MAGNETIC AND OPTICAL CHARACTERIZATION OF ONE-DIMENSIONAL ISOSTRUCTURAL SIGMA-BONDED TETRACYANOQUINODIMETHANIDO COMPLEXES OF NICKEL(II) AND COPPER(II)

The complex [CuL(tcnq)(2)] [L = droxyethyl-1,3,5,8,10,12-hexaazacyclot etradecane); tcnq = 7,7,8,8-tetracyanoquinodimethane] has been prepare d and crystallographically characterized. Its structure consists of li near chains of alternating copper-macrocycle and tetracyanoquinodimeth anide dimers sigma bonded to the copper atoms through a nitrile group. The compound is an insulator. The magnetic properties of both the cop per and corresponding nickel compounds are the sums of the contributio ns arising from the transition-metal ion in octahedral symmetry and of (tcnq)(2)(2-) dimers. The magnetic data were fitted by a model which accounts for contributions from independent Curie spins for the cation and a thermally activated triplet state for the dimerized anions. No magnetic interactions between the metal ion and tcnq's have been obser ved, even at low temperatures.