Synthesis, structure, and properties of Schiff base iodobismuthate and its alteration in DMSO solution

New hybrid iodobismuthates (C12H18N2)(BiI4)2 (1, C12H18N2 is N,N´-bis(1- methylethylidene)-1,4-benzоdiammonium dication) and (C6H4(NH3)2) [Bi2I8•2DMSO]•4DMSO (2, C6H4(NH3)2 is p-phenylenediammonium dication) were synthesized and their crystal structures were established. Compound 1 crystallizes in the space group P21/n, a = 7.632(4), b = 13.471(6), c = 14.556(5) A, β = 93.57(4)°; compound 2 crystallizes in the space group P $$\overline 1 $$ , a = 9.208(4), b = 12.203(5), c = 13.600(5) A, α = 110.20(3)°, β = 97.28(4)°, γ = 110.04(4)°. In the crystal structure of compound 1, one-dimensional infinite BiI 4 – polyanions are linked into a three-dimensional structure by N,N'-bis(1-methylethylidene)- 1,4-benzоdiammonium dications through N–H…I and C–H…I hydrogen bonds. Compound 1 is stable up to 200 °С, optical studies showed that it has a band gap of 2.15 eV. The recrystallization of compound 1 from DMSO is accompanied by the transformation of chain BiI 4 – anions to binuclear [Bi2I8•2DMSO]2– anions, while the azomethine cation decomposes to form a p-phenylenediammonium dication.