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Dynamic and Static Behavior of Intramolecular π–π Interactions in [2.2]‐ and [3.3]Cyclophanes, Elucidated by QTAIM Dual Functional Analysis with QC Calculations
Author(s) -
Matsuiwa Kohei,
Hayashi Satoko,
Nakanishi Waro
Publication year - 2017
Publication title -
chemistryselect
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.437
H-Index - 34
ISSN - 2365-6549
DOI - 10.1002/slct.201602047
Subject(s) - intramolecular force , chemistry , crystallography , stereochemistry , computational chemistry
Dynamic and static nature of the intramolecular π–π interactions between phenyl moieties is elucidated for cyclophanes, 1,4‐C 6 H 4 (C n H 2 n ) 2 C 6 H 4 ‐1’,4’ ( 1 ( n = 2) and 2 ( n = 3)), 1,3,5‐C 6 H 3 (C n H 2 n ) 3 C 6 H 3 ‐1’,3’,5’ ( 3 ( n = 2) and 4 ( n = 3)), C 6 (C n H 2 n ) 6 C 6 ( 5 ( n = 2) and 6 ( n = 3)), and 1’,4’‐C 6 H 4 (C n H 2 n ) 2 ‐1,4‐C 6 H 2 ‐2,5‐(C n H 2 n ) 2 C 6 H 4 ‐2’’,5’’ ( 7 ( n = 2) and 8 ( n = 3)). QTAIM‐DFA (QTAIM dual functional analysis) was applied for the elucidations, together with QC calculations. While the bond paths (BPs) are detected for the intramolecular π–π interactions in 2 , 4 , 6 , and 8 , they are not detected for those in 1 , 5 , and 7 . In the case of 3 , BPs are not detected for those between the bridgehead carbon atoms of ( 1 C, 1’ C), ( 3 C, 3’ C), and ( 5 C, 5’ C), whereas they appear between the non‐bridgehead carbon atoms of ( 2 C, 2’ C), ( 4 C, 4’ C), and ( 6 C, 6’ C). The intramolecular π–π interactions in the cyclophanes are all classified by the pure closed shell interactions. While the intramolecular π–π interactions in 2 , 4 , 6 , and 8 are characterized as the vdW nature, those in 3 are predicted to have the typical HB nature without covalency. The interaction distances between ( 2 C, 2’ C), ( 4 C, 4’ C), and ( 6 C, 6’ C) in 3 are shorter than those connected by BPs, although the distances would not be the key parameters for BPs to appear in cyclophanes.