ИСТИНА

Although boron-containing transition metal clusters exhibiting ortho-cycloboronation of the phosphine or diphosphine ligands on a metal atom are long known in metallaborane and monocarbon metallacarborane chemistry, examples of related 12-vertex dicarbon metallacarboranes were reported only recently , and all known complexes of these series are paramagnetic RuIII species having a 17-electron shell. All these complexes are readily prepared either from 18-electron exo-nido- or closo-ruthenacarboranes via thermal reactions in the presence and in the absence of CCl4 (see scheme), and many of them demonstrate high efficiency as catalyst precursors for the atom transfer radical polymerization (ATRP) of methyl methacrylate and of some other vinyl monomers. All new paramagnetic closo-ruthenacarboranes futuring mono- and bis(ortho-cycloboronation) either one or both P-phenyl groups of the ruthenium-bound diphosphine ligands were characterized by X-ray diffraction and, in addition, by EPR spectroscopy. These electron-deficient (17-electron) closo-ruthenacarboranes hold considerable promise in a variety of ways for the development of ruthenacarborane chemistry. As an initial study on the reactivity of paramagnetic ortho-phenylenecycloboronated closo-ruthenacarboranes, we report here the synthesis and structural characterization of a short series of new ruthenium-carborane complexes with the dioxygen ligand at the metal vertex, viz., [3-(2-O2)-3,3,8-[Ph2P(CH2)nPPh-µ-(C6H4-ortho)]-1,2-Me2-closo-3,1,2-RuIIC2B9H8] (n = 3, 4), respectively.