Matrix-isolation infrared studies of 1:1 molecular complexes containing chloroform (CHCl3) and Lewis bases: Seamless transition from blue-shifted to red-shifted hydrogen bonds

Abstract

The infrared spectra of molecular complexes containing chloroform (CHCl(3)) and Lewis bases (N(2), CO, H(2)O, and CH(3)CN) have been observed in an Ar matrix, and vibrational peaks for the 1:1 complexes have been assigned. The C-H stretching band of chloroform in the complexes showed a seamless transition from a blue shift (for N(2) and CO) to a red shift (H(2)O and CH(3)CN), in accord with the proton affinity of the base molecules. Density functional calculations predicted that the C-H··(σ-type lone pair) isomer is the most stable, which is consistent with the observed vibrational peak shift upon complex formation. The underlying mechanisms of the C-H hydrogen bond were explored using the topological properties of the electronic charge density and natural orbital analyses.

Infrared spectra of formic acid clusters in noble gas matrices

“…The aim of the present study is to provide spectroscopic data for the large formic acid clusters (HCOOH) n (n > 3) by using matrixisolation technique, and to compare them with theoretically simulated spectra for gaining structural information on these species, as has been done previously [28][29][30][31][32][33][34].…”

Controlling the Dual‐Emission Character of Aryl‐Modified o‐Carboranes by Intramolecular CH⋅⋅⋅O Interaction Sites

“…While general hydrogen bonds shift the band to a smaller energy region, [26] the opposite shift is also known as an "improper hydrogen bond," which is sometimes observed in CH•••X hydrogen bonding systems. [31] From these results, the C cage H•••O interaction should be formed both in solution and solid states. Finally, atoms-in-molecules (AIM) analysis [32] was conducted to estimate C cage H•••O binding energies.…”

Medium-Dependent Crossover from the Red to Blue Shift of the Donor’s Stretching Fundamental in the Binary Hydrogen-Bonded Complexes of CDCl3 with Ethers and Ketones

“…For example, in the binary complexes of CHCl 3 with acetone-d 6 and water prepared in a matrix, the ν C−H band of the donor molecule undergoes red shifts of 38 and 14 cm −1 , respectively. 27,28 Similar studies with CDCl 3 as a donor reveal red shifts of 27, 10, and 111 cm −1 of the ν C−D band in the binary complexes with acetone, water, and trimethylamine, respectively. 27,28 On the other hand, in many of the cases studied, H-bonded complexes involving C−H/C−D donors display blue shifting of ν C−H /ν C−D frequencies.…”