The metallation of [p-Bu(t)calix[4](ONa)(2)(OMe)(2)] 1 was performed using [CrCl3(THF)(3)] and the resulting complex [Cr{p-Bu(t)calix[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-Bu(t)calix[4](O)(3)(OMe)}Cr(py)(Cl)] 3. The alkylation of 2 was successful only when the concurrent reduction to Cr-II was irrelevant, in which case the two well characterized organometallic derivatives [Cr{p-Bu(t)calix[4](O)(2)(OMe)(2)}(Mes)] 4 [Mes=2,4,6-Me3C6H2] and [Cr{p-Bu(t)calix[4](O)(2)(OMe)(2)}(eta(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 d(3) configuration. Complex 2 was easily reduced to the chromium(II) derivative [Cr{p-Bu(t)calix[4](O)(2)(OMe)(2)}(THF)] 6, which underwent facile oxidative functionalization. The reaction with O-2 led to an unprecedented di-mu-oxo chromium(IV) derivative, [Cr-2{p-Bu(t)calix[4](O)(2)(OMe)(2)}(2)(mu-O-2)] 7, which displays a ferromagnetic coupling between the two d(2) centres. The proposed structures are supported by X-ray analyses of complexes 2-4, 6 and 7.

Chromium-(II) and Chromium-(III) over a Planar Oxo Surface Modelled by Calix[4]arene Anions: Redox Chemistry and Formation of Cr-C Functionalities / J., Hesschenbrouck; E., Solari; C., Floriani; N., Re; Rizzoli, Corrado; A., CHIESI VILLA. - In: DALTON. - ISSN 1470-479X. - ?:(2000), pp. 191-198. [10.1039/a908499a]

Chromium-(II) and Chromium-(III) over a Planar Oxo Surface Modelled by Calix[4]arene Anions: Redox Chemistry and Formation of Cr-C Functionalities

RIZZOLI, Corrado;
2000-01-01

Abstract

The metallation of [p-Bu(t)calix[4](ONa)(2)(OMe)(2)] 1 was performed using [CrCl3(THF)(3)] and the resulting complex [Cr{p-Bu(t)calix[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-Bu(t)calix[4](O)(3)(OMe)}Cr(py)(Cl)] 3. The alkylation of 2 was successful only when the concurrent reduction to Cr-II was irrelevant, in which case the two well characterized organometallic derivatives [Cr{p-Bu(t)calix[4](O)(2)(OMe)(2)}(Mes)] 4 [Mes=2,4,6-Me3C6H2] and [Cr{p-Bu(t)calix[4](O)(2)(OMe)(2)}(eta(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 d(3) configuration. Complex 2 was easily reduced to the chromium(II) derivative [Cr{p-Bu(t)calix[4](O)(2)(OMe)(2)}(THF)] 6, which underwent facile oxidative functionalization. The reaction with O-2 led to an unprecedented di-mu-oxo chromium(IV) derivative, [Cr-2{p-Bu(t)calix[4](O)(2)(OMe)(2)}(2)(mu-O-2)] 7, which displays a ferromagnetic coupling between the two d(2) centres. The proposed structures are supported by X-ray analyses of complexes 2-4, 6 and 7.
2000
Chromium-(II) and Chromium-(III) over a Planar Oxo Surface Modelled by Calix[4]arene Anions: Redox Chemistry and Formation of Cr-C Functionalities / J., Hesschenbrouck; E., Solari; C., Floriani; N., Re; Rizzoli, Corrado; A., CHIESI VILLA. - In: DALTON. - ISSN 1470-479X. - ?:(2000), pp. 191-198. [10.1039/a908499a]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11381/1840831
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