Simulation of Structure, Molecular Orbitals, Electron Density and Reactivity Aspects of Rubber Vulcanization Accelerator 2-Mercaptobenzothiazole by Density Functional Theory

V.K. Vijayan1, E. Purushothaman1, V. Arjunan2,3,* and S. Mohan4

1Department of Chemistry, University of Calicut, Calicut-673 635, India

2Department of Chemistry, Kanchi Mamuniavr Centre for Post-Graduate Studies, Puducherry-605 008, India

3Rajiv Gandhi Arts & Science College, Thavalakuppam, Puducherry-605 007, India

4School of Sciences and Humanities, Vel Tech University, Avadi, Chennai-600 062, India

*Corresponding author: E-mail: varjunftir@yahoo.com; varjun.ftir@gmail.com

Abstract

In this study, insights on the charge transfer and reactivity properties of 2-mercaptobenzothiazole are presented. The structural parameters are determined by B3LYP method. Delocalization of the lone pair electrons of S3 towards N1=C2 is possible and thereby decreases in force constant and increase in C2–S3 bond length than C2–S14. The C8–C9 bond distance increases due to the electron withdrawing nature of nitrogen. Negative electrostatic potentials reside on nitrogen whereas positive electrostatic potentials lie on hydrogen in S–H group. The LUMO–HOMO energy gap determines the charge transfer capacity and is equal to 5.1370 eV. The nS ® p*NC interaction between the sulphur (S3) lone pair and the N1=C2 antibonding orbital gives strong stabilization by 26.70 kcal mol–1. The nS ® p*NC interaction between the sulphur (S14) lone pair and the N1=C2 antibonding orbital gives stabilization by 23.77 kcal mol–1. The atoms C2, C8 and C9 are most prone to nucleophilic attack while the electrophilic attack on C2, C4 and C8 atoms. The C2, C4, C8 and C9 are more susceptible to free radical attack. The high first–order polarizability tensor reveals inductive interactions and second order polarizability tensors characterize the electron acceptor properties.

Keywords

2-Mercaptobenzothiazole, DFT, Natural bond orbital, Hyperpolarizability, Reactivity descriptors.

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