Synthesis, characterization, and molecular structure of Ru(II) complex containing 2,5-pyridinedicarboxylic acid

This article presents a combined experimental and computational study of Ru(II) complex containing 2,5- pyridinedicarboxylic acid ligand. The novel complex [Ru(py-2,5-COOH)2(PPh3)2] 3H2O has been obtained in the reaction of [RuCl2(PPh3)3] with 2,5-pyridinedicarboxylic acid in methanol and has been studied by IR, 1H, 31P NMR, UV–Vis spectroscopy, and X-ray crystallography. The electronic structure of [Ru(py-2,5-COOH)2(PPh3)2] has been calculated with the density functional theory (DFT) method. The spin-allowed electronic transitions of the complex have been calculated with the time-dependent DFT method, and the UV–Vis spectrum has been discussed on this basis and rationalized by determination of ligand field splitting (10Dq) and Racah’s parameters from the experimental spectrum. The luminescence property of the complex has been examined

A ruthenium(II) hydride carbonyl complex with 4-phenylpyrimidine as co-ligand

The reaction of [RuHCl(CO)(PPh3)3] with 4-phenylpyrimidine gave a new ruthenium(II) complex, namely [RuHCl(CO)(PPh3)2(pyrim-4-Ph)]. The complex has been studied by IR and UV–vis spectroscopy and by X-ray crystallography. The molecular orbitals of the complex have been calculated by density functional theory. The spin-allowed singlet–singlet electronic transitions of the complex have been calculated by time-dependent DFT, and the UV–vis spectrum of the compound has been discussed on this basis. The emission properties of the complex were also studied

Spectroscopic characterization of chloride and pseudohalide ruthenium (II) complexes with 4-(4-nitrobenzyl) pyridine

Chloride, isocyanate and isothiocyanate hydride carbonyl ruthenium(II) complexes of 4-(4-nitrobenzyl)pyridine were synthesized from the precursor complex [RuHCl(CO)(PPh3)3] and characterized by IR, NMR, UV-Vis spectroscopy and X-ray crystallography. The electronic structures of the complexes were investigated by means of DFT calculations, based on their crystal structures. The spin-allowed singlet-singlet electronic transitions of the complexes were calculated by time-dependent DFT, and the UV-Vis spectra are discussed on this basis. The emission properties of the complexes were studied at ambient temperature, and the quantum yields of fluorescence, the lifetimes and nature of the excited states are discussed. The chloride and isothiocyanate complexes are practically nonemissive, with quantum yields under 0.01 %. Interpretation of spectra, supported by TD-DFT calculations, indicates that in this energy region, the transitions have MLCT character with admixture of LLCT (chloride and isothiocyanate complexes). The dominant LLCT character was visible in the case of the most emissive (isocyanate) complex. The low values of the lifetimes and quantum yields for these complexes indicate the influence of the metal center in the emission process

Spectroscopic, structure and DFT studies of palladium(II) complexes with pyridine-type ligands

Five palladium(II) complexes with pyridine derivative ligands have been synthesized. The molecular structures of the complexes were determined by X-ray crystallography, and their spectroscopic properties were studied. Based on the crystal structures, computational investigations were carried out in order to determine the electronic structures of the complexes. The electronic spectra 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. The emission properties of the complexes have been examined

Chloride and pseudohalide hydride-carbonyl ruthenium(II) complexes with 4-pyrrolidinopyridine as co-ligand

Chloride and pseudohalide (N3 -, NCS-) hydride-carbonyl ruthenium(II) complexes with 4-pyrrolidinopyridine as co-ligand were synthesized and characterized by IR, 1H, and 31P NMR, electronic absorption and emission spectroscopy and X-ray crystallography. The electronic structures of the complexes were calculated by density functional theory (DFT) on their crystal structures. The spin-allowed singlet–singlet electronic transitions of the complexes were calculated by time-dependent DFT, and the UV–Vis spectra have been discussed on these basis. The emission properties of the complexes were also studied

X-ray studies, spectroscopic characterisation and DFT calculations for Mn(II), Ni(II) and Cu(II) complexes with 5,6-diphenyl-3-(2-pyridyl)-1,2,4-triazine

New complexes with formula [M(SCN)2(L)2] where M = Mn(II), Cu(II) were synthesized in simple reactions of metal chlorides with ammonia thiocyanate and 5,6-diphenyl-3-(2-pyridyl)-1,2,4-triazine (pytz) ligand in methanol solutions. In the reaction of NiCl2 6H2O and pytz ligand the [NiCl2(pytz)2] 2CH3OH complex was obtained. The complexes were studied by IR, UV–vis, EPR spectroscopy and X-ray crystallography. Electronic structures of the complexes were calculated using DFT method, and apart from the descriptions of frontier molecular orbitals and the relocation of the electron density of the compounds, the bonding properties in the complexes were determined

Molecular, spectroscopic, and magnetic properties of cobalt(II) complexes with heteroaromatic N(O)-donor ligands

New [Co(SCN)2(L)4/2] complexes, where L = b-pic (1), pyCH2OH (2), py(CH2)3OH (3), 1,2,4- triazolo[1,5-a]pyrimidine (4), [CoCl2(urotrop)2] (5), and [Co(DMIM)3]Cl2 H2O (6) where urotrop = hexamethylenetetramine and DMIM = 2,20-bis(4,5-dimethylimidazolyl) were synthesized in simple reactions of CoCl2 6H2O with ammonia thiocyanate and pyridine type ligands or urotropine and diimidazolyl ligands with cobalt(II) chloride in methanol solutions. The orthorhombic crystallization for (1), (2), and (4), the monoclinic one for (3) and (5) as well as the hexagonal one for (6) were found. The plots of the overlap population density-of-states indicated nonbonding character of the interactions between pyridine derivatives ligands and cobalt(II) ions in the complexes (1)–(4). The electronic spectra showed almost perfect octahedral complex in the case of (6). The magnetic susceptibility measurements revealed paramagnetic behavior with low values of the Curie–Weiss temperature, positive for complex (5) and negative for the other ones, although the transition to collective magnetic state at low temperatures for (4) and (5) was evidenced by an observation of antiferromagnetic coupling with Ne´el temperature of 4.5 K and the ferromagnetic one with Curie temperature of 10 K, respectively

Metal-Free Mild Synthesis of Novel 1′H-Spiro[Cycloalkyl-1,2′- quinazolin]-4′(3′H)-ones by an Organocatalytic Cascade Reaction

A concise organocatalytic method for the facile synthesis of some novel 1′H-spirocycloalkyl-1,2′-quinazolin]-4′(3′H)-ones via a one-pot, three-component condensation of isatoic anhydride, aryl or aliphatic amines and a cyclic ketone is described

A copper(I) phosphine complex with 5,7-dinitro-2-methylquinolin-8-ol as co-ligand

5,7-Dinitro-2-methylquinolin-8-ol has been synthesized, and its copper(I) complex has been prepared. Both the free 2-MequinNO2 ligand and its complex were characterized by IR, NMR, and UV–Vis spectra. The structure of the [Cu(2-MequinNO2)(PPh3)2] complex has been determined by single-crystal X-ray analysis. The free 2-MequinNO2 ligand reveals luminescence in contrast to the complex. For 2-MequinNO2, the quantum yield, lifetime of the excited state, and the rate constants of both radiative and non-radiative decay have been determined. The lack of luminescence for the complex has been explained with the use of a quantum chemical study

Ruthenium(II) 8-quinolinolates: Synthesis, characterization, crystal structure and catalysis in the synthesis of 2-oxazolines

New octahedral ruthenium(II) complexes (1e4) have been synthesized from the reaction of ruthenium(II) precursors [RuHCl(CO)(EPh3)3] (E ¼ P or As) with the bidentate Schiff base ligands, 2-((2,6-dimethylphenylimino)methyl)quinolin-8-ol (L1) and 2-((2,6-diisopropylphenylimino)methyl)quinolin-8-ol (L2) in ethanol. These complexes have been characterized by elemental analyses, IR, UVeVis, 1H, 13C and 31P NMR and ESI-Mass spectroscopy. The molecular structure of the complex [RuCl(CO)(PPh3)2(L2)] (2) was determined by single-crystal X-ray diffraction, which reveals a distorted octahedral geometry around ruthenium(II) ion. The catalytic activity of the new complexes was evaluated for the condensation of nitriles with ethanolamine under solvent free conditions. The processes were operative with aromatic and heteroaromatic nitriles and tolerated several substitutional groups. The studies on the effect of substitution over ligands, coligands, reaction time, temperature and catalyst loading were carried out in order to find the best catalyst in this series of complexes and favorable reaction conditions. A probable mechanism for the catalytic condensation of nitrile has also been proposed. The catalyst was recovered and recycled up to five times without significant loss of its activity