Synthesis and characterization of ruthenium(II) complexes bearing the bis(2-pyridylmethyl)amine ligand

Abstract

The reaction of [Ru(CO) 2Cl 2] n with bis(2-pyridylmethyl)amine (bpma) in refluxing ethanol followed by anion exchange yields two products: cis, fac-[Ru(bpma)(CO) 2Cl]PF 6 ( 1a, 71%) and trans, fac-[Ru(bpma)(CO) 2Cl]PF 6 ( 1b, 29%). Reaction of 1a with AgBF 4 in acetone, followed by acetonitrile and then anion exchange gave cis, fac-[Ru(bpma)(CO) 2(CH 3CN)](PF 6) 2 ( 2a). In the same way, 1b afforded trans, fac-[Ru(bpma)(CO) 2(CH 3CN)](PF 6) 2 ( 2b). Reaction of depolymerized [Ru(CO) 2Cl 2] n with bpma in ethanol at room temperature afforded cis, cis-[Ru(η 2-bpma)(CO) 2Cl 2] ( 3). In refluxing ethanol, 3 was converted to cis, fac-[Ru(bpma)(CO) 2Cl]Cl ( 1a-Cl). Heating 3 in chlorobenzene afforded 1b-Cl, exclusively; heating 3 in ethylene glycol gave mainly 1a-Cl. Heating 1a-Cl in ethanol resulted in no isomerization, but heating in chlorobenzene gave a mixture of 3 and 1b-Cl. Anion exchange for PF 6 with 1a-Cl and 1b-Cl afforded 1a and 1b, respectively, whereas anion exchange for BPh 4 afforded 1a- BPh 4. Compounds 1a, 1b, 2a and 3 have been structurally characterized.