Studies of {[1](1,1')ferroceno[1](1,1')ruthenocenophane}-1-ylium hexafluorophosphate and related alpha-carbonium salts

The oxidation of [1](1,1')ferroceno[1](1,1')ruthenocenophane ([1.1]FcRc) and ferrocenylruthenocenylmethane (FcCH(2)Rc) with bromo- or chlorobis(eta(5)-cyclopentadienyl)ruthenocenium(1+) hexafluorophosphates gave the title compound, [Fe(C5H4CH2C5H4)(C5H4CH+C5H4)Ru]PF6- (1), as an alpha-carbonium salt and ferrocenylruthenocenylmethylium(+) hexafluorophosphate [FeCp(C5H4CH+C5H4)CpRu]PF6- (3), respectively. The crystal of 1 has been found to be triclinic, space group <P(1)over bar>, a = 10.572(9), b = 10.581(3), c = 9.680(5) Angstrom, alpha = 99.50(3)degrees, beta = 108.14(5)degrees, gamma = 88.30(5)degrees, Z = 2, and the final R = 0.082 and R(w) = 0.094. The distance between the Ru and Fe is 4.507(3) a, which is much shorter than the value of neutral [1.1]FcRc one (4.792(2) Angstrom). The two C5H4 rings in the Re moiety are tilted largely (the tilting angle is 10.74 degrees) due to a strong Ru ... C-alpha (alpha-metylium) interaction. The crystal of 3 has been found to be orthorhombic, space group P-bca, a = 17.062(5), b = 19.172(6), c = 12.580(7) Angstrom, Z = 8, and the final R = 0.067 and R(w) = 0.072. The tilting angle of the Re moiety is 7.98 degrees. The most interesting difference between 1 and 3 is found in the distance between the Ru and C-alpha atoms; i.e., the distance of 3 (2.43(2) Angstrom, closer to the Ru-C covalent bond) is significantly shorter than the value of 1 (2.51(1) Angstrom, somewhat longer to the covalent bond); therefore, the greater positive -CH+- charge can be stabilized by a delocalization of the charge over the [RuCp(C5H4CH)](+) fragment for 3. However, the -CH+- charge is spread out over [Fe(C5H4CHC5H4)(C5H4CH2C5H4)Ru](+) for 1. Temperature-dependent Fe-57-Mossbauer spectroscopy (areal intensity ratio of ferrocene and ferrocenium) supports above the conclusion.