Triangular Trinuclear Cluster Compounds: Molybdenum and Tungsten Complexes of the Type + with X = Cl and H

Article abstract of DOI:10.1021/ja00194a027

New synthetic methods of an essentially nonaqueous nature are reported for the preparation of compounds containing the Mo3S4⁴⁺ and W3S4⁴⁺ cluster cores surrounded by a combination of diphosphine ligands and either Cl^- or H^- ligands.The synthetic methods entail reactions of MoCl3(THF)3 or WCl4 with NaHS and dmpe (or depe) in THF to obtain the chloro species and treatment of tungsten chloro compounds with LiBH4 to obtain the hydrido compounds.The new compounds described in detail (including crystal structures for those marked^*) are as follows: CH3OH^* (1), *H2O^* (2), ^* (3), ^* (4), and (5).Compounds 1 and 2 form isomorphous crystals in space group R3c with Z=6; for 1, a = 15.310 (7) Angstroem and c = 30.640 (3) Angstroem; for 2, a = 15.269 (2) Angstroem and c = 30.620 (6) Angstroem.The two cations have almost identical dimensions, with Mo-Mo = 2.766 (4) Angstroem, W-W = 2.755 (1) Angstroem, and all other distances (e.g., M-S, M-Cl, M-P) equal within +/- 0.01 Angstroem.In each case, the dmpe ligands span positions such that one P is trans to μ₃-S and the other trans to a μ₂-S atom within the approximately octahedral coordination sphere, MS3ClP2, about each metal atom.The cations are therefore chiral.The ⁺ ion in compound 3 is very similar to the ⁺ ion in 2.Compound 3 crystallizes in space group P<*> with Z = 2, a = 15.552 (6) Angstroem, b = 17.768 (7) Angstroem, c = 10.572 (3) Angstroem, α = 106.54 (3) deg, β = 98.25 (3) deg, γ = 95.70 (3) deg.Compound 4 has a cation nearly isostructural with that in 2 except that each Cl atom is replaced by an (X-ray-invisible) H atom.The W-W distances are equal in the two cations.Compound 4 crystallizes in space group P2₁/c with Z = 4, a = 14.947 (2) Angstroem, b = 11.237 (2) Angstroem, c = 32.942 (5) Angstroem, β = 97.90 (1) deg.The two hydrido compounds, 4 and 5, react smoothly with PhCOCl to regenerate the chloro compounds.The ⁺ ion undergoes two quasirreversible one-electron reductions (-0.64 and -0.85 V vs Ag/AgCl electrode).The ⁺ and ⁺ ions showed reductions at -1.11 and -1.12 V that appear to produce unstable products.NMR studies of the cation in 2, 4, and 5 support the formulation of 4 and 5 as hydride complexes. 4 and 5 show (1)H resonances at -0.914 and -0.80 ppm, respectively, which appear as doublets of doublets with ²J_HP values of 30 and 45 Hz and satellites with ¹J_HW of ca. 30 Hz.