Pentamethylcyclopentadienyl ruthenium “pogo stick” complexes with nitrogen donor ligands?

Dalton Transactions Pub Date: 2019-02-28 DOI: 10.1039/C9DT00577C

Abstract

The half-sandwich 1,3-bis(trimethylsilyl)allyl and bis(trimethylsilyl)amido ruthenium complexes [(η5-C5Me5)RuX] (X = η3-C3H3(SiMe3)2, 1; X = N(SiMe3)2, 2) were prepared by reaction of tetranuclear [(η5-C5Me5)RuCl]4 with four equivalents of K[C3H3(SiMe3)2] or Na[N(SiMe3)2]. Complexes 1 and 2 are formally 16- and 14-electron complexes, respectively, and exhibit γ-agostic C–H?Ru interactions in the solid state, which were further investigated by density functional theory (DFT) calculations and quantum theory of atoms in molecules (QTAIM) analysis. The acid–base reaction of the amido complex 2 with 1,3-bis(2,6-diisopropylphenyl)imidazolin-2-imine (ImDippNH) afforded the imidazolin-2-iminato complex [(η5-C5Me5)Ru(NImDipp)] (4); 4 was also obtained from the reaction of [(η5-C5Me5)RuCl]4 with the lithium reagent [(ImDippN)Li]2. 4 represents the first terminal imidazolin-2-iminato complex with a late transition metal and shows a rare one-legged piano stool (“pogo stick”) geometry with a short Ru–N bond of 1.8607(15) ?. The reaction of 4 with tert-butyl isocyanate (tBuNCO) gave the ureato complex [(η5-C5Me5)Ru{ImDippN(C[double bond, length as m-dash]O)NtBu}] (5) by [2 + 2] cycloaddition. This reactivity together with a DFT study on the bonding situation in 4 suggest a close similarity with related half-sandwich imido complexes [(arene)M(NR)] (M = Ru, Os) and [CpM(NR)] (M = Rh, Ir).

Graphical abstract: Pentamethylcyclopentadienyl ruthenium “pogo stick” complexes with nitrogen donor ligands
Recommended Literature