Complexes with macrocyclic ligands. II. The crystal structures of HgCl2•18-crown-6 and CdCl2•18-crown-6, and the FAB mass spectrum of HgCl2•18-crown-6

Abstract

HgCl2 and CdCl2 form 1:1 complexes with 1,4,7,10,13,16-hexaoxacyclooctadecane (18-crown-6). The complexes are isostructural. The metal coordination is hexagonal bipyramidal, with chlorine atoms strongly coordinated in the axial positions and the 18-crown-6 in the equatorial place. The symmetry of the complex is crystallographically required to be [Formula: see text], but is very nearly [Formula: see text]. The Hg—Cl, Hg—O, Cd—Cl, and Cd—O distances are 2.314(1), 2.825(4), 2.3645(5), and 2.752(1) Å, respectively. Crystals of HgCl2•18-crown-6 are rhombohedral, space group [Formula: see text], a = 7.746(2) Å, α = 95.26(3)°, Z = 1 unit of HgCl2C12H24O6, R = 0.026 for 543 independent reflections with θ < 25°, I > 3σ(I). Crystals of CdCl2•18-crown-6 are also rhombohedral, space group [Formula: see text], a = 7.712(3) Å, α = 95.57(2)°, Z = 1 unit of CdCl2C12H24O6, R = 0.022 for 534 independent reflections with θ < 25°, I > 3σ(I).