SYNTHESIS AND STRUCTURE OF BIS(THIOMETHYL)MAGNESIUM COMPOUNDS [MG(CH2SR)(2)(THF)(3)] (R = ME, PH) - THE FIRST DIMETHYLMAGNESIUM COMPOUNDS FUNCTIONALIZED BY A LEWIS-BASIC HETEROATOM

Hg(CH2SR)(2), (R = Me (1), R = Ph (2)), prepared by reaction of HgCl2 with [Li-2(CH2SR)(2)(tmeda)(2)], reacts with magnesium activated by me rcury in boiling THF to give [Mg(CH2SR)(2)(thf)(3)] (R = Me (3), R = P h (4)). 3 readily splitts off THF in vacuo to give the solvate free co mplex [Mg(CH2SMe)(2)] (3'). The complexes 3' and 4 are fully character ized by microanalysis and NMR spectroscopy (H-1, C-13). The X-ray stru cture analyses of 3 and 4 reveal mononuclear compounds with two symmet ry independent molecules in the unit cell of 3. In both complexes the coordination of Mg is trigonal-bipyramidal. The two apical positions a re occupied by THF and the three equatorial positions by one THF and t he two thiomethyl ligands. The C-Mg-C angles are slightly greater (123 .9(1)-131.0(2)degrees) than the ideal angle for equatorial atoms in a trigonal-bipyramidal coordination. In neither case, the sulfur atoms a re involved in the coordination of Mg. (C) 1998 Elsevier Science Ltd. All rights reserved.