| Since its discovery, catalytic olefin metathesis has been used as a powerful tool for the synthesis of a variety of molecules. Over the last 20 years research in this area has received enormous attention in the development of new catalysts and applications. The vast majority of the ruthenium based catalysts developed have been modifications to the Grubbs Catalyst type architecture. The research presented herein focuses on the development of new olefin metathesis catalysts bearing tridentate, dianionic ligands and their activation with Lewis acids.;Complexes [(PPh3)2Ru(SCH2CH2) 2O] and [(PPh3)2Ru(SC6H4) 2O] were synthesized from (PPh3)3RuCl2 and the corresponding dilithio-dithiolate salt or from (PPh3) 4RuH2 and the corresponding dithiol. These complexes were shown to react with BCl3 forming complexes [(PPh3) 2RuCl(Cl2B(SCH2CH2)2O)] and [(PPh3)2RuCl(Cl2B(SC6H 4)2O)].;Complexes of the general structure [LRu(CHPh)(SC6H4) 2O] and [LRu(CHPh)(XCH2CH2)2E] where L = PCy3, SIMes, X = O, S, and E = O, S, PPh were prepared by ligand exchange with Grubbs I and II. Alternatively, complexes [LRu(CHPh)(SC 6H4)2O] and [LRu(CHPh)(SCH2CH 2)2E] where L = PCy3, SIMes and E = O, S were synthesized independently of Grubbs Catalyst by the reaction of dithioacetals with Ru(0) sources. These complexes proved to be inactive for catalytic olefin metathesis.;The addition of BCl3 to these complexes resulted in the formation of new 6-coordinate ruthenium alkylidene complexes of the general formula [LRuCl(CHPh)(Cl2B(SC6H4)2O)] and [LRuCl(CHPh)(Cl2B(XCH2CH2)2E)] where L = PCy3, SIMes, X = O, S, and E = O, S, PPh. These complexes also proved to be inactive for olefin metathesis. The addition of a second equivalent of BCl3 results in the formation of 5 coordinate cationic ruthenium species of the general formula [LRu(CHPh)(Cl2B(SC 6H4)2O)][BCl4] and [LRu(CHPh)(Cl 2B(XCH2CH2)2E)][BCl4] where L = PCy3, SIMes, X = O, S, and E = O, PPh.;These cationic species proved to be active for a variety of olefin metathesis reactions including ring closing metathesis (RCM), ring opening metathesis polymerization (ROMP) and cross metathesis (CM). |
