A better synthesis of biruthenocene and molecular structures of [RuIICp(C5H4C5H4)CpRuIVNCC2H5](BF4)(B2F7)CH3NO2, [RuIICp(2,2′-bipyridine)(p-benzoquinone)]BF4 and related salts

An interesting dimerization occurred during the oxidation of ruthenocene with an excess of p-benzoquinone containing BF2. E2O (abbreviated p-Bq/BF3) in a mixed solution of benzene and hexane, which gave biruthenocenium(BF4)(2) (A) in 89% yield. Reduction of A with TiCl3 gave biruthenocene in a good yield (68% from ruthenocene), which is the most elegant preparation of biruthenocene. Recrystallization of A from CH3NO2 containing C2H5CN gave a mixed-valence salt 3 formulated as [(RuCp)-Cp-II(C5H4C5H4)(CpRuC2H5CN)-C-IV] (BF4)(B2F7)CH3NO2 in which C2H5 CN coordinated to the Ru-IV center. The crystal of 3 was found to be monoclinic, space group P2(1)/a, a = 9.8930(8), b = 15.445(3), c = 19.728(3) Angstrom, beta = 92.57(1)degrees, V = 3011.3(1) Angstrom(3), Z = 4, and the final R = 0.075 and R-w = 0.093. Recrystallization of A from CH3NO2 containing 2,2'-bipyridine and p-benzoquinone gave a yellow planar salt 4 formulated as [(RuCp)-Cp-II(2,2'-bipyridine)(p-benzoquinone)]BF4 in which the olefin moiety of p-benzoquinone coordinated to the Ru-IV center in eta(2)-form. Salt 4 was also synthesized by the reaction of bromoruthenocenium (BF4) with p-benzoquinone and 2,2'-bipyridine in CH3NO2. The crystal of 4 was found to be monoclinic, space group P2(1), a = 8.516(3), b = 9.934(4), c = 11.995(4) Angstrom, beta = 103.78(1)degrees V = 985.6(6) Angstrom(3), Z = 2, and the final R = 0.040 and R-w = 0.050. The same p-Bq/BF3 oxidation of osmocene gave an orange red salt 5 formulated as [(Cp2OsFBF3)-F-IV]BF4 in which one of the F- atom of the BF4- ion coordinated to the Os-IV center. The crystal of 5 was found to be monoclinic, space group P2(1)/c, a = 8.065(1), b = 12.048(1), c = 16.730(2) Angstrom, beta = 94.497(8)degrees, V = 1620.6(3) Angstrom(3), Z = 4, and the final R = 0.055 and R-w = 0.070.