Synthetic, structural and reactivity studies of indenyl ruthenium complexes

Abstract

The chemistry of indenyl ruthenium complexes has been investigated, starting from the easily synthesized complexes, [(I?5-Ind)Ru(PPh3)2Cl] 1 (Ind = C9H7). Phosphine substitution with ferrocenyl-diphosphine ligands, 1,1a??-bis(diphenylphosphino)ferrocene (dppf) and (R)-(S)-Josiphos, gave [(I?5-Ind)Ru(dppf)Cl] 3 and [(I?5-Ind)Ru[(R)-(S)-Josiphos]Cl] 5. The dependence of the rate of epimerization in the Cp (Cp = C5H5) analogue of 5 on the concentration of free (R)-(S)-Josiphos was also investigated.The dppf derivative, 3, was then reacted with different coordinating donor ligands: (i) S-containing ligands (thiolates, dithiolates, heterocyclic thiolates); (ii) mixed donor ligand (SCH2CH2PPh2)-; (iii) [Co(CO)4]- and (iv) azide. The azide derivative was found to undergo cycloaddition with dimethyl acetylenedicarboxylate. The lability of the indenyl ligand was observed to be affected by the nature of the co-ligands, i.e. dppf, dppm and CO. A general synthetic methodology had been developed for the tethered [(I?5,I?1-IndCH2CH2PPh2)Ru] complexes with various donor ligands via a reductive elimination of the bis(allyl) ligand in [(I?3,I?3-C10H16)Ru(I?1P-IndCH2CH2PPh2)Cl2].Most of the new complexes synthesized have been characterized by X-ray diffraction analyses. [(Ind)Ru(CO)]2 and [(Ind)Ru(diphos)(S-containing ligand)] (diphos = dppf, dppm) were found to be catalytically active in homo-coupling of PhCa?!CH. [(Ind)Ru(CO)2] also catalyzed cross-coupling reaction between terminal alkynes and carboxylic acids.