1,1,1,1 -Tetrakis[triorganylphosphineaurio(I)]ethanium(+) Tetrafluoroborates - Hypercoordinated Species Containing [H3C-C(AuL)4I+ Cations Oliver Steigeimann, Peter Bissinger, and Hubert Schmidbaur* Anorganisch-chemisches Institut der Technischen Universität München, Lichtenbergstraße 4, D-W-8046 Garching Z. Naturforsch. 48b, 72-78 (1993); received September 10, 1992 Auriophilicity, Gold(I) Phosphine Complexes, Ethane-tetraaurio(I) Compounds, X-Ray

Hypercoordinate, tetraaurated carbon-complexes of the type [H 3C -C (A uP R 3)4]+BF4~, R = Ph (1), R = C6H u (2), (PR3)2 = l,2-C 6H4(CH 2CH 2PPh 2)2 (3) have been prepared by the reac­ tion of the appropriate (phosphane)gold(I) chlorides with l,l,l-tris(dimethoxyboryl)ethane H 3C -C [B(O M e)2]3 in the presence of CsF. The products have been characterized by standard analytical and spectroscopic methods, including single crystal X-ray analyses of 1 and 2. In each case the pentacoordinated carbon atoms have been located at the centre of a square pyr- amide built up by a methyl group at the apex and four gold atoms forming the base with short Au ••• Au distances of about 2.85 A, which strongly contribute to the formation and stability of these species.

Introduction The special position of gold in the Periodic gation of complex units L -A u-X of phosphane Table is largely based on relativistic effects [1], gold compounds [3], but also to a clustering of which modify significantly the properties of the gold(I) atoms at or around a main group element valence electrons of Post-Lanthanide elements. like carbon, nitrogen, phosphorus, arsenic, oxy­ The relativistic contraction of the 6 s orbitals of the gen, sulfur, and selenium [4-10]. Apart from spe­ heavy elements reaches a pronounced local maxi­ cies with a more conventional stoichiometry mum for gold and leads to a break-up of the 5d 10 [(AuL)3E]+ (E = O [8], S [9a], Se [10a]), closed shell of electrons in the Au(I) oxidation [(AuL)4N]+ [5a-c,7], [(AuL)3NR]+ [5e-g], state. A wealth of evidence has been obtained from [(AuL)3PR ]+ [6], or C (A uL )4 [6c], novel cations structural and spectroscopic studies of both mono- [(AuL)4As]+ [7] with a nonclassical square-pyrami- and polynuclear gold(I) compounds for the exist­ dal structure and the unprecedented hypercoor­ ence of the resulting metal-metal bonding between dinated cations [(AuL) 5C]+ [4d], [(AuL)6C]2+ Au+ centers [2], Intra- and intermolecular metal- [4c, e-h], [(AuL) 5N]2+ [5d], and [(AuL) 5P]2+ [6 a] metal interactions give rise not only to the aggre­ have been discovered.

r— — 2 + — _ n+ — L Au Au R 1 ..-A u L 1 ,,-A u L 1 LAu — X '' x LA u^ | "'^AuL | ^ * A u L LAu'"^ \^"'AuL Au Au LAu AuL L _ _ _ _

B: X = C, n = 1 E: X = C, n = 1 C: X = N, n = 2 F: X = P, n = 2 D: X = P, n = 2

* Reprint requests to Prof. Dr. H. Schmidbaur. While the number of homoleptic species A -D with the interstitial atom in the center of trigonal Verlag der Zeitschrift für Naturforschung, D-W-7400 Tübingen bipyramids or octahedra of gold atoms has been 0932-0776/93/0100-0072/$ 01.00/0 steadily increasing, only two examples are known

Dieses Werk wurde im Jahr 2013 vom Verlag Zeitschrift für Naturforschung This work has been digitalized and published in 2013 by Verlag Zeitschrift in Zusammenarbeit mit der Max-Planck-Gesellschaft zur Förderung der für Naturforschung in cooperation with the Max Planck Society for the Wissenschaften e.V. digitalisiert und unter folgender Lizenz veröffentlicht: Advancement of Science under a Creative Commons Attribution Creative Commons Namensnennung 4.0 Lizenz. 4.0 International License. O. Steigeimann et al. • Tetraaurio(I) Complexes 73 to date where the coordination sphere around the from the reaction of 1,1, 1-trichloromethane and hypercoordinate central atom contains also a non­ ClB(OM e)2 with lithium powder in tetrahydro- gold substituent (E,F): These two dications furan, as described by Matteson et al. [11], the [RP(AuL)4]2+ [6 b] (R = o-tolyl) and (dimeric) analogous reaction led to the title compounds. The [RC(AuL)4]+ [4 b] (R = oxazolinyl) feature square gold(I) chloride complexes of PPh3, P(C 6H ,,)3 and pyramidal structures with, respectively, phospho­ l,2-C6H 4(CH 2CH 2PPh 2)2 required, were readily rus or carbon at the center, the R substituent at the available via published methods [ 12, 13, 4 e]. apex, and the four gold atoms at the base of the Treatment of the individual (phosphine)gold(I) polyhedron, with short Au-- Au contacts, indica­ chloride with l,l,l-tris(dimethoxyboryl)ethane in tive of the origin of this unusual clustering of gold the presence of cesium fluoride in hexamethyl- in both cases. phosphoric triamide (HMPT) produced yellow We now report on simple compounds with solutions. After filtration and precipitation with five-coordinated carbon atoms in cationic pentane/benzene crystalline complexes CH 3-C [A u P R 3]4 units. [H3C -C (A u P P h 3)4]+BF4- (1), [H3C -C (A u P { C 6H u }3)4]+BF4- (2) and Results [H3C -C ({ A u P P h 2CH 2CH 2}2C 6H 4)2]+BF4- (3) In preceding work tetrakis(dimethoxyboryl)- were obtained. methane C[B(OMe )2]4 and bis(dimethoxyboryl)- The products 1, 2 (yellow) and 3 (colourless) are m ethane H 2C[B(OM e)2]2 were found to be excel­ airstable, hygroscopic substances, insoluble in lent starting materials for the synthesis of highly non-polar solvents like pentane, slightly soluble in aurated homoleptic carbon centered clusters [4 c, benzene and readily soluble in dichloromethane or d, e-h]. Thus, the reactions of C[B(OMe )2]4 with HMPT. The compounds decompose on melting. (triorganylphosphine)gold(I) chlorides LAuCl in Characterization is achieved by elemental analysis, the presence of CsF lead to the formation of hy­ mass spectrometry and NMR spectroscopy. The percoordinated hexakis(phosphineaurio(I))-meth- data are summarized in the Experimental Section. anium(2+) dications of the type [(AuL) 6C]2+. The The existence of the hypercoordinated species degree of auration could be reduced from six to [CH3-C(A uPR3)4]+ was first established by high- five and four by the use of gold chloride complexes resolution field desorption (FD) mass spectrosco­ with bulky phosphanes [6 c], py. In the mass spectral studies the parent peaks at When l,l,l-tris(dimethoxyboryl)ethane was m /z = 1864.7 (1), 1936.1 (2), and 1821.1 (3) can chosen as the precursor, which is readily obtained readily be assigned to the appropriate cations.

CH + 4 RjPAuCI. + 4 CsF H3C -C[B (O M e)2]3 b f 4- - 4 CsCI, - 2 (MeO)jB R p ^ A u " - / \~ " A u . ‘ PR-i 3 Au Au / \ Ph2 RjP PR3 + 4 CsF PAuCI

- 4 CsCI 1 : R = Ph - 2 (MeO)3B ocx.Ph, 2 : R = c—C6H„

b f 4~ 74 Q. Steigeimann et al. • Tetraaurio(I) Complexes

Table I. {'H}3IP NMR chemical shifts 6 [ppm] for com­ are also in good agreement with that found for pounds R3PAuCl and [CH 3-C (A uP R 3)4]BF4. (H 3C)3C -A u P P h 3 (V HP = 6.5 Hz). In the {'H}13C NMR spectrum of p r 3 R3PAuC1 [CH3C(AuPR3)4]BF4 [H3C -C (A u P P h 3)4]BF4 the resonances of the PPh-, 33.4 32.1 phenyl carbon atoms show a pattern also common P(C6H n )3 54.9 49.5 for homoleptic carbon centered gold cluster '/2(Ph,PCH,CH,) 2C6H4 29.2 27.5 cations. The doublet for the ipso C atom is shifted downfield as compared to the corresponding reso­ nance in Ph 3PAuCl, whereas the other phenyl sig­ The {'H } 3IP-NMR spectra at room temperature nals are largely unchanged. The o- and w-carbon of compounds 1 -3 in dichloromethane-d 2 show atoms give rise to centered doublets caused by long one sharp singlet resonance in each case, which is range P-P ' coupling. The resonance of the termi­ not only indicative of a virtual fourfold symmetry nal H3C group appears as a singlet at Ö = 28.2 ppm. of the cations of 1 and 2, but also demonstrates the The signal of the interstitial carbon could not be equivalence of the ligand halves in the chelated detected, and partial enrichment with ,3C will cation of 3. When compared to the data of the cor­ probably be necessary for a direct observation of responding (phosphine)gold(I) chlorides, upfield the nucleus, a procedure already successfully ap­ shifts can be stated (Table I), as already reported plied for the [C(AuL)6]:+ species [4f], for the conversion of (phosphine)gold(I) com­ pounds to homoleptic hypercoordinated species Crystal Structure Determinations [(AuL)5C]+ [4d], [(AuL)6C]2+ [ 4 c , e-h]. The equi­ valence of the LAu units is further established by Because of strong crystal disorder in all samples the number and multiplicity of the signals in the ’H of 1 so far investigated, only the C -C (A u-P )4 NMR spectra. Besides the resonances of the (phos- skeleton could be determined for the cation in phine) ligands, symmetrical 1:4:6:4:1 quintets [H3C -C (A u P P h 3)4]BF4, which crystallizes in the could be observed for the methyl hydrogen atoms at triclinic space group P i with two stoichiometric ö = 3.55 (1), 3.22 (2) and 3.65 ppm (3) due to a VHP equivalents in the unit cell excluding any crystallo- coupling with the phosphorus atoms of the phos- graphical symmetry for the individual cation. Nev­ phines (Fig. 1). The signals appear in a region down- ertheless, by using a split model and refining field from the resonances of /^-hydrogen atoms in al- A u-P moieties at two positions, the coordination kylgold(I) complexes like (H 3C)3CAuPPh 3 (ö = 1.97 geometry at the interstitial carbon atom could be ppm) [14] attesting a deshielding with an increas­ established beyond any doubt. The penta-coordi- ing degree of auration. The absolute values of the nated cluster C atom is capping a square of gold coupling constants V HP (between 4.3 and 4.7 Hz) atoms and is associated with an apical methyl group (Fig. 2). The structure solution is a prelimi­ nary result.

Fig. 1. Quintet CH 3 resonance in th e 'H NM R spectrum Fig. 2. Structure of the C -C [A uP ]4 framework in the of[H 3C -C (A uPP h 3)4]BF4 (l) in CD 2C12. cation of 1 (ORTEP. arbitrary radii). O. Steigeimann et al. • Tetraaurio(I) Complexes 75

The resulting tetragonal-pyramidal environ­ Table II. (Fortsetzung). ment of the central carbon atom was fully con­ Atom x/a y/b z/c U(eq.) firmed, however, for the [H3C -C (A u P { C 6H n }3)4]+ cation in 2, which crys­ C 131 0.237(3) 0.668(3) 0.301(2) 0.072 0.309(2) 0.323(2) 0.062 tallizes in the triclinic space group P i with two for­ C 132 0.592(3) C 133 0.392(3) 0.630(3) 0.337(3) 0.092 mula units in the unit cell. The carbon-carbon C 134 0.375(3) 0.680(3) 0.399(3) 0.087 bond distance center-apex corresponds to a stand­ C 135 0.304(3) 0.756(3) 0.382(2) 0.084 ard C -C single bond. The average A u-C -A u an­ C l 36 0.218(3) 0.719(3) 0.365(2) 0.081 C 211 -0.194(2) 0.581(3) 0.194(2) 0.062 gle of 83° and gold-carbon distances between 2.14 C212 -0.129(3) 0.636(3) 0.136(3) 0.097 and 2.19Ä give rise to short intramolecular C213 -0.067(4) 0.570(4) 0.098(3) 0.114 Au-"Au contacts of 2.816Ä (average). The local C214 -0.134(4) 0.507(4) 0.078(3) 0.118 -0.183(4) 0.456(4) 0.130(3) 0.113 geometrical situation at the interstitial cluster C215 C216 -0.242(3) 0.523(3) 0.162(3) 0.097 atom is thus comparable to that found for the cen­ C 221 -0.302(2) 0.590(2) 0.319(2) 0.059 tral carbon atom in the C 222 -0.354(3) 0.654(3) 0.361(2) 0.083 [Au(oxazolinyl)C(AuPPh3)3]22^ dication [4b], The C223 -0.398(2) 0.586(3) 0.429(2) 0.063 C224 -0.319(3) 0.549(3) 0.477(3) 0.099 increasing sterical demand of the tricyclohexyl- C225 -0.266(3) 0.481(3) 0.435(3) 0.093 phosphine ligands in 1 as compared to the PPh 3 C226 -0.225(3) 0.534(3) 0.362(2) 0.070 substituents in the oxazolinyl complex is reflected C231 -0.348(3) 0.721(3) 0.195(2) 0.067 C232 -0.421(3) 0.657(3) 0.189(2) 0.083 in an elongation of the A u-P bonds (average C233 -0.501(4) 0.725(4) 0.150(3) 0.111 2.30Ä vs. 2.26Ä) and in larger deviations of the C234 -0.465(4) 0.775(4) 0.088(3) 0.119 C -A u -P angles (average 169.9° vs. 175.0°) from C235 -0.402(4) 0.841(4) 0.104(3) 0.111 0.108 linearity. C236 -0.319(4) 0.775(4) 0.132(3) C311 0.143(3) 1.065(3) 0.326(2) 0.066 Fractional atomic coordinates and equivalent C312 0.188(3) 0.986(3) 0.372(2) 0.074 isotropic displacement parameters for 2 are given C313 0.224(3) 1.017(3) 0.432(3) 0.099 in Table II, selected structural parameters in the C314 0.134(4) 1.041(4) 0.480(3) 0.129 C315 0.088(4) 1.113(4) 0.440(3) 0.115 cation to Fig. 3 [15]. C316 0.061(3) 1.101(3) 0.372(3) 0.088 C321 0.195(2) 1.018(3) 0.193(2) 0.063 C322 0.276(2) 1.067(3) 0.203(2) 0.063 Table II. Fractional atomic coordinates and equivalent C323 0.347(5) 1.064(5) 0.129(4) 0.145 isotropic displacement parameters for 2. (U(eq.) = C324 0.373(4) 0.956(4) 0.142(3) 0.112 (U 1 ■ U 2 ■ U 3)1-'3, where U 1, U 2, U 3 are the eigenvalues C325 0.295(4) 0.908(4) 0.126(3) 0.109 of the U(ij) matrix. E.s.d.'s in parentheses). C326 0.224(4) 0.923(4) 0.191(3) 0.104 C331 0.044(3) 1.135(3) 0.205(2) 0.068 Atom x a y/b z/c U(eq. C332 -0.004(3) 1.120(3) 0.141(2) 0.078 C 333 -0.068(4) 1.196(4) 0.106(3) 0.114 A ul 0 .0 22 10 (8) 0.73650(9) 0.28863(8) 0.043 C 334 -0.005(4) 1.273(4) 0.083(4) 0.134 Au2 -0.16285(8) 0.75131(9) 0.27675(8) 0.042 C335 0.034(4) 1.300(4) 0.140(3) 0.121 Au3 0.00806(8) 0.92282(9) 0.28321(8) 0.044 C 336 0.092(3) 1.215(3) 0.172(2) 0.085 Au4 -0.17795(8) 0.93017(9) 0.29693(8) 0.044 C411 -0.390(3) 0.989(3) 0.329(2) 0.076 PI 0.1352(5) 0.6352(6) 0.2753(5) 0.046 C412 -0.471(5) 1.047(5) 0.338(4) 0.139 P2 -0.2551(6) 0.6595(6) 0.2423(6) 0.047 C413 -0.559(6) 0.990(6) 0.379(5) 0.189 P3 0 . 1000(6) 1.0356(6) 0.2499(6) 0.049 C414 -0.478(6) 0.878(7) 0.428(6) 0.221 P4 -0.2894(6) 1.0388(6) 0.2863(6) 0.053 C415 -0.494(6) 0.872(6) 0.354(5) 0.175 C l -0.079(2) 0.821(2) 0.326(2) 0.035 C416 -0.419(5) 0.918(5) 0.306(4) 0.153 C2 -0.082(2) 0.793(2) 0.401(2) 0.054 C421 -0.273(3) 1.132(3) 0.326(3) 0.090 cm 0.113(2) 0.526(2) 0.323(2) 0.048 C422 -0.259(5) 1.097(5) 0.401(4) 0.154 C 112 0.100(3) 0.526(3) 0.405(2) 0.072 C423 -0.285(8) 1.244(8) 0.424(6) 0.279 C 113 0.080(3) 0.427(3) 0.446(2) 0.072 C424 -0.163(5) 1.226(5) 0.383(4) 0.145 C 114 0.000(4) 0.394(4) 0.417(3) 0.107 C425 -0.206(6) 1.283(6) 0.323(5) 0.181 C 115 0.016(3) 0.393(3) 0.342(3) 0.097 C426 -0.188(5) 1.176(5) 0.297(4) 0.159 C 116 0.035(3) 0.491(3) 0.296(2) 0.078 C431 -0.308(3) 1.091(4) 0.195(3) 0.096 C 121 0.156(3) 0.625(3) 0.186(2) 0.068 C432 -0.386(5) 1.154(5) 0.177(4) 0.159 C 122 0.224(3) 0.540(3) 0.173(3) 0.100 C433 -0.380(6) 1.191(6) 0.099(5) 0.180 C 123 0.219(5) 0.541(5) 0.093(4) 0.146 C434 -0.375(6) 1.128(6) 0.059(5) 0.183 C 124 0.251(4) 0.626(4) 0.047(3) 0.124 C435 -0.288(5) 1.080(5) 0.063(4) 0.145 C 125 0.185(4) 0.700(4) 0.060(3) 0.123 C436 -0.301(5) 1.034(5) 0.147(4) 0.154 C 126 0.187(3) 0.711(4) 0.142(3) 0.103 76 O. Steigeimann et al. • Tetraaurio(I) Complexes

tions between neighbouring gold atoms, which are important for the stabilization of the system. Ne­ glecting the Au - Au bonding, the electron-defi­ cient nature of the hypercoordinated pentagonal- pyramidal framework with eight valence electrons for five covalent bonds can be illustrated by a sim­ plified molecular orbital diagram under idealized C4v symmetry. Symmetry allowed linear combina­ tions of the three donor electron pairs of the (for­ mal) methylcarbide trianion H 3C~C13~ and the a Fig. 3. Molecular structure of the acceptor orbitals (sp hybrids) of the four LAu* [H3C -C (A uP{C 6H m}3]+ cation of 2 (SCHAKAL, only units lead to three bonding states, which are filled the a-carbon atoms of the cyclohexyl groups are shown). - Selected bond distances [A] and angles [°]: A u l-C l by the six electrons available to give a diamagnetic 2.17(3). Au2-Cl 2.14(3), A u3-Cl 2.14(3), Au4-C 1 ground state. Therefore the bond order for each of 2.19(3), A u l- P l 2.30(1), A u 2 -P 2 2.31(1), A u 3 -P 3 the A u -C bonds is 3/4. 2.28(1), Au4-P4 2.30(1), Aul-Au2 2.849(2), Au 1 - Au3 2.865(2), Au4-Au2 2.883(2), Au4-Au3 The synthesis of the novel compounds shows 2.846(2), C 1- C 2 1.44(5), Au 1 - C 1 -A u 2 83(1), the way to the preparation of other polyaurio(I) Au 1 - C 1 - Au 3 83(1), A u 4 -C 1 - Au2 83(1), alkane species starting from materials like A u 4 -C 1 - Au 3 82( 1), A u l - C l - C 2 106(1), A u 2 -C 1 —C2 114(1), A u 3 - C l- C 2 116(1), R 2C[B(OMe)2]2. Preliminary results have indicat­ A u 4 -C 1 —C2 109(1), C l - A u l - P l 166.8(8), ed, however, that the auration sometimes is ac­ C 1 - A u 2 -P 2 169.8(8), C 1 - A u 3 - P 3 173.1(9), companied by dealkylation of the boryl ester, C 1 - A u 4 -P 4 169.9(9). which parallels the dealkylation of alkylamines observed in analogous auration reactions. Further work will be necessary to mark scope and limita­ tions of the hyperauration process. Conclusions The present study has shown that partially di- methoxyboryl substituted alkanes can be used as starting materials for the syntheses of poly- Experimental Part aurio(I)alkanes in much the same way like tetra- All experiments were carried out in an atmos­ kis(dimethoxyboryl)methane for the synthesis of phere of dry and purified nitrogen. Solvents and aurated methanes [4c, e-h]. The reaction does not glassware were dried and saturated/filled with ni­ come to a halt at the triaurated [H 3C-C(A uPR3)3] trogen. - NMR: [D2]dichloromethane as solvent, stage, but proceeds to novel penta-coordinated tetramethylsilane and phosphoric acid as reference cationic species [H 3C-C(AuPR3)4]+. This result compounds, measurement temperature 25 °C, Jeol JNM GX 270 and GX 400 spectrometers. - MS: again demonstrates the tendency of polyaurio-car- Varian MAT 311 (FD). - l,l,l-Tris(dimethoxy- bon aggregates to accept further LAu+ units. In boryl)ethane was prepared as described [ 11]. this context it is quite remarkable that for carbon- Ph 3PAuCl, (C6H n)3PAuCl and centered clusters precursors like C(AuL )4 or C 6H 4(CH 2CH 2PPh 2A uCl)2 were synthesized fol­ H 3C -C (A u L )3 are transient species for smaller li­ lowing literature procedures [12, 13, 4e]. All other gands L, whereas in the case of the ammonium and reagents were obtained commercially and used phosphonium analogues [N(AuL)5]2+ [5 d] and without further purification. [RP(AuL)4]2+ [6 b] the auration can be carried out in well defined steps [16]. 1,1,1,1-Tetrakis( triphenylphosphineaurio (I) )- According to X-ray analyses the monocations ethanium( + ) tetrafluoroborate (1) [H C-C(AuPR3)4]+ feature a square-pyramidal 3 (Triphenylphosphine)gold(I) chloride (1.00 g, geometry with an interstitial carbon, four gold at­ 2.0 mmol) and CsF (3.42 g, 22.6 mmol) in HMPT oms at the base and the methyl group at the apex. (30 ml) were treated with a solution of The short Au -Au contacts of ca. 2.8 Ä along the H 3C -C [B (O M e)2]3 (0.17 g, 0.70 mmol) in the same edges of a distorted square reflect bonding interac­ solvent (5 ml) for 24 h at 25 °C under nitrogen. O. Steigeimann et al. • Tetraaurio(I) Complexes 77

The yellow solution was filtered and the product Crystal structure determination of compound 1, precipitated with pentane. Repeated extraction [H3C~ C(AuPPh3)4]BF4 with C H 2C12 and reprecipitation with pentane/ Enraf-Nonius CAD4 diffractometer, M o~Ka benzene afforded yellow crystals of 1: yield 0.41 g radiation, X - 0.71069 Ä, graphite monochroma­ (42%); m.p. 154 °C (decomp.). - 'H N M R tor, T = -27 °C. jg (CD,Cl-,): S = 3.55 (quin, V HP = 4.9 Hz, 3 H, H 3C), Crystal data: C 74H 63A u4BF4P4, Mr = 1950.89, 7.12 (m, 24H, m-QHj), 7.31-7.36 (m, 36H, o/p- triclinic, space group PI, a = 15.167(2), b = QHs). - {'H}31P NMR (CD,Cl,): Ö = 32.1 (s). - 16.669(3), c = 19.119(3)Ä, a = 112.62(2), ß = {'H}13C NMR (CD,Cl,): Ö = 28.2 (s, C C H 3), 131.5 96.46(1), y = 90.61(1)°, V = 4425.8Ä3, Z = 2, (d, lJ cp = 51.8 Hz, C-l), 134.4 (d(cent.), 2/ CP - Dcaicd. = 1-464 gem'3, //(M o-K J = 66.99 cm '1, N = 13.0 Hz, C-2), 129.3 (d(cent.), V CP ~ N = F(000) = 1848, 13800 reflections, 13800 unique, 11.4 Hz, C-3), 131.5 (s, C-4). - MS (FD , C H 2C12): and 6234 “observed” with F 0 > 4cr(F0), data cor­ m /z(% ) = 1864.7(17), M +(cation). rected for Lorentz polarization and adsorption ef­ Analysis for C74H63Au4BF4P4 (1950.89) fects (empirically, T = 0.73-1.00). The structure Calcd C 45.56 H 3.25%, was solved by direct methods (SHELXS 86 [16]), Found C 44.93 H 3.40%. completed by difference Fourier syntheses, and re­ fined by full-matrix, least-squares techniques (SHELX 76 [17]). Au, P were refined anisotropi- 1,1,1,1-Tetrakis( tricyclohexylphospliineaurio( I))- cally as a split model (s.o. f. 0.6: 0.4), C 1, C2 iso- ethanium( + ) tetrafluoroborate (2) tropically, phenyl-C, B, F, H were neglected. Procedure as described for compound 1, tricyclo- hexylphosphine gold(I) chloride (0.51 g, 1.0 mmol), Crystal structure determination of compound 2, CsF (2.02 g, 13.4 mmol), H 3C-C[B(OMe)J3 (0.09 g, [ H3C — C (A uP { C6H 1j) 3) 4]BF4 0.40 mmol): yield 0.18 g (36%); m.p. 162 °C (de­ Enraf-Nonius CAD4 diffractometer, Mo —Ka comp.). - 'H NMR (CD,C1,): ö = 3.22 (quin, V HP radiation, A = 0.71069 A, graphite monochroma­ = 4.3 Hz, 3H, H 3C), 1.15-2.00 (m, 132H, C6H n ). tor, T = -40 °C. - {'H}31P NMR (CD,Cl,): Ö = 49.5 (s). - MS Crystal Data: C 74H 135A u4BF4P4, Mr = 2023.45, (FD, CH,C1,): m /z (% ) =" 1936.1 (100), M + (cat­ triclinic, space group Pi, a = 15.334(6), b = ion). 15.229(6), c = 19.783(6)Ä, a = 77.36(3), ß = Analysis for C74Hn5Au4BF4P4 (2023.45) 86.56(3), y = 86.00(2)°, V = 4492.1 A 3, Z = 2, ' Calcd C 43.93 H 6.72%, Dcaicd. = 1469 gem“3, /z(M o-K J = 66.02, F(000) = Found C 43.07 H 6.59%. 1992, 15820 reflections, 15820 unique, and 9691 “observed” with F 0 > 4

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