Complexation of n SO2 molecules (n = 1, 2, 3) with formaldehyde and thioformaldehyde

Abstract

Ab initio and density functional theory calculations are used to examine complexes formed between H2CO and H2CS with 1, 2, and 3 molecules of SO2. The nature of the interactions is probed by a variety of means, including electrostatic potentials, natural bond orbital, atoms in molecules, energy decomposition, and electron density redistribution maps. The dimers are relatively strongly bound, with interaction energies exceeding 5 kcal/mol. The structures are cyclic, containing both a O/S⋯S chalcogen bond and a CH⋯O H-bond. Addition of a second SO2 molecule leads to a variety of heterotrimer structures, most of which resemble the original dimer, where the second SO2 molecule engages in a chalcogen bond with the first SO2, and a C⋯O attraction with the H2CX. Some cooperativity is apparent in the trimers and tetramers, with an attractive three-body interaction energy and shortened intermolecular distances.

An exploration of the ozone dimer potential energy surface

“…Electrostatic attractions are typically supplemented by charge transfer from the lone pair(s) of one atom into the σ * or π * antibonding [29][30][31][32] orbital of the partner molecule. This same idea extends beyond chalcogen atoms, to other electronegative atoms, notably members of the halogen [33][34][35][36][37][38] and pnicogen [39][40][41][42][43][44] families, and there are very recent works that suggest that even the less electronegative C group of the periodic table can engage in very similar bonding interactions, known as "tetrel bonds."…”

Strongly bound noncovalent (SO3)n:H2CO complexes (n = 1, 2)

“…An earlier study of the heterodimer of SO 2 with H 2 CO found an equilibrium structure very much like A1 here. 38 The SÁ Á ÁO distance was longer by 0.354 Å, but R(OÁ Á ÁH) nearly the same. Consistent with the longer R(SÁ Á ÁO), the interaction energy of this dimer was 5.42 kcal mol À1 at the CCSD(T)/aug-cc-pVTZ//MP2/augcc-pVDZ level, only half that of A1.…”

Ab initio and DFT studies of the interaction between carbonyl and thiocarbonyl groups: the role of S···O chalcogen bonds

“…In the H 2 C=S···O 2 S complex, a similar distance of 3.198 Å has been predicted [33]. In contrast with the complexes between SCS and Cl − [35], OH 2 [37] or OHX(X = Cl, Br) [38], in most of the systems investigated here, the C=S···O bond is not linear.…”

“…In the complex between SO 2 and H 2 C=S, for example, a charge transfer from a SO 2 oxygen lone pair to the π*(C=S) antibonding orbital of H 2 C=S has been predicted [33]. The potential interactions of the nitrile halides XNO 2 with NH 3 as electron donor in the σ-and π-hole regions have been investigated [34].…”