Structure of the trimethylamine-sulfur dioxide complex

Computational Studies on the Sulfur Dioxide Absorption by Organic Lewis Bases

“…The energy-minimum was obtained at 1.90 Å with a gradual stabilization after which the energy increased abruptly (Figure 1a). The overall energy profile indicates that the absorption reaction for TMA is a one-step reaction forming N-S bonding with no transition state, which was also observed for the previous reports on TMA-SO 2 , 7 and NH 3 -BF 3 . 11 Similar trends have been observed for the other amines, TEA, MEA and pyridine with the optimized N-S distances of 2-2.3 Å (Figures 1b, 1c and 1d).…”

“…11 The N-S distances of TMA-and pyridine-SO 2 complexes are wellmatched to the experimental values in gas phases (2.26, and 2.61 Å, respectively). 7,10 These values become smaller by about 0.29 Å with maintaining overall conformations when PCM models were applied. The calculated binding energy of the TMA-SO 2 complex (-9.07 kcal/mol) in a gas phase is very close to the experimental value (-9.1 kcal/mol).…”

“…4 Various sulfur dioxide complexes at molecular level have been extensively studied by Kuczkowski and coworkers. [7][8][9][10] They classified sulfur dioxide complexes according to the types of interactions into charge-transfer complexes, van der Waals complexes, and hydrogen-bonded complexes. 10 Gas phase complexes were investigated by microwave spectroscopy and ab initio calculations, and solid state structures by X-ray crystallography.…”

“…However, it is noticeable that TMAand DMA-SO 2 (TMA = trimethylamine, DMA = dimethylaine) complexes having 2.046(4), and 2.003 (12) Å for d(N-S)s in solid, respectively, are only about 0.25 Å contraction from those in gas phases. 7,11 Considering that the SO 2 complexes have been studied for a long time, it is our surprise that there have been yet no theoretical investigations on the SO 2 complexes by the viewpoint of the SO 2 removal. Only chemical engineers have been interested in this issue, and studied the SO 2 removal process experimentally.…”

The Development and Application of Sulfur Dioxide Surrogates in Synthetic Organic Chemistry

“…The overwhelming majority of the literature published has focussed on the investigation of the structure of these complexes, rather than their applications, with IR, NMR, microwave, Raman, X-ray, and computational analysis all being applied. [40][41][42][43][44][45][46] Although these complexes have been shown to have indirect uses, such as determining the concentration of SO 2 in solution using a metalloporphoryin assay, [47] and as gas scrubbers, [48,49] reports of the use of the isolated complexes as sulfur dioxide surrogates were until recently scarce. Olah et al published a series of dehydrative and reductive transformations utilising the trimethylamine and triethylamine complexes in the late 1970s (Scheme 9) [50][51][52][53][54] as well as a more recent report documenting a polyvinylpyridine complex as a solid-supported acid catalyst for a Strecker-type reaction.…”