Synthesis, characterization, and properties of some cyclopentadienyl molybdenum nitrosyl benzyl complexes

Reaction of CpMo(NO)(CH2Ph)Cl with Me2Mg, Ph2Mg, or PhCCLi reagents in THF affords the corresponding alkyl, aryl, or alkynyl CpMo(NO)(CH2Ph)R (R = hydrocarbyl) complexes as orange powders in good yields. Unlike related 16-electron CpMo(NO)R-2 complexes, these 18-electron species exhibit good thermal stability due to their eta (2)-benzyl-Mo interactions. Treatment of CpMo(NO)(CH2Ph)Cl with Na(DME)Cp provides dark green Cp2Mo(NO)(CH2Ph), whose solid-state molecular structure has been established by a single-crystal X-ray crystallographic analysis. The two Cp rings display different binding modes to the Mo atom, while the benzyl ligand is coordinated to the metal centre in an eta (1) fashion. The triflate complex, CpMo(NO)(CH2Ph)(OTf), is obtained by addition of AgOTf to the benzyl chloride precursor. The covalent Mo-OTf bond in this compound can be disrupted by the addition of Lewis bases (L) such as PPh3 or pyridine, leading to the corresponding [CpMo(NO)(CH2Ph)(L)][OTf] salts. Attempts to generate neutral benzylidene complexes by deprotonation of [CpMo(NO)(CH2Ph)(PPh3)][OTf] have not yet been successful.