Some binding modes of 2-aminopyridine to ruthenium(ii) fragments

Abstract

The bonding modes of 2-aminopyridine (apy) (1 equiv.) with some ruthenium(II) fragments were studied. In the reaction with [RuCp(CH₃CN)₃]⁺ (1) one acetonitrile ligand is replaced with apy being κ¹(N-pyridine) bonded. This complex is very air-sensitive transforming into dinuclear [RuCp(μ³-dapy)]₂²⁺ where dapy is deprotonated apy. On the other hand, [RuCl₂(PPh₃)₃] exchanges one phosphine ligand for apy which is coordinated in the κ²N,N′ mode. Similar to 1, the complexes [RuCp(CH₃CN)₂L]⁺(L = PMe₃, PPh₃ or CO), also react with apy to give [RuCp(CH₃CN)(L)(κ¹N-apy)]⁺. These compounds were reacted with HCCPh with appreciable differences depending on L. While with L = CH₃CN no clean reaction took place, with L = PMe₃ an η³-allyl carbene is formed with release of apy. With L = PPh₃ or CO, dapy stabilizes a Fischer carbene through chelation. Finally, if 1 is reacted with 2-N,N-dimethylaminopyridine (dmapy), all acetonitriles are displaced in favor of η⁶-coordinated dmapy.