Helena Čičak

Reaction of Trimethylsilylacetylenes with Antimony Pentafluoride under Matrix Isolation Conditions: Experimental and Computational Study†

Reaction of trimethylsilylacetylenes Me(3)SiC≡CR with SbF(5) in the solid state was investigated using matrix isolation infrared spectroscopy and quantum-mechanical calculations. Two reaction pathways were detected. Replacement of the trimethylsilyl group with SbF(4) produces neutral antimony acetylides F(4)SbC≡CR. Acetylenic bond protonation produces silyl cation 6-R, fully bridged for R = H and SiMe(3). High total charges on the bridging SiMe(3) group and low Me(3)Si-C bond orders to acetylenic moiety, both calculated at the MP4(SDQ)/6-311G(d,p) level of theory, indicate high silyl cation character of these species.

6-Iodo-2-methyl-1,3-benzothia-zole.

The title compound, C8H6INS, is essentially planar, the largest deviation from the mean plane being for the I atom [0.075 (3) Å]. The crystal structure is mainly stabilized by intermolecular C—I⋯N halogen bonds, forming zigzag supramolecular chains in [10]. Relatively short off-set π–π contacts [centroid–centroid distance = 3.758 (2) Å] between the thiazole rings of inversion-related molecules link neighbouring chains and provide the secondary interactions for building the crystal structure.