From μ3- to μ- agostic methyl coordination: NMR and solid state study of donor ligands uptake by the triangular cluster anion [Re3(μ-H)3(μ3-CH3)(CO)9]- [From mu(3)- to mu- agostic methyl coordination: NMR and solid state study of donor ligands uptake by the triangular cluster anion [Re-3(mu-H)(3)(mu(3)-CH3) (CO)(9)](-)]
Articolo
Data di Pubblicazione:
2022
Citazione:
From μ3- to μ- agostic methyl coordination: NMR and solid state study of donor ligands uptake by the triangular cluster anion [Re3(μ-H)3(μ3-CH3)(CO)9]- [From mu(3)- to mu- agostic methyl coordination: NMR and solid state study of donor ligands uptake by the triangular cluster anion [Re-3(mu-H)(3)(mu(3)-CH3) (CO)(9)](-)] / D. Maggioni, D. Tunzi, P. Illiano, P. Mercandelli, A. Sironi, T. Beringhelli, L. Carlucci, G. D'Alfonso, M. Panigati. - In: INORGANICA CHIMICA ACTA. - ISSN 0020-1693. - 529(2022 Jan 01), pp. 120641.1-120641.10. [10.1016/j.ica.2021.120641]
Abstract:
[Re3(μ-H)3(μ3-CH3)(CO)9]- (1) reacts with CO at 273 K to quantitatively give the [Re3(μ-H)3(μ-CH3)(CO)10]- derivative (2) through the conversion of the methyl
group from triply to doubly-bridging coordination. An NMR isotopic perturbation experiment demonstrates the unsymmetrical bridging of the methyl group on the
Re-Re bond, and a fast exchange, in solution, between one agostic and two terminal C–H bonds. This is in agreement with X-Ray diffraction analysis performed on
single crystals of 2. In solution at room temperature 2 decomposes with CH4 elimination, which is also observed when 2 is treated with CO affording the [Re3(μ-
H)2(CO)12]- anion. The opening of the triple bridging methyl coordination in 1 occurs also with other different L ligands, yielding to the syn and anti isomers of
unsymmetrically bridged methyl complexes of general formula [Re3(μ-H)3(μ-CH3)(CO)9(L)]- (L = MeCN, PMePh2, THF). The kinetic and thermodynamic stabilities of
these isomers vary with the nucleophilicity of the ligand and the polarity of the solvent. In particular, the strong nucleophile PMePh2 affords the quantitative
conversion of anion 1 into the thermodynamic syn isomer, which is stable in THF at room temperature for several days. On the contrary, weak nucleophiles, such as
MeCN or THF, give equilibrium mixtures containing residual amounts of anion 1. The adducts with MeCN are stable in solution at room temperature for several
hours, while decompose fastly in neat MeCN affording mainly the cluster anion [Re3(μ-H)4(CO)9(MeCN)]-. This suggests that cluster stabilization after methane
evolution follows a different path with respect to that observed in the reaction of 1 with CO.
Tipologia IRIS:
01 - Articolo su periodico
Elenco autori:
D. Maggioni, D. Tunzi, P. Illiano, P. Mercandelli, A. Sironi, T. Beringhelli, L. Carlucci, G. D'Alfonso, M. Panigati
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