Coordination chemistry of bis(2-pyridylimine) ligands with Ag(I): formation of two structurally different coordination polymers and one metallocycle controlled by linker and the solvent system

Reaction of equimolar amounts of AgClO 4 and bis[4-(2-pyridylmethyleneamino)phenyl] methane (L 1 ) or bis[4-(2-pyridylmethyleneamino)phenyl] ether (L 2 ) in a 1:1 solvent mixture of CH 3 CN and CH 2 Cl 2 leads to the formation of two infinite coordination polymers of the composition {[Ag(L 1 )]ClO 4 ·CH 3 CN} n ( 1 ) and {[Ag(L 2 )]ClO 4 ·CH 2 Cl 2 } n ( 2 ). Whereas 1 represents a homochiral single-stranded helicate the related complex 2 shows a typical zigzag chain arrangement. Both structures are characterized by a distorted tetrahedral coordination environment of the Ag(I) centres each based on a N 4 coordination pattern of two ligand molecules. The resulting strands are connected by a hydrogen bonding network including ClO 4 − anions and solvent molecules forming 2-D layers. Additional π–π and CH–π interactions between the aromatic parts of the ligand molecules give a 3-D arrangement of the packing. In contrast, a discrete dinuclear metallocycle, [Ag 2 (L 2 ) 2 ](ClO 4 ) 2 ·CH 3 OH ( 3 ), has been formed by reaction of AgClO 4 with L 2 when CH 2 Cl 2 in the solvent mixture was replaced by CH 3 OH. Again each Ag(I) has a distorted tetrahedral geometry and is coordinated to two pyridylimine units of two ligand molecules. Additional weak hydrogen bonds involving perchlorate and solvent molecules as well as edge-to-face and face-to-face π–π interactions allow a 3-D packing arrangement.