Reactions of molybdenum oxo-complexes with substituted hydrazines. Part 1. The preparation of molybdenum alkyl- and aryl-imido-complexes; the crystal and molecular structure of (N-benzoyl-N′-p-tolyldiazene-N′O)dichloro(dimethylphenylphosphine)(p-tolylimido)molybdenum

Abstract

The molybdenum(IV) oxo-complexes [MoOCl₂(PR″₃)₃](PR″₃= PMe₂Ph or PEt₂Ph) react with the substituted hydrazines RCONHNHR′(R = Ph, p-ClC₆H₄, p-MeC₆H₄, p-MeOC₆H₄, Et, Prⁿ, Prⁱ, or CH₂Ph; R′= Ph, p-ClC₆H₄,p-MeOC₆H₄, 1-C₁₀H₇, or Me) to give the imido-complexes [MoCl₂(NR′)(R′N₂COR)(PR″₃)]. The crystal and molecular structure of the title complex has been determined from single-crystal X-ray diffractometer data. The crystals are monoclinic with a= 8.995, b= 19.090, c= 17.860 Å, β= 104.15°, space group P2₁/c, and Z= 4. The structure has been solved by Patterson and Fourier methods, and least-squares refinement using 2 279 independent observed reflections has reached R= 0.066. The co-ordination geometry is distorted octahedral. The metal–diazene chelate system is quite planar and bond lengths indicate considerable delocalisation within the chelate ring. In particular, the Mo–N length [1.984(8)Å] is shorter than the Mo–O length [2.110(7)Å] and this is taken to indicate partial double-bond character in the Mo–N bond. The remaining metal–ligand distances are Mo–N(imido) 1.726(9), Mo–Cl 2.393(4)(trans to P) and 2.406(3)(trans to N in chelate ring), and Mo–P 2.528(4)Å.