Reactions of coordinated dinitrogen—XXII. Synthesis, characterization and reactions of hydrazido(2-) complexes of molybdenum. Crystal structures of two hydrazido(2-) complexes

The reactions of anhydrous HX (X = Br, Cl) with trans-Mo(N2)2(triphos) (PPh3) (1) where triphos = PhP(CH2CH2PPh2)2, yield [MoX(NNH2)(triphos)(PPh3)]X as a mixture of isomers: 1A(X) and 1B(X). In solution, PPh3 dissociates rapidly from the B isomer. Addition of PPh3 to a mixture of 1A(X) and 1B(X) enabled the separation of the isomers by fractional crystallization. Addition of PPh2Me to a mixture of 1A(X) and 1B(X) led to the isolation of 1A(X) and [MoX(NNH2)(triphos)(PPh2Me)]X [2B(X)]. Amber 1A(Cl) crystallizes with one molecule of toluene in the monoclinic space group P21 with a = 13.714(2), b = 13.924(2), c = 14.279(3) A, β = 102.44(1)°, and Z = 2. Olive-green 2B(Cl) crystallizes with two molecules of salvation; one each of pentane and toluene, in the triclinic space group P 1 with a = 12.922(2), b = 13.552(3), c = 18.067(4) A, α = 106.04(1), β = 107.65(1), γ = 97.22(1)°, and Z = 2. Loss of PPh3 from 1B(X) is proposed to be due to steric factors. Yields of ammonia and hydrazine formed from all the nitrogen hydride complexes are summarized.