Bridging Fluorides and Hard/Soft Mismatch in d6and d8Complexes: The Case of [Tl(μ-F)3Ru(PPh3)3]

Abstract
[RuCl2(PPh3)3] reacts with thallium(I) fluoride to give either [Tl(μ-F)3Ru(PPh3)3] (1) or [Tl(μ3-F)(μ2-Cl)2Ru22-Cl)(μ2-F)(PPh3)4] (2) depending on the excess of TlF 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(μ3-F)(μ2-F)(μ2-X)Ru22-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).

This publication has 66 references indexed in Scilit: