Two-level self-organisation of arrays of [2x2] grid-type tetranuclear metal complexes by hydrogen bonding

Here we report on the synthesis and characterisation of four new complexes of the [2x2] M₄^II grid-type (M = Co, Fe, Zn) with oligopyridine-derived ligands. The presence of aminopyrazine and aminopyrimidine moieties at the edge of the ligands potentially enables the formation of infinite hydrogen-bonded multi-grid networks. The ligands were synthesised by subsequent stannylations and Stille-type coupling reactions. The complexes were obtained by self-assembly of the ligand with the metal salt. The single-crystal X-ray structure was determined for the Co complex 7 containing aminopyrimidine as the hydrogen-bonding moiety [P1^-; a = 15.4976(4), b = 18.2114(6), c = 31.9538(10) Å, α = 86.9809(13), β = 83.4137(18), γ = 67.2828(16)°]. The crystal structure reveals hydrogen bonding in one direction, thus forming infinite chains of grids, whereas in the second direction of a layer, only weak attractive interactions are found. Anions and solvent molecules are situated between the layers, thus inhibiting any direct interaction between them. Cocrystallisation of the complementary complexes should enable the recognition-controlled alternating arrangement of grids incorporating different metal ions in a chessboard-like manner. © Wiley-VCH Verlag GmbH, 2001.