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  • Density functional calculations  (2)
  • Lithiation  (1)
  • Main-group elements  (1)
  • 1
    Electronic Resource
    Electronic Resource
    1,2 and 1,6 Additions of Lithium Reagents to γ-Methylenepyran Fischer-Type Carbene Complexes; Evolution of the 1,2 and 1,6 Adducts to Unsaturated Carbene Complexes Indirectly Stabilized by a Heteroatom, and to Pyranylidene Carbene Complexes (2000)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 577-581 
    Details
    ISSN: 1434-193X
    Keywords: Methylenepyran carbene complexes ; Lithiation ; Carbene complexes ; Tungsten ; Carbenes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---1,2 and 1,6 additions of lithium reagents to γ-methylenepyran Fischer-type carbene complexes are described. The 1,2 adducts obtained from alkynyllithium addition evolve by a 1,3 shift of the W(CO)5 fragment to give allenyltungsten carbonyl intermediates. Reaction with degassed water affords unsaturated carbene complexes indirectly stabilized by a heteroatom. The 1,6 anionic addition products are quenched by H2O at low temperature to give α,δ-unsaturated carbene complexes. On warming, an evolution occurs leading to new pyranylidene carbene complexes.Supporting information for this article is available on the WWW under //http://www.wiley-vch.de/contents/jc_2046/2000/099150_s.pdf or from the author.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 2
    Electronic Resource
    Electronic Resource
    The Distorted Pd9(μ:η5,η2-As2)4(PPh3)8 Architecture (1999)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1999 (1999), S. 673-678 
    Details
    ISSN: 1434-1948
    Keywords: Electron counting ; Electronic structure ; Density functional calculations ; Extended Hückel calculations ; Cluster compounds ; Cluster compounds ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Extended Hückel and density functional calculations were carried out on the title compound 1. Results indicate that the bonding of the interstitial Pdi atom with the D2d distorted (Pds)8(As2)4 cubic host differs from that found in the related metal-centered cubic species M9(μ4-E)6L8. Species 1 can be described as an approximate square-planar 16-electron PdiL4 center bound through Pdi-As rather than Pdi-Pds contacts to a distorted cubic fragment composed of four 30-electron bimetallic Pd2L8 units. Although a substantial gap is computed between the highest occupied molecular orbital and the lowest unoccupied molecular orbital for the observed electron count of 130 MVEs, calculations indicate that such an architecture should be observed for different electron counts close to that count. The incorporation of the central Pd atom does not seem to be essential to ensure the stability of the distorded Pd8(As2)4(PH3)8 cluster. Such empty clusters, with formally four M-M bonds and eight planar 16-electron Pds centers, should exist for electron counts close to 120 MVEs.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 3
    Electronic Resource
    Electronic Resource
    M8(μ8-E′)(μ4-E)6L8 Species Centered and Hexacapped by Main-Group Atoms (1999)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1999 (1999), S. 1161-1168 
    Details
    ISSN: 1434-1948
    Keywords: Electron count ; Electronic structure ; Density functional calculations ; Transition metals ; Cluster compounds ; Interstitial element ; Main-group elements ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The bonding in main-group atom-centered hexacapped transition-metal cubic clusters M8(μ8-E′)(μ4-E)6L8 has been analyzed by means of density functional theory (DFT) calculations. Although only one example of such compounds has been characterized so far, DFT results indicate that it should be possible for other members of this family to be synthesized. As for their metal-centered parents, there are several “magic” electron numbers that are able to satisfy the closed-shell requirement for such species, depending on the nature of the metal and the capping ligands. The most probable cluster valence electron counts that imply significant M-M bonding are 120 and 122. The former value is favored when E′ is an early main-group element while the latter value is favored when E′ is a late main-group element. Owing to the high connectivity between the atoms, such a regular cubic architecture may also be observed with open-shell electron configurations, as observed for the 119-cluster-valence-electron cluster Ni8(μ8-As)(μ4-As)6(PPh3)8.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
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