262273-35-8Relevant academic research and scientific papers
Chromium-(II) and -(III) over a planar oxo surface modelled by calix[4]arene anions: Redox chemistry and formation of Cr-C functionalities
Hesschenbrouck, Joelle,Solari, Euro,Floriani, Carlo,Re, Nazzareno,Rizzoli, Corrado,Chiesi-Villa, Angiola
, p. 191 - 198 (2000)
The metallation of [p-Butcalix[4](ONa)2(OMe)2] 1 was performed using [CrCl3(THF)3] and the resulting complex [Cr{p-Butcalix[4](O)2(OMe)2}(Cl)(THF)] 2 allowed entry into low valent and organometallic chemistry of chromium. In the presence of strong bases or nucleophiles the ligand underwent demethylation exemplified by the reaction of 2 with pyridine, which led to [C5H4NMe][Cr{p-Butcalix[4](O) 3(OMe)}Cr(py)(Cl)] 3. The alkylation of 2 was successful only when the concurrent reduction to CrII was irrelevant, in which case the two well characterized organometallic derivatives [Cr{p-Butcalix[4](O)2(OMe)2}(Mes)] 4 [Mes = 2,4,6-Me3C6H2] and [Cr{p-Butcalix[4](O)2(OMe)2}(η 5-C5H5)] 5 were obtained. None of them showed, even under photochemical or thermal forced conditions, any sign of reactivity, due to the kinetic inertness of the d3 configuration. Complex 2 was easily reduced to the chromium(II) derivative [Cr{p-Butcalix[4](O)2(OMe)2}(THF)] 6, which underwent facile oxidative functionalization. The reaction with O2 led to an unprecedented di-μ-oxo chromium(IV) derivative, [Cr2{p-Butcalix[4](O)2(OMe)2} 2(μ-O2)] 7, which displays a ferromagnetic coupling between the two d2 centres. The proposed structures are supported by X-ray analyses of complexes 2-4, 6 and 7. The Royal Society of Chemistry 2000.
