Facile insertion of CO2 into the Ru-H bonds of Ru(dmpe)(2)H-2 (dmpe equals Me(2)PCH(2)CH(2)PMe(2)): Identification of three ruthenium formate complexes

The reaction of cis-Ru(dmpe)(2)H-2 (dmpe = Me(2)PCH(2)CH(2)PMe(2)), 1, with carbon dioxide has been investigated. Addition of CO2 at 293 K results in the formation of two formate complexes: the major product is the trans formate hydride, trans-Ru(dmpe)(2)(OCHO)H, 2, while the minor species is the bis(formate) complex, cis-Ru(dmpe)(2)(OCHO)(2), 3. When the addition of carbon dioxide is performed at 195 K, both the bis(formate) and the cis-formate hydride complex, cis-Ru(dmpe)(2)(OCHO)H, 4, are observed in larger concentrations. All three complexes have been characterized by multinuclear NMR while 2 has been isolated and characterized by X-ray crystallography. The ruthenium formate group is planar with Ru-O(1) = 2.243(4) Angstrom. The Ru-O(1) vector is tilted away from the normal to the P-4 plane with resultant O(1)-Ru-P angles of 84.4(2), 88.4(1), 96.7(1), and 101.5(2)degrees. The C-O(2) vector of the formate group points toward the RuP4 plane. The symmetric and antisymmetric OCO stretching modes in the IR spectrum of 2 were identified by reaction with (CO2)-C-13.