Di- and linear tri-nuclear carbonyl ruthenium clusters containing asymmetrically bridging 2,7-disubstituted naphthyridines

Abstract

The diruthenium(I) complex cis-[Ru₂(bmnapy)₂(CO)₄]1 was prepared by reaction of 2-benzylamino-7-methyl-1,8-naphthyridine (Hbmnapy) with [Ru₃(CO)₁₂] in benzene. The N¹,N² co-ordination mode of the bridging ligands is supplemented by N⁸ as an axial donor atom. In contrast, the analogous reaction with 7-methyl-1,8-naphthyridin-2-one (Hmonapy) or the corresponding 5-methyl-7-phenyl derivative (Hmopnapy) afforded the respective trinuclear clusters cis-[Ru₃(monapy)₂(CO)₆]2 and cis-[Ru₃(mopnapy)₂(CO)₆]3, which exhibit three-atom chains with 46 valence electrons. X-Ray structural analyses demonstrate that the Ru–Ru bond distance remains effectively unchanged on going from the Ru₂ unit in 1[2.707(1)Å] to the Ru₃ sequence in 3[average 2.701(2)Å], for which an Ru–Ru–Ru angle of 168.6(3)° is observed.