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.     

Structural organization and thermal properties of crystalline copper(II) <Emphasis Type="Italic">N,N</Emphasis>-<Emphasis Type="Italic">cyclo</Emphasis>-hexamethylenedithiocarbamate: A manifestation of coordination polymerism

The first representative of copper(II) dithiocarbamate complexes with an unusual type of structural organization is synthesized. According to the X-ray diffraction data, the layers of noncentrosymmetric mononuclear [Cu{S₂CN(CH₂)₆}₂] and centrosymmetric binuclear [Cu₂?ub;S₂CN (CH₂)₆?ub;₄] molecules alternate in the crystalline lattice of copper(II) N,N-cyclo-hexamethylenedithiocarbamate. The mononuclear and binuclear forms of the complex are observed in the 2: 1 ratio. The thermal properties of the synthesized compound are studied by thermogravimetry and differential scanning calorimetry. The final product of the thermal destruction of the complex is CuS.     

Polynuclear thallium(I) N,N-cyclo-hexamethylenedithiocarbamate [Tl2{S2CN(CH2)6}2]n: Chemisorption properties and copper(II) fixation modes

The Cu²⁺ sorption properties of the polynuclear thallium(I) N,N-cyclo-hexamethylenedithiocarbamate complex [Tl₂{S₂CN(CH₂)₆}₂]n (I) are reported. The sorption capacity of the complex is ∼67 mg/g. According to EPR data, freshly precipitated I binds copper from the aqueous phase by chemisorption, which results in the formation of the β-form of the paramagnetic trinuclear complex [CuTl₂{S₂CN(CH₂)₆}₄] (containing a small amount of its α-form). Scanning electron microscopic data indicate cardinal reformation of the chemisorbent particles upon copper(II) sorption, including changes in the particle shape and size.     

Structures of polynuclear thallium(I) and copper(II)-thallium(I) complexes with dialkyldithiocarbamates: 13C and 15N CP/MAS NMR, EPR, and X-ray diffraction studies

A comparative study of polynuclear thallium complexes with dialkyldithiocarbamates [Tl₂{S₂CNR₂}₂]_n (R = CH₃, i-C₃H₇, C₄H₉, and i-C₄H₉; R₂ = (CH₂)₆) was performed by solid-state ¹³C and ¹⁵N CP/MAS NMR spectroscopy. The dithiocarbamate groups were found to be structurally equivalent in the complexes studied. An increase in the positive inductive effect of alkyl substituents at the N atom increased ¹⁵N chemical shifts as a result of a combination of positive inductive effect of the alkyl substituents and the mesomeric effect of=NC(S)S-groups. The first representative of thallium(I) complexes with a cyclic dithiocarbamate ligand [Tl₂{S₂CN(CH₂)₆}₂]_n was obtained. Its molecular structure was determined from X-ray diffraction data. The β-form of the isotope-substituted complex [^63/65CuTl₂{S₂CN(CH₂)₆}₄] was obtained and examined by EPR spectroscopy. The EPR spectra were modeled at the second order of the perturbation theory. The spin density at the thallium atoms was calculated and its distribution over the AOs of thallium was determined.     

Synthesis, structure, and thermal properties of tallium(I) N,N- cyclo -pentamethylenedithiocarbamate [Tl2{S2CN(CH2)5}2] n : X-ray diffraction, 13C and 15N MAS NMR, and thermal analysis studies (An example of complicated structural organization)

Crystalline polynuclear thallium(I) N,N-cyclo-pentamethylenedithiocarbamate is synthesized by the preparative synthesis. According to the MAS NMR (¹³C, ¹⁵N) data, its composition includes four structurally nonequivalent dithiocarbamate ligands. According to the X-ray diffraction data, the complex synthesized is a remarkable example for the self-organization of the chemical system with a simple composition into an unusually complicated structure. The latter includes three types of the nonequivalent binuclear molecules [Tl₂{S₂CN(CH₂)₅}₂] (I) performing various structural functions. Two of them (centrosymmetric) alternate and participate in infinite polymeric chain building. The third structural function (noncentrosymmetric) is associated with the joining of the polymeric chains into two-dimensional layers. Structurally nonequivalent binuclear molecules I are shown to be related as conformers. The study of the thermal properties of the complex shows that Tl₂ S is the final thermal destruction product. Original Russian Text ? T.A. Rodina, A.V. Ivanov, O.A. Bredyuk, A.V. Gerasimenko, 2009, published in Koordinatsionnaya Khimiya, 2009, Vol. 35, No. 3, pp. 172–180.     

ESR and solid-state natural abundance 13C CP/MAS NMR study of crystalline alkyl (R = C2H5, i-C3H7, i-C4H9, s-C4H9, and C5H11) xanthate copper(II) and thallium(I) complexes

Crystalline thallium(I) alkylxanthate complexes [Tl{S(S)COR}]_n (R = C₂H₅, i-C₃H₇, i-C₄H₉, s-C₄H₉, and C₅H₁₁) and isotope-substituted heteropolynuclear Cu(II)Tl(I) complexes [⁶³⁽⁶⁵⁾CuTl₆(S₂COR)₈] (R= i-C₄H₉ and C₅H₁₁) were obtained and studied by ESR and high-resolution solid-state ¹³C CP/MAS NMR spectroscopy. According to the ¹³C NMR data, polynuclear thallium(I) complexes contain structurally equivalent alkylxanthate ligands. The ESR study revealed the Jahn-Teller dynamic effect in Cu(II)Tl(I) complexes; the nuclei of six Tl atoms are involved in the hyperfine interaction.Translated from Koordinatsionnaya Khimiya, Vol. 31, No. 1, 2005, pp. 48–54.Original Russian Text Copyright © 2005 by Ivanov, Bredyuk, Antzutkin, Forsling.