Tetrathiafulvalenium salts of planar PtII, PdII, and CuII 1,2-dithio-oxalato-S,S′ anions. Synthesis, chemistry and molecular structures of bis(tetrathiafulvalenium) bis(1,2-dithio-oxalato-S,S′)palladate(II), [ttf]2[Pd(S2C2O2)2], and of bis(tetrathiafulvalenium)tetrathiafulvalene bis(1,2-dithio-oxalato-S,S′)platinate(II), [ttf]3[Pt(S2C2O2)2]
Abstract
Tetrathiafulvalenium (ttf) salts with inorganic dithio-oxalato anions, [ttf]2[Pd(S2C2O2)2](1), [ttf]2[Pt(S2C2O2)2](2) and [ttf]1.0[Cu(S2C2O2)2](3) were prepared by reaction of [ttf]3[BF4]2 and the corresponding [A]2[M(S2C2O2)2](where A = NEt4 or AsPh4; M = PdII PtII or CuII) in acetonitrile, or by electrocrystallization of neutral ttf in acetonitrile containing [NEt4]2[Pt(S2C2O2)2] in the case of [ttf]3[Pt(S2C2O2)2](4). The crystal and molecular structures of compounds (1) and (4) were determined by single-crystal X-ray diffraction. Compound (1) crystallizes in the monoclinic space group P21/c with unit-cell dimensions a= 9.447(2), b= 11.044(4), c= 12.299(2)Å, β= 113.52(2)°, and Z= 2. The ttf molecules exist as dimeric (ttf˙+)2 and form mixed stacks with the anions along the b axis of the unit cell. Compound (4) crystallizes in the monoclinic space group P21/c with unit-cell dimensions a= 9.754(2), b= 13.905(3), c= 13.733(3)Å, β= 119.21 (1)°, and Z= 2. Two crystallographically independent ttf units are present: the first comprises dimerized (ttf˙+)2, and the Second is neutral (ttf0) and perpendicular to the dimer. The compound is better formulated as [(ttf˙+)2(ttf0)][Pt(S2C2O2)2]. Electron spin resonance, infrared and X-ray photoelectron spectroscopic studies of the palladium and platinum derivatives indicate that, in each compound, the metal ion is in the oxidation state +2 and that ttf is present as (ttf˙+)2and ttf0 as found in the crystal structure. The copper compound contains the metal ion in the uncommon oxidation state +3. Infrared, photoelectron, and electronic spectra suggest that the molecular structure of this compound consists of (ttf˙+)2dimers and planar diamagnetic [Cu(S2C2O2)2]–.
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