The Crystal Structure of Zineb, Seventy-Five Years Later

Ethylene bis(dithiocarbamates) (EBDTCs) have been used as staple fungicides for over 75 years. The first industrially manufactured EBDTC was zineb, zinc ethylene bis(dithiocarbamate), marketed under the trade name Dithane. Even though zineb has been used as a fungicide since the 1940s, its crystal structure has remained unknown. Herein, we describe the crystal structure of zineb (triclinic crystal system, space group P (1) over bar, a = 7.5094(9) angstrom, b = 9.4356(9) angstrom, c = 7.4120(7) angstrom, alpha = 107.945(8)degrees, beta = 100.989(7)degrees, gamma = 105.365(8)degrees, V = 460.07(10) angstrom(3)). The inorganic fragment of the structure consists of two Zn2+ cations, coordinated by the thiocarbamate groups. There are four Zn-S bonds with lengths in the range of 2.325-2.426 angstrom, and one rather long Zn-S contact of 2.925(8) angstrom. Inorganic fragments are linked by organic EBDTC ligands to form extended, polymeric layers. The layers are packed in an ABAB manner, related by the inversion symmetry and held together by a hydrogen bonding network. In this article, in addition to describing the crystal structure, we correlate the structural features with the vibrational spectroscopic and thermal characteristics of zineb, and we provide a short summary of the major developments of fungicides in the 20th century.