Interaction of diiodine with Et4todit = 4,5,6,7-tetrathiocino [1,2-b:3,4-b′]diimidazolyl-1,3,8,10-tetraethyl-2,9-dithione. Crystal and molecular structure of Et4todit•2I2

Abstract

Spectrophotometric studies on the reaction between diiodine and the title ligand in ratios ranging from 1:1 to 1:20 in CHCl3 have shown the formation of a 1:1 charge-transfer complex. A general computer program has been used to refine the equilibrium constant and the extinction coefficients simultaneously. In the solid state a 1:2 (donor to acceptor) complex has been isolated and an X-ray structure analysis of the compound indicated that the crystals are monoclinic, space group C2/c with a = 16.317(4), b = 13.912(3), c = 12.879(3) Å, β = 111.24(2)°, Z = 4.The molecular structure shows that two sulphur-thioamide atoms of the ligand act as donor with respect to two diiodine molecules. The structural data of the organic molecule of the complex and those of the free molecule are very similar. Keywords: diiodine, thioamides, charge-transfer, structure, equilibrium-constants.