Synthesis, Reactivities, and Catalytic Properties of Iodo-Bridged Polymeric Iridium Complexes with Flexible Carbon Chain-Bridged Bis(tetramethylcyclopentadienyl) Ligands

Oxidatively-induced C(sp3)-C(sp3) bond formation at a tucked-in iron(iii) complex

Carbon-carbon (C-C) bond formation is a cornerstone of synthetic chemistry, relying on routes such as transition-metal mediated cross-coupling for the introduction of new carbon-based functionality. For {[M] n+-C} (M = metal) structural units, studies that offer well-defined relationships between metal oxidation state, hydrocarbon strain, and {[M] n+-C} bond thermochemistry are thus informative, providing a means to reliably access new product classes. Here, we show that one-electron oxidation of the iron tucked-in complex [(η6-C5Me4[double bond, length as m-dash]CH2)Fe(dnppe)] (dnppe = 1,2-bis(di-n-propylphosphino)ethane) results in C(sp3)-C(sp3) bond formation giving unique {Fe2} dimers. Freeze-quenched CW X-band EPR spectroscopy allowed for spectroscopic identification of the reactive [(η6-C5Me4[double bond, length as m-dash]CH2)Fe(dnppe)]+ intermediate. Density functional theory (DFT) calculations reveal a primarily Fe-centered radical and a weak {[Fe]-C} bond (BDE[Fe]-C = 24.5 kcal mol-1, c.f. BDEC-C(ethane) = 90 kcal mol-1). For comparison, a structurally analogous Fe(iii) methyl complex was prepared, [Cp*Fe(dnppe)(CH3)]+ (Cp* = C5Me5 -), where C(sp3)-C(sp3) coupling was not observed, consistent with a larger calculated BDE[Fe]-C value of 47.8 kcal mol-1. These data are analogized to the simple hydrocarbons ethane and cyclopropane, where a strain-induced BDEC-C decrease of 33 kcal mol-1 is witnessed on cyclization.

Ruthenium-Catalyzed Selective Mono N-Ethylation of Arylamines and Tandem Reduction/N-Ethylation of Nitroarenes Using Triethylamine and Formic Acid

The mono N-alkylation of arylamines using alkylamines as alkyl group donors has been scarcely investigated. In this work, we report the mono N-alkylation of several arylamines (52-95%) catalyzed by the complex ruthenium-triphos in the presence of Al(OTf)3. Moreover, the highly reductant ability of the catalyst system allows the tandem reduction/N-alkylation of nitrobenzenes in good yields (up to 80%). In addition, the catalyst can be recycled after three reaction cycles without loss of catalyst activity.

A Bis-Cyclopentadienyl Ligand-Supported Di-Iron Trihydride Motif as a Synthon for Access to Heterobimetallic Trinuclear Complexes

Herein, we report the synthesis of a flexible bis-cyclopentadienyl ligand L (the doubly deprotonated form of H2L (1,3-bis(2,4-di-tert-butylcyclopentadienyldimethylsilyl)benzene)), demonstrating its ability to stabilize a series of di-iron hydrido complexes. Notably, this ligand facilitates the isolation of an unprecedented anionic cyclopentadienyl ligand-supported di-iron trihydride complex, LFe2(μ-H)3Li(THF) (2), functioning as a synthon for the [Fe2(μ-H)3]- core and providing access to heterobimetallic complexes 4-6 with coinage metals.