Synthesis, characterisation and structure of a strained ring-tilted bis(indenyl)iron complex

Electrochemistry and UV/visible spectroscopy of phosphino-substituted bis(η5-indenyl)iron(II) complexes

“…These bands are likely to be d-d transitions since the HOMO is largely metal-based [19,31] and the extinction coefficients are less than 1,000 L.mol -1 .cm -1 . It has been observed that for methyl substitution the UV/visible spectra vary by only 12 nm (416-426 nm and 548-560 nm) [17,20]. For mono-TMS-substitution on the C 5 ring, we found that the UV/visible absorption peaks change by 10-22 nm whereas for disubstitution, all of the UV/visible absorption peaks shift to longer wavelength by 40-62 nm [12][13][14].…”

“…Only one redox process was observed in each of the rac/meso mixtures. Like the other diindenyl ferrocenes that have been reported [17][18][19][20][21], the redox process is reversible. This is in stark contrast to that of dppf in CH 2 Cl 2 , however, for which irreversible processes are observed [8].…”

“…One must be careful, therefore, when making comparisons between these systems. Diindenyl ferrocenes typically exhibit two UV/visible absorption bands (with extinction coefficients of between 300 and 900 L.mol -1 .cm -1 ), one near 420 nm and the other near 555 nm [17,18,20]. These bands are likely to be d-d transitions since the HOMO is largely metal-based [19,31] and the extinction coefficients are less than 1,000 L.mol -1 .cm -1 .…”

“…This paper reports on those studies. Additionally, in comparison to the analogous dicyclopentadienyliron(II) complexes, diindenyliron(II) complexes have barely been investigated [17][18][19][20][21]. We have recently reported systematic studies of the electrochemistry and UV/visible spectroscopy of a variety of methyl-and TMS-substituted diindenyl ferrocenes: the methyl-substituted complexes were found to be well behaved with (i) an additive relationship between the number of methyl groups and their ring position on the oxidation potential of the ferrocene and (ii) only minor effects on the UV/visible spectra [17].…”

Synthesis, structures and rac/meso isomerization behaviour of bisplanar chiral bis(phosphino-η5-indenyl)iron(II) complexes

“…We recently reported the preparation of the diindenyl analogue of 1,1 0 -bis(diphenylphosphino)ferrocene (dppf), [(1-PPh 2 -g 5 -C 9 H 6 ) 2 Fe], and the characterization of its rac and meso isomers by X-ray crystallographic studies of their tetracarbonylmolybdenum complexes [3]. Non-hydrocarbon-functionalized diindenyl ferrocenes are very sparse, especially in comparison to the cyclopentadienyl system: there are only a few silyl [4], boryl [5] and amino [6] complexes known in addition to ansa-carboryl [7], ansa-dimethylsilyl [8] and ansaferrocenyl [9] complexes. A patent claiming 7-methoxy-1-(diphenylphosphino), 7-(ethoxycarbonyl)-1-(diphenylphosphino), 7-phenyl-1-(diphenylphosphino), and 1-(dicyclohexylphosphino) diindenyliron complexes has also appeared [2].…”