The carboxylate-bridged polymer[{Ru2[µ-η2-OC(R)O]2(CO)4}n](R = H, Me or Et) as a synthon in the synthesisof dinuclear phosphorus pyridyl-, quinolyl- and bipyridyl-bridgedderivatives of ruthenium(I)

Treatment of [{Ru 2 [µ-η 2 -OC(R)O] 2 (CO) 4 } n ] or its acetonitrile adduct [Ru 2 {µ-η 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 {µ-η 2 -OC(R)O} 2 (CO) 4 (PPh 2 R′) 2 ] (R′ = pyridyl, quinolyl or bipyridyl) in which the PPh 2 R′ ligands are monodentate, co-ordinating axially through the phosphorus donor atoms, as established X-ray crystallographically for [Ru 2 {µ-η 2 -OC(Me)O} 2 (CO) 4 (dppy) 2 ]. On the other hand reaction of [{Ru 2 [µ-η 2 -OC(R)O] 2 (CO) 4 } n ] with 2 molar equivalents of dppy or dpquin in toluene under reflux in the presence of NH 4 PF 6 and under a slight pressure of carbon monoxide afforded products of the type [Ru 2 {µ-η 2 -OC(R)O}(CO) 4 (µ-dppy) 2 ]PF 6 or [Ru 2 {µ-η 2 -OC(R)O}(CO) 4 (µ-dpquin) 2 ]PF 6 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 {µ-η 2 -OC(H)O}(CO) 4 (µ-dppy) 2 ]PF 6 . Reaction of [{Ru 2 [µ-η 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 {µ-η 2 -OC(R)O}(CO) 2 (µ-dpbipy) 2 ]PF 6 , the structure of [Ru 2 {µ-η 2 -OC(Me)O}(CO) 2 (µ-dpbipy) 2 ]PF 6 being established X-ray crystallographically.