Bonding Trends in Lewis Acid Adducts of S 4 N 4 – X‐ray Structure of TeCl 4 ·S 4 N 4

Tetrasulfur tetranitride and tellurium tetrachloride react in dichloromethane to form a 1:1 adduct TeCl 4 · S 4 N 4 ( 1 ). The crystal structure of 1 shows that TeCl 4 is bonded to the S 4 N 4 ring through a Te–N linkage. As a consequence, the transannular S ··· S bonds in S 4 N 4 are broken and the molecule assumes an open, monocyclic conformation. The Te–N bond of 2.16(1) Å is slightly longer than the single bond. The S–N bonds span a range of 1.55(1)–1.67(1) Å. The adduct 1 was also characterized by mass spectrometry and Raman spectroscopy. The bonding and spectroscopic properties of 1 are compared by DFT calculations at the B3PW91/(RLC ECP) level of theory with those of BF 3 · S 4 N 4 ( 2 ), SO 3 · S 4 N 4 ( 3 ), AsF 5 · S 4 N 4 ( 4 ), SbCl 5 · S 4 N 4 ( 5 ) for which experimental structural information is available. The structural and bonding trends in TeF 4 · S 4 N 4 ( 6 ), TeBr 4 · S 4 N 4 ( 7 ), and SeX 4 · S 4 N 4 [X = F ( 8 ), Cl ( 9 ), Br ( 10 )] are also discussed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)