Isomeric diphosphines of a heteroannularly bridged ferrocene: Preparation, chromatographic separation and structure elucidation

Article abstract of DOI:10.1016/0022-328X(95)05849-K

Twofold lithiation of the heteroannularly bridged aminophosphine 5 yielded a mixture of five isomeric aminodiphosphines 7a-7d and 11, which were separated by adsorption chromatography. Their substitution pattern was elucidated by X-ray structure analyses and chemical correlation. Corresponding diphosphines 10a-10d were derived with moderate yields via acetates 8a-8d. A search for stable conformers of 7a-7d and 11 was conducted using empirical force field calculations. Calculated minimum-energy geometries were compared with crystal structures of 7a, 7c and 7d.