Formation and molecular structure of novel Ru(III) dimers of a symmetric antitumor drug analogue

The symmetrical anionic and neutral dimers [H(TMSO)2]2trans-[{RuCl4(TMSO)}2](μ-pyz) (1), and mer-[{RuCl3(TMSO)2}2](μ-pyz) (2) were isolated by the reaction of [H(TMSO)] trans-[RuCl4(TMSO)2] and mer-[RuCl3(TMSO)3] with heterocyclic nitrogen donor ligand pyrazine (pyz) at room temperature. These complexes can be regarded as unprecedented examples in the general Creutz-Taube family of ruthenium dimers. Each ruthenium center in 1 and 2 has a coordination environment akin to that of known anionic and neutral monomeric Ru(III) complexes. Crystals of 1 · acetone are orange, needle like, space group , a=10.419(3) Å, b=10.539(3) Å, c=12.595(5) Å, α=69.837(16)°, β=69.968(15)°, γ=74.330(15)° and crystals of 2 · 4TMSO are orange prisms, trigonal, space group , a=33.971(5) Å, b=33.971(5) Å, c=12.210(2) Å, α=90°, β=90° and γ=120°.