Syntheses, characterizations and structures of ruthenium carbene and allenylidene complexes supported by 1,4,7-trimethyl-1,4,7-triazacyclononane (Me3tacn) ligands

Abstract

Treatment of ruthenium(II) precursor [(Me3tacn)Ru(dmso)Cl2] (Me3tacn = 1,4,7-trimethyl-1,4,7-triazacyclononane, dmso = dimethylsulfoxide) (1) with concentrated HCl in the presence of air afforded the ruthenium(III) complex [(Me3tacn)RuCl3·H2O] (2), from which a series of bipyridine-ruthenium(II) complexes [(Me3tacn)Ru(R-bpy)(H2O)](PF6)2 (bpy = 2,2′-bipyridine) was obtained according to our previous work. Reactions of [(Me3tacn)Ru(R-bpy)(H2O)](PF6)2 and 1,1-diphenylpropargyl alcohol afforded ruthenium(II) methoxycarbene complexes [(Me3tacn)(R-bpy)Ru=C(OMe)CHCPh2](PF6)2 (R = H,3; 4,4′-Me2, 5; 5,5′-Me2, 7; 4,4′-di-tBu, 9) and ruthenium(II) allenylidene complexes [(Me3tacn)(R-bpy)Ru=C=CCPh2](PF6)2 (R = H,4; 4,4′-Me2, 6; 5,5′-Me2, 8; 4,4′-di-tBu, 10) under different solvent conditions. Complexes 3‒10 were well characterized by infrared, UV/Vis, mass spectrometry, and NMR spectroscopies. The molecular structures of complexes 5, 7, and 8 have been also established by single-crystal X-ray diffraction.