Disproportionation and reduction of hydrazine at a molybdenum–thiolate centre: crystal structures of [MoH(SC6H2Pri3-2,4,6)3(NH3)(PMePh2)] and [MoH(SC6H2Pri3-2,4,6)3(NH2NHPh)(PMePh2)]

Abstract

In the presence of [MoH(SC₆H₂Prⁱ₃-2,4,6)₃(PMePh₂)] in tetrahydrofuran (thf), anhydrous N₂H₄ disproportionates to N₂ and NH₃ or is reduced to NH₃ by Zn–HOC₆H₃Prⁱ₂-2,6 (69–81% conversion over 16 h). Reaction of [MoH(SC₆H₂Prⁱ₃-2,4,6)₃(PMePh₂)] with anhydrous N₂H₄ in thf–MeOH at low temperature gave the complex [MoH(SC₆H₂Prⁱ₃-2,4,6)₃(NH₃)(PMePh₂)] which was shown by a crystal-structure determination to have a trigonal girdle of thiolate ligands with essentially apical NH₃ and PMePh₂ ligands [d(Mo–N), 2.298(15); d(Mo–S) (mean), 2.339(5) Å]. A similar reaction using NH₂NHPh instead of N₂H₄ gave [MoH(SC₆H₂Prⁱ₃-2,4,6)₃(NH₂NHPh)(PMePh₂)], which has an analogous crystal structure to [MoH(SC₆H₂Prⁱ₃-2,4,6)₃(NH₃)(PMePh₂)] [d(Mo–N), 2.278(5); d(Mo–S) (mean), 2.332(2); d(N–N) 1.451(7) Å]. Spectroscopic data for these compounds are discussed in terms of their structures. The unstable adduct [MoH(SC₆H₂Prⁱ₃-2,4,6)₃(NH₂NMe₂)(PMePh₂)] has been characterised spectroscopically in solution.