Solvation of cyclopentadienyl and substituted cyclopentadienyl radicals in small clusters. II. Cyanocyclopentadienyl with polar solvents

Abstract

Clusters of the cyanocyclopentadienyl (CNcpd) radical and several polar solvent molecules (e.g., CF2H2, CF3H, CF3Cl, CH3Cl, ROH, H2O) created in a supersonic jet expansion are studied by laser induced fluorescence and hole burning spectroscopies. Lennard-Jones–Coulomb atom–atom potential energy calculations are employed in combination with ab initio calculations to aid in the interpretation of the observed spectra and to understand the nature of the radical polar solvent solvation behavior. The calculations predict quite reasonable cluster binding energies and structures, but are less accurate in predicting van der Waals vibrational mode energies and cluster spectroscopic shifts. The limitations of the atom–atom potential energy surface model in dealing with the more subtle aspects of CNcpd–polar solvent intermolecular interactions are discussed. Some possible causes of inadequacies of the approach are presented.

Vibronic coupling in cyclopentadienyl radical: A method for calculation of vibronic coupling constant and vibronic coupling density analysis

“…[12][13][14][15][16] After the ESR observations in condensed phase, the spectroscopy of the isolated radical has been reported. [17][18][19][20][21][22][23][24][25] After pioneering work by Liehr, 26 theoretical calculations have been piled up. [27][28][29][30] quite excellent, cyclopentadienyl radical is a good target for our calculation of the vibronic coupling.…”

The Jahn–Teller and related effects in the cyclopentadienyl radical. I. The ab initio calculation of spectroscopically observable parameters

“…Most of this work centered on the vibrational structure revealed by theà 2 A 2 ←X 2 E 1 electronic transition. [6][7][8][9][10] This work was supplemented by rotationally resolved work [11][12][13] on this transition's origin band and photo-detachment experiments 14 on C 5 H −…”

Differential Hydration of Phenol and Phenoxy Radical and the Energetics of the Phenol O−H Bond in Solution

“…These studies are useful because solvation is important for the understanding of the observed substituent effects on the spectra, structure, and chemistry of the phenoxy radical in water . Moreover, the differential solvation of phenol and phenoxy radical can be related to the energetics of the phenol O−H homolytic bond dissociation and to chemical reactivity in solution. ,− Modeling of solvent effects by “microsolvation” in clusters has also been employed to discuss the structure and energetics of several radical species including the methoxy radical, cyclopentadienyl radicals, − and the 2,5-lutidyl radical …”

“…19 Moreover, the differential solvation of phenol and phenoxy radical can be related to the energetics of the phenol O-H homolytic bond dissociation and to chemical reactivity in solution. 6,[20][21][22] Modeling of solvent effects by "microsolvation" in clusters has also been employed to discuss the structure and energetics of several radical species including the methoxy radical, 23 cyclopentadienyl radicals, [24][25][26] and the 2,5-lutidyl radical. 27 Statistical mechanics computer simulations can provide data on the structural and thermodynamic properties of liquids and solutions (see Dufy and Jorgensen for a recent review).…”