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  • 1.
    Bredyuk, O.A.
    et al.
    Institute of Geology and Nature Management, Far East Branch, Russian Academy of Sciences.
    Loseva, Olga V.
    Institute of Geology and Nature Management, Far East Branch, Russian Academy of Sciences.
    Ivanov, Alexander V.
    Institute of Geology and Nature Management, Far Eastern Branch of the Russian Academy of Sciences .
    Gowda, Vasantha
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering. University of Oulu.
    Antzutkin, Oleg N.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering. Warwick University, Coventry.
    Three-Dimensional Polymeric Thallium(I) Morpholinedithiocarbamate [Tl2{S2CN(CH2)4O}2]n and Its Capability of Binding Gold(III) from Solutions: Chemisorption Synthesis of a Heteronuclear Gold(III)–Thallium(III) Complex of the Ionic Type, ([Au{S2CN(CH2)4O}2][TlCl4])n, the Role of Secondary Interactions Tl…O, Tl…S, and Au…S in the Supramolecular Self-Organization, 13C MAS NMR, and Thermal Behavior2017In: Russian journal of coordination chemistry, ISSN 1070-3284, E-ISSN 1608-3318, Vol. 43, no 10, p. 638-651Article in journal (Refereed)
    Abstract [en]

    Crystalline polymeric thallium(I) morpholinedithiocarbamate [Tl2{S2CN(CH2)4O}2]n (I) and the heteronuclear ion–polymeric gold(III)–thalium(III) complex ([Au{S2CN(CH2)4O}2][TlCl4])n (II) are preparatively isolated and characterized by X-ray diffraction analysis and 13C MAS NMR spectroscopy. According to the X-ray diffraction data, the main structural units of compounds I and II (CIF files CCDC 1548079 and 1548080) are presented by the binuclear centrosymmetric molecule [Tl2{S2CN(CH2)4O}2], noncentrosymmetric complex cation [Au{S2CN(CH2)4O{2]+, and isomeric complex anions [TlCl4]. The formation of the three-dimensional polymeric structure (coordination number of Tl is 7), which is not characteristic of thallium(I) dithiocarbamates, is a consequence of the participation of the secondary Tl…O and Tl…S bonds of two types in the supramolecular self-organization of compound I. Nonequivalent secondary interactions of the first type join the binuclear molecules [Tl2{S2CN(CH2)4O}2] into polymer layers, which, in turn, form the three-dimensional polymeric framework due to the secondary bonds Tl…S. The revealed ability of freshly precipitated compound I to the chemisorption of gold(III) from solutions (2 M HCl) makes it possible to obtain heteronuclear supramolecular complex II as an individual form of binding. In the structure of the latter, the pairs of stronger secondary Au…S bonds join the gold(III) cations into dimers [Au2{S2CN(CH2)4O}4]2+ of the angular structure, the structural ordering of which is achieved in the cationcationic polymeric chain ([Au2{S2CN(CH2)4O}4]2+)n of the helical type involving the pairs of less strong Au…S bonds between the adjacent binuclear units. The distorted tetrahedral anions [TlCl4] are localized between the polymeric chains. The study of the thermal behavior of compounds I and II by simultaneous thermal analysis makes it possible to establish the character of thermal transformations of the substances and to identify Tl2S (I), TlCl, and elemental gold (II) as thermolysis products

  • 2.
    Dinesha,
    et al.
    Department of Chemistry, Vivekananda College, Puttur, India.
    Viveka, S.
    Department of Chemistry, Mangalagangotri, Mangalore University, Konaje, India.
    Gowda, Vasantha
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering. Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering. NMR Research Group, Faculty of Science, University of Oulu, Oulu, Finland.
    Nagaraja, G.K
    Department of Chemistry, Mangalagangotri, Mangalore University, Konaje, India.
    Review: An experimental (synthesis, NMR and crystallography) and theoretical study of three biologically active diazoles2018In: Concept, property and application of micro/nanostructured materials / [ed] Li,J. & Du, S., Nova Science Publishers, Inc., 2018, p. 213-232Chapter in book (Refereed)
    Abstract [en]

    The current chapter overview to explain the synthesis of three important class of diazoles namely, pyrazoles, hydroxypyrazolines, and imidazoles followed by elucidation of structure by single-crystal X-ray crystallography, liquid state 1H and density functional theory (DFT) calculations. Our principal interest is focused on the relationship between molecular and/or crystal structure of the synthesized compounds and their efficacy as pharmaceutical drug molecules. Furthermore, they play a significant role as crucial synthetic intermediates. The synthesized molecules were tested for their biological activities like anticancer, antimicrobial, anti-inflammatory, analgesic and antioxidant agents. Strong intermolecular interactions mediated by hydrogen bonding C-H·O or p-p stacking has been observed in X-ray structures most of the molecules. DFT calculations of the NMR chemical shifts for the unambiguous structural assignments of the molecules were performed. Overall, a multidimensional approach has been used for rational design, synthesis and structural characterization of these biologically important molecules. The main goal of this chapter is to review our recent progress in this field. 

  • 3.
    Gowda, Vasantha
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Combined experimental and theoretical studies of dithiocarbamate complexes of yttrium, lanthanum and bismuth2014Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Metal-dithiocarbamate complexes find wide-ranging applications in nanomaterial and metalseparation science, and have potential use as chemotherapeutic, pesticides, and as additives tolubricants. A highly versatile dialkyldithiocarbamate (R2NCS2–) ligand can form stablecomplexes with all the transition elements and also the majority of main group, lanthanide andactinide elements. Here we present structural investigations of the molecular and electronicstructures of dialkyldithiocarbamate complexes with yttrium(III), lanthanum(III), andbismuth(III) of molecular formula [Y{S2CN(C2H5)2}3PHEN], [La{S2CN(C2H5)2}3PHEN], and[Bi2{S2CN-n(C4H9)2}6] (where PHEN=1,10-Phenanthroline) . The experimental solid-state 13Cand 15N cross polarization magic-angle-spinning (CP-MAS) NMR results are reported for allthese three complexes. We also report new single-crystal X-ray structures of heterolepticyttrium, lanthanum, and homoleptic bismuth dialkyldithiocarbamate complexes. Thecomparative analysis of powder XRD patterns and solid-state 13C and 15N CP-MAS spectra ofpolycrystalline yttrium(III) and lanthanum(III) diethyldithiocarbamato-phenanthrolinecomplexes shows the presence of significant structural differences. The diethyldithiocarbamatophenanthrolinecomplex of yttrium has a very similar structural type to a previously reported Xraydiffraction structure for [Nd{S2CN(C2H5)2}3PHEN] whereas, the crystal structure of[La{S2CN(C2H5)2}3PHEN] is considerably more complex. Our NMR and single-crystal X-raydiffraction results suggested polymorphism for bismuth di-n-butyldithiocarbamate complex.Finally, the experimental NMR results are complemented by chemical shifts obtained usingquantum chemical methods and verified the spectral assignments. Overall, our workdemonstrates how different experimental and theoretical methods can be combined that canafford insights into the solid-state structure and bonding environments of metal complexes.

  • 4.
    Gowda, Vasantha
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Experimental and Computational Magnetic Resonance Studies of Selected Rare Earth and Bismuth Complexes2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The rare-earth elements (REEs) and bismuth, being classified as the ‘most critical raw materials’ (European Raw Materials Initiatives, 2017), have a high economic importance to the EU combined with a high relative supply risk. REEs are highly important for the evolving technologies such as clean-energy applications, high-technology components, rechargeable batteries, permanent magnets, electric and hybrid vehicles, and phosphors monitors.This scientific research work aims at building a fundamental knowledge base concerning the electronic/molecular structure and properties of rare-earth element (REE) and bismuth complexes with dithiocarbamate (DTC) and 1,10-phenanthroline (PHEN) by employing state-of-the-art experimental techniques such as nuclear magnetic resonance (NMR) spectroscopy and X-ray diffraction (XRD) techniques together with ab initioquantum mechanical computational methods. This combination of methods has played a vital role in analysing the direct and significant effect of the heavy metal ions on the structural and magnetic resonance properties of the complexes, thereby, providing a framework of structure elucidation. This is of special importance for REEs, which are known to exhibit similar chemical and physical properties. The objectives of the work involve i) a systematic investigation of series of REE(III) as well as bismuth(III) complexes to get a profound understanding of the structure-properties relationship and ii) to find an appropriate theoretical modelling and NMR calculation methods, especially, for heavy metal systems in molecular and/or solid-state. This information can later be used in surface interaction studies of REE/bismuth minerals with DTC as well as in design and development of novel ligands for extraction/separation of metal ions.The REE(III) and bismuth(III) complexes with DTC and PHEN ligands have all provided aunique NMR fingerprint of the metal centre both in liquid and solid phase. The solid-state 13C and 15NNMR spectra of the diamagnetic REE(III) and bismuth(III) complexes were in accord with their structural data obtained by single crystal XRD. The density functional theory (DFT) methods were used to get complementary and refined structural and NMR parameters information for all diamagnetic complexes in the solid-state. The relativistic contributions due to scalar and spin-orbit correlations for the calculated 1H/13C/15N chemical shifts of REE complexes were analysed using two-component zeroth-order regular approximation (ZORA)/DFT while the ‘crystal-lattice’ effects on the NMR parameters were calculated by combining DFT calculations on molecular and periodic solid-state models. The paramagnetic REE complexes display huge differences in their 1H and 13C NMR spectral patterns. The experimental paramagnetic NMR (pNMR) chemical shifts, as well as the sizable difference of the 1H and 13C NMR shifts for these isoelectronic complexes, are well reproduced by the advanced calculations using ab initio/DFT approach. The accuracy of this approach is very promising for further applications to demanding pNMR problems involving paramagnetic f-block elements.The results presented in this thesis demonstrate that a multidisciplinary approach of combined experimental NMR and XRD techniques along with computational modelling and property calculations is highly efficient in studying molecular complexes and solids containing heavy metal systems, such as rare-earths and bismuth.

  • 5.
    Gowda, Vasantha
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Project: Solid-State NMR and DFT calculations on rare earth metal complexes2013Other (Other (popular science, discussion, etc.))
  • 6.
    Gowda, Vasantha
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Laitinen, Risto S.
    Laboratory of Inorganic Chemistry, University of Oulu.
    Telkki, Ville-Veikko
    NMR Research Unit, University of Oulu.
    Larsson, Anna-Carin
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Antzutkin, Oleg
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Lantto, Perttu
    NMR Research Unit, University of Oulu.
    DFT calculations in the assignment of solid-state NMR and crystal structure elucidation of a lanthanum(iii) complex with dithiocarbamate and phenanthroline2016In: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, Vol. 45, no 48, p. 19473-19484Article in journal (Refereed)
    Abstract [en]

    The molecular, crystal, and electronic structures as well as spectroscopic properties of a mononuclear heteroleptic lanthanum(iii) complex with diethyldithiocarbamate and 1,10-phenanthroline ligands (3 : 1) were studied by solid-state 13C and 15N cross-polarisation (CP) magic-angle-spinning (MAS) NMR, X-ray diffraction (XRD), and first principles density functional theory (DFT) calculations. A substantially different powder XRD pattern and 13C and 15N CP-MAS NMR spectra indicated that the title compound is not isostructural to the previously reported analogous rare earth complexes with the space group P21/n. Both 13C and 15N CP-MAS NMR revealed the presence of six structurally different dithiocarbamate groups in the asymmetric unit cell, implying a non-centrosymmetric packing arrangement of molecules. This was supported by single-crystal X-ray crystallography showing that the title compound crystallised in the triclinic space group P1[combining macron]. In addition, the crystal structure also revealed that one of the dithiocarbamate ligands has a conformational disorder. NMR chemical shift calculations employing the periodic gauge including projector augmented wave (GIPAW) approach supported the assignment of the experimental 13C and 15N NMR spectra. However, the best correspondences were obtained with the structure where the atomic positions in the X-ray unit cell were optimised at the DFT level. The roles of the scalar and spin-orbit relativistic effects on NMR shielding were investigated using the zeroth-order regular approximation (ZORA) method with the outcome that already the scalar relativistic level qualitatively reproduces the experimental chemical shifts. The electronic properties of the complex were evaluated based on the results of the natural bond orbital (NBO) and topology of the electron density analyses. Overall, we apply a multidisciplinary approach acquiring comprehensive information about the solid-state structure and the metal-ligand bonding of the heteroleptic lanthanum complex.

  • 7.
    Gowda, Vasantha
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Larsson, Anna-Carin
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Antzutkin, Oleg
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Lantto, P.
    University of Oulu.
    Telkki, V-V
    University of Oulu.
    Öberg, Sven
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mathematical Science.
    Structural investigations of rare earth dialkyl dithiocarbamate complexes: solid-state NMR, X-ray diffraction and DFT calculation studies2013Conference paper (Other academic)
    Abstract [en]

    In this study, we made an attempt to qualitatively study the structures of few rare earth metal complexes by employing solid state NMR, X-Ray Diffraction, and preliminary DFT calculations. High resolution 13C and 15N solid state CP/MAS NMR spectra were recorded for six diamagnetic polycrystalline rare earth dialkyldithiocarbamates of the general formula [(RE2S2CNR2)3 PHEN] (where RE=La or Y, R=C2H5, C3H7, and i-C3H7) [1]. Different isotropic 13C and 15N chemical shifts for the three dialkyldithiocarbamato groups were observed. Regulacio et al. (2005) inferred that irrespective of the alkyl chains, rare earth complexes of dialkyldithiocarbamates and phenanthroline (3:1) ligands always crystallize in a monoclinic system with a space P21/c group. However, comparative analysis of solid state 13C/15N CPMAS spectra of polycrystalline yttrium and lanthanum diethyldithiocarbamate complexes shows the presence of significant differences, indicating structural variations of these complexes. Also, quite different X-Ray diffraction powder pattern was observed for the above two complexes. Finally, the computational geometry optimization of Y and La complexes, followed by the preliminary calculation of 13C and 15N chemical shifts and shielding contributions with the ADF program [2], found to be very near to the experimental results.

  • 8.
    Gowda, Vasantha
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Larsson, Anna-Carin
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Antzutkin, Oleg
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Lantto, Perttu
    University of Oulu.
    Modelling and structrual optimizations of rare earth coordination: First principles calculations2013Conference paper (Other academic)
    Abstract [en]

    An approximate 3D structure for the yttrium diethyldithiocarbamato-phenanthroline complex 1, obtained by manually replacing the Nd3+ ion with Y3+ion of the reported crystal structure for neodymium diethyldithiocarbamato-phenanthroline complex 2 followed by DFT geometry optimization using periodic boundary conditions with dispersion corrected functional, has been compared with DFT optimized structure for 1. The quality of the method is discussed by comparing predicted PXRD pattern, high resolution solid state 13C and 15N CP/MAS NMR data and calculated chemical shift tensor eigenvalues for optimized structures for 1 and 2. We have observed an excellent agreement between the ‘modeled’ and experimental structures. Finally, to take into account the relativistic effects on NMR shielding calculations, we have employed the zeroth-order regular approximation (ZORA) formalism using Slater-type orbital (STO) basis sets implemented in Amsterdam Density Functional (ADF) package. The present approach can be further extended to study other complexes of rare earth metals in general, particularly those having similar crystal structure.

  • 9.
    Gowda, Vasantha
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering. NMR Research Unit, University of Oulu.
    Sarma, Bipul
    Department of Chemical Sciences, Tezpur University.
    Laitinen, Risto S.
    Laboratory of Inorganic Chemistry, University of Oulu.
    Larsson, Anna-Carin
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Ivanov, Alexander V.
    Institute of Geology and Nature Management, Far Eastern Branch of the Russian Academy of Sciences .
    Iuga, Dinu
    Department of Physics, Warwick University.
    Lantto, Perttu
    NMR Research Unit, University of Oulu.
    Antzutkin, Oleg
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering. Department of Physics, Warwick University.
    Structural insights into the polymorphism of bismuth(III) di-n-butyldithiocarbamate by X-ray diffraction, solid-state (13C/15N) CP-MAS NMR and DFT calculations2017In: Polyhedron, ISSN 0277-5387, E-ISSN 1873-3719, Vol. 129, p. 123-132Article in journal (Refereed)
    Abstract [en]

    Two crystalline polymorphs of a binuclear tris(di-n-butyldithiocarbamato)bismuth(III) complex, I and II, with an empirical formula of [Bi{S2CN(n-C4H9)2}3] were synthesised and characterised by X-ray diffraction (XRD), solid-state NMR and density functional theory (DFT) calculations. At the supramolecular level, these mononuclear molecular units interact in pairs via secondary Bi⋯S bonds, yielding binuclear formations of [Bi2{S2CN(n-C4H9)2}6]. The polymorph I () contains two isomeric non-centrosymmetric binuclear molecules of [Bi2{S2CN(n-C4H9)2}6], which are related to each other as conformers, therefore having four structurally inequivalent bismuth atoms and twelve inequivalent dithiocarbamate ligands. In contrast, the structurally simpler polymorph II (P21/n) exists as a single molecular form of the corresponding centrosymmetric binuclear formation, comprising two structurally equivalent bismuth atoms and three structurally different dithiocarbamate groups. The polymorphs I and II were found to be interconvertible by altering the solvent system during the recrystallisation process. Sun et al. (2012) has reported a crystalline form of the title compound which resembles, but is not identical with, polymorph II. Experimental solid-state 13C and 15N cross-polarisation (CP) magic-angle-spinning (MAS) NMR spectra of both polymorphs I and II were in accord with the direct structural data on these complexes. Assignments of the resonance lines in the solid-state 13C and 15N NMR spectra were assisted by chemical shift calculations of the crystals using periodic DFT.

  • 10.
    Gowda, Vasantha
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Sarma, Bipul
    Department of Chemical Sciences, Division of Chemical Engineering, Tezpur University, Tezpur, Assam.
    Öberg, Sven
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Telkki, Ville-Veikko
    University of Oulu, NMR Research Group, Division of Chemical Engineering, Faculty of Science, University of Oulu.
    Larsson, Anna-Carin
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Lantto, Perttu
    University of Oulu, NMR Research Group, Division of Chemical Engineering, Faculty of Science, University of Oulu.
    Antzutkin, Oleg
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Structure Elucidation of an Yttrium Diethyldithiocarbamato-Phenanthroline Complex by X-ray Crystallography, Solid-State NMR, and ab-initio Quantum Chemical Calculations2016In: European Journal of Inorganic Chemistry, ISSN 1434-1948, E-ISSN 1099-1948, Vol. 20, p. 3278-3291Article in journal (Refereed)
    Abstract [en]

    We present a structural analysis method for molecular and electronic structure of yttrium diethyldithiocarbamato-phenanthroline complex {[Y(S2CNR2)3PHEN] with R = C2H5 and PHEN = 1,10-phenanthroline} combining solid-state NMR spectroscopy, XRD, and first principles DFT calculations. Replacing the Nd3+ ion with Y3+ in the reported crystal structure of [Nd(S2CNR2)3PHEN] complex generated an approximate 3D structure of the title complex. The structure was then subjected to first principles quantum chemical geometry optimisation using periodic DFT method. The quality of the method is discussed by comparing predicted and experimental powder XRD patterns. Full assignment of 13C and 15N solid-state CP-MAS NMR spectra as well as analyses of the principal values of the chemical shift tensors were carried out using periodic scalar relativistic DFT modelling. Spin-orbit relativistic effects, estimated by SO-ZORA formalism for one molecular unit, were evaluated. Finally, the X-ray structure of the title complex was determined, which proved that the former procedure is appropriate. The most important orbital interactions were investigated by Natural Bond Orbital analysis. The isotropic shielding values for S2CN-carbons were analysed by Natural Localised Molecular Orbital analysis. The present approach can be further extended to study other rare earth metal complexes, particularly those having similar but not yet solved crystal structures

  • 11.
    Ivanov, Alexander V.
    et al.
    Institute of Geology and Nature Management, Far Eastern Branch of the Russian Academy of Sciences .
    Gerasimenko, A.V.
    Institute of Chemistry, Far Eastern Branch of the Russian Academy of Sciences.
    Egorova, I.V.
    Blagoveshchensk State Pedagogical University.
    Zaeva, A.S.
    Institute of Geology and Nature Management, Far East Branch, Russian Academy of Sciences.
    Novikova, E.V.
    Institute of Geology and Nature Management, Far East Branch, Russian Academy of Sciences.
    Rodionova, N.A.
    Blagoveshchensk State Pedagogical University.
    Gowda, V.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering. University of Oulu.
    Antzutkin, O.N.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering. Warwick University.
    Chemisorption Synthesis of the Ion-Polymeric Heteronuclear Gold(III)-Bismuth(III) Complex ([Au{S2CN(C3H7)2}2]3[Bi2Cl9])n Based on [Bi2{S2CN(C3H7)2}6]: 13C MAS NMR, Supramolecular Structure, and Thermal Behavior2018In: Russian journal of coordination chemistry, ISSN 1070-3284, E-ISSN 1608-3318, Vol. 44, no 8, p. 518-531Article in journal (Refereed)
    Abstract [en]

    Chemisorption synthesis on the basis of the binuclear compound [Bi2{S2CN(C3H7)2}6] (I) and preparative isolation of the ion-polymeric heteronuclear gold(III)-bismuth(III) complex ([Au{S2CN(C3H7)2}2]3[Bi2Cl9])n (II) are carried out. Compounds I and II are characterized in comparison by IR spectroscopy and 13C CP-MAS NMR. According to the X-ray diffraction analysis data (CIF file CCDC no. 1407705), the cationic moiety of compound II exhibits an unusually complicated supramolecular structure including six isomeric noncentrosymmetric complex cations [Au{S2CN(C3H7)2}2]+ (hereinafter A-F) and two binuclear anions [Bi2Cl9]3- as conformers. The isomeric gold(III) cations perform various structural functions. Owing to pair secondary interactions Au···S, cations B, C, E, and F form centrosymmetric ([E···E], [F···F]) and noncentrosymmetric ([B···C]) binuclear aggregates [Au2{S2CN(C3H7)2}4]2+, whereas cations A and D are not involved in dimerization. The strongest secondary Au···S bonds are formed between the binuclear and mononuclear cations, resulting in the formation of supramolecular cation-cationic polymer chains of two types: (⋅⋅⋅A⋅⋅⋅[B⋅⋅⋅C]⋅⋅⋅A⋅⋅⋅[B⋅⋅⋅C]⋅⋅⋅)n and (D⋅⋅⋅[E⋅⋅⋅E]⋅⋅⋅D⋅⋅⋅[F⋅⋅⋅F]⋅⋅⋅])n. In both chains, the gold atoms of the binuclear cations are characterized by a distorted octahedral coordination [S6], whereas in the mononuclear cations the gold atoms retain the square environment [S4]. The cation-anionic interactions are provided by secondary bonds Cl⋅⋅⋅S involving the terminal chlorine atoms of isomeric [Bi2Cl9]3- and the sulfur atoms of the binuclear cations [Au2{S2CN(C3H7)2}4]2+. The character of the thermal behavior of compounds I and II is studied by simultaneous thermal analysis with the identification of intermediate and final products of the thermal transformations. The thermolysis of compound I at 193-320°C is accompanied by the formation of Bi2S3 with an impurity of reduced metallic bismuth particles. The final products of the thermal transformations of compound II are reduced elemental gold and Bi2O3, and the thermal transformation intermediates are BiCl3 and Bi2S3.

  • 12.
    Viveka, Shivapura
    et al.
    Department of Studies in Chemistry, Mangalagangotri, Mangalore University, Konaje.
    Gowda, Vasantha
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Dinesha, Dinesha
    Department of Studies in Chemistry, Mangalagangotri, Mangalore University, Konaje.
    Naveen, Shivalingegowda
    Institution of Excellence, Vijnana Bhavana, Manasagangotri, University of Mysore.
    Lokanath, Neratur Krishnappagowda
    Department of Studies in Physics, Manasagangotri, University of Mysore.
    Nagaraja, Gundibasappa Karikannar
    Department of Studies in Chemistry, Mangalagangotri, Mangalore University, Konaje.
    Structural, spectral, and theoretical investigations of 5-methyl-1-phenyl-1H-pyrazole-4-carboxylic acid2016In: Research on chemical intermediates (Print), ISSN 0922-6168, E-ISSN 1568-5675, Vol. 42, no 5, p. 4497-4511Article in journal (Refereed)
    Abstract [en]

    The present research work has focused on combined experimental and theoretical studies of one of the biologically important pyrazole-4-carboxylic acid derivatives, viz. 5-methyl-1-phenyl-1H-pyrazole-4-carboxylic acid (C11H10N2O2). The starting material 5-methyl-1-phenyl-1H-4-pyrazolecarboxylate (1) was obtained by the cyclocondensation of ethyl acetoacetate, N,N-dimethylformamide dimethyl acetal (DMF-DMA), and phenylhydrazine, which upon basic hydrolysis yielded the corresponding acid (2). The target compound (2) was characterized by 1H and 13C NMR (solution in DMSO), Fourier transform infrared (FT-IR) spectroscopy, thermo gravimetric analysis, and by single-crystal X-ray diffraction technique. The single crystals of compound (2) were obtained at room temperature by slow evaporation of ethanol as solvent and crystallized in the space group P2 1/n of monoclinic system. The experimental FT-IR and 1H and 13C NMR chemical shifts have been compared to those calculated by means of density functional theory (DFT) at the B3LYP/TZ2P level of theory. The continuum-like screening model was used for geometry optimization of a single molecule and for subsequent calculations of NMR shielding constants in solution (DMSO). Finally, the HOMO–LUMO energy levels were also constructed to study the electronic transition within the molecule by time-dependent TD-DFT method.

  • 13.
    Viveka, Shivapura
    et al.
    Department of Studies in Chemistry, Mangalagangotri, Mangalore University, Konaje.
    Gowda, Vasantha
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Dinesha, Dinesha
    Department of Studies in Chemistry, Mangalagangotri, Mangalore University, Konaje.
    Naveen, Shivalingegowda
    Institution of Excellence, Vijnana Bhavana, Manasagangotri, University of Mysore.
    Lokanath, Neratur Krishnappagowda
    Department of Studies in Physics, Manasagangotri, University of Mysore.
    Nagaraja, Gundibasappa Karikannar
    Department of Studies in Chemistry, Mangalagangotri, Mangalore University, Konaje.
    Synthesis, characterization, single crystal X-ray diffraction and DFT studies of ethyl 5-methyl-1-phenyl-1H-pyrazole-4-carboxylate2016In: Molecular Crystals and Liquid Crystals, ISSN 1542-1406, E-ISSN 1563-5287, p. 135-145Article in journal (Refereed)
    Abstract [en]

    The present study describes the synthesis, spectroscopic, and single crystal X-ray structural analysis of ethyl 5-methyl-1-phenyl-1H-pyrazole-4-carboxylate. The pyrazole ester of formula [C13H14N2O2] was prepared from the three-component one-pot condensation reaction of ethyl acetoacetate, N,N-dimethyldimethoxymethanamine, and phenyl hydrazine. The product was crystallized by using ethanol as solvent. The structure of the compound was confirmed by elemental analysis, Fourier transforms infrared (IR), thermogravimetric analysis, UV-visible (UV-Vis), 1H NMR, and single-crystal X-ray diffraction studies. The gas-phase molecular geometry and the electronic structure-property of the molecule were calculated at the density functional theory. The frontier molecular orbitals, theoretical UV-Vis, and IR stretching vibrations were also reported. The compound crystallizes in the monoclinic system with the space group P21/c and Z = 4. The unit cell parameters are a = 12.141(3) Å, b = 13.934(4) Å, c = 7.2777(18) Å, and β = 97.816(14)0. The structure is stabilized by an intermolecular interaction of type C-H···O and the structure also involves C-H···π interactions

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