Orientation dependence of the Na + CH₃NO₂ charge-transfer reaction

Abstract

The reaction of atomic sodium with nitromethane, CH₃NO₂, was studied using the B3LYP//6-311++G(3df,3pd) level of theory to investigate the orientation dependence of the charge-transfer type reaction. Excellent agreement was found between ground state interaction potentials and recent molecular beam orientation experimental data for free and . CH₃NO₂ shows slight steric asymmetry for the approach geometry of Na, with reaction favouring attack from the NO₂-end at relatively low (few eV) energies. Increasing reaction energy allows CH₃-end orientations to become accessible and new fragmentation processes to occur. Results indicate that an interpretation involving charge-transfer at relatively large separation, where the positive metal core plays little role in the dynamics following charge-transfer would not be correct. Coulombic interactions through ion-pair formation facilitate these reactions and, in part, explain some of the previously reported experimental steric asymmetry on this system. Dipole-bound states appear not to play a major role in reaction dynamics.

¹Dedicated to Fritz Schaefer on his 65th birthday.

Keywords:

• orientation dependence
• nitromethane
• CH₃NO₂
• charge-transfer
• ion-pairs

Acknowledgements

JNB acknowledges the financial support of a Tertiary Education Commission Top Achiever Scholarship.

Notes

¹Dedicated to Fritz Schaefer on his 65th birthday.