DISTORTIONS IN 6-CO-ORDINATE COMPLEXES OF MOLYBDENUM(II) AND TUNGSTEN(II) - CRYSTAL-STRUCTURES OF MER-[MO(SC6H2PR3I-2,4,6)(2)(CO)(3)(PMEPH(2))], CIS,CIS,CIS-[W(SC(6)H(2)ME(3)-2,4,6)(2)(CO)(2)-(PME(2)PH)(2)] AND [W(SEC6H3PR2I-2,6)(2)(CO)(2)(PME(2)PH)(2)]

The red, diamagnetic complexes mer-[Mo(SC6H2Pr3i-2,4,6)(2)(CO)(3)(PMePh(2))] 1 and [Mo(SC6H2Pr3i- 2,4,6)(2)(CO)(2)(PMePh(2))(2)] 2 have been prepared by reaction of [MoH(SC6H2Pr3i-2,4,6)(3)(PMePh(2))] with CO in tetrahydrofuran, The crystal structure of 1 shows it to have a distorted octahedral geometry with mer-CO ligands [d(Mo-S) 2.380(1) and 2.366(1); d(Mo-C) 2.030(5). 2.026(4) and 2.066(5); d(Mo-P) 2.561(1) Angstrom; large S-Mo-S angle of 116.0 degrees]. Reaction of CO with [WH(SC(6)H(2)Me(3)-2,4,6)(3)(PMe(2)Ph)(2)] in toluene gives green, distorted octahedral cis,cis,cis-[W(SC(6)H(2)Me(3)-2,4,6)(2)(CO)(2)(PMe(2)Ph)(2)] 3 [d(W-S) 2.379(2) and 2.385(2); d(W-C) 1.967(7) and 1.991(8); d(W-P) 2.556(2) and 2.507(2) Angstrom]. Reaction with [WH(SeC6H3Pr2i-2,6)(3)(PMe(2)Ph)(2)] gives burgundy, [W(SeC6H3Pr2i-2,6)(2)(CO)(2)(PMe(2)Ph)(2)] 4 [d(W-Se) 2.506(1) and 2.583(1); d(W-C) 1.942(8) and 1.943(8); d(W-P) 2.467(2) and 2.471(2) Angstrom]. The physical properties of 1-4 and the structures of 1, 3 and 4 are discussed in terms of their distortions from regular octahedral or trigonal-prismatic geometries. A method of classifying such structures is proposed.