cis–trans Isomerism in mixed-ligand ruthenium(II) complexes containing bis(phosphine) and azoimine ligands
作者:Mousa Al-Noaimi、Mahmoud Sunjuk、Mohammad El-khateeb、Salim F. Haddad、Alaa Haniyeh、Murad AlDamen
DOI:10.1016/j.poly.2012.04.044
日期:2012.7
This study presents the syntheses and characterization of mixed-ligand azoimine-diphosphine ruthenium complexes of the general formula [RuCl2(Azo)(P-P)] (C1-C5) (Azo = C6H5N=NC(COCH3)=NC6H5; P-P = 1,2-bis(dimethylphosphino)ethane (dmpe) (C1), cis-1,2-bis(diphenylphosphino)ethylene (depe) (C2), 1.1'-bis(diphenylphosphino)methane (dppm) (C3), 1,2-bis(diphenylphosphino)benzene (dbpe) (C4),1, 2-bis(di(pentaflurophenyl)phosphino)ethane (F-dppe) (C5)). These complexes were synthesized via the reaction of RuCl3, azoimine and the diphosphine ligands in ethanol solutions. The X-ray structure of C2 reveals a cis-dichloro geometry, in spite of the bulky P-P ligand, and this is attributed to the presence of an intramolecular pi-pi interaction between benzene rings (on the Azo and P-P ligands) [centroid-centroid distances = 3.596 and 3.654 angstrom; dihedral angle between ring planes = 13.2(3) and 15.4(4)degrees for the two independent molecules]. In contrast, the X-ray structure of C1, with a less bulky dmpe ligand in which no Ph rings are available for pi-pi bonding, revealed a trans-dichloro geometry. In addition to the X-ray structures of Cl and C2, this work presents and discusses the spectroscopic (IR, UV-Vis, H-1 NMR and P-31 NMR) and electrochemical (cyclic voltammetry) behavior of C1-C5. (c) 2012 Elsevier Ltd. All rights reserved.