STRUCTURAL AND SPECTROSCOPIC CHARACTERIZATION OF THE COMPOUNDS [AL(NME2)3]2, [GA(NME2)3]2, [(ME2N)2AL(MU-N(H)1-ADAMANTANYL)]2 AND [(ME(MU-NPH2)AL)2NPH(MU-C6H4)]

The compounds [Al(NMe2)3]2 (1), [Ga(NMe2)3]2 (2), [(Me2N)2Al{μ-N(H)1-Ad}]2 (3) and [{Me(μ-NPh2)Al}2 NPh(μ-C6H4)]·0.5PhMe (4) have been structurally and spectroscopically characterized by X-ray crystallography, 1H, 13C, 27Al, 69Ga and 71Ga NMR. A new synthesis is also provided for the previously known compound 1. The structures of 1 and 2 are the first reported structures of tris-dialkylamides of aluminium or gallium. Both possess dimeric structures in the solid with dimethylamide bridges and distorted tetrahedral geometry at the metal. The terminal -NMe2 groups display significant deviation from planarity in both compounds. The transamination reaction between 1 and 1 equiv. of 1-AdNH2 affords 3 in high yield. The compound 4 was synthesized by treatment of AlMe3 with 2 equiv. of HNPh2 in refluxing toluene. The ortho-metallated product, 4, is somewhat surprising in view of the prior synthesis of Al(NPh2)3 via a similar reaction. Crystal data at 130 K with Mo-Kα (λ = 0.71069 Å) radiation are as follows; 1, triclinic, a = 7.224(3), b = 8.545(3), c = 8.792(3) Å, α = 61.61(2), β = 85.02(3), γ = 88.76(3)°, Z = 1, space group P1, R = 0.041; 2, triclinic, a = 7.306(4), b = 8.514(4), c = 8.809(4) Å, α = 61.11(3), β = 85.13(4), γ = 89.14(4)°, space group P1, Z = 1, R = 0.035; 3, monoclinic, a = 8.420(5), b = 18.487(6), c = 10.319(5) Å, β = 108.44(4)°, space group P21/c, Z = 2, R = 0.047; 4, monoclinic, a = 16.069(6), b = 13.053(5), c = 16.424(4) Å, β = 97.57(2)°, space group P21/c, Z = 4, R = 0.066. © 1990.