The nature of the C–Br⋯Br–C intermolecular interactions found in molecular crystals: a general theoretical-database study

CrystEngComm ◽  
2015 ◽  
Vol 17 (17) ◽  
pp. 3354-3365 ◽  
Author(s):  
Marçal Capdevila-Cortada ◽  
Juan J. Novoa

The properties of C–Br⋯Br–C interactions have been determined by doing MP2 theoretical calculations on model dimers and on dimers taken from the Cambridge Structural Database (presenting Br⋯Br distances within the 3.0 to 4.5 Å range).

Author(s):  
Michał Kaźmierczak ◽  
Andrzej Katrusiak

The survey of the shortest contacts in structures deposited in the Cambridge Structural Database shows that chalcogen...halogen, halogen...halogen and chalcogen...chalcogen interactions can compete as cohesion forces in molecular crystals. The smallest parameter δ (defined as the interatomic distance minus the sum of relevant van der Waals radii) for Ch...X contacts between chalcogens (Ch: S, Se) and halogens (X: F, Cl, Br, I) is present only in 0.86% out of 30 766 deposited structures containing these atoms. Thus, in less than 1% of these structures can the Ch...X forces be considered as the main type of cohesion forces responsible for the molecular arrangement. Among the 263 structures with the shortest Ch...X contact, there are four crystals where no contacts shorter than the sums of van der Waals radii are present (so-called loose crystals). The smallest δ criterion has been used for distinguishing between the bonding (covalent bond) and non-bonding contacts and for validating the structural models of crystals.


1996 ◽  
Vol 52 (4) ◽  
pp. 720-727 ◽  
Author(s):  
P. Bombicz ◽  
M. Czugler ◽  
A. Kálmán ◽  
I. Kapovits

The bonding and conformational characteristics of bissulfonylamides and analogous imides are compared. Structures (44 altogether) containing R—SO2—NQ—SO2—R′ units were retrieved from the Cambridge Structural Database. They are either neutral (Q-H, alkyl or aryl groups, hereto atoms such as O and S) or charged (Q = e−) and bearing the functions R, R′ = Me, Et or Ph, respectively. The principal conformations of the —SO2—NQ—SO2— bridge (open versus folded) are represented by sodium dibenzenesulfonamide (BSULFA) and dibenzenesulfonimide (NABSUF). In addition to the compounds possessing Q = alkyl or aryl functions, complexes with N-metal bonds could clearly be distinguished. The dominant forms of SVI—X (X = O, N C) bonds are characterized and correlated with the bond angles formed around the S atoms. The marked difference between the archetypes of the S—N bonds (i.e. nitrogen charged or neutral) indicated that the interdependence of the S—X bonds, i.e. the size and the shape of the SVI[O,O′,N,C] tetrahedra, are principally governed by the environment of the N atoms. The conformation symmetry and dissymmetry of the charged and neutral —SO2—NQ—SO2— moieties are described in terms of the internal rotations about the bonds in the R—S—N—S—R′ fragment.


2020 ◽  
Vol 22 (22) ◽  
pp. 12757-12765
Author(s):  
Bartomeu Galmés ◽  
Jaume Adrover ◽  
Giancarlo Terraneo ◽  
Antonio Frontera ◽  
Giuseppe Resnati

A search in the Cambridge Structural Database and theoretical calculations (UPBE0-D3/def2-TZVP level of theory) show the existence and relevance of substituent effects on the strength of radical⋯radical chalcogen bonding interactions.


Crystals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 460 ◽  
Author(s):  
Sławomir J. Grabowski

The BF4− anion is characterised by weak Lewis base properties; it is usually classified as a “non-coordinating anion”. The searches through the Cambridge Structural Database (CSD) were performed and it was found that the BF4− anion often occurs in crystal structures and it is involved in numerous intermolecular interactions; hydrogen bonds are the majority of them. The hydrogen bonds involving the BF4− anion as a proton acceptor are closer to linearity with the increase of the strength of interaction that is in line with the tendency known for other hydrogen bonds. However, even for short contacts between the proton and the Lewis base centre, slight deviations from linearity occur. The MP2/aug-cc-pVTZ calculations on the BF4−…HCN complex and on the BF4−…(HCN)4 cluster were also carried out to characterise corresponding C-H…F hydrogen bonds; such interactions often occur in crystal structures.


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