A DFT study of the structure and bonding in 1, 3-dithia -2-arsacyclopetane derivatives with oxygen and sulfur donor ligands such as Acetic acid and Thioacetic acid

S. Trivedi; B. R. Patil; R. Prasad; S. Patil

Abstract

A DFT study of the structure and bonding in 1, 3-dithia -2-arsacyclopetane derivatives with oxygen and sulfur donor ligands such as Acetic acid and Thioacetic acid

Author(s): S. Trivedi, B. R. Patil, R. Prasad and S. Patil

A quantum mechanical analysis of 1,3-dithia-2-arsacyclopentane derivatives with oxygen and sulfur donor ligands such as acetic acid (compound 1) and thioacetic acid (compound 2), have been performed with the objective of exploring their electronic, structural and spectral behavior on the basis of density functional theory. The geometrical parameters, band gap and assignment of important vibration frequencies are reported. In compound 2 the As-S (ligand) bond length 2.40 A0 is slightly higher than As-S (1, 3-dithia-2-arsacyclopentane moity) bond length 2.35 A0. In compound 2 the C-C bonds are more stable than C-S bonds and in compound 1 the C-O bonds are more stable than C-C bonds. The bond length suggests that compound 2 should be more reactive than compound 1. Bonds around heavy metal As are found longer than all other bonds suggesting that active sites in both undertaken compounds are centered around As. Bond angle analysis around heavy metal As suggest SP3 hybridization on As atom. Therefore the structure of undertaken compounds can be assumed to be distorted tetrahedral. Analysis of dihedral angles reveals that cyclopetane moiety is not planer and ligand is not co planer to cyclopentane moiety. As1 is most positive element it suggest maximum reactivity around As1. The total energies of the two compounds are found to -3339.38 a.u and -3662.34 a.u. suggesting sulfur complex to be much more stable compared to oxygen complex. On the other hand compound1 is more polar than compound2. The energy gap in the two complexes is found to be 5.07 eV (245 nm) and 4.75 eV (261 nm) respectively. An important feature is that the compound 1 undergoes rotation about O2-C3 and O1-As bonds to produce one more conformer in which ligand is cis to the 1, 3-dithia -2-arsacyclopetane group. The compound 1 is stabilized by hydrogen bonding. For compound 1 zero-point vibrational energy is found to be 291633.6 (Joules/Mol) or 69.70210 (Kcal/Mol) with zero-point correction 0.111077 (Hartree/Particle) and for compound 2 zero-point vibrational energy is found 283863.8 (Joules/Mol) or 67.84509 (Kcal/Mol) with zero-point correction 0.108118 (Hartree/Particle)

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