Mercury complexes with thiacrowns: The crystal structure of bis(1,4,7-trithiacyclodecane)mercury(II) hexafluorophosphate

We report the synthesis, crystal structure, and NMR spectroscopy for the mercury(II) complex with the crown thioether 1,4,7-trithiacyclodecane (10S3), bis(1,4,7-trithiacyclodecane)mercury(II) hexafluorophosphate (1). The 10S3 ligand coordinates in tridentate fashion and readily forms a distorted bis octahedral complex, an unusual coordination geometry for Hg(II). The crystal structure shows the two 10S3 ligands arranged in a trans or anti fashion around the mercury center, yielding the meso stereoisomer. Bond distances and angles are very comparable to those found in the structure of the perchlorate salt of the complex cation although the hexafluorophosphate salt shows slightly longer and more varied Hg-S distances (2.623(2), 2.708(2), 2.784(2) Å) with a tetragonal elongation. The ¹⁹⁹Hg{¹H} NMR spectrum exhibits a single resonance with a chemical shift at -596 ppm consistent with a hexakis(thioether) coordination environment around the mercury center. Crystal data for 1: C2/c, a = 19.184(3) Å, b = 15.235(2) Å, c = 11.3791(15) Å, β = 123.358(2)°, V = 2777.9(6) ų, Z = 4.