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  • 1. Abbasi, Alireza
    et al.
    Damian Risberg, Emiliana
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för fysikalisk kemi, oorganisk kemi och strukturkemi.
    Eriksson, Lars
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Mink, Janos
    Persson, Ingmar
    Sandström, Magnus
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Sidorov, Yurii V.
    Skripkin, Mikhail Yu.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Ullström, Ann-Sofi
    Crystallographic and Vibrational Spectroscopic Studies of Octakis(dimethyl sulfoxide)lanthanoid(III) Iodides2007Inngår i: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 46, nr 19, s. 7731-7741Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The octakis(DMSO) (DMSO = dimethylsulfoxide) neodymium(III), samarium(III), gadolinium(III), dysprosium(III), erbium(III), and lutetium(III) iodides crystallize in the monoclinic space group P21/n (No. 14) with Z = 4, while the octakis(DMSO) iodides of the larger lanthanum(III), cerium(III), and praseodymium(III) ions crystallize in the orthorhombic space group Pbca (No. 61), Z = 8. In all [Ln(OS(Me2)8]I3 compounds the lanthanoid(III) ions coordinate eight DMSO oxygen atoms in a distorted square antiprism. Up to three of the DMSO ligands were found to be disordered and were described by two alternative configurations related by a twist around the metal−oxygen (Ln−O) bond. To resolve the atomic positions and achieve reliable Ln−O bond distances, complete semirigid DMSO molecules with restrained geometry and partial occupancy were refined for the alternative sites. This disorder model was also applied on previously collected data for the monoclinic octakis(DMSO)yttrium(III) iodide. At ambient temperature, the eight Ln−O bond distances are distributed over a range of about 0.1 Å. The average value increases from Ln−O 2.30, 2.34, 2.34, 2.36, 2.38, 2.40 to 2.43 Å (Ln = Lu, Er, Y, Dy, Gd, Sm, and Nd) for the monoclinic [Ln(OSMe2)8]I3 structures, and from 2.44, 2.47 to 2.49 Å (Ln = Pr, Ce, and La) for the orthorhombic structures, respectively. The average of the La−O and Nd−O bond distances remained unchanged at 100 K, 2.49 and 2.43 Å, respectively. Despite longer bond distances and larger Ln−O−S angles, the cell volumes are smaller for the orthorhombic structures (Ln = Pr, Ce, and La) than for the monoclinic structure with Ln = Nd, showing a more efficient packing arrangement. Raman and IR absorption spectra for the [Ln(OS(CH3)2)8]I3 (Ln = La, Ce, Pr, Nd, Gd, Tb, Dy, Er, Lu, and Y) compounds, also deuterated for La and Y, have been recorded and analyzed by means of normal coordinate methods. The force constants for the Ln−O and S−O stretching modes in the complexes increase with decreasing Ln−O bond distance and show increasing polarization of the bonds for the smaller and heavier lanthanoid(III) ions.

  • 2. Fischer, Christian E.
    et al.
    Mink, Janos
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Hajba, Laszlo
    Bacsik, Zoltan
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för materialkemi.
    Nemeth, Csaba
    Mihaly, Judith
    Raith, Alexander
    Cokoja, Mirza
    Kuehn, Fritz E.
    Vibrational spectroscopic study of SiO2-based nanotubes2013Inngår i: Vibrational Spectroscopy, ISSN 0924-2031, E-ISSN 1873-3697, Vol. 66, s. 104-118Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Novel organic-inorganic hybrid nanotubes containing silica and ethane (EtSNT), ethylene (ESNT) and acetylene (ASNT) units, as well as brominated ESNT (Br-ESNT) and glycine-modified Br-ESNT (Gly-ESNT) have been studied by IR and Raman spectroscopy. The results are compared with the spectral features for conventional silica nanotubes (SNT) and amorphous silica. Bands peculiar to organic moieties have been detected and assigned. Assignment of the silicate backbone vibrations was based on the results of normal coordinate calculations. Furthermore, characteristic silicate, so-called 'nanotube' vibrations have been identified and their band positions have been summarized to serve as a future reference for such compounds. SiOSi antisymmetric stretchings were observed in the range 1000-1110 cm(-1), while the symmetric stretchings appeared between 760 and 960 cm(-1) for EtSNT, ESNT and Br-ESNT. Force constants have been refined for models of the repeating structure units: O3SiOSi(OSi)(3) for SNT and SiCHnCHnSi(OSi)(3) for organosilica nanotubes (n = 2, EtSNT: n = 1, ESNT and n = 0, ASNT). The calculated SiO stretching force constants were increased from 4.79 to 4.88 and 5.11 N cm(-1) for EtSNT, ESNT and ASNT, respectively. The force constants have been compared with those for several silicates and SiO bond length are predicted and discussed.

  • 3. Kocsis, L.
    et al.
    Mink, Janos
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för fysikalisk kemi, oorganisk kemi och strukturkemi, Avdelningen för oorganisk kemi.
    Jalilehvand, F.
    Laffin, L. J.
    Berkesi, O.
    Hajba, L.
    Vibrational spectroscopic study of the hydrated platinum(II), palladium(II) and cis-diammineplatinum(II) ions in acidic aqueous solutions2009Inngår i: Journal of Raman Spectroscopy, ISSN 0377-0486, E-ISSN 1097-4555, Vol. 40, nr 5, s. 481-490Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Mid infrared, far-infrared and Raman spectroscopic studies, combined with force field analyses, were performed for the 1 hydrated platinum(II) and palladium(II) ions and cis-diammineplatinum(II) complex in acidic aqueous solutions. Simplified Density Functional Theory (DFT) calculations were made for the equatorial plane of the platinum complexes. Careful subtraction of solvent spectra allowed a number of 'internal' modes of coordinated H2O and NH3 to be determined as weak residual bands. The [Pt(OH2)(6)](2+) and [cis-Pt(NH3)(2)(OH2)(4)](2+) complexes were found to be six-coordinated with four ligands strongly bound in an equatorial plane. The assignments of the vibrational modes in the equatorial plane could be performed on the basis of the experimental observations and by comparison with metal-ligand vibrations of square-planar complexes, aided by normal coordinate calculations. For the weakly coordinated axial aqua ligands, the low wavenumber range and the polarizibility properties allowed the assignments of the bands at about 365 and 325 cm(-1) to the stretching modes of one short and one longer Pt - O* bound to axial aqua ligands, respectively. A similar picture with even less strongly bound axial water molecules emerges from Raman spectroscopy data for the hydrated palladium(II) ion, [Pd(OH2)(6)](2+). The results are consistent with a description of the [Pt(OH2)(6)](2+) and [Pd(OH2)(6)](2+) aqua ions in C-4v symmetry, and with the [cis-Pt(NH3)(2)(OH2)(4)](2+) complex in the Cs point group, and also in qualitative agreement with the structures devised from previous extended X-ray absorption fine structure (EXAFS) measurements.

  • 4.
    Mink, Janos
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Skripkin, Mikhail
    Hajba, L
    Németh, C
    Abbasi, Alireza
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för fysikalisk kemi, oorganisk kemi och strukturkemi.
    Sandström, Magnus
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Infrared and raman spectroscopic and theoretical studies of nonaaqua complexes of trivalent rare earth metal ions2005Inngår i: Spectrochimica Acta Part A - Molecular and Biomolecular Spectroscopy, ISSN 1386-1425, E-ISSN 1873-3557, Vol. 61, nr 7, s. 1639-1645Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Infrared (IR), far-infrared (far-IR) and Raman spectra have been recorded of the hydrated lanthanide(III) trifluoromethanesulfonates, [Ln(OH2)9](CF3SO3)3, (Ln = La, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu), and also for the deuterated [La(OD2)9](CF3SO3)3 compound. This has enabled complete assignments of all seven metal–oxygen stretching modes for the first time. Force constant calculations have been performed for an LnO93+ moiety, with a tricapped trigonal prismatic oxygen atom arrangement in D3h point group symmetry.

    The lanthanide contraction in reflected in continuously increasing trends for the averaged LnO stretching frequencies and force constants with increasing inverse of ionic radii. The stretching force constants increased from 0.81 to 1.16 Ncm−1 for the LnO6 prism in the series from La to Lu, while those for the capping LnO3 bonds increased from 0.49 to 0.65 Ncm−1. The LnO stretching force constants showed a smooth correlation with the LnO bond distances to the prism oxygen atoms, while the correlation to the LnO capping oxygen atoms has a different shape, reflecting the increased ligand–ligand repulsion with decreasing lanthanide ion size.

  • 5.
    Risberg, Emiliana, Damian
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för fysikalisk kemi, oorganisk kemi och strukturkemi.
    Eriksson, Lars
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Mink, Janos
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Pettersson, Lars G. M.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Skripkin, Mikhail Yu.
    Sandström, Magnus
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Sulfur X-ray absorption and vibrational spectroscopic study of sulfite, sulfur dioxide and sulfonate solutions, and of the substituted sulfonate ions X3CSO3- (X = H, Cl, F)2007Inngår i: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 46, nr 20, s. 8332-8348Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Sulfur K-edge X-ray absorption near-edge structure (XANES) spectra have been recorded and the S(1s) electron excitations evaluated by means of density functional theory−transition potential (DFT−TP) calculations to provide insight into the coordination, bonding, and electronic structure. The XANES spectra for the various species in sulfur dioxide and aqueous sodium sulfite solutions show considerable differences at different pH values in the environmentally important sulfite(IV) system. In strongly acidic (pH < 1) aqueous sulfite solution the XANES spectra confirm that the hydrated sulfur dioxide molecule, SO2(aq), dominates. The theoretical spectra are consistent with an OSO angle of 119° in gas phase and acetonitrile solution, while in aqueous solution hydrogen bonding reduces the angle to 116°. The hydration affects the XANES spectra also for the sulfite ion, SO32-. At intermediate pH (4) the two coordination isomers, the sulfonate (HSO3-) and hydrogen sulfite (SO3H-) ions with the hydrogen atom coordinated to sulfur and oxygen, respectively, could be distinguished with the ratio HSO3-:SO3H- about 0.28:0.72 at 298 K. The relative amount of HSO3- increased with increasing temperature in the investigated range from 275 to 343 K. XANES spectra of sulfonate, methanesulfonate, trichloromethanesulfonate, and trifluoromethanesulfonate compounds, all with closely similar S−O bond distances in tetrahedral configuration around the sulfur atom, were interpreted by DFT−TP computations. The energy of their main electronic transition from the sulfur K-shell is about 2478 eV. The additional absorption features are similar when a hydrogen atom or an electron-donating methyl group is bonded to the −SO3 group. Significant changes occur for the electronegative trichloromethyl (Cl3C−) and trifluoromethyl (F3C−) groups, which strongly affect the distribution especially of the π electrons around the sulfur atom. The S−D bond distance 1.38(2) Å was obtained for the deuterated sulfonate (DSO3-) ion by Rietveld analysis of neutron powder diffraction data of CsDSO3. Raman and infrared absorption spectra of the CsHSO3, CsDSO3, H3CSO3Na, and Cl3CSO3Na·H2O compounds and Raman spectra of the sulfite solutions have been interpreted by normal coordinate calculations. The C−S stretching force constant for the trichloromethanesulfonate ion obtains an anomalously low value due to steric repulsion between the Cl3C− and −SO3 groups. The S−O stretching force constants were correlated with corresponding S−O bond distances for several oxosulfur species.

  • 6. Risberg, Emiliana Damian
    et al.
    Mink, János
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för fysikalisk kemi, oorganisk kemi och strukturkemi.
    Abbasi, Alireza
    Skripkin, Mikhail Yu.
    Hajba, Laszló
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för fysikalisk kemi, oorganisk kemi och strukturkemi.
    Lindqvist-Reis, Patric
    Bencze, Éva
    Sandström, Magnus
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för fysikalisk kemi, oorganisk kemi och strukturkemi.
    Ambidentate coordination in hydrogen bonded dimethyl sulfoxide, (CH3)2SO H3O+, and in dichlorobis(dimethyl sulfoxide) palladium(II) and platinum(II) solid solvates, by vibrational and sulfur K-edge X-ray absorption spectroscopy2009Inngår i: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, s. 1328-1339Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

     

    The strongly hydrogen bonded species (CH3)2SOH3O+ formed in concentrated hydrochloric acid displays a new low energy feature in its sulfur K-edge X-ray absorption near edge structure (XANES) spectrum. Density Functional Theory-Transition Potential (DFT-TP) calculations reveal that the strong hydrogen bonding decreases the energy of the transition S(1s) → LUMO, which has antibonding σ*(S–O) character, with about 0.8 eV. Normal coordinate force field analyses of the vibrational spectra show that the SO stretching force constant decreases from 4.72 N cm−1 in neat liquid dimethyl sulfoxide to 3.73 N cm−1 for the hydrogen bonded (CH3)2SOH3O+ species. The effects of sulfur coordination on the ambidentate dimethyl sulfoxide molecule were investigated for the trans-Pd((CH3)2SO)2Cl2, trans-Pd((CD3)2SO)2Cl2 and cis-Pt((CH3)2SO)2Cl2 complexes with square planar coordination of the chlorine and sulfur atoms. The XANES spectra again showed shifts toward low energy for the transition S(1 s) → LUMO, now with antibonding σ*(M–Cl, M–S) character, with a larger shift for M = Pt than Pd. DFT-TP calculations indicated that the differences between the XANES spectra of the geometrical cis and trans isomers of the M((CH3)2SO)2Cl2 complexes are expected to be too small to allow experimental distinction. The vibrational spectra of the palladium(II) and platinum(II) complexes were recorded and complete assignments of the fundamentals were achieved. Even though the M–S bond distances are quite similar the high covalency especially of the Pt–S bonds induces significant increases in the S–O stretching force constants, 6.79 and 7.18 N cm−1, respectively.

  • 7.
    Sandström, Magnus
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Mink, János
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Papai, Imre
    Chemical Research Center of the Hungarian Academy of Sciences, P.O. Box 77, H-1525, Budapest, Hungary.
    Skripkin, Mikhail
    Department of Chemistry, St. Petersburg State University, Universitetski pr., 26, 198504 St. Petersburg, Russia.
    Hajba, László
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Mihály, Judith
    Chemical Research Center of the Hungarian Academy of Sciences, Budapest.
    Neméth, Csaba
    Chemical Research Center of the Hungarian Academy of Sciences, Budapest.
    Vibrational spectroscopic and theoretical studies of urea derivatives with biochemical interest: N,N’-dimethylurea, N,N,N’,N’-tetramethylurea and N,N’-dimethylpropyleneurea2010Inngår i: Applied spectroscopy reviews (Softcover ed.), ISSN 0570-4928, E-ISSN 1520-569X, Vol. 45, s. 274-326Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Mid-infrared, far-infrared and Raman vibrational spectroscopic studies were combined with DFT calculations and normal coordinate force field analyses for N,N’-dimethylurea (DMU), N,N,N’,N’-tetramethylurea (TMU) and N,N'-dimethylpropyleneurea (DMPU, IUPAC name 1,3-dimethyltetrahydropyrimidin-2(1H)-one). The equilibrium molecular geometry of DMU (all three conformers), TMU and DMPU, and the frequencies, intensities and depolarization ratios of their fundamental IR and Raman vibrational transitions were obtained by DFT calculations. The vibrational spectra were fully analysed by normal coordinate methods as well. A starting force field for DMPU was obtained by adapting corresponding force constants for DMU and TMU, resulting after refinements in the stretching force constants: C=O (7.69, 7.30, 7.68 N×cm -1), C-N (5.16, 5.55, 5.05 N×cm -1) and C-Me (5.93, 4.00, 4.22 N×cm-1) for DMU, TMU and DMPU, respectively. The dominating conformer of liquid DMU was identified as trans-trans, strong intermolecular hydrogen bonding was verified in solid DMU, and weak dipole-dipole association was found in liquid TMU and in DMPU. Special attention was paid to analysing the methyl group frequencies, which revealed deviations from local C3v symmetry. A linear correlation was found between the CH stretching force constants and the inverse of the CH bond lengths (1/r2). The averaged NH stretching frequencies of gaseous, dissolved and solid urea and of DMU, with variations for hydrogen bonding of different strength, are linearly correlated to the NH stretching force constants. Characteristic skeletal vibrations were assigned for a broad variety of urea derivatives and also for pyrimidine derivatives, which all contain the N2C=O entity. The very strong IR bands of C=O stretching (1676 ± 40 cm-1) and asymmetric CN2 stretching (1478 ± 60 cm-1), and the very intense Raman feature of symmetric CN2 stretching or ring breathing (757 ± 80 cm-1), can be recognized as fingerprint bands also for the pyrimidine derivatives cytosine, thymine and uracil, which all are nucleobases in DNA and RNA nucleotides.

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