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 tetramine Schiff base macrocyclic complex, [Ag2L1](NO3)2 (L1=7,22-N,N'-dimethyl-3,7,11,18, 22,26-hexaazatricyclo[26.2.21.18.213.16]-tetratricosa-2,11,13,15,1 7,26,28,30,31,33-decaene). [Ag2L1](NO3)2 crystallizes in the monoclinic space group P21/c, with a=14.153(6), b=12.263(4), c=9.220(2) Å, beta=97.52(3) Å 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) Å] with close interatomic interactions to an oxygen atom of a nitrate ion and an amine nitrogen atom [2.580(2) and 2.690(2) Å]. The Ag...Ag distance is 6.892(3) Å. The free tetraimine macrocycle, L1, was obtained by treatment of [Ag2L1](NO3)2 with an excess of iodide, and the reduced derivative 7,22-N,N'-dimethyl-3,7,11,18,22,26-hexaazatricyclo[26.2.21.18.213. 16]tetratricosa-13,15,28,30,31,33-decane, L2, was prepared by reduction of Ag2L1](NO3)2 with NaBH4. The copper(II) complexes of the reduced ligand, [Cu2Cl2L2]Cl2xCH3OH, [CU2Cl2L2](PF6)2 and [Cu2(CH3CO2)2L2](PF6)2x4H2O, have been prepared and characterized.