Mixed-valence, disordered structures and characterization of iodine-doped phthalocyanines:: [YbPc2]I2 and [(AsPc)(Pc)]I2

Crystals of C64H32N16YbI2 and C64K32N16AsI2 were grown directly in the reaction of ytterbium or arsenic powder with 1,2-dicyandbenzene under a stream of iodine at 200 degrees C. Both partially oxidized phthalocyanine complexes crystallize in the P4/mcc space group of the tetragonal system with one molecule per unit cell, with the cell dimensions a 13.927(2) Angstrom, c = 6.409(1) Angstrom, and a = 13.926(2) Angstrom, c = 6.433(1) Angstrom for the Yb and As complexes, respectively. The space group of P4/mcc requires that both heavy (iodine and metal) atoms are disordered in these structures. The structures show columnar pseudo-monodimensional stacks of [YbPc2] or [(AsPc)(Pc)] units with an average nonintegral charge of +2/3 and linear chains of triiodide I-3(-) ions, which were detected by Raman spectroscopy. The monodimensional chains of I-3(-) ions and pseudo-monodimensional aggregates of [YbPc2](2/3+) or [(Aspc)(Pc)](2/3+),aligned along the c-axis of the crystals. The Yb3+ ion Lies in the center, whereas in the [(AsPc)(Pc)] unit the As3+ ion does not Lie in the center between the Pc rings. In the crystal of [(AsPc)(Pc)]I-2 both components in the [(AsPc)(Pc)](2/3+) unit (e.g., AsPc and Pc) with opposite charge are electrostatically interacting. The magnetic susceptibility measurement of the [YbPc2]I-2 shows typical Curie-Weiss behavior, and the effective magnetic moment is about 4.60 mu(B). The EPR measurement shows no signal for the Yb complex, while for [(AsPc)(Pc)]I-2 two signals are observed: a sharp narrow line at g = 2.0028 of width approximate to 2 G and a broad line at g = 2.0036 of width approximate to 9 G. The two EPR signals are associated with two different radical components: a phthalocyaninato (Pc-.) ring and [AsPc-.], respectively. Both free radicals are in resonance: [(As3+Pc2-)(Pc-.)] <-> [(As3+Pc-.)(Pc2-)]. Oxygen effects on the EPR signal of the [(AsPc)(Pc)]I-2 crystal have been detected. The conductivity measured on polycrystalline samples at room temperature equals 2.5-4 x 10(-2) and 2.2-3.5 x 10(-4) Omega(-1) cm(-1) for [YbPc2]I-2 and [AsPc(Pc)]I-2, respectively. Both complexes exhibit nonmetallic character in conductivity (d sigma/dT > 0).