A theoretical investigation of the energetics and

Authors: Samiyara Begum Ranga Subramanian

Publish Date: 2015/12/09

Volume: 22, Issue: 1, Pages: 6-

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Abstract

The structural features spectroscopic properties and interaction energies of the linear protonbound complexes of OCH+ and its sulfur analog SCH+ with N2 were investigated using the highlevel ab initio methods MP2 and CCSDT as well as density functional theory with the augccpVXZ X = D T basis sets The rotational constants along with the vibrational frequencies of the cation–molecule complexes are reported here A comparison of the interaction energies of the OCH+–N2 and SCH+–N2 complexes with those of the OCH+–CO and OCH+–OC complexes was also performed The energies of all the complexes were determined at the complete basis set CBS limit CS shows higher proton affinity at the C site than CO does so the complex OCH+–N2 is relatively strongly bound and has a higher interaction energy than the SCH+–N2 complex Symmetryadapted perturbation theory SAPT was used to decompose the total interaction energies of the complexes into the attractive electrostatic interaction energy E elst induction energy E ind dispersion energy E disp and repulsive exchange energy E exch We found that the ratio of E ind to E disp is large for these linear protonbound complexes meaning that inductive effects are favored in these complexes The bonding characteristics of the linear complexes were elucidated using natural bond orbital NBO theory NBO analysis showed that the attractive interaction is caused by NBO charge transfer from the lone pair on N to the σC–H antibonding orbital in XCH+–N2 X = O S The quantum theory of atoms in molecules QTAIM was used to analyze the strengths of the various bonds within and between the cation and molecule in each of these protonbound complexes in terms of the electron density at bond critical points BCP

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