Ru alkylidene compounds bearing tridentate, dianionic ligands: Lewis acid activation and olefin metathesis

Abstract

The series of tridentate complexes of Ru-alkylidenes (L)Ru(CHPh)(SCH₂CH₂)₂E (E = O, L = SIMes 1, PCy₃2, E = S, L = SIMes 3, PCy₃4; E = PPh 7, L = PCy₃), (L)Ru(CHPh)(SC₆H₄)₂S (L = SIMes 5, PCy₃6), (L)Ru(CHPh) (OCH₂CH₂)₂O (L = SIMes 8, PCy₃9) were prepared and shown to react with one equivalent of BCl₃ to give the complexes (L)Ru(CHPh)Cl[E(CH₂CH₂S)₂BCl₂] (E = O, L = SIMes 10, PCy₃11, E = S, L = SIMes 12a/b, PCy₃13, E = PPh, L = PCy₃16) and (L)Ru(CHPh)(SC₆H₄)₂O (L = SIMes 14, PCy₃15). In the case of 1 and 2 reaction with two equivalents of BCl₃ affording the corresponding cation via chloride abstraction. These cations coordinate MeCN to give the six coordinate Ru cation salts [(L)Ru(CHPh)(NCMe)(O(CH₂CH₂S)₂BCl₂)][BCl₄] L = SIMes 17, PCy₃18). The generated five coordinate cations derived from 2–9via addition of two equivalents of BCl₃ were evaluated in standard preliminary tests for olefin metathesis catalysis.