S−H…O and O−H…O Hydrogen Bonds‐Comparison of Dimers of Thiocarboxylic and Carboxylic Acids

Abstract

ωB97‐XD/aug‐cc‐pVTZ calculations were performed on dimers of selected thiocarboxylic acids and on analogous carboxylic acids. The sample of calculated thiocarboxylic acids is an extension of the Cambridge Structural Database search that contains only a few such structures. The Natural Bond Orbital (NBO) method, Symmetry‐Adapted Perturbation Theory (SAPT) approach, Non‐Covalent Interaction (NCI) method and Quantum Theory of Atoms in Molecules (QTAIM) were applied additionally to analyse interactions in dimers of thiocarboxylic and carboxylic acids. The insights into crystal structures as well as into results of calculations show that the formation of S−H…O hydrogen bonds between molecules of thiocarboxylic acids is steered by the same mechanisms as the formation of much stronger O−H…O hydrogen bonds in carboxylic acids. The intramolecular O−H…O and C−H…S hydrogen bonds occurring in few considered structures are also analysed.

Observation of an Unusually Large IR Red-Shift in an Unconventional S–H···S Hydrogen-Bond

“…On the other hand, detailed studies of the hydrogen-bonds involving an unconventional hydrogen-bond donor are mostly limited to C–H···Y hydrogen-bonds, where Y is generally a conventional hydrogen-bond acceptor (O, N, etc. ), and this hydrogen-bond has been established as a weak non-covalent interaction. ,− Nevertheless, there are a few spectroscopic studies in the literature involving S as a hydrogen-bond donor with a π-electron cloud as well as N and O acting as hydrogen-bond acceptors. − These reports suggest that S, in general, is a weak hydrogen-bond donor as compared to N and O.…”

Coexistence of Intra- and Intermolecular Hydrogen Bonds: Salicylic Acid and Salicylamide and Their Thiol Counterparts

“…The search with the same conditions performed to find dithiocarboxylic acids, i.e., structures containing the −CS 2 H group, led to the only one structure, the crystal structure of trithiocarbonic acid. 20 …”

“…It seems that dimers of carboxylic acids are the most often occurring intermolecular RAHBs since other systems linked by such interactions as, for example, amide dimers, amide–amidine couplings, thiocarboxylic acid dimers, or DNA base pairs are not so common. The Cambridge Structural Database (CSD) , searches were performed in one of the recent studies, and 4722 cases of carboxylic acid dimers linked by two O–H···O hydrogen bonds occur, while the analogues search for thiocarboxylic acids leads to three dimers; both searches were performed for conditions to find accurate crystal structures without errors. The search with the same conditions performed to find dithiocarboxylic acids, i.e., structures containing the −CS 2 H group, led to the only one structure, the crystal structure of trithiocarbonic acid …”

“…The Cambridge Structural Database (CSD) , searches were performed in one of the recent studies, and 4722 cases of carboxylic acid dimers linked by two O–H···O hydrogen bonds occur, while the analogues search for thiocarboxylic acids leads to three dimers; both searches were performed for conditions to find accurate crystal structures without errors. The search with the same conditions performed to find dithiocarboxylic acids, i.e., structures containing the −CS 2 H group, led to the only one structure, the crystal structure of trithiocarbonic acid …”

“…The search with the same conditions performed to find dithiocarboxylic acids, i.e., structures containing the −CS 2 H group, led to the only one structure, the crystal structure of trithiocarbonic acid. 20 The aim of this study is to analyze o-substituted derivatives of carboxylic acids, particularly the interrelation between intermolecular and intramolecular hydrogen bonds. In dimers of these species linked by carboxylic groups the S(6) and R 2 2 (8) motifs described earlier here occur.…”