 16 G. M. Sheldrick, SHELXTL User Manual, Nicolet Instrument Co., 17 J. M. Stewart, Technical Report TR-446, Computer Science Centre, I8 'International Tables for X-Ray Crystallography,' Kynoch Press, Hawthorne, J. Am. Cliem. Soc., 1975, 97, 428. Coniniun.. 1972, I 178. Pett, J. Clieni. Soc., Dulton Truns., 1986, 5 17. Clieni., 1971, 10, 251 6. Climi. Sot.., 1974, %, 3090. Dulton Truns.. 1978, 1363. 1968,40. M un ksgaard, Copenhagen, 1970. Madison, Wisconsin. 198 1. University of Maryland, 1976. Birmingham. 1974, vol. 4. Rewived 5th June 1986; Puper 6/ 1 1 27

ISSN:1477-9226    

DOI:10.1039/DT9870001805

出版商:RSC    

年代:1987

数据来源: RSC