Synthesis and catalytic reactivity of mononuclear substituted tetramethylcyclopentadienyl molybdenum carbonyl complexes

Abstract

The reactions of five dinuclear carbonyl complexes [(η ⁵-C₅Me₄R)Mo(CO)₃]₂ [R = allyl, ⁿBu, ^tBu, Ph, Bz] with I₂ in chloroform solution gave the corresponding mononuclear substituted tetramethylcyclopentadienyl molybdenum carbonyl complexes [(η ⁵-C₅Me₄R)MoI(CO)₃] [R = allyl (1), ⁿBu (2), ^tBu (3), Ph (4), Bz (5)]. The molecular structures of complexes 2, 3 and 5 were determined by X-ray diffraction analysis. The results show that the substituent in the ring can directly affect the Mo–I bond distances; the more sterically hindered the substituent, the longer the Mo–I bond. Friedel–Crafts reactions of aromatic compounds with a variety of alkylation reagents catalyzed by the complexes showed that all of these mononuclear molybdenum carbonyl complexes have catalytic activity in Friedel–Crafts alkylation reactions. Indeed, compared with traditional catalysts, these mononuclear metal carbonyl complexes have obvious advantages such as higher activities, mild reaction conditions, high selectivity, simple post-processing, and environmentally friendly chemistry.