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Molecular Structures of Some syn -[1.1]Metallocenophanes, anti -Ferrocenium[1.1]ruthenocenophane, and Their NMR Spectroscopies

1998; Oxford University Press; Volume: 71; Issue: 9 Linguagem: Inglês

10.1246/bcsj.71.2127

1348-0634

Masanobu Watanabe, Masaru Satô, Akira Nagasawa, Izumi Motoyama, Toshio Takayama,

Metal complexes synthesis and properties

Abstract The structures of ferroceno[1.1]ruthenocenophane-1,13-dione (1a) and related compounds have been analyzed by X-ray diffraction. The crystal form of 1a is orthorhombic, space group Pbc21, a = 6.0660(3), b = 13.371(1), c = 19.420(2) Å, V = 1575.1(2) Å3, and the final R = 0.043 and Rw = 0.054. The air-oxidation of ferroceno[1.1]ruthenocenophane (2a) in xylene at 400 K gives ferroceno[1.1]ruthenocenophane-1-one (3a), implying the oxidation of the methylene group to a carbonyl group. The crystal form of 3a is orthorhombic, space group Pbn21, a = 7.6460(7), b = 10.708(1), c = 19.587(2) Å, V = 1603.7(3) Å3, and the final R = 0.052 and Rw = 0.051. The same oxidation is found for [1.1]ferrocenophane (2b) giving [1.1]ferrocenophane-1-one (3b). The crystal form of 3b is orthorhombic, space group Pbnm, a = 7.5460(9), b = 10.6560(6), c = 19.8290(7) Å, V = 1594.4(2) Å3, and the final R = 0.070 and Rw = 0.077. All the structural data of 1a, 3a, and 3b showed their syn conformation about two bridging methylene groups and rigid structures caused by the good planarity of C5H4COC5H4 and C5H4CH2C5H4 planes. These rigid structural features give remarkable variable temperature NMR (VT-NMR) spectra caused by the appropriate rate constant of syna⇔synb motion in solutions. The ΔG‡(Tc) values of the motion are estimated to be about 60 kJ mol−1, which is more than six times larger than those of 2a and 2b. The anti-form of ferrocenium[1.1]ruthenocenophane formulated as [FeIII(C5H4CH2C5H4)2RuII]PF6 (4) was prepared by the oxidation of the syn-form 2a in sulfuric acid containing NH4PF6. This is the first example of the oxidative occurrence of the conformational change from syn- to anti-form. The crystal form of 4 is triclinic, space group P1, a = 9.350(2), b = 10.777(3), c = 10.980(3) Å, α = 91.84(3)°, β = 96.66(2)°, γ = 111.12(2)°, V = 1021.8(5) Å3 and the final R = 0.044 and Rw = 0.048. The cation contains largely twisted C5H4CH2C5H4 plane (the twist angle, 34.1—38.5°) and largely tilted and rotated Cp-rings of the Ru(C5H4)2 moiety.