Dinuclear silver(I) and copper(II) complexes of hexadentate macrocyclic ligands containing p-xylyl spacers

The cyclocondensation of terephthalic aldehyde with N, N-bis( 3-aminopropyl)methylamine in the presence of silver(I) gives the dinuclear tetraimine Schiff base macrocyclic complex, [Ag2L1](NO3)(2) (L-1 = 7,22-N,N'-dimethyl-3,7,11,18,22,26-hexaazatricyclo[26.2.2(1.18). 2(13.16)]-tetratricosa-2,11,13,15,17,26,28,30,31,33-decaene). [Ag2L1](NO3)(2) crystallizes in the monoclinic space group P2(1)/c, with a = 14.153(6), b = 12.263(4), c = 9.220(2) Angstrom, beta = 97.52(3) Angstrom and Z = 2. The silver ions are strongly coordinated at each end of the macrocycle by the two imine nitrogen atoms [2.177(3) and 2.182(3) Angstrom] with close interatomic interactions to an oxygen atom of a nitrate ion and an amine nitrogen atom [2.580(2) and 2.690(2) Angstrom]. The Ag ... Ag distance is 6.892(3) Angstrom. The free tetraimine macrocycle, L-1, was obtained by treatment of [Ag2L1](NO3)(2) with an excess of iodide, and the reduced hexaaza derivative 7,22-N,N'-dimethyl-3,7,11,18,22,26-hexaazatricyclo[26.2.2(1.18).2(13.16)]tetratricosa-13,15,28,30,31,33-decaene, L-2, was prepared by reduction of [Ag2L1](NO3)(2) with NaBH4. The copper(II) complexes of the reduced ligand, [Cu2Cl2L2]Cl-2 . CH3OH, [Cu2Cl2L2](PF6)(2) and [Cu-2(CH3CO2)(2)L-2](PF6)(2) . 4H(2)O, have been prepared and characterized.