CHEMISTRY OF ORGANOMETALLOID COMPLEXES WITH POTENTIAL ANTIDOTES - STRUCTURE OF AN ORGANOARSENIC(III) DITHIOLATE RING

The reactions of several arylarsenic dichlorides with the vicinal dithiols HSCH2CH(SH)CH2OH (British Anti-Lewisite, BAL) and meso-HOOCCH(SH)CH(SH)COOH (dimercaptosuccinic acid, DMSA) were investigated. They readily formed five-membered rings with the dithiolate groups chelated to the arsenic(III) center. The complexes were characterized by a variety of spectroscopic techniques, which indicate that the dithiolates chelate tightly to the arsenic(III) through the sulfur atoms. The complex between tolylarsenic dichloride and BAL was characterized by single-crystal X-ray diffraction. The cell is monoclinic, of space group P21/n, with a = 13.343 (2) Å, b = 5.116 (1) Å, c = 17.196 (3) Å, β = 96.66 (1)°, Z = 4, V= 1166.0 (6) Å3, R = 0.039, and Rw>= 0.048. The structure contains a five-membered arsenic(lll) dithiolate with pyramidal geometry around the arsenic atom. Though both syn and anti isomers are possible, only the anti isomer is isolated. The lone pairs on the oxygen atoms do not appear to be involved in bonding. © 1990, American Chemical Society. All rights reserved.