full title:The chemistry of the hydrazido(1-)-ligand. Preparations and crystal structures of [Mo(NHNHCO2Me)(NNCO2Me)(S2CNMe 2)2], [Mo(NHNMePh)(NNMePh)(S2CNMe2)2]BPh4, and [ReCl2(NHNHCOPh)(NNHCOPh)(PPh3)2]. Mechanism of formation of substituted hydrazines from [Mo(NNRPh)2(S2CNMe2)2] (R = Me or Ph) The preparation of three complexes containing a hydrazido(1-)-ligand is described, together with a kinetic study of the intermediacy of such a species in the hydrazine-forming reaction of acid with [Mo(NNRPh)2(S2CNR′2)2] (R = R′ = Me; R = Ph, R′ = Et). Addition of 1 equivalent of HCl to [Mo(NNMePh)2(S2CNMe2)2] gives [Mo(NHNMePh)(NNMePh)(S2CNMe2)2]+ isolated as its BPh4- salt [crystal data: space group P21/n, a = 16.102(3), b = 15.669(5), c = 18.752(2) Å, α = 90.00, β = 112.23(1), γ = 90.00°, Z = 4; 3 060 independent reflections gave an R value of 0.051]. Crystal data for [Mo(NHNHCO2Me)(N2CO2Me)(S2CNMe 2)2], space group C2/c, a = 19.963(1), b = 18.855(1), c = 13.127(1) Å, α = γ = 90.0, β = 114.41(1)°, Z = 8; 1 585 independent reflections gave R 0.066. Both complexes show distorted pentagonal-bipyramidal geometries with an NN′-bonded hydrazido(1-)-ligand in the pseudo-pentagonal plane. Reaction of [ReCl2(N2COPh)(PPh3)2] with benzoylhydrazine gives [ReCl2(NHNHCOPh)(NNHCOPh)(PPh3)2] [crystal data: space group P1, a = 12.276(2), b = 14.147(2), c = 15.284(2) Å, α = 86.33(1), β = 72.04(1), γ = 83.10(1)°, Z = 2; 4 995 independent reflections gave R 0.042]. Initial protonation of [Mo(NNRPh)2(S2CNR′2)2] by HX (X = Cl or Br) gives [Mo(NHNRPh)(NNRPh)(S2CNR′2)2] +. Then, depending on R, ring closure occurs to give [Mo(NHNRPh)(NNRPh)(S2CNR′2)2]+ which competes with further protonation to give [Mo(NHNHRPh)(NNRPh)(S2CNR′2)2] 2+. Solvent attack on the latter, followed by halide substitution, leads to further protonation of the hydrazide ligand leading to loss of hydrazinium salt and formation of [MoX2(NNRPh)(S2CNR′2)2]. The complex [Mo(NHNRPh)(NNRPh)(S2CNR′2)2]+ undergoes ring opening at too slow a rate for it to be an intermediate en route to hydrazine formation in excess of acid. The kinetics of the reactions of [Mo(NHNRPh)(NNRPh)(S2CNR′2)2]+ with a variety of bases suggests the formation of the transient NN′-bonded hydrazido(2-)-complex [Mo(NNRPh)(NNRPh)(S2CNR′2)2] (R′ = R = Me) prior to regeneration of the bis[hydrazido(2-)]-complex.
|Original language||English (US)|
|Number of pages||12|
|Journal||Journal of the Chemical Society, Dalton Transactions|
|State||Published - Jan 1 1987|
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