Dinuclear silver(I) complexes of bibracchial tetraimine Schiff base macrocycles derived from pyrrole-2,5-dicarbaldehyde

The cyclocondensation of pyrrole-2,5-dicarbaldehyde and the amines N,N-bis(2-aminoethyl)- and N,N-bis(3-aminopropyl)-2-(aminomethyl)pyridine in the presence of silver(I) nitrate yielded homodinuclear bibracchial tetraimine Schiff base macrocyclic complexes [Ag-2(L-3)] 1 and [Ag-2(H2L4)(ClO4)(2)]. CH3CN 2. In 1 the Ag ... Ag separation is 2.748 Angstrom. In 2 the silver atoms Ag(1) and Ag(2) are disordered over two sites with refined occupancies of 94.12 and 97.22% respectively. They are three-co-ordinate in the molecule having higher silver site occupancy and four-co-ordinate in that molecule having lower occupancy; the Ag ... Ag separations are 5.881 and 7.224 Angstrom respectively. There are protonated imine nitrogen atoms present in both molecules and the structure contains a disordered acetonitrile of crystallisation.