Distortions in six-co-ordinate complexes of molybdenum(II) and tungsten(II). Crystal structures of mer-[Mo(SC6H2Pri3-2,4,6)2(CO)3(PMePh2)], cis,cis,cis-[W(SC6H2Me3-2,4,6)2(CO)2-(PMe2Ph)2] and [W(SeC6H3Pri2-2,6)2(CO)2(PMe2Ph)2]
Abstract
The red, diamagnetic complexes mer-[Mo(SC6H2 Pri3-2,4,6)2(CO)3(PMePh2)]1 and [Mo(SC6H2Pri3-2,4,6)2(CO)2(PMePh2)2]2 have been prepared by reaction of [MoH(SC6H2Pri3-2,4,6)3(PMePh2)] 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)Å; large S–Mo–S angle of 116.0°]. Reaction of CO with [WH(SC6H2Me3-2,4,6)3(PMe2Ph)2] in toluene gives green, distorted octahedral cis,cis,cis-[W(SC6H2Me3-2,4,6)2(CO)2(PMe2Ph)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)Å]. Reaction with [WH(SeC6H3Pri2-2,6)3(PMe2Ph)2] gives burgundy, trigonal prismatic [W(SeC6H3Pri2-2,6)2(CO)2(PMe2Ph)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)Å]. 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.