SYNTHETIC CONDUCTING MATERIALS .11. DINUCLEAR COPPER-CHELATES WITH 3,6-BIS(2-PYRIDYL)-4-CYANO-PYRIDAZINE LIGAND AS A DONOR TO TCNQ

Dinuclear copper chelates containing 3,6-bis(2-pyridyl)4-cyano-pyridazine(PCPA) ligand have been synthesized where copper is either in Cu(I) or Cu(II) state. Metatheses between the dinuclear copper chelates and LiTCNQ (or Et3NH(TCNQ)2) yielded black needle-like charge trasfer complexes in the form of Cu2(PCPA)2(TCNQ)I and Cu2(PCPA)2(TCNQ)2I2. These complexes have been characterized by elemental analysis, infrared and electronic spectroscopy. The degree of charge transfer was estimated by external C=C stretching, CN stretching, and CH bending frequency in these complexes. Magnetic susceptibility measurement and electron paramagnetic resonance spectroscopy were employed to investigate the physical properties of electrons in the solid state crystals. The EPR results show that Cu2(PCPA)2(TCNQ)I has g=2.004 value with peak-to-peak width Hpp=5 gauss and unchanged from 300 to 77K The Cu2(PCPA)2(TCNQ)2I2 has g=2.003 value and Hpp=14 gauss at 278K which broadened to 20 gauss at 77K. The variable temperature electric conductivity measurement show that the conductivities were 5.6x10(-5) and 2.7x10(-5) Scm-1 for Cu2(PCPA)2(TCNQ)I and Cu2(PCPA)2(TCNQ)2I2, respectively, at 300K, and the activation energies were 0.17 eV for the former and 0. 18 eV for the later.