Continuum in the X‐Z‐‐‐Y weak bonds: Z= main group elements

Abstract

The Continuum in the variation of the X-Z bond length change from blue-shifting to red-shifting through zero- shifting in the X-Z---Y complex is inevitable. This has been analyzed by ab-initio molecular orbital calculations using Z= Hydrogen, Halogens, Chalcogens, and Pnicogens as prototypical examples. Our analysis revealed that, the competition between negative hyperconjugation within the donor (X-Z) molecule and Charge Transfer (CT) from the acceptor (Y) molecule is the primary reason for the X-Z bond length change. Here, we report that, the proper tuning of X- and Y-group for a particular Z- can change the blue-shifting nature of X-Z bond to zero-shifting and further to red-shifting. This observation led to the proposal of a continuum in the variation of the X-Z bond length during the formation of X-Z---Y complex. The varying number of orbitals and electrons available around the Z-atom differentiates various classes of weak interactions and leads to interactions dramatically different from the H-Bond. Our explanations based on the model of anti-bonding orbitals can be transferred from one class of weak interactions to another. We further take the idea of continuum to the nature of chemical bonding in general.

Looking Inside the Intramolecular C−H∙∙∙O Hydrogen Bond in Lactams Derived from α-Methylbenzylamine

“…The red and blue shifting of hydrogen bonds is attributed to a pair of correlated effects; namely, the n (Y) →σ* X−H orbital interaction and rehybridization at the X atom with a concomitant polarization of the X−H bond [ 27 , 28 , 29 , 30 ]. According to Alabugin et al [ 27 ], as the electronegativity of Z increases (Z = CH 3 , NH 2 , OH, F), so does the polarization of a C−Z bond, whereas the s-character in the carbon-centered hybrid atomic orbital of the C−Z bond is reduced.…”

Implications of monomer deformation for tetrel and pnicogen bonds

“…[1][2][3] The introduction 4 and further expansion of the application of interactions parallel to the HB triggered increased interest in the scientific community. [5][6][7][8][9][10][11] In particular, these new types of bonds replaced the bridging proton by halogen, [12][13][14][15] chalcogen, [16][17][18][19] pnicogen [20][21][22][23] and tetrel [24][25][26][27] atoms and these bonds were named accordingly.…”

Reliable Comparison of Pnicogen, Chalcogen, and Halogen Bonds in Complexes of 6-OXF2-Fulvene (X = As, Sb, Se, Te, Be, I) With Three Electron Donors

“…Of course, interest in other intermolecular interactions has been growing rapidly. These new types of intermolecular interactions were named for the type of atom that replaces the bridging proton in the HB, and these atoms include aerogen (Bauzá and Frontera, 2015a,b,c), halogen (Desiraju et al, 2013;Cavallo et al, 2016;Terraneo and Resnati, 2017), chalcogen (Azofra et al, 2015;Nziko and Scheiner, 2015;Nayak et al, 2017), pnicogen (Bauzá et al, 2016;Joy et al, 2016;Sánchez-Sanz et al, 2016), and tetrel (Grabowski, 2014a;Mani and Arunan, 2014;Li et al, 2015) atoms. Scientists have tried to provide a consistent explanation for the origin of these different intermolecular interactions.…”