1. Gagliardi, E., Popitsch, A., Mh. Chem.103, 1337, (1972).
2. Popitsch, A., to be published.
3. We are obliged to the authorities of the ETH-Zürich for giving us the opportunity to use the diffractometer. Our special thanks are due to Prof.J. D. Dunitz and Mr.P. Seiler.
4. All calculations were carried out with the XRAY computer program system (J. M. Stewart, The XRAY system-version of 1976. Tech. Rep. TR-466. Computer Science Center, Univ. of Maryland, College Park, Md., USA).
5. Popitsch, A., Nachbaur, E., Neißl, W., Fritzer, H. P., Mh. Chem.,111, 1321 (1980);Neißl, W., Fritzer, H. P., Proc. XXI. Cell. Spectr. Inter., Ref. No. 110310, Cambridge, England (1979).