SYNTHESIS, STRUCTURES, AND PROPERTIES OF STRAINED, SILICON-BRIDGED [1]FERROCENOPHANES WITH METHYLATED CYCLOPENTADIENYL RINGS

Pudelski, J; Foucher, D; Honeyman, C; Lough, A; Manners, I; Barlow, S; Ohare, D

Journal article

SYNTHESIS, STRUCTURES, AND PROPERTIES OF STRAINED, SILICON-BRIDGED [1]FERROCENOPHANES WITH METHYLATED CYCLOPENTADIENYL RINGS

Abstract:: A series of strained, silicon-bridged [1]ferrocenophanes with methylated cyclopentadienyl rings, which are prospective monomeric precursors of poly(ferrocenylsilanes) via ring-opening polymerization, has been synthesized and characterized. The dimethylated silicon-bridged [1]ferrocenophanes Fe(η-C5H3Me)2SiMe2 (4) were prepared as a mixture of isomers via the reaction of Fe(η-C5H3MeLi)2·TMEDA (TMEDA = tetramethylethylenediamine) with Me2-SiCl2. The 3,3′-syn isomer 4a was cleanly isolated via low-temperature crystallization. The tetramethylated silicon-bridged [1]ferrocenophane Fe(η-C5Me4)(η-C5H4)SiMe 2 (6) and the octamethylated silicon-bridged [1]ferrocenophane Fe(η-C5Me4)2SiMe2 (8) were prepared via the reaction of FeCl2 with Li2[(C5Me4)(C5H 4)SiMe2] and Li2[(C5Me4)2SiMe2], respectively. X-ray diffraction studies of 4a and 8 revealed that these molecules possess highly strained ring-tilted structures. Comparison with the previously determined structure of Fe(η-C5H4)2-SiMe2 (1) revealed that, with increasing ring methylation, the tilt angle between the planes of the cyclopentadienyl ligands decreases significantly (1, 20.8(5)°; 4a, 18.6(3)°; 8, 16.1(3)°), the angle between the cyclopentadienyl ligand and the ipso cyclopentadienyl carbon-silicon bond increases (1, 37.0(6)°; 4a, 39.1(2)°; 8, 40.3(2)°), and the Fe-Si distance decreases (1, 2.690(3) Å; 4a, 2.6767(8) Å; 8, 2.652(1) Å). Cyclic voltammetric analysis of 1, 4a, 6, and 8 in CH2Cl2 revealed that each ferrocenophane exhibits a reversible, one-electron oxidation. Analysis of 1 and 8 by 57Fe Mössbauer spectroscopy in conjunction with the crystallographically determined trend in Fe-Si distances provided evidence for the presence of a weak dative Fe-Si interaction which is more substantial in the latter species than the former. Crystals of 4a (C14H18FeSi) are orthohombic, space group Pbca, with a = 14.775(2) Å, b = 10.655(2) Å c = 16.882(2) Å, V = 2657.7(7) Å3, and Z = 8. Crystals of 8 (C20H30FeSi) are monoclinic, space group C2/c, with a = 15.687(3) Å, b = 9.194(1) Å, c = 26.612(5) Å, β = 98.65(2)°, V = 3653(6) Å3, and Z = 8. © 1995 American Chemical Society.

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APA Style

Pudelski, J., Foucher, D., Honeyman, C., Lough, A., Manners, I., Barlow, S., & Ohare, D. (1995). SYNTHESIS, STRUCTURES, AND PROPERTIES OF STRAINED, SILICON-BRIDGED [1]FERROCENOPHANES WITH METHYLATED CYCLOPENTADIENYL RINGS. ORGANOMETALLICS, 14(5), 2470–2479.

MLA Style

Pudelski, J., et al. “SYNTHESIS, STRUCTURES, AND PROPERTIES OF STRAINED, SILICON-BRIDGED [1]FERROCENOPHANES WITH METHYLATED CYCLOPENTADIENYL RINGS.” ORGANOMETALLICS, vol. 14, no. 5, 1995, pp. 2470–79.

Chicago Style

Pudelski, J, D Foucher, C Honeyman, A Lough, I Manners, S Barlow, and D Ohare. 1995. “SYNTHESIS, STRUCTURES, AND PROPERTIES OF STRAINED, SILICON-BRIDGED [1]FERROCENOPHANES WITH METHYLATED CYCLOPENTADIENYL RINGS.” ORGANOMETALLICS 14 (5): 2470–79.
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