Vinyl-Functionalized Silanes and Disiloxanes with Electronically Communicated Ferrocenyl Units

• Published in: Organometallics Vol. 29; no. 12; pp. 2796 - 2807
• Main Authors: Bruña, Sonia, González-Vadillo, Ana M, Nieto, Daniel, Pastor, César, Cuadrado, Isabel
• Format: Journal Article
• Language: English
• Published: WASHINGTON American Chemical Society 28.06.2010; Amer Chemical Soc
• Subjects: Chemistry; Chemistry, Inorganic & Nuclear; Chemistry, Organic; Physical Sciences; Science & Technology; ORGANOMETALLIC DENDRIMERS; SUPPORTING ELECTROLYTE; N-BU; DELTA-E-1/2 VALUES; SILICON; STRUCTURAL-CHARACTERIZATION; IMPROVED ELECTROCHEMISTRY; POLY(FERROCENYLSILANE) HIGH POLYMERS; TRANSITION-METAL CENTERS; CYCLIC SILOXANES
• ISSN: 0276-7333; 1520-6041
• DOI: 10.1021/om1002733

A new series of vinyl-functionalized polyferrocenyl organosilicon compounds, including triferrocenylvinylsilane, (CH2CH)Si(Fc)3 (7) (Fc = (η5-C5H4)Fe(η5-C5H5)), 1,3-divinyl-1,1,3,3-tetraferrocenyldisiloxane, [(CH2CH)(Fc)2Si]2O (8), and 1,3-divinyl-1,3-dimethyl-1,3-diferrocenyldisiloxane, [(CH2CH)(Fc)MeSi]2O (9), have been synthesized via the low-temperature salt metathesis reaction of monolithioferrocene and the chlorosilanes (CH2CH)SiCl3 and [(CH2CH)(Cl)MeSi]2O. Compounds 7−9 were characterized by elemental analysis, multinuclear (1H, 13C, 29Si) NMR spectroscopy, and MALDI-TOF mass spectrometry. The molecular structures of the vinyl-functionalized silane 7 and divinyldisiloxanes 8 and 9 in the solid state have been determined by single-crystal X-ray analysis. Whereas tetraferrocenyl compound 8 possesses a linear disiloxane skeleton (Si−O−Si bond angle of 180.0(2)°), biferrocenyl 9 shows a bent arrangement of the disiloxane linkage (Si−O−Si angle of 143.2(2)°). The oxidation electrochemical behavior of polyferrocenyl molecules 7−9 has been examined by cyclic voltammetry and square wave voltammetry in dichloromethane solution, using hexafluorophosfate, [PF6]−, and tetrakis(pentafluorophenyl)borate, [B(C6F5)4]−, as supporting electrolyte anions of different coordinating ability. Compound 7 can be reversibly oxidized in three consecutive steps to the trication 7 3+ . Divinyldisiloxanes 8 and 9 are reversibly oxidized in four and two one-electron-transfer steps, respectively, which suggests significant electronic interaction among the ferrocenyl redox centers linked by the short three-atom Si−O−Si bridge.