Control of molecular architecture by the degree of deprotonation:: self-assembled di- and tetranuclear copper(II) complexes of N,N′-bis(2-pyridylmethyl)pyrazine-2,3-dicarboxamide

In the absence of added base, a deep navy-blue dimeric copper complex [Cu-II(H2L)(MeCN)](2)(BF4)(4) (1) of the nondeprotonated bis-terdentate diamide ligand H2L self-assembles whereas in the presence of base a grass-green [2 X 2] grid complex [Cu-II(HL)](4)(BF4)(4) (2) of the monodeprotonated ligand HL-, a rare example of a discrete grid of pyrazine-bridged metal ions, is formed.