Revisiting electronic nature and geometric parameters of cyclophanes and their relation with stability – DFT, QTAIM and NCI study

Publication date: Available online 12 May 2018 Source:Computational and Theoretical Chemistry Author(s): Caio L. Firme, Diógenes M. Araújo Cyclophanes have several geometric restrictions in their structure due to formation of a closed circuit involving benzenoid rings and aliphatic bridges and they cause instability. We have chosen a wider variety of ciclophanes for the ωB97XD analysis of geometry and thermodynamic data. More detailed geometric parameters have been used in this work such as the deviation from planarity equations and benzenoid CC bond RMSD. Seventy percent of cyclophanes’ stability is derived from benzenoid geometric parameters. Other twenty percent of cyclophanes’ stability is related to one alkyl bridge geometric parameter and two electronic parameters (global aromaticity according to FLU or D2BIA and number of intramolecular interactions according to QTAIM). In addition, no linear relation between aromaticity and the geometrical parameters was obtained and then aromaticity in cyclophanes cannot be simply evaluated from their benzenoid geometric parameters. Aromaticity of cyclophanes was analyzed locally and globally for each cyclophane using FLU, HOMA, ELF, NICS and D2BIA aromaticity indexes while intramolecular interactions were analyzed by means of QTAIM and NCI. Graphical abstract
Source: Computational and Theoretical Chemistry - Category: Chemistry Source Type: research
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