One-Dimensional Assembling of Diiodo[phthalocyaninato(1−)] Chromate(III) Molecules through Neutral I₂ Molecules. Alternating Ferro- and Antiferromagnetic Interactions in the Metal−Radical System

Crystals of diiodo[phthalocyaninato(1−)] chromate(III) diiodine, CrPcI2·I2, were grown directly in the reaction of chromium powder with 1,2-dicyanobenzene under a stream of iodine at about 250 °C. The CrPcI2·I2 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) Å, b = 8.402(2) Å, c = 12.668(3) Å, α = 80.32(3)o, β = 74.06(3)o, γ = 82.33(3)o, and V = 788.7(3) Å3. The X-ray single-crystal analysis shows that each of the centrosymmetric CrPcI2 molecules is bridged by a neutral I2 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, μeff, shows the ferro- and antiferromagnetic interactions in the system of the paramagnetic central Cr3+ ion and surrounding π-conjugated radical ligand Pc(1−). The conductivity measurement on a polycrystalline sample exhibits weak temperature dependence (dσ/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.