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′= But; 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.