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A New Approach to Design High Spin Organic Systems: Aromatic Stabilization with Exo‐cyclic π Electrons Plays Crucial Role
Author(s) -
Das Soumik,
Homray Manoswita,
Misra Anirban
Publication year - 2020
Publication title -
chemistryselect
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.437
H-Index - 34
ISSN - 2365-6549
DOI - 10.1002/slct.202003493
Subject(s) - delocalized electron , aromaticity , ring (chemistry) , singlet state , chemistry , electron , homo/lumo , atom (system on chip) , electron delocalization , radical , density functional theory , crystallography , computational chemistry , atomic physics , molecule , physics , organic chemistry , excited state , quantum mechanics , computer science , embedded system
Radicals are important because of their diverse applications. Here we have modelled three systems, BC 6 F 2 H 5 , B 2 C 6 F 4 H 4 and B 2 C 5 F 4 NH 4 . Each of them contain −CF 2 unit (s) with one p z electron on carbon atom exo‐cyclic to the six membered ring. First two systems have 6π electrons and the last one contains 7π electrons in total. Stability of these systems are computationally investigated through Energy Decomposition Analysis (EDA), Molecular Dynamics Simulation, HOMO‐LUMO energy gap and minimum frequency analysis. Aromaticity is quantified through Nucleus Independent Chemical Shift (NICS), Aromatic Stabilization Energy (ASE), Adaptive Natural Density Partitioning (AdNDP) and Multi‐Centre Bond Order (MCBO). Isolated −CF 2 unit can be considered as monoradical entity. From this computational study we observe that the p z electron on exo‐cyclic carbon atom participates in aromatic conjugation which in turn imparts stability to the designed systems. We found that exo‐cyclic conjugation is strong enough to force BC 6 F 2 H 5 and B 2 C 6 F 4 H 4 to be closed shell singlet. On the other hand, B 2 C 5 F 4 NH 4 is in doublet state where formation of aromatic sextet of electrons stabilizes the system, and the extra spin is delocalized over the whole ring and thus forming a stable radical.