Novel synthetic route to molybdenum hydrido-thiocarbamoyl and hydrosulfido-carbyne complexes by reactions of trans-Mo(N2)2(R2PC2H4PR2)2 with N,N-dimethylthioformamide

Article abstract of DOI:10.1021/om00007a043

The reactions of bis(dinitrogen)molybdenum complexes trans-Mo(N₂)₂(R₂PC₂H₄PR₂)₂ (R = Ph, Et) with N,N-dimethylthioformamide (HC(S)NMe₂) in refluxing benzene under argon give the molybdenum hydrido-thiocarbamoyl complexes MoH(η²-C(S)NMe₂)(R₂PC₂H₄PR₂)₂ (R = Ph (1a), Et (1b)). On heating at 125°C in toluene solutions, compounds 1a and 1b rearrange to form the molybdenum hydrosulfido-aminocarbyne complexes trans-Mo(SH)-(=CNMe₂)(R₂PC₂H₄PR₂)₂ (R = Ph (2a), Et (2b)). A mechanism is proposed for this thermal rearrangement which involves migration of the hydride ligand from molybdenum to the sulfur atom of the thiocarbamoyl ligand to give the 16-electron Fischer carbene intermediate Mo-(=C(SH)NMe₂)(R₂PC₂H₄PR₂)₂, followed by migration of the hydrosulfido group from the carbene carbon to molybdenum. The molecular structures of compounds 1a and 2a have been determined by single-crystal X-ray diffraction studies. Crystallographic data for 1a: monoclinic, space group C2/c, a = 19.536(4) A, b = 15.950(3) A, c = 15.793(3) A, β = 105.54(3)°, V = 4741(2) A³, Z = 4, and R = 0.037. Crystallographic data for 2a: monoclinic, space group P2₁/c, a = 19.516(4) A, b = 12.301(2) A, c = 19.899(4) A, c β = 102.46(3)°, V = 4665 (2) A³, Z = 4, and R = 0.062.