111997-40-1Relevant articles and documents
Tungsten and molybdenum alkylidyne complexes containing bulky thiolate ligands
Murdzek, John S.,Blum, Lauren,Schrock, Richard R.
, p. 436 - 441 (1988)
Complexes of the type Mo(C-t-Bu)(TMT)3 and Mo(C-t-Bu)(TIPT)3 (TMT = 2,4,6-trimethylbenzenethiolate; TIPT = 2,4,6-triisopropylbenzenethiolate) can be prepared by adding 3 equiv of LiSAr (SAr = TMT or TIPT) to Mo(C-t-Bu)Cl3(dme). The TMT derivative is believed to be dimeric on the basis of NMR spectra. Reactions between M(C-t-Bu)Cl3(dme) (M = Mo or W), ArSH, and NEt3 yield complexes of the type [Et3NH][M(C-t-Bu)(SAr)3Cl]. W(C-t-Bu)(SAr)3 complexes can be prepared by removing chloride ion from the [Et3NH][W(C-t-Bu)(SAr)3Cl] species with zinc chloride. M(C-t-Bu)(SAr)3 complexes do not react with 3-hexyne, 2-butyne, or phenylacetylene, and only minute traces of 3-heptyne metathesis products are observed after 3 days at 25°C. The reaction between W(C3Me3)Cl3 and LiTIPT yields W(C3Me3)(TIPT)3 (in situ), the reaction between W(C3Me3)Cl3, TIPTH, and NEt3 (or that between W(C3Me3)(TIPT)3 and Et3NHCl) gives [Et3NH][W(CMe)(TIPT)3Cl], and the reaction between the η3-cyclopropenyl complex W(C3-t-BuMe2)Cl3(py)2 and LiTMT yields a mixture of W(CMe)(TMT)3(py) and W(C-t-Bu)(TMT)3(py). Both Mo(CPr)(TIPT)3 and W(CMe)(TIPT)3 are stable and isolable. We conclude from these studies that M(CR)(SAr)3 complexes react too slowly with ordinary acetylenes to be active catalysts, either because coordination of sulfur (in a dimer) competes effectively with coordination of the acetylene or because the metal is simply not electrophilic enough, or both.
