Title full: The cleavage of the NN bond of N,N-disubstituted hydrazines on rhenium. The preparation, reactions and x-ray crystal structures of [ReCl2(NH3)(NNCOC6H4-4-R)(PP h3)2] (R = H, OMe, NO2), [ReCl3(NNPh2)(PPh3)2], [ReCl2(N)(NNPh2)(PPH3)] and [ReCl(N)(Me2CNNCOPh)(PPh3)2]. Reaction of the N,O-chelated complexes [ReCl2(N2COC6H4-4-R) (PPh3)2] (R = H, Me, NO2) with N,N- and certain N-substituted hydrazines gave the ammine complexes [ReCl2(NH3)(NNCOC6H4-4-R)(PP h3)2][R = H (1), R = Me (2), R = NO2 (3). The mechanism is believed to involve intermolecular homolytic cleavage of the NN bond. The x-ray structure of 1 revealed a pseudo-octahedral geometry with trans-phosphines. The ammine ligand is cis to the benzoyldiazenido group and the ammine hydrogens are hydrogen-bonded to the carbonyl oxygen. Reaction of [ReOCl3(PPh3)2] with excess Ph2NNH2 · HCl in ethanol gave both [ReCl3(NNPh2)(PPh3)2] (6) and [ReCl2(N)(NNPh2)(PPh3)] (7). In the presence of base the rhenium(VII) cation [ReCl2(NNPh2)2(PPh3)+ was formed. The geometry of 7 was shown by X-ray structural determination to be a distorted square-based pyramid, with the nitride in the apical position. Attempted derivatization of 7 led to NN bond cleavage and the generation of nitrido complexes. The nitrido complex [ReCl(N)(Me2CNNCOPh)(PPh3)2] (8) was unexpectedly formed in the reaction of [ReOCl3(PPh3)2] with Me2CNNHCOPh in ethanol in the presence of HCl. The X-ray crystal structure of 8 showed a pseudo-octahedral geometry with the nitride ligand trans to the oxygen of the N,O-chelated hydrazonato(1-) ligand. The possible mechanisms of NN bond cleavage are discussed.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Inorganic Chemistry
- Materials Chemistry