Reactions of co-ordinated ligands. Part 17. The synthesis and reactions of cationic η5-indenyl- and η-cyclopentadienyl-molybdenum complexes containing 1,3-diene and acetylene ligands

Abstract

Reaction of [{Mo(CO)₃(η⁵-C₉H₇)}₂] with Ag[BF₄] in MeCN affords [Mo(CO)₂(NCMe)₂(η⁵-C₉H₇)][BF₄], which reacts with L = P(OMe)₃, Ph₂PCH₂CH₂PPh₂, buta-1,3-diene, isoprene, 2,3,-dimethylbuta-1,3-diene, or trans-penta-1,3,diene to form [Mo(CO)₂L₂(η⁵-C₉H₇)][BF₄]; alternatively, the 1,3-diene complexes, including those of cyclohexa-1,3,-diene and cyclo-octatetraene, can be formed directly from [{Mo(CO)₃(η⁵-C₉H₇)}₂], Ag[BF₄], and the 1,3-diene. Reaction of Na[BH₄] or 1-morpholinocyclopent-1-ene with the 1,3-diene cations results in regio-selective formation of the anti-substituted η³-allyl complexes. Treatment of [Mo(CO)₂(NCMe)₂(η⁵-C₉H₇)][BF₄] with acetylenes or reaction of [{Mo(CO)₃(η⁵-C₉H₇)}₂] or [{Mo(CO)₃(η⁵-C₅H₅)}₂] with Ag[BF₄] and the respective acetylene in CH₂Cl₂ affords the 16-electron cations [Mo(CO)(η²-RC₂R′)₂L′][BF₄](R = R′= Me or Ph; R = H, R′= Me; R = H, R′= Bu^t; L′=η⁵-C₉H₇ or η-C₅H₅). Reaction of these complexes with excess of P(OMe)₃ gives [Mo(η²-RC₂R′){P(OMe)₃}₂L′][BF₄]. In contrast, with the bis(acetylene) cations the acetylene in the latter complexes readily undergoes propeller rotation.