REACTION OF TRIMETHYLALUMINUM AND TRIMETHYLGALLIUM WITH BIFUNCTIONAL AMINES - SYNTHESES AND MOLECULAR-STRUCTURES OF [ME2AL-N(CH2CH2)2-C-(OCH2)2]2 AND [ME2GA-N(SI(H)ME2)2]2

The crystalline products [Me2Al-N(CH2CH2)2-C-(OCH2)2]2 (I) and [Me2Ga-N(Si(H)Me2)2]2 (II) were prepared from reactions of trimethylaluminum and trimethylgallium with 1,4-dioxa-8-azaspiro[4.5]decane and 1,1,3,3-tetramethyldisilazane, respectively, in toluene. The organoaluminum dimer crystallizes in the monoclinic space group P2(1)/c with unit cell parameters a = 8.970(2)angstrom, b = 9.683(2)angstrom, c = 12.833(3)angstrom, beta = 103.18(2)degrees, V = 1085.3(3)angstrom3, and D(calcd) = 1.22 g cm-3 for Z = 2. Least-squares refinement based on 935 observed reflections I > 3sigma(I) in the range 3.5-degrees < 2theta < 45.0-degrees led to a final R factor of 0.033 (R(w) = 0.041). The dimeric organosilazagallium crystallizes in the triclinic space group P1BAR with unit cell parameters a = 7.636(2)angstrom, b = 9.168(2)angstrom, c = 9.466(3)angstrom, alpha = 72.81(2)degrees, beta = 87.94(2)degrees, gamma = 69.90(2)degrees, V = 593.0(3)angstrom3, and D(calcd) = 1.30 g cm-3 for Z = 1. Least-squares refinement based on 1661 observed reflections I > 3sigma(I) in the range 3.5-degrees < 2theta < 48.0-degrees led to a final R factor of 0.055 (R(w) = 0.070). Both compounds I and II reside about a crystallographic center of symmetry and contain a planar M2N2 (M = Al for I, Ga for II) four-membered ring with I having an Al ... Al contact of 2.801 angstrom.