Reactions of [Ru(bipy)(CO)2Cl2] in aqueous HX and HX–HNO3 solutions (X = F, Br or I; bipy = 2,2′-bipyridine)

Abstract

Aqueous halogen acids HBr and HI have been used to direct exchange of the chlorides in [Ru(bipy)(CO)₂Cl₂](bipy = 2,2′-bipyridine) at elevated temperatures (160–200 °C). Reaction of cis(CO), trans(Cl)-[Ru(bipy)(CO)₂Cl₂] with HBr and HI produced the corresponding cis(CO),trans(Br)-[Ru(bipy)(CO)₂Br₂]1 and cis(CO),trans(I)-[Ru(bipy)(CO)₂I₂]2. A similar reaction was not observed with the weaker (aqueous) acid HF. Addition of HNO₃ as a nitrosyl source in the acid solution led to formation of nitrosyl complexes [Ru(bipy)(NO)X₃](X = F, Cl, Br or I). In the case of HBr–HNO₃ or HI–HNO₃ addition of nitrosyl was most probably accompanied by complete exchange of chlorides giving [Ru(bipy)(NO)X₃](X = Br or I), while in HF–HNO₃ no exchange was observed. In the latter case a mixed-halide complex [Ru(bipy)(NO)Cl₂F]3 was obtained. By using HBr–HNO₃ solutions and extended reaction times, nitrido-bridged [(H₂O)Br₂(bipy)Ru–N–Ru(bipy)Br₃]4 was formed at 240 °C probably via a nitrosyl intermediate. The complexes were characterised by IR, NMR spectroscopy and single-crystal X-ray crystallography.