Mixed-valence ferrocene systems temperature dependence in the mössbauer spectra of [Fe(II)Fe(III) [1.1] ferrocenophanes

✍ Scribed by William H. Morrison Jr.; David N. Hendrickson

• Publisher: Elsevier Science
• Year: 1973
• Tongue: English
• Weight: 419 KB
• Volume: 22
• Category: Article
• ISSN: 0009-2614
• DOI: 10.1016/0009-2614(73)80548-2

✦ Synopsis

Fe hlijssbauer spectra (300 and 4.2"Kl h:lve been determined I"OI dioxidized [Fc(lII)Fe(IIl)] b~&rrocenylent'; rt large quadrupole splitting (2.S9 mm/see at 300°K) was interpreted in tern-s of cxtensivc dclocdlization of e~c ekerrons resultant from an Fe-Fe bonciing inrcraction. Mijssbnuer and electronic abwrption spectra have alsa b&t drtcrmined L'OI two mono-osidized [ 1.11 ferroccnophancs. Tcmpcrature depcndcncc is noted in the [ Fe(II)Fe(III) 1 fcrrocenophanc ~fissbauer spectra and is Mltatively associated with a phase rransirion whcrcin rlic Fc-Fe disrnncc is changed to permit ecarcr Fc-Fe exchange interaction. Mono-oxidation of biferroccne gives the mixedvalence [Fe(lI)Fe(III)] compound (I) [l]. The 57Fe M6ssbauer spectrum [2,3] of this compound shows two quadrupole-sp6t

doublets and as such the ther-3.98 .%, whereas, the Fe-Fe distance in compound (I) is not known. In fact. the relative conformation of the two ferrocenyl moieties has not been esr:~blished. Some evidence for the presence of electron ex-ma1 rate of intervalence transfer is less than = IO7 set-l.

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