2,6,10-Dodeca triene nickel complex

Cooligomerization (hetero-oligomerization) of olefins and acetylenes with butadiene in the presence of nickel complexes prevents the formation of butadiene trimers. During hetero-oligomerization chain and cyclic compounds may be formed see equations (13.87) and (13.88). Dodeca-2,6,10-triene-l,12-diylnickel reacts with allene to give various products. Reaction (13.89) is an example. 

The pure olefin complex, (cyclo-octa-1,3,5-triene)(cyclo-octa-l,5-diene) iron, CjHioFeCsHia, has been prepared in 13% yield by this route [39] the analogous Ru and Os complexes have been reported [39a]. Cyclo-dodeca-l,S,9-triene nickel may be prepared similarly using trialkyl-aluminiums as the reducing agents [40]. 

Some allyl complxes may be reduced to alkene and the metal. The complex dodeca-2, 6, 10-triene-l,12-diylnickel is reduced by hydrogen with the formation of nickel and dodecane. Many other metal allyl compounds react in a similar manner. 

The crystal structure of (T]3,Ti2.octa-2(E), 7-dien-l-yl)(triphenylphosphine)nickel(II) tetrafluoroborate has been reportedlOO. The reported X-ray crystal structure of dodeca-2( ),6( ),10(Z)-trien-l-yl)nickel(II) hexafluorophosphate exhibited almost planar T 3,Tl2,T 2-coordination of the C12 ligand around the central nickel atom. Detailed solution NMR studies of the complex have been reported 02 The X-ray crystal structure of (Tl. Tl. Tl -dodeca-2( ),6( ),10(Z)-trien-l-yl)nickel(II) tris(pentafluorophenyl)fluoroborate, [Ni(Ci2Hi9)]FB(C6F5)3, was determined OS and the compound shown to be an active catalyst for the 1,4-cM-polymerisation of butadiene. 

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