An-Najah Staff

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 p-1 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.

In the present work, a theoretical study of two quinoxaline-type organic compounds, (2Z)-2-[(3E)-3(2-oxo-2-phenylethylidene)-3, 4-dihydroquinoxalin-2(1H)-ylidene]-1 phenylethanone (Q5) and (Z)-2((E)-3-(2-oxo-2-phenylethylidene)-3, 4-dihydroquinoxalin-2(1H)-ylidene)-1-phenylethanone (Q6), has been performed using density functional theory (DFT) at the B3LYP/6-31G(d) level in order to elucidate the different inhibition efficiencies and reactive sites of these compounds as corrosion inhibitors. The efficiencies of corrosion inhibitors and the global chemical reactivity relate to some parameters, such as highest occupied molecular orbital energy (E ), lowest unoccupied molecular orbital energy (E LUMO HOMO ), energy gap (ΔE), dipole moment (µ), electronegativity (χ), electron affinity (A), global hardness (η), softness (s), ionization potential (I), the fraction of electrons transferred (∆N), the global electrophilicity (ω) and the total energy (TE), were calculated. All calculation has been performed by considering Density Functional Theory (DFT) using the GAUSSIAN03W suite of programs. The calculated results are in agreement with the experimental data on the whole.