Conformational Equilibria of 2‐Methoxypyridine⋅⋅⋅CO₂: Cooperative and Competitive Tetrel and Weak Hydrogen Bonds

Abstract

The rotational spectrum of 2‐methoxypyridine⋅⋅⋅CO2 was recorded and analysed employing a cavity‐based Fourier transform microwave spectrometer, complemented with quantum chemical calculations which predicted three possible isomers within energies less than 1000 cm−1. The two most stable isomers were observed in the pulsed jet, which are stabilized by a network of C⋅⋅⋅N/O tetrel and C−H⋅⋅⋅O weak hydrogen bonds. The relative population ratio of the two detected isomers was estimated to be NI/NII≈2.5. The competition and cooperation of the present non‐covalent interactions in both isomers are discussed within the framework of Bader's quantum theory of atoms in molecules and Johnson's non‐covalent interaction analyses. The study shows, that when looking for CO2 adsorbents, one might prefer candidates with multiple interactions in one site over candidates with few but strong interactions.

Fluorination effects probed in 4-fluoroacetophenone and its monohydrate

“…This discrepancy is probably attributed to the relaxation of some fraction of isomer II to isomer I during ultrasonic jet expansion, resulting in more abundance of isomer I. 56 Based on the Kraitchman's equation, the r s substitution coordinates of the water oxygen were calculated and reported in Table S25 (ESI †), which are largely consistent with the theoretical calculation. Similar to 4FAP monomer, the vibrotational contributions were also calculated for all isotopologues of 4FAP-H 2 O at the B3LYP-D3(BJ)/6-311++G(d,p) level.…”

“…This discrepancy is probably attributed to the relaxation of some fraction of isomer II to isomer I during ultrasonic jet expansion, resulting in more abundance of isomer I. 56…”

Conformational equilibria in acrolein–CO2: the crucial contribution of n → π* interactions unveiled by rotational spectroscopy

“…8 There has been a rigorous effort to qualitatively and quantitatively decipher the non-covalent interactions (NCIs) between CO 2 and partner molecules, through rotational spectroscopic investigations complemented by quantum chemical calculations. [9][10][11][12][13][14][15][16][17][18][19][20] In complexes with strong proton donors such as HF 9 and HCl, 10 CO 2 is predominantly involved in F/Cl-HÁ Á ÁOQC hydrogen bonds (HBs) within a linear form. Complexes formed with carboxylic acids (formic acid 11 and acrylic acid 12 ), which also act as strong proton donors, whose complexes with CO 2 , indeed, are stabilized by pronounced O-HÁ Á ÁOQC HBs.…”

Interaction Types in C6H5(CH2)nOH–CO2 (n = 0–4) Determined by the Length of the Side Alkyl Chain

“…There has been a long-lasting effort to qualitatively and quantitatively understand the intermolecular interactions of CO 2 through rotational spectroscopic investigations. − With the oxygen lone pairs and a π* antibonding orbital (or π-hole) associated with the carbon atom, CO 2 can act as an electron donor or an electron acceptor, interacting with different partner molecules . As a rough conclusion, the interaction preference of CO 2 with linear HX (X = F, Cl, Br, or CN) mainly depends on the electronegativity of X (F > Cl > CN > Br).…”

“…38 the oxygen lone pairs and a π* antibonding orbital (or π-hole) associated with the carbon atom, CO 2 can act as an electron donor or an electron acceptor, interacting with different partner molecules. 38 As a rough conclusion, the interaction preference of CO 2 with linear HX (X = F, Cl, Br, or CN) mainly depends on the electronegativity of X (F > Cl > CN > Br). With HF 39 and HCl, 40 42 With HCN, both linear (HB) and T-shaped (TB) configurations have been experimentally observed, with the latter being more stable.…”