''trans'',''trans'',''trans''-(1,5,9 Cyclododecatriene)nickel(0) a

organonickel compound Organonickel chemistry is a branch of organometallic chemistry that deals with organic compounds featuring nickel-carbon bonds. They are used as a catalyst, as a building block in organic chemistry and in chemical vapor deposition. Organonickel com ...

with the formula NiC₁₂H₁₈, better known as ''t''-Ni(cdt). It is a 16-electron

coordination complex A coordination complex consists of a central atom or ion, which is usually metallic and is called the ''coordination centre'', and a surrounding array of bound molecules or ions, that are in turn known as ''ligands'' or complexing agents. Many ...

featuring trigonal planar

nickel Nickel is a chemical element with symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel is a hard and ductile transition metal. Pure nickel is chemically reactive but large pieces are slow to ...

(0) bound to the three

alkene In organic chemistry, an alkene is a hydrocarbon containing a carbon–carbon double bond. Alkene is often used as synonym of olefin, that is, any hydrocarbon containing one or more double bonds.H. Stephen Stoker (2015): General, Organic, an ...

groups in the

cyclododecatriene Cyclododecatrienes are cyclic trienes with the formula C12H18. Four isomers are known for 1,5,9-cyclododecatriene. The ''trans'',''trans'',''cis''-isomer is a precursor in the production of nylon-12. : Production The ''trans'',''trans'',''cis'' ...

ligand In coordination chemistry, a ligand is an ion or molecule (functional group) that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves formal donation of one or more of the ligand's electr ...

X-ray structural analysis X-ray crystallography is the experimental science determining the atomic and molecular structure of a crystal, in which the crystalline structure causes a beam of incident X-rays to diffract into many specific directions. By measuring the angles ...

demonstrates that the three olefins adopt a propeller-like arrangement around the nickel atom center, making the structure chiral. This extremely air-sensitive deep red solid was the first discovered Ni(0)-olefin complex.

Preparation and properties

The complex is prepared by reduction of anhydrous nickel(II) acetylacetonate in ether in the presence of the triolefin: :Ni(acac)₂ + ''t''-cdt + 2 Et₂AlOEt → ''t''-Ni(cdt) + 2 acacAlOEt + 2 C₂H₅• σ-Donating ligands such as

carbon monoxide Carbon monoxide (chemical formula CO) is a colorless, poisonous, odorless, tasteless, flammable gas that is slightly less dense than air. Carbon monoxide consists of one carbon atom and one oxygen atom connected by a triple bond. It is the simple ...

, isonitriles,

phosphine Phosphine (IUPAC name: phosphane) is a colorless, flammable, highly toxic compound with the chemical formula , classed as a pnictogen hydride. Pure phosphine is odorless, but technical grade samples have a highly unpleasant odor like rotting ...

s, and

hydrides In chemistry, a hydride is formally the anion of hydrogen( H−). The term is applied loosely. At one extreme, all compounds containing covalently bound H atoms are called hydrides: water (H2O) is a hydride of oxygen, ammonia is a hydride of ...

can readily add onto ''t''-Ni(cdt) to furnish tetrahedral 18-electron nickel complexes. It has been demonstrated that this fourth coordination site can be leveraged to separate the ''t''-Ni(cdt)

enantiomer In chemistry, an enantiomer ( /ɪˈnænti.əmər, ɛ-, -oʊ-/ ''ih-NAN-tee-ə-mər''; from Ancient Greek ἐνάντιος ''(enántios)'' 'opposite', and μέρος ''(méros)'' 'part') – also called optical isomer, antipode, or optical ant ...

s with recrystallization of

diastereomeric In stereochemistry, diastereomers (sometimes called diastereoisomers) are a type of stereoisomer. Diastereomers are defined as non-mirror image, non-identical stereoisomers. Hence, they occur when two or more stereoisomers of a compound have di ...

18-electron ''t''-Ni(cdt)L* complexes (where L* = optically active dimethylmenthylphosphine ligand).

Applications

The all-''trans''-(cdt) ligand has been shown to be easily displaced with olefins such as ''trans''- cyclooctene,

ethylene Ethylene (IUPAC name: ethene) is a hydrocarbon which has the formula or . It is a colourless, flammable gas with a faint "sweet and musky" odour when pure. It is the simplest alkene (a hydrocarbon with carbon-carbon double bonds). Ethylene i ...

, all-''cis''-(cdt),

norbornene Norbornene or norbornylene or norcamphene is a highly strained bridged cyclic hydrocarbon. It is a white solid with a pungent sour odor. The molecule consists of a cyclohexene ring with a methylene bridge between carbons 1 and 4. The molecule carr ...

, to give the corresponding colorless 16-electron Ni(0)-olefin complexes with coplanar geometry. Ni(cod)₂ can also be easily prepared from Ni(cdt). Recently, it was demonstrated that ''t''-Ni(cdt) can be used to synthesize unique air-stable 16-electron Ni(0)–olefin complexes, such as Ni(^Fstb)₃ and Ni(^4-tBustb)₃ using (''E'')- stilbene ligands.

References

{{DEFAULTSORT:Cyclododecatriene)nickel(0), trans, trans, trans-(1, 5, 9- Organonickel compounds Cyclic compounds Alkene complexes