Making a 16-electron bromo (or iodo) complex of ruthenium(II) and a C-F bond in one pot

The 16e(-) bromo or iodo complexes [RuX(dppp)(2)](+) (dppp = 1,3-bis(diphen ylphosphino)propane, X = Br (1c), I (1d)) and [RuX(dppe)(2)](+) (dppe = 1,2 -bis(diphenylphosphino)ethane, X = Br (2c), I (2d)) have been prepared expl oiting the reaction of the fluoro complexes [RuF(dppp)(2)](+) (1a) and [Tl( mu -F)(2)Ru(dppe)(2)](+) (3) with activated alkyl bromides or iodides. The X-ray structures of 1c, 1d, 2c, and 2d suggest that the distortion of the Y -shaped trigonal-bipyramidal structure of [MX(P-boolean AND P)(2)](+) is po ssibly related to the formation of intramolecular hydrogen bonds between th e halide ligand and the ortho-hydrogen atoms of the neighbouring phenyl rin gs. The five-coordinate species 1c, 1d, 2c, and 2d react with H-2 to form t he dihydrogen complexes [RuX(eta (2)-H-2)((PP)-P-boolean AND)(2)](+). The r eaction of the dppp derivatives 1c and 1d with H-2 (P = 1 atm, 1 atm = 101. 322 kPa) is an equilibrium. Quantitative formation of [RuBr(eta (2)-H-2)(dp pp)(2)] (4c) is obtained under H-2 pressure (100 bar, 1 bar = 100 kPa), whe reas the iodo analogue is not stable under analogous conditions. The less c rowded dppe derivatives 2c and 2d react quantitatively with H-2 under ambie nt pressure. The iodo and bromo derivatives [RuX(eta (2)-H-2)((PP)-P-boolea n AND)(2)](+) contain elongated dihydrogen ligands, as indicated by their t ransverse relaxation times T-1 (min). The present data suggest that Cl, Br, and I have similar donor properties in these dihydrogen complexes, and tha t the different chemical behaviour in the Cl, Br, I series is mainly a resu lt of steric effects.