Two new alkylimido-methylgallanes with cage structure

The tetrameric alkylimido-methylgallanes (MeGa-NR)(4) (R = CH(CH3)(2) (corresponding to Pr-i), C(CH3)(3) (corresponding to (BU)-B-t) and Me = CH3) have been prepared by pyrolyses of the dimeric amido compounds (Me(2)Ga-N(H)R)(2) at 250-260 degrees C. The mass, NMR and vibrational spectra are discussed, they prove almost identical structures of the skeletons. The X-Ray structure determination of (MeGa-N(t)Bu)(4) shows four heterocubane molecules in the trigonal unit cell (space group <P(3)over bar cl>, a = b = 1061.7(1), c = 3191.8(5) pm) and two disordered benzene solvate molecules. The Ga-N bonds range between 198.4 to 199.9 pm, the Ga-N-Ga and N-Ga-N bond angles lie between 90.6 to 91.4 and 88.6 to 89.2 degrees, respectively. The structure was refined to an R(1)(R(2))-value of 0.049 (0.057).