Synthetic, Spectral, Structural, and Catalytic Aspects of Some Piano-Stool Complexes Containing 2-(2-Diphenylphosphanylethyl)pyridine

Reactions of the complexes [(eta(5)-C5H5)Ru(PPh3)(2)Cl], [{eta(6)-arene)Ru(mu-Cl)Cl}(2)] (eta(6)-arene = C6H6, C10H14, and C6Me6) and [{(eta(5)-C5Me5)M(mu-=Cl)Cl}(2)] (M = Rh, Ir) with 2-(2-diphenylphosphanylethyl)pyridine (PPh(2)Etp) were investigated. Neutral kappa(1)-P-bonded complexes [(eta(5)-C5H5)Ru(kappa(1)-P-PPh2EtPy)(PPh3)Cl] (1) and (eta(6)-arene)Ru(kappa(1)-P-PPh2EtPy)Cl-2] [arene = C6H6. [2]. C10H14, (3), and C6Me6, (4)] were isolated from the reactions of [(eta(5)-C5H5)Ru(PPh3)(2)Cl], [{eta(6)-arene)Ru(mu-Cl)Cl}(2)] with PPh2EtPy. Treatment of 1-4 with NH4BF4/NH4PF6 in methanol allows the synthesis of cationic kappa(2)-P,N-chelated complexes [(eta(5)-(CH5)-H-5)Ru(kappa(2)-PN-PPh2EtPy)(PPh3)](+) (5) and [(eta(6)-arene)Ru (kappa(2)-P-N-PPh2EtPy)Cl](+) [arene = (CH6)-H-6, (6), C6H14, (7), and C6Me6 (8)]. On the other hand, the dimers [{(eta(5)-C5Me5)M(mu-Cl)Cl}(2)] (M = Rh or Ir) reacted with PPh2EtPy in methanol to afford cationic kappa(2)-P,N-chelated complexes [(eta(5)-C5Me5)M(kappa(2)-P-N-PPh2EtPy)Cl](+) [M = Rh, (9); Ir, (10)]. Complex 10 reacted with an excess amount of sodium azide or sodium chloride to afford the complexes [(eta(5)-C5Me5)-Ir(kappa(1)-P-PPh2EtPy)X-2] (X = N-3(-) 11; Cl-, 12), establishing the hemilabile nature of the coordinated PPh2EtPy. The complexes were characterized by elemental analyses and various physicochemical techniques. The molecular structures of 1, 5, 6, 9, and 10 were determined crystallographically, and the catalytic potentials of 1-10 were evaluated towards transfer-hydrogenation reactions under aqueous conditions.