Spectroscopic and structural investigation on tetrahalomercurates(II). Crystal and molecular structures of bis(N-ethylmorpholinium)tetrachloromercurate(II) and (N-ammoniumethylmorpholinium)tetrachloromercurate(II) complexes

Abstract

Compounds of the type [LH] 2HgX 4 and [LH 2]HgX 4 [LH = N-ethylmorpholinium cation; LH 2 = N-ammoniumethylmorpholinium dication; X = Cl, Br, 1] were prepared and characterized by means of Raman and far-IR spectroscopies. For two compounds [LH] 2HgCl 4 ( A) and [LH 2]HgCl 4 ( B), the crystal structures were also determined. Crystals of both compounds show that they are composed of discrete monomeric [HgCl 4] 2− units and counter-ions, [LH +] and [LH 2 2+]. Coordination around the mercury atoms is distorted tetrahedral, arising from hydrogen bonding. In compound ( A) there is one long (2.559(5) Å) and three short (av. 2.456(15) Å) HgCl distances, while in compound ( B) a continuous range of HgCl distances (2.395(3)–2.562(3) Å) is present. The deviations from tetrahedral geometry of the [HgCl 4] 2− units do not play a significant role in vibrational spectra.