Matrix Isolation Investigation of the Photochemical Reaction of Benzene with CrCl₂O₂ and OVCl₃

Abstract

The matrix isolation technique, combined with infrared spectroscopy, has been used to characterize the products of the photochemical reactions of benzene with CrCl(2)O(2) and OVCl(3). While initial twin jet deposition of the reagents led to no visible changes in the recorded spectra, strong product bands were noted following irradiation with light of lambda > 300 nm. Wavelength dependence studies determined that light of lambda < 590 nm led to reaction and oxygen atom transfer, forming an eta(1)-complex between 2,4-cyclohexadienone and CrCl(2)O. The identification of the complex was further supported by isotopic labeling ((13)C and (2)H) and by density functional calculations at the B3LYP/6-311G++(d,2p) level. Merged-jet experiments in which thermal reactions are examined were also conducted, at temperatures as high as 150 degrees C. No products were observed.

Matrix isolation and theoretical investigation of the photochemical reaction of CrCl2O2 with benzenes substituted with electron withdrawing groups

“…However, subsequent irradiation of these matrices led to the formation of product bands in a manner that is similar to the previous systems studied in this lab [23,[32][33][34]. Since diffusion of most molecules does not occur within the argon lattice at 14 K, for a photochemical reaction to occur after twin jet deposition the reactants must be trapped within the same matrix cage.…”

“…Excitation into these charge transfer transitions has then been shown to lead to photochemical reaction for a number of systems. However, visible/UV spectra recorded in the earlier Ar/ CrCl 2 O 2 + Ar/benzene study [33] did not show any distinct new electronic absorptions. This was consistent with the lack of observation of a distinct molecular complex in the infrared upon initial matrix deposition.…”

“…Past studies in this laboratory have examined the matrixisolated products of the thermal and photochemical reactions of CrCl 2 O 2 , OVCl 3 , and OVF 3 with organic and inorganic substrates [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32]. Specifically, two recent studies in this lab [33,34] examined the reactions of CrCl 2 O 2 with benzene and with methyl-substituted benzenes. In the first system, light of k > 590 nm led to reaction and oxygen atom transfer, forming a complex between 2,4-cyclohexadienone and CrCl 2 O.…”

Infrared matrix isolation study of the oxidation of H2S by CrCl2O2

“…Recent matrix isolation studies from this laboratory have investigated the thermal and photochemical reactions of high valent transition metal compounds, including CrO 2 Cl 2 , with a number of small organic and inorganic substrates. [10][11][12][13] Two classes of reactions have been observed to date, the first of which was the formation of an initial molecular complex, followed by HCl elimination from the complex and addition of the organic (or inorganic) fragment to the metal center to retain a 4-coordinate com-plex. 10,11 The second is oxygen transfer from the metal center to the substrate, leading to an oxidized substrate species.…”

Chemistry in low-temperature matrices

“…Oxygen transfer also occurs when these oxo-metal reagents are photolysed in low temperature matrices containing benzene. 279 Here the products with CrO 2 Cl 2 is identified as an Z 1 complex between 2,4-cyclohexadienone and CrCl 2 O. Interestingly, in this case, no initial complex was seen on deposition, nor were any thermal reactions observed when merged-jet deposition up to 150 1C was employed. Acetone, Me 2 CO, reacts with OVCl 3 in a rather more complex manner.…”