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J. CHEM. soc. DALTON TRANS. 1994 345 1Promotion of Tetrahedral Copperti) Dimers by Chelation ofI ,I '-Bis(dipheny1phosphino)ferrocene (dppf ). -CrystalStructures of [{Cu(p-X)(dppf-P,P)),](X =O,CH, I or NO,) tSoh Ping Nee/ Zhong-Yuan Zhou/ Thomas C. W. Mak*Sb and T. S. Andy Hor*saa Department of Chemistry, Faculty of Science, National University of Singapore, 051 I , SingaporeDepartment of Chemistry, The Chinese University of Hong Kong, Shatin, N. T., Hong KongTreatment of Cu(NO,), with 1.1 '-bis(dipheny1phosphino)ferrocene (dppf) gave [{Cu(p-NO,-0) (dppf-PP)},] which readily exchanged with Na0,CH or KI to give [(Cu(p-0,CH-0,O') (dppf-P,P')},] or[{Cu(p-I) (dppf-PF)},]. X-Ray structural analysis of the complexes revealed three tetrahedral copper(\)dimers with nitrate, iodide or formate preferentially in bridging and dppf consistently in chelating modes.The P-Cu-P chelate angle in the nitrate [117.8(1 )"I is the largest of known dppf chelates in all geometries.These structures are different from their triphenylphosphine analogues which are all monomers.Exchangesof the nitrate complex with other carboxylates gave [{Cu(p-O,CR)(dppf-PP')},] (R = Me, CF,. Et,Pr" or Ph). It also reacted with a stoichiometric amount of dppf to give [Cu,(NO,-O),(p-dppf)(dppf-P,P'),]. The geometrical influence of PPh,, Ph,PCH,PPh, and dppf, and their preferred bonding modesto Cu' in relation to the complex nuclearity, are discussed.Recent reports on 1,l '-bis(dipheny1phosphino)ferrocene (dppf)have emphasized the variety of its co-ordination modes.' Thisvariety is ascribed to its skeletal flexibility which, whencompounded by variations in metal geometries, complexnuclearities and bonding modes of co-ligands, has led to theisolation of many intriguing structures., These structures areoften unpredictable as a result of a number of bondingcontributions and an array of possible permutations in metalgeometries and co-ordination modes.The complexity is bestillustrated by the Group 11 d" metals which generally do notshow a clear preference for any particular geometry. Di-, oligo-,and poly-merization are hence common. A recent report alsohighlights the steric influence of phosphines on the structures ofsome carboxylato complexes of Cu' and CU".~ Some rep-resentative examples of dppf complexes are summarized inTable 1.There are emerging examples of dppf co-ordinated toAg' and Au'. On the other hand, the only structurallycharacterized examples for Cu' are the binary complexes[C~,(p-dppf)(dppf-P,P')~]X, (X =. BF, or C1O4).* Theseundergo partial dissociation in solution to give a mononuclearcomplex, with dppf in its unidentate mode. In order tounderstand the 'natural' co-ordination mode of dppf with Cu',we have examined the structures of three complexes [{CuX-(dppf)),] (X = I, HCO, or NO3) in which both X anddppf can opt for any of the three common bonding modes,terminal (unidentate), chelating or bridging. The number ofpermutations which decide the resultant structures, especiallywhen dimerization and oligomerization are also considered, arehence numerous.Iodide, formate and nitrate are ligands ofchoice because of their minimum steric demand and flexiblemodes of co-ordination. A related example for Ag' is found in[Ag2(02CH-O)2(dppf-P,P')2(p-dppf)]5 A in which formate isunidentate and two co-ordination modes are adopted by dppf.The iodo complex was briefly reported but the structure isunclear.presence of phosphine in methanol has been reported in asimilar reaction with PPh,.', However, unlike the PPh,complex which is monomeric, 1 is presumed to be dimeric basedon its similar IR absorptions bands with those of its silver(1)analogue. X-Ray diffraction analysis confirmed that thecomplex consists of two Cu(dppf-P,P') moieties linked by twosingle-oxygen-atom bridging nitrates (Fig.1). Selected bonddata are listed in Table 2, crystallographic details in Table 3,and atomic coordinates in Table 4. The structural frameworkcontrasts that of its silver(x) analogue in which a Ag,(p-dppf),metallocycle is supported by two bridging dppf. The one-atombridging mode of nitrate gives a Cu,O, core in 1. This is rarecompared to the symmetrical synlsyn co-ordination throughseparate oxygens. l 5 Similar bridges have been reported in[(Ag(p-NO,)(PR,)),] (R = PhI6 or OMe 17). The Cu-0 linksin 1 are covalent and approximately equidistant [2.154(6) us.2.17 l(6) A]. It readily exchanges with Na0,CH to give [{Cu(p-0,CH-O,O')(dppf-P,P')) ,] 2. Molecular-weight analysis inCH,Cl, suggests it to be dimeric.The band separation betweenvsym and vaSym (255 cm-') is considerably larger than thosefound for the typical formato-bridged complexes. l 8 An X-raycrystallographic analysis was hence carried out to ascertain itsstructure. It confirms a centrosymmetric copper(1) dimer withformate in a bidentate end-to-end bridging mode and thebulkier dppf taking up a chelating position (Fig. 2). Severalstructural features are found in 2. (i) As a result of this doublybridged framework, the complex can be configured as anResults and DiscussionTreatment of Cu(NO,), with dppf gives a complex analysing as[{Cu(NO,)(dppf)),] l.', The facile reduction of Cu" in thet Supplementary data available: see Instructions for Authors, J. Chem.SOC., Dalton Trans., 1994, Issue 1, pp.xxiii-xxviii3452 J. CHEM. SOC. DALTON TRANS. 1994Table 1 Some representative dppf complexes of Cu', Ag' and Au'Metal Complex Metal geometryAu' rAu,Cl2(dPPf)l Linear r (AuCWPPf)l"l Trigonal planar[Au,(dppf)JX, (X = NO, or ClO,) Trigonal planarCAg,(O*CPh),(dPPf)l Trigonal planarCAg,(O,CH)AdPPf),l Tetrahedral c {Ag,(O,CMe),(dPPf)},I TetrahedralCAg,(dPPf),lpF, Trigonal planarcu' [Cu,(dppf),]X, (X = CIO, or BF,) Trigonal planarCCu,(dPPf)2(biPYm>lCBF412 * Distorted tetrahedralAg' c MNO,)(dPPf)I 21 Pseudo-planar* bipym = 2,2'-Bipyrimidine.NuclearityDinuclearPolymericDinuclearDinuclearDinuclearDinuclearTetranuclearDinuclearDinuclearDinuclearBonding mode of dppfSingly bridgingSingly bridgingSingly bridging and chelatingDoubly bridgingCo-bridging with two benzoatesSingly bridging and chelatingCo-bridging with two acetatesSingly bridging and chelatingSingly bridging and chelatingChelatingRef.65, 78 , 955551041 1Fig.1 Molecular structure of [(Cu(p-NO,-O)(dppf-P,P')),I 1 [ferrocenyl and phenyl groups on Cu( 1 a) removed for clarity]eight-membered ring sandwiched between two ferrocenyl rings.(ii) The preference of formate for bridging and dppf forchelating at tetrahedral copper(1) avoids the formation of aunidentate mode for either ligand which bears a basic danglingsite (B and C), or a strained four-membered ring for a chelatingformate (C and D). Bidentate formato-bridged complexes arecommon in the literature,'*,'' but dinuclear or chain complexescontaining solely formate as bridges are rare.A notableexample of the latter is found in [Ca,Cu(O,CH),] (x = 1, y =4; x = 2, y =6),20 a precursor for superconducting oxidematerials. (iii) The formate ligands are bridging in an anti-synconformation in order to accommodate the tetrahedral demandof the metals. The resultant configuration illustrates how aformate bridge with its small bite (0 0 . . 0, 2.216 A) canmaximize the separation between two non-bonding metalcentres (Cu Cu 4.561 A).Similar replacement with other carboxylates can be carriedout to give [{Cu(p-O,CR)(dppf-P,P')},] (R = Me 3, CF, 4,Et 5, Pr" 6 or Ph 7). These metathesis reactions are summarizedin Scheme 1 . Infrared (KBr) analysis and a representativemolecular-weight analysis (CH,Cl,) on 7 suggests an iso-structural dimeric structure for all complexes except 6 whichdissociates substantially in solution based on its molecular-weight data.Molecular-weight measurement of 7 suggestssignificant aggregation in benzene. With dppf in a chelatingmode, the aggregates are held together by carboxylate bridges.The detailed solid-state structures of these complexes areuncertain without X-ray analysis. Some possible structures forthe carboxylate phosphine complexes of Cu' have beendiscussed.2 The bis(dipheny1phosphino)methane (dppm) ana-logue of 7, for example, gives two linkage isomers, both withbridging dppm, but one with unidentate benzoate (E) and theother with benzoate bridging and unidentate (F).22Nitrate displacement in complex 1 by iodide also gives adinuclear complex [{ Cu(p-I)(dppf-P,P')} ,] 8 with bridgingiodo and chelating dppf.This complex was first reported byDavison and co-workers,'2 being prepared by direct addition ofCuI to dppf. The structure was not determined but themolecular formula appears to imply a mononuclear complex G.As the present X-ray analysis shows, 8 is in fact dimeric in thesolid state. It is centrosymmetric with iodide in bridging anddppf in chelating modes (Fig. 3). The planarity of the centralfour-membered ring, which is crystallographically imposed,contrasts the folded structures found in other Cu,(p-I),dimers. 2 3The compound dppf is frequently compared with PPh, anddppm as a ligand.In many catalytic reactions the catalyticprecursor bearing two monodentate PPh, or a bidentatJ . CHEM. SOC. DALTON TRANS. 1994 3453Table 2 Selected bond distances (A) and angles (") for complexes 1, 2 and 8(a) Complex 1 aCu( 1 )-P( 1)Cu( 1 )-O( 1 )Cu( 1 a)-O( 1)N( 1 )-0(2)Fe( 1 )-C( 1-5)P(1)-Cu( 1)-P(2)P( 1)-Cu( 1)-O( 1 a)P(2)-Cu( 1)-O( la)Cu( 1)-O( 1)-Cu( 1 a)Cu( la)-O( 1)-N( 1)O( 1)-N( 1)-0(3)(b) Complex 2Cu( 1)-P( 1)Cu( 1)-O( 1)P( 1 t C ( 1)C(35)-O( 1)Fe( 1 t C ( 1-5)P( l t C u ( 1)-P(2)P( 1)-Cu( 1)-O(2a)P(2)-Cu( 1 )-O(2a)C( 3 5)-0(2)-Cu( 1 a)O( 1 )-C( 3 5)-0(2)CU( 1 )-P( 2)-C( 6)(c) Complex 8Cu(1)-I( 1)Cu(1a)-I(1)Cu( 1 )-P( 2)P(2)-C( 10)Fe( 1 )-C( 6- 1 0)P( 1)-Cu( 1)-P(2)P( 1)-Cu( 1)-I( 1)P(2)-Cu( 1)-I( 1)P(2)-Cu( 1)-I( la)Cu( I)--P(2)-C(lO)2.254(6)2.154(6)2.1 7 1 (6)1.268(14)2.023(9)(mean)117.8(1)100.3(3)130.3(4)104.9(3)126.6(7)119.6(7)2.276( 1)2.055(4)1.233(7)1.825(5)2.047( S)(mean)110.8( 1)109.3( 1)108.0( 1)130.1(6)13 1.4(4)109.1 (2)2.649( 6)2.736( 7)2.28( 1)1.81(4)2.046( 4)( mean)1 1 1.2(4)1 17.7(4)108.1(3)100.5(4)108(1)Cu( 1)-P(2)Cu( 1)-O( 1 a)N(1)-0(1)N(1 )-0(3)Fe( 1)-C(bl0)P( 1)-Cu( 1)-O( 1)P(2)-Cu( 1)-O( 1)O( 1 t N ( 1 )-W)0(2kN(1)-0(3)O( 1 bCu( 1 )-O( 1 a)CU( 1)-O( 1)-N( 1)Cu( 1)-P(2)Cu( 1 )-O(2a)C(35)-0(2)P(2)-C(6)Fe( 1 )-C(b 10)P( 1)-Cu( 1)-O( 1)P(2)-Cu( 1)-O( 1)O( 1 )-Cu( 1 )-O(2a)Cu( 1 )-O( 1)-c(35)Cu( 1)-P( 1)-C( 1)Cu( 1)-I( 1 a)Cu( 1)-P( 1)P( 1 )-C(5)Fe( 1)-C( 1-5)I(1)-Cu(1)-I(1a)P( 1)-Cu( 1)-I( 1 a)Cu( 1)-I( 1 )-Cu( 1 a)CU( 1)-P( 1)-C(5)Symmetry transformation: a -x, y , + - z.Symmetry transformation: a -x, -y, -z.2.263(6)2.1 7 1 (6)1.284( 13)1.227( 1 1)2.052(10)112.3(4)72.6(3)120.8(7)115.2(13)12239)11 5.4(3)2.243(2)2.1 1 l(4)1.2 1 O(6)1.820( 5)2.042( S)(mean)108.1( 1)121.5( 1)98.1 (2)124.4(3)1 16.0(2)2.736(7)2.286( 8)1.80(5)2.058(5)(mean)98.2(2)119.1(3)8 1.8(2)116(1)diphosphine such as dppf is generally assumed to be iso-structural. la Identification of the three structures demonstratesunequivocally that this is a risky, and in these cases, invalid,assumption. Thus [CU(NO,)(PP~,),],'~ [CUI(PP~,)~] 24 and[Cu(O,CH-O,O')(PPh,),] '' are all monomeric, but their dppfanalogues, 1,2 and 8, are dimeric.This difference can be tracedto the steric differences between the two ligands. In general,[Cu'XL,] complexes are monomeric unless X - sterically orelectronically favours bridge formation (e.g. SCN-'6 or N3-, ').Most are either trigonal planar (1 6 electron), when X- ismonodentate,28 or tetrahedral (1 8 electron), when X- isbidentate.,' When L is a monophosphine, [(Cu(pI)(PPh-H'),}' J 30 and [{Cu(p-I)(PMePh,),)2]~SOz31 are the onlycrystallographically proven dimers to date. Complex 8 isthe sole example of dimeric halogeno complexes of copper(1)diphosphines. Similar dimers among silver(1) complexes aremuch moreThe compounds dppm 3 3 and dppf 34 share many similaritiesand stabilize similar A-frame and related structures. Complexes1, 2 and 8 however demonstrate a notable difference betweendppm and dppf.The structures of both [Cu(O,CH)(dppm)]and [Cu(NO,)(dppm)] are unknown, but in the related com-d p ~ m ) ) , ] , ~ ~ H and [C~,(p~-Cl),(p-dppm),]Cl,~~ the dppm isbridging. The dppf in all the present copper(1) complexes ishowever chelating. The bonding mode adopted by dppf dependson the metal geometry. Despite the wide distribution of dppfchelates, these complexes are the first crystallographicallyplexes C{Ag(N0,-~,~')(CL-dPpm)),1,35 C{Ag(O,CMe-O,O')(p-characterized [{ CuX(L-L)},] complexes in which the diphos-phine (L-L) takes up the chelating mode. Similar behaviour hasbeen reported for dppm and dppe [Ph,P(CH,),PPh,] in[{Cu(O,CMe)(L-L)),] but lacks crystallographic support."Such a chelation tendency possibly precludes the formation of alinked structure such as [{Cu(p-I),Cu(~-dppf),),1 I.Com-plexes of Cu' on the contrary, containing bridging dppm areabundant.,* The structures of 1, 2 and 8 demonstrate for thefirst time the different co-ordination and structural preferencesamong dppf, dppm and PPh,, and will be useful markers for ourfuture design of copper(1) phosphine complexes.The monomeric structure in [CuI(PPh,),] is stabilized by alarge P-Cu-P angle [126.9(1)"], as expected for a bulkyphosphine. This angle is significantly reduced in 8 [l 1 1.2(4)"](Table 2) and the PPhH, analogue [117.0(l)"(mean)] (andcomplexes 1 and 2), but is only slightly higher than that in[{Cu(p-I)(PMePhZ),),]-SOz [125.4( l)"].Chelates of dppf havebeen found in all commonly known geometries. Among these,chelate bites which match closely the geometry angles inherentto the hybrid orbitals are found only in tetrahedral complexes(e.g. mean chelate angles in known ~quare-planar,,~ tetra-hedral 5,40 and trigonal-planar 4,7*9,10 dppf complexes are = 99,108 and 109" respectively). The near-ideal chelate angles foundin 2 [110.8(1)] and 8 [111.2(4)'] further support thisphenomenon. Based on these data, we may conclude thatchelating dppf is most comfortable in a tetrahedralenvironment. The large P-Cu-P chelate angle found in 1[ 1 17.8( l)"] is exceptional and interesting.It is in fact the larges3454 J. CHEM. SOC. DALTON TRANS. 1994Table 3 Crystallographic data and refinement details for [{Cu(~-NO,-O)(dppf-P,p)),I 1, [{CU(CC-O~CH-~,O')(~PP~-P~~)}~I 2 and [{CU-(p-I)(dppf-P,P')} 2]*2CH 2C12 8 *1 2 8M 1359.8 1325.8 1659.6Colour and habit Golden-yellow prism Yellow plate Golden irregular-shaped crystalTriclinic Crystal system Monoclinic TriclinicSpace group C2/c (no. 15) PT (no. 2) PT (no. 2)alA 20.173(4) 8.645( 1) 12.684(3)blA 12.767(3) 1 1.725(2) 12.807(3)CIA 24.355(5) 14.895(2) 1 3.876( 3)aio - 98.44( 1) 97.00(2)103.48(2) 103.90( 1) 114.06(2)- 96.62( 1) 1 1 1.78(2)01"rl"UjA3 6 loo( 3) 1431.7(3) I809.4(6)Z 4 1 1F(OO0) 2784 680 824DJg cm-3 1.48 1 1.538 1.52Standard reflectionsIntensity variation (%) + 1.1 + 1.1 f 1.0Rin, (from merging of equivalent reflections) 0.038 0.018 0.01 1Mean p r 0.15 0.10 0.1 1(2,0, - 81, (2,2,6), (6,0,2) (1 7 - 2, I), (1 ,o, 1) (2, - 2, - 61, (3, - 2, - 6)p1cm-l 13.14 1.394 20.9Crystal size/mm 0.40 x 0.38 x 0.42Transmission factors 0.640.86 0.74 1-0.98 1 0.056-0.2 140.06 x 0.22 x 0.28 0.06 x 0.08 x 0.10Scan rate/" min-' 3.00-60.00 2.00-29.30 3 .O- 1 4.6Collection range - 1 < h < 21, - 1 < k < 15, 0 < h < 10, -13 < k < 13, h, k k , + I-28 < I < 28 -17 < I < 172enlaxi" 45 50 45Observed data, nUnique data measured 5237 4483 2819No.of variables, p 33 1 187 140R 0.063 0.043 0.082R' 0.060 0.056 0.078S 1.73 1.44 1.72* Details in common: T294 K; scan range 0.80' below Kal to 0.80" above Ka2; stationary counts for one-fifth of scan time at each end of scan range;1738 C I F O I ' 3.0o(l~oI)l 3099 [IF01 ' 6.0~(lFoI)l 14 1 3 C I F O I ' 3.Oo(l~oI)lResidual extrema in final difference maple k3 + 0.53 to -0.47 +0.67 to -0.57 +0.62 to -0.43R = CllFoI - l ~ ~ l l l ~ l ~ o l ~ R' = l?w2(IFoI - I~c1)21~~21~0121+; s = Ccw(lF0I - IFc12)l(n - PI]+.Table 4 Atomic coordinates for complexes 1 ( x 10' for Cu, x lo4 for others), 2 ( x 10' for Cu and Fe, x lo4 for others) and 8 ( x lo4)Atom X(a) Complex 1-4 846(6)-1 101(4)- 546(3)- 1 093(3)-1 632(3)- 1 693(1)-711(3)- 1 I M(3)-1 636(3)(b) Complex 2CU( 1) 4 3 13(8)Fe( 1) 38 216(8)P(1) 1015(2)P(2) 1 170(2)C(1) 2 305(6)C(2) 3 922(6)C(3) 4 51 l(7)(34) 3 290(7)C(5) 1 901(6)(c) Complex 8I(1) 6 362(2)CU(1) 4 552(3)Fe( 1) 3 033(4)P(1) 3 107(7)P(2) 5 565(7)C(1) 1589(35)C(2) 1807(41)C(3) 3 llO(36)Y873(4)31(30)- 157(10)-214(8)170( 12)- 8(8)- 327(5)- 290(5)- 1 054(5)561(6)10 051(6)- 1 201(1)1914(1)- 557(4)535(4)- 727(4)-41(4)232(4)4 586(3)5 139(4)6 389(5)3 918(8)7 058(8)4 683(47)5 392(51)5 90 l(46)18 206(4)2 838(3)2 682(2)3 344(3)2 480(3)282( I )282(3)- 280(3)-331(3)35 546(4)22 207(4)2 410(1)3 436(1)1751(3)1 802(3)1214(3)787(3)1 118(3)Atom X-1 555(3)- 983(3)- 1 873(4)- 2 457(4)- 2 665(4)-2 210(4)-1 720(4)- 642(2)- 998(2)3 165(6)3 816(6)5 409(6)5 768(6)4 392(6)- 2 274(7)- 1 853(4)- 1 721V- 1 564(5)- 1 114(5)1 582(6)1 036(6)330(6)440(6)1214(6)- 1 406(3)1557(3)2 069(4)2 739(4)2 536(5)1 746(5)1445(4)- 464( 5)- 535(3)206(4)199(3)578(3)262(3)336(3)873(3)828(3)1313(1)1408(1)- 42( 3)3 225(3)2 645(3)2 702(3)3 323(3)3 648(3)4 376(4)3 638(2)5 116(3)4 901(2) C(4) 3 705(32) 5 375(42) 560(35)3 659(4) C(5) 2 777(27) 4 654(34) 835(31)1 179(4) C(6) 4 433(32) 8 112(41) 2 1 lO(37)3 730(7) C(8) 2 358(3 1) 7 376(41) 1834(34)183(40) C(9) 3 028(28) 6 890(37) 2 654(32)2 786(32) - 469(49) C( 10) 4 335(28) 7.389(35)1 860(7) C(7) 3 117(32) 8 028(41) 1444(39)- 2 16(40J. CHEM.SOC. DALTON TRANS. 1994R = H 2, Me 3, CF, 4, Et 5 or Ph 73455ip, PPhp= F P zLk PPh,C(13)Fig.2 (a) A perspective view of the molecular structure of [{Cu(p02CH-0,0')(dppf-p,p')),1 2. (b) Half of the molecule of 2 showing thelabelling scheme0B CDF P DADFever reported for dppf chelates for any metal in all geometries.Curiously perhaps, it is significantly larger than those found intrigonal-planar complexes, e.g. [Cu,(p-dppf)(dppf-P,P'),]-[C104]2,4 which together with 8 has the second largestdppf bite (1 11.2"). This may not be surprising when oneconsiders that even larger angles are found in other tetrahedralCuX(PR,), complexes. However, the phosphines in thesecomplexes are invariably sterically demanding, and the P-Cu-Pangles in monophosphine complexes are obviously notrestricted by any conformational strain which is inherent to achelate.The planarity of the Cu,O, and NO, entities isprobably a major contribution to this large bite angle.I7 Theisolation and identification of complex 1 remove any lingeringR rnP f d O W P ) \ / \O P6Scheme 1 (i)dppf; (ii)Pr"C02-;(iii) RCO,-;(iv) Idoubt that chelating dppf can support a geometry that requiresa bite larger than ~ 1 1 0 " for stabilization. To conclude,although a tetrahedral environment is the 'natural' choice forchelating dppf, the chelate angle of dppf is very sensitive to thenature of the supporting ligands. The ability of this diphosphineligand to adjust its chelating bite may be among the reasons whysome catalytic reactions are supported better by dppf than byother di- and mono-ph~sphines.~~ For monodentate phos3456 J.CHEM. SOC. DALTON TRANS. 1994Fig. 3 Molecular structure of [(CU(~-I)(~~~~-P,P')}~]*~CH,CI, 8 (solvent omitted)FC"CP) PGH Iphines, the P-M-P angle is not subject to any chelatingconstraint. These ligands are however more susceptible todissociation which could be detrimental to the stability of thecatalyst, and hence product yield.Addition of dppf to complex 1 readily gives [Cu,(NO,-O),-(p-dppf)(dppf-P,P'),] 9. The analogous silver(1) structure wasfound to be dimeric with a singly bridging dppf between twoAu(dppf) chelate rings and nitrate as an unco-ordinating anion(J). Infrared data for 9 conform to this bridged structure butv(NO,) is diagnostic of a unidentate nitrate. The differencebetween the two complexes is ascribed to the higher tendencyfor Cu' compared to Au' to adopt a higher co-ordinationnumber.A similar conclusion has been drawn in a crystal-lographic study of [Au(PP~,),]NO,.~~ The silver(r) analogueof 9 and the structure of its PF,- salt has been reportedrecently. loExperimentalGeneral.-All manipulations were routinely carried outunder a dry argon atmosphere using freshly distilled solvents.The instruments used have been previously reported.2a+Elemental analyses were performed by the MicroanalyticalLaboratory in the Chemistry Department in the NationalUniversity of Singapore. Molecular-weight measurements werecarried out by Galbraith Laboratories, Knoxville, TN, usingvapour-pressure osmometry with a Knaiier-Dampfdruckosmometer. Infrared spectra were recorded on samples preparedin KBr discs.All NMR samples were in CDCl, solutions.Syntheses. -[(Cu( p N 0 , - O)(dppf-P,P' )} ,3 1. The salt Cu-(NO3),-3H,O (0.217 g, 0.90 mmol) in MeOH (20 cm3) wastransferred dropwise via a Teflon delivery tube to atetrahydrofuran (thf) solution (20 cm3) of dppf (0.500 g, 0.90mmol). The reddish brown solution was stirred for 30 min, afterwhich the mixture was reduced in volume to ca. 10 cm3 invacuum. The yellow precipitate obtained was filtered off andrecrystallized from MeOH (0.33 g, 54%) (Found: C, 59.7; H,61 .O; H, 4.1; Cu, 9.3; Fe, 8.2; N, 2.1%); vmax(N03) 1459s, 1384sand 1280s cm-'; 6,4.21 (s, 8 H, C5H4), 4.36 (s, 8 H, C,H4) and7.42-7.60 (m, 40 H, Ph); 6, - 14.5(s).[{C?(p-O,CH-O, 0' )(dppf-P,P' )},I 2.An aqueous solution(3 cm ) of Na0,CH (0.047 g, 0.69 mmol) was delivered by aTeflon tube to a methanolic solution (30 cm3) of complex 1(0.070 g, 0.05 mmol). The solution was stirred for 18 h andconcentrated to give an orange precipitate. The solid obtainedwas recrystallized from CH,Cl,-hexane (0.049 g, 72%) (Found:C, 62.7; H, 4.5; Cu, 9.3; Fe, 8.7; P, 13.9. C7,H,,Cu2Fe,04P4requires C, 63.4; H, 4.4; Cu, 9.6; Fe, 8.4; P, 9.3%); M 1313(CH,Cl,); v,,,(HCO,) 1601s and 1346m cm-'; 6,4.21 (s, br, 8H,C,H4),4.33(m,8H,C5H4),7.34-7.78(m,40H,Ph)and8.67[(Cu(p-O,CR)(dppf-P,P')},] (R = Me 3, CF, 4, Et 5, Pr" 6or Ph 7). A similar method to that for complex 2 was used usingthe corresponding sodium salt of the carboxylate.Complex 3 (0.059 g, 85%) (Found: C, 63.7; H, 4.5; Cu, 8.9;Fe, 8.8; P, 13.4.C7,H6,CU,Fe,0,P4 requires C, 63.9; H, 4.6;Cu, 9.4; Fe, 8.3; P, 9.2%): v,,,(MeCO,) 1546s and 1400s cm-';6, 2.11 (s, 6 H, MeCO,), 4.20 (m, 8 H, C,H4), 4.29 (m, 8 H,C5H4) and 7.32-7.78 (m, 40 H, Ph); tip - 17.2(s).4.0; CU, 9.3; Fe, 8.6; N, 1.7. C68H56CU2Fe2N206P4 requires c ,(s, 2 H, HCO,); 6 p - 17.4(~)J. CHEM. SOC. DALTON TRANS. 1994 3457Complex 4 (0.070 g, 62%) (Found: C, 58.8; H, 3.8; Cu, 8.1;F, 7.5; Fe, 7.4; P, 12.0. C,oH,6Cu2Fe,04P, requires C, 59.2; H,3.9; Cu, 8.7; F, 7.8; Fe, 7.6; P, 8.5%): v,,,(CF,CO,) 1688s cm-';6, 4.23 (m, 8 H, C,H,), 4.35 (m, 8 H, C5H4) and 7.29-7.74(m, 40 H, Ph); 6, - 16.0(s).Cumplex 5 (0.084 g, 79%) (Found: C, 59.1; H, 4.4; Cu, 7.9; Fe,7.1; P, 8.3.C7,H70Cu,CI,Fe,0,P, requires C, 58.8; H, 4.6;Cu, 8.2; Fe, 7.2; P, 8.0%): v,,,(EtCO,) 1592s, 1567(sh) and1409m cm-'; 8, 1.20 (t, 6 H, CH,), 2.39 (9, 4 H, CH,), 4.21(m, 8 H, C,H,), 4.29 (m, 8 H, C,H,) and 7.32-7.78 (m, 40 H, Ph);Complex 6 (0.070 g, 89%) (Found: C, 64.6; H, 4.9; Cu, 8.0;Fe, 7.4; P, 8.9. C7,H70Cu,Fe,04P4 requires C, 64.7; H, 5.0; Cu,9.0; Fe, 7.9; P, 8.8%): M 699 (CH2C12); vmaX(PrCO2) 1540s and1396m cm-'; 6, 0.96 (t, 6 H, CH,), 1.68 (m, 4 H, CH,), 2.37(t, 4 H, CH,), 4.21 (m, 8 H, C,H,), 4.28 (m, 8 H, C5H4) and7.31-7.79 (m, 40 H, Ph); 8p - 17.4(s).Complex 7 (0.091 g, 80%) (Found: C, 61.5; H, 4.2; Cu, 7.1; Fe,7.0; P, 7.2. C,,H7,Cu2Fe,0,P, requires C, 61.6; H, 4.4; Cu, 7.8;Fe, 6.8; P, 7.6%): v,,,(PhC02): 1542s and 1396s cm-'; 6H 4.26(m, 8 H, C,H,), 4.31 (m, 8 H, C,H,) and 7.29-8.22 (m, 50 H, Ph);[{Cu(p-I)(dppf-P,P')],] 8.This complex was prepared by aprocedure similar to that for 2, from 1 (0.233 g, 0.171 mmol) andKI (ca. 0.06 g, 0.362 mmol). Yield 0.135 g (53%) (Found: C, 54.8;H, 3.6; c u , 9.0; Fe, 7.9; I, 17.2; P, 8.5. C68H56CU2Fe212P4requires C, 54.8; H, 3.8; Cu, 8.5; Fe, 7.5; I, 17.0; P, 8.3%); ljH 4.20(s, 8 H, C,H,), 4.34 (s, 8 H, C,H,) and 7.34-7.74 (m, 40 H, Ph);[Cu2(N03-O),(pdppf(dppf-P,P'),]=CH,C12-2H,0 9. Soliddppf (0.030 g, 0.05 mmol) was added to a methanolic solution(25 cm3) of complex 1 (0.073 g, 0.05 mmol). The mixture wasstirred until it was practically free from dppf (TLC). Theorange precipitate obtained on partial removal of the solventwas isolated and recrystallized from CH2C1,-hexane (0.094 g,91%).The solvent molecules present were identified by 'HNMR spectroscopy (Found: C, 60.6; H, 4.2; Cu, 5.9; Fe, 8.7; N,1.1; P, 9.9. C,,3H,,C~,Cu2Fe3N,0sP6 requires C, 60.8; H, 4.5;Cu, 6.2; Fe, 8.2; N, 1.4; P, 9.1%); v,,,(N03) 1418m and 1281scm-'; 6,4.07 (m, 12 H, C,H,); 4.25 (m, 12 H, C,H,) and 7.31-7.42 (m, 60 H, Ph); 6, - 13.1(s). Molar conductance A,,, 34.0R-' cm2 mol (CH2C12).6 p - 17.4(~).8 p - 17.4(~).6, - 19.36(~).ray Crystallographic Analyses.-Single crystals of [(Cu(p-02CH-0, O')(dppf-P,P')},], 2 and [(Cu(p-I)(dppf-P,P')},] 8were grown from CH2C12-hexane and [(Cu(p-NO3-O)(dppf-P,P')} 2 ] 1 from 1,2-dichIoroethane-hexane. Those suitable forX-ray diffraction were mounted on thin-walled Lindemannglass capillaries under an atmosphere of nitrogen.Intensity datawere measured on a Siemens P4 diffractometer with graphite-monochromatized Mo-Ka radiation (3, 0.710 73 A) using thevariable o-scan technique. Two standard reflections weremonitored after every 125 data measurements, showing onlysmall random variations. The raw data were processed with thelearnt-profile procedure,43 and absorption corrections wereapplied by fitting a pseudo-ellipsoid to the y-scan data forselected strong reflections over a range of 28 angles.,, All thestructures were solved with the Patterson superposition methodand subsequent Fourier-difference syntheses. The structureanalysis of complex 1 was more difficult than usual since directphase determination tended to place the molecule on acentrosymmetric site whereas it actually lies on a crystal-lographic C, axis.Reflections hkl with l odd were generallyweak since two molecules related by the c glide are alsoapproximately related by the translation c/2. All the non-hydrogen atoms in 2 and 8 were refined anisotropically.Hydrogen atoms of the organic ligands were generatedgeometrically (C-H 0.95 A), assigned appropriate isotropicthermal parameters, and allowed to ride on their parent carbonatoms. The four phenyl groups in the asymmetric unit weretreated as rigid groups. The other non-hydrogen atoms wererefined anisotropically, and the hydrogen atoms of thecyclopentadienyl groups included in structure-factor cal-culations with assigned isotropic thermal parameters. Allcomputations were performed with the SHELXTL PC programpackage.45 Analytical expressions of neutral-atom scatteringfactors were employed, and anomalous-dispersion correctionswere in~orporated.,~ Crystal data, data-collection parameters,and results of the analyses are listed in Table 3.Additional material available from the Cambridge Crystal-lographic Data Centre comprises H-atom coordinates, thermalparameters and remaining bond lengths and angles.AcknowledgementsThe authors acknowledge the National University of Singapore(NUS) (RP850030) and the Hong Kong University andPolytechnic Granting Committee Earmarked Grant (ResearchAcc.No. 221600010) for financial support and technicalassistance from the Department of Chemistry, NUS.We thankY. P. Leong for assistance in the preparation of this manuscript.S. P. N. acknowledges a scholarship award from the NUS.References1 (a) K. S. Gan and T. S. A. Hor, in Ferrocenes-From HomogeneousCatalysis to Materials Science, eds. A. Togni and T. 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ISSN:1477-9226    

DOI:10.1039/DT9940003451

出版商:RSC    

年代:1994

数据来源: RSC