Dichloro[1,3-bispropane]nickel a coordination complex with the formula NiCl₂(dppp) (where dppp = Ph₂PCH₂CH₂CH₂PPh₂). It is used as a catalyst in organic synthesis. The compound is an orange crystalline powder.

Structure and properties

The compound exhibits C_2v symmetry

Crystallographic point group

In crystallography, a crystallographic point group is a set of symmetry operations, like rotations or reflections, that leave a central point fixed while moving other directions and faces of the crystal to the positions of features of the same kind...

 with square planar geometry at the central nickel atom. The compound is soluble in non-polar organic solvents and is diamagnetic.

Preparation

NiCl₂(dppp) is prepared by combining equal molar portions of nickel(II) chloride

Nickel(II) chloride

Nickel chloride , is the chemical compound NiCl2. The anhydrous salt is yellow, but the more familiar hydrate NiCl2·6H2O is green. It is very rarely found in nature as mineral nickelbischofite. A dihydrate is also known. In general nickel chloride, in various forms, is the most important source of...

 hexahydrate with 1,3-bis(diphenylphosphino)propane

1,3-Bis(diphenylphosphino)propane

1,3-Bispropane is a diphosphine often found as a ligand in coordination chemistry.The diphosphine can be prepared by the reaction of lithium diphenylphosphide and 1,3-dichloropropane.The diphosphine is a precursor to the complex dichloronickel, which is prepared by combining equimolar portions of...

 in 2-propanol.

Ni(H₂O)₆Cl₂ + dppp → NiCl₂(dppp) + 6 H₂O

Reactions

It is used in Grignard reagent reactions involving cross-coupling of aryl halides, converting enol ethers, dithioacetals, and vinyl sulfides to olefins. NiCl₂(dppp) is used because the douple phosphate ligand minimizes the reduction reactions with labile β-hydrogens.

Cross-coupling reactions of R-X compounds with organometallic nucleophiles are catalyzed by transition metal complexes such as NiCl₂(dppp). The R group consists of aryl, vinyl, or allyl groups and the X group is a good leaving group. Cross-coupling reactions are effective at producing carbon-carbon bonds. Catalysts that have bidentate phosphine ligands serve as the best catalysts.

NiCl₂(dppp) serves as the catalyst by bonding the two cross-coupling components to the nickel. The cross-coupling proceeds by oxidative addition of the aryl, vinyl, or allyl halide to NiCl₂(dppp) forming an oxidative addition adduct, R₁-NiCl(dppp). The organometallic nucleophile, R₂-MgBr, reacts with R₁-NiCl(dppp) and is followed by the cross-coupling reaction producing the R₁-R₂ product.

The compound is a catalyst for Kumada coupling

Kumada coupling

A Kumada coupling or Kumada-Corriu coupling is a cross coupling reaction in organic chemistry between an alkyl or aryl Grignard reagent and an aryl or vinyl halocarbon catalysed by nickel or palladium. This reaction is relevant to organic synthesis because it gives access to styrene derivatives...

reactions involving alkyl, alkenyl, aryl, and heteroaryl Grignard reagents with aryl, heteroaryl, and alkenyl halides.