Improved synthesis of the [Ru(eta(6)-p-cymene)Cl-3] anion: Facile isolation under mild conditions

Reaction of [Ru(eta(6)-p-cymene)Cl-2](2) with two equivalents of [(PhP)-P-4][Cl] in CH2Cl2 yields [Ph4P][Ru(eta(6)-p-cymene)Cl-3], containing a trichlororuthenate(II) anion. In solution, an equilibrium between the product and [Ru(eta(6)-p-cymene)Cl-2]2 is observed, which in CDCl3 is nearly completely shifted to the dimer, whereas in CD2Cl2 essentially a 1:1-mixture of the two ruthenium species is present. Crystallization from CH2Cl2/pentane yielded two different crystals, which were identified by X-ray analysis as [Ph4P][Ru(eta(6)-p-cymene)Cl-3] and [Ph4P][Ru(eta(6)-p-cymene)Cl-3]center dot CH2Cl2.