Adducts of zinc and copper(II) dialkyldithiocarbamate complexes with dialkylamines: Synthesis,EPR, and <Superscript>13</Superscript>C and <Superscript>15</Superscript>N CP/MAS NMR

Crystalline adducts of zinc and copper(II) dithiocarbamate (Dtc) complexes with dialkylamines [M(NHR′₂)(S₂CNR₂)₂] (M = Zn, ⁶³Cu, ⁶⁵Cu; R = CH₃, C₂H₅, or R₂ = (CH₂)₄O; R′ = C₂H₅, C₃H₇) have been preparatively isolated. The structures and spectral properties of the adducts have been studied by EPR and ¹³C and ¹⁵N MAS NMR. Chemisorption of bases on powders of dinuclear dithiocarbamates leads to their dissociation into monomeric adducts. Computer simulation demonstrates that the experimental EPR spectra of isotope-substituted copper(II) adducts have an individual character. The geometry of the copper polyhedra is intermediate between a trigonal bipyramid (TBP) and a tetragonal pyramid (TP). The TBP and TP contributions have been quantified based on EPR data. ¹³C and ¹⁵N MAS NMR data show that the Dtc ligands incorporated into the zinc adduct molecule are structurally nonequivalent. The dependence of the isotropic ¹⁵N chemical shifts of the Dtc groups on the alkyl substituents at the nitrogen atom is interpreted based on the concept of joint manifestation of the (+)inductive effect of the alkyl substituents and the mesomeric effect of the Dtc groups.     

Adducts of zinc and copper(II) dimethyland diethyldithiocarbamates with piperidine: Synthesis, EPR, solid-state natural abundance 13C and 15N CP/MAS NMR and single-crystal X-ray diffraction studies

Crystalline adducts of zinc and copper(II) dimethyl-and diethyldithiocarbamates with piperidine (Pip) of the general formula [M{NH(CH₂)₅}(S₂CNR₂)₂] (M = Zn and ⁶³Cu; R = CH₃ and C₂H₅) were obtained. Their structures and spectroscopic characteristics were studied by X-ray diffraction analysis, EPR spectroscopy, and solid-state natural abundance ¹³C and ¹⁵N MAS NMR spectroscopy. The most substantial differences between the adducts of the formula [Zn{NH(CH₂)₅}(S₂CNR₂)₂] (R = CH₃ and C₂H₅) were found in the spatial orientations of the coordinated heterocycles and the geometries of the zinc polyhedra. The individual character of the EPR spectra of magnetically diluted isotope-substituted copper(II) adducts was determined by computerassisted modeling. The adducts of copper(II) and zinc dimethyldithiocarbamates proved to exist as two isomers. The coordination polyhedra of copper(II) and zinc are intermediate between a tetragonal pyramid (TP) and a trigonal bipyramid (TBP). The contributions from the TBP/TP components to the coordination polyhedra were quantitatively estimated from X-ray diffraction data. The ¹³C and ¹⁵N NMR signals were assigned to the positions of the atoms of the =NC(S)S^? groups in the resolved (according to X-ray diffraction data) molecular structures of the adducts.     

Structural organization of mercury(II) and copper(II) dithiocarbamates from EPR and <Superscript>13</Superscript>C and <Superscript>15</Superscript>N MAS NMR spectra and X-ray diffraction analysis

The structures and spectroscopic properties of mononuclear and binuclear mercury(II) and copper(II) complexes with four dithiocarbamate ligands R₂NC(S)S^? (R = CH₃, C₂H₅, or iso-C₃H₇; R₂ = (CH₂)₆) were studied by solid-state ¹³C and ¹⁵N CP/MAS NMR and EPR spectroscopy. Mercury(II) N,N-cyclohexamethylenedithiocarbamate [Hg₂{S₂CN(CH₂)₆}₄] was obtained and characterized in detail by X-ray diffraction analysis at 299 K. The binuclear molecule of the complex is centrosymmetric; the central tricyclic fragment [Hg₂S₄C₂] is in the chair conformation. In the ¹³C and ¹⁵N NMR spectra, the signals were assigned to the dithiocarbamate ligands with different structural functions: bidentate chelating and combined (both chelating and bridging) ones. The differences between the isotropic ¹⁵N chemical shifts for the dialkyldithiocarbamate ligands were interpreted in terms of combination of the mesomeric effect of the =NC(S)S-groups and the inductive effect of the alkyl substituents. According to the EPR data, copper(II) in magnetically diluted systems is mainly found in heterobinuclear molecules [CuHg(S₂CNR₂)₄] and the geometry of the chromophores [CuS₅] approximates to a tetragonal pyramid.     

Structural Organization of Nickel(II), Zinc(II), and Copper(II) Complexes with Diisobutyldithiocarbamate: EPR, <Superscript>13</Superscript>C and <Superscript>15</Superscript>N CP/MAS NMR,and X-Ray Diffraction Studies

The structures and spectroscopic properties of nickel(II), zinc(II), and copper(II) complexes with dibutyl- and diisobutyldithiocarbamate were studied by EPR and ¹³C and ¹⁵N CP/MAS NMR spectroscopy and X-ray diffraction analysis. According to the EPR data, copper(II) forms mononuclear [^63/65Cu{S₂CNR₂}₂] and heterobinuclear complexes [^63/65CuZn{S₂CNR₂}₄] under magnetic dilution conditions. The isomeric forms of nickel(II) and zinc(II) diisobutyldithiocarbamates were detected by ¹³C and ¹⁵N NMR spectroscopy. The crystalline zinc(II) diisobutyldithiocarbamate was found to have a unique structural organization with alternating mononuclear [Zn{S₂CN(i-C₄H₉)₂}₂] and binuclear molecular forms [Zn₂{ S₂CN(i-C₄H₉)₂}₄] in the 1 : 1 ratio.     

Synthesis,structure, and thermal properties of benzene-solvated forms of bis(dimethyldithiocarbamato)piperidinezinc and -copper(II)

Solvated adducts of zinc and copper(II) dimethyldithiocarbamate complexes with piperidine of the general formula [M{NH(CH₂)₅}{S₂CN(CH₃)₂}₂] · C₆H₆ (M = Zn (I), ⁶³Cu (II)) were isolated on a preparative scale. According to X-ray diffraction data, compound I has a clathrate type structure: the benzene molecules located between the coordinated piperidine rings of neighboring adduct molecules are held by hydrogen bonds. Thermal destruction of I studied by simultaneous thermal analysis includes the desorption steps of benzene solvate molecules and inner-sphere piperidine molecules and thermolysis of the “dithiocarbamate part” of the adduct to give ZnS as the final product. The triaxial anisotropy pattern of EPR parameters of the isotope-substituted magnetically diluted adduct II indicates that the geometry of the copper coordination polyhedron is intermediate between a tetragonal pyramid (TP) and trigonal bipyramid (TBP). It was shown solvation of the adduct [⁶³Cu{NH(CH₂)₅}{S₂CN(CH₃)₂}₂] resulting a considerable increase in the contribution of the TBP component.     

Green,purple, blue — [Cu(N-Methylimidazole)<Subscript>n</Subscript> (OOCCH<Subscript>3</Subscript>)<Subscript>2</Subscript>]<Subscript>m</Subscript>, what is in a colour

Starting from the paddlewheel complex copper(II)acetate, the green N-methylimidazole adduct of copper(II)acetate is formed and transformed into the monomeric and dimeric N-methylimidazole adducts of copper(II)acetate [Cu(C₄H₆N₂)₂(CH₃COO)₂]_n·xH₂O (n = 1,2; x = 0, 6). The formation of the blue dimer or the purple monomer depends on the solvent and the presence or absence of water.     

Isomerization of silicenium and germenium ions in the systems C<Subscript>4</Subscript>H<Subscript>11</Subscript>M<Superscript>+</Superscript> (M = Si,Ge)

Equilibrium structures of the isomers and transition states of their interconversion in the system C₄H₁₁M⁺ (M = Si, Ge) have been obtained at theB3LYP level of theory using the cc-pVTZ basis set. The structures of these stationary points are close for Si and Ge; the most stable isomer in both systems is the tertiary cation (C₂H₅)(CH₃)₂M⁺, the second in energy is complex with ethylene [(CH₃)₂HM·C₂H₄]⁺. The secondary cation (C₂H₅)₂HM⁺ is third in energy isomer, the height of the barrier of interconversion for these three cations being practically independent on M. However, for M = Ge a substantial decrease in the energy of isomeric forms corresponding to complexes with alkanes is observed. As a result, in the system C₄H₁₁Ge⁺ the fourth in energy is isomer [(C₂H₅)Ge·C₂H₆]⁺ rather than [(C₂H₅)H₂Ge·C₂H₄]⁺ as for M = Si. Nevertheless, the height of the barriers for transition into these structures, although decreasing from M = Si to Ge, remain rather high, and the most favorable route of decomposition in both systems is the elimination of ethylene.     

Oxidative dehydrogenation of N-(2-hydroxy-3,5-R<Superscript>1</Superscript>,R<Superscript>2</Superscript>-benzyl)-4-aminoantipyrines in the complexation reaction

Reactions of N-(2-hydroxy-3,5-R¹,R²-benzyl)-4-aminoantipyrines with copper acetate in ethanol gave complexes with Schiff bases (SBs) rather than the expected complexes with reduced SBs; i.e., the starting ligands undergo oxidative dehydrogenation during the complexation reaction. The corresponding complexes with reduced SBs were obtained from sodium salts of the ligands and cupric sulfate in aqueous solutions. Kinetic measurements showed that oxidative dehydrogenation occurs in the heteroleptic complexes Cu(L ⁱ )(CH₃COO)(X) (L ⁱ H are derivatives of N-(2-hydroxy-3,5-R¹,R²-benzyl)-4-aminoantipyrines; i = 6–10; X = H₂O, CH₃OH, CH₃CH₂OH) but does not occur in the complexes CH₃OH, CH₃CH₂OH. The absence of oxidative dehydrogenation of the ligands in Cu(L ⁱ )₂ · H₂O can be explained by the octahedral environment of the Cu²⁺ ion and, accordingly, the absence of the coordination site for molecular oxygen. The molecular structures of two Cu(II) complexes with SBs were determined by X-ray diffraction.     

Vinylimidazole copolymers: coordination chemistry,solubility, and cross-linking as function of Cu<Superscript>2+</Superscript> and Zn<Superscript>2+</Superscript> complexation

P(1-VIm-co-MMA) copolymers with 4 or 44 wt.% 1-VIm (abbreviated PVM-4 and PVM-44) where polymerized from 1-VIm (1-vinylimidazole) and methylmethacrylate with azobisisobutyronitrile as initiator and reacted with either Cu²⁺ or Zn²⁺. The resulting coordinated polymer complexes were studied using ICP-AES, CP/MAS ¹³C NMR, conductivity measurements, vibrational spectroscopy (mid-FTIR and far-FTIR), DSC, and EPR. It was established by ICP-AES, CP/MAS ¹³C NMR, conductivity, mid-FTIR and EPR measurements that the transition metal ions in the complexes were exclusively coordinated by the imidazole ligand. The coordination geometry is square planar with regard to Cu(II) complexes. The strong interaction between the polymeric imidazole ligand and the transition metal ion cross-links the system, resulting in augmentation of T _g (the glass transition temperature), especially for copolymers with high relative amount of 1-VIm. The effect of changing metal ion is more complicated and depends on both the strength of the coordinate interaction as well as the coordination number. The solubility of the coordinate polymer complex in conventional solvents is low due to the coordinate cross-links. However, the coordinate polymer complexes are soluble in strongly coordinating solvents such as acetonitrile and dimethylsulfoxide.     

Extraction of metal ions (Fe<Superscript>3+</Superscript>, Co<Superscript>2+</Superscript>, Ni<Superscript>2+</Superscript>, Cu<Superscript>2+</Superscript> and Zn<Superscript>2+</Superscript>) using immobilized-polysiloxane iminobis(n-2-aminophenylacetamide) ligand system

A new insoluble solid functionalized ligand system bearing chelating ligand group of the general formula P-(CH₂)₃-N[CH₂CONH(C₆H₄)NH₂]₂, where P represents [Si–O] _n polysiloxane network, was prepared by the reaction of the immobilized diethyliminodiacetate polysiloxane ligand system, P-(CH₂)₃N(CH₂CO₂Et)₂ with 1,2-diaminobenzene in toluene. ¹³C CP-MAS NMR, XPS and FTIR results showed that most ethylacetate groups (–COOEt) were converted into the amide groups (–N–C=O). The new functionalized ligand system exhibits high capacity for extraction and removal of the metal ions (Fe³⁺, Co²⁺, Ni²⁺, Cu²⁺ and Zn²⁺) with efficiency of 95–97% after recovery from its primary metal complexes. This functionalized ligand system formed 1:1 metal to ligand complexes.     

Structures and mutual transformations of isomers of germylium ions (CH<Subscript>3</Subscript>)H<Subscript>2</Subscript>Ge<Superscript>+</Superscript> and (CH<Subscript>3</Subscript>)<Subscript>2</Subscript>HGe<Superscript>+</Superscript> and their silicon analogs

The potential energy surfaces of the (CH₃)_nH_3?n M⁺ ions, where n = 1, 2; M = Si, Ge, were scanned using the B3LYP method with 6–31G* and aug-cc-pVDZ basis sets. The major attention was given to isomeric species having the form of complexes of the HM⁺ and CH₃M⁺ ions with hydrogen, methane, and ethane molecules. These species were characterized previously neither by experimental nor by theoretical methods. It was found that these species become more stable in going from Si to Ge; the complex [CH₃Ge⁺CH₄] is the second isomer in the energy after (CH₃)₂HGe⁺. However, the heights of the activation barriers to formation of these complexes from the most stable isomer, though decreasing in going from Si to Ge, remain relatively high and, what is particularly important, somewhat exceed the activation barrier to formation of the complex [H₃Ge⁺·C₂H₄].     

Copper(II) and Nickel(II) Alkylxanthate Complexes (R = C2H5, i-C3H7, i-C4H9, s-C4H9, and C5H11): EPR and Solid-State 13C CP/MAS NMR Studies

Alkylxanthate complexes of the general formula [M{S(S)COR}₂] (M = Ni, ⁶³Cu, and ⁶⁵Cu; R = C₂H₅, i-C₃H₇, i-C₄H₉, s-C₄H₉, and C₅H₁₁) were synthesized and studied by EPR and high-resolution solid-state ¹³C CP/MAS NMR. In the copper(II) complexes stabilized in the matrix of nickel(II) compounds, square planar chromophores [CuS₄] are characterized by rhombic distortion (EPR data). Experimental EPR spectra were simulated at the second order of perturbation theory. Nickel(II) complexes were characterized by ¹³C NMR spectra. In all cases, the –OC(S)S– groups were found to exhibit intramolecular structural equivalence.     

Experimental and theoretical study of <Superscript>13</Superscript>C shielding tensors in new-style molybdenum complex

¹³C 2D-PASS spectra of two new cis-dioxo catecholatomolybdenum complexes (NH₂CH₂NH₂CHCH₂)₂(H⁺)₃[Mo^vO ₂(C₆H₄O₂)₂] and (NH₂CH₂CH₂CH₂NH₂)₂(H⁺)₃[Mo^(v)O₂ (C₂H₂O₂)₂] have been obtained by solid-state nuclear magnetic resonance (NMR), in which the spinning sidebands were well-separated. The principal components of the ¹³C shielding tensors were extracted by theoretically fitting the intensities of ¹³C spinning sidebands. The effects of counter cations on ¹³C chemical shift isotropy and shielding tensor of cis-dioxo catecholatomolybdenum complex anion [Mo ^(v)O₂(C₆H₄O₂)₂]³⁻ were studied, comparing the ¹³C CSA of those carbon sites in complex anions with that of the counter cations. Based on the known structure of the molybdenum complex crystal, theoretical values of ¹³C shielding tensors were calculated by the ainitio GIAO method, in comparison with the experimental results.     

Formation of Cu<Superscript>I</Superscript>(CH<Subscript>3</Subscript>CN)<Subscript>4</Subscript>ClO<Subscript>4</Subscript> in the reactions of copper(II) perchlorate with acetonitrile in the presence of sulfur-containing organic compounds

Cu(ClO₄)₂·6H₂O was shown to react with 2,2′-[propane-1,3-diylbis(thio-2-phenylnemethylidene]-bis(3-pyridylamine) (I) or (5Z)-2-ethoxycarbonylmethyl-(2-pyridylmethylidene)-3,5-dihydro-4H-imidazol-4-one (II) in the presence of CH₃CN with the reduction of copper(II) to copper(I) and the formation of the tetrahedral complex Cu^I(CH₃CN)₄ClO₄ (III). In the course of the reaction the organic ligands I and II were oxidized to the corresponding sulfoxides.     

<Superscript>1</Superscript>H and <Superscript>31</Superscript>P nuclear spin-lattice relaxation in C-phosphorylated oximes

The ¹H spin-lattice relaxation times of the proton-bearing groups and the ³¹P spin-lattice relaxation times in C-phosphorylated oximes R¹C(=NOH)P(=O)R²R³ (R¹ = Ph, R² = R³ = OMe; R¹ = Ph, R² = OMe, R³ = OCH²CH²Br; R¹ = PhCH², R² = R³ = OCHMe²) and dioxime R²P(=O)C(=NOH)(CH₂)₄C(=NOH)P(=O)R² (R = OMe) in DMSO-d₆ were measured. The characteristic reorientation times of the whole molecules were estimated using the measured values of the ¹H relaxation times and the results of semiempirical PM3 quantum chemical calculations of the molecular geometries. The reorientation times were used to identify the contributions of different relaxation mechanisms to the rate of ³¹P spin-lattice relaxation. The anisotropy of the chemical shielding of ³¹P nuclei was evaluated from the difference between the ³¹P relaxation rates measured at 101.27 and 161.92 MHz.     

Crystalline cadmium dialkyl phosphorodithioate complexes: Synthesis and structural organization as probed by multinuclear <Superscript>13</Superscript>C, <Superscript>31</Superscript>P,and <Superscript>113</Superscript>Cd CP/MAS NMR and single-crystal X-ray diffraction

The cadmium O,O′-dethyl (I) and O,O′-di-sec-butyl phosphorodithioate (II) complexes have been synthesized and characterized in detail by ¹³C, ³¹P, and ¹¹³Cd CP/MAS NMR. X-ray crystallography shows that complex II has a binuclear molecular structure [Cd₂{S₂P(O-s-C₄H₉)₂}₄]. For ³¹P and ¹¹³Cd NMR signals, the chemical shift anisotropy δ_aniso and the asymmetry parameter η have been calculated. The ³¹P NMR signals are assigned to the terminal and bridging ligands in the complexes.     

Solvent extraction of radioactive Cs<Superscript>+</Superscript> by hydroborate anionic extractants of the [1-LB<Subscript>10</Subscript>H<Subscript>9</Subscript>]<Superscript>-</Superscript> type (L = amine or phosphine)

Summary New anion derivatives of the closo-decaborate [B₁₀H₁₀]^2- bearing amine or phosphine groups were tested for the extraction of radioactive cesium cations in acidic medium. The technique used is the liquid-liquid extraction based on the complexation of Cs⁺ by these anions to form neutral compounds which are extracted by organic solvents (diluents) of medium polarity. Promising results were obtained with the anion [1-(C₆H₅CH₂)₂(C₆H₅)NB₁₀H₉]^- (3) soluble in many organic solvents. The most efficient diluent for the extraction is nitrobenzene. Using hydrochloric acid or sulfuric acid in the aqueous medium instead of nitric acid does not significantly affect the efficiency of Cs⁺ extraction.     

Organic-inorganic hybrid perovskite (C<Subscript>6</Subscript>H<Subscript>5</Subscript>(CH<Subscript>2</Subscript>)<Subscript>2</Subscript>NH<Subscript>3</Subscript>)<Subscript>2</Subscript>CdCl<Subscript>4</Subscript>: Synthesis,structural and thermal properties

The present research work reports the study on crystal structure, vibrational spectroscopy and thermal analysis of organic-inorganic hybrid compound (C₆H₅(CH₂)₂NH₃)₂CdCl₄. Single crystals of bis(phenethylammonium)tetrachlorocadmate (C₆H₅(CH₂)₂NH₃)₂CdCl₄ (PEA–Cd) were obtained by diffusion at room temperature. This compound crystallizes in the orthorhombic space group C2cb with unit cell parameters a = 7.4444(2) Å, b = 38.8965(3) Å, c = 7.3737(2) Å and Z = 4. Single crystal structure has been solved and refined to R = 0.036 and wR = 0.092. The structure consists of an extended [CdCl₄]^2– network and two [C₆H₅(CH₂)₂NH₃]⁺ cations to form a two-dimensional perovskite system. The infrared (IR) spectrum of the title compound was recorded at room temperature. Differential scanning calorimetry (DSC) was used to investigate the phase transition; this compound exhibits a reversible single solid-solid phase transition.     

Electronic and Steric Structure of ClAsX<Subscript>2</Subscript> Molecules: Evaluation by <Superscript>35</Superscript>Cl NQR and Quantum-Chemical Calculations

Molecules of the series ClAsX₂ [X = C₂H₅, N(CH₃)₂, OCH₃] were studied by RHF/6-31G(d) and MP2/6-31G(d) calculations. Their ³⁵Cl NQR frequencies were calculated from the populations of the 3p constituents of the chlorine valence p orbitals. The features of interaction of the geminal atoms in the molecules and the effect of this interaction on the electron distribution in them were analyzed.     

Bis(dimethyldithiocarbamato)(pyridine)zinc and -copper(II) and Their Benzene Solvates: EPR and Solid-State Natural Abundance (13C, 15N) CP/MAS NMR

Adducts of bis(dimethyldithiocarbamato)zinc and -copper(II) complexes with pyridine, [M(Py)(Mdtc)₂], and their benzene solvates [M(Py)(Mdtc)₂] · 0.5C₆H₆ were synthesized. The electron paramagnetic resonance method and solid-state ¹³C and ¹⁵N CP/MAS NMR spectroscopy were used to perform a comparative study of the compounds obtained. The EPR data showed that the geometry of Cu(II) coordination polyhedra both in the adduct itself [Cu(Py)(Mdtc)₂], and in its solvate, [Cu(Py)(Mdtc)₂] · 0.5C₆H₆ is intermediate between a square pyramid (SP) and a trigonal bipyramid (TBP), the contribution from the latter being dominant (75%) in [Cu(Py)(Mdtc)₂]. In the solvated adduct [Cu(Py)(Mdtc)₂] · 0.5C₆H₆, the copper(II) polyhedron is distorted to form an SP-enriched structure (the contribution from TBP is reduced to 55%). It was found NMR data that [Zn(Py)(Mdtc)₂] exists in a single high-symmetry molecular form. Coordinated pyridine molecule shows molecular motion about the Zn–N bond. The solvation of the adduct results in structural nonequivalence of the Mdtc^–ligands in [Zn(Py)(Mdtc)₂] · 0.5C₆H₆. Signals in the ¹⁵N NMR spectra were assigned to the structural positions of the atoms in the previously described molecular structure of a solvated adduct. It was found that the heterogeneous reaction of adduct formation during the absorption of pyridine from the gas phase by polycrystalline [Zn₂(Mdtc)₄] species is accompanied by the dissociation of binuclear molecules.