Highly Strained, Ring-Tilted [1]Ferrocenophanes Containing Group 16 Elements in the Bridge: Synthesis, Structures, and Ring-Opening Oligomerization and Polymerization of [1]Thia- and [1]Selenaferrocen
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- 作者：Ron Rulkens ; Derek P. Gates ; David Balaishis ; John K. Pudelski ; Douglas F. McIntosh ; Alan J. Lough ; and Ian Manners
- 刊名：Journal of the American Chemical Society
- 出版年：1997
- 出版时间：November 12, 1997
- 年：1997
- 卷：119
- 期：45
- 页码：10976 - 10986
- 全文大小：317K
- 年卷期：v.119,no.45(November 12, 1997)
- ISSN：1520-5126
文摘
The first chalcogen-bridged [1]ferrocenophanesFe(
-C5H3R)2E (6,E = S, R = H; 7, E = Se, R = H;12,E = S, R = Me) have been synthesized and characterized bothstructurally and spectroscopically. Synthesis ofsulfur- and selenium-bridged species 6 and 7 wasachieved by the reaction of dilithioferrocene·TMEDA(TMEDA= tetramethylethylenediamine) with bis(phenylsulfonyl) sulfideS(O2SPh)2 and seleniumdiethyldithiocarbamateSe(S2CNEt2)2,respectively, in 20-30% yields. Structural characterization ofboth 6 and 7 revealed highlystrainedstructures with tilt-angles between the cyclopentadienyl ligands of31.05(10)
and 26.4(2), respectively.Compounds6 and 7 are purple and red-purple, respectively;comparison of the structures of known [1]ferrocenophanes1 showedthat when the second period (from group 14-16) is traversed, there isa substantial increase in cyclopentadienylring-tilting in main group element bridged [1]ferrocenophanes,and the lowest energy UV/vis absorption peaks becomeincreasingly red-shifted. Extended Hückel MO calculationswere performed and, consistent with this observation,predicted a decrease in the HOMO-LUMO gap as the ring-tilt increases.Thermal ring-opening polymerization(ROP) of both 6 and 7 afforded the insolublepoly(ferrocenyl sulfide)[Fe(-C5H4)2S]n8 and poly(ferrocenyl selenide)[Fe(-C5H4)2Se]n9, respectively. Differential scanning calorimetrystudies of the ROP process provided estimatesof the strain energies of 6 and 7 which were ca.130(±20) and 110(±20) kJ mol-1,respectively. Anionic ROP of6 also yielded the insoluble poly(ferrocenyl sulfide)8. However, linear soluble dimeric and trimerictrimethylsilyl-capped oligo(ferrocenyl sulfides) 10b and 11bwere synthesized by the reaction of 6 withdilithioferrocene·TMEDAfollowed by the addition of Me3SiCl and werecharacterized spectroscopically, electrochemically, and, for11b, byX-ray diffraction, and provide useful models for the analogous highpolymer. The dimethylated sulfur-bridged species12 was prepared as a mixture of isomers from the reactionbetween dilithiodimethylferrocene·TMEDA andS(O2SPh)2, and X-ray structural characterization of a singleisomer 12a showed the presence of a large tilt-angleof31.46(8). Thermal and anionic ROP of the isomer mixture12 afforded the first soluble poly(ferrocenylsulfide)[Fe(-C5H3Me)2S]n13 which was characterized by 1H and13C NMR, elemental analysis, thermogravimetricanalysis,and gel permeation chromatography. Cyclic voltammetric studies of13 showed the presence of two reversibleoxidation waves with a redox coupling 
E = ca. 0.32 V,which is consistent with the presence of significantlystronger M···M interactions compared to those present in otherring-opened poly(ferrocenes) derived from[1]ferrocenophanes.
-C5H3R)2E (6,E = S, R = H; 7, E = Se, R = H;12,E = S, R = Me) have been synthesized and characterized bothstructurally and spectroscopically. Synthesis ofsulfur- and selenium-bridged species 6 and 7 wasachieved by the reaction of dilithioferrocene·TMEDA(TMEDA= tetramethylethylenediamine) with bis(phenylsulfonyl) sulfideS(O2SPh)2 and seleniumdiethyldithiocarbamateSe(S2CNEt2)2,respectively, in 20-30% yields. Structural characterization ofboth 6 and 7 revealed highlystrainedstructures with tilt-angles between the cyclopentadienyl ligands of31.05(10) and 26.4(2), respectively.Compounds6 and 7 are purple and red-purple, respectively;comparison of the structures of known [1]ferrocenophanes1 showedthat when the second period (from group 14-16) is traversed, there isa substantial increase in cyclopentadienylring-tilting in main group element bridged [1]ferrocenophanes,and the lowest energy UV/vis absorption peaks becomeincreasingly red-shifted. Extended Hückel MO calculationswere performed and, consistent with this observation,predicted a decrease in the HOMO-LUMO gap as the ring-tilt increases.Thermal ring-opening polymerization(ROP) of both 6 and 7 afforded the insolublepoly(ferrocenyl sulfide)[Fe(-C5H4)2S]n8 and poly(ferrocenyl selenide)[Fe(-C5H4)2Se]n9, respectively. Differential scanning calorimetrystudies of the ROP process provided estimatesof the strain energies of 6 and 7 which were ca.130(±20) and 110(±20) kJ mol-1,respectively. Anionic ROP of6 also yielded the insoluble poly(ferrocenyl sulfide)8. However, linear soluble dimeric and trimerictrimethylsilyl-capped oligo(ferrocenyl sulfides) 10b and 11bwere synthesized by the reaction of 6 withdilithioferrocene·TMEDAfollowed by the addition of Me3SiCl and werecharacterized spectroscopically, electrochemically, and, for11b, byX-ray diffraction, and provide useful models for the analogous highpolymer. The dimethylated sulfur-bridged species12 was prepared as a mixture of isomers from the reactionbetween dilithiodimethylferrocene·TMEDA andS(O2SPh)2, and X-ray structural characterization of a singleisomer 12a showed the presence of a large tilt-angleof31.46(8). Thermal and anionic ROP of the isomer mixture12 afforded the first soluble poly(ferrocenylsulfide)[Fe(-C5H3Me)2S]n13 which was characterized by 1H and13C NMR, elemental analysis, thermogravimetricanalysis,and gel permeation chromatography. Cyclic voltammetric studies of13 showed the presence of two reversibleoxidation waves with a redox coupling E = ca. 0.32 V,which is consistent with the presence of significantlystronger M···M interactions compared to those present in otherring-opened poly(ferrocenes) derived from[1]ferrocenophanes.