Condensation of secondary 1,1′-diaminoferrocenes with phosphorus trihalides (PCl 3 or PBr 3 ) yielded either P-halo-1,3-diaza-2-phosphaferrocenophanes or 1,1′-diaminoferrocenediyl-bis(dichlorophosphines), respectively. The latter provide controlled access to both - and ferrocene frameworks. Thus, reductive coupling with magnesium gave diaza-diphosphaferrocenophane-annelated tetraphosphetanes, while a reaction with LiNMe 2 produced a P-chloro-diazaphosphaferrocenophane. Condensation of diaminoferrocenes and aminodichlorophosphines were mostly unselective, but afforded in one case a 3-aminoferrocenophane. All reaction products were characterised by spectroscopic and single-crystal XRD studies. DFT studies indicate that the product selectivity in the reactions studied depends on a combination of kinetic and thermodynamic effects, which correlate subtly with the steric bulk of the N-substituents. Cyclic voltammetry measurements revealed that the ferrocenophanes can undergo multiple oxidation events, the first of which may according to DFT studies be located in both the ferrocene and aminophosphine units. The quantum chemical studies provided also insight into stereochemical aspects like ring strain in the ferrocenophane units.
ASJC Scopus subject areas
- Inorganic Chemistry