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Título

Synthesis and characterization of new paramagnetic tetraaryl derivatives of chromium and molybdenum

AutorAlonso, Pablo J.; Forniés, Juan ; García-Monforte, M. Ángeles ; Martín, Antonio ; Menjón, Babil ; Rillo, Conrado
Palabras claveOrganochromium
Organomolybdenum
Homoleptic compounds
EPR spectroscopy
Cyclic voltammetry
Electronic exchange
Fecha de publicaciónjul-2007
EditorElsevier
CitaciónJournal of Organometallic Chemistry 692(15): 3236-3247 (2007)
ResumenThe low-temperature reaction of [CrCl3(thf)3] with LiC6H3Cl2-2,6 yields the organochromium(III) compound [Li(thf)4][CrIII(C6H3Cl2-2,6)4] (1) in 48% yield. The homoleptic, anionic species [CrIII(C6H3Cl2-2,6)4]− is electrochemically related to the neutral one [CrIV(C6H3Cl2-2,6)4] (2) through a reversible one-electron exchange process (E1/2 = 0.16 V, ΔEp = 0.09 V, ipa/ipc = 1.18). Compound 2 was isolated in 74% yield by chemical oxidation of 1 with [N(C6H4Br-4)3][SbCl6]. Attempts to prepare the salt [NBu4][CrIII(C6Cl5)4] (4) by direct arylation of [CrCl3(thf)3] with LiC6Cl5 in the presence of [NBu4]Br gave the organochromium(II) salt [NBu4]2[CrII(C6Cl5)4] (3) instead, as the result of a reduction process. The salt [NBu4][CrIII(C6Cl5)4] (4) was cleanly prepared by comproportionation of 3 and [CrIV(C6Cl5)4]. The reaction of [MoCl4(dme)] with LiC6Cl5 in Et2O solution proceeded with oxidation of the metal center to give the paramagnetic (S = 1/2), five-coordinate salt [Li(thf)4][MoVO(C6Cl5)4] (5). The crystal and molecular structures of 1 and 2 have been established by X-ray diffraction methods. The magnetic properties of 1 and 4 (S = 3/2) as well as those of 2 (S = 1) have been established by EPR spectroscopy as well as by ac and dc magnetization measurements.
Descripción12 pages, 10 figures, 5 tables, 2 schemes, 1 appendix.
Versión del editorhttp://dx.doi.org/10.1016/j.jorganchem.2007.03.028
URIhttp://hdl.handle.net/10261/19595
DOI10.1016/j.jorganchem.2007.03.028
ISSN0022-328X
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