Synthetic, spectral, structural, and catalytic aspects of some piano-stool complexes containing 2-(2-Diphenylphosphanylethyl)pyridine

Abstract

Reactions of the complexes [(η5-C5H 5)Ru(PPh3)2Cl], [{(η6a:rene) Ru(μ-Cl)Cl}2] (η6-arene = C6H 6, C10H14, and C6Me6) and [(η5-C5Me5)M(-Cl)Cl)2] (M = Rh, Ir) with 2-(2-diphenylphosphanylethyl)pyridine (PPh2Etpy) were investigated. Neutral κ1-P-bonded complexes [(η5-C5H5)Ru(κ1-PPPh 2EtPy)(PPh3)Cl] (1) and [(η6-arene] Ru(κ1-P-PPh2EtPy)Cl2 [arene = C 6H6, (2). C10H14, (3), and C 6Me6, (4)] were isolated from the reactions of [(η5-C5H5)Ru(PPh3) 2Cl] and [{(η6-arene)Ru(-Cl)Cl}2] with PPh2EtPy. Treatment of 1-4 with NH4BF4/ NH 4PF6 in methanol allows the synthesis of cationic κ2-P,Nchelated complexes [(η5-C 5H5)Ru(K2-P,N-PPh2EtPy)(PPh 3)]+ (5) and [(η6-arene) Ru(κ2-P-N-PPh2EtPy)Cl]+ [arene = C 6H6, (6), C6H14, (7), and C 6Me6 (6)]. On the other hand, the dimers [{(η5-C5Me5)M(-Cl)Cl}2] (M = Rh or Ir) reacted with PPh2EtPy in methanol to afford cationic κ2-P,N-chelated complexes [(η5-C 5Me5)M(κ2-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 [(η5- C5Me5)Ir(κ1-P-PPh2EtPy)X 2] (X = N3- 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 transferhydrogenation reactions under aqueous conditions. © 2010 Wiley-VCH Verlag GmbH & Co. KGaA,.