Reactions of co-ordinated ligands. Part 54. Synthesis of (1,2,3-η)-trans-butadienyl complexes by deprotonation or desilylation of cationic molybdenum 1,3-diene complexes; formation of η4-vinylketene complexes and crystal structures of [Mo{(1,2,3-η)-trans-CH2CHCCH2}(CO)2(η-C5Me5)], [Mo{η3-CH2CC(Me)CH2CO}(CO)2(η-C5Me5)] and [Mol{η4-CH2CHC(Me)CO}(CO)(η-C5Me5)]

摘要: One of the products reaction base Li[N(SiMe3)2] with [Mo(η4-C4H6)(CO)2(η-C5Me5)][BF4] is exo-orientated (1,2,3-η)-trans-butadienyl complex [Mo{(1,2,3-η)-trans-CH2CHCCH2}(CO)2(η-C5Me5)]. A single-crystal X-ray diffraction study latter has revealed that two adjacent π systems, allyl and CCH2 within butadienyl fragment are orthogonal to each other. This can be formed selectively in high yield by [NBun4]F cation [Mo{η4-CH2CHC(SiEt3)CH2}(CO)2(η-C5Me5)][BF4]. The desilylation also been used transform [Mo{η4-syn-CH(Ph)CHC(SiMe3)CH2}(CO)2(η-C5Me5)][BF4] into a mixture exo- endo-[Mo{(1,2,3-η)-trans-syn-CH(Ph)CHCCH2}(CO)2(η-C5Me5)]. An alternative synthetic route complexes was explored involving Li[Mo(CO)3(η-C5Me5)] CH2CC(Me)CH2Cl. In event an unusual cyclisation occurred leading formation crystallographically identified [Mo{η3-CH2[graphic omitted]O}(CO)2(η-C5Me5)]. Extended Huckel molecular orbital calculations on [Mo{(1,2,3-η)-trans-CH2CHCCH2}(CO)2(η-C5Me5)] using complete set crystallographic coordinates shows protons should occur end carbon ligand form cationic η3-vinylcarbene complex. However, protonation CF3SO3H affords vinylketene [Mo(OSO2CF3){η4-CH2CHC(Me)CO}(CO)(η-C5Me5)] structural identity which established analogue [Mol{η4-CH2CHC(Me)CO}(CO)(η-C5Me5)] obtained from triflate via metathesis. mechanisms these reactions discussed.