Synthesis, structure, photophysical and electrochemical behavior of 2-amino-anthracene triosmium clusters.
Inorganica Chim Acta
; 361(6): 1624-1633, 2008 May 05.
Article
em En
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| ID: mdl-31607757
ABSTRACT
The reactions of 2-amino-anthracene with [Os3(CO)10(CH3CN)2] have been studied and the products structurally characterized by spectroscopic, X-ray diffraction, photophysical and electrochemical techniques. At room temperature in CH2Cl2 two major, isomeric products are obtained [Os3(CO)10(µ-η2-(N-C(1))-NH2C14H8)(µ-H)] (1, 14%) and [Os3(CO)10(µ-η2-(N-C(3))-NHC14H9)(µ-H)] (2, 35%) along with a trace amount of the dihydrido complex [Os3(CO)9(µ-η2-(N-C(3))-NHC14H8)(µ-H)2] (3). In refluxing tetrahydrofuran only complexes 2 and 3 are obtained in 24% and 28%, respectively. A separate experiment shows that complex 1 slowly converts to 2 and that the rearrangement is catalyzed by adventitious water and involves proton transfer to the anthracene ring. Complex 1 is stereochemically non-rigid; exhibiting edge to edge hydride migration while 2 is stereochemically rigid. Complex 3 is also stereochemically non-rigid showing a site exchange process of the magnetically nonequivalent hydrides typical for trinuclear dihydrides. Interestingly, 2 decarbonylates cleanly to the electronically unsaturated 46e- cluster [Os3(CO)9(µ3-η2-(N-C(3))-NHC10H9)(µ-H)] (4, 68%) in refluxing cyclohexane, while photolysis of 2 in CH2Cl2 yields only a small amount of 3 along with considerable decomposition. The mechanism of the conversion of 1 to 2 and the dependence of the product distribution on solvent are discussed. All four compounds are luminescent with compounds 1-3 showing emissions that can be assigned to radiative decay associated with the anthracene ligand. Complexes 1-3 all show irreversible 1e- reductions in the range of-1.85-2.14 V while 4 shows a nicely reversible 1e- wave at-1.16 V and a quasi-reversible second 1e- wave at-1.62 V. Irreversible oxidations are observed in the range from +0.35 to +0.49 V. The relationship between the cluster ligand configurations and the observed electrochemical and photochemical behavior is discussed and compared with that of the free ligand.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Idioma:
En
Revista:
Inorganica Chim Acta
Ano de publicação:
2008
Tipo de documento:
Article
País de afiliação:
Estados Unidos