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'Carbene Complexes' in keywords Facet   Publication Year 1983  [X]
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1983[X]
1Author    Wolfgang Malisch, Herbert Blau, Peter Weickert, Karl-Heinz GrießmannRequires cookie*
 Title    Zur Reaktion von Metall-koordiniertem Kohlenmonoxid mit Yliden, X [1] /3-Phosphoniocarben-, ß-Phosphonio vinyl-und Phosphor-Ylid-Komplexe des Chroms und Cobalts aus Tetramethylphosphonium- [(trimethylphosphoranyliden)acetyl-metallaten] Reactions of Metal Coordinated Carbon Monoxide with Ylides, X [1] ^-Phosphoniocarbene, /9-Phosphoniovinyl and Phosphorus Ylide Complexes of Chromium and Cobalt Deriving from Tetramethylphosphonium [(trimethylphosphoranyliden)- acetyl-metallates]  
 Abstract    The reaction of Cp(CO)2(NO)Cr with Me3P = CH2 yields the tetramethylphosphonium -[(trimethylphosphoranyliden)acetyl-Chromate] Me4P[Cp (CO)(NO)Cr-C(O)-CH = PMe3] (1) via ylide addition at the carbonyl carbon and transylidation. A reversible equilibrium is established between 1 and the starting materials, which is responsible for the facile conversion of 1 into the ylide complex Cp(CO)(NO)Cr-CH2PMe3 (2) on photolysis. In the presence of Mel, 1 is degradated to [Me4P]I, [Me3PEt]I, [Me2PEt2]I and Cp(CO)2(NO)Cr. Treatment of 1 with an equimolar amount of Me0S02F leads to the formation of the "zwitterionic" phosphoniovinyl complexes Cp(CO)(NO)Cr-C(OMe) = CH-PMe3 (3a) and Cp(CO)(NO)Cr-C(OMe) = C(Me)-PMe3 (3b). With excess Me0S02F the phosphoniocarbene complex [Cp(C0)(N0)Cr = C(0Me)-CH(Me)-PMe3]S03F (4a) is obtained. Me3P = CH2 de-protonates 4a to 3b, which adds HCl to give [Cp(CO)(NO)Cr=C(OMe)-CH(Me)-PMe3]Cl (4b). The phosphonium cobaltacylates Me4P[(C0)(N0)(L)C0-C(0)-CH = PMe3] (5a, b), generated from the cobalt complex (CO)2(NO)(L)Co (L = CO, Me3P) and Me3P = CH2, readily transform to the ylide complexes (CO)(NO)(L)Co-CH2-PMe3 (6a, b). MeX (X = I, S03F) cleaves 6b to give (CO)2(NO)(Me3P)Co and [Me3PEt]X. The new complexes are characterized by elementary analysis and spectroscopy. 
  Reference    Z. Naturforsch. 38b, 711—718 (1983); eingegangen am 18. Januar 1983 
  Published    1983 
  Keywords    Carbonmonoxide Conversion, Vinyl Complexes, Carbene Complexes, Ambidentate Nucleophilic Reactivity 
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 TEI-XML for    default:Reihe_B/38/ZNB-1983-38b-0711.pdf 
 Identifier    ZNB-1983-38b-0711 
 Volume    38 
2Author    C. Krüger, R. Goddard, K. H. ClausRequires cookie*
 Title    The Experimental Determination of the Electronic Deformation Densities in a Chromium Carbene and a Chromium Carbyne Complex  
 Abstract    The electronic deformation densities for pentacarbonylmethylethoxycarbenechromium I and chlorotetracarbonylethylidynechromium II have been experimentally determined using Neutron (for I) and X-ray diffracted intensities measured from single crystals at 100 K. A build up of electron density in all bonds and around each chromium atom is observed. Deformation density maxima are directed along the 3-fold axes of the approx-imately octahedrally coordinated metal atoms and presumably represent occupation of the t2g d-orbital set. The observed electron density distributions indicate that intermole-cular bonding has an important influence on the distribution of electron density in the molecules. Seit ihrer Entdeckung und strukturchemischen Beschreibung [1] stehen Übergangsmetallkomplexe mit Carben-und Carbin-Fragmenten im Blickfeld theoretischer Betrachtungen [2]. Ziel der vorliegen-den Arbeit war es, einen experimentellen Zugang zu den Bindungs Verhältnissen mit Hilfe neuer, hochauflösender Röntgen-(X-X)-[3] und Neu-tronenbeugungsmethoden (X-N) [4, 5] zu finden. Wir beschreiben im folgenden unsere Untersuchun-gen an Einkristallen des Chrom-Carben-Komplexes I sowie des Chrom-Carbin-Komplexes II. Alle experimentellen Angaben zur Datensamm-lung sowie zur Struktur bear beitung sind in Tab. I zusammengefaßt. Die umfangreichen Röntgenda-tensätze wurden auf einem speziell präparierten, rechnergesteuerten Diffraktometer (Enraf-Nonius-CAD 4) unter Verwendung eines von uns eigens entwickelten, über längere Zeiträume eine stabile (± 0,2 K) Temperatur gewährleistenden Tieftem-peratur-Zusatzes gesammelt. Die Sammlung der entsprechenden Neutronen-beugungsdaten für I erfolgte am ILL Grenoble mit 
  Reference    Z. Naturforsch. 38b, 1431—1440 (1983); eingegangen am 11. Juli 1983 
  Published    1983 
  Keywords    Carbene Complexes, Carbyne Complexes, Structural Analysis, Electronic Deformation Densities 
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 TEI-XML for    default:Reihe_B/38/ZNB-1983-38b-1431.pdf 
 Identifier    ZNB-1983-38b-1431 
 Volume    38