First examples of neutral and cationic indenyl nickel(ii) complexes bearing arsine or stibine ligands: highly active catalysts for the oligomerisation of styrene

Abstract

New indenyl nickel(ii) complexes bearing arsine or stibine ligands synthesised by a new methodology exhibit very high catalytic activities for the oligomerisation of styrene.

Cationic R‐Substituted‐Indenyl Nickel(II) Complexes of Arsine and Stibine Ligands: Synthesis, Characterization, and Catalytic Behavior in the Oligomerization of Styrene

“…The cationic η‐indenyl nickel(II) complexes bearing arsine or stibine donor ligands 1 – 9 (Scheme ) were synthesized by the method reported previously, whereby the starting materials [Ni(η‐R n ‐Ind) 2 ] I – V (Scheme ), were protonated with a stoichiometric amount of HBF 4 , at low temperature, in the presence of two equivalents of the suitable EPh 3 (E = As, Sb) donor ligand, leading to the corresponding cationic η‐R n ‐indenyl nickel(II) complexes in moderate to very high yields (53–96 %). Although complexes 1 and 2 were already reported in our earlier communication, they were also included in this full paper for comparison reasons, in terms of structure and catalysis.…”

“…[4f], , , We then used our methodology to prepare a cationic Ind nickel complex containing simultaneously an As and a Sb donor ligand. The reaction of [Ni(η‐Ind)(AsPh 3 )Cl] with 1.1 equiv. of TlBF 4 , in the presence of 1 equiv.…”

“…In this work, we report the preparation and structural characterization of a family of new cationic Ni II complexes of this type bearing now substituted η–R n – indenyl ligands (e.g. 1‐Me‐Ind, 2‐Me‐Ind, 1‐SiMe 3 ‐Ind and 1,3‐Me 2 ‐Ind), thus extending the very scarce number of reported indenyl Ni II complexes containing arsine and stibine ligands , . The impact of the indenyl substitution in their behavior as catalysts for the oligomerization of styrene is evaluated, by comparing their activities with the ones obtained with the unsubstituted indenyl nickel(II) analogues.…”

“…We have been interested in the chemistry of η‐indenyl nickel(II) complexes due to their potential role as oligo‐/polymerization catalysts,, having described an efficient method for the synthesis of the first ever reported cases of indenyl nickel(II) complexes containing arsine or stibine donor ligands (Scheme , A and B , respectively) . The method consisted in the protonation of bis(indenyl)nickel with one equivalent of HBF 4 , in the presence of the appropriate ligands, enabling the preparation of the expected Ni II complexes in high yields.…”

Syntheses, Structures, and Characterization of Nickel(II) Stibines: Steric and Electronic Rationale for Metal Deposition

“…In an effort to better comprehend and optimize catalysis, phosphine ligands and their corresponding organic substituents have been studied for both steric and electronic effects. , Concerning heavier phosphorus group ligands, there have been studies on the relative steric and electronic effects in stand-alone antimony molecules, , but there are few extensive studies regarding the steric, electronic, magnetic, and spectroscopic properties of antimony–nickel (or other 3 d metal) complexes. − Such studies would provide a base of understanding for the design and synthesis of functional antimony-based complexes. Indeed, antimony ligands have proven to be effective donors to metal centers under certain conditions, , and productive catalysts that utilize antimony ligands have already been reported. − …”