SYNTHESIS AND COMPARISON OF SPECTROSCOPIC PARAMETERS AND MOLECULAR-STRUCTURE OF AN-O)MAGNESIUM-BIS[BIS(TRIMETHYLSILYL)PHOSPHANIDE] AND FURAN-O)MAGNESIUM-BIS[BIS(TRIMETHYLSILYL)ARSANIDE]

The reaction of Magnesium n/sec-dibutanide with bis(trimethylsilyl)pho sphane, respectively -arsane in THF yields derivatives of the type [(M e(3)Si)(2)E]Mg-2.2THF (E = P, As). Magnesium-bis[bis(trimethylsilyl)ph osphanide].2THF crystallizes in the monoclinic space group C2/c with a = 1861.7(3) pm, b = 976.0(3) pm, c = 1921.2(3) pm, beta = 109.67(1)de grees and Z = 4. The homologous arsanide crystallizes in the triclinic space group P (1) over bar with a = 980.7(2) pm, b = 1266.1(2) pm, c = 1437.6(2) pm, alpha = 78.29(1)degrees, beta = 88.02(2)degrees, gamma = 70.28(1)degrees and Z = 2. In both compounds the magnesium atoms ar e coordinated distorted tetrahedrally, the pnictogen atoms display pyr amidal surroundings.