Sizing the Ubbelohde effect: the rotational spectrum of a tert-butylalcohol dimer

Abstract

The H → D isotopic substitution of the hydroxylic hydrogen participating in the O-H···O hydrogen bond in the tert-butylalcohol dimer produces an increase of the B and C rotational constants, according to the shrinkage of the OO distance of about 7 mÅ, underlying and sizing the associated Ubbelohde effect.

Hydrogen bond competition in the ethanol–methanol dimer

“…B0.9 Å in the t-butylalcohol dimer. 26 Thus, the B0.6 Å difference between the ab initio and experimental Kraitchman |a| coordinates that we observe on the methanol hydrogen, is likely due to this effect. Besides the Ubbelohde effect, the errors on the coordinates of this hydrogen are high, due to its vicinity to the center of mass.…”

How CO2 Interacts with Carboxylic Acids: A Rotational Study of Formic Acid–CO2

“…Analysis of the shifts of the planar moment of inertia upon carboxyl deuteration (Table 3) shows that the predicted Δ M aa is considerably higher than experimentally observed. This always happens when the shortening of the hydrogen bond distance takes place upon the OH→OD substitution, corresponding to different zero‐point vibrational energy values 48. In order to take this effect into account, a decrease in the O6⋅⋅⋅O4 intermolecular distance was introduced in the fit when considering the rotational constants of the carboxyl deuterated species.…”

Simple models for the quick estimation of ground state hydrogen tunneling splittings in alcohols and other compounds

“…While for many alcohols the anharmonicity of the OH oscillator appears to be very similar, 111 this is not the case for hydrogen bonded systems. Here, geometrical alterations, such as the (reverse) Ubbelohde effect, 112,113 can lead to counter-intuitive changes, such as an increase of the splitting upon deuteration. 2,114 Even a switch between qualitatively different structures was reported.…”