1. Reed, H. B. W.: J. Chem. Soc. 1954, 1931
2. Wilke, G.: Angew. Chem. 75, 10 (1963); Angew. Chem. Internat. Edit. 2, 1 (1963)
3. A detailed information about the preparative work described in the theses of our group Buchholz, H., Fleck, W., Hey, H.-J., Meyer, V., Molin, M., Ploner, K.-J., Roloff, A., Schimpf, R., Scholz, K.-H., Selbeck, H., Thömel, F., Wiese, W. is given in Ref.4)
4. Jolly, P. W., Wilke, G.: The organic chemistry of nickel, Vol. 2 New York, San Francisco, London: Academic Press 1975
5. Heimbach, P.: Angew. Chem. 85, 1035 (1973); Angew. Chem. Internat. Edit. English 12, 975 (1973); for syntheses from the catalytically formed products see: J. Synth. Org. Chem. Japan 31, 299 (1973)