title: Influence of P-Bonded Bulky Substituents on Electronic Interactions in Ferrocenyl-Substituted Phospholes.
abstract: 2,5-Diferrocenyl-1-Ar-1H-phospholes 3 a-e (Ar=phenyl (a), ferrocenyl (b), mesityl (c), 2,4,6-triphenylphenyl (d), and 2,4,6-tri-tert-butylphenyl (e)) have been prepared by reactions of ArPH2 (1 a-e) with 1,4-diferrocenyl butadiyne. Compounds 3 b-e have been structurally characterized by single-crystal XRD analysis. Application of the sterically demanding 2,4,6-tri-tert-butylphenyl group led to an increased flattening of the pyramidal phosphorus environment. The ferrocenyl units could be oxidized separately, with redox separations of 265 (3 b), 295 (3 c), 340 (3 d), and 315 mV (3 e) in [NnBu4 ][B(C6 F5 )4]; these values indicate substantial thermodynamic stability of the mixed-valence radical cations. Monocationic [3 b](+)-[3 e](+) show intervalence charge-transfer absorptions between 4650 and 5050 cm(-1) of moderate intensity and half-height bandwidth. Compounds 3 c-e with bulky, electron-rich substituents reveal a significant increase in electronic interactions compared with less demanding groups in 3 a and 3 b.
authors.affiliation: Technische Universität Chemnitz, Faculty of Natural Sciences, Institute of Chemistry, Inorganic Chemistry, 09107 Chemnitz (Germany), Fax: (+49) 371-531-21219.
authors.forename: Dominique
authors.initials: D
authors.lastname: Miesel
authors.affiliation: Technische Universität Chemnitz, Faculty of Natural Sciences, Institute of Chemistry, Inorganic Chemistry, 09107 Chemnitz (Germany), Fax: (+49) 371-531-21219.
authors.forename: Alexander
authors.initials: A
authors.lastname: Hildebrandt
authors.affiliation: Technische Universität Chemnitz, Faculty of Natural Sciences, Institute of Chemistry, Inorganic Chemistry, 09107 Chemnitz (Germany), Fax: (+49) 371-531-21219.
authors.forename: Marcus
authors.initials: M
authors.lastname: Korb
authors.affiliation: School of Chemistry and Biochemistry, University of Western Australia, Crawley, Perth, WA 6009 (Australia).
authors.forename: Duncan A
authors.initials: DA
authors.lastname: Wild
authors.affiliation: School of Chemistry and Biochemistry, University of Western Australia, Crawley, Perth, WA 6009 (Australia).
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Low
authors.affiliation: Technische Universität Chemnitz, Faculty of Natural Sciences, Institute of Chemistry, Inorganic Chemistry, 09107 Chemnitz (Germany), Fax: (+49) 371-531-21219. heinrich.lang@chemie.tu-chemnitz.de.
authors.forename: Heinrich
authors.initials: H
authors.lastname: Lang
keywords: electrochemistry; electron transfer; heterocycles; phospholes; structure elucidation