Synthesis, structure and reactivity of molybdenum imido and oxo complexes. X-ray structure of MoCl 3(NAr)L 2 (Ar=2,6-diisopropyl phenyl; L=N-2',6'-diisopropyl phenyl-2,5-dimethyl benzamide)

Abstract

The reaction of MoCl 4(O) with ArNCO (Ar=2,6- i Pr 2Ph) afforded a series of paramagnetic oxo and imido Mo(V) complexes depending on the nature of the solvent used in each case. A X-ray study of one of this complexes, MoCl 3(NAr)L 2 (L=N-2',6'-diisopropyl phenyl-2,5-dimethyl benzamide) ( 3) (orthorhombic, P2 12 12 1, a=10.8194(8), b=23.528(2), c=23.914(2) Å, V=6087.4(9) Å 3, Z=4) supports a pseudooctahedral structure with the imido group occupying one of the axial positions. Reduction of Mo(VI) and Mo(V) oxo and imido complexes in the presence of three equivalents of P(OMe) 3 yields complexes MoCl 2(E)[P(OMe) 3] 3 (E=O ( 5), NAr ( 6)). Spectroscopic data of 5 and 6 show a pseudooctahedral structure with the oxo or imido ligand occupying one of the axial positions and the three phosphite ligands placed in the equatorial plane. Complexes 5 and 6 react with 3,3-diphenylcyclopropene leading to olefin complexes which are thermally unstable and decompose at room temperature affording 1,1,6,6 tetraphenyl hexatriene, presumably via intermediate molybdenum vinyl alkylidenes.