Probing the Electronic Structures and Properties of Neutral and Charged Monomethylated Arsenic Species (CH3Asn(-1,0,+1), n=1-7) Using Gaussian-3 Theory

The structures and energies of neutral and charged monomethylated arsenic species CH3Asn(-1,0,+1) (n = 1-7) have been systematically investigated with the Gaussian-3 (G3) method. The ground-state structures of monomethylated arsenic species including the neutrals and the ions are vertex-methylated type. The lowest-energy structures of neutral methylated arsenic species and their ions can be viewed as being derived from corresponding to neutral and ionic arsenic clusters, respectively. The reliable electron affinities and ionization potentials of CH3Asn have been evaluated. And there are odd even alternations in both electron affinities and ionization potentials as a function of size of CH3Asn The dissociation energies of CH3 from neutral CH3Asn and their ions have been calculated to examine relative stabilities. The results characterized the odd-numbered neutral CH3Asn as more stable than the even-numbered systems, and the even-numbered cationic CH3Asn+ as more stable than the odd-numbered species with the exception of n = 1. The dissociation energy of CH3As+ is the maximum among all of these values. There are no odd even alternations for anionic CH3Asn- with n <= 7.