ARGON MATRIX ISOLATION STUDIES OF $HCo(CO)_{4}$ AND ITS REACTIVE INTERMEDIATES
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Date
1978
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Ohio State University
Abstract
The first spectroscopic evidence for $HCo(CO)_{3}$, a postulated but previously unobserved intermediate in the catalytic oxo reaction, has been found in the infrared studies of matrix isolated $HCo(CO)_{4}$ Spectra of samples of $Ar/HCo(CO)_{4}$ showed bands corresponding to literature data for $HCo(CO)_{4}$ and $\cdot CO(CO)_{4}$, as well as a very weak band at $2018\, cm^{-1}$. Ultra-violet irradiation of the matrix led to considerable growth of the $2018\, cm^{-1}$ bands, as well as to the appearance of bands at 485 and $2025\, cm^{-1}$. Evidence suggests that the 485, 2018 and $2025\, cm^{-1}$ bands can be attributed to the same species. Photolytic decarbonylation of transition metal car-bonyls is well documented, and consequently these three bands are assigned to the matrix isolated $HCo(CO)_{3}$ species. In an $N_{2}$ matrix, the upper bands appear as a poorly resolved doublet at 2013 and $2017\, cm^{-1}$. The doublet is assigned to two site split components of a degenerate carbonyl band. In addition, upon photolysis of a mixture of $Ar/HCo(CO)_{4}$ and $Ar/C_{2}H_{4}$, new bands are formed which have been tentatively assigned to the $HCo(CO)_{3}/C_{2}H_{4}$ complex, $\cdot CO(CO)_{4}$ was also detected in a number of these experiments, and its presence appeared to be due to the decomposition of the $HCo(CO)_{4}$ in the stainless steel deposition tube. Photolysis of $Co(CO)_{4}$ yielded bands which are in agreement with literature values for $Co(CO)_{x}$ with $x = 1,2$ and 3.
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Author Institution: Department of Chemistry, University of Cincinnati