The carboxylate-bridged polymer [{Ru-2[mu-eta(2)-OC(R)O](2)(CO)(4)}(n)] (R=H, Me or Et) as a synthon in the synthesis of dinuclear phosphorus pyridyl-, quinolyl- and bipyridyl-bridged derivatives of ruthenium(I)

Treatment of [{Ru-2[mu-eta(2)-OC(R)O](2)(CO)(4)}(n)] or its acetonitrile adduct [Ru-2{mu-eta(2)-OC(R)O}(2)(CO)(4)(MeCN)(2)] (R = H, Me or Et) with a two-fold molar equivalent of the phosphorus-nitrogen ligands 2-diphenylphosphinopyridine (dppy), 2-diphenylphosphinoquinoline (dpquin) and 6-diphenylphosphino-2,2'-bipyridine (dpbipy) in alcohol under reflux resulted in the formation of dinuclear products of the type [Ru-2{mu-eta(2)-OC(R)O}(2)(CO)(4)(PPh2R')(2)] (R' = pyridyl, quinolyl or bipyridyl) in which the PPh2R' ligands are monodentate, co-ordinating axially through the phosphorus donor atoms, as established X-ray crystallographically for [Ru-2{mu-eta(2)-OC(Me)O}(2)(CO)(4)(dppy)(2)]. On the other hand reaction of [{Ru-2[mu-eta(2)-OC(R)O](2)(CO)(4)}(n)] with 2 molar equivalents of dppy or dpquin in toluene under reflux in the presence of NH4PF6 and under a slight pressure of carbon monoxide afforded products of the type [Ru-2{mu-eta(2)-OC(R)O}(CO)(4)(mu-dppy)(2)]PF6 or [Ru-2{mu-eta(2)-OC(R)O}(CO)(4)(mu-dpquin)(2)]PF6 in which the dppy or dpquin ligands adopt the bridging co-ordination mode, this mode of co-ordination being confirmed through a crystal structure determination on [Ru-2{mu-eta(2)-OC(H)O}(CO)(4)(mu-dppy)(2)]PF6. Reaction of [{Ru-2[mu-eta(2)-OC(R)O](2)(CO)(4)}(n)] with dpbipy in n-butanol under reflux likewise afforded products, isolated as their hexafluorophosphate salts, in which the phosphorus-nitrogen ligands are bridging, viz. [Ru-2{mu-eta(2)-OC(R)O}(CO)(2)(mu-dpbipy)(2)]PF6, the structure of [Ru-2{mu-eta(2)-OC(Me)O}(CO)(2)(mu-dpbipy)(2)]PF6 being established X-ray crystallographically.