Mono(2,2′‐bipyridyl)RuII Complex with Four Dimethyl Sulfoxide Ligands as Precursor for cis‐Bis‐heteroleptic RuII Complex: Syntheses, Structures, and Substitution Reactions.

The dication complex trans(O,S)‐[Ru(bpy)(dmso‐O)2(dmso‐S)2](OTf)2 [1·(OTf)2; bpy = 2,2′‐bipyridyl; dmso = dimethyl sulfoxide; OTf– = CF3SO3–] was obtained from the reaction of cis(Cl),cis(S)‐[RuCl2(bpy)(dmso‐S)2] with Ag(OTf) in DMSO. The crystal structure of 1·(OTf)2 revealed two labile dmso‐O ligands and two less‐labile dmso‐S ligands positioned cis to each other. In DMSO, the equatorial dmso‐O in 12+ equilibrates with its linkage isomer dmso‐S to fac(S)‐[Ru(bpy)(dmso‐O)(dmso‐S)3]2+ [1iso2+] ([1iso2+]/[12+] = 3:97 at 298 K and 33:67 at 373 K). The linkage isomerization kinetic parameters, determined by 1H NMR, were ΔH = 22(1) kJ mol–1 and ΔS = 52(2) J mol–1 K–1. The two O‐bonded dmso ligands of 1·(OTf)2 were easily solvolyzed in MeCN to form trans(NMeCN,S)‐[Ru(bpy)(MeCN)2(dmso‐S)2](OTf)2 [2·(OTf)2]. Moreover, the reaction of 1·(OTf)2 with 1,10‐phenanthroline (phen) in acetone afforded cis‐[Ru(bpy)(phen)(dmso‐S)2](OTf)2 [3·(OTf)2] in very good yield (95 %) and excellent purity. 1·(OTf)2 was efficiently synthesized. In DMSO, the equatorial dmso‐O reversibly isomerizes into the S‐bonded form, 1iso·(OTf)2. In MeCN, both O‐bonded dmso ligands in 12+ are selectively replaced to form 2·(OTf)2. Finally, the reaction of 1·(OTf)2 with phen in acetone affords the cis‐bis‐heteroleptic complex 3·(OTf)2 in good yield. [ABSTRACT FROM AUTHOR]