Photoelectron spectra of the negative ions Ni(CO)"-, = 1-3, obtained with a fixed-frequency argon-ion laser operating at 488 nm are reported. The spectra provide the electron affinities for this series, EA[Ni(CO)] = 0.804 ± 0.012 eV, EA[Ni(CO)2] = 0.643 ± 0.014 eV, and EA[Ni(CO)3] = 1.077 ± 0.013 eV. The symmetric C-0 vibrational frequencies for the neutral complexes are obtained from the spectra. Metal-carbonyl bond strengths for the neutral carbonyls, Ni(CO)", = 1-4, are derived from these and other data. Electronic and geometric structure of ions and neutrals is also discussed.
Muetterties et al. / Reaction Scope f o r the v3-C3H~Co[P(OCH3)3/j Catalyst 2405 termined as low-spin iron (S = ' /2) while monoimidazolehemin was reported as high-spin iron (S = Abstract: The scope and selectivity of q3-C3H5Co[P(OCH3)3]3 as a catallst precursor for the homogeneous hydrogenation of arenes at room temperature and low pressure (1-3 atrn) have been examined for a variety of substituted benzenes and polycyclic aromatic and heterocyclic compounds. Pronounced stereoselectivity for the cis addition of Hz and the formation of cis ring junctions has been observed. For example, benzene + Dz gave 295% all cis C6H6D6, naphthalene + Hz gave cis-decalin with no detectable trans isomer. and anthracene + Hz gave >95% of the cis-sjn-cis-perhydroanthracene. The scope of the reaction is reasonably large. Catalytic hydrogenation was demonstrated for benzenes with substitutent groups that include -R, -OR, -COOR, -COR, -CH=CHR, -C-CR, and -NRz. The catalyst system is subject to steric inhibition by ring substituents on the arene ring. Electron-withdrawing and nucleophilic substituents such as halogen, -NO>, and -CY also inhibit the reaction. The selectivity for arene vs. olefin hydrogenation in competitive systems is discussed. Comparisons are drawn with metal surface catalyzed hydrogenation
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