Abstract
The synthesis of W(NAr′)(NHC)(=CHR)(2,5-Me2pyr)2 (1; Ar′: 2,6-iPr2C6H3; NHC: 1,3-diisopropylimidazol-2-ylidene; 2,5-Me2pyr: 2,5-dimethylpyrrolide; R: CMe2Ph), W(NAr′)(NHC)(=CHR)(2,5-Me2pyr)(OC6F5) (2), W(NAr′)(NHC)(=CHR)(OSiPh3)2 (3), [W(NAr′)(NHC)(=CHR)(OSiPh3))(MeCN)+][B(ArF)4−] (4; B(ArF)4−: B(3,5-(CF3)2C6H3)4−), [W(NAr′)(NHC)(=CHR)(2,5-Me2pyr))+][B(ArF)4−] (5), [W(NAr′)(NHC)(=CHR)(OC6F5))(tBuCN)+][B(ArF)4−] (6), W(NAr′)(NHC)(=CHR)(OtBu)2 (7), [W(NAr′)(NHC)(=CHR)(OtBu)+][B(ArF)4−] (8), and W(NAr′)(NHC)(=CHR)(OCMe(CF3)2)2 (9) is described, and the reactivity of the complexes in olefin metathesis and cyclopolymerization is reported. The cationic complexes 4, 5, and 6 showed high productivity and activity in olefin metathesis reactions, with turnover numbers of up to 40 000 and turnover frequencies (TOF5min) of up to 31 s−1, and also substantial functional group tolerance toward esters, nitriles, alcohols, and sulfides, particularly in the cyclopolymerization of α,ω-diynes.
Tolerance is complex: High productivity and activity in olefin metathesis reactions, along with substantial functional group tolerance, was shown by cationic tungsten imido alkylidene N-heterocyclic carbene complexes.
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