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] M-4(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 stan nylations and Stille-type coupling reactions. The complexes were obtained b y self-assembly of the ligand with the metal salt. The single-crystal X-ray structure was determined for the Co complex 7 containing aminopyrimidine a s the hydrogen-bonding moiety [P (1) over bar; a = 15.4976(4), b = 18.2114( 6), c = 31.9538(10) Angstrom, a = 86.9809(13) beta = 83.4137(18), gamma = 6 7.2828(16)degrees]. The crystal structure reveals hydrogen bonding in one d irection, thus forming infinite chains of grids, whereas in the second dire ction of a layer, only weak attractive interactions are found. Anions and s olvent molecules are situated between the layers, thus inhibiting any direc t interaction between them. Cocrystallisation of the complementary complexe s should enable the recognition-controlled alternating arrangement of grids incorporating different metal ions in a chessboard-like manner.