A matrix isolation i.r. study on molecular complexes of hexamethylbenzene and tetracyanoethylene

Structural and vibrational characterization of tetracyanoethylene-hexamethylbenzene as a function of pressure

The neutron powder diffraction and inelastic neutron scattering (INS) spectra of the electron donor-acceptor complex, tetracyanoethylene-hexamethylbenzene have been studied as a function of pressure to 0.414 GPa. Using the PW91 and PBE density functional theories, the unit cell vectors were calculated as a function of pressure and are compared to those experimentally obtained from the diffraction data. The calculated lattice vectors display large errors at low pressures but were found to be in close agreement with the experimental vectors at 0.414 GPa. Comparison of the experimental INS spectra of the TCNE-HMB enabled assignment of specific vibrational modes while providing a direct measurement of the effect of pressure on the complex. The PW91 vibrational frequency calculations reproduced both the vibrational intensities and frequencies with relative accuracy.

Matrix isolation investigation of the photochemical reaction of methyl-substituted benzenes with CrCl2O2

The matrix isolation technique, combined with infrared spectroscopy, has been used to characterize the products of the photochemical reactions of toluene, m-, o-, and p-xylene, mesitylene, and hexamethylbenzene with CrCl2O2. 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. The irradiation was shown to lead to oxygen atom transfer, forming complexes between methylcyclohexadienone derivatives and CrCl2O. With the xylenes and mesitylene, di- and trimethylphenols, complexed to CrCl2O, were also observed, respectively. This latter result arises from C-H bond activation and oxygen atom insertion into a C-H bond. The identification of the complexes was further supported by isotopic labeling (2H) and by density functional calculations at the B3LYP/6-311G++(d,2p) level. Product distributions were rationalized by an analysis of the electron density distribution.