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'Mixed Valence' in keywords
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1Author    Takahiro Ueda, Nobuo NakamuraRequires cookie*
 Title    Sb NMR and SCF-MS-Xa Studies of Quadrupole Interaction and The Electronic Structure of Mixed-Valence Compound, Cs 2 SbCl 6  
 Abstract    Cs 2 SbCl 6 is known as a typical mixed-valence compound. It crystallizes into a tetragonal space group I4 1 /amd and contains two different complex anions, Sb(III)Cl| _ and Sb(V)Clg . The dark blue color of this compound has been considered to originate from a charge transfer between the above two anions. In order to study the electronic structure of these complex anions and the existence of charge transfer between them we measured the 121 Sb NMR spectrum and carried out molecular orbital calculations on the electronic states of these anions. The 121 Sb NMR spectrum consists of two peaks at 0 and 30 kHz which can be assigned to the central transition of l21 Sb in Sb(V)Cl<~ and Sb(III)Cl| _ , respectively. The line shape analyses of the spectra led to nuclear quadrupole coupling constants of nearly zero for Sb(V)Cl7 and 4.9 ±0.5 MHz for Sb(III)Cl| at room temperature. The quadrupole coupling constant of 1 Sb(III) decreases steadily on heating. The calculations of the electronic ground state energies of both anions were calculated by the MS-Xa molecular orbital method. The calculated charge-transfer band from the A lg state of Sb(III)Clg" to the A lg state of Sb(V)Cl6 appears at 610 nm and can account for the experimental electronic spectrum, the calculated quadrupole coupling constant in Sb(III)Clg" however is far larger than the experimental one. The contribution of the charge-transferred state to the ground state is negligible and so the temperature dependence of the quadrupole coupling constant of 121 Sb(III) is attributed to an anisotropic thermal expansion of the compound. 
  Reference    Z. Naturforsch. 51a, 672—676 (1996); received October 10 1995 
  Published    1996 
  Keywords    NMR, Quadrupole interaction, Molecular orbital, Mixed valence 
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 TEI-XML for    default:Reihe_A/51/ZNA-1996-51a-0672.pdf 
 Identifier    ZNA-1996-51a-0672 
 Volume    51 
2Author    K. D. Buse, H. J. Keller, D. NötheRequires cookie*
 Title    Pt(NH3)2(SCN)2J: Ein Platinkomplex mit gemischter Wertigkeit Pt(NH3)2(SCN)2I: A Mixed Valence Platinum Compound  
 Abstract    Pt(NH3)2(SCN)2 dissolved in liquid SO2 reacts with molecular iodine to yield a green lustrous solid of stoichiometry Pt(NH3)2(SCN)2I. The compound is diamagnetic in the solid state and in solution and has to be taken for a platinum(II, IV) mixed valence compound, therefore. Chemical and physical evidence so far suggest a linear chain solid with either iodide-bridged metal complex chains or metal complex stacks with parallel triiodide chains. 
  Reference    (Z. Naturforsch. 31b, 194—197 [1976]; eingegangen am 13. Oktober 1975) 
  Published    1976 
  Keywords    Metal Complexes, Mixed Valence, Linear Chain Complexes, Platinum 
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 TEI-XML for    default:Reihe_B/31/ZNB-1976-31b-0194.pdf 
 Identifier    ZNB-1976-31b-0194 
 Volume    31 
3Author    G. C. Papavassiliou, D. LayekRequires cookie*
 Title    Electronic and Resonance Raman Spectra of Some New Mixed-Valence Compounds of Pt and Pd with a Metal-Halide Chain  
 Abstract    The electronic and resonance Raman spectra of new mixed-valence compounds of the type M2'[M(L)X3][M(L)X5], where M' = K, NH4, M -Pt or Pd, L = NH3 or pyridine, and X = Cl, Br or I, have been studied. The single-crystal polarized reflectance spectra indicate the one-dimensional semiconductor behaviour. The polarized resonance Raman spectra confirm the —M(II)—X-M(IV)-X linear chain structure, which is in accordance with the X-ray results. The polarization of M-N bands can be explained by the Snyder's theory (1971). 
  Reference    Z. Naturforsch. 35b, 676—679 (1980); received January 14 1980 
  Published    1980 
  Keywords    Electronic Spectra, Raman Spectra, Mixed-Valence, Oriented Molecules 
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 TEI-XML for    default:Reihe_B/35/ZNB-1980-35b-0676.pdf 
 Identifier    ZNB-1980-35b-0676 
 Volume    35 
4Author    RobinJ H Clark, Mohamedally Kurmoo, K. D. Buse, H. J. KellerRequires cookie*
 Title    Electronic and Resonance Raman Spectra of the Linear Chain Mixed Valence Compound Pt(NH3)2(SCN)2I  
 Abstract    The partially oxidized cis-Pt(NH3)2(SCN)2I has been studied by resonance Raman spectroscopy. A progression in the symmetric I-Pt IV -I vibration (J>I = 120.1 cm -1), reaching as far as 8 v±, has been observed. The compound Pt(NH3)2(SCN)2I could be identified as a mixed valence solid with neutral, linear Pt n -"I-Pt IV chains. 
  Reference    Z. Naturforsch. 35b, 1272—1273 (1980); received May 2 1980 
  Published    1980 
  Keywords    Mixed Valence, Linear Chain Platinum Complex, Wolffram's Salt Analogue 
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 TEI-XML for    default:Reihe_B/35/ZNB-1980-35b-1272.pdf 
 Identifier    ZNB-1980-35b-1272 
 Volume    35 
5Author    Wolfgang Jeitschko, HorstA. Mons, Ute Ch, ManfredH. Rodewald, MöllerRequires cookie*
 Title    The Crystal Structure of the Potential Ferroelectric Calcium Rhenate(VI, VII) CanRe4 0 24 and its Relation to the Structure of S rn 0 s40 24  
 Abstract    The title compound was prepared in well-crystallized form by thermal decomposition of Ca5Re20i2. Its structure was determined from single-crystal X-ray diffractometer data: /4 j, a = 1107.0(1), c = 1609.3(1) pm, Z = 4, R -0.056 for 4565 structure factors and 119 variable parameters. The calcium atoms occupy seven different sites with 8, 9, or 10 oxygen neighbors. The two different rhenium atoms are octahedrally coordinated by oxygen atoms with average Re-O distances of 193.1 and 187.7 pm for the six-and seven-valent rhenium atoms, respectively. The compound shows Curie-Weiss behavior with a magnetic moment of n exp = 1.15(±0.10) Pb per Re(VI) atom. The structure is closely related to that of Srn0s4024 which, however, crystallizes in the space group I2la. The difference between the two structures arises through the higher coordination numbers of the strontium atoms. It is suggested that at high temperature both compounds crystallize in the common higher symmetry space group I4\/a. Since CanRe4024 crystallizes in the pyroelectric class 4 this compound is expected to be ferroelectric. 
  Reference    (Z. Naturforsch. 53b, 31—36 [1998]; received October 17 1997) 
  Published    1998 
  Keywords    Crystal Structure, Ferroelectrics, Mixed Valence, Rhenates, Perrhenates 
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 TEI-XML for    default:Reihe_B/53/ZNB-1998-53b-0031.pdf 
 Identifier    ZNB-1998-53b-0031 
 Volume    53 
6Author    Wolfgang Jeitschko, HorstA. Mons, Ute Ch, RodewaldRequires cookie*
 Title    Preparation and Crystal Structure of the Calcium Rhenate(VI, VII) Ca5Re30 15.x  
 Abstract    The title compound was prepared by reaction of elemental calcium with the calcium metaper-rhenate Ca(ReC>4)2. Its crystal structure was determined from single-crystal X-ray data: Amm2, a = 560.31 (5)pm, b = 1572.4(1)pm, c = 719.91 (6)pm ,Z = 2 ,R = 0.033 for 930 structure factors and 46 variable parameters. The calcium atoms occupy three atomic sites, all with seven oxygen neighbors. Of the two different rhenium atoms one has square-pyramidal oxygen coordination with an average oxidation number +6.25. The other rhenium site (oxidation number +7) was refined as a split position with trigonal-bipyramidal (75%) and tetrahedral oxygen coordination (25%). One oxygen site remains unoccupied, whenever the tetrahedral rhenium site is occupied, resulting in the composition Ca5Re3 0 i4.75. A test for superconductivity of this black compound down to 1.5 K was negative. 
  Reference    Z. Naturforsch. 54b, 1483—1488 (1999); received August 16 1999 
  Published    1999 
  Keywords    Crystal Structure, Mixed Valence, Rhenates, Perrhenates 
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 TEI-XML for    default:Reihe_B/54/ZNB-1999-54b-1483.pdf 
 Identifier    ZNB-1999-54b-1483 
 Volume    54 
7Author    Florian Stadler, Thomas Fickenscher, Rainer PöttgenRequires cookie*
 Title    Synthesis and Structure of RE2Rh2Cd (RE = La, Ce, Pr, Nd, Sm)  
 Abstract    New intermetallic cadmium compounds /?£2Rh2Cd (r e = La, Ce, Pr, Nd, Sm) were syn­ thesized from the elements in sealed tantalum tubes in a high-frequency furnace. They were characterized through X-ray powder data: Mo2FeB2 type, space group P4/mbm, Z = 2. Single crystal data of the cerium compound (a = 762.8(1), c = 377.8(1) pm, wR2 = 0.0662, 199 F2 values, and 13 variable parameters) revealed small defects on the rhodium position leading to the composition Ce2R h186(3)Cd for the investi­ gated crystal. According to the course of the cell volumes Ce2Rh2Cd may be classified as a mixed-valent compound. The Ce2Rh2Cd structure is an intergrowth of slightly distorted A1B2 and CsCl related slabs of compositions CeRh2 and CeCd. Within the CeRh2 slab short Ce-Rh contacts (284-300 pm) are indicative of strong Ce-Rh bonding. The Rh-Rh distance within the A1B2 re­ lated slab is 289 pm. 
  Reference    Z. Naturforsch. 56b, 1241—1244 (2001); received September 10 2001 
  Published    2001 
  Keywords    Cadmium, Solid State Synthesis, Mixed Valence 
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 TEI-XML for    default:Reihe_B/56/ZNB-2001-56b-1241_n.pdf 
 Identifier    ZNB-2001-56b-1241_n 
 Volume    56