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Organometallic Electrochemistry. XVI.’ Electric Charge Distribution in Organometallic Compounds. Olefin-Iron Tetracarbonyls Raymond E. Dessy, John C. Charkoudian,2 Tom P. Abeles, and Arnold L. Rheingold Contribution from the Department of Chemistry, Virginia Polytechnic Institute, Blacksburg, Virginia 24061. Received October 22, 1969 Abstract: Mossbauer, ir, uv-visible, esr, and electrochemical studies on a series of trigonal bipyramidal iron
compounds have yielded definitive information concerning the transmission of electrical charge to and through the metal atom before and after one-electron reduction. For the neutral compound in solution, infrared results suggest the olefin antibonding orbitals lie in the trigonal plane, as evidenced by evaluation of -0 force constants using the C-K force field approximation method (kl > kz). Upon reduction to the radical anions, these species exhibit large shifts to longer wavelength for all CO stretching modes, with Akl > Ak2. Esr spectra demonstrate high localization of unpaired spin density in an orbital predominantly ligand in character. Such observations are consistent with a radical of the ligand (>C=C
