Preparation and reductive elimination of (. eta. sup 3 -allyl)(aryl)nickel(II) complexes: Unusually facile. eta. sup 3 -allyl-aryl coupling on nickel having an 18-electron configuration

Journal Article · Sat Dec 01 00:00:00 EST 1990 · Organometallics; (United States)

DOI:https://doi.org/10.1021/om00162a014· OSTI ID:5943772

Kurosawa, Hideo; Ohnishi, Hiroaki; Emoto, Mitsuhiro; Chatani, Naoto; Kawasaki, Yoshikane; Murai, Shinji; Ikeda, Isao ^[1]

---

1. Osaka Univ. (Japan)

The preparation and NMR spectral characterization of complexes of the type ({eta}{sup 3}-allyl)(aryl)(triphenylphosphine)nickel(II) (aryl = C{sub 6}H{sub 3}Cl{sub 2}-2,5, C{sub 6}F{sub 5}), 4, are described. Addition of PPh{sub 3} to a solution of 4 did not result in the formation of ({eta}{sup 1}-allyl)nickel intermediate as was deduced from {sup 1}H NMR measurements, in contrast to the ready conversion of ({eta}{sup 3}-allyl)palladium to ({eta}{sup 1}-allyl)palladium species. The (dichlorophenyl)nickel derivative underwent reductive elimination ca. 26 times as fast as the corresponding palladium complex. Addition of chelating diphosphine (Ph{sub 2}PCH{sub 2}CH{sub 2}PPh{sub 2}, (Z)-Ph{sub 2}PCH{double bond}CHPPh{sub 2}) to the solution of the above nickel complexes afforded stereochemically nonrigid 18-electron {eta}{sup 3}-allyl complexes, Ni({eta}{sup 3}-allyl)(aryl)(diphos), 5, which have been characterized by low-temperature {sup 1}H, {sup 13}C, and {sup 31}P NMR spectra for the C{sub 6}F{sub 5} analogues. This behavior is again different from that of the palladium analogue, which has an identical composition in which the 16-electron {eta}{sup 1}-allyl form is the ground-state structure. The kinetics of the reductive elimination of complexes 5 revealed that these undergo reductive elimination quite readily, with {Delta}H{sup {double dagger}} being ca. 60 kJ/mol lower than those values for the parent 16-electron counterparts 4. Also presented is evidence against the significant contribution of a short-lived 16-electron {eta}{sup 1}-allyl isomer of 5 to the enhanced reactivity with regard to the C-C coupling step in the diphosphine/allylnickel system.

• OSTI ID: 5943772
• Journal Information: Organometallics; (United States), Vol. 9:12; ISSN 0276-7333
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
NICKEL COMPLEXES
CHEMICAL PREPARATION
REDUCTION
ACTIVATION ENERGY
ALKYNES
ARGON COMPLEXES
CHELATING AGENTS
CHEMICAL REACTION KINETICS
CHEMICAL SHIFT
DIENES
FLUORINATED AROMATIC HYDROCARBONS
HOMOGENEOUS CATALYSIS
LOW TEMPERATURE
MOLECULAR STRUCTURE
NMR SPECTRA
PHOSPHINES
REACTION INTERMEDIATES
AROMATICS
CATALYSIS
CHEMICAL REACTIONS
COMPLEXES
ENERGY
HALOGENATED AROMATIC HYDROCARBONS
HYDROCARBONS
KINETICS
ORGANIC COMPOUNDS
ORGANIC FLUORINE COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
PHOSPHORUS COMPOUNDS
POLYENES
REACTION KINETICS
SPECTRA
SYNTHESIS
TRANSITION ELEMENT COMPLEXES
400201* - Chemical & Physicochemical Properties