1. H. Egg, Mh. Chem.106, 1167 (1975)
2. W. Kl�tzer undR. Franzmiar, Mh. Chem.102, 724 (1971).
3. W. Kl�tzer, B. Schmidt undR. Franzmair, Mh. Chem.102, 635 (1971).
4. J. C. Jochims, Chem. Ber.98, 2128 (1965).
5. S. H�nig, H. Lehmann undG. Grimmer, Ann.579, 77 (1953).