An Isolable Mononuclear Palladium(I) Amido Complex

Abstract

Mononuclear Pd­(I) species are putative intermediates in Pd-catalyzed reactions, but our knowledge about them is limited due to difficulties in accessing them. Herein, we report the isolation of a Pd­(I) amido complex, [(BINAP)­Pd­(NHArTrip)] (BINAP = 2,2′-bis­(diphenylphosphino)-1,1′-binaphthalene, ArTrip = 2,6-bis­(2′,4′,6′-triisopropylphenyl)­phenyl), from the reaction of (BINAP)­PdCl2 with LiNHArTrip. This Pd­(I) amido species has been characterized by X-ray crystallography, electron paramagnetic resonance, and multiedge Pd X-ray absorption spectroscopy. Theoretical study revealed that, while the three-electron–two-center π-interaction between Pd and N in the Pd­(I) complex imposes severe Pauli repulsion in its Pd–N bond, pronounced attractive interligand dispersion force aids its stabilization. In accord with its electronic features, reactions of homolytic Pd–N bond cleavage and deprotonation of primary amines are observed on the Pd­(I) amido complex.

On the Synthesis of a T‐Shaped Imido Nickel Complex and Trigonal Amido Nickel Complexes

“…This hinted to the intermediate presence of the benzyl radical that might be result of direct one‐electron reduction of [NiL 2 ] via single electron transfer (SET), or homolytic bond cleavage of a transient nickel(II) benzyl complex ([NiL 2 (CH 2 Ph)] − ). Similar reduction of a palladium(II) complex by homolytic Pd−N bond cleavage of an amido ligand was recently described, as well as the aminyl type behavior of copper or rhodium bound amides [48–51] . Alternativly, the role of A M R species (e. g. KO t Bu) as direct one‐electron reductants is widely accepted for organic substrates, which is known to occur via an inner‐sphere SET [52–54] .…”

“…Similar reduction of a palladium(II) complex by homolytic PdÀ N bond cleavage of an amido ligand was recently described, as well as the aminyl type behavior of copper or rhodium bound amides. [48][49][50][51] Alternativly, the role of A M R species (e. g. KO t Bu) as direct one-electron reductants is widely accepted for organic substrates, which is known to occur via an inner-sphere SET. [52][53][54] A similar mechanism would also is plausible for the reduction of [NiL 2 ] whereas its reduction by A M R would by-pass the formation of stable adducts of the type [Ni(R)L 2 ] À .…”

Dispersion Stabilizes Metal–Metal Bonds in the 1,8-Bis(silylamido)naphthalene Ligand Environment

“…While steric bulk and associated steric clashes are well studied in organometallic chemistry, the importance of dispersion has only recently been recognized. For example, the London dispersion stabilization from bulky aryl and alkyl substituents has been found to be key in enabling the isolation of very reactive organometallic compounds and predicting reactivity. ,− Similar studies have also been undertaken for carbene and phosphine ligands. − By comparison, few investigations have systematically and explicitly considered bond stabilization due to London dispersion in complexes featuring bulky amide ligands, despite the prevalence of these ligands in coordination chemistry. − …”

Palladium Terminal Imido Complexes with Nitrene Character

“…The stoichiometric reaction proceeds slowly at room temperature (17% conversion after 4 days), yet a quantitative yield was obtained after heating to 60 °C under catalytic conditions (10 mol % 1 or 2 ). To probe for long-lived radical intermediates, EPR spectroscopy was employed, yet no such signatures were detected. Peculiar reactivity was observed for 3 , which gave isobutylene in 30% spectroscopic yield (Scheme e) .…”