New [Mo(η3-allyl)(CO)2L3]+ complexes with monodentate or tridentate nitrogen-donor ligands

Abstract

Cationic complexes [Mo(η³-allyl)(CO)₂L₃]⁺ (L₃ = either nitrogen-donor tridentate ligand or three monodentate ligands) were prepared in high yield and under mild conditions using as precursors either the triflato complex [Mo(η³-allyl)(OTf)(CO)₂(NCMe)₂] or the combination of the chloro complex [Mo(η³-allyl)Cl(CO)₂(NCMe)₂] and the salt NaBAr′₄ (Ar′ = 3,5-bis(trifluoromethyl)phenyl). The tridentate ligands employed were 2,2′:6′,2′-terpyridine (terpy) and cis,cis-1,3,5-cyclohexanetriamine (CHTA), whereas the monodentate ligands imidazole (im) and 3,5-dimethylpyrazole (dmpz) were chosen. In order to stabilize the labile intermediates, an excess of acetonitrile was used in most of the syntheses. However, the pyrazole complex was prepared through a nitrile-free route to avoid reactions at the coordinated nitrile. The solid state structures of [Mo(η³-methallyl)(CO)₂(terpy)]OTf (2), [Mo(η³-methallyl)(CO)₂(CHTA)]BAr′₄ (3), [Mo(η³-methallyl)(CO)₂(NCMe)₃]BAr′₄ (4), [Mo(η³-allyl)(CO)₂(im)₃]OTf (5) and [Mo(η³-allyl)(CO)₂(dmpz)₃]BAr′₄ (6) were determined by means of single-crystal X-ray diffraction.