Molecular structures of “template” (5555)macrotetracyclic chelates of 3d M(II) ions with 1,4,7,10-tetraaza-1,3,8-dodecatriene-5,6,11,12-tetrathione according to DFT quantum-chemical calculations

The geometric parameters of the molecular structures of M(II) (5555)macrotetracyclic complexes with a tetradentate (NNNN) macrocyclic ligand, formed by template reactions in the systems M(II)-ethanedithioamide-ethanedial-1,2-ethenediol systems, as well as of the molecular structure of the template ligand forming the coordination sphere of these complexes, have been calculated by the OPBE/TZVP density functional theory method. The bond lengths and bond and torsion angles in the complexes, as well as the standard enthalpies, entropies, and Gibbs energies for each of them, are reported.     

Molecular structures of (454)macrotricyclic chelates in the M(II) ion–thiosulfate anion–ethylenediamine systems according to quantum-chemical DFT calculations

The geometric parameters of the molecular structures of (454)macrotricyclic M(II) complexes with a tetradentate chelating ligand with the (NSSN)-coordination of donor sites formed by the template reactions in the M(II)–thiosulfate anion S₂O₃^2-–ethylenediamine H₂N–CH₂–CH₂–NH₂ have been calculated by the hybrid OPBE/TZVP density functional theory (DFT) method. The standard enthalpies, standard entropies, and standard Gibbs energies of formation of these complexes have been calculated, and a conclusion has been drawn that the template synthesis in these systems is possible when carrying out appropriate reactions under common conditions (in solution of solid phase).     

Molecular structures of (5656)macrotetracyclic chelates in M(II) ion–ethanedithioamide–methanimine–hydrogen cyanide quaternary systems by DFT calculations

The geometric parameters of Mn(II), Fe(II), Co(II), Ni(II), Cu(II), and Zn(II) (5656)macrotetracyclic complexes with the NNNN-coordination of the donor cites of the chelant, which can be formed upon template processes in M(II)–ethanedithioamide–methanimine–hydrogen cyanide quaternary systems, have been calculated using the density functional (DFT) hybrid method in the OPBE/TZVP approximation with the use of the Gaussian09 program package. It is shown that no one of the 5-membered chelate rings is planar, and these rings are not identical in the complexes studied. The 6-membered chelate rings are likewise not identical: one has a prominent noncoplanarity, and the other is almost planar. In all metal complexes, the nitrile nitrogen atom in one 6-membered ring noticeably departs from the plane of the ring, and in the other 6-membered ring, the respective nitrogen atom lies virtually in the plane of the ring.     

Modeling of molecular structures of (464)macrotricyclic chelates in ternary systems M(II) ion–mercaptomethanethioamide–formaldehyde

The geometric parameters of the molecular structures of (464)macrotricyclic M(II) complexes with a tetradentate chelating ligand with the (NSSN)-coordination of donor sites formed by the template reactions in the M(II)–mercaptomethanethioamide H₂N–C(=S)SH–formaldehyde CH₂O systems have been calculated by the OPBE/TZVP density functional theory (DFT) method. The bond lengths, bond angles, and some nonbonded angles in these complexes are reported. The standard enthalpies and Gibbs energies of formation of these compounds have been calculated. A conclusion has been made that the template synthesis in these systems can be realized when the corresponding reactions are carried out under traditional conditions (in solution of in the solid phase).     

Models of molecular structures of macrocyclic metal chelates in the ternary 4<Emphasis Type="Italic">d</Emphasis> M(II) ion–ethanedithioamide–ethanedial systems according to quantum-chemical DFT calculations

The thermodynamic and geometric parameters of the molecular structures of macrotricyclic Tc(II), Ru(II), Rh(II), Pd(II), Ag(II), and Cd(II) complexes with the (NSSN)-coordination of the ligand donor sites formed by complexation of the corresponding M(II) ions with ethanedithioamide H₂N–C(=S)–C(=S)–NH₂ and ethanedial HC(=O)–CH(=O) have been calculated by the OPBE/TZVPQZP hybrid density functional theory method with the use of the Gaussian09 program package. The bond lengths and bond angles in these complexes have been reported, and it has been stated that the Rh(II) and Ag(II) complexes are nearly planar, the Tc(II), Pd(II), and Cd(II) complexes are slightly nonplanar, while the Ru(II) complex exhibits a rather considerable deviation from coplanarity. The additional five-membered chelate ring resulting from template cross-linking is either strictly planar (in the Tc(II), Rh(II), Pd(II), and Ag(II) complexes) or nearly planar (in the Ru(II) and Cd(II) complexes).     

DFT quantum-chemical calculations of molecular structures for template heteroligand (5757)macrocyclic M(II) chelates of 3<Emphasis Type="Italic">d</Emphasis> elements with a 16-membered macrocyclic ligand and Br<Superscript>–</Superscript> ions

The geometric parameters of Mn(II), Fe(II), Co(II), Ni(II), Cu(II), and Zn(II) (5757)macrocyclic complexes with the NSSN-coordination of the donor sites of the chelant, which can be generated in template processes in M(II)–N-methylthiocarbohydrazide–hexanedione-2,5 systems and in the subsequent reaction of the newly formed metal chelate with 1,2-di(bromomethyl)benzene, have been calculated by the OPBE/TZVP functional density theory (DFT) hybrid method using the Gaussian09 program package. The 5-membered chelate ring is strictly planar in none of the complexes,. In all complexes (except for the Co(II) complex), 5-membered chelate rings are identical to each other. Both 7-membered chelate rings generated by the template links have a pronounced non-coplanarity. The bond angles between M–Br bonds are not 180° in any one of the complexes studied, although approaching this value.     

Geometric parameters of molecular structures of macrotricyclic chelates in MII ion—hydrazinomethane thioamide—butane-2,3-dione ternary systems (M = Co, Ni, Cu) according to the DFT B3LYP quantum chemical calculation

The geometric parameters of the macrotricyclic Co^II, Ni^II, Cu^II, and Zn^II chelates with (NSSN) coordination of the donor centers of the ligand, which are formed by complex formation between the metal ions, hydrazinomethane thioamide H₂N-HN-C(=S)-NH₂, and butane-2,3-dione Me-C(=O)-C(=O)-Me in aqueous solutions and gelatin-immobilized matrix implants, were calculated using the DFT B3LYP hybrid method in the 6-31G(d) standard basis set and the Gaussian03 program. The bond lengths, bond and torsion angles in the coordination compounds are presented. All the complexes are nearly planar.     

Quantum-chemical calculation of molecular structures of (5656)macrotetracyclic 3d-metal complexes “self-assembled” in quaternary systems M(II) ion-ethanedithioamide-formaldehyde-ammonia by the density functional theory method

The geometric parameters of (5656)macrotetracyclic complexes of Mn(II), Fe(II), Co(II), Ni(II), Cu(II), and Zn(II) with the NNNN-coordination of donor sites of the chelant formed by the template reactions in the M(II)-ethanedithioamide-formaldehyde-ammonia systems have been calculated by the OPBE/TZVP hybrid density functional theory (DFT) method with the use of the Gaussian09 program package. In all complexes, five-membered chelate rings (almost identical to each other in each complex) are nonplanar. For all M(II) ions under consideration, two additional six-membered nonplanar chelate rings formed as a result of template “cross-link” are turned at considerable angles with respect to the five-membered rings. The six-membered rings are located on different sides of the NNNN plane of the nitrogen donor atoms.     

Molecular structures of (575)macrotricyclic 3<Emphasis Type="Italic">d</Emphasis>-metal chelates in M(II)–N-methylthiocarbohydrazide–hexanedione-2,5 according to density functional theory calculations

The geometric parameters of the molecular structures and thermodynamic parameters of macrotricyclic M(II) (M = Mn, Fe, Co, Ni, Cu, Zn) complexes with an MN₂S₂ chelate core formed by the template reactions of the M(II) with N-methylthiocarbohydrazide H₃C–HN–HN–C(=S)–NH–NH₂ and hexanedione- 2,5 H₃C–C(=O)–CH₂–CH₂–C(=O)–CH₃ have been calculated by the DFT method with the Gaussian09 program package. The bond lengths, bond angles, and some nonbonded angles in these complexes have been determined. In all the complexes, the M(II) central ion is pseudotetrahedrally coordinated by the donor atoms of an inner-sphere tetradentate ligand; the (N₂S₂) group of the donor atoms is not planar. The additional seven-membered chelate rings show significant deviations from coplanarity (>60°). The noncoplanatiry of the five-membered rings is less pronounced.     

Quantum-chemical modeling of the molecular structures of (555)macrotricyclic chelates in M(II) ion–thiooxamide–glyoxal ternary systems (M = Mn,Fe, Co,Ni, Cu,Zn)

The thermodynamic and geometric parameters of isomeric macrotricyclic Mn(II), Fe(II), Co(II), Ni(II), Cu(II), and Zn(II) complexes that can form upon the complexation of the corresponding hexacyanoferrates( II) with thiooxamide H₂N–C(=S)–C(=O)–NH₂ and glyoxal HC(=O)–CH(=O) in gelatin-immobilized matrices have been calculated by the OPBE/TZVP DFT method with the use of the Gaussian09 program package. It has been found that a complex with the MN₄ chelate core is most stable for M = Mn, Fe, Co, Ni, and Zn, and the MN₂S₂ core is most stable for M = Cu. Bond lengths and bond angles have been reported, and it has been noted that in all complexes, except the Zn(II) one, the chelate core and three fivemembered chelate rings are almost planar.     

Structure of 3,3′-bis-(tribromogermyl)propionic acid according to the results of ab initio calculations

The nonempirical quantum-chemical calculations of the molecule of 3,3-bis-(tribromogermyl)-propionic acid by RHF/6-31G(d) and MP2/6-31G(d) methods were performed with full optimization of its geometry. The results of calculations by the two methods do not differ fundamentally. The calculations showed that two forms of this molecule are stable: one containing two tetrahedrally coordinated Ge atom and another with one tetrahedrally coordinated and one pentacoordinated Ge atom. The first form is typical of the crystalline state of the matter, the second is the most energy-effective for the gas. At the intramolecular interaction between the carbonyl oxygen atom and the Ge atom in the second form leading to its pentacoordination the corresponding Ge-Br bonds are polarized in such a way that the negative charges on the Br atoms and a positive charge on the Ge increase. No transfer of electron density from the oxygen to the germanium was revealed.     

Density functional theory (DFT) and ab initio investigations of the electronic and molecular structures of the monomer and the dimer of trimethylaluminium

The electronic and molecular structures of the monomer and dimer of trimethylalu-minium have been studied using density functional theory and ab initio MP2 method. The optimized geometry of the monomer Al(CH3)3 is of C3h symmetry, whereas that of the dimer [A1(CH3)3]2 contains a carbon-bridged four-membered ring structure with C2h symmetry. The hydrogen-bridged six-membered ring structure is found to be unstable. The calculated dimerization energy for the four-membered ring structure is 78 kJ/mol, in close proximity to the experimental value of 85.27 kJ/mol.     

Spectroscopic investigations (FTIR,UV-VIS,NMR) and DFT calculations on the molecular structure of Nω-Nitro-L-arginine

The spectroscopic properties of N_ω-nitro-l-arginine were investigated by FT-IR, UV-VIS, and ¹H NMR spectra. Geometrical parameters and energies were calculated using the density functional theory (DFT) B3LYP method with the 6-311G basis set. Geometrical optimization of the molecule has been performed, vibrational spectra have been calculated, and fundamental vibrations have been determined from the total energy distribution (TED) of the vibrational modes. The HOMO-LUMO analysis is carried out for various electric fields (0.0–0.025 A^?1). The HOMO-LUMO gap is decreased while increasing the electric field. The calculated quantum chemical parameters are calculated and correlated to the inhibition efficiency, A Mullliken population was also important for determining local reactivity by indicating reactive centers and identifying potential nucleophilic and electrophilic attack sites. Charge transfer occurs inside the compound based on the HOMO LUMO gap. Calculations of DFT were evaluated in their ability to predict inhibition efficiency.     

Three novel Cu(II), Cd(II) and Cr(III) complexes of 6−Methylpyridine−2−carboxylic acid with thiocyanate: Synthesis,crystal structures,DFT calculations,molecular docking and α-Glucosidase inhibition studies

Novel complexes of 6?methylpyridine?2?carboxylic acid and thiocyanate {[Cu(NCS)(6-mpa)₂], (1); [Cd(NCS)(6-mpa)]_n, (2); [Cr(NCS)(6-mpa)₂·H₂O], (3)} were synthesized, and their structures were characterized by XRD analysis, FT–IR and UV–Vis spectroscopic techniques. The inhibitory activities of the synthesized complexes (1–3) on α-glucosidase were determined by using genistein reference compound. Furthermore, the optimized geometry and vibrational harmonic frequencies for the complexes 1–3 were obtained by DFT/HSEh1PBE/6–311G(d,p)/LanL2DZ level. Electronic spectral properties were examined by using TD-DFT/HSEh1PBE/6–311G(d,p)/LanL2DZ level with CPCM model. Additionally, major contributions to the electronic transitions were determined via Swizard program. The refractive index, linear optical and non?nonlinear optical parameters of the complexes 1–3 were investigated at HSEh1PBE/6–311G(d,p) level. The docking studies of the complexes 1–3 to the binding site of the target protein (the template structure S. cerevisiae isomaltase are fulfilled. Lastly, natural bond orbital analysis was used to investigate inter- and intra-molecular bonding and interaction among bonds.     

Thermodynamic Characteristics of the Resolvation of Glycylglycinate Ions and Their Contribution to the Change in Stability of Complexes with Cu(II) and Ni(II) in Aqueous–Organic Solvents

Russian Journal of Physical Chemistry A - Thermodynamic characteristics (∆G, ∆Н, T∆S) of the resolvation of glycylglycine and its protonated and deprotonated forms in...     

Metal chelates of Triazine-Schiff-bases: Complex formation of 3-(α-phenyl)ethylidenehydrazino-5,6-diphenyl-1,2,4-triazine with copper(II)

Summary Complex formation of copper(II)-ions with 3-(-Phenyl)ethylidenehydrazino-5,6-diphenyl-1,2,4-triazine (BHT) has been investigated using UV-VIS-, IR-, and electrochemical methods. Optimal pH for the 1:1 complex formation (and therefore for analytical applications) was found at 5.4. This complex could be isolated. The acid dissociation constant of the free ligand ispK _a=13.60; formation constants for 1:1 and 1:2 complexes were found to be logK ₁=12.0 and logK ₂=10.4, respectively. Polarographic reduction of both the free ligand and the Cu(II)-complexes is irreversible, diffusion controlled and like the stability of the complexpH-dependent.In course of absence of the Faculty of Education, Ain Schams University, Roxy, Cairo, Egypt.     

Substituted derivatives of tris(butadiene)-molybdenum and -tungsten; the molecular structures of (CH2CMeCMeCH2)3M (M = Mo,W)

Tris(substituted butadiene) complexes of molybdenum and tungsten have been prepared by the reduction of the metal halides with anthracene-activated magnesium in the presence of the appropriate diene. An X-ray diffraction study has shown tris(2,3-dimethylbutadiene)molybdenum and its tungsten analogue to be isomorphous, with each diene unit displaying a long—short—long bond alternation, and having short metal to terminal carbon atom distances, in marked contrast to the unsubstituted complexes.     

Ruthenium(II) complexes of azoimine and α-diimine ligands: synthesis,spectroscopic and electrochemical properties,crystal structures and DFT calculations

Five octahedral ruthenium(II) complexes with azoimine–quinoline (Azo) and α-diimine (L) ligands having the general formula [Ru^II(L)(Azo)Cl](PF₆) (1–5) {Azo: PhN=NC(COMe)=NC₉H₆N, L = 4,4′-dimethoxy-2,2′-bipyridine (dmeb) (1), 4,4′-di-tertbutyl-2,2′-bipyridine (dtb) (2), 1,10-phenanthroline (phen) (3), 5-chlorophenanthroline (Clphen) (4), or 3,4,7,8-tetramethyl-1,10-phenanthroline (tmphen) (5)} were prepared by stepwise addition of the tridentate azoimine (H₂Azo) and α-diimine (L) pro-ligands to RuCl₃ in refluxing EtOH. The tridentate azoimine–quinoline ligands coordinate to ruthenium via the Azo-N′, N′-imine and N″-quinolone nitrogen atoms. The spectroscopic properties (IR, UV/Vis, ¹H, ¹³C and ¹⁹F NMR) and electrochemical behavior of complexes 1–5 and the X-ray crystal structures of complexes 2 and 3 are presented. The coordination of Ru(II) to these strong π-acceptor ligands (Azo and L) results in a large anodic shift for the Ru(III/II) couples of 1.63–1.72 V versus NHE. The electronic spectra in MeCN and IR spectra in CH₂Cl₂ for complex 3 in its oxidized 3 ⁺ and reduced 3 ^? forms were investigated. The calculated absorption spectrum of 3 in MeCN was used to assign the UV–Vis absorption bands.     

Influence of intermolecular interactions on the Mössbauer quadrupole splitting of organotin(IV) compounds as studied by DFT calculations

The influence of intermolecular interactions on the M?ssbauer quadrupole splitting (Delta) of 119Sn was investigated in detail by density functional theory (DFT) calculations. Six organotin(IV) complexes [Me2Sn(acac)2 (1), Ph3SnCl (2), Me3Sn-succinimide (3), Me3Sn-phthalimide (4), Me3SnCl (5), and cHex3SnCl (6)] of known solid-state structures and quadrupole splittings were selected. Theoretical Delta values were calculated for both fully optimized geometries and experimental solid-state structures of different size, and the results were compared to the experimental Delta values. Compared to a synthetic procedure described in the literature for compound 4, a more convenient synthesis is reported here. The experimental Delta of this compound has also been redetermined at 80 K. For compounds with negligible intermolecular interactions in the solid state, calculated Delta values obtained did not vary significantly. In contrast, the calculated Delta values turned out to be very sensitive to the size of the supramolecular moiety considered in the crystal lattice. The crystal structure of compound 2 shows no significant intermolecular interactions; however, the calculated and the experimental Delta values remained very different, even when the supramolecular moiety considered was extended. Distortion of the coordination sphere of tin in the molecule of 2 toward a trigonal bipyramidal geometry was considered, and a possible weak intermolecular Sn...Cl interaction was included in the model. Steps of the distortion followed the new structure correlation function, which was found for the R3SnCl (R=alkyl, aryl) compounds. The experimental Delta value could be approached by this method. These results suggest that compound 2 is involved in some unexpected intermolecular interaction at 80 K.     

Temperature-dependent synthesis, crystal structures, characterizations, and DFT calculations of two new copper(II) complexes with p-fluorobenzoic acid and 2,2′-bipyridine ligands

Two new copper(II) complexes, [Cu(p-FBA)₂(2,2′-bpy)]·(H₂O) (1) and [Cu(p-FBA)(2,2′-bpy)₂]·(p-FBA)₂ (2) {p-FBA = p-fluorobenzoic acid, 2,2′-bpy = 2,2′-bipyridine} have been obtained from an identical starting mixture using temperature as the only independent variable and characterized by X-ray single crystal diffraction as well as with infrared spectroscopy, elemental analysis, and thermogravimetric analysis. The results reveal that 1 has 1D infinite chain structure formed by O–H···O hydrogen bonds, while 2 features a 0D structure. Additionally, there exist C–H···O hydrogen bonds and π–π stacking interactions in 1, forming 2D supramolecular structure. Furthermore, density functional theory (DFT) calculations of the structures, stabilities, orbital energies, composition characteristics of some frontier molecular orbitals and Mulliken charge distributions of the [Cu(p-FBA)₂(2,2′-bpy)] of 1 and [Cu(p-FBA)(2,2′-bpy)₂]⁺ cation of 2 were performed by means of Gaussian 03W package and taking B3LYP/lanl2dz basis set.