What is different between borazine-acetylene and benzene-acetylene? A matrix isolation and ab-initio study

Verma, Kanupriya

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https://hdl.handle.net/2142/91218 Copy

Description

Title

What is different between borazine-acetylene and benzene-acetylene? A matrix isolation and ab-initio study

Author(s)

Verma, Kanupriya

Contributor(s)

Viswanathan, K. S.

Issue Date

2016-06-20

Keyword(s)

Matrix isolation (and droplets)

Abstract

\flushleft{ Borazine (\chem{B_3N_3H_6})-\chem{C_2H_2} system was studied experimentally, using matrix isolation infrared spectroscopy and supported by \textit{ab-initio} computations. \chem{B_3N_3H_6}, also referred to as inorganic benzene, presents an interesting comparison with \chem{C_6H_6}. While \chem{C_6H_6} has a delocalized $\pi$ system, \chem{B_3N_3H_6} has electron density centered on the nitrogen atoms, while the boron atoms are electron deficient. In addition, \chem{B_3N_3H_6} can also serve as a proton donor through N-H group. Similarly, \chem{C_2H_2} can act both as a proton donor, using the hydrogen attached to the sp carbon or as a proton acceptor at its $\pi$-cloud. \\ At the MP2/aug-cc-pVDZ level of theory, \chem{C_6H_6}-\chem{C_2H_2} system showed three minima$\textsuperscript{1}$. The global minimum was a structure where the \chem{C_2H_2} was the proton donor to the \chem{C_6H_6} $\pi$ system. The next was a local minimum where the \chem{C_6H_6} was the proton donor to \chem{C_2H_2} and the third was a $\pi$ stacked structure. \\ \chem{B_3N_3H_6}-\chem{C_2H_2} also shows three minima at the same level of theory mentioned above. One was a structure where \chem{C_2H_2} donates a proton to \chem{B_3N_3H_6}, approaching it from above the plane of the ring, much like in \chem{C_6H_6}-\chem{C_2H_2}. A second near degenerate structure was also located where the \chem{C_2H_2} serves as a proton acceptor towards the N-H group of \chem{B_3N_3H_6}. A similar structure in \chem{C_6H_6}-\chem{C_2H_2} was a local minimum. While in the case of \chem{C_6H_6}-\chem{C_2H_2}, the global minimum was the only one observed in the experiments$\textsuperscript{2}$, in the case of \chem{B_3N_3H_6}-\chem{C_2H_2}, both near degenerate minima mentioned above were observed in the matrix. \chem{B_3N_3H_6}-\chem{C_2H_2} therefore reveals similarities and differences from the \chem{C_6H_6}-\chem{C_2H_2} system. A $\pi$-stacked local minimum was also computationally indicated in the \chem{B_3N_3H_6}-\chem{C_2H_2} system, though it was not observed in our experiments. Our earlier work comparing \chem{B_3N_3H_6}-\chem{H_2O} to \chem{C_6H_6}-\chem{H_2O} also yielded a similar behavioral pattern. Details of the experimental data and computational results will be presented.} \\ References: 1. M. Majumder, B. K. Mishra, N. Sathyamurthy Chem. Phys. Lett. 2013,557,59-65 \\ 2. K. Sundararajan, K.S. Viswanathan, A.D. Kulkarni and S.R. Gadre. J. Mol. Str. 2002,613,209-222.

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

text

Language

En

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http://hdl.handle.net/2142/91218

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Copyright 2016 by the authors

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