Strong and weak effects caused by non covalent interactions between chloroform and selected electron donor molecules

Abstract

The FTIR spectra of chloroform (Cl(3)CH) in mixtures with various electron donors (B = CH(3)CCH, HCCH, NCCD(3), ClCD(3) and CO) have been studied in liquefied Kr. Spectroscopic evidence of weak H-bond formation has been found. The relative stability of some complexes has been evaluated from temperature studies of integrated intensities of vibrational bands attributed to monomer and complex species. A weak red shift of the stretching vibration of chloroform involved in H-bonding with CH(3)CCH and HCCH having π-electron area was observed. However, in the case of interactions with NCCD(3) and CO, a weak blue shift was detected. In most of the cases, a noticeable increase in the integrated intensity of the CH stretching band was found. Ab initio MP2/6-311++G(2d,2p) a priori counterpoise corrected calculations have been performed for a series of Cl(3)CH and B. Stationary points at the potential energy surface were examined and the structures related to the real minima have been found. The calculations reproduce the majority of experimental results. It has been found that the commonly used correlation between the frequency shift of the CH stretching vibration of the proton donor subunit and the change in CH bond length can fail in the case of the complexes characterized by a weak frequency shift effect.

Blue- and Red-Shifting Hydrogen Bonding: A Gas Phase FTIR and Ab Initio Study of RR′CO···DCCl3 and RR′S···DCCl3 Complexes

“…There are other experimental and theoretical reports where blue-shifting H-bonds are accompanied by a jump in the band intensity. 7,51 The H-bond acceptor ability (which is proportional to the binding energy of the complex) versus change in C−D bond length (ΔR), X−H bond length, and C−D stretching frequencies (Δν) of the two series of H-bonded complexes we studied has been summarized in a simple qualitative diagram (Figure 4) similar to the one put forward by Joseph et al 13 RR′CO, which shows blue-shifting H-bonds. In the RSR′ series, the H-bonding starts with a blue shift and then crosses over to the other side of the schematic plot in Figure 4b and becomes red-shifted.…”

Importance of water and intramolecular interaction governs substantial blue shift of Csp2–H stretching frequency in complexes between chalcogenoaldehydes and water

“…24 So far, a large variety of BSHB with the involvement of C-H bond as proton donor in C-H/O/N/halogen/p H-bonds, of which the C-H/O/N Hbonds are most abundantly reported, have been recorded experimentally using IR and Raman spectroscopy. [25][26][27][28][29][30][31][32][33] More recently, in 2019, a very slight C-H blue-shi of 8.7 cm À1 was even observed by Fourier transform IR spectroscopy for the C-H/N H-bond in the binary Cl 3 CH/NCCH 3 complex. 34 Similar to covalent C sp 3 -H bonds (C sp 3 refers to the tetrahedral carbon), the stretching frequency blue-shis were recently observed in C sp 2-H bonds upon the formation of hydrogenbonded complexes to a larger extent.…”

Theoretical Aspects of Nonconventional Hydrogen Bonds in the Complexes of Aldehydes and Hydrogen Chalcogenides

“…In 1999, an increase of C–H stretching frequency was reported in the complex between chloroform and fluorobenzene by using double-resonance IR ion-depletion spectroscopy . In addition, a surprising shortening of the C–H bond was found in C–H...O/N/halogen/π H-bonds. − The BSHB is often reported for H-bond complexes formed between various proton acceptors and the proton donor C sp3 –H (C sp3 refers to the tetrahedral hybridized carbon in the molecule). ,, For example, complexation between methane, fluoroform, chloroform, bromoform, and iodoform on the one hand and water, benzene, fluorobenzene, acetylene, and ethylene ,,, on the other hand leads to a C–H bond contraction.…”