Synthesis and characterization of tetrathiafulvalene (TTF) and 7,7,8,8-tetracyanoquinodimethane (TCNQ) compounds with PdX2 (X = Cl, NO3 and hexafluoroacetylacetonate)

Tetrathiafulvalene (TTF) reacts with PdCl2, Pd(NO3)(2), and Pd(hfacac)(2) (hfacac = hexafluoroacetylacetonate) in ethanol to give (TTF)(1.5)PdCl2 (1a), (TTF)(3)Pd(NO3)(2) (1b) and (TTF)(4)Pd(hfacac)(2) (1c), respectively. PdCl(TCNQ)(2.5).CH3OH (2a) was obtained from the reaction of PdCl2 with LiTCNQ in Methanol via the partial replacement of Cl- in PdCl2 by TCNQ(-) anion, whereas the total substitution of the labile NO3 in Pd(NO3)(2) yielded Pd(TCNQ).CH3OH (2b). Pd(hfacac)(2)(TCNQ)(2).3CH(3)OH (2c) was obtained from Pd(hfacac)(2) and LiTCNQ in methanol. The prepared compounds were characterized by spectroscopic (IR, UV, XPS) methods and magnetic (EPR, magnetic susceptibility) studies. The powdered electrical conductivities (sigma(n)) of the prepared compounds at room temperature were about similar to10(-7) S.cm(-1). The effective magnetic moments were less than the spin-only value of one unpaired electron and no EPR signals from Pd metal ions were observed in any of the compounds, indicating that the Pd ions were diamagnetic and the magnetic moments arose from (TTF)(n) or (TCNQ)(n) moieties. The experimental evidences revealed that the charge transfer had occurred from (TTF)(n) moiety to the central Pd metal ion in 1a, 1b and 1c. Thus the TTF donors were partially oxidized, and the Pd metal ions were reduced from Pd(II) to Pd(0) oxidation state. The Pd metal ions in 2a and 2b were diamagnetic Pd(II) oxidation state, In contrast, the Pd metal ion was oxidized to Pd([V) state in 2c as a result of an addition of TCNQ(-) anion to Pd(hfacac)(2) in methanol. The oxidation states of the Pd metal ions were confirmed using the x-ray photoelectron spectroscopy.