Synthesis and Structural Characterizations of New Mononuclear and Dinuclear Molybdenum(V) Anions Containing Trithiocarbonate Ligands

This paper describes the syntheses and structures of two new Mo(V) compounds obtained via the reductive addition
of CS2 on the high-valent tetrathiometalate MoS42-. The mononuclear compound (NEt4)3[Mo(η2-CS3)4], 1, was
selectively produced by reaction of (NEt4)2[MoS4] with excess of CS2 in a mixture of CH3OH and NH3 in the
presence of H2S. Compound 1 crystallizes in the monoclinic system, space group P21/n, a = 18.5249(5) Å, b =
11.8058(4) Å, c = 20.2942(5) Å, β = 102.951(1)°, Z = 4. In total, 11 176 reflections with I > 2σ(I) were
employed, and the structure solution was refined to R = 0.0496. Compound 1 was revealed to be a mononuclear
paramagnetic species containing only η2-CS3 ligands. The geometry at the Mo(V) center is described as a regular
dodecahedron. Compound 1 represents a unique example of a stable mononuclear Mo(V) complex containing
trithiocarbonate ligands. The reaction of [MoS4]2- with CS2 without H2S gives (NBu4)2[Mo2(η2-CS3)4(μ-(S2)2],
2, obtained as a powder which was recrystallized at 4 °C. Compound 2 crystallizes in the monoclinic system,
space group P21/n, a = 8.7930(1) Å, b = 22.3059(3) Å, c = 14.5029(2) Å, β = 98.445(1)°, Z = 4. In total, 8323
reflections with I > 2σ(I) were used, and the structure solution was refined to conventional R = 0.0425. Compound
2 is a dinuclear species containing η2-CS3 ligands, the two Mo(V) being linked through two disulfido bridging
groups. The Mo−Mo distance in 2 is 2.8128(6) Å, a value in very good agreement with those observed for
dinuclear Mo(V) species.