Experimental evidence for ‘carbon bonding’ in the solid state from charge density analysis

Abstract

The validity of the newly proposed 'carbon bonding', an interaction where a carbon atom acts as an electrophilic site towards a variety of nucleophiles, has been investigated in the solid state. X-ray charge density analysis provides experimental evidence for this hitherto unexplored interaction and unravels its nature and strength.

RCH3···O Interactions in Biological Systems: Are They Trifurcated H-Bonds or Noncovalent Carbon Bonds?

“…They demonstrated that the carbon atom in fact could act as an electrophilic center which can non-covalently bond with electron-rich entities leading to noncovalent carbon bonding, following a nomenclature analogous to other σ-hole interactions [7][8][9][10][11][12][13][14][15][16][17]. The theoretical predictions were confirmed experimentally by Guru Row's group [42], thus validating the existence of this type of bonding by means of X-ray charge density analysis. Electron density topologies in two prototypical crystal structures with potential carbon bonding motifs (R3N + -CH3···O/Cl) were reported and revealed two distinct features of bond paths.…”

Interplay between tetrel bonding and hydrogen bonding interactions in complexes involving F2XO (X=C and Si) and HCN

“…Its formation is attributed to a positive electrostatic potential on the group IV atomic surface [23]. On the other hand, the experimental evidence for its existence was given with charge density analysis for a large number of known crystal structures [24]. The importance of tetrel-bonding in cyclobutane rings was demonstrated by combining high level theoretical calculations and the Cambridge Structural Database (CSD) analysis, showing that tetrel-bonding interactions are quite common in nitro-substituted cubanes [25].…”

Nature of Noncovalent Carbon‐Bonding Interactions Derived from Experimental Charge‐Density Analysis

“…[30][31][32] In an sp 3 -hybridized electron-deficient C atom, there is only limited space available for an electron-rich guest molecule to nest itself. [31,32] To exem-plify this, we have represented in Figure 1 (right) the MEP sur- Figure 1.face of 1,1,2,2-tetracyanoethane (staggered conformation). The s hole is small and it is surrounded by negative belts, which hinder interactions with any concentration of negative charge (lone pair or anion).…”

“…[6,[19][20][21][22] More recently, s-hole complexes with atoms of group IV, the tetrel (Tr) atoms, have been described, [24][25][26][27][28][29] and mostly focus on the heavier Tr atoms as tetrel-bond donors, leaving noncovalent carbon bonding much less studied. [30][31][32] In an sp 3 -hybridized electron-deficient C atom, there is only limited space available for an electron-rich guest molecule to nest itself. [31,32] To exem-plify this, we have represented in Figure 1 (right) the MEP sur- Figure 1.…”

“…[30][31][32] In an sp 3 -hybridized electron-deficient C atom, there is only limited space available for an electron-rich guest molecule to nest itself. [31,32] To exem-plify this, we have represented in Figure 1 (right) the MEP sur- Figure 1.…”