Metall-π-Komplexe von Benzolderivaten, XL a <br />Selen in der Peripherie des Bis(benzol)chroms: Darstellung, Strukturdynamik und Redoxverhalten eines neuen Hetera-[3]-chromocyclophans / Metal-π Complexes of Benzene Derivatives, XL a <br />Selenium in the Periphery of Bis(benzene)chromium: Synthesis, Structural Dynamics, and Redox Behavior of a New Hetera-[3]-chromocyclophane
1992; De Gruyter; Volume: 47; Issue: 8 Linguagem: Inglês
10.1515/znb-1992-0817
ISSN1865-7117
AutoresChristoph Elschenbroich, Heike Burdorf, Helmut Burdorf, Dagmar Mahrwald, Bernhard Metz,
Tópico(s)Lanthanide and Transition Metal Complexes
ResumoLithiation of bis(benzene)chromium and subsequent reaction with Ph 2 Se 2 or Se and CH 3 I, respectively, afforded the complexes (PhSe-η 6 -C 6 H 5 ) 2 Cr (6) and (MeSe-η 6 -C 6 H 5 ) 2 Cr (8), the latter being convertible into interannularly bridged (MeSe-η 6 -C 6 H 5 ) 2 Cr[M(CO) 4 ] (9-11, M = Cr, Mo, W). According to 1 H NMR spectroscopy, 9 undergoes both bridge inversion and reversal, the former displaying spectral coalescence at 283 K (ΔG c ≠ = 55.9 kJ mol -1 ) whereas the latter is still rapid at 200 K. Substitution of H for –SeMe and addition of a Cr(CO) 4 unit effect anodic shifts of the redox potential E 1/2 (+/0) of 95 mV/SeMe and 230 mV/Cr(CO) 4 . Despite electron donation from the bis(arene)metal backbone 8 is a fairly weak ligand, cleavage of the interannular bridge occuring with the half life τ 1/2 = 41.4 min (9→8) and τ 1/2 = 5.8 s (9 +• →8 + ) as inferred from cyclic voltammetry in DME at 293 K.
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