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, Pr^<i>i</i>C₆H₄Me). While the reaction with triphenylphosphine and stannous chloride only gives the neutral mono(trichlorostannyl) complexes [(η⁶-C₆H₆)Ru(PPh₃)(SnCl₃)Cl] (<b>1</b>) and [(η⁶-Pr^<i>i</i>C₆H₄Me)Ru(PPh₃)(SnCl₃)Cl] (<b>2</b>), the neutral di(trichlorostannyl) complex [(η⁶-Pr^<i>i</i>C₆H₄Me)Ru(NCPh)(SnCl₃)₂] (<b>3</b>) 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)]⁺ (<b>5</b>) and of the anionic tris(trichlorostannyl) complex [(η⁶-C₆H₆)Ru(SnCl₃)₃]⁻ (<b>6</b>). On the other hand, [(η⁶-Pr^<i>i</i>C₆H₄Me)Ru(μ₂-Cl)Cl]₂ reacts with SnCl₂ and hexamethylenetetramine hydrochloride or 18-crown-6 to give the anionic di(trichlorostannyl) complex [(η⁶-Pr^<i>i</i>C₆H₄Me)Ru(SnCl₃)₂Cl]⁻ (<b>4</b>), isolated as the hexamethylenetetrammonium salt or the chloro-tin 18-crown-6 salt. The single-crystal X-ray structure analyses of <b>1</b>, <b>2</b>, [(CH₂)₆N₄H][<b>4</b>], [(18-crown-6)SnCl][<b>4</b>] and [<b>5</b>][<b>6</b>] reveal for all complexes a <i>pseudo</i>-tetrahedral piano-stool geometry with ruthenium–tin bonds ranging from 2.56 (anionic complexes) to 2.60 Å (cationic complex).