Synthesis and characterization of neutral iron(ii) and ruthenium(ii) complexes with the isocyanotriphenylborate ligand

Abstract

By reacting metal cyanide complexes with NaBPh₄ in the presence of acid at room temperature, a new class of neutral isocyanotriphenylborate-containing complexes trans-Ru(L)₄(CNBPh₃)₂ (L = pyridine, 1; 4-methylpyridine, 2; 4-tert-butylpyridine, 3), cis-Ru(bipy)₂(CNBPh₃)₂ (4, bipy = 2,2′-bipyridine) and cis-M(phen)₂(CNBPh₃)₂ (M = Ru, 5; M = Fe, 6; phen = 1,10-phenanthroline) have been synthesized. These new complexes are characterized by IR, UV spectroscopy and single-crystal X-ray diffractions. The electron withdrawing triphenylborate group on the isocyanide ligands has a pronounced effect on the photophysical properties of complexes 1–6 in comparison with other ruthenium(II) and iron(II) isocyanide complexes. The excitation energies corresponding to metal-to-ligand charge transfer (MLCT) shift to higher energies while the ³MLCT emissions are quenched at room temperature.