RESUMO
A film of [Pd(R2pipdt)(dmit)] (1), where R2pipdt = 1,4-didodecyl-piperazine-2,3-dithione (acceptor) and dmit = 2-thioxo-1,3-dithiole-4,5-dithiolate (donor) incorporated into a polymethylmethacrylate (PMMA) matrix, showing a good second-harmonic generation, has been prepared for the first time in the class of dithione-dithiolate 2nd order NLO-chromophores. Moreover full characterization of 1, including molecular second-order NLO properties in solution, is reported.
RESUMO
We report the synthesis, structure, and physical properties of (BEDT-TTF)[Ni(tdas)2] [BEDT-TTF, or ET, is bis(ethylenedithio)tetrathiafulvalene; tdas is 1,2,5-thiadiazole-3,4-dithiolate], which is the first example of a salt containing monomeric [Ni(tdas)2]- monoanions. This salt, which crystallizes in the monoclinic space group P2(1)/c with a = 17.2324(6) A, b = 13.2740(5) A, c = 10.9467(4) A, beta = 96.974(2) degrees, and V = 2485.5(2) A(3), forms a layered structure. One layer contains dimerized BEDT-TTF electron donor molecules and isolated [Ni(tdas)2]- monoanions, while the second layer contains chains of [Ni(tdas)2]- monoanions. Conductivity measurements show that (BEDT-TTF)[Ni(tdas)2] has a semiconductor-to-semiconductor transition near 200 K, while magnetic measurements indicate that it is an S = 1/2 paramagnet with weak antiferromagnetic coupling. Reflectance spectra reveal bands in the near-infrared region (6.6 x 10(3) and 10.6 x 10(3) cm(-1)) which are typical of (BEDT-TTF)2(2+) dimers. From these data, we can conclude that the unpaired electron lies on the [Ni(tdas)2]- anions. Tight-binding band structure calculations were used to analyze the electronic structure of this salt.
RESUMO
A simple method to obtain in high yields mixed-ligand nickel-dithiolene complexes, which show strong negative solvatochromism and negative first molecular hyperpolarizability, and the use of Raman spectroscopy to establish the extent of electronic delocalisation in these complexes, are reported.
