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

Aqueous halogen acids HBr and HI have been used to direct exchange of the chlorides in [Ru(bipy)(CO)(2)Cl-2] (bipy = 2,2'-bipyridine) at elevated temperatures (160-200 degrees C). Reaction of cis(CO),trans(Cl)-[Ru(bipy)(CO)(2)Cl-2] with HBr and HI produced the corresponding cis(CO),trans(Br)-[Ru(bipy)(CO)(2)Br-2] 1 and cis(CO),trans(I)-[Ru(bipy)(CO)(2)I-2] 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)X(3)] (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)X(3)] (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-HNO, solutions and extended reaction times, nitrido-bridged [(H2O)Br-2(bipy)Ru-N-Ru(bipy)Br-3] 4 was formed at 240 degrees C probably via a nitrosyl intermediate. The complexes were characterised by IR, NMR spectroscopy and single-crystal X-ray crystallography.