Pdyhedron Vol. 8, No. 15, pp. 19094912, 1989 Printed in Great Britain 0277-5387/89 S3.00+.00 0 1989 Maxwell Rrgamon Macmillan plc zyxwvutsr SYNTHESIS OF 1,3_DIPHENYLTRIAZENIDE COMPLEXES OF ALUMINIUM, GALLIUM AND INDIUM: CRYSTAL STRUCTURE OF TRIS(l,3-DIPHENYLTRIAZENIDO)ALUMINIUM(III) JOHN T. LEMAN and ANDREW R. BARRON* Chemical Laboratories, Harvard University, Cambridge, MA 02138, U.S.A. and JOSEPH W. ZILLER Department of Chemistry, University of California, Irvine, CA 92717, U.S.A. and ROBERT M. KREN Department of Chemistry, University of Michigan-Flint, Flint, MI 48502, U.S.A. zyxwvutsrqponml (Received 26 January 1989 ; accepted 2 1 February 1989) Abstract-The reaction of AlMe with 1,3_diphenyltriazene [Hdpt] in toluene gives Al(dpt)3, even when AlMe, is in large excess. The monomeric structure has been established by X- ray diffraction. Crystals of Al(dpt)3 are monoclinic, space group C2/c with a = 20.587(3), b = 16.005(3), c = 13.236(3) 8, and b = 119.172(12)“, Z = 4, R = 0.067 and R, = 0.083. The aluminium(II1) is coordinated by three chelating triazenido ligands to give a trigonally distorted octahedral geometry. The gallium and indium analogues are also reported. The triazenide anion, RN=N-NR-, might be expected to display a variety of coordination modes. Transition metal complexes containing mono- dentate (l), chelate (2) and bridging (3) triazenide ligands have been reported,’ suggesting a formal analogy to the carboxylate anion, G==C(R)-G. Despite this analogy and the wide range of Group III carboxylates reported in the literature,2 the only examples of Group III triazenides are Tl(dpt), (Hdpt = 1,3_diphenyltriazene) and TlO?pt) 3 (Hppt = l-phenyl-3-(2’-pyridyI)triazene), which were characterized as tris-chelate complexes by IR spectroscopy,3 and the dimeric [Tl(dpt)12 whose structure was determined by X-ray crys- tallography. 4 * Author to whom correspondence should be addressed. We now report the synthesis and characterization of the tris( 1,3-diphenyltriazenido)aluminium(III), gallium(II1) and indium(II1) complexes. RESULTS AND DISCUSSION The complex Al(dpt)3 (Hdpt = 1,3-diphenyl- triazene) was first obtained in low yield from the reaction of AlC13 with Li(dpt). An improved pro- cedure, however, is the direct reaction of Hdpt with AlMe, in toluene. The compound Al(dpt), has been fully char- acterized by elemental analysis and spectral data. The ‘H NMR spectrum, in CDC13, shows an A2B2C pattern for the monosubstituted phenyl groups, indicating that the triazenides are either fluxional on an NMR time scale, or in a symmetrical environ- ment. The 27A1 NMR spectrum consists of a broad peak whose shift (6 = 25 ppm) is indicative of a six-coordinate aluminium centre,’ but is extremely broad (wlj2 = 1160 Hz), possibly exacerbated by coupling to the quadrupolar 14N nuclei. The IR 1909