Controlled vinyl‐type polymerization of norbornene with a Nickel(II) diphosphinoamine/methylaluminoxane catalytic system

Abstract

A novel nickel-based complex coordinated with an asymmetric diphosphinoamine ligand was synthesized and fully characterized. Single crystals of good quality were also obtained, and the solid-state structure of the complex was studied via X-rays diffraction. The catalytic activity of this Ni(II) complex in the vinyl-type polymerization of norbornene was studied with methylaluminoxane (MAO) as the cocatalyst/activator. The influence of the reaction time, the equivalents of MAO used, and the concentration of the monomer on: (i) the activity of the catalytic system; (ii) the isolated yield of the polymer; and (iii) the molecular weight and molecular weight distribution of the polymer were investigated. The isolated polynorbornene (PNB) yields are significantly higher compared with those reported for other similar nickelbased systems. The as-obtained PNBs are characterized by high molecular weights and relatively narrow and monomodal molecular weight distributions (amongst the narrowest reported in the literature). The linear dependence of the molecular weight of the obtained PNB on the concentration of norbornene points toward a controlled polymerization reaction.

Synthesis and Spectroscopic Properties of PdII and PtII Complexes with Monosulfide and Monoselenide Bis(phosphanyl)amine Ligands

“…The longer Ni–Cl bond is trans to the shorter Ni–P bond, which is in agreement with a trans effect of the phosphine. It is noted that the Ni complex 8 may be potentially used as a catalyst in various synthetic transformations as deduced from the X‐ray data obtained such as bite angle which may be used as a criteria indicative of catalytic activity based on X‐ray data obtained for related Ni complexes 21–25. The aromatic rings 8 as expected have usual bond lengths and angles.…”

Structurally Diverse Metal Coordination Compounds, Bearing Imidodiphosphinate and Diphosphinoamine Ligands, as Potential Inhibitors of the Platelet Activating Factor

“…The crystallographic structures of Cu(O,O) 2 [33], Zn(O,O) 2 [34], Ga(O,O) 3 [36] and Ni(P,P)Cl 2 [37], as well as the (OPPh 2 )(OPPh 2 )NH ligand [41] have been already described (Figures 1–5). A variety of metal core geometries is demonstrated: Cu(O,O) 2 and Ni(P,P)Cl 2 are square-planar, whereas Zn(O,O) 2 is tetrahedral and Ga(O,O) 3 is octahedral.…”

“…The following complexes were prepared according to published procedures: [Cu{(OPPh 2 )(OPPh 2 )N- O , O } 2 ] [33], [Zn{(OPPh 2 )(OPPh 2 )N- O , O } 2 ] [34], [Zn{(SPPh 2 )(SPPh 2 )N- S , S } 2 ] [35], [Ga{(OPPh 2 )(OPPh 2 )N- O , O } 3 ] [36], [Ni{(Ph 2 P) 2 N- S -CHMePh- P , P }Cl 2 ] [37]. These complexes are abbreviated as Cu(O,O) 2 , Zn(O,O) 2 , Zn(S,S) 2 , Ga(O,O) 3 and Ni(P,P)Cl 2 , respectively.…”

Vinyl polymerization of norbornene catalyzed by 2‐Py‐amidine Ni(II) complex/methylaluminoxane systems

“…Nickel catalysts with less bulky diphosphinoamine ligands (Ph 2 PN(R)PPh 2 ) bearing N‐pendant donor groups (R) were found to oligomerize ethylene with activities of 10 5 g (mol Ni) −1 h −1 . Nickel catalysts bearing diphosphinoamine ligands (Ph 2 PN(R)PPh 2 , R = ―C 6 H 4 ‐ p ‐OMe, ―S―CHMePh) were found to polymerize norbornene with activities of 10 5 g (mol Ni) −1 h −1 . Cámpora's and Pringle's groups showed that, upon activation, the analogous four‐membered nickel complexes with small bite angle diphosphinomethane ligands display higher activity for ethylene polymerization and produce higher molecular weight products than those with wide bite angle diphosphines based on longer linkage backbones .…”