Organoimido complexes of tungsten-(VI) and-(V): correlation between relativeorientation of π-donor ligands and electron configuration of themetal

The high-yield synthesis of the monomeric five-co-ordinate arylimido complex [WCl 3 (NPh)(OC 6 H 3 Pr i 2 -2,6)] was achieved starting from [{WCl 3 (NPh)} 2 (µ-Cl) 2 ]. The adducts [WCl 3 (NPh)(OC 6 H 3 Pr i 2 -2,6)L] (L = tetrahydrofuran, pyridine (py) or 4-tert-butylpyridine) of the monoalkoxide have been synthesized and the constitution of the pyridine adduct determined by X-ray crystallography. The reduction of the monoalkoxide with 1 equivalent of sodium amalgam in the presence of pyridine or triethylphosphine leads to the paramagnetic adducts [WCl 2 (NPh)(OC 6 H 3 Pr i 2 -2,6)L 2 ] (L = py or PEt 3 ) which were characterized. A trans configuration was found for the two chlorine atoms and the two σ-donor ligands in the structure analysis. Reorganization of the two π-donor ligands (aryloxide and NPh) from a cis arrangement in the complex with d 0 electron configuration to a trans arrangement in the d 1 configurated complexes is found and verified by X-ray diffraction analyses.

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