SYNTHESIS AND CRYSTAL STRUCTURES OF NOVEL NICKELAOXACYCLOBUTANES. H. Grls, M. Weidmann, E. Dinjus Max-Planck-Gesellschaft Arbeitsgruppe CO2-Chemie, Friedrich-Schiller-Universitt Jena, Lessingstrae 12, 07743 Jena, Germany, phone: +49/3641-636336, fax: +49/3641-636332,e-mail:goerls@xa.nlwl.uni jena.de

Nickelaoxocyclobutane complexes are postulated as intermediates in the formation of cyclic carbonates from epoxides, carbon dioxide and a nickel(II)-species.[1] The only proof up to now for the existence of nickelaoxacyclobutanes 2 was given by the reaction of atomic nickel and ethylene oxide in an argon matrix.[2]

For the preparation of complexes of type 2 we present a new and much more convenient method using bidentate nitrogen ligands (tmed, bipy) to stabilize the nickel(II)-center. The reaction of oxiranes 1 with Ni(cod)2 in the presence of excess tmed leads to the formation of 2 in high yields. If electron rich epoxides (propylene oxide, butylene oxide and ethers of 1,2-epoxypropanes) are used no reactions take place with Ni(cod)2 under these conditions. The complexes 2 have been characterized spectroscopically and by X-ray diffraction studies.

References:

[1] R.J. De Pasquale, J.Chem.Soc. Chem. Comm., (1973) 157

[2] E.S. Kline, R.H. Hauge, J.L. Margrave and Z.H. Kafafi, High Temp. Sci., 30 (1990) 69-82