Selective formation of cis(X)- and trans(X)-Ru(dmbpy)(CO)(2)X-2 complexes (X = Cl, Br, I, SCN) from monomeric and dimeric Ru-mono(dmbpy) carbonyl complexes (dmbpy = 4,4 '-dimethyl-2,2 '-bipyridine)

Aqueous hydrogen halides HX (X = Cl, Br, I) are shown to be excellent halog en sources for the synthesis of a series of halogen-containing ruthenium mo no(2,2'-bipyridine) carbonyl complexes Ru(dmbpy)(CO)(2)X-2 (dmbpy = 4,4'-di methyl-2,2'-bipyridine), as well as effective reagents for the attack of th e Ru-Ru bond in the dimer [Ru(dmbpy)(CO)(2)Cl](2). Selective syntheses were established for both cis- and trans-halogen complexes in the case of Cl- a nd of Br-containing derivatives. but the only stable isomer containing iodi ne was trans(I)-Ru(dmbpy) (CO)(2)I-2. The failure to obtain the cis isomer was probably due to sterical effects. Furthermore, a novel S-bound trans(SC N) analogue was synthesized and structurally characterized. In all experime nts, the reaction conditions selected led to complete halogen exchange; no mixed halogen or pseudohalogen complexes were detected.