856669-13-1Relevant articles and documents
2 as convenient entry into iron-modified pincer complexes: Bimetallic η6,κ1-POCOP-pincer iron iridium compounds
Walter, Marc D.,White, Peter S.
, p. 1842 - 1854 (2011/10/10)
The synthesis of [(1,2,4-tBu3C5H2)FeI] 2, [Cp′FeI]2 (1), and its reaction chemistry are described. Complex 1 shows remarkable stability toward ligand redistribution in solution and gas-phase due to kinetic stabilization with respect to formation. In coordinating solvents the dimer is homolytically cleaved to form paramagnetic mono-solvate 16 valence-electron (VE) adducts [Cp′FeI(L)]. These solvent adducts are labile, and 1 is re-established on exposure to dynamic vacuum. Complex 1 was demonstrated to be a suitable synthon for [Cp′Fe] + transfer to Ir pincer complexes and successful η6- coordination of this fragment to the arene ring of κ1- metallated POCOP-iridium pincer complexes [(Cp′Fe)(POCOP)Ir(H)(I)] ([5]+) and [(Cp′Fe)(POCOP)Ir(C2H4)] ([7]+) (POCOP = C6H3-2,6-(OPtBu 2)2) was accomplished. In these heterometallic organometallic complexes, the π- and σ-electrons of the POCOP-pincer phenyl anion are involved in η6- and κ1- coordination to iron(ii) and iridium(iii) and iridium(i), respectively. [Cp′Fe]+ coordination alters the charge distribution in the (POCOP)Ir complex by inducing significant charge transfer from the POCOP aryl π-system to the [Cp′Fe]+ fragment, and therefore yielding an electron-poor and more electrophilic iridium center. Density functional theory (DFT) calculations provide a detailed understanding of this effect. Preliminary catalytic studies show that [7]+ is an active catalyst in transfer dehydrogenation between cyclooctane (COA) and tert-butyl ethylene (TBE).
