Synthesis and X-ray characterisation of some heterometallic Hg–M complexes with 2-oxazolidone

Abstract

Mercury(II) acetate reacts with 2-oxazolidone (1,3-oxazolidin-2-one, C₃H₅NO₂) in methanol to produce [HgL₂](L = C₃H₄NO₂, the anion of 2-oxazolidone). An X-ray diffraction study has shown that the Hg atom binds to the ring nitrogen atom with a near linear N–Hg–N geometry. There are two HgL₂ groups in the asymmetric unit which are orthogonal to one another and linked via pairs of Hg ⋯ O interactions to form dimers. These bind to neighbouring units via weaker Hg–O interactions to form a one-dimensional chain polymer. When yttrium or lanthanide(III) nitrates are added to the reaction an isostructural series of compounds of formula [{Hg₂L₄M(NO₃)₃}_n], where MLa–Yb or Y, is obtained. A representative member of this group, [{Hg₂L₄Gd(NO₃)₃}_n], was studied by single-crystal X-ray diffraction methods. This forms a two-dimensional polymeric array comprising two sizes of metallamacrocyclic rings (16- and 48-membered) fused together, with the gadolinium(III) ion surrounded by nine oxygen atoms in a trigonal tricapped-prismatic arrangement. The IR, UV/VIS reflectance, EPR and solid-state NMR spectroscopic properties of these complexes and, where appropriate, those of [Hg₃L₆Co(NO₃)₂] and [Hg₂L₄Zn(NO₃)_1.33(OMe)_0.67] are reported.