Soluble ruthenium carbonyl complexes containing new sterically hindered bipyridine ligands

The synthesis, characterization and reactivity of bipyridyl ruthenium carbonyl complexes of the type Ru(NN)(CO)(2)Cl-2 [where NN = 4,4'-(t)Bu(2)-2,2'-bpy (bpy*, a); 6,6'-Me(2)-4,4'-(t)Bu(2)-2,2'-bpy (dmbpy*, b); 6,6'-Ph(2)-4,4'-(t)Bu(2)-2,2'-bpy (dpbpy*, c)] is reported together with the synthesis and characterization of Ru(dpphen)(CO)(2)Cl-2 [where dpphen = 2,9-Ph(2)-1,10-phen, d]. When NN is bpy* or dmbpy*, the cis-carbonyl, trans-chloro isomer is obtained, whereas when NN is dpbpy* or dpphen the cis-carbonyl, cis-chloro isomer is the predominant product.