Synthesis and Structures of Strained, Neutral [d7] and Cationic [d6] Hydrocarbon-Bridged [n]Cobaltocenophanes (n = 2, 3)
摘要:
The first neutral and paramagnetic [n]cobaltocenophanes Co(eta(5)-C5H4)(2)(CH2)(2) (5) and Co(eta(5)-C5H4)(2)(CH2)(3) (6) with sterically undemanding hydrocarbon bridges were prepared by the reaction of CoCl2 with the corresponding ligand precursor (LiC5H4)(2)(CH2)(n) (n = 2 for 5; n = 3 for 6) in THF. In order to analyze the ring strain present, the molecular structures of 5 and 6 were determined using single-crystal X-ray diffraction. The neutral, paramagnetic 19-valence-electron [2]cobaltocenophane 5 is substantially distorted from metallocene-type geometry (tilt angle alpha: 27.1(4)degrees) and therefore highly strained, whereas [3]cobaltocenophane 6 is only moderately distorted (alpha: 12.0(11)degrees). Both 5 and 6 were readily oxidized with NH4Cl in the presence of atmospheric oxygen to form the corresponding cationic [n]cobaltocenophane salts [Co(eta(5)-C5H4)(2)(CH2)(n)(+)][A(-)] 7 and 8 (n = 2) and 9 (n = 3). Compound 7 (A = Cl) was isolated by means of extraction into CH2Cl2, whereas 8 and 9 were isolated by phase precipitation from aqueous solutions of NaPF6. The X-ray analysis for cationic, diamagnetic, 18-valence-electron [2]cobaltoceniumphane 7 revealed substantially less distortion from metallocene-type geometry (tilt-angle alpha: 21.4(2)degrees) compared to paramagnetic 19-valence-electron compound 5. In order to examine the electronic structures of 5, 6, 8, and 9, solution UV-vis spectra were recorded, and these reflected the increasing distortion as a result of the introduction of progressively shorter ansa-bridges. Cyclic voltammetric analysis of 8 and 9 in CH2Cl2 revealed that each cobaltoceniumphane exhibits a one-electron reduction, whereby redox potentials E degrees appeared to vary as a function of the tilt angle.
Main-Chain Heterobimetallic Block Copolymers: Synthesis and Self-Assembly of Polyferrocenylsilane-b-Poly(cobaltoceniumethylene)
作者:Joe B. Gilroy、Sanjib K. Patra、John M. Mitchels、Mitchell A. Winnik、Ian Manners
DOI:10.1002/anie.201008184
日期:2011.6.20
Main‐chain heterometallic blockcopolymers composed of iron‐ and cobalt‐rich blocks (see picture) were synthesized through consecutive photocontrolled ring‐opening polymerization (ROP) of sila[1]ferrocenophanes and dicarba[2]cobaltocenophanes followed by oxidation of the cobaltocene‐containing block. The redox properties and self‐assembly of the resulting blockcopolymers in solution were also studied
Ring-Opening Polymerization of 19-Electron [2]Cobaltocenophanes: A Route to High-Molecular-Weight, Water-Soluble Polycobaltocenium Polyelectrolytes
作者:Ulrich F. J. Mayer、Joe B. Gilroy、Dermot O’Hare、Ian Manners
DOI:10.1021/ja903513e
日期:2009.8.5
Water-soluble, high-molecular-weight polycobaltocenium polyelectrolytes have been prepared by ring-opening polymerization (ROP) techniques. Anionic polymerization of a strained 19-electron dicarba[2]cobaltocenophane followed by oxidation in the presence of ammonium chloride resulted in the formation of oligomers with up to nine repeat units. Thermal ROP of dicarba[2]cobaltocenophane followed by oxidation in the presence of ammonium nitrate resulted in the formation of high-molecular-weight polycobaltocenium nitrate, a redox-active cobalt-containing polyelectrolyte.