Estudio de las interacciones débiles presentes en sólido y en disolución en complejos de paladio y platino

Abstract

In the present work it is studied the synthesis, structural characterization and reactivity of mono- bi- and tetranuclear complexes of Palladium (II) and Platinum (II). We present the mononuclear complexes with the ortomethalated hydrazone, formulated: [Pd{C6H4-N(R)-N=C(CH3)-C5H4N}(?1-L)]n , where: R = H, CH3; L = Cl, 2,6-dimethylpiridine, PMe2Ph, PMePh2, dppm, (Ar-NNN-Ar)-, Ar = 4-(CH3O)C6H4, 4-(CH3)C6H4, C6H5, 4-F-C6H4, C6F5 and the binuclear complexes: [Pd2{C6H4-N(R)-N=C(CH3)-C5H4N}({C6H4-N(R¿)-N=C(CH3)-C5H4N}(µ-LL)]n (where: R y R¿ = H, CH3 R = R¿ (binuclear complex with two equivalent half) or R ? R¿ (binuclear complex with two non-equivalent half), LL = dppm, dppe y (Ar-NNN-Ar)-, Ar = 4-(CH3)C6H4, 4-F-C6H4, C6F5), let us establish correlations about the weak interactions in solution. Also, we have deprotonated the N-H group of the methalated hydrazone ligand of the prepared complexes to obtain zwitterionic species, with very rare colours to Palladium(II) complexes: dark green, blue and violet. This new species were characterized in solution by the NMR spectroscopy. On the other hand, we have synthesized the (?,S,S) and (?,S,S) diastereoisomers of the complex [{Pd(C6H4-N=N-Ph)}2{µ-(S)-(OC{CH(CH3)Br}N-Tol)}2], achieving the co-crystallization of both isomers together. We have also obtain monocrystals to been studied by RX monocrystal diffraction of the Cope-Siekman complex [{Pd(C6H4-N=N-C6H5)}2(µ-Cl)2], first described in 1965. Finally, we have synthesized tetranuclear complexes [Pd4(µ-LL)4(µ-X)4], where LL = 4-F-C6H4-NNN-C6H4-F-4, Tol-NC(CH3)N-Tol and X = Cl, Br, I). The structures are very different for these isoelectronic ligands with the central skeleton NNN y NC(R)N. The ligands hydrazone and azobencene ortomethalated to Palladium(II) form extensive p systems able to give p-p interactions. These interactions, together with other interactions as the hydrogen bonds, had been studied in the solid state, by RX diffraction, and in solution, by 1H NMR spectroscopy.