Bisbenzene chromium

Bisbenzene chromium and bistoluene chromium display, in the lower I.E. region of their P.E. spectra, two bands in the region below 8 eV, easily attributed to ionizations from the fully occupied and d-orbitals. Above 8 eV there is strict sim-... 

Bisarene chromium compounds have been shown to undergo reversible exchange with aromatic hydrocarbons in the presence of aluminum trihalides (207). The exchange reaction has been used to improve the preparation of the bisbenzene chromium cation via the more readily prepared bismesitylene chromium cation 157b). 

Cocondensation of metal vapor and organic ligands at liquid nitrogen temperature has proved to be a very useful method for preparing organometallic compounds of the first-row transition elements 409), as exemplified by the synthesis of bisbenzene chromium 408) ... 

Bisbenzene chromium reacts with good 77-acceptor Lewis acids to form complexes (CgHg)2Cr L" (L = tetracyanoethylene, trinitrobenzene, -quinone, chloranil) in which electron transfer from the (CgHg)2Cr to the Lewis acid has taken place. The complexes are best described as bisbenzene chromium cation salts of radical anions (765). The crystal structure of one such compound [(MeCgHg)2Cr] (TCNQ) (TCNQ = 7,7,8,8-tetracyanoquinodimethane) has been determined and consists of Stacks of TCNQ anions and bisbenzene chromium cations with interplanar spacings of 3.42 A (577). 

Bisbenzene chromium has been found to be a catalyst for the polymerization of ethylene at 200°-250°C. Chromium metal was postulated as the active catalyst in the system 410, 411). The polymerization of ethylene by bisarene chromium(I) salts in the presence of (i-Bu)3Al has also been studied (406). The catalytic activity was found to be a function of both the arene and the anion present. When bisarene chromium complexes are air oxidized in water, hydrogen peroxide is produced ... 

The other compound of this type for which thermochemical data are available is chromium bisbenzene, Cr(CgHg)2. The mean dissociation energy for the bond between the metal and the benzene ring may be calculated using the value g) — +19 82... 

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