Supramolecular architecture in nickel(II) polyamine tetracyanoquinodimethanido systems

Three different supramolecular architectures corresponding to [Ni(dien)(2)](TCNQ)(2) (dien = 1,4,7-triazaheptane; TCNQ = 7,7,8,8-tetracyanoquinodimethane), [Ni(trien)(TCNQ)(2)] (trien = 1,4,7,10-tetraazadecane), and[Ni(cyclam)(TCNQ)(2)] (cyclam = 1,4,8,11-tetraazacyclotetradecane) have been prepared and crystallographically characterized: [Ni(dien)(2)](TCNQ)(2), triclinic, <P(1)over bar>, a = 8.319(2) Angstrom, b = 9.074(2) Angstrom, c = 11.145(3) Angstrom, alpha = 80.91(2)degrees, beta = 74.10(2)degrees, gamma = 82.12(2)degrees, Z = 1; [Ni(trien)(TCNQ)(2)], orthorombic, Pccn, a = 22.677(7) Angstrom, b = 7.888(5) Angstrom, c = 15.801(3) Angstrom, Z = 4; [Ni(cyclam)(TCNQ)(2)], triclinic, <P(1)over bar>, a = 8.699(2) Angstrom, b = 9.752(3) Angstrom, c = 10.138(2) Angstrom, alpha = 87.29(2)degrees, beta = 77.14(2)degrees, gamma = 75.00(2)degrees, Z = 1. All of them are built by dimeric units (TCNQ)(2)(2-) which are out of the coordination sphere in [Ni(dien)(2)](TCNQ)(2) and a-coordinated to the metal in cis and trans positions in [Ni(trien)(TCNQ)(2)] and [Ni(cyclam)(TCNQ)(2)], respectively. In the two latter compounds the bonded dimeric units (TCNQ)(2)(2-), formed by intermolecular interactions, give rise to infinite chains consisting of alternating [Ni(N-4)](2+) and (TCNQ)(2)(2-) moieties in the crystal. The existence of hydrogen bonds between the TCNQ nitriles and amine groups belonging to the metal fragments stabilizes the supramolecular architecture, increasing the dimensionality of the interactions. The spectroscopic and magnetic properties are discussed according to the structural models.