CYCLO-DIMERIZATION OF ACETYLENES TO CYCLOBUTADIENE PROBLEM - SYNTHESIS, CRYSTAL AND MOLECULAR-STRUCTURE OF (ETA-5-CYCLOPENTADIENYL)- (ETA-4-1,2-DIPHENYLCYCLOBUTA[L]PHENANTHRENE)RHODIUM
Academic Article
Overview
Research
Identity
Additional Document Info
Other
View All
Overview
abstract
A reaction between 2,2-bis(phenylethynyl)biphenyl and 5-cyclopentadienylcarbonylrhodium has been found to produce several organometallic products, including (5-cyclopentadienyl)(4-1,2-diphenylcyclobuta[l]phenanthrene)rhodium has been determined by single-crystal X-ray diffraction using data acquired by a computer-controlled diffractometer. The substance crystallizes in the triclinic system, space group P1, with cell constant of a 10.023(1), b 11.146(3), c 22.314(4) , 101.26(2), 97.53(1) and 96.55(1). The observed and calculated densities (for two molecules in the asymmetric unit) are 1.45(1) and 1.446 g/cm3, respectively. The structure was solved by Patterson, Fourier and least-squares refinement techniques. Final discrepancy indices are R(F) - 3.6% and Rw(E) = 4.2%. The (5-C5H5)Rh fragments have a normal disctances and angles, the Cp rings being planar as expected. The cyclobutadiene rings are also planar (largest deviations from planarity being 0.003 ) and parallel to the Cp rings. The most important change, as a result of the constraints of the fused cyclobuta[l]phenanthrene system, is the trapezoidal shape of the (4-C4) ring. The effects of fusion and of strain, caused by the crowding of two hydrogen atoms at the open side of phenanthrene, on the cyclobuta[l]-phenanthrene system are discussed. 1980.
