Synthesis and structure of bismuth complexes [Ph3(n-Pr)P] 2 + [Bi2I8 · 2Me2S=O]2−, [Ph3(iso-Bu)P] 2 + [Bi2I8 · 2Me2S=O]2−, [Ph3(n-Bu)P] 2 + [Bi2I8 · 2Me2S=O] 2−, and [Ph3(n-Am)P] 2 + [Bi2I8 · 2Me2S=O]2−

The complexes [Ph3(n-Pr)P]2+[Bi2I8 · 2Me2S=O]2− (I), [Ph3(iso-Bu)P]2+[Bi2I8 · 2Me2S=O]2− (II), [Ph3(n-Bu)P]2+[Bi2I8 · 2Me2S=O]2− (III), and [Ph3(n-Am)P]2+[Bi2I8 · 2Me2S=O] 2− (IV) are synthesized by reactions of triphenylalkylphosphonium iodide with bismuth iodide in dimethyl sulfoxide. In all complexes, the P atoms in cations have a distorted tetrahedral coordination (the CPC angles vary from 106.4(8)° to 114.8(2)°). In the dihedral centrosymmetric anions, the octahedral bismuth atoms are bound to each other by two bridging (br) iodine atoms (Bi-Ibr 3.167(1), 3.273(1) A (I); 3.1557(2), 3.2589(2) A (II); 3.1961(3), 3.3108(3) A (III); 3.1913(4), 3.3161(4) A (IV)), which are coplanar to four terminal (t) iodine atoms (Bi-It 2.956(1), 2.989(1) A (I); 2.9557(2), 2.9872(2) A (II); 2.9206(3), 2.9706(3) A ( III ); 2.9328(4), 2.9890(4) A (IV)). Two remaining positions at the bismuth atoms are occupied by the iodine atom (Bi-I 2.987(1) A (I); 3.0051(2) A (II); 2.8984(3) A (III); 2.9046(4) A (IV)) and the dimethyl sulfoxide molecule (Bi-O 2.458(12) A (I); 2.430(2) A (II); 2.507(3) A (III); 2.544(4) A (IV)).