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

Two isomorphic organically templated zinc/cobalt oxalates, (dmdabco)[Zn2(C2O4)3]·4H2O (1), and (dmdabco)[Co2(C2O4)3]·4H2O (2) (C2O42− = 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 dmdabco2+ templating agent was derived from simple in situ N-alkylation between methanol and 1,4-diazabicyclo[2,2,2]octane (dabco). Distinct from conventional Eschweiler-Clarke methylation containing excess formic acid and formaldehyde, such one-step methylation from methanol molecules is convenient. Both 1 and 2 exhibit a uninodal 3-connected 3-D interrupted open-framework, in which oxalate ligands have in-plane and out-of-plane connection modes.