Marcin Gronowski

Computational Chemistry

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Posts Tagged ‘anions’

The C3N− anion: First detection of its electronic luminescence in rare gas solids

The 193 nm laser irradiation of cyanoacetylene HCCCN that was isolated in rare gas solids led to a long-lived luminescence origin at 3.58 eV, which was assigned to the a 3Σ+-X 1Σ+ system of cyanoacetylide CCCN−. The identification, which involved 15N and 2H isotopic substitution studies, is based on vibronic spacings in the phosphorescence spectrum compared to previous infrared absorption measurements and to theoretical results regarding CCCN− vibrational frequencies, as well as on a BD(T)/cc-pVTZ prediction for the singlet-triplet energy gap in this anion 3.61 eV. The same emission was also generated from Kr/HC3N mixtures subjected to a glow electric discharge immediately before the solidification cold-window-radial-discharge technique.
Full text: J. Chem. Phys. 128 (2008) 164304

C5N− anion and new carbenic isomers of cyanodiacetylene: A matrix isolation IR study

Products of the vacuum-UV photolysis of cyanodiacetylene HC5N in solid argon —the anion C5N−, imine HNC5, and the branched carbene C4(H)CN —have been identified by IR absorption spectroscopy, in addition to the already discovered isonitrile HC4NC. Spectral assignments were assisted by deuterium substitution experiments, by BD(T) calculations, and by the results of a recent density functional theory study.
Full text: J. Chem. Phys. 128 (2008) 154303

Matrix isolation IR spectroscopic and ab initio studies of C3N− and related species

Coupled cluster calculations were carried out for C3N−, CCNC−, C3N, CCNC, C3N+, and C3O. They support the experimental identification of the C3N− ion by means of matrix isolation infrared IR spectroscopy. The anion was generated in electric discharges through the cyanoacetylene isotopomers HC314N, HC315N, and 2HC3N, trapped in cryogenic rare gas matrices Ne, Ar, Kr, anddetected via its two most intense IR absorption bands, assigned to the 1 and 2 stretching vibrations. C3N− appears to be quite a stable anion, with a vertical detachment energy predicted to be as high as 4.42 eV. A large equilibrium electric dipole moment of 3.10 D facilitates the investigation of C3N− by microwave spectroscopy and radio astronomy. Various structural parameters and spectroscopic properties have been calculated for all tetra-atomic species considered.
Full text: J. Chem. Phys 128 (2008) 154305