title: Reactivity, vibrational spectroscopy, internal rotation and thermochemical aspects of methylarsine.
abstract: The aim of this investigation was to perform a characterization of the spectroscopic and thermodynamic properties of methylarsine (CH3AsH2). Post-Hartree-Fock, 29 DFT methods and eight different composite methodologies were employed in these analyses. A comparison between harmonic and anharmonic frequency accuracies in reproducing the observable frequencies was performed here. In addition, the CH3AsH2→CH2AsH3isomerization barrier energy was estimated in 100kcalmol-1, whereas the H2-release routes barrier heights were in the 45-107kcalmol-1range. A rate constant of 10-66s-1was predicted regarding the isomerization route, while the CH2AsH3hydrogen elimination mechanism is faster than the methylarsine one. The transition state structure of the CH3AsH2internal rotational barrier energy varied between 1.0 and 1.4kcalmol-1. For the CH2AsH3internal rotation the estimated barrier heights varied 0.6-2.5kcalmol-1. The adiabatic ionization energy and the heat of formation each structure was also calculated here.
authors: Departamento de Química e Física Molecular, Instituto de Química de São Carlos, Universidade de São Paulo, USP, São Carlos, SP, Brazil. Electronic address: rommelbv@yahoo.com.br.
authors: Rommel B
authors: RB
authors: Viana
keywords: Charge analysis; Kinetics; Partition coefficient; Unimolecular rearrangement