Effect of Initial Configuration on DFT Calculations for Transition Metal Complexes

Computational methods, which solves the Schrödinger’s equation for molecules, have become an indispensable tool in last decades. And Density Functional Theory is one of the most used, and most effective computational method. Transition Metal complexes, on the other hand, have been being used extensively in many important applications in many fields, such as chemical catalysts, atomic thin films, and pharmaceutical industry. Applying computational methods to transition metal complexes has become inevitable to understand better, to control and to design these compounds. As it is known, it is very difficult to handle transition metals computationally, mostly due to near degeneracy in their electronic states. The computational algorithms usually cannot achieve as successive result as they can do for other typical elements, like carbon or nitrogen for instance. Computational methods are needed to be improved for properly deal with transition metal complexes. To find computationally cheaper but still effective methods to deal with these complexes is a major challenge. Unlike the analogue calculations, computational methods solve all equations iteratively, so there are major differences between these two calculation types. The starting point in state space (the assumed initial conformation of molecule) is could have a stronger effect then the expected, on the flow of the iterative solving algorithm of the computational approach. Here we present a comparative study for a Ruthenium complex. We have optimised the molecule several times. Each of the optimisations started from different initial molecular conformations. Then we have compared the result in different ways, like calculation times and minimum energy that had reached, to see effect of starting configurations on the calculation. It is showed that, starting configuration is an important parameter for computational calculations of transition metal complexes, and it is needed to be carefully chosen to improve success of calculations

Synthesis and reactivity of bis(diphenylphosphino)amine ligands and their application in Suzuki cross-coupling reactions

Two new bis(diphenylphosphino) amines, N,N-bis(diphenylphosphino) benzidine 1 and N, N-bis(diphenylphosphino)- 3,3-dimethoxybenzidine 2 were prepared by aminolysis. Their corresponding oxides, sulfides and selenides were readily prepared by reaction with hydrogen peroxide, elemental sulfur or grey selenium, respectively. Symmetric dinuclear palladium and platinum complexes were also isolated from the reaction with [M(cod)Cl-2] (M = Pd or Pt, cod = cycloocta-1,5-diene). All compounds were characterized by IR and NMR spectroscopy and elemental analysis and the structure of [(Ph2P)(2)N-C6H4-C6H4-N(PPh2)(2)] was determined by single crystal X-ray diffraction. The catalytic activity of palladium complexes in Suzuki coupling reactions was also investigated. (C) 2012 Elsevier B.V. All rights reserved

Catalysts for the asymmetric transfer hydrogenation of various ketones from [3-[(2S)-2-[(diphenylphosphanyl)oxy]-3-phenoxypropyl]-1-methyl-1H-imidazol-3-ium chloride] and [Ru(eta(6)-arene)(mu-Cl)Cl](2), Ir(eta(5)-C5Me5)(mu-Cl)Cl](2) or [Rh(mu-Cl)(cod)](2)

The combination of [3-[(2S)-2-[(diphenylphosphanyl)oxy]-3-phenoxypropyl]-1-methyl-1H-imidazol-3-ium chloride] with [Ru(eta(6)-arene)(mu-Cl)Cl](2), Ir(eta(5)-C5Me5)(mu-Cl)Cl](2) or [Rh(mu-Cl)(cod)](2), in the presence of KOH/isoPrOH, has been found to generate catalysts that are capable of enantioselectively reducing alkyl, aryl ketones to the corresponding (R)-alcohols. Under optimized conditions, when the catalysts were applied to the asymmetric transfer hydrogenation, we obtained the secondary alcohol products in high conversions and enantioselectivities using only 0.5 mol% catalyst loading. In addition, [3-[(2S)-2-{[(chloro(eta(4)-1,5-cyclooctadiene)rhodium)diphenyl phosphanyl] oxy}-3-phenoxypropyl]-1-methyl-1H-imidazol-3-ium chloride], (6) complex is much more active than the other analogous complexes in the transfer hydrogenation. Catalyst 6 acts as excellent catalysts, giving the corresponding (R)-1-phenyl ethanol in 99% conversion in 30 min (TOF <= 396 h(-1)) and in high enantioselectivity (92% ee)

Synthesis of ionic liquid‑based Ru(II)–phosphinite complexes and evaluation of their antioxidant, antibacterial, DNA‑binding, and DNA cleavage activities

Two Ru(II) complexes were synthesized by reaction of phosphinite-functionalized imidazolium salts [(Ph2PO)C7H11N2Cl] Cl (1) and [(Cy2PO)C7H11N2Cl]Cl (2) with 1/2 equivalent of [Ru(η6-p-cymene)(μ-Cl)Cl]2 in anhydrous CH2Cl2 and under argon atmosphere. The complexes were then isolated as analytically pure substances and characterized using multinuclear NMR and infrared spectroscopies and elemental analysis. The Ru(II) compounds were used to study their biological assay. For this purpose, radical scavenging, reducing power, antibacterial activity, DNA binding, and DNA cleavage activity were fully studied. The maximum 1,1-diphenyl-2-picrylhydrazyl radicals (DPPH) scavenging (78.9%) and reducing power were obtained from compound 4 at the concentration of 200 μg/ml. The compounds were also tested against three Gram-positive and three Gram-negative bacteria, and they were found to be more effective against Gram-positive bacteria. In addition, both compounds showed excellent DNA binding and DNA cleavage activity

Organometallic ruthenium, rhodium and iridium complexes containing a P-bound thiophene-2-(N-diphenylphosphino)methylamine ligand: Synthesis, molecular structure and catalytic activity

Reaction of Ph2PNHCH2-C4H3S with [Ru(eta(6)-p-cymene)(mu-Cl)Cl](2), [Ru(eta(6)-benzene)(mu-Cl)Cl](2), [Rh(mu-Cl)(cod)](2) and [Ir(eta(5)-C5Me5)(mu-Cl)Cl](2) yields complexes [Ru(Ph2PNHCH2-C4H3S)(eta(6)-p-cymene)Cl-2], 1, [Ru(Ph2PNHCH2-C4H3S)(eta(6)-benzene)Cl-2], 2, [Rh(Ph2PNHCH2-C4H3S)(cod)Cl], 3 and [Ir(Ph2PNHCH2-C4H3S)(eta(5)-C5Me5)Cl-2], 4, respectively. All complexes were isolated from the reaction solution and fully characterized by analytical and spectroscopic methods. The structure of [Ru(Ph2PNHCH2-C4H3S)(eta(6)-benzene)Cl-2], 2 was also determined by single crystal X-ray diffraction. 1-4 are suitable precursors forming highly active catalyst in the transfer hydrogenation of a variety of simple ketones. Notably, the catalysts obtained by using the ruthenium complexes [Ru(Ph2PNHCH2-C4H3S)(eta(6)-p-cymene)Cl-2], 1 and [Ru(Ph2PNHCH2-C4H3S)(eta(6)-benzene)Cl-2], 2 are much more active in the transfer hydrogenation converting the carbonyls to the corresponding alcohols in 98-99% yields (TOF <= 200 h(-1)) in comparison to analogous rhodium and iridium complexes

Synthesis and characterization of ether-derivatized aminophosphines and their application in C-C coupling reactions

Four new bis(phosphino)amine ligands (Ph2P)2N-C6H3-R, where R = 3,5-OMe (1), 2,5-OMe (2), 2,4-OMe (3) or 3,4-OMe (4), were prepd. via aminolysis of the corresponding dimethoxyanilines with 2 equiv. of diphenylphosphine chloride in the presence of tri-Et amine. Oxidn. of these ligands with aq. H2O2, elemental S8 or Se powder afforded the corresponding chalcogen oxides 1a-4a, sulfides 1b-4b and selenides 1c-4c in good yields. Reaction of 1-4 with [MCl2(cod)] (M = Pt, Pd; cod = cycloocta-1,5-diene) in equimolar ratios afforded cis-[MCl2{(Ph2P)2N-C6H3-R}] (M = Pt; R = 3,5-OMe 1d, R = 2,5-OMe 2d, R = 2,4-OMe 3d, and R = 3,4-OMe 4d. M = Pd; R = 3,5-OMe 1e, R = 2,5-OMe 2e, R = 2,4-OMe 3e, and R = 3,4-OMe 4e). Similarly, reaction of [Cu(CH3CN)4]PF6 with the 1-4 in 1:2 ratio gave [Cu{(Ph2P)2N-C6H3-R}2]PF6 (R = 3,5-OMe 1f, 2,5-OMe 2f, 2,4-OMe 3f and 3,4-OMe 4f). All new compds. were fully characterized by spectroscopy and elemental anal. and the mol. structures of seven representative compds. were detd. by single-crystal X-ray crystallog. In addn., the palladium complexes were investigated as pre-catalysts in C-C coupling reactions

Synthesis of new aminophosphine complexes and their catalytic activities in C-C coupling reactions

Two new aminophosphines, benzyl-N(Ph2P)(2) and 2-picolyl-N(Ph2P)(2), have been synthesized. Oxidation of the aminophosphines with either hydrogen peroxide, elemental sulfur and selenium gave the corresponding oxides, sulfides and selenides benzyl-N(Ph2P=E)(2) and 2-picolyl-N(Ph2P=E)(2), where E = O, S, or Se. Complexes [benzyl-N(Ph2P)(2)]MCl2 and [2-picolyl-N(Ph2P)(2)]MCl2, where M = Pd, Pt, were obtained by the reaction of the aminophosphines with MCl2(cod). The new compounds were characterised by NMR, IR spectroscopy and microanalysis. Furthermore, representative solid-state structures of the palladium and platinum complexes were determined using single crystal X-ray diffraction analysis. The palladium complexes were further investigated as potential catalysts in C-C coupling reactions. (c) 2008 Elsevier B. V. All rights reserved