Synthesis of Pyridine NS(2) Ligands Incorporating 1-Methoxycarbonyl-2-thio(o-carborane). Are They a Route to "Carboranethiophene" Compounds?
Facilitated benzothiophene condensation has been successfully achieved in pyridinedithia(S-phenyl)-substituted compounds, by complexation with Pd(II). In this work, the phenyl fragment in 2,6-bis(2'-methoxycarbonylphenylthiomethyl)pyridine is replaced by o-carborane. This moiety is often treated as a three-dimensional aromatic system, thus it was worthwhile to see their comparative behavior toward Pd(II). To perform the reaction the new compound 2,6-bis(2'-methoxycarbonyl-1',2'-carboranyl-1'-thiomethyl)pyridine has been synthesized. Its complexation behavior toward Pd(II), using an alcohol as a solvent, induces the cluster's partial degradation and the reduction of Pd(II) to Pd(0). The reaction of the partially degraded ligand, [2,6-bis(7'-methoxycarbonyl-7',8'-carboranyl-7'-thiomethyl) pyridine](2)(-) with Pd(II) leads to a dinuclear species, where the ligand acts in a bidentate mode. One of the ligand's arms in the complex is uncoordinated and free. This result is supported by ME (MALDI-TOFF) and (1)H NMR variable-temperature studies.
Teixidor
Francesc
F
Institut de Ciència de Materials, CSIC, Campus U.A.B., 08193 Bellaterra, Spain.
Anglès
Pilar
P
Viñas
Clara
C