Structural and computational understanding of weak interactions in "bridge-flipped" isomeric tetrafluoro-bis-benzylideneanilines

• Published in: CrystEngComm 2018, Vol.2 (6), p.716-727
• Main Authors: Dhingra, Shallu, Barman, Dibya Jyoti, Yadav, Hare Ram, Eyyathiyil, Jusaina, Bhowmik, Prasanta, Kaur, Parmeet, Adhikari, Debashis, Roy Choudhury, Angshuman
• Format: Article
• Language: English
• Subjects: Chemical bonds; Computation; Crystal structure; Fluorination; Fluorine; Nitrogen atoms
• ISSN: 1466-8033; 1466-8033
• DOI: 10.1039/c7ce01872j

A structural investigation of the crystal structures of nine pairs of tetra-fluorinated "bridge-flipped" bis-benzylideneanilines has been conducted. The crystal packing patterns were analyzed in terms of intermolecular interactions involving the fluorine and nitrogen atoms ( i.e. , C-H F, F F, C-H π, F π, π π, N π, and C-H N interactions). The stabilization energies offered by these different interactions have been estimated by computational methods using Gaussian 09. Interestingly, strong π π interaction is found only in six exceptional cases, contradicting the general opinion that the π π-stacking synthon is a robust supramolecular synthon. Thus, other intermolecular interactions such as C-F π, C-H π and N π interactions, which are equally strong in stabilizing crystal packing, are also considered to understand the final supramolecular arrangements. These results demonstrate that by changing the orientation of -CH&z.dbd;N-, one can obtain different supramolecular assemblies through various types of intermolecular interactions. The lattice energy was calculated and decomposed into various components using the semi-classical density sums (SCDS) PIXEL method. A detailed analysis of these interactions based on both experimental and computational methods is provided in the manuscript. Structural and computational insights into inter-molecular interactions in isomeric bridge-flipped tetrafluoro-bis-benzylideneanilines.