- Bridging Fluorides and Hard/Soft Mismatch in d6 and d 8 Complexes: The Case of [TI(μ-F)3Ru(PPh 3)3]
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[RuCl2(PPh3)3] reacts with thallium(I) fluoride to give either [Tl(μ-F)3Ru(PPh3)3] (1) or [Tl(μ3-F)(μ2-Cl)2RU 2(μ2-Cl)-(μ2-F)(PPh3) 4] (2) depending on the excess of TIF used. Both 1 and 2 were fully characterized, including X-ray structure determinations. Complex 1 reacts with dihydrogen to form the known ruthenium hydride complex [Ru-(H) 2(H2)(PPh3)3] upon hydrogenolysis of the Ru-F bond. The reaction of 1 with activated alkyl bromides (R-Br) gives the corresponding alkyl fluorides and the trinuclear complex [Tl(μ 3-F)(μ2-F)(μ2-X)Ru2(μ 2-Br)(μ2-F)(PPh3)4] (X = Br, F) (3), whose structure closely resembles that of 2. However, 1 is not active as catalyst for the nucleophilic fluorination of R-Br in the presence of thallium fluoride. The effect of the bridging coordination mode of fluoride on the Ru-F bond is discussed in terms of the HSAB principle, which suggests a more general model for predicting the stability of d6 and d8 complexes containing hard ligands (such as fluoro, oxo, and amido).
- Becker, Claus,Kieltsch, Iris,Broggini, Diego,Mezzetti, Antonio
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