The first 1,3,2-diazaphospha-[3]ferrocenophanes

1,1′-Diaminoferrocene 1 reacts with tert-butyl-(2a) and phenylphosphorus dichloride (2b) in the presence of triethylamine to afford the respective 1,3,2-diazaphospha-[3]ferrocenophanes 3a and 3b, of which 3a could be isolated in good yield and high purity. The phosphane 3a reacts with bis(trimethylsilyl)peroxide to give the oxide 5a, and with sulfur and selenium to the sulfide (6a) and the selenide (7a), respectively. The molecular structures of 3a and 7a, as determined by X-ray analysis, show that the tert-butyl group is in cis-position relative to the N–H bond vectors. NMR spectra prove that prominent structural features are retained in solution.