Molecules Of Cu Research Articles

Probing the electronic structure, chemical bonding, and excitation spectra of [CuE]+/0/−(E = 14 group element) diatomics employing DFT andab initiomethods

The electronic structure, chemical bonding, and excitation spectra of neutral, cationic, and anionic diatomic molecules of Cu and 14 group elements formulated as [CuE](+/0/-) (E = C, Si, Ge, Sn, Pb) were investigated by density functional theory (DFT) and time-dependent (TD)-DFT methods. The electronic and bonding properties of the diatomics analyzed by natural bond orbital (NBO) analysis approch revealed a clear picture of the chemical bonding in these species. The spatial organization of the bonding between Cu and E atoms in the [CuE](+/0/-) (E = Si, Ge, Sn, Pb) molecules can easily be recognized by the cut-plane electron localization function representations. Particular emphasis was given on the absorption spectra of the [CuE](+/0/-) which were simulated using the results of TD-DFT calculations employing the hybrid Coulomb-attenuating CAM-B3LYP functional. The absorption bands have thoroughly been analyzed and assignments of the contributing principal electronic transitions associated to individual excitations have been made.

Molecular structure of N,N′-o-phenylene-bis(salicylideneaminato)copper(II) studied by gas-phase electron diffraction and quantum-chemical calculations

The molecular structure of N,N′-o-phenylene-bis(salicylideneaminato)copper(II) (Cu(saloph)) was determined using the combination of gas-phase electron diffraction (GED), mass spectrometry, and quantum-chemical calculations. According to both experimental and theoretical approaches the molecule of Cu(saloph) is planar and possesses C2v symmetry. Main structural parameters determined by GED experiment are the following (total error is given in a brackets): rh1(Cu–N) = 1.960(20) A, rh1(Cu–O) = 1.913(17) A, ∠NCuN = 82.7(18)°, ∠OCuO = 91.6(21)°, ∠NCuO = 92.9(9)°. The experimental structural parameters of Cu(saloph) molecules determined by X-ray single crystal analysis and GED experiments were discussed and compared to the theoretical ones.

Vibrational Excitations in Single Trimetal-Molecule Transistors

Single-molecule transistors incorporating trimetal molecules of Cu(3)(dpa)(4)Cl(2) and Ni(3)(dpa)(4)Cl(2) (dpa = 2,2'-dipyridylamide) have been fabricated. Conductance is measured as a function of bias and gate voltages at low temperature, showing single-electron tunneling behavior through the molecules. Additional structures corresponding to the excitations in the molecules are observed, which can be attributed to intramolecular vibrational excitations coupled to the electron tunneling processes. The energies of the vibrational states are dependent on the redox state of the included molecules.

Coordination complexes of 2-(4-quinolyl)nitronyl nitroxide with M(hfac)(2) [M = Mn(II), Co(II), and Cu(II)]: syntheses, crystal structures, and magnetic characterization.

Three new complexes of the formula M(2)L(2) derived from 2-(4-quinolyl)nitronyl nitroxide (4-QNNN) and M(hfac)(2) [M = Mn(II), Co(II), and Cu(II)], (4-QNNN)(2).[Mn(hfac)(2)](2) (1), (4-QNNN)(2).[Co(hfac)(2)](2).2H(2)O (2), and (4-QNNN)(2).Cu(hfac)(2).Cu'(hfac)(2) (3), were synthesized and characterized structurally as well as magnetically. Complexes 1 and 2 are four-spin complexes with quadrangle geometry, in which both the nitrogen atoms of quinoline rings and oxygen atoms of nitronyl nitroxides are involved in the formation of coordination bonds. For complex 3, however, the nitrogen atoms of quinoline rings are coordinated with Cu(II) ion to afford a three-spin complex, which is further linked to another molecule of Cu(hfac)(2) (referred to as Cu'(hfac)(2)) to form a 1D alternating chain. The magnetic behaviors of the three complexes were investigated. For complex 1, as the nitronyl nitroxides and Mn(II) ions are strongly antiferromagnetically coupled, consequently its temperature dependence of magnetic susceptibility was fitted to the model of spin-dimer with S = 2, yielding the intradimer magnetic exchange constant of J = -0.82 cm(-1). For complex 2, the temperature dependence of the magnetic susceptibility in the T > 50 K region was simulated with the model of two-spin unit with S(1) = 3/2 and S(2) = 1/2, leading to J = -321.9 cm(-1) for the magnetic interaction due to Co(II).O coordination bonding, D = -16.3 cm(-1) (the zero-field splitting parameter), g = 2.26, and zJ = -3.8 cm(-1) for the magnetic interactions between Co(II) ions and nitronyl nitroxides through quinoline rings and those between nitronyl nitroxides due to the short O.O short contacts. The temperature dependence of magnetic susceptibility of 3 was approximately fitted to a model described previously affording J(1) = -6.52 cm(-1) and J(2) = 3.64 cm(-1) for the magnetic interaction between nitronyl nitroxides and Cu(II) ions through the quinoline unit via spin polarization mechanism and the weak O.Cu coordination bonding, respectively.

The Molecular Structure of Different Species of Cuprous Chloride from Gas‐Phase Electron Diffraction and Quantum Chemical Calculations.

AbstractFor Abstract see ChemInform Abstract in Full Text.

The molecular structure of different species of cuprous chloride from gas-phase electron diffraction and quantum chemical calculations.

The molecular geometry of gaseous cuprous chloride oligomers was determined by gas-phase electron diffraction at two different temperatures. Quantum chemical calculations were also performed for Cu(n)Cl(n) (n=1-4) molecules. A complex vapor composition was found in both experiments. Molecules of Cu(3)Cl(3) and Cu(4)Cl(4) were present at the lower temperature (689 K), while dimeric molecules (Cu(2)Cl(2)) were found in addition to the trimers and tetramers at the higher temperature (1333 K). All Cu(n)Cl(n) species were found to have planar rings by both experiment and computation. The bond lengths from electron diffraction (r(g)) at 689 K are 2.166+/-0.008 A and 2.141+/-0.008 A and the Cu-Cl-Cu bond angles are 73.9+/-0.6 degrees and 88.0+/-0.6 degrees for the trimer and the tetramer, respectively. At 1333 K the bond lengths are 2.254+/-0.011 A, 2.180+/-0.011 A, and 2.155+/-0.011 A, and the Cu-Cl-Cu bond angles 67.3+/-1.1 degrees, 74.4+/-1.1 degrees, and 83.6+/-1.1 degrees for the dimer, trimer, and tetramer, respectively.

Synthesis, spectroscopic characterization, and structural studies of new Cu(I) and Cu(II) complexes containing organophosphorus ligands, and crystal structures of (Ph3P)2Cu[S2PMe2], (Ph3P)2Cu[(OPPh2)2N], Cu[(OPPh2)2N]2, and Cu[(OPPh2)(SPPh2)N]2

The Cu(I) complexes, (Ph3P)2CuL (L = [S2PMe2]-, [OSPR2]- (R = Me, Ph), [(XPR2)(YPR'2)N]- (X, Y, R, R' = O, O, Ph, Ph; O, S, Ph, Ph; O, S, OEt, Ph; S, S, Me, Me)) and Cu(II) complexes, CuL2 (L = [(XPR2)(YPR'2)N]- (X, Y, R, R' = O, O, Ph, Ph; O, S, Ph, Ph)), have been prepared. The Cu(I) derivatives were characterized by multinuclear NMR spectroscopy and in two cases by X-ray crystallography. (Ph3P)2Cu[S2PMe2] (1) crystallizes in the orthorhombic space group P212121 (No. 19) with cell parameters a = 9.782(2), b = 17.808(4), c = 20.216(4) Å, V = 3521(6) Å3 and Z = 4, and (Ph3P)2Cu[(OPPh2)2N] (4) in the triclinic space group P[Formula: see text] (No. 2) with cell parameters a = 9.8079(2), b = 12.9141(3), c = 22.5666(5) Å, α = 75.714(2), β = 79.465(2), γ = 68.2770(8)°, V = 2559.9(1) Å3 and Z = 2. In both cases the phosphorus ligands are bidentate, thus resulting in monomeric molecules that contain tetrahedral CuP2S2 and CuP2O2 cores. The molecular structures of two of the Cu(II) derivatives were also determined. Cu[(OPPh2)2N]2 (8) and Cu[(OPPh2)(SPPh2)N]2 (9) crystallize in the triclinic space group P[Formula: see text] (No. 2) with cell parameters a = 8.887(2), b = 10.739(2), c = 12.477(3) Å, α = 77.61(3), β = 76.15(5), γ = 79.46(3)°, V = 1118.3(4) Å3 and Z = 1 for 8, and a = 9.626(2), b = 14.151(3), c = 24.752(5) Å, α = 88.23(3), β = 79.93(3), γ = 89.77(3)°, V = 3181(1) Å3 and Z = 3 for 9. The molecule of Cu[(OPPh2)2N]2 (8) has a planar CuO4 core, while in Cu[(OPPh2)(SPPh2)N]2 (9) both planar and tetrahedral copper cores are observed in a ratio of 1:2.Key words: structure, copper, thiophosphinates, oxo- and thio-imidodiphosphinates

Utilization of the copper(II) complex with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol as an absorption spectroscopic probe for nucleic acids assay

Based on the binding interaction of nucleic acids and the copper(II) complex with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (5-Br-PADAP), a new spectrophotometric assay for nucleic acids is described. At pH 5.7–7.5 the binding reaction is completed within 2 min at room temperature, and causes an absorbance decrease at the wavelength of maximum absorption of the complex, 553 nm. The calibration graphs for calf thymus DNA, fish sperm DNA, and yeast RNA are linear up to 14.5, 16.0 and 14.0 μg ml −1, respectively, and their 3 σ detection limits are correspondingly 84, 94 and 99 ng ml −1. Compared with some existing assays, the new method is sensitive, stable, simple, reproducible and relatively free from interference from co-existing species. The analytical results of synthetic samples are satisfactory, with relative standard deviations of five determinations of 0.52–1.94%. The association constant of calf thymus DNA with the complex is estimated by two graphical methods; every base pair of the nucleic acid can bind one molecule of Cu(II)–5-Br-PADAP complex with a 1 : 1 mole ratio of Cu(II) to 5-Br-PADAP.

Structure of μ-pyrazine-bis[bis(hexafluoroacetylacetonato)copper(II)

The title structure, μ-pyrazine-bis[bis(1,1,1,5,5,5-hexafluoro-2,4-pentanedionato)copper(II)], consists of a centrosymmetric dimer containing a bridging molecule of pyrazine. The pyrazine is essentially planar and coordinates axially to two symmetry related molecules of Cu(F 6 acac) 2 , where acac is acetylacetone [Cu(1)-N(1)=2.248 (6) A]. The Cu atoms have square-pyramidal coordination geometries and are displaced by 0.235 (5) A from the least squares plane defined by the four O atoms of the basal F 6 acac - ligands

The topography of isolated molecules of copper–phthalocyanine adsorbed on GaAs(110)

Single molecules of Cu–phthallocyanine (CuPc) have been investigated on a GaAs (110) substrate under UHV conditions. Prior to the measurement, a tunneling experiment on a silver substrate covered with about one monolayer of CuPc was performed. By this procedure a few molecules are transferred to the tunneling tip. When tunneling on GaAs some of these molecules can be redeposited on the freshly cleaved (110) surface. The ring structure and the fourfold symmetry of the molecule can be clearly recognized on the atomic flat surface of GaAs. In a few cases, a deep dip in the middle of the molecule is visible.

Liquid Chromatography of Sugars on Diol Columns. Detection with Cuprammonium Reagent

Abstract Post column reaction of sugars with cuprammonium reagent is discussed. Formation of the complex involves two molecules of carbohydrate and one molecule of Cu(NH3)4(H2O)2 2+ with the result of a shift towards longer wavelength in UV spectrum. 1 nanomole of fructose is detected, the reaction is simple, fast allowing very short reaction coil which does not increase band broadening it thus matches most of the requirements in the analysis of sugars in food products. Diol bonded silica is much less retentive than amino bonded silica and cannot compete in the separation of complex mixtures of sugars but is well suited for the analysis of one reducing sugar as important losses occur with NH, columns. Diol phase is well adapted to the separation of oligosaccharides. The use of HPLC as a means of determining all types of sugars has greatly increased for the last years. Many types of packings (bare silica, ion exchange with Na+ or Ca2+, alkyl or amino bonded silica) are available and have been advocated (1)...

The crystal structure of tetrammine copper sulphate Cu(NH3)4SO4·H2O

The crystal structure of tetrammine copper sulphate was determined. The orthorhombic unit cell with dimensions a=12.12, b=10.66, c==7.07 Acontains four molecules of Cu(NH3)4SO4.H2O, the space group is Pbnm (D2h16).The atomic coordinates were determined from the projections of the Patterson function and the electron density onto the (001) and (010) planes. The complex cation Cu(NH3)4++is approximately planar, the groups of NH3are linked by co-valent bonds to the central Cu atom. The average distance of the groups of NH3,which are approximately at the corners of a square surrounding the central Cu atom, is 2.90 A, the distance Cu-NH3,corresponding to the co-valent bond, is 2.05 A.