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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical chemistry accounts 63 (1983), S. 395-399 
    ISSN: 1432-2234
    Keywords: Ab initio-MO ; transition metal compound ; ethylene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Nickel(0)-olefine π-complexes such as Ni(C2H4)3 and Ni(C2H4)(PR3)2 [6] prepared by conventional ligand replacement reaction are diamagnetic and stable up to room temperature. Similar π-complexes e.g. Ni(C2H4) n (withn = 1, 2 or 3) generated by cryo-condensation technique [3] may exist in a paramagnetic state which derives from the triplet ground state of the atomic nickel. The stability of (η2-ethylene) nickel has been explained byab initio-MO calculations relating the energies of the complexes to different terms (1 S and3 F) of the nickel atom.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical chemistry accounts 63 (1983), S. 395-399 
    ISSN: 1432-2234
    Keywords: Ab initio-MO ; transition metal compound ; ethylene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Nickel(0)-olefine π-complexes such as Ni(C2H4)3 and Ni(C2H4)(PR3)2 [6] prepared by conventional ligand replacement reaction are diamagnetic and stable up to room temperature. Similar π-complexes e.g. Ni(C2H4) n (withn = 1, 2 or 3) generated by cryo-condensation technique [3] may exist in a paramagnetic state which derives from the triplet ground state of the atomic nickel. The stability of (η2-ethylene) nickel has been explained byab initio-MO calculations relating the energies of the complexes to different terms (1 S and3 F) of the nickel atom.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 56 (1995), S. 575-587 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The π-allylic organonickel compounds are considered to be key structures in the catalytic reactions of butadiene. Bis(η3-allyl)nickel, bis(η3-methallyl)nickel, and the syn-crotyl-cyclooctadiene-nickel cation have been calculated with DZ and TZ basis sets in all-electron and pseudopotential (ECP) Hartree-Fock (HF) methods and compared with experimental structures. In the second part, we report a systematic investigation of these compounds by density functional theory (DFT). The DFT-optimized structures are generally in better agreement with experimental data than are the HF results. © 1995 John Wiley & Sons, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0044-2313
    Keywords: Platinum complex ; crown ether ; Raman and IR data ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthese und Charakterisierung von cis- und trans-Tetrachlorobis(pyridin)platin(IV)[Na(15-cr-5)]2[PtCl6] · 2 H2O reagiert mit Pyridin in Wasser als Lösungsmittel zu cis-[PtCl4(py)2] (1) und in MeCN, DMF sowie in CH2Cl2 zu trans-[PtCl4(py)2] (2). Die Substitutionsreaktion wird durch Bestrahlung mit sichtbarem Licht beschleunigt. Sowohl gelöst in DMSO, DMF und MeCN als auch bei 503 K im festen Zustand isomerisiert 1 zu 2.1 und 2 sind umfassend IR- und ramanspektroskopisch charakterisiert worden. Die Molekülstruktur des trans-Isomeren 2 wurde auch durch Röntgeneinkristallstrukturunterschung ermittelt (monoklin, C2/m, a = 14.143(5), b = 7.171(3), c = 7.199(3) Å, β = 116.42(4)°, Z = 2, R1 = 0.0331, wR2 = 0.0727). 2 weist angenähert D2h Symmetrie auf, wobei die beiden trans-ständigen Pyridinliganden in einer Ebene liegen. Nach quantenchemischen Berechnungen ist 2 (D2h-Symmetrie) um 48.28 kJ/mol stabiler als 1 (C2v-Symmetrie).
    Notes: [Na(15-cr-5)]2[PtCl6] · 2 H2O reacts with pyridine in water as solvent to give cis-[PtCl4(py)2] (1) and in MeCN, DMF or in CH2Cl2 to give trans-[PtCl4(py)2] (2). The substitution reaction can be accelerated by irradiation with visible light. 1 isomerizes to give 2 in DMSO, DMF and MeCN as well as in solid state at 503 K.1 and 2 were thoroughly characterized IR and Raman spectroscopically. The molecular structure of the trans isomer 2 was also established by X-ray structure analysis (monoclinic, C2/m, a = 14.143(5), b = 7.171(3), c = 7.199(3) Å, β = 116.42(4)°, Z = 2, R1 = 0.0331, wR2 = 0.0727). 2 has nearly D2h symmetry with two trans standing pyridine ligands lying in a plane. According to quantum chemical calculations, 2 (D2h symmetry) is more stable (48.28 kJ/mol) than 1 (C2v symmetry).
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 69 (1998), S. 387-396 
    ISSN: 0020-7608
    Keywords: ab initio ; DFT ; CCSD(T) ; transition metal olefin complexes ; catalysis ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The structure of ethylene, allyl, and butadiene π-complexes with Ni0 and Ni2+ were optimized with density functional theory (DFT). The different kinds of coordinative interaction between the olefins and the metal had been discussed for the frontier orbitals of the given symmetry. Both components of the donation and back-donation bond were characterized by charge density analysis (CDA) and natural bond orbital (NBO) populations. In case of the butadiene ligand the s-cis and s-trans conformer and the transition state of their rearrangement were localized and characterized by their vibrational spectra. The calculated ionization of bis(π-allyl)nickel can be well represented by comparing the DFT energies of the neutral molecule and its cationic configurations (ΔSCF procedure).   © 1998 John Wiley & Sons, Inc. Int J Quant Chem 69: 387-396, 1998
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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