Premium
Lewis Acid‐Promoted Oxidative Addition at a [Ni 0 (diphosphine) 2 ] Complex: The Critical Role of a Secondary Coordination Sphere
Author(s) -
Zurakowski Joseph A.,
Austen Brady J. H.,
Dufour Maeve C.,
Spasyuk Denis M.,
Nelson David J.,
Drover Marcus W.
Publication year - 2021
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.202103121
Subject(s) - chemistry , coordination sphere , reactivity (psychology) , lewis acids and bases , borane , oxidative addition , adduct , medicinal chemistry , catalysis , coordination complex , ligand (biochemistry) , stereochemistry , organometallic chemistry , hydride , crystallography , metal , crystal structure , organic chemistry , medicine , biochemistry , alternative medicine , receptor , pathology
Oxidative addition represents a critical elementary step in myriad catalytic transformations. Here, the importance of thoughtful ligand design cannot be overstated. In this work, we report the intermolecular activation of iodobenzene (PhI) at a coordinatively saturated 18‐electron [Ni 0 (diphosphine) 2 ] complex bearing a Lewis acidic secondary coordination sphere. Whereas alkyl‐substituted diphosphine complexes of Group 10 are known to be unreactive in such reactions, we show that [Ni 0 (P 2 B Cy 4 ) 2 ] (P 2 B Cy 4 =1,2‐ bis (di(3‐dicyclohexylboraneyl)‐propylphosphino)ethane) is competent for room‐temperature PhI cleavage to give [Ni II (P 2 B Cy 4 )(Ph)(I)]. This difference in oxidative addition reactivity has been scrutinized computationally – an outcome that is borne out in ring‐opening to provide the reactive precursor – for [Ni 0 (P 2 B Cy 4 ) 2 ], a “boron‐trapped” 16‐electron κ 1 ‐diphosphine Ni(0) complex. Moreover, formation of [Ni II (P 2 B Cy 4 )(Ph)(I)] is inherent to the P 2 B Cy 4 secondary coordination sphere: treatment of the Lewis adduct, [Ni 0 (P 2 B Cy 4 ) 2 (DMAP) 8 ] with PhI provides [Ni II (P 2 B Cy 4 ) 2 (DMAP) 8 (I)]I via iodine‐atom abstraction and not a [Ni II (Ph)(I)(diphosphine)] compound – an unusual secondary sphere effect. Finally, the reactivity of [Ni 0 (P 2 B Cy 4 ) 2 ] with 4‐iodopyridine was surveyed, which resulted in a pyridyl‐borane linked oligomer. The implications of these outcomes are discussed in the context of designing strongly donating, and yet labile diphosphine ligands for use in a critical bond activation step relevant to catalysis.