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'Thermodynamics' in keywords Facet   Publication Year 1991  [X]
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1Author    Patrizia Lau, G. Ottfried Hüttner, Laszlo ZsolnaiRequires cookie*
 Title    Reversible Öffnung von Metall-Metall-Bindungen: Quantitative Untersuchung des RingÖffnungsgleichgewichts von [Cp'(CO)2Mn]2SeAryl+ Reversible Opening of Metal Metal Bonds: Quantitative Analysis o f the Ring Opening Equilibrium for [Cp'(CO)2Mn]2SeAryl+  
 Abstract    The com pounds [Cp'(CO)2Mn]2S eR + are isoelectronic analogues o f the well known "inide-ne"-species [L"M]ER (E = P, As, Sb, Bi). While these latter "inidene" com pounds exist in an open form with no metal-metal-interaction and the main group atom in a trigonal planar envi­ ronment allowing for a three-center-4 ^-system M—E—M, their isoelectronic selenium ana­ logues generally show equilibria between the "inidene"-type metal metal non bonded forms and their metal metal bond closed cyclic isomers. In a valence bond picture the four electrons, delocalized in the three-center-4 ^-system o f the open isomers, are localized in the closed ones: two in the metal metal bond and two as a lone pair at a pyramidally coordinated selenium center. The corresponding equilibria are quantitatively analyzed for [Cp'(CO)-,Mn]-,SeR + (R = ' C F j -Q H , (1), /'C H ,-C 6H4 ('Tol) (2), °CH3-C !,H4 (°Tol) (3)) by U V /V IS spectroscopy o f their solutions at different temperatures. The ring opening process which corresponds to the reversible opening o f a metal metal bond is found to be entropically driven with reac-tion-entropies o f around 25 [JK-lm ol-1]. Correspondingly, imposing steric hindrance on R, [Cp'(CO)2Mn]2SeM es+ (4) yields a stable bond opened "inidene"-type com pound. Reducing steric hindrance in [Cp'(CO)2Mn]2Se'Pr+ (5) gives the bond closed form as the only detectable isomer. 
  Reference    Z. Naturforsch. 46b, 719—7 (1991); eingegangen am 16. Oktober 1990 
  Published    1991 
  Keywords    Reversible Metal Metal Bond Opening, Thermodynamics, "Inidene" Com pounds, Selenylium Ligands 
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 TEI-XML for    default:Reihe_B/46/ZNB-1991-46b-0719.pdf 
 Identifier    ZNB-1991-46b-0719 
 Volume    46