REACTIONS OF IRON HALIDES WITH THIOLS CONTAINING NITROGEN DONOR ATOMS- THE STRUCTURE OF AN IRON(III) COMPLEX OF 2,2'-DIMERCAPTODIPYRIDINE

By reaction of iron(II) and iron(III) with 2-mercaptopyridine (HMP) an d 2,5-dimercapto-1,3,4-thiadiazol (H(2)DMTD), the complexes FeCl2(HMP) (2), FeCl4(HDMP) (DMP = 2,2'-dimercaptodipyridine) and Fe(HDMTD)(2) ha ve been prepared and characterized by IR and Mossbauer spectroscopies. The crystal structure of FeCl4(HDMP) has been determined by an X-ray diffraction study. The compound is triclinic, space group P1, with a = 7.946(1), b = 14.067(2), c = 7.623(1) Angstrom, alpha = 97.0(1), beta = 92.7(1), gamma = 78.4(1)degrees, Z=2. The structure consists of dis crete [HDMP(+)] cations and [FeCl4-] anions; the cation is formed by t wo pyridine rings connected by an S-S bridge formed by oxidation of HM P without any short contact with the anion which forms a nearly perfec t tetrahedron.