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 [CuII(H2L)(MeCN)]2(BF4)4(1) of the non-deprotonated bis-terdentate diamide ligand H2L self-assembles whereas in the presence of base a grass-green [2 × 2] grid complex [CuII(HL)]4(BF4)4(2) of the monodeprotonated ligand HL–, a rare example of a discrete grid of pyrazine-bridged metal ions, is formed.