Template-directed syntheses of two 3D metal oxalates: <i>in situ</i> N-methylation and crystal structures

<p>Two isomorphic organically templated zinc/cobalt oxalates, (dmdabco)[Zn<sub>2</sub>(C<sub>2</sub>O<sub>4</sub>)<sub>3</sub>]·4H<sub>2</sub>O (<b>1</b>), and (dmdabco)[Co<sub>2</sub>(C<sub>2</sub>O<sub>4</sub>)<sub>3</sub>]·4H<sub>2</sub>O (<b>2</b>) (C<sub>2</sub>O<sub>4</sub><sup>2−</sup> = oxalate; dmdabco = N,N′-dimethyl-1,4-diazabicyclo[2,2,2]octane), have been prepared under solvothermal conditions and characterized by X-ray structural analyses. The dmdabco<sup>2+</sup> templating agent was derived from simple <i>in situ</i> N-alkylation between methanol and 1,4-diazabicyclo[2,2,2]octane (dabco). Distinct from conventional <i>Eschweiler</i>-<i>Clarke</i> methylation containing excess formic acid and formaldehyde, such one-step methylation from methanol molecules is convenient. Both <b>1</b> and <b>2</b> exhibit a uninodal 3-connected 3-D interrupted open-framework, in which oxalate ligands have <i>in</i>-<i>plane</i> and <i>out</i>-<i>of</i>-<i>plane</i> connection modes.</p>