摘要:

J. CHEM. SOC. DALTON TRANS. 1986 1753A Neutron Diffraction Study of [N(PPh,),]+[B,H,]-~CH,CI,t at 80 KSaeed 1. Khan, Michael Y. Chiang, and Robert Bau *Department of Chemistry, University of Southern California, L 0s Angeles, CA 90089, U.S.A.Thomas F. KoetzleChemistry Department, Brookhaven National Laboratory, Upton, NY 7 7973, U.S.A.Sheldon G. Shore and Steven H. LawrenceDepartment of Chemistry, Ohio State University, Columbus, Ohio 432 10, U.S.A.The structure of the [ B,H,] - anion, reported by us earlier in an X-ray structure determination, hasbeen analysed more accurately by neutron diffraction. Data were collected at 80 K on a sample of[N (PPh,),] + [ B,H,] -=CH,CI, using the Brookhaven High Flux Beam Reactor. The essential resultsof the X-ray analysis are confirmed, with more accurate molecular parameters.The [B,H,] - anionhas a non-crystallographic C, symmetry, with a bent geometry [B-H-B 127(2)"] and staggeredterminal B-H bonds. Average terminal and bridging B-H bond lengths are 1.1 8(2) and 1.27(6) Arespectively, and the B B distance is 2.27(1) A. There i s a slight asymmetry of the B-H-Bbridge [B(1 )-H 1.32(2), B(2)-H 1.21 (2) A], which is on the borderline of being significant.[N( PPh,),] + [B,H,] -*CH,CI, crystallizes in the triclinic space group P i , with a = 9.633(1),b = 10.513(1), c = 16.938(1) A, = 90.599(7), p = 93.142(8), y = 93.744(8)", and Z = 2 at 80 K.The final R factor is 0.096 for the 1 479 reflections with Fo2 > 3o(Fo2).In an earlier communication' we reported the results of anX-ray structural analysis on the [B,H,] - anion, which showeda bent, singly-bridged B-H-B bond with some asymmetry in theB-H distances of the bridging H atom [1.00(5) and 1.27(5) A].However, due to the relatively low precision in hydrogen atompositions, as is usual in X-ray studies, more definitiveconclusions regarding the nature of the B-H-B bridge could notbe made. We now report the results of a more accuratestructural determination on the [B2H7] - anion using neutrondiffraction.ExperimentalThe title compound was prepared according to a publishedprocedure.Crystals for neutron diffraction studies wereobtained as follows. An unweighed quantity of [N(PPh,),] +,-[B,H,]--CH,Cl, (20-50 mg) was placed into a round-bottomed tube sealed to a 9-mm Solv-Seal joint.This wasattached to a stopcock adapter and the assembly was evacuated,followed by addition of enough CH,Cl, completely to dissolvethe solid. After all the solid dissolved, the solution was cooled to- 78 "C and a diethyl ether-dichloromethane mixture (5: 1 v/v)was very slowly condensed onto the CH,Cl, solution so as toavoid premature mixing. The assembly was allowed to stand atroom temperature. Crystals large enough for neutrondiffraction studies were obtained in 4-7 d.As reported earlier,' crystals of [N(PPh,),] +[B2H7] - 0CH,Cl, show a pronounced tendency to lose molecules ofcrystallization (CH,CI,) in a dry atmosphere. Thus the crystalwas mounted under a nitrogen atmosphere in a glove-boxsaturated with CH,Cl,.Two of the best three samples werecoated with a thin film of Styrofoam (i.e. quickly dipped in at Bis(t ripheny1phosphine)iminium heptahydrodiborate-dichloro-methane ( I /I).Supplemenfury duru uuaifabfe (No. SUP 56561, 6 pp.): [B,H,] - least-squares plane and torsion angles, Ph group atom co-ordinates, thermalparameters. See Instructions for Authors, J. Chem. SOC., Dalton Trans.,1986, Issue 1 , pp. xvii-xx. Structure factors are available from theeditorial office.Table 1. Summary of crystal data and refinement results for[N(PPh,),] f[B,H,]-CH,CI, at 80 KSpace group Pib/ACIAM 652.2alA 9.633( 1)10.5 I3( 1)16.938( 1 )do 90.599( 7)Pi" 93.142(8)Y I" 93.744( 8)z 2u p 1 709(8)DJg ~ m - ~ 1.267p/cm-' 3.156Crystal dimensions (mm)Crystal volume (mm3) 2.38Neutron wavelength (A) 1.160 38(4)Total number of reflections measuredNumber of unique reflectionsNumber of variable parameters (n,)Final agreement factorsR(F2) = ClFo2 - k2Fc21/CFo2S = CwlFo2 - k2Fc2l2/(n0 - n,)2.0 x 0.7 x 1.7Crystal boundary faces(sin~)/h limit (A-')Number of reflections used in analysis (no)(010), W), (10% (101)0.494 (28 = 70")3 2772 90714791710.0960.1021.563R'(F2) = CwIFO2 - k2Fc212/C~Fo4~~~solution of Styrofoam dissolved in CH,Cl,), and the other onecoated with epoxy glue.Each of the crystals was then mountedon an aluminium pin and sealed in an aluminium can, togetherwith a piece of glass wool, soaked in CH,Cl, and placed at thebottom of the can.After initial screening, the selected sample(one of the Styrofoam-coated crystals), with the [TOO] axisapproximately parallel to the A1 pin, was placed in a closed-cycle helium refrigerator (Air Products DISPLEX CS-202)mounted on a four-circle diffractometer at the BrookhavenHigh Flux Beam Reactor. A germanium (220) single-crystalmonochromator was em loyed to obtain a neutron beam ofwavelength 1.160 38(4) 8: [based on KBr (a = 6.6000 A at295 K)]. Diffraction data were collected at 80.0(5) K with th1754 J. CHEM. SOC. DALTON TRANS. 1986temperature monitored by a Pt resistor which was calibratedagainst the magnetic phase transition at 78.38(1) K of an FeF,cry~tal.~ The unit-cell parameters at 80 K were determined byleast-squares procedures based on the (sin2@ values of 32reflections (50 < 28 < 607, and are listed in Table 1.Intensity measurements were carried out with an o step-scantechnique.The scan width was Am = 4.0” with 100 steps perscan. Counts were accumulated at each step for approximately3.5 s, the exact time interval being determined by monitoring theincident beam intensity. The intensities of three monitorreflections [(3,3,1 l), (5,0,0), (1,4,3)] were measured at 100-reflection intervals and showed no significant variation duringthe course of data collection.Integrated intensities were calculated by taking seven pointson either end of each scan as a measure of the background.Observed intensities were then corrected for absorption bynumerical integration over a Gaussian grid of points5 andconverted to squared structure factors, Fo2 = Isin28.Theminimum and maximum transmission coefficients were 0.626and 0.8 1 0 respectively. Altogether, 3 277 reflections weremeasured, which were then averaged for multiple observationsto give 2 907 independent values of Fo2.Structure Analysis.-The structure analysis was carried outwith data having Fo2 > 30(FO2) (1 479 reflections). Initialrefinement was carried out using differential synthesis with thestarting model defined by the non-hydrogen atoms from theX-ray analysis.’ All hydrogen atoms, including those of theanion, were located from subsequent difference scattering-density maps and positions were refined to convergence. Inorder to reduce the parameter-to-data ratio, the final least-squares refinement cycles were carried out using rigid-bodymethods.* The rigid-group parameters for the six phenylgroups of the cation were calculated using an idealizedgeometry (C-H 1.80 A, C-C 1.396 A).The 11 atoms of eachphenyl group were assigned individual isotropic thermalparameters. Least-squares refinement was carried out minimiz-ing the value Cw(Fo2 - k2F02)2 with weights defined asw = 1/c2, where o2 = [02,0U,t + (0.02 F02)2]. A total of 171parameters (a scale factor, positional and isotropic thermalparameters of 17 non-group atoms, and 102 group parameters)were refined to final agreement factors of R(F2) = 0.096 andR’(F2) = 0.102, A difference synthesis computed at this stagewas essentially featureless.The neutron scattering lengths usedwere (in units of cm): b, = 0.535, b, = 0.665,b, = -0.374, bN = 0.930, and b, = 0.519.Results and DiscussionThe final atomic parameters (excluding the phenyl rings) aregiven in Table 2. Selected bond lengths and angles are listed inTable 3; the group parameters are given in Table 4.The molecular structure of the [B,H7]- anion, with thenumbering scheme, is illustrated in Figure 1. The geometryaround each boron atom is a distorted tetrahedron with the sixterminal hydrogen atoms arranged in a staggered conformation.The displacements through a least-squares plane passingthrough the atoms H(l), B(l), H, B(2), and H(4) are listed inSUP 56561 as are the torsion angles describing the [B2H7]-conformation.The cation, [N(PPh,),J+, as usual, has a bent* The program used for the rigid-body refinement was UCIGLS, a ver-sion of ORFLS (W. R. Busing and H. A. Levy), modified by J. A. Ibersand R. J. Doedens. See R. J. Doedens, in ‘Crystallographic Computing,’ed. F. R. Ahmed, Munksgaard, Copenhagen, 1970, p. 198. Phenyl grouppositions were defined by (a) three angles which correspond to rotationsabout the central axes, and (b) the co-ordinates of the group centroid,giving six refined positional parameters for each phenyl ring.Table 2. Final positional ( x lo4) parameters for the non-group atoms of“(PPh,),l +CB2H71 -*CH,CI2X8 789(6)8 050( 10)10 255(10)-4 918(13)- 4 630( 13)- 4 227(25)- 3 963(27)- 5 668(27)- 5 429(26)- 5 821(21)-4 021(22)- 4 088(24)2 704( 10)2 142(22)3 526(21)3 382(7)1 524(7)Y4 867(5)3 455(9)5 543(9)2 893(11)769( 10)1850(23)3 609(24)2 855(23)3 01 l(23)488( 17)565(20)247(21)1225(8)480(20)1 670(18)4W6)2 367(6)27 523(3)7 465(5)7 316(6)2 962(7)2 843(6)3 045(14)3 122(14)3 503(15)2 341(15)2 765(10)2 266(13)3 436(13)I257(5)1 592(12)1640(11)961(4)446(4)H(1)Figure 1.Molecular plot of the [B2H7]- anion. The atoms are dis-played as 50% probability spheresstructure with a P-N-P angle of 136.7(6)”. The overall geometryof the anion as determined by neutron diffraction at 80K isessentially the same as that derived from the X-ray analysis at177 K.’(a) B-H Distances.-The most significant result of the presentanalysis is that the existence of the bent, singly-bridged B-H-Bbond is confirmed.The bridging hydrogen atom occupies aposition which is best described as marginally asymmetric (atthe 5.50 level), the two bridging distances being 1.32(2)[S(l )-HI and 1.21(2) A [B(2)-H]. The only other neutrondiffraction study reported for a boron hydride is on B,,H,,,*and interestingly in that analysis the bridging hydrogen atomswere also asymmetric, with average bond lengths of 1.298(5)and 1.347(7) A. (However, it should be pointed out that inB10H14 the boron atoms of the B-H-B bridges are chemicallyinequivalent.) A compound with a singly-bridged BH, group,[Cu(PPh,Me),(BH,) 1, has also been investigated with neutrondiffraction, but has a B-H bridging distance of 1.170(5) A,somewhat shorter than those found here.As has been pointedout earlier,’ if we accept the asymmetry of the B-H-B bridge in[B,H,] - to be significant, a chemically intuitive explanationcould be a donor-acceptor interaction between the two halvesof the anion: i.e. [BH,] -+BH,.The mean terminal B-H distance of the anion is in goodagreement with the other boron hydrides and metal boratecomplexes for which accurate B-H distances are available fromneutron diffraction and other spectroscopic methods (see Table5). However, one of the terminal B-H distances in the [B2H7] J. CHEM. SOC. DALTON TRANS. 1986 1755Table 3. Selected bond distances (A) and angles (") in [N(PPh,),J+-[B,H,J -*CH2C122.27( 1) B(2)-H(6) 1.25(2)1.32(2) P(l)-N 1.60(1)1.16(2) P(2)-N 1.59( 1)1.19(2) Cl(l)-C 1.76(1)1.14(2) C1(2)-C 1.76( 1)1.2 l(2) H(sl)-C 1.10(2)1.19(2)1.16(2) H(s2)-C 1.07(2)B(l)-H-B(2) 127.2(20)H(l)-B(l)-H(2) 108.8(18)H(l)-B(l)-H(3) 114.6(19)H(2)-B(l)-H(3) 117.0(20)H-B(lkH(1) 95.8(18)H-B(lFH(2) 103.7(17)H-B(l jH(3) 114.1(18)H(4)-B(2)-H(5) 113.1(15)H(4)-B(2)-H(6) 1 1 1.3(16)H(5)-B(2)-H(6) 110.9(17)H-B(2)-H(4)H-B( 2)-H( 5)H-B(2)-H(6)P( 1 )-N-P(2)C1( l)-C-H(sl)C1( l)-C-H(s2)C1(2)-C-H(sl)C1(2)-C-H(s2)H(s l)-C-H(s2)C1( l)-C-C1(2)1 19.9( 17)1O4.6( 17)95.4( 16)136.7(6)112.3(5)107.0( 12)1 11.0( 12)108.4(13)1093 12)108.3(16)anion is significantly longer [1.25(2) A ] than the other five[average 1.17( 1) A].A similar observation has been reportedfor the neutron structure of [Cu(PPh,Me),(BH,)], where oneof the B-H bonds is significantly longer [1.330(6) A] than theother three [average 1.179(5) A]. The thermal parameters ofH( I), H(2), and H(3) are somewhat larger than those for H(4),H(5), and H(6), and this may imply some sort of minor disorderin the packing of the molecules. Attempts to resolve anydisorder with the present data set were not successful.As far as B-H-B and M-H-B angles are concerned, the datafrom Table 5 clearly indicate that singly-bridged linkagesproduce angles substantially larger than those of the othermolecules listed.(6) The Three-centre Two-electron Bond in [B,H,]-.-Forthe past several years, neutron diffraction analyses lo carried outby our group and others on molecules containing unsupported*three-centre two-electron (3c-2e) bonds have suggested that thenature of such interactions is 'closed'.t Thus, systems contain-ing M-H-M { e.g., [W,H(CO),(NO)], [W,H(CO),,], etc.} ''and M-H-B linkages (e.g., [CU(PP~,M~),(BH,)])~ haveinvariably shown that the bridging hydride is not only bent butalso off-axis (see below). In this respect the B-H-B bond in[B2H7]- offers the simplest and perhaps the best example forprobing the details of 3c-2e bonds.The present result, asexpected, shows that the B-H-B linkage in [B2H7]- is againbent (B-H-B 127.2") and 'closed', i.e. the bridging hydride issignificantly displaced (average 18") off the pseudo-three-foldaxis defined by each terminal BH, group (see Figure 2).This canalso be seen from the fact that, although the H,-B-H, angles(t = terminal) are reasonably close to being tetrahedral [range108.8(18)-117.0(20)"], the Hb-B-HI angles (b = bridging)show considerable scatter [range 95.4(16)-119.9(17)"]. Thesame phenomenon was pointed out earlier in [Cu(PPh,-Me)3(BH,)].9 This observation implies the existence of asignificant amount of B-B interaction in the title compound.* We define a molecule having an unsupported 3c-2e bond as one inwhich the two halves of the molecule are held together solely by one 3c-2e bond, without other bridging groups. Thus, molecules such as B,H,or [Re,H,(CO),], which have two X-H-X bridges, are not included bythis definition.t A 'closed' 3c-2e bond is one in which all three orbitals overlap in acommon region of space; in the case of the B-H-B bond this would meanthat there is a significant amount of B-B bonding as well as B-H bonding.HnHFigure 2.Schematic diagrams showing that the B-H-B bridge is notonly bent but also 'off-axis' (see text). The displacement of the bridgingH atom off the local C, axis of each BH, fragment averages to ca. 18".This is interpreted as evidence that the B-H-B bond is of the 'closed'tYPe(c) Theoretical Studies on the [B2H7]- Anion.-In the past,the [B2H7]- anion has been a target of several theoreticalinvestigations probing the details of the 3c-2e bond. Earlier abinitio calculations had suggested that the central B-H-Blinkage would be linear." In contrast, a more sophisticatedtheoretical calculation of the isoelectronic [C,H,] + cationpredicted a bent central C-H-C backbone.', The results fromour X-ray diffraction analysis' on [B,H,]- showed aconsiderably bent B-H-B bond [B-H-B 136(4)"], consistentwith the results for [C,H,] +.The apparent inconsistencybetween the experimental and theoretical results for [B2H7] -led Raghavachari et a1.I3 to reinvestigate the [B2H7] - systemwith a higher level of optimization than employed for previouscalculations. The results of this most recent analysis showed thecentral B-H-B bond to be bent with a B-H-B angle of 126.4", avalue which compares very well with the present neutrondiffraction result [B-H-B 127.2(20)"]. Finally, another recentab initio calculation by Sapse and Osorio has also concludedthat the central B-H-B backbone is bent, but with an angle of149.9'.Significant differences, however, still remain between theexperimental and theoretical results.The observed B-B andB-H distances are all shorter than their calculated values.Perhaps more importantly, all theoretical calculations predict asymmetric B-H-B bond. Indeed, experimental results on[Me,Al-H-AlMe,] - and theoretical calculations on[H,Al-H-AlH,]- l6 both show a symmetric and linearAl-H-A1 bond. In the [B2H7] - case, although the experimentalresults reported here show the B-H-B bond to be much lessasymmetrical than was the case in the earlier X-ray work'[B-Hb 1.27(5), l.OO(5) A], the current neutron values still showasymmetry [B-H, 1.32(2), 1.21(2) A; difference 5.501.One caninterpret this as being due to a partial contribution from a'donor-acceptor' type of interaction in the B-H-B bridge (seeabove). Alternatively, one might argue that the asymmetry weobserve is an artifact arising from disorder or crystal-packingeffects (i.e. non-equivalent environments around two ends of the[B2H7] - anion in the crystal lattice), but there are no unusuallyshort non-bonded contacts to support this latter contention(minimum H H 2.02 A). We intend to continue studying thisproblem by structurally investigating other salts of [B,H,] -and its derivatives (such as [Ph,B-H-BPh,] -).AcknowledgementsResearch at Brookhaven National Laboratory was carried ou1756 J.CHEM. SOC. DALTON TRANS. 1986Table 4. Refined group parameters* of the phenyl ringsGroup 1 Group 2 Group 3 Group 4 Group 5 Group 62 716(2) 3 436(2) 1397(2) 6 384(2) 3 736(2) 8 055(2)1 042 5 745(1) 8 541(1) 8 132(1) 8 939(1) 6 264(1) 6 344(1)cpl" -0.8(1) - 9.8( 1) - 115.1(3) 149.5( 1) - 103.1(1) 89.1 (1)P/" 64.7(1) - 37.4( 1) - 109.5(3) - 72.2( 1) 121.9(1) 148.0( 1)* The definitions of the orientation angles, cp, 0, and p, are given by R. J. Doedens, in 'Crystallographic Computing,' ed. F. R. Ahmed, Munksgaard,Copenhagen, 1970, pp. 198-200.1 0 4 ~ 6 720(3) 5 416(3) 10 094(3) 11 940(3) 11 968(3) 9 704(3)1 0 4 ~- 134.0( 1) - 159.9( 1) ela 166.3( 1) - 170.4( 1) 111.0(1) - 151.43(6)Table 5. A Comparison of B-B and B-H distances in various boron-containing molecules for which accurate measurements are availableBoron hydrides and substituted boron hydridesCompound Method" B-B (A)B2H6 E 1.775(3)B2H5CH3 M 1.82(2)B2H5NH2 M 1.916(2)B,H,NMe, M 1.916(4)B4H10 M 1.854(2)1.718(2)B5H9 M 1.803(2)1.690( 2)B6H10 M 1.818(4), 1.77(1)1.710(6), 1.762(4)1.654(3), 1.783(1)B10H14i N 1.775( 5)CB,H,I - N 2.27( 1)B-WA1.196(8)1.195(9)1.187(5)1.20( 1)1.193(1)1.19 l(3)1.1832)1.180(4)1.1 7( 2)B-HbIA1.339(6)1.34(6)1.355( 5)1.365(6)1.42( 2)1.352(4)1.298(5)'1.3 47( 7)1.2 1 (2)1.32(2)B-H-BIO Ref.83.0 bC90.0(6) d89.1(9) ef84.3 (4) 8127(2) kMetal borate complexesCompound Method" B-H,/A B-Hb/A M-HbIA M-BIA M-H-B/" Ref.[U(BH4),1' N 1.24(3) 1.23(3) 2.34(2) 2.52( 1) 83U) m[U(BH4)4] " N 1.24( 3) 1.25(4) 2.41(2) 2.86(2) 98(1) m[Hf(BH&] ' N 1.15(2) 1.23( 1) 2.13(1) 2.28( 1) 80.6(6) 0[Hf(rl-c,H,Me),(BH4)21 "cCo(terPY)(BH,)l n,q N 1.22(1) 1.29( 1) 1.72(2) 2.15(1) 90.0(8) r96.8(5) PCCu(PPh,Me),(BH,)I N 1.23(5) 1.170(5) 1.697(5) 2.5 18(3) 121.7(4) 91.19(1) 1.23( 1) 2.09( 1) 2.5 5 3 (6)" E = Electron diffraction, M = microwave spectroscopy, N = neutron diffraction.L. S. Bartell and B. L. Carroll, J. Chem. Phys., 1965, 42,1135. ' C. W. Chiu, A. B. Burg, and R. A. Beaudet, Inorg. Chem., 1982,21, 1204. K. K. Lau, A. B. Burg, and R. A. Beaudet, Inorg. Chem., 1974, 13,2787. E. A. Cohen and R. A. Beaudet, Inorg. Chem., 1973, 12, 1570. N. P. C. Simmons, A. B. Burg, and R. A.Beaudet, Inorg. Chem., 1981, 20,533. D. Schwoch, A. B. Burg, and R. A. Beaudet, Inorg. Chem., 1977, 16, 3219. D. Schwoch, B. Don, A. B. Burg, and R. A. Beaudet, J. Chem.Phys., 1979, 83, 1465. Measurement performed on a deuteriated sample (B10D14). J Asymmetrically-bridging hydrogen atoms. This work.E. R. Bernstein, W. C. Hamilton, T. A. Keiderling, S. J. La Placa, S. J. Lippard, and J. J. Mayerle, Znorg.Chem., 1972, 11, 3009. Doubly bridging BH, unit, i.e. M(p-H),BH,. T. J. Marks and J. M. Williams, personal communication, 1978. P. L.Johnson, S. A. Cohen, T. J. Marks, and J. M. Williams, J. Am. Chem. SOC., 1978, 10,2709. terpy = 2,2':6',2"-terpyridyl. E. J. Corey, N. J. Cooper,W. M. Canning, W. H. Lipscomb, and T. F. Koetzle, Inorg. Chem., 1982, 21, 192.Singly bridging BH, unit, i.e. M(p-H)BH,.Triply bridging BH, unit, i.e. M(p-H),BH.under contract to the U.S. Department of Energy and alsosupported by N.S.F. (to R. B.) and U.S. Army Research Officegrants (to S. G. S.). In addition, stimulating discussions withProfessor Paul v. R. Schleyer of the University of Erlangen/Niirnberg and the technical assistance of Mr. Joseph Henriquesduring neutron data collection are gratefully acknowledged.ReferencesI S. G. Shore, S. H. Lawrence, M. I. Watkins, and R. Bau, J. Am. Chem.Soc., 1982, 104, 7669.2 R. K. Hertz, H. D. Johnson, 11, and S. G. Shore, Znorg. Chem., 1973,12, 1875; 1977, 17, 24.3 R. K. McMullan, L. C. Andrews, T. F. Koetzle, F. Reidinger, R.Thomas, and G. J. B. Williams, NEXDAS, Neutron and X-Ray DataAcquisition System, unpublished work; D.G. Dimmler, N.Greenlaw, M. A. Kelley, D. W. Potter, S. Rankowitz, and F. W.Stubblefield, IEEE Trans. Nucl. Sci., 1976, 23, 398.4 M. T. Hutchings, M. P. Schulhof, and H. J. Guggenheim, Phys. Ren.B, 1972, 150.5 W. R. Busing and H. A. Levy, Acta Crystallogr., 1957, 10, 180.6 Program DIFSYN, R. K. McMullan, Brookhaven National7 L. Koester, H. Rauch, M. Herkens, and K. Schroder, Kernfor-8 A. Tippe and W. C. Hamilton, Znorg. Chem., 1969, 8, 464.9 F. Takusagawa, A. Fumagalli, T. F. Koetzle, S. G. Shore, T.Schmitkons, A. V. Fratini, K. W. Morse, C. Y. Wei, and R. Bau, J.Am. Chem. Soc., 1981, 103, 5165.10 R. Bau and T. F. Koetzle, Pure Appl. Chem., 1978, 50, 55; R. Bau,R. G. Teller, S. W. Kirtley, and T. F. Koetzle, Acc. Chern. Res., 1979,12, 176.11 J. H. Hall, jun., D. S. Marynick, and W. N. Lipscomb, Inorg. Chem.,Laboratory, New York, unpublished work.schungsanlage Report, Julich, 198 1, 1755J. CHEM. SOC. DALTON TRANS. 1986 17571972, 11, 3126; C. Hoheisel and W. Kutzelnigg, J. Am. Chem. Soc.,1975,97, 6970; B. Bigot, R. M. Lequan, and A. Devaquet, Nouv. J.Chim., 1978,2,449; R. A. Whiteside, M. J. Frisch, J. S. Binkley, D. J.DeFrees, H. B. Schlegel, K. Raghavachari, and J. A. Pople, in‘Carnegie-Mellon Quantum Chemistry Archive,’ 2nd edn., July 198 1;J. S. Binkley. J. A. Pople, and W. Hehre, J. Am. Chem. Soc., 1980,102,939.12 K. Raghavachari, R. A. Whiteside, J. A. Pople, and P. v. R. Schleyer,J. Am. Chem. Suc., 1981, 103, 5647.13 K. Raghavachari, P. v. R. Schleyer, and G. W. Spitznagel, J. Am.14 A. M. Sapse and L. Osorio, Inorg. Chem., 1984, 23, 627.15 J. L. Atwood, D. C. Hrncir, R. D. Rogers, and J. A. K. Howard, J.16 J. M. Howell, A. M. Sapse, E. Singman, and G. Snyder, J. Am. Chem.Chem. SOC., 1983, 105, 5917.Am. Chem. SOC., 1981, 103, 6787.SOC., 1982, 104, 4758.Received 29th April 1985; Puper 5169

ISSN:1477-9226    

DOI:10.1039/DT9860001753

出版商:RSC    

年代:1986

数据来源: RSC