Unexpected Formation of the Iodobismuthate Salt (C 14 H 15 S 2 N 2 ) 2 (C 9 H 10 SN) 2 [Bi 4 I 16 ] upon Reaction of the Unsaturated Ligand Z -PySCH 2 CH=CHCH 2 SPy with BiI 3

The olefinic dithioether ( Z )-1,4-bis(pyridin-2-ylthio)but-2-ene Z -PyS(CH 2 CH=CHCH 2 )SPy ( L ) was prepared by the treatment of cis -ClCH 2 CH=CHCH 2 Cl with in situ generated potassium pyridine-2-thiolate Py-SK and analyzed by IR and NMR spectroscopy. To investigate the chemistry of polynuclear iodobismuthate complexes, two equivalents of BiI 3 were reacted with L in the MeOH solution to afford the anionic tetranuclear title compound (C 14 H 15 S 2 N 2 ) 2 (C 9 H 10 SN) 2 [Bi 4 I 116 ] with a N -protonated ( Z )-1,4-bis(pyridin-2-ylthio)but-2-ene as a counterion. Compound 1 was characterized by IR and UV spectroscopy; the formation of a tetranuclear framework was ascertained by a single-crystal X-ray diffraction study performed at 100 K. Furthermore, an unusual Bi(III)-meditated cyclization of one Z -PyS(CH 2 CH=CHCH 2 )SPy ligand occurred, affording the bicyclic pyridinium salt 3-vinyl-2,3-dihydrothiazolo[3,2- a ]pyridinium bearing a terminal vinyl group, compensating the second negative charge of the Bi 4 I 16 4− cluster anion. The SCXRD characterization was completed by a Hirshfeld surface analysis, revealing some secondary interactions occurring in the crystal.