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 CS 2 on the high-valent tetrathiometalate MoS 4 2 - . The mononuclear compound (NEt 4 ) 3 [Mo(η 2 -CS 3 ) 4 ], 1, was selectively produced by reaction of (NEt 4 ) 2 [MoS 4 ] with excess of CS 2 in a mixture of CH 3 OH and NH 3 in the presence of H 2 S. Compound 1 crystallizes in the monoclinic system, space group P 2 1 / 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 η 2 -CS 3 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 [MoS 4 ] 2 - with CS 2 without H 2 S gives (NBu 4 ) 2 [Mo 2 (η 2 -CS 3 ) 4 (μ-(S 2 ) 2 ], 2, obtained as a powder which was recrystallized at 4 °C. Compound 2 crystallizes in the monoclinic system, space group P 2 1 / 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 η 2 -CS 3 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.