Water-induced isomerization of CpW(NO)(o-tolyl)2 to CpW(O)(N-o-tolyl)(o-tolyl) and related chemistry

Article abstract of DOI:10.1021/om00012a026

Treatment of a THF solution of CpW(NO)(o-tolyl)₂ (1) with H₂O affords a structural isomer of 1, namely CpW(O)(N-o-tolyl)(o-tolyl) (2), in 30% isolated yield as well as the expected product, CpW(O)₂(o-tolyl) (3), in low isolated yield (10%). Complexes 2 and 3 are formed in a ratio of approximately 1:1 upon treatment of a C₆D₆ solution of 1 with D₂O. Similar treatment of 1 with ¹⁸OH₂ results in the production of unlabeled complex 2, thereby establishing the intramolecular nature of the water-catalyzed isomerization of 1 to 2. The characteristic reactivity of CpW(NO)(o-tolyl)₂ toward various classes of reagents has been investigated to determine if the conversion of 1 to 2 can be effected with reagents other than water. In general, this reactivity has been found to be similar to that exhibited by other Cp′W(NO)R₂ (Cp′ = Cp or Cp*; R = alkyl or aryl) complexes, and treatment of 1 with reagents other than water does not result in isomerization of the organometallic reactant. The isomerization is also dependent upon the nature of the Cp ligand, the metal, and the aryl groups as evidenced by the fact that treatment of the related diaryl complexes, CpW-(NO)(p-tolyl)₂, CpW(NO)Ph₂, CpMo(NO)(o-tolyl)₂, and Cp*W(NO)(o-tolyl)₂, with water does not result in the production of their arylimido oxo structural isomers. Consequently, the water-induced isomerization of 1 to 2 remains a unique chemical process. Crystals of CpW-(NO)(o-tolyl)₂ (1) and CpW(O)(N-o-tolyl)(o-tolyl) (2) have been subjected to X-ray crystallographic analyses.