Syntheses, Crystal Structures, and Conversion of Three Linkage Isomers of Di-2-pyridyl Ketone in Dichlorobis(dimethyl sulfoxide-S)-ruthenium(II) and Chlorobis(dimethyl sulfoxide-S)ruthenium(II) Complexes: [RuCl_2(dpk-(kappa)~2N,O)(dmso-S)_2], [RuCl_2

摘要

The reaction between trans-[RuCl_2(dmso-S)_4] (dmso = dimethyl sulfoxide) and di-2-pyridyl ketone (dpk) in H_2O at room temperature afforded trans(Cl),cis(S)-[RuCl_2(dpk-(kappa)~2N,O)(dmso-S)_2] (1) in high yield, while the reaction between cis(Cl),fac(S)-[RuCl_2(dmso-S)_3(dmso-O)] and dpk in EtOH-DMSO at reflux afforded cis(Cl),cis(S)-[RuCl_2-(dpk-(kappa)~2N,N')(dmso-S)_2] (2). Reaction of 1 with Ag~+ and OH~- afforded the one-dimensional Ru-Ag coordination polymer trans(Cl),cis(S)-[AgRuCl_2(dpk-OH-(kappa)~3N,O,N')(dmso-S)_2]_n (3), which, as shown by X-ray crystallographic analysis, was in an "arrested" state of chloride ion abstraction. Reaction of 3 in DMSO afforded a mixture of two isomers containing dpk-OH-(kappa)~3N,O,N': trans(Cl,O),cis(S)- and cis(Cl,O),cis(S)-[RuCl(dpk-OH-(kappa)~3N,O,N')(dmso-S)_2] (4a and 4b, respectively). The trans(Cl,O),cis(S)-isomer 4a was selectively synthesized by reaction of 1 with OH~- in H_2O, while the cis(Cl,O),cis(S)-isomer 4b was selectively synthesized by reaction of 2 with OH~- in H_2O. The isomerization reaction between 4a and 4b in DMSO solution was found to be reversible, and 4b was favored over 4a, with K_(4ab) = [4b]/[4a] = 1.5 ± 0.1. The crystal structures of 1 and 2 showed that the geometry of the RuCl_2(dmso-S)_2 unit caused selective formation of the (kappa)~2N,O- and (kappa)~2N,N'-coordination modes of the dpk ligand. In 4a, the flexibility of the (kappa)~3N,O,N'-coordi-nation mode of the (dpk-OH)~- ligand mitigates the steric hindrance caused by the RuCl(dmso-S)_2~+ unit.