COMPLEXES OF HGCL2 AND HGBR2 WITH NITRILOTRIACETAMIDE

The two complexes 2kappa2O';2kappaO,1:2kappa2O'-bis(dichloromercury) [ Hg-Cl2(C6H12N4O3)]2, and 2kappa2O';2kappaO,1:2kappa2O'-bis(dibromomerc ury), [Hg-Br2(C6H12N4O3)]2, are isostructural, and represent the third case of metal complexes with nitrilotriacetamide [NTAM = N(CH2CONH2)3 ]. [Pb and Co complexes have been reported by Sucheck, Finnen, Pinkert on, Skrzypczak-Jankun, Vijayakumar & Smith (1991). Am. Crystallogr. As soc. Meet., Toledo, Abstract PJ17.] The (NTAM:HgX2)2 complexes are cen trosymmetric oxygen-bridged dimers. Each metal ion binds to six donors (2X, 1N, 3O; X = Br, Cl) at distances of 2.3-2.9 angstrom, although r etaining the hexagonal bipyramidal configuration observed in complexes where Hg(II) is eight-coordinate. Two 'empty sites' are occupied by d onors from other molecules (X and N atoms) at distances of 3.7-4.1 ang strom. Two out of three amine groups of NTAM participate in hydrogen b onds, while the third is utilized as a ligand in the 'empty site' of t he coordination sphere of the neighboring Hg(II).