Synthesis, structure, spectroscopic properties, electrochemistry, and DFT correlative studies of trans-[Ru(P-P)2Cl2] complexes

Abstract

Five trans-[Ru(P-P)2Cl2] complexes were prepared by reacting RuCl2(PPh3)3 with P-P ligands {P-P = 3-hexyl-1,3-bis(diphenylphosphino)propane (hdppp) (1); = 1,3- bis(diphenylphosphino)propane (dppp) (2); = 1,2-bis(diphenylphosphino)ethane (dppe) (3); 1.1′-bis(diphenylphosphino)methane (dppm) (4); 1,2-bis(diphenylphosphino)ethylene (depe) (5)}. The complexes were characterized by an elemental analysis, IR, 1H, 13C and 31P{1H}NMR, FAB-MS and TG/DTA. These Ru(II) complexes showed Ru(III)/Ru(II) quasireversible redox couple. The molecular structures of the complexes 1 and 3 were determined by X-ray crystallography, and their spectroscopic properties were studied. Another polymorph of 3 was reported in literature, the reported polymorph of 3 in this work crystallizes in P1 space group, whereas, the previously reported polymorph crystallizes in C2/c space group. The two complexes adopt a distorted trans octahedral coordination and ruthenium(II) ions are located on a crystallographic centre of symmetry. Based on the optimized structures, computational investigations were carried out in order to determine the electronic structures of the complexes. The electronic spectra of 1 and 1+ in dichloromethane were calculated with the use of time-dependent DFT methods, and the electronic spectra of the transitions were correlated with the molecular orbitals of the complexes. © 2013 Elsevier Ltd. All rights reserved.