Reactivity of Cyclomanganated 2-Phenylpyridine Derivatives toward Organolithium Reagents. Synthesis of Novel Chelated Tricarbonyl(η3-benzyl)manganese(I) Complexes

Abstract

Ortho-manganated 2-arylpyridine and -quinoline derivatives were treated with aryllithium reagents and subsequently with alkyl triflates to yield air-stable chelated (η3-benzyl)tricarbonylmanganese complexes. Addition of PhLi to the cyclomanganated complex of 2-phenylpyridine [NC5H4−C6H4−Mn(CO)4], 1, followed by methylation with MeOTf afforded a red air-stable chelated η3-benzyl, tricarbonyl{2-[(1,2-η2),κCα-2-(phenylmethoxymethylene)phenyl]pyridine- κN}manganese(I), complex 4a. The molecular structure of 4a was established by single-crystal X-ray diffraction analysis. The study of this structure indicates a helical shape in which the manganese center adopts an octahedral configuration. Spectroscopic analysis indicates that the addition of the aryllithium reagent to 1 generates a new temperature- and air-sensitive benzoylmanganate species. The latter and other anionic acylmanganese species generated from different substrates readily decompose above a temperature of 0 °C to yield ketones and a formal [Mn(CO)...