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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.

The synthesis is reported of a mono-dinitrogen complex of molybdenum, Mo(N2)(triphos)(PMe2Ph)2, where triphos = PhP(CH2CH2PPh2)2, that yields significant yields of ammonia and hydrazine when treated with HCl or HBr in organic solvents. Generally, increasing the temperature increases the combined yield of ammonia and hydrazine.

The mono-N2 complex fac-Mo(N2)(triphos)(L2) (1), where triphos = PhP(CH2CH2PPh2)2 and L = PMe2Ph, reacts with HX (X = Br, Cl) to give the hydrazido(2—) complex, [Mo(NNH2)(η2-triphos)(PMe2Ph)2]X (2), in which triphos is bidentate. Complex 1 reacts with HBr (1 mol) to give an almost quantitative yield of MoHBr(triphos)(PMe2Ph) (3). With HBr (1 mol), 3 produces MoH2Br(triphos)(PMe2Ph).