Synthesis of [2]ferrocenophanes containing trivalent diphosphine units

[3]Ferrocenophanes with the bisphosphanotetryl bridge: inorganic rings on the way to tetrylenes

“…The conformation of [3]ferrocenophane 8 is very similar to the ones found for halogenated derivatives 4, 6 and 7. Again the Cp-rings in 8 deviate slightly from coplanarity with an angle between the normal to the ring plane being 4.44 (8)°w hich fits into the trend with the halogenated compounds, while the angles at the silicon center vary slightly. Both hydrogen atoms adjacent to the silicon atom have been located and refined.…”

“…Phosphane 2 is readily prepared with lithium aluminium hydride from the corresponding chlorophosphane 1 which has been reported earlier in the literature (Scheme 1). 8,19 Lithiation with n-BuLi affords dilithiophosphanide 3 which was identified by multinuclear NMR spectroscopy. The salient feature of compound 3 is the symmetric bridging of the two lithium atoms between the phosphorus atoms in solution which is evident from the 31 P and 7 Li NMR spectra showing identical coupling from each lithium to both phosphorus nuclei ( Fig.…”

“…5,6 For bridging units with n = 2, 3 some ring tilts may still be present but the tendency for thermal ROP is significantly reduced. [7][8][9] Recently the unique setting in [3]ferrocenophanes has been used to prepare ferrocenylene bridged carbenes where for the corresponding cation direct interactions between iron and the cationic carbon atom have been suggested. 10,11 Owing to our own interest in the low-coordinate chemistry of group 14 elements we wondered whether it might be feasible to embed heavier tetrylenes into a bridging unit of a [3]ferrocenophane with flanking phosphanyl groups.…”

Strained Ferrocenophanes

“…89 Finally, diphospha [2]ferrocenophane 50 was isolated and structurally characterized (Figure 12), in addition to two similar species bearing either nBu of Ph substituents, which represent the first examples of [2]ferrocenophanes bearing two trivalent phosphorus atoms in the bridge. 114 Utilizing a general methodology similar to that employed in the synthesis of 49, species 50 was prepared via ring closure of a 1,1′-disubstituted ferrocene and formation of the E−E bridge, a synthetic methodology not commonly employed in strained [n]ferrocenophane synthesis. Although, to date, no reactivity pathways that could be attributed to the release of ring-strain have been reported, the potential application of diphospha [2]ferrocenophanes as diphosphine ligands has been assessed, through complexation of 50, and analogous species, with [W(CO) 5 species, 101,116 a mechanism of Fe−Cp bond weakening has been suggested.…”

Oligo(metallocene)s Containing Keto‐Bridged Phospholyl Rings

“…Oligo‐ and polymeric ferrocene‐based structures1–5 (Figure 1) have been the focus of much recent interest; inter alia, they are candidates for molecular motors6 and novel redox‐active materials,7–9 as catalysts for growing nanotubes,10 as physical switches,11 organometallic gratings12 and magnetic ceramics 2,13–15. The quite extended subset of phosphorus‐containing poly(metallocenephosphine)s ( 1 , G = PR)16 has been the subject of particular attention, because the presence of a phosphorus atom bridging the metallocene centres presents additional potential for preparing electroactive coordination compounds, polymers and related applications17,18 or for metal coordination that can tune the characteristics of the polymer 19. As far as we are aware, the phosphorus atoms in such metallocene polymers are invariably present as exocyclic substituents of classical metallocenes, as in 1 , so that no examples exist of conjugated oligo(phosphametallocene)s 2 , whose phosphorus atom is incorporated into the metallocene skeleton rather than the bridge 20.…”