Cooperative double deprotonation of bis(2-picolyl)amine leading to unexpected bimetallic mixed valence (M(-I), M(I)) rhodium and iridium complexes.
Inorg Chem
; 50(16): 7524-34, 2011 Aug 15.
Article
em En
| MEDLINE
| ID: mdl-21749052
ABSTRACT
Cooperative reductive double deprotonation of the complex [Rh(I)(bpa)(cod)](+) ([4](+), bpa = PyCH(2)NHCH(2)Py) with one molar equivalent of base produces the bimetallic species [(cod)Rh(bpa-2H)Rh(cod)] (7), which displays a large Rh(-I),Rh(I) contribution to its electronic structure. The doubly deprotonated ligand in 7 hosts the two "Rh(cod)" fragments in two distinct compartments a "square planar compartment" consisting of one of the Py donors and the central nitrogen donor and a "tetrahedral π-imine compartment" consisting of the other pyridine and an "imine CâN" donor. The formation of an "imine donor" in this process is the result of substantial electron transfer from the {bpa-2H}(2-) ligand to one of the rhodium centers to form the neutral imine ligand bpi (bpi = PyCH(2)NâCHPy). Hence, deprotonation of [Rh(I)(bpa)(cod)](+) represents a reductive process, effectively leading to a reduction of the metal oxidation state from Rh(I) to Rh(-I). The dinuclear iridium counterpart, complex 8, can also be prepared, but it is unstable in the presence of 1 mol equiv of the free bpa ligand, leading to quantitative formation of the neutral amido mononuclear compound [Ir(I)(bpa-H)(cod)] (2). All attempts to prepare the rhodium analog of 2 failed and led to the spontaneous formation of 7. The thermodynamic differences are readily explained by a lower stability of the M(-I) oxidation state for iridium as compared to rhodium. The observed reductive double deprotonation leads to the formation of unusual structures and unexpected reactivity, which underlines the general importance of "redox noninnocent ligands" and their substantial effect on the electronic structure of transition metals.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Idioma:
En
Revista:
Inorg Chem
Ano de publicação:
2011
Tipo de documento:
Article
País de afiliação:
Espanha