A simple synthesis of trans-RuCl(CCR)(dppe)2 complexes and representative molecular structures

The five-coordinate complex [RuCl(dppe)(2)]OTf ([2]OTf) is obtained in high yield by the sequential reduction of RuCl3 center dot nH(2)O to RuCl2(PPh3)(3), subsequent phosphine substitution to give trans-RuCl2(dppe)(2) (trans-1) and finally chloride abstraction (AgOTf, CH2Cl2). The use of [2] OTf as an entry point to mono-acetylide complexes trans-RuCl(C CC6H4R-4)(dppe)(2) (3) is described, and represents an alternative route to the long-standing methods based on cis-RuCl2(dppe)(2) (cis-1), which is always prepared as a mixture with the more thermodynamically stable trans isomer when prepared by phosphine substitution reactions of RuCl2(dmso)(4). The molecular structures of [2]OTf, trans-RuCl(C CC6H4OMe-4)(dppe)(2) (3b), trans-RuCl(C=CC6H4Me-4)(dppe)(2) (3c) and trans-RuCl(C=CC6H4CO2Me-4)(dppe)(2) (3e) are described. A facile and reproducible synthesis of cis-1 is also reported. (C) 2009 Elsevier B.V. All rights reserved.