Structural control: can [2 × 2] silver grids be formed from 4,5-disubstituted 3,6-di(2-pyridyl) pyridazines?CCDC 1023446-1023452. For crystallographic data in CIF or other electronic format see DOI: 10.1039/c4ce01851f

The reaction of ligands based on 3,6-di(2-pyridyl)pyridazine with symmetrical carbocyclic rings fused to the pyridazine ring; 7,10-di(2-pyridyl)-8,9-diazafluoranthene ( L 1 ), 1,4-di(2-pyridyl)-6,7,8,9-tetrahydro-5 H -cyclo-hepta[ d ]pyridazine ( L 2 ), 1,4-di(2-pyridyl)-5,6,7,8-tetrahydro-phthalazine ( L 3 ), 1,4-di(2-pyridyl)-6,7-dihydro-5 H -cyclo-penta[ d ]pyridazine ( L 4 ) with silver salts gave a series of complexes ( 1-7 ). Characterisation of these using single crystal X-ray structure determination clearly showed that the steric bulk of the carbocycle affects the degree to which pyridine groups remain co-planar with pyridizine, and hence their ability to chelate. The more hindered ligands L 1 -L 3 form a mixture of bischelating and tetrabridging, while the least hindered ( L 4 ) was able to chelate exclusively. In the case of L 4 , the nature of the anion and solvent were also able to affect the outcome of the reaction, with tetrafluoroborate giving the first example of a 4,5-substituted 3,6-di(2-pyridyl)pyridazine ring forming a [2 × 2]-grid. Synthesis of a range of silver complexes of 4,5-disubstituted 3,6-di(2-pyridyl)pyridazine ligands illustrates the delicate structural control possible by changes in ligand conformation.