Synthesis, Structure, and Reactivity of Ruthenium(II) Terminal Imido Complexes

The reactions of [(η⁶-cymene)RuCl₂]₂ and [(η⁶-C₆Me₆)RuCl₂]₂ with LiNH−R (R = 2,6-diisopropylphenyl (Ar), 2,6-dimethylphenyl (Ar‘), 2,4,6-tri-tert-butylphenyl (Ar*)) lead to a number of different products depending on the nature of ligands employed. The addition of 2 equiv of LiNHAr to [(η⁶-C₆Me₆)RuCl₂]₂ gives the amido complex (η⁶-C₆Me₆)RuCl(NHAr). Reaction of 4 equiv of the lithium amides with the ruthenium complex [(η⁶-cymene)RuCl₂]₂ or [(η⁶-C₆Me₆)RuCl₂]₂ yields imido complexes. The steric bulk of the substituents on either the η⁶-arene or nitrogen influence the structure of the final product. Large ligands such as the η⁶-C₆Me₆ or the Ar* group prevent the formation of bridged complexes, while combinations of ligands which have smaller steric requirements give dimeric compounds. The structures of (η⁶-cymene)RuCl₂(NH₂Ar), (η⁶-C₆Me₆)RuCl(NHAr), and [(η⁶-cymene)Os(NAr)]₂ are presented and discussed in relation to the previously reported structures of [(η⁶-cymene)Ru(NAr)]₂ and (η⁶-cymene)Ru(⋮NAr*).