DICYCLOPENTADIENYLDI-TERT-BUTOXYDICHROMIUM - PREPARATION, PROPERTIES, STRUCTURE, AND REACTIONS WITH SMALL UNSATURATED MOLECULES

Hydrocarbon solutions of chromocene react rapidly with alcohols, ROH, to give polymeric chromium (II) alkoxides (Cr(OR)2)x, where R=Me, Et, and;-Pr. The more sterically demanding and less acidic t-BuOH and R3SiOH (R=Me and Ph) react more slowly and lead to products of empirical formula CpCrO-t-Bu and CpCrOSiR3, respectively. The tert-butoxide complex, characterized by a number of physical techniques including single-crystal X-ray crystallography, is dinuclear, Cp2Cr2(O-r-Bu)2, with a nonplanar central (Cr-µ-O)2 moiety and a Cr-Cr distance of 2.65 (2) A. It is reactive toward a number of small unsaturated molecules including acetylenes, carbon monoxide, carbon dioxide, nitric oxide, and nitrous oxide. The reaction between CO2 and Cp2Cr2(O-r-Bu)2 in THF leads to chromocene and Cr2(O2CO-t-Bu)4(THF)2 which has been structurally characterized by single-crystal X-ray crystallography. Cr2(O2CO-t-Bu)4(THF)2 has the dichromium tetraacetate structure with a Cr-Cr distance of 2.367 (3) υ and axialiy coordinated THF molecules. The principal crvstallographic data for Cp2Cr2(O-t-Bu)2 are space group P21/n, a=15.102 (4) υ, b=18.712 (4) υ, c=14.413 (3) υ,'β=104.40 (2)°, V=3945 (2) υ3, and Z=8. The principal crystallographic data for Cr2(O2CO-t-Bu)4(THF)2 are space group P2Jc, a=10.011 (1) υ,b=9.852 (2) υ, c=19.477 (3) υ, β=104.74 (1)°, V=1857 (1) υ3, and Z=2. © 1979, American Chemical Society. All rights reserved.