Synthesis of Ether-Functionalized and Sterically Demanding Molybdenum Alkylidyne Complexes

Abstract

The synthesis of ether-functionalized molybdenum benzylidyne complexes [ArC≡Mo{OC(CF3)2Me}3] (6, Ar = para-methoxyphenyl; 7, Ar = 2,4,6-trimethoxyphenyl) and of the sterically demanding benzylidyne complex [{2,4,6-(i-Pr)3C6H2}C≡Mo{OC(CF3)2Me}3] are presented, together with their spectroscopic characterization, molecular structures, and catalytic activity in alkyne metathesis. Complexes 6 and 7 feature intermolecular contacts between the para-methoxy group and the molybdenum center that give rise to 1D-polymeric structures in the solid state. The preparation of other functionalized alkylidyne complexes, [ArC≡Mo{OC(CF3)2Me}3] (Ar = 2-(i-PrO)C6H4, 8-MeO-Naph, 2,6-(i-Pr)2C6H3), was also attempted, but only the acyl precursors [ArC(═O)Mo(CO)5]− could be isolated. The synthesis of the molybdenum acyl complexes was challenging, and appropriate alternative protocols were developed.