Nickel with Duroquinone and Cyclic Olefins

Complexes of Nickel with Duroquinone and Cyclic Olefins 

It was found that if bis(duroquinone)-nickel is thermally decomposed in the presence of cyclooctatetraene, cyclooctatetraene-duroquinone-nickel, (XXII), is obtained (56). A more convenient synthesis was found shortly thereafter in a one-step reaction of duroquinone with nickel carbonyl in the presence of the polyolefin. Using the same procedure, analogous complexes with various other olefins were made, the properties of which are listed in 

and c= 14.17 A. The nickel is symmetrically bonded to the double bond centers of both the cyclooctadiene and the duroquinone molecules. The arrangement of the four double bonds is such that a tetra-hedrally coordinated nickel results. Similar structures may be anticipated for the remaining complexes of the type olefin-duroquinone-nickel. 

All complexes of this kind are quite polar and water soluble. The permanent dipole moments are caused by the fact that the olefinic ligands are predominantly donors and only weak acceptors so that the duroquinone molecule interacts with filled 3d orbitals of nickel even more strongly than in the case of bis(duroquinone)-nickel. Consequently, the quinone C=0 groups are more polarized than in the parent compound bis(duroquinone)-nickel (see Table I). The particularly high stability and polarity of the 

All the duroquinone-nickel complexes are diamagnetic. Attempts to prepare similar compounds with o-quinones have failed. It is also impossible to prepare bis(trimethylquinone)-nickel. Instead, the Ni(II) salt of tri-methylquinone is isolated (55). Evidently a slight increase in the electron affinity of the quinone -n system is sufficient to induce oxidation of nickel. 

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C. Complexes of Nickel with Duroquinone and Cyclic Olefins... 

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