The synthesis of an aqua trans-diphosphine complex of ruthenium: crystal structure of trans-[Ru(H 2O)(PEt 3) 2(trpy)](ClO 4) 2· 3H 2O

Abstract

The complexes cis- and trans-[Ru(Cl) 2(PEt 3)- (trpy)], trans-[Ru(Cl)(PEt 3) 2(trpy)](Cl) and [Ru- (L)(PEt 3) 2(trpy)](ClO 4) x (trpy = 2,2′,2′'-terpyridine; L = NO 2, NO, OH 2; x = 1−3) were prepared. A novel synthetic strategy was employed to form the aqua trans-diphosphine complex because of the difficulty of forming it via a direct pathway. Characterization by electronic spectroscopy, electrochemistry and elemental analysis was conducted. The species [Ru(H 2O)(PEt 3) 2(trpy)](ClO 4) 2·3H 2O was further characterized by an X-ray structural analysis and is the first aqua trans-diphosphine complex of ruthenium to be synthesized. The complex [Ru- (H 2O)(PEt 3) 2(trpy)](ClO 4) 2·3H 2O crystallized in the centrosymmetric monoclinic space group P2 1/ c with a = 9.886(5), b = 19.289(7), c = 20.255-(6) Å, β = 92.88(3)° and Z = 4. Diffraction data were collected on a Syntex P2 1 automated diffractometer and the structure refined to R F= 8.8% for all 3407 reflections (R F = 7.5% for those 2771 data with I> 3σ( I)). The structure contains a disordered PEt 3 ligand, highly librating ClO 4 − ions and (possibly) a less than unit occupancy for certain H 2O molecules of solvation. The [Ru(H 2O)(PEt 3) 2(trpy)] 2+ cation has the trpy ligand in mer configuration and mutually trans PEt 3 ligands. Metal-ligand distances are RuN = 2.091(9), 1.952(9), 2.087(8) Å; Ru PEt 3 = 2.405(3), 2.411(4) Å; RuH 2O = 2.218(4) Å.