A study of the coordination ability of 2,5-di(2-pyridyl)phospholes on Ru centres

Abstract The coordination behaviour of the readily available 1-phenyl-2,5-di(2-pyridyl)phosphole (NPN) toward Ru centres was investigated. Neutral and ionic compounds of formula [RuCl( p -cymene)(NPN)]TfO (TfO=CF 3 SO 3 )… ( 1 ), [RuCl( p -cymene)(NPN)]BF 4 ( 2 ), [RuCl(C 6 Me 6 )(NPN)]TfO ( 3 ), RuCp′Cl(NPN) [Cp′=C 5 H 5 ( 4 ), C 5 Me 5 ( 5 )], Ru(C 5 Me 5 )(σ 1 -C 8 H 13 )(NPN) ( 6 ), RuCl 2 (NPN) 2 ( 7 ) and RuClH(cod)(NPN) (cod=1,5-cyclooctadiene) ( 8 ) were obtained. Two diastereomers were obtained for 1 , 2 and 4 , ( a , b ) while three were found in the case of 8 ( a – c ). According to NMR spectroscopy, the 2,5-bis(2-pyridyl)phosphole acts as a 1,4- P , N chelate ligand in all cases. This behaviour was confirmed by an X-ray diffraction study performed on complex 1a . Proton transfer studies on complex 8 demonstrated the influence of the molecular structure on the ability to form dihydrogen bridges.