Crystal and Molecular Structure of the N-Methyldiethanolaminogallane Dimer, [CH3N(CH2CH2O)2GaH]2
Crystals of the N-methyldiethanolaminogallane dimer are orthorhombic, a = 19.112(4), b = 9.947(2), c = 7.709(2) Å, Z = 4, space group P212121. The structure was determined by Patterson and Fourier synthesis and was refined by full-matrix least-squares procedures to a final R of 0.056 for 1477 observed reflections. The structure provides the first1 known crystallographic example of pentacoordinate gallium, the dimerization of MeN(CH2CH2O)2GaH occurring via the formation of a four-membered Ga2O2 ring. The coordination about the gallium is distorted trigonal bipyramidal with an angle of 151.2(4)° between the axial substituents. The mean bond distances are: Ga—N, 2.192(5), and Ga—O, 2.018(2) for axial ligands; Ga—O, 1.847(2), 1.960(8), and Ga—H, 1.41(4) for equatorial ligands; O—C, 1.419(14), C—N, 1.470(7), C—C, 1.520(12), and C—H, 1.00(13) Å. The molecule has C2 symmetry to within experimental error. There are possible [Formula: see text] hydrogen bonds ([Formula: see text] 3.13(1)–3.44(1) Å) in the structure.