Synthesis, structure, and reactivity of ruthenium(II) complexes with a hemilabile tetradentate etherdiphosphine ligand

In refluxing toluene the tetradentate ligand (Ph2PCH2CH2OCH2)2 (1) reacts with Cl2Ru(PPh3)3 to give the stable η4-(O,O,P,P)-chelated ruthenium(II) complex trans-Cl2Ru(Ph2PCH2CH2OCH2)2 (2). With carbon monoxide no transformation to an η3-(O,P,P)- or η2-(P,P)-chelated complex accompanied by an uptake of CO takes place. However, if [Cl2Ru(CO)2]n is treated with 1 in a mixture of dichloromethane and 2-methoxyethanol, the η3-(O,P,P)-coordinated ruthenium(II) complex trans-Cl2Ru(CO)(Ph2PCH2CH2OCH2)2 (3) is formed. Attempts to eliminate carbon monoxide from complex 3 to give 2 failed. Also, 3 does not react with further carbon monoxide to form an η2-(P,P)-chelated dicarbonylruthenium(II) complex. Complexes 2 and 3 have been characterized by X-ray structural analyses.