Syntheses and Characterization of a Pair of Isomers of Heteroleptic Bis(Bidentate) Ruthenium(II) Complexes with Two Different Monodentate Ligands

Abstract

Twoi somerso fh eteroleptic bis(bidentate) ruthenium(II) complexes with dimethyl sulfoxide (dmso) and chloride ligands, trans(Cl,N bpy )-and trans(Cl,N Hdpa )-[Ru(bpy)Cl-(dmso-S)(Hdpa)] + (bpy:2 ,2'-bipyridine;H dpa:d i-2-pyridylamine), are synthesized. This is the first reporto nt he selective synthesis of ap air of isomers of cis-[Ru(L)(L')XY] n + (L ¼ 6 L':bidentate ligands;X¼ 6 Y: monodentate ligands). The structures of the ruthenium(II) complexes are clarified by means of X-ray crystallography,a nd the signals in the 1 HNMR spectra are assignedb ased on 1 H-1 HC OSY spectra.T he colors of the two isomers arec learly different in both the solids tate and solution:t he trans(Cl,N bpy )i somer has ad eep red color, whereast he trans(Cl,N Hdpa )i somer is yellow.A lthough both complexes have intense absorption bands at l % 440-450 nm, only the trans(Cl,N bpy )i somer hasashoulder band at l % 550 nm. DFT calculations indicate that the LUMOs of both isomers are the p*o rbitals in the bpy ligand, and that the LUMO level of the trans(Cl,N bpy )i somer is lower than that of the trans(Cl,N Hdpa )i somer due to the trans effect of the Cl ligand; thus resulting in the appearance of the shoulder band.T he HOMO levelsa re almost the same in both isomers.T he energy levels are experimentallys upported by cyclic voltammograms, in which these isomers have different reduction potentials and similaroxidation potentials.[a] Dr.M.T oyama Current address:O saka Prefecture University Collegeo fT echnology 26-12 Saiwaicho,

Colorimetric fluoride detection in dimethyl sulfoxide using a heteroleptic ruthenium(ii) complex with amino and amide groups: X-ray crystallographic and spectroscopic analyses

“…Both angles were consistent with those of the Hdpa ligand in previously reported Ru(II)-Hdpa complexes (25.9-48.2 ). 18,29,39,40 The difference between the two dihedral angles is likely caused by steric interactions between H 2 pia and the two Hdpa ligands. The N2 atom of the NH group in Hdpa(N1,N3) established contact with the O1 atom of H 2 pia (N2/O1 ¼ 3.036 Å; Fig.…”

“…Moreover, the dihedral angle for the other Hdpa(N4,N6) was signicantly smaller than that in the chloride salt (15.8 and 29.9 , respectively), and smaller than previously reported Ru(II)-Hdpa data (25.9 -48.2 ). 18,29,39,40 Generally, the bent conformation of Hdpa cuts off a p-conjugated system between two pyridyl groups in the Hdpa ligand. However, the smaller dihedral angle of Hdpa(N4,N6) indicated that this Hdpa possessed the p-conjugated system of the entire Hdpa ligand, similar to a coordinated bpy ligand.…”