One-dimensional assembling of diiodo[phthalocyaninato(l-)] chromate(III) molecules through neutral I-2 molecules. Alternating ferro-and antiferromagnetic interactions in the metal-radical system

摘要

Crystals of diiodo[phthalocyaninato(1-)] chromate(III) diiodine, CrPcl(2).l(2), were grown directly in the reaction of chromium powder with 1,2-dicyanobenzene under a stream of iodine at about 250 degreesC. The CrPcl(2).l(2) Complex crystallizes in the centrosymmetric space group of the triclinic system with one molecule per unit cell, with the cell dimensions a = 7.851(2) Angstrom, b = 8.402(2) Angstrom, c = 12.668(3) Angstrom, alpha = 80.32(3)degrees, beta = 74.06(3)degrees, gamma = 82.33(3)degrees, and V = 788.7(3) Angstrom(3). The X-ray single-crystal analysis shows that each of the centrosymmetric CrPcl(2) molecules is bridged by a neutral 12 molecule (detected also by Raman spectroscopy) and develops a polymeric one-dimensional structure. The magnetic measurements have been carried out in the temperature range 300-2 K. Temperature dependence of the effective magnetic moment, mu(eff), shows the ferro- and antiferromagnetic interactions in the system of the paramagnetic central Cr3+ ion and surrounding pi-conjugated radical ligand Pc(1-). The conductivity measurement on a polycrystalline sample exhibits weak temperature dependence (dsigma/dT < 0). The UV-vis spectrum exhibits, besides the B- and Q-bands, one additional band assigned to the electronic transition from a deeper level to the half-occupied HOMO level in the one-electron oxidized phthalocyaninato(1-) radical ligand. [References: 74]