EFFECT OF THE NH---S HYDROGEN-BOND ON THE NATURE OF HG-S BONDING IN BIS[2-(ACYLAMINO)BENZENETHIOLATO]MERCURY(II) AND BIS[2,6-BIS(ACYLAMINO)BENZENETHIOLATO]MERCURY(II) COMPLEXES

2-(Acylamino)benzenethiolate complexes of Hg(II) having an intramolecu lar NH-S hydrogen bond, Hg[2-(pivaloylamino)benzenethiolato](2) and Hg [2,6-bis(pivaloylamino)benzenethiolato](2), were synthesized and the c rystal structures were determined. The crystal structure of Hg[2-(piva loylamino)benzenethiolato](2) . 1/2H(2)O shows the presence of two dis tinct conformers with different C-S-(Hg)-S-C torsion angles (81.7 and 176.6 degrees). The crystal structure of Hg[2,6-bis(pivaloylamino)benz enethiolato](2) indicates the presence of ordinary Hg-S bonds (2.335(2 ) and 2.342(2) Angstrom) and a straight linear coordination (S-Hg-S = 174.7(1)degrees) with a weak interaction of one of the amide CO groups toward HE(II). A weak NH-S hydrogen bond in both complexes is detecte d from the IR spectra in the solid state. The Hg-199 NMR spectra show the high-field shift with a decrease in the S --> Hg(II) ligand-to-met al charge transfer by the NH-S hydrogen bonding. The high-field shift by the double NH-S hydrogen bond is far greater than that by the p-sub stituent effect of the electron-withdrawing group (OMe, H, NHCOCH3, Cl , NO2) on the benzenethiolate ring.