DOMINATION OF ELECTRONIC FACTORS IN THE SELECTIVE METAL TO CARBON BOND FORMATION IN BINUCLEAR MANGANESE MOLYBDENUM COMPLEXES WITH S(2)CPR(3) BRIDGES

Reactions of the heterodinuclear anion [MnMo-(CO)(6)(mu-S2CPPr3i)](-) (2) with PhSeI and Ph(2)PCl produce the hexacarbonyls [MnMo(CO)(6)(mu- SePh)(mu-S2CPPr3i)] (4; monoclinic, space group P2(1)/n, a = 10.334(2) Angstrom b = 12.901(3) Angstrom, c = 20.367(3) Angstrom, beta = 96.15 (1)degrees, V = 2700(1) Angstrom(3), Z = 4, R = 0.028, R(w) = 0.027 fo r 2886 reflections) and [MnMo(CO)(6)(mu-PPh(2))(mu-S2CPPr3i)] (5), whi ch does not have an Mn-Mo bond and in which the central carbon of S2CP Pr3i is bonded to Mo. On standing in solution, hexacarbonyl 5 loses CO to afford the pentacarbonyl [MnMo(CO)(5)(mu-PPh(2))(mu-S2CPPr3i)] (6; monoclinic, space group P2(1)/n, a = 10.413(2) Angstrom, b = 13.734(4 ) Angstrom, c = 21.761(8) Angstrom, beta = 101.01(2)degrees, V = 3055( 2) Angstrom(3), Z = 4, R = 0.045, R(w) = 0.045 for 2464 reflections), which contains a direct Mn-Mo bond and in which the central carbon of S2CPPr3i is bonded to Mn. An analysis of he structures of 4-6 shows th at the rearrangement of S-2-CPR(3) is induced by electronic effects. T hus, a change in the electron distribution within the heterobimetallic complex (as it occurs in the reaction from 5 to 6) forces the central carbon of S(2)CPR(3) to migrate to the metal with the lowest oxidatio n number.