The synthesis and crystallographic characterisation of the complexes [RuX(CO)(η2-C,N-C6H5C(H)double bond; length as m-dashNC6H4-4Me)(PPh3)2] · CHCl3 (X = Cl, Br, I, F): Evidence for competing Ru–X⋯Cl–CHCl2 and Ru–X⋯HCCl3 interactions in the solid state

Treatment of [RuCl(CO){η2-C,N-C6H4C(H)double bond; length as m-dashNC6H4-4-Me}(PPh3)2] 2-Cl with Ag[BF4] in acetone/CH2Cl2 gives the cationic complex [Ru{Odouble bond; length as m-dashC(CH3)2}(CO){η2-C,N-C6H4C(H)double bond; length as m-dashNC6H4-4-CH3}(PPh3)2][BF4] (not isolated) which then reacts with NaX (X = F, Br, I) to afford the new compounds [RuX(CO){η2-C,N-C6H4C(H)double bond; length as m-dashNC6H4-4-CH3}(PPh3)2] (X = F, Br, I) 2-F, 2-Br, and 2-I. All of the new compounds have been characterised by elemental analysis (C, H, and N), 1H, 13C–{1H}, 31P{1H} NMR spectroscopy and infrared spectroscopy. The infrared data support the hypothesis of that the fluoride ligand is the strongest halogen π-donor to the metal centre. In addition, the compounds 2-Br · 1.5CHCl3, 2-Cl · CHCl3, 2-I · 1.5CHCl3 have been characterised by single crystal X-ray diffraction studies: 2-Cl shows a rare example of a Ru–Cl⋯ClCHCl2 interaction, whereas 2-Br and 2-I show the expected Ru–X⋯HCCl3 hydrogen bond interactions.