A d¹⁰ Ni–(H₂) Adduct as an Intermediate in HH Oxidative Addition across a NiB Bond

Abstract

Bifunctional EH activation offers a promising approach for the design of two‐electron‐reduction catalysts with late first‐row metals, such as Ni. To this end, we have been pursuing H2 activation reactions at late‐metal boratranes and herein describe a diphosphine–borane‐supported Ni—(H2) complex, [(PhDPBiPr)Ni(H2)], which has been characterized in solution. 1H NMR spectroscopy confirms the presence of an intact H2 ligand. A range of data, including electronic‐structure calculations, suggests a d10 configuration for [(PhDPBiPr)Ni(H2)] as most appropriate. Such a configuration is highly unusual among transition‐metal H2 adducts. The nonclassical H2 adduct is an intermediate in the complete activation of H2 across the NiB interaction. Reaction‐coordinate analysis suggests synergistic activation of the H2 ligand by both the Ni and B centers of the nickel boratrane subunit, thus highlighting an important role of the borane ligand both in stabilizing the d10 Ni—(H2) interaction and in the H—H cleavage step.

Leveraging molecular metal–support interactions for H2 and N2 activation

“…These dual effects should both further stabilize η 2 -H 2 binding in M−LA relative to the case of a single metal center, M [32]. As a practical consequence, employing Lewis acidic Group 13 metal ions as supports for a transition metal have led to the discovery and isolation of rare η 2 -H 2 adducts of d 10 Ni(0) [38,39]. To date we have not isolated any η 2 -H 2 adducts of M A M B L where M B is a transition metal, and so orbital interactions with H 2 will not be considered here for the case of a supporting transition metal.…”

Synthesis and Platinum Complexes of an Alane‐Appended 1,1′‐Bis(phosphino)ferrocene Ligand

“…[3] Within this area, the vast majority of the research has focused on borane Lewis acids, [4] and has relied upon ambiphilic ligands to stabilize metal-borane interactions, since unsupported metal-borane compounds have thus far evaded isolation.…”

Nickel and Palladium Complexes of Ferrocene-Backbone Bisphosphine-Borane and Trisphosphine Ligands

“…Peters et al have also reported the synthesis of [Ni(N 2 )( iPr DPB Ph )] ( iPr DPB Ph = {o-( i Pr 2 P)C 6 H 4 } 2 BPh), which crystallized with three independent molecules within the unit cell, two of which are [Ni(N 2 )( iPr DPB Ph )] and one of which is [{Ni-( iPr DPB Ph )} 2 (μ-N 2 )]. Similarly to 4, the nickel center in the dimetallic compound is pseudotetrahedral with Ni−N and N− N bond lengths of 1.920 and 1.123 Å, respectively 17. The N N stretching frequency in 4 is 2006 cm −1 , which is shifted to lower frequency relative to the aforementioned [{Ni-(PP R P)} 2 (μ-N 2 )] complexes (ν(NN) = 2045 cm −1 (R = Me) and 2038 cm −1 (R = OMe)).…”