Coordination chemistry of a mixed donor bidentate ligand with nickel. A tetrameric enolate of sodium that binds a phosphine donor

Abstract

The preparation of a mixed donor ligand consisting of an enolate and neutral phosphine is described and its coordination chemistry with nickel reported. The phosphino ketones R,PCH,COPh (R = Cy or Pri) are prepared by the reaction of the corresponding secondary phosphines with bromoacetophenone to form the corresponding phosphonium salts [R,P(H)CH,COPh]+Br-(R = Cy or Pi); subsequent deprotonation leads to the neutral ketones. The enolates are formed by addition of NaN(SiMe,), to the neutral ketone. The crystal structure of the sodium enolate having isopropyl substituents at phospho~us displays a tetrameric structure in the solid state and there is an interaction of the phosphorus donor with the sodium anion: Na-P, 2.852(2) A. The preparation of a series of nickel complexes was achieved by addition of the sodium enolate to the appropriate Ni(I1) starting material. The structures of the nickel derivatives are reported. The catalytic behaviour of one of these complexes in the polymerization and oligomerization of ethylene is briefly described. ' Author to whom correspondence may be addressed. Telephone: (604)

Synthesis of New Late Transition Metal P,P-, P,N-, and P,O- Complexes Using Phosphonium Dimers as Convenient Ligand Precursors

“…This complex may be of interest for further investigations towards the synthesis of an ethylene oligomerization catalyst, as Fryzuk and co-workers have published a method of forming active olefin oligomerization catalysts from similar starting materials. 40 Also, a novel method of generating a diphosphine ligand containing a pendant aldehyde in a template method is presented using Pt(II) as the metal precursor. These ligands have potential for tethering metal complexes to heterogeneous materials making them more recyclable, or may be further transformed through functionalization of the alkene or aldehyde in the ligand backbone to generate more interesting ligands.…”

SHOP-type nickel complexes with alkyl substituents on phosphorus, synthesis and catalyticethylene oligomerization

“…There was no indication for the migration of a n-butyl substituent from the phosphorus atom to the metal centre. 54 The synthesis of b-keto phosphorus ylides from mixed alkyl/phenyl phosphonium salts could provide an access to SHOP-type nickel complexes having alkyl or mixed alkyl/phenyl substituents on the P atom of the P,O chelate. Such mixed salts were prepared by reaction of PPh 2 Cl with one equiv.…”

Facile synthesis of sterically demanding SHOP‐type nickel catalysts for ethylene polymerization

“…Typical synthesis of SHOP‐type catalysts involves the oxidative addition of a keto‐stabilized phosphorus ylide to Ni (0) in the presence PPh 3 (Scheme , I ) . Other synthetic methods based on phosphines were also developed (Scheme , II and III ) . However, the incorporation of the bulky aryl‐substituent on the phosphorous atom is very difficult to be obtained using these conventional synthetic methods.…”

“…[56] Other synthetic methods based on phosphines were also developed (Scheme 2, II and III). [65,67] However, the incorporation of the bulky aryl-substituent on the phosphorous atom is very difficult to be obtained using these conventional synthetic methods. To address this issue, herein, we report an alternative route for the synthesis of sterically demanding SHOP-type nickel catalysts for ethylene polymerization, and investigated the electronic effect of the ligand backbone structures on productivity and molecular weights.…”