"Simple" Carbonyls of Ruthenium: New Avenues from the Hieber Base Reaction.

A witches brew is an apt description of the mixture of carbonyl chlorides of ruthenium(II), which arise from the carbonylation of alcoholic solutions of commercially available hydrated ruthenium chloride "RuCl(3) small middle dotH(2)O". Recent studies by Lavigne et al. on [RuCl(2)COOH(CO)(2)](-), one of the key compounds in these catalytic "broths", have established that its formation is highly dependent on the conditions and the hydroxide source, and that the role of the chloride coligand is far from innocent. Related halide-free chemistry by Fachinetti et al., however, has revealed that there are intriguing and recurrent parallels between the two systems.