Metal-dependent assemblies of an unusual pentanuclear cadmium cluster and a fascinating 3D 4-connected lead-containing framework

Two new coordination compounds, [Cd5(L)2(OH)Cl3]·7H2O (1) and [Pb3(L)2]·3H2O (2) (H3L = 2,4,6-tris[1-(3-carboxy-2-oxidroxypyridinium)-ylmethyl]-mesitylene), have been synthesized under similar hydrothermal conditions. Their structures have been determined by single-crystal X-ray diffraction analyses and further characterized by elemental analyses, IR spectra, and thermogravimetric analyses. In 1, two L anions bridge five Cd(II) atoms in μ4-η1:η1:η1:η1:η1:η1 coordination modes to furnish an unusual pentanuclear Cd(II) cluster. In 2, each L anion links five Pb(II) atoms in a μ5-η0:η1:η1:η0:η2:η1:η0:η2:η1 coordination fashion to generate a fascinating 3D trinodal 4-connected net with point symbol of (62·84)(4·63·82)(42·62·82). The differences between 1 and 2 indicate that metal centers may have significant effects on their final structures. In addition, compound 1 shows an emission at 404 nm when it was excitated at 341 nm.

Graphical abstractThrough the variations of the central metals, an unusual pentanuclear Cd(II) cluster and a 3D 4-connected framework based on a flexible tricarboxylate have been synthesized under the similar hydrothermal conditions.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Compound 1 displays an unusual 0D pentanuclear Cd(II) cluster structure. ► Compound 2 exhibits a 3D 4-connected (62·84)(4·63·82)(42·62·82) topology. ► The central metals play significant roles in the formation of the final structures.