Showing papers on "Tetrahedral molecular geometry published in 2011"
TL;DR: Two mononuclear high-spin Fe(II) complexes with trigonal planar and distorted tetrahedral geometries reveal the profound effect of out-of-state spin-orbit coupling (SOC) on slow magnetic relaxation.
Abstract: Two mononuclear high-spin FeII complexes with trigonal planar ([FeII(N(TMS)2)2(PCy3)] (1) and distorted tetrahedral ([FeII(N(TMS)2)2(depe)] (2) geometries are reported (TMS = SiMe3, Cy = cyclohexyl, depe = 1,2-bis(diethylphosphino)ethane). The magnetic properties of 1 and 2 reveal the profound effect of out-of-state spin–orbit coupling (SOC) on slow magnetic relaxation. Complex 1 exhibits slow relaxation of the magnetization under an applied optimal dc field of 600 Oe due to the presence of low-lying electronic excited states that mix with the ground electronic state. This mixing re-introduces orbital angular momentum into the electronic ground state via SOC, and 1 thus behaves as a field-induced single-molecule magnet. In complex 2, the lowest-energy excited states have higher energy due to the ligand field of the distorted tetrahedral geometry. This higher energy gap minimizes out-of-state SOC mixing and zero-field splitting, thus precluding slow relaxation of the magnetization for 2.
188 citations
TL;DR: The combination of 2 (0.005 mmol) with hydrogen peroxide in acetonitrile is found to be an active catalyst for the oxidation of primary and secondary alcohols to their corresponding acids and ketones, respectively, at room temperature.
Abstract: New four-coordinated tetrahedral copper(I) complexes have been synthesized from the reactions between [CuCl2(PPh3)2] and N-(diphenylcarbamothioyl)benzamide (HL1) or N-(diethylcarbamothioyl)benzamide (HL2) in benzene. These complexes have been characterized by elemental analyses, IR, UV/Vis, 1H, 13C and 31P NMR spectroscopy. The molecular structure of both the complexes, [CuCl(HL1)2(PPh3)] (1) and [CuCl(HL2)(PPh3)2] (2) were determined by single-crystal X-ray diffraction, which reveals distorted tetrahedral geometry around each Cu(I) ion. The combination of 2 (0.005 mmol) with hydrogen peroxide (2.5 mmol) in acetonitrile is found to be an active catalyst for the oxidation of primary and secondary alcohols (0.5 mmol) to their corresponding acids and ketones, respectively, at room temperature.
65 citations
TL;DR: The reversible solid-state structural transformation between crystalline 1 with 1D ladderlike framework and its dehydrated powder 2, [Zn(HBTC)(BPE)0.5]n, with 2D framework via the displacement of coordinated water molecule to HBTC(2-) ligand, by thermal de/rehydrated processes has been verified by PXRD measurements.
Abstract: A new coordination polymer, [Zn(HBTC)(BPE)0.5(H2O)]n·nH2O (1) with an extended 1D ladderlike metal−organic framework (MOF) has been synthesized and structural characterized by single-crystal X-ray diffraction method. Structural determination reveals that, in compound 1, the Zn(II) ion is four-coordinated in a distorted tetrahedral geometry, bonded to one nitrogen atom from one BPE ligand, and three oxygen atoms from two monodentate carboxylate groups of two HBTC2− ligands and one coordinated water molecule. The HBTC2− acts as a bridging ligand with a bis-monodentate coordination mode, connecting the Zn(II) ions to form a one-dimensional (1D) [Zn(HBTC)] chain. Two 1D chains are then interlinked via the connectivity between the ZnII ions and anti-BPE liagnds to complete the 1D ladderlike MOF. Adjacent 1D Ladders are further extended to a 2D hydrogen-bonded layered network through the intermolecular O−H···O hydrogen bond between the carboxylic group and carboxylate group of interladder HBTC2− ligand. Adjacen...
45 citations
TL;DR: The deprotonated ligand acts as a dibasic tridentate (ONS) via phenolate oxygen, azomethine (CN), and thiolate (C-S) groups and molecular parameters of the ligand and its metal complexes have been calculated and correlated with the experimental data such as IR and TGA results.
32 citations
TL;DR: In this article, the reactions of the two common dyes [2TMPACT and 4PENI] with Mn(II, Co(II), Ni(II) and Cu(II)] ions were done.
27 citations
TL;DR: In this paper, DFT computations have been performed in acetone and water solvents in order to investigate the mechanism of hydrolysis of acid chlorides, and the structure of the transition state (TS) has distorted tetrahedral geometry.
25 citations
24 citations
TL;DR: In this paper, a single crystal X-ray structure of [Cu(SRaaiNR′)(PPh3)I] (SEtaaiNH = 2-[(o-thioethyl)phenylazo]imidazole) shows a distorted tetrahedral geometry of the copper center with bidentate, N(azo), N(imidaze) chelation of SEtaai NH and coordination from PPh3 and iodine.
23 citations
TL;DR: In this paper, a series of metal(II) complexes were synthesized from azo Schiff base ligand (N′E)-N′-(5-((4-chlorophenyl)diazenyl)-2-hydroxybenzylidene)-2 -hydroxylbenzohydrazide and characterized on the basis of elemental analyses, electronic, IR, and 1H NMR spectra, magnetic susceptibility and also by aid of scanning electron microscopy (SEM), X-ray powder diffraction, fluorescence spectral studies, and molar
Abstract: A series of metal(II) complexes ML where M = VO(II), Co(II), Ni(II), Cu(II), and Zn(II) have been synthesized from azo Schiff base ligand (N′E)-N′-(5-((4-chlorophenyl)diazenyl)-2-hydroxybenzylidene)-2-hydroxybenzohydrazide and characterized on the basis of elemental analyses, electronic, IR, and 1H NMR spectra, magnetic susceptibility and also by aid of scanning electron microscopy (SEM), X-ray powder diffraction, fluorescence spectral studies, and molar conductivity measurements. Conductivity measurements reveal that the complexes are nonelectrolytes. Spectroscopy and other analytical studies reveal distorted square planar geometry for copper, square-pyramidal geometry for oxovanadium, and tetrahedral geometry for other complexes. Redox behavior of the copper(II) complex has been studied with cyclic voltammetry, and the biological activities of the ligand and metal complexes have been studied against several microorganisms by the well diffusion method. All synthesized compounds can serve as potential photoactive materials as indicated from their characteristic fluorescence properties. The second harmonic generation (SHG) efficiency of the ligand was measured and found to be higher than that of urea and KDP. The SEM image of the copper(II) complex implies that the size of the particles is 50 nm.
23 citations
TL;DR: In this paper, a binuclear copper complex with a distorted tetrahedral geometry was synthesized from the reaction of Cu(NO3)2·3H2O and CuCl2·2H 2O with their corresponding 2-pyridylphosphine ligands.
22 citations
TL;DR: Two new cadmium coordination polymers, namely Cd(HAmTrz-COO)(4)(NH4+)(2)] 1; and Cd (2)I-2]-n) 2, have been prepared based on HAmtrz-CoOH as ligand, and their crystal structures were determined by single-crystal X-ray diffraction technique as mentioned in this paper.
TL;DR: In this article, a template condensation of quinoxaline-2-carboxaldehyde, L-histidine, and metal compound was used to synthesize Schiff base complexes.
Abstract: New Schiff base complexes of Mn(II), Fe(III), Co(II), Ni(II), Cu(II), and Zn(II) were synthesized by template condensation of quinoxaline-2-carboxaldehyde, L-histidine, and the metal compound, and were characterized by elemental analysis, fourier transform infrared spectroscopy, electronic spectra, conductance measurements, magnetic susceptibility measurements, ESR spectra, and thermal analysis. In all the complexes, the Schiff base coordinates through azomethine nitrogen, quinoxaline nitrogen, and carboxylato oxygen. The physicochemical and spectroscopic measurements reveal square planar geometry for the copper(II) complex, tetrahedral geometry for the manganese(II), cobalt(II), and zinc(II) complexes, and octahedral geometry for the iron(III) and nickel(II) complexes.
TL;DR: In the present work, the calculations have been conducted on particle configurations resulting from reverse Monte Carlo computer modeling: these particle arrangements have the advantage that they are fully consistent with structure factors from neutron and x-ray diffraction measurements.
Abstract: Analyses of the intermolecular structure of molecular liquids containing slightly distorted tetrahedral molecules of the CXY(3)-type are described. The process is composed of the determination of several different distance-dependent orientational correlation functions, including ones that are introduced here. As a result, a complete structure classification could be provided for CXY(3) molecular liquids, namely for liquid chloroform, bromoform, and methyl-iodide. In the present work, the calculations have been conducted on particle configurations resulting from reverse Monte Carlo computer modeling: these particle arrangements have the advantage that they are fully consistent with structure factors from neutron and x-ray diffraction measurements. It has been established that as the separation between neighboring molecules increases, the dominant mutual orientations change from face-to-face to edge-to-edge, via the edge-to-face arrangements. Depending on the actual liquid, these geometrical elements (edges and faces of the distorted tetrahedra) were found to contain different atoms. From the set of liquids studied here, the structure of methyl-iodide was found to be easiest to describe on the basis of pure steric effects (molecular shape, size, and density) and the structure of liquid chloroform seems to be the furthest away from the corresponding "flexible fused hard spheres" like reference system.
TL;DR: The mixed ligand dithiocarbamate complex was synthesized by the reaction between the ammonium salt of the DBS ligands with mercury salt as mentioned in this paper, which was shown to have a distorted tetrahedral geometry for each mercury atom defined by four sulphur atoms derived from two asymmetrically chelating DBSs.
Abstract: The mixed ligand dithiocarbamate complex was synthesized by the reaction between the ammonium salt of the dithiocarbamate ligands with mercury salt. There are two mercury complexes in the asymmetric unit with a compositional disorder between an ethyl group and a methyl group. A distorted tetrahedral geometry is found for each mercury atom defined by four sulphur atoms derived from two asymmetrically chelating dithiocarbamate ligands. IR spectra show thioureide υ(C–N) bands at 1491 cm−1 which is higher than observed in the simple complexes of the same ligands. The effect of alkyl substituents were observed in the magnetic unequivalence of the thioureide and phenyl units in the NMR spectroscopy. The molecules are related to each other by virtue of the compositional disorder which exists at three positions in the alkyl group across the unit. The compound crystallizes in the triclinic space group P-1 with a = 10.4764(10) A, b = 11.0433(10) A, c = 18.5566(17) A, α = 97.8980(10)°, β = 95.3340(10)°, γ = 110.3010(10)°, and Z = 2. In the molecular structure, there are two tetrahedrally coordinated mercury complexes in the asymmetric unit with compositional disorder at the positions of C17, C26, and C35 between an ethyl group and a methyl group. The molecules are related to each other by virtue of the compositional disorder.
TL;DR: In this paper, the synthesis, characterization, and mesomorphic properties of a new series of Schiff bases 2a-h and metal complexes 1a- h-M are prepared and their mesomorph properties studied.
TL;DR: In this paper, two novel silver(I) complexes, namely [Ag2(μ3-sac)2 (μ-nmpen)]n (1) and [Ag(sac)(mpr)]2 (2) have been synthesized and characterized by IR spectra, thermal analysis and single crystal X-ray diffraction techniques.
TL;DR: In this article, the ortho-tert-butyl substituents were found to be oriented in the same direction as the Ge-X bond in each molecule, which results in distortions in 1-4 from the ideal tetrahedral geometry.
TL;DR: As anticipated, the weakly coordinating nitromethane ligands in 1 are easily displaced by a variety of donors, including Et(2)O, MeCN, and piperidine, and more surprisingly, the addition of mesitylene to 1 results in the formation of an η(6)-coordinated nickel arene complex, suggesting a relatively weak Ni-arene interaction.
Abstract: The reaction of [NO][PF6] with excess Ni powder in CH3NO2, in the presence of 2 mol % NiI2, results in the formation of [Ni(NO)(CH3NO2)3][PF6] (1), which can be isolated in modest yield as a blue crystalline solid. Also formed in the reaction is [Ni(CH3NO2)6][PF6]2 (2), which can be isolated in comparable yield as a pale-green solid. In the solid state, 1 exhibits tetrahedral geometry about the Ni center with a linear nitrosyl ligand [Ni1–N1–O1 = 174.1(8)°] and a short Ni–N bond distance [1.626(6) A]. As anticipated, the weakly coordinating nitromethane ligands in 1 are easily displaced by a variety of donors, including Et2O, MeCN, and piperidine (NC5H11). More surprisingly, the addition of mesitylene to 1 results in the formation of an η6-coordinated nickel arene complex, [Ni(η6-1,3,5-Me3C6H3)(NO)][PF6] (6). In the solid state, complex 6 exhibits a long Ni–Ccent distance [1.682(2) A], suggesting a relatively weak Ni–arene interaction, a consequence of the strong π-back-donation to the nitrosyl ligand. Th...
TL;DR: The simulations indicate that water preferentially associates with borohydride on the tetrahedral corners and edges, causing transitions to excited states with p character to become more intense and a sharp feature, uncharacteristic of tetrahed molecules, to emerge.
Abstract: Borohydride salts have been considered as good prospects for transportable hydrogen storage materials, with molecular hydrogen released via hydrolysis. We examine details of the hydration of sodium borohydride by the combination of X-ray absorption spectroscopy and first principles' theory. Compared to solid sodium borohydride, the aqueous sample exhibits an uncharacteristically narrow absorption feature that is shifted to lower energy, and ascribed to the formation of dihydrogen bonds between borohydride and water that weaken the boron–hydrogen covalent bonds. Water also acts to localize the highly excited molecular orbitals of borohydride, causing transitions to excited states with p character to become more intense and a sharp feature, uncharacteristic of tetrahedral molecules, to emerge. The simulations indicate that water preferentially associates with borohydride on the tetrahedral corners and edges.
TL;DR: The reaction of Zn(κ2O,O′−OAc)2·2H2O with two equiv of 3,5-lutidine in methanol at room temperature for 12-h afforded [Zn(OAc,O 2CAr)2(3,5 lutidine)2]· H2O (1) in 91% yield.
TL;DR: In this paper, seven 2amino-5-substituted-aryl-1,3,4-oxadiazole Schiff bases have been synthesized and characterized by various physico-chemical studies, including elemental analyses, infrared, 1H NMR, UV-Vis, and mass spectral studies as well as thermal decomposition.
Abstract: Sn(II)-complexes of seven 2-amino-5-substituted-aryl-1,3,4-oxadiazole Schiff bases have been synthesized and characterized by various physico-chemical studies. Their structures have been confirmed by elemental analyses, infrared, 1H NMR, UV-Vis, and mass spectral studies as well as thermal decomposition. Conductance measurements in methanol show these complexes to be non-electrolytes, and the molecular weight determinations support the proposed molecular formulae. The molecular structures of the complexes have been optimized by CS Chem 3-D Ultra Molecular Modeling and Analysis Program showing tetrahedral geometry. The bio-efficacy of the complexes has been examined against the growth of bacteria (Escherichia coli and Staphylococcus aureus) and fungi (Aspergillus flavus and Candida albicans) in vitro to evaluate their anti-microbial potential.
TL;DR: In this paper, a polymeric heterothiometallic complex is characterized by X-ray crystallography, which is called WS4Cu2(μ-bbd)n (4).
TL;DR: In this paper, a 4-coordinate square planar/tetrahedral geometry for the Ni(II), Cu(II, and Zn(II) complexes of the Schiff base 3-(-1-(4,6-dimethyl-2-pyrimidinylimino)methyl-2naphthol have been synthesized and characterized by infrared (IR), electronic, nuclear magnetic resonance (1H-NMR), and mass spectroscopies, elemental and thermal analyses, and room-temperature magnetic, powder x-ray diffraction,
Abstract: Mn(II), Co(II), Ni(II), Cu(II), and Zn(II) complexes of the Schiff base 3-(-1-(4,6-dimethyl-2-pyrimidinylimino)methyl-2-naphthol have been synthesized and characterized by infrared (IR), electronic, nuclear magnetic resonance (1H-NMR), and mass spectroscopies, elemental and thermal analyses, and room-temperature magnetic, powder x-ray diffraction, and conductance measurements. The involvement of the azomethine N and enol O atoms in bonding resulted in an N2O2 chromophore around the central metal atom. The room-temperature magnetic data, IR, and electronic spectral measurements are corroborative of a 4-coordinate square planar/tetrahedral geometry for the Ni(II), Cu(II), and Zn(II) complexes, and a 6-coordinate octahedral geometry for the Mn(II) and Co(II) complexes with water occupying the fifth and sixth coordination sites. All the complexes are high spin and nonelectrolyte in dimethylformamide (DMF). The metal complexes generally have mild to very good anticancer activity in vitro against HL 60 (leukemi...
TL;DR: In this paper, a tetranuclear complex was synthesized from the self-assembly of copper(II) perchlorate and the tridentate Schiff base ligand (2E,3E)-3-(2-aminopropylimino) butan-2-one oxime (HL).
TL;DR: In this article, three mercury(II) complexes, [Hg((23-MeO-ba) 2 en)X 2 ] (X = I ( 1 ), Br ( 2 ) and Cl( 3 )), and the Schiff base ligand (23-meO-baba 2 en ) 2 en were synthesized and characterized by elemental analyses, FT-IR and 1 H NMR spectroscopy.
TL;DR: A series of LZn(II)Br (1,4) and LCd(II), Cl complexes (9,11) has been prepared by the reaction of metal halide precursors with the lithium salts of the N2S− ligands as mentioned in this paper.
TL;DR: In this paper, a 4-coordinate tetrahedral geometry for Mn, Co, Ni, Cu, Zn, Pd, and Zn(II) complexes was shown for 4-thiophen-3-yl)-aniline.
Abstract: 4-(Thiophen-3-yl)-aniline undergoes condensation with o-vanillin to form an ONS donor Schiff base, 2-methoxy-6-[(4-thiophene-3-yl-phenylimino)-methyl]-phenol, which forms complexes of the type [ML2]H2O (where M = Mn, Co, Ni, Cu, Zn, Pd). These complexes are characterized by elemental analysis, 1H nmr, electronic, mass, and IR spectroscopies and conductance measurements. The electronic, IR and CHN data are supportive of a 4-coordinate tetrahedral geometry for Mn(II), Co(II), Ni(II), and Zn(II) complexes and square-planar geometry for Cu(II) and Pd(II) complexes, with the chromophores N2O2. The magnetic data reveals that the complexes are magnetically dilute and mononuclear with exception of the Cu(II) complex, which exhibits some anti-ferromagnetisms. The complexes are air-stable solids, and none is an electrolyte in nitro methane.
TL;DR: A new four-coordinate cobalt(II) complex with 1,3-bis(1-ethylbenzimidazol-2-yl)-2-oxopropane (Etobb), Co(Et Cobb)Cl2, has been synthesized and characterized by elemental analysis, electrical conductivities, infrared, and UV-Vis spectral measurements.
Abstract: A new four-coordinate cobalt(II) complex with 1,3-bis(1-ethylbenzimidazol-2-yl)-2-oxopropane (Etobb), Co(Etobb)Cl2, has been synthesized and characterized by elemental analysis, electrical conductivities, infrared, and UV-Vis spectral measurements. The crystal structure has been determined by single-crystal X-ray diffraction. Cobalt(II) is a distorted tetrahedral geometry, surrounded by two nitrogens from Etobb and two chlorides. DNA-binding properties of Etobb and its Co(II) complex have been investigated by electronic absorption, fluorescence, and viscosity measurements. The experimental results suggest that the ligand and its Co(II) complex bind to DNA via intercalation, and the binding affinity of the Co(II) complex to DNA is greater than Etobb.
TL;DR: The metal coordination geometry in the active site of metalloproteins is very different from the one of small inorganic complexes, due to the inflexibility of the ligand set from amino acid side chains.
TL;DR: In this paper, four new coordination polymers were synthesized and characterized by thermal analysis, vibrational spectroscopy (Raman and infrared) and single crystal X-ray diffraction analysis, where DPS ligands are coordinated to metal sites in a bridging mode and the carboxylate moiety of BT ligands adopts a monodentate coordination mode.