Chemical synthesis using metal atoms. Matrix infrared, Raman, ultraviolet-visible, and electron spin resonance studies of the binary carbonyls of cobalt, Co(CO)n (where n = 1-4), and the distortion problem in tetracarbonylcobalt
| Autor: | Geoffrey A. Ozin, Helmut Huber, E. P. Kuendig, B. R. McGarvey, L. Hanlan |
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| Rok vydání: | 1975 |
| Předmět: |
Ligand field theory
Infrared Analytical chemistry General Chemistry Biochemistry Catalysis law.invention chemistry.chemical_compound symbols.namesake Colloid and Surface Chemistry chemistry law symbols Molecule Raman spectroscopy Spectroscopy Electron paramagnetic resonance Hyperfine structure Carbon monoxide |
| Zdroj: | Journal of the American Chemical Society. 97:7054-7068 |
| ISSN: | 1520-5126 0002-7863 |
| Popis: | The cocondensation reactions of Co atoms with CO at 6 to 15$sup 0$K were investigated for the first time using matrix infrared, Raman, uv-visible, and ESR spectroscopy. Using extremely low Co concentrations (Co:M approximately equal to 1:10$sup 4$ to 1:10$sup 5$) which were found to favor the formation of mononuclear complexes, variable concentration $sup 12$C$sup 16$O--M experiments (where M = Ne, Ar, Kr, or Xe), $sup 12$C$sup 16$O--$sup 13$C$sup 16$O and $sup 12$C$sup 16$O--$sup 12$C$sup 18$O--M mixed isotopic substitution, in conjunction with matrix warm-up experiments, the reaction products were found to be Co(CO)/ sub n/ (where n = 1 to 4). The vibrational spectroscopic data and isotope frequency calculations for Co($sup 12$C$sup 16$O)/sub n/($sup 13$C$sup 16$O)/sub 4-n/ (where n = 0 to 4) in carbon monoxide matrices favor a C/sub 3v/ trigonally distorted tetrahedral structure for Co(CO)$sub 4$. The corresponding ESR spectrum supports the contention that the molecule has axial symmetry and S = $sup 1$/$sub 2$. The spin-Hamiltonian parameters are g/sub parallel/ = 2.007 +- 0.010, g/sub perpendicular/ = 2.128 +- 0.010, A/sub parallel/($sup 59$Co) = (58 +- 1) x 10$sup -4$ cm$sup -1$, and A/sub perpendicular/($sup 59$Co) = (55 +- 1) x 10$sup -4$ cm$sup -1$ and aremore » found to be consistent with a C/sub 3v/ trigonal distortion. Striking confirmation of the C/sub 3v/ distortion is obtained from the $sup 13$C hyperfine splitting of Co($sup 13$C$sup 16$O)$sub 4$ in 93 percent $sup 13$C$sup 16$O. The corresponding uv-visible spectrum displays ligand field and charge transfer bands in the region 200-350 nm. The ESR data for Co(CO)$sub 4$ in Ar matrices provide evidence for two forms of the molecule, Co(CO)$sub 4$(I) and Co(CO)$sub 4$(II). Co(CO)$sub 4$(I) is favored on deposition at 6 to 8$sup 0$K while Co(CO)$sub 4$(II) predominates at 30 to 35$sup 0$K. (auth)« less |
| Databáze: | OpenAIRE |
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