Synthesis and characterization of novel tetradentate ruthenium complexes of a pyridine-o-phenylenediamine based chelate ligand

Abstract

The synthesis of the new complexes [cis-Ru(N,N′-bis-(2-pyridylmethyl)-o-phenylenediamine)(Cl)(DMSO)](Cl), [cis-Ru(N,N′-bis-(2-pyridylmethyl)-o-phenylenediamine)(MeCN)2](OTf)2 and [cis-Ru(N,N′-bis-(2-pyridylmethyl)-o-phenylenediamine)(PhCN)2](OTf)2 is reported. The ligand, N,N′-bis-(2-pyridylmethyl)-o-phenylenediamine, was complexed to ruthenium using the ruthenium precursor, RuCl2(DMSO)4, to yield the intermediate complex [cis-Ru(N,N′-bis-(2-pyridylmethyl)-o-phenylenediamine)(Cl)(DMSO)](Cl). The metathesis of DMSO and chloride ligands from [cis-Ru(N,N′-bis-(2-pyridylmethyl)-o-phenylenediamine)(Cl)(DMSO)](Cl) was carried out in the appropriate nitrile solvent with 2 equivalents of AgOTf to yield the complexes [cis-Ru(N,N′-bis-(2-pyridylmethyl)-o-phenylenediamine)(MeCN)2](OTf)2 and [cis-Ru(N,N′-bis-(2-pyridylmethyl)-o-phenylenediamine)(PhCN)2](OTf)2. Both complexes were characterized by single crystal XRD. [cis-Ru(N,N′-bis-(2-pyridylmethyl)-o-phenylenediamine)(MeCN)2](OTf)2 and [cis-Ru(N,N′-bis-(2-pyridylmethyl)-o-phenylenediamine)(PhCN)2](OTf)2 both possess the hypothetical characteristics of homogeneous hydrogenation catalysts that are anticipated to be acid- water- and temperature stable, and have the potential to be tested as such.