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Radiation yields of N 2 H 4 , NH 3 and the catalytic efficiency for [Mo(N 2 ) 2 (trifos)(PPh 3 )] and [Mo(N 2 ) 2 (dppe) 2 ] in slightly acidified (concentration of H 2 SO 4 related to the number of N 2 fixing and reducing cycles) and non-acidified THF+C 6 H 12 solutions were determined. The studies proved that the Mo-H groups play the dominating role in the process of molecular N 2 reduction.

A radiation-catalytic experiment of the fixation and reduction of molecular nitrogen has been carried out. The [WH 4 (dtpe) 2 ] complex was applied to fix molecular nitrogen in a γ-radiation field. Plots of the dependence of either the number of molecules of ammonia or hydrazine vs dose are presented. A mechanism for the radiation-catalytic fixation and reduction of molecular nitrogen using the [WH 4 (dtpe) 2 ] complex is suggested. The unusually high radiation yields of ammonia and hydrazine are explained as due to a cyclic process.

The molybdenum hydrazido complex [Mo(NHH2)(HSO4)(dppe)2]HSO4 was used in the process of fixation and reduction of molecular nitrogen in γ-radiation field. This process has been found as a catalytic one. Results of this work generally confirm conclusions of the previous works and some new aspects of the mechanism of this process are discussed.

The two molybdenum(IV) hydride complexes [MoH4(dppe)2][dppe = (C6H5)2 PCH2CH2P(C6H52] and [MoH4(dtpe)2] [dtpe =(o-CH3C6H4)2PCH2CH2P(o-CH3C6H4)2] were applied in a process of radiation-catalytic reduction of molecular nitrogen. The yields of ammonia and hydrazine were determined for different concentrations of these complexes in cyclohexane solutions. The mechanism of the reduction of molecular nitrogen by γ-radiation is suggested. It has also been discovered that the [MoH4(LL)2] complexes are useful in the process of radiation-catalytic fixation and reduction of nitrogen.

On the basis of experimental data the energy levels of the central-atom orbitals in the complex [Mo(N2)2(dppe)2] [dppe = 1,2-bis(diphenylphosphine)ethane] were calculated. Using the diagram thus obtained the eletronic configuration of the irradiation-generated ion, [Mo(N2)2(dppe)2]−, was determined to be as follows: (b2g)2 (eg)4 (b1g)1 or (b2g)2 (eg)4 (eu). The yields from the decomposition of [Mo(N2)2(dppe)2] in the solid phase in a hydrogen atmosphere were determined on the basis of the decrease in band intensities at 306 and 377 nm: G(− MoN2)306nm = 0.01, and G(− MoP)377nm = 0.1 (molecules per 100 eV). In toluene solution it was found that G(− MoN2) > G(− MoP). The yields observed were in accordance with the calculated levels. Using a mass spectrometer the volatile products of [Mo(N2)2(dppe)2] radiolysis in H2 and O2 atmospheres were identified as H3N, H4N2, NO and N2O. In the light of the results mentioned above (as well as the IR results) a mechanism for the radiolysis of [Mo(N2)2(dppe)2] in the solid phase was proposed.

The [MoOC1(dppe)2]Cl complex [dppe=(C6H6)2P(CH2)2 P(C6H5)2] was successfully examined in a process of reduction of molecular nitrogen in γ-radiation field. Yields of ammonia produced in this process were measured as a function of the Mo(IV) complex concentration and dose.