Synthesis, structure and magnetic properties of a new one-dimensional copper(II) complex with [Cr(CN)6]3-.: Comparison with the [Fe(CN)6]3- analogue

A new complex of formula {[Cu(L)][Cu(L)Cr(CN)(6)]ClO4. 2H(2)O}(n) 1 (L is meso-5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane) has been prepared from the reaction of [Cr(CN)(6)](3-) and [Cu(L)](2+), and its structure and magnetic properties studied. The structure consists of a discrete [Cu(L)](2+) cation and an anionic fragment formed by [Cu(L)Cr(CN)(6)](-) in which the Cu-II is coordinated to four N atoms of the macrocycle and two CN groups of the hexacyanometalate in trans positions to give a one-dimensional compound. The compound shows a moderate ferromagnetic coupling. In order to describe its magnetic data a new formula was developed for the magnetic susceptibility of an isotropic ferromagnetic S = 1/2 and 3/2 Heisenberg chain assuming a variation of chi T-M vs. the length N. The best least-squares fit gives J = 4.82 cm(-1), g = 2.02 and R = 1.23 x 10(-4).