90.71(3)", Z = 16, R = 0.052) contain tetrameric units of approximate S4 symmetry, in which the molecules are associated by means of four complementary N-H.. . N hydrogen bonds. [CH3Hg(7-azaindole)]N03 (P1 , a = 7.818(3), b = 7.884(3), c = 9.135(4) A, a = 97.89(3), P = 109.13(3), y = 103.28(3)", Z = 2, R = 0.039) contains well-separated nitrate ions and complex cations in which the methylmercury group is linearly bonded to the pyridine nitrogen atom, whereas the five-membered rin remains protonated. In the neutral [CH3Hg(azaindolate)] complex (PI, a = 10.926(10), b = 11.333(8), 8:c = 11.647(10) , a = 92.13(8), P = 104.83(9), y = 11 1.86(7)", Z = 6, R = 0.048), methylmercury groups have substituted the N-H proton in the five-membered ring for the three symmetry-independent molecules. Intermolecular secondary Hg . . . N bonds are found with pyridine nitrogens.Key words: azaindole, methylmercury, crystal structure. Chem. 68, 193 (1990). Introduction Purines and related rigid N-donor ligands have attracted our attention as potential binucleating agents for stabilizing pairs of bonded metal atoms via extended aromatic systems. 7 -~z a i n d o l e~ (Scheme 1) can be regarded as a simplified purine, retaining only a pair of nitrogen atoms properly arranged for bridging. We are currently examining its reactions with various dimetal units like M O~~+ , ~h~~+ , R U~~+ , ~e~~+ , etc. In a previous paper (I), we reported the structure of a dinuclear molybdenum system in which half of the carboxylates in M~~( a c e t a t e )~ had been replaced by bridging azaindole anions. We were able to interpret the X-ray data in terms of azaindole units disordered over two orientations, the positions of the fiveand six-membered rings being interchanged. Disorder probably resulted from the very similar van der Waals envelopes in these two orientations. The same situation has been-noted for complexes of Co, Ni, and Cu (2, 3), so that disorder in complexes of the azaindole anion is likely to be the rule rather than the exce~tion. PASCAL DUFOUR, YVES DARTIGUENAVE, MICHBLE DARTIGUENAVE, NATHALIE DUFOUR, ANNE-MARIE LEBUIS, FRANCINEThe preseA study was undertaken to help solve some of the problems encountered with our dinuclear systems. The structure determination of azaindole was intended to provide an accurate

The reactions of organolithium compounds of the type (R3Si)2CHLi (R3 = Me3 or Me2Ph) with the gold(I) complex Ph3PAuCl afford the monoaurated bis(silyl)methanes (R3Si)2‐ CHAuPPh3 (1a, b) in high yield. These compounds are converted into complex salts with hypercoordinate methanium cations {(R3Si)2C[Au(PPh3)]3}+BF−4 (3a, b) by treatment with {[(Ph3P)Au]3O}+ BF−4. In the reaction mixtures small amounts of the neutral dinuclear intermediates {(R3Si)2C[Au(PPh3)]2} (2a, b) have been detected and characterized by their spectroscopic data. Compounds 1a, b and 3a, b have been studied by single crystal X‐ray diffraction analyses. While the mononuclear molecules 1a, b have conventional structures with parameters representing classical types of bonding, the novel trinuclear complexes 3a, b feature cations with a pentacoordinate carbon atom in a distorted trigonal‐bipyramidal environment of two silicon atoms and one gold atom in equatorial positions and the remaining two gold atoms at the axial vertices of the polyhedra. The main axis of the bipyramid is strongly bent at the central carbon atoms. This distortion leads to short axial/equatorial Au…Au distances indicating peripheral metal‐metal bonding.

. Can. J. Chem. 70, 2914Chem. 70, (1992. Complexes of the types [CH,Hg(aza)], [CH,Hg(Haza)]X, and [(CH,Hg)z(aza)]X are obtained by reacting CH,HgOH and/or CH,HgX (X = NO,, C10,) with 7-azaindole (Haza). The weakly acidic NI-H proton on the pyrrole ring is displaced by the hydroxide, whereas the perchlorate and nitrate salts lead to CH3Hg+ coordination to the N7 lone pair on the pyridine ring. Detailed analysis of the infrared spectra of the complexes and their N-deuterated derivatives provides diagnostic regions for eventual prediction of the coordination mode in other systems. All compounds are characterized by means of 'H, "C, and ""Hg NMR spectra in DMSO solution and solid-state CP-MAS "C spectra. Comparison of the solution and solid-state "C spectra show that the species present in the solids remain undissociated in DMSO. Each type of complex can be identified from a characteristic pattern of large displacements of the ligand I3C signals. The ' H spectra are less informative because substitution of the Nl-H proton by CH,Hg' induces only minor shifts. Metal solvation appears to have a major influence on the "C and ' "~g chemical shifts of the CH,Hg' groups. dans Ics solides demeurent intactes dans le DMSO. Chaque type de complexe peut &tre identifie d'apres un ensemble carr~ctCristique de deplacements importants des signaux "C du ligand. Les spectres 'H sont moins revklateurs, parce que la substitution du proton Nl-H par CH,Hg' ne produit que de faibles dkplacements. La solvatation autour du ~nktal selnble exerccr une grande influence sur les deplacements chirniques "C et Hg des groupes CH,HgT.

solution with Rh2(CO)4Cl2 in dichloromethane to give the known9 CoRh(p-dppm)2(p-CO)(CO)2(p-Cl)]Cl (9) in 43% yield. Further such studies are in progress.Acknowledgment. The financial support of the Natural Sciences and Engineering Research Council of Canada (to D.G.H., A.N.H., and R.J.P.) is gratefully acknowledged.Supplementary Material Available: Tables of atomic coordinates, isotropic and anisotropic thermal parameters, and bond distances and angles for 1 and 0RTEP diagrams of 1 (5 pages); a listing of structure factors for 1 (20 pages). Ordering information is given on any current masthead page. NotesImlne-Transfer Reactions from Zirconium to Phosphorus and Boron.

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