1. Kanupriya Verma, K.S.Viswanathan Department of Chemical Sciences
What is different between Borazine-Acetylene and Benzene-Acetylene? A Matrix Isolation Infrared and ab initio study
Kanupriya Verma, K.S.Viswanathan
Department of Chemical Sciences
Indian Institute of Science Education & Research, Mohali, Punjab

2. Outline Introduction Matrix Isolation-The technique
Experimental Details
Computational Details
Conclusion

3. Borazine-“Inorganic Benzene”
Isoelectronic and isostructural analog of C6H6.
Hence comparing the complexes of C6H6 and B3N3H6 is interesting.
Extremely sensitive to moisture, thus posing a challenge to study this system.
1.01 Å
1.20 Å
1.43 Å
Structure of B3N3H6 at MP2/aug-cc-pVDZ level.

4. Matrix Isolation Technique
Sample +
Matrix gas
Vacuum chamber
Substrate at low Temperature
Molecules of interest are diluted with a large excess of an inert gas and the mixture then condensed onto a cold substrate. MI spectra studied using IR spectroscopy.
Advantages
Low temperature- only the lowest vibrational and electronic levels and
possibly lowest rotational levels populated.
Sharp line widths
What can be studied?
transient/short lived species
weak non-covalent interactions
molecular conformations

6. Computational Details
Geometry Optimisation-MP2/ G**&MP2/aug-cc-pVDZ
Frequency Calculation-MP2/aug-cc-pVDZ
AIM analysis-MP2/aug-cc-pVDZ
EDA analysis-MP2/aug-cc-pVDZ

7. Optimised geometries of B3N3H6-C2H2 complexes at MP2/aug-cc-pVDZ
π-stacked
3.41 Å
-0.97
T shaped-Ac
BSSE Corr.Energy(kcal/mol)
2.42 Å
T shaped-NH
Bent NH…C
-1.65
2.43 Å
2.63 Å
-1.85
-2.03

8. Ar matrix

9. π-stacked
T-ac
T-NH
Bent NH..C

10. Energy Decomposition Analysis of B3N3H6-C2H2 complexes
Energy (kcal/mol)

11. Conclusions In C6H6-C2H2, ≡C-H…π complex is the global minimum;
while in B3N3H6-C2H2, a bent N-H…C complex is the global minimum.
C2H2 served as the proton donor in the C6H6-C2H2 global minimum, while in B3N3H6-C2H2 global minimum, C2H2 served as the proton acceptor, thus clearly showing a switch in roles.
EDA analysis showed almost equal contributions of dispersion and electrostatic energies for the global minimum in both systems.
H…π for C6H6-C2H2 &
Bent NH…C for B3N3H6-C2H2

12. Acknowledgement
I thank my research supervisor Prof. K.S.Viswanathan and lab members Jyoti, Pankaj, Ginny and Dr. Anamika.
I thank Dr. Sanjay Singh and Deependra Bawari for the help in synthesis of borazine.
I thank MHRD and IISER Mohali, India for the research infrastructure and facilities.

13. Thank You