Synthesis, Characterization and Molecular Structures of someBismuth(III) Complexes with Thiosemicarbazones andDithiocarbazonic Acid Methylester Derivatives with Activityagainst Helicobacter Pylori

The reactions of bismuth(III) nitrate pentahydrate and bismuth(III) chloride with heterocyclic thiosemicarbazones and derivatives of dithiocarbazonic acid methylester were used to synthesize the respective bismuth(III) complexes, which could be divided into five groups D‐H because of their stoichiometrical properties and their molecular structures. The molecular structure and the near coordination sphere of the bismuth(III) central atom of four representative compounds were determined by single‐crystal X‐ray studies. Bis[1‐azepanyl‐4‐(2‐pyridyl)‐2,3‐diazapenta‐1,3‐diene‐1‐thiolato‐N′,N 3 ,S]bismuth(III) nitrate (5) belongs to group D. The two tridentate ligands and the nitrate ion surround the bismuth atom. The best description of the coordination sphere appears to be that of a distorted trigonal dodecahedron with one position occupied by the lone pair of the bismuth atom. Bis[1‐azepanyl‐4‐(2‐thienyl)‐2,3‐diazapenta‐1,3‐diene‐1‐thiolato‐N 3 ,S]bismuth(III) nitrate (9) is assigned to complex type E. Here, two deprotonated ligand molecules are coordinated to the bismuth(III) central atom as bidentate ligands. The structure of this complex can best be described as a distorted trigonal antiprism with a five‐coordinated central atom. The two triangular faces are formed by the atoms S(4), N(6), O(11) and S(3), N(4) and the lone pair of the central atom. The two chelate rings are almost perpendicular to each other. Complex molecules of group F form dimeric units with bichloro‐bridged bismuth atoms. The structure of di‐ μ ‐chlorobis[1‐azepanyl‐4‐(2‐pyridyl)‐2,3‐diazapenta‐1,3‐diene‐1‐thiolato‐N′,N 3 ,S‐chloro]dibismuth(III) (15) can be described as two six‐coordinated bismuth atoms, which are bound together via two bridging chlorine atoms. The two bismuth atoms Bi(1) and Bi(1a) and the two bridging chlorine atoms Cl(2) and Cl(2a) form the Bi 2 Cl 2 plane. The two tridentate ligand molecules coordinate via the same atoms as shown in complex 5. In addition, they form two parallel planes, which are perpendicular to the Bi 2 Cl 2 plane. With regard to the center of the Bi(1)‐Bi(2) axis they are central point symmetrical, i.e. one pyridine ring lies above and the other beneath the Bi 2 Cl 2 plane. Bismuth(III) chloride and pyridine‐2‐carboxaldehydethiosemicarbazone 1 b or 2‐acetylpyridine‐thiosemicarbazone 1 c form complexes of group G. Three chlorine atoms and a bidentate ligand are coordinated to the bismuth(III) central atom. The bidentate ligand bound to the centra