Bimetallic ruthenium-tin chemistry: Synthesis and molecular structure of arene ruthenium complexes containing trichlorostannyl ligands

A series of neutral, anionic and cationic arene ruthenium complexes containing the trichlorostannyl ligand have been synthesised from SnCl₂ and the corresponding arene ruthenium dichloride dimers [(η⁶-arene)Ru(μ₂-Cl)Cl]₂ (arene = C₆H₆, PrⁱC₆H₄Me). While the reaction with triphenylphosphine and stannous chloride only gives the neutral mono(trichlorostannyl) complexes [(η⁶-C₆H₆)Ru(PPh₃)(SnCl₃)Cl] (1) and [(η⁶-PrⁱC₆H₄Me)Ru(PPh₃)(SnCl₃)Cl] (2), the neutral di(trichlorostannyl) complex [(η⁶-PrⁱC₆H₄Me)Ru(NCPh)(SnCl₃)₂] (3) could be obtained for the para-cymene derivative with benzonitrile as additional ligand. By contrast, the analogous reaction with the benzene derivative leads to a salt composed of the cationic mono(trichlorostannyl) complex [(η⁶-C₆H₆)Ru(NCPh)₂(SnCl₃)]⁺ (5) and of the anionic tris(trichlorostannyl) complex [(η⁶-C₆H₆)Ru(SnCl₃)₃]⁻ (6). On the other hand, [(η⁶-PrⁱC₆H₄Me)Ru(μ₂-Cl)Cl]₂ reacts with SnCl₂ and hexamethylenetetramine hydrochloride or 18-crown-6 to give the anionic di(trichlorostannyl) complex [(η⁶-PrⁱC₆H₄Me)Ru(SnCl₃)₂Cl]⁻ (4), isolated as the hexamethylenetetrammonium salt or the chloro-tin 18-crown-6 salt. The single-crystal X-ray structure analyses of 1, 2, [(CH₂)₆N₄H][4], [(18-crown-6)SnCl][4] and [5][6] reveal for all complexes a pseudo-tetrahedral piano-stool geometry with ruthenium-tin bonds ranging from 2.56 (anionic complexes) to 2.60 Å (cationic complex).