Charge-transfer photochemistry of the ternary complex (dithio-diseleno-carbamato)copper(II)

Photolysis of the ternary system consisting of diethyldithiocarbamate (Et2dtc), diethyldiselenocarbamate (Et2dsc) and copper(II) (1:1:1) has been studied in isobutylmethylketone (IBMK), toluene, chloromethane and chloromethane/ROH solutions (chloromethane = CCl4, CHCl3 or CH2Cl2 and ROH = EtOH or i-PrOH). The results obtained by EPR techniques and UV-Vis data indicate that a homolytic Cu-S bond cleavage involving the dithiocarbamate (dtc) ligand appears as the primary photo-process in Cu(Et2dtc)(Et2dsc) photolysis. Further conversion of the primary photoproduct Cu(I)(Et2dsc) is discussed in terms of a specific interaction with the solvent. In chloromethanes and chloromethane/ROH Cu(I)(Et2dsc) is oxidised by the solvent to give the corresponding paramagnetic mixed-ligand Cu(II)(Et2dsc)Cl complex and/or its chloride-bridged and EPR silent dimer Cu2(Et2dsc)2Cl2. The formation of the monomeric species occurs through a co-ordination of the alcohol molecule in the xy plane of the complex. Because of its co-ordination inertness, toluene poorly stabilises the primary photoproduct Cu(I)(Et2dsc), thus providing an effective primary recombination process and lower efficiency of Cu(Et2dtc)(Et2dsc) photolysis. The formation of the bis-solvated mixed-ligand complex Cu(II)(Et2dsc)+ in IBMK is also discussed.     

Oxidation of bis(4-toluenesulphonyl-L-serinato)copper(II) to bis(formylglycine)copper(II)

Summary Oxidation of L-serine occurs on degradation of bis(L-serinato)copper(II) and at the same time copper is reduced.     

Crystal structures of bis(ethylenediamine) copper(II) diethyldithiophosphate and di(ethylenediamine)bis (diethyldithiophosphato) copper(II) thiocyanate

Journal of Structural Chemistry -     

EPR study on the ligand-exchange reaction between bis(diethyldiselenocarbamato)copper(II) and bis(octyldithiocarbonato)copper(II)

EPR study on the ligand-exchange reaction between bis(diethyldiselenocarbamato)copper(II), Cu(Et2dsc)2, and bis(octyldithiocarbonato)copper(II), Cu(octxant)2, in CH2Cl2, CHCl3, CCl4, C6H6 and C6H5.CH3 is reported for the first time. Mixing of equimolar amounts of the parents (chromophores CuSe4 and CuS4, respectively) in C6H6, C6H5.CH3 and CH2Cl2 makes EPR signals of both parents superimposed by the spectrum of a mixed-chelate Cu(xant)(dsc) complex (chromophore CuS2Se2). A new additional EPR spectrum appears in CHCl3 or CCl4 due to a five-coordinate mixed-ligand complex with the chromophore Cu(S3Se)S as follows by comparing the g-values of parents and mixed-ligand complexes. The appearance of this complex could be explained having in mind donor-acceptor properties of complexes, solvents and the resultant reaction of Cu(octxant)2 with the ester of diselenocarbamic acid yielded in Cu(Et2dsc)2 destruction by CCl4 or CHCl3.     

EPR study on ligand-exchange reaction between bis(diethyldiselenocarbamato)copper(II) and some bis(acetylacetonato)copper(II) complexes

The paper is a study on the formation and properties of mixed-chelate copper(II) complexes, in which one ligand is strongly covalently bound diselenocarbamate (dsc), and the other belongs to a series of differently substituted acetylacetonates (acac), all forming weak covalent bonds. Thenoyltrifluoro- and trifluoro- substituted acetylacetonates only partly form mixed-chelate complexes, stable in toluene, benzene or dichloromethane, but gradually decomposing in chloroform or carbontetrachloride by analogy with Cu(Et(2)dsc)(2) behavior in these solvents. Hexafluoro-acetylacetonato copper(II) completely turns into a mixed-chelate Cu(dsc)(hfacac), which remains unchanged for more than 8 months of monitoring in all solvents used. The stability of Cu(dsc)(hfacac) is attributed to the reduced remaining negative charge on selenium atom embarrassing the formation of weak D-A complex with haloalkanes. The obtained EPR parameters suggest significant lowering of the contribution of the 4s AO of copper(II) in the mixed-chelate complexes. It is shown that Cu(acac)(2) does not react with Cu(Et(2)dsc)(2).     

Homogeneous isotope exchange between copper(II) and bis(resacetophenone oxime)copper(II) complex

Isotope exchange behavior of bis(resacetophenone oxime)copper(II) complex with copper(II) in tri-n-butyl-phosphate and methanol medium has been studied. The studies were carried out at different temperatures varying the concentration of both metal ion and complex. The results show that the complex is labile in the kinetic sense. Increase in temperature increases the isotope exchange rate. The increase in concentration also results in enhancement of the rate of reaction.     

Infrared photochemistry of bis(trifluoromethyl) peroxide

Bis(trifluoromethyl) peroxide is readily dissociated by multiple infrared photon excitation at CO₂ laser wavelengths. The primary dissociation product is CF₃O; approximately 85% of the nascent radicals are further dissociated in the laser field to form CF₂O and F. The F atoms then react with the remaining CF₃O to produce CF₃OF. The formation of CF₃OF is strongly inhibited by addition of HI, which reacts preferentially with the F atoms.     

Reaction of halogens with copper(II) bis(diethyldithiocarbamate)

Conclusions It was established by EPR spectroscopy that the reaction of halogens with Cu(dtc)₂ has redox character in polar and nonpolar solvents. However, the ligand is oxidized in a polar solvent, and new complexes of copper(II), the coordination sphere of which is formed via different combinations of solvent molecules, halide ions, and dtc^–, are formed as a result of intraspheral transformations.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2484–2488, November, 1988.     

A urea adduct of bis(hinokitiolato)copper(II)

Bis(μ₂‐3‐isopropyl‐7‐oxocyclohepta‐1,3,5‐trien‐1‐olato)bis[(3‐isopropyl‐7‐oxocyclohepta‐1,3,5‐trien‐1‐olato)copper(II)]–urea–acetone (1/6/2), [Cu₂(C₁₀H₁₁O₂)₄]·6CH₄N₂O·2C₃H₆O, where 3‐isopropyl‐7‐oxocyclohepta‐1,3,5‐trien‐1‐olate is the systematic name for the hinokitiolate anion, contains three novel structural features. First, it contains a bis(hinokitiolato)copper(II) dimer, [Cu(hino)₂]₂, unlike any other, demonstrating that linkage isomerism is another avenue by which Cu(hino)₂ can transmute from one form to another. Second, [Cu(hino)₂]₂ is hydrogen bonded to two urea molecules, indicating that hydrogen bonding cannot yet be discounted from any proposed mechanism of action for the antimicrobial and antiviral properties of bis(hinokitiolato)copper(II). Finally, corrugated urea layers crosslinked by [Cu(hino)₂]₂ dimers are observed, suggesting that a new family of host–guest materials, i.e. metallo–urea clathrates, exists to challenge our understanding of crystal engineering and crystal growth and design. Selected details of the structure are that the [Cu(hino)₂]₂ dimers possess crystallographic inversion symmetry, the Cu atoms have square‐pyramidal coordination geometries, the basal Cu—O bonds are in the range 1.916 (2)–1.931 (2) Å, the apical Cu—O bond length is 2.582 (2) Å, the hinokitiolate bite angles are in the range 83.41 (7)–83.96 (8)°, the urea–Cu(hino)₂ interactions have an R₂²(8) motif, and the urea layers result from the close packing of R₈⁶(28) `butterflies' and R<sub>8</sub><sup>6</sup>(24) `strips of tape'.