Toshiro Takao

Synthesis and reactivity of dinuclear µ-silyl complexes of ruthenium having three-centre two-electron Ru–H–Si interactions

Reaction of [(C5Me5)Ru(µ-H)4Ru(C5Me5)] with R2SiH2 yields the dinuclear µ-silyl complexes [{(C5Me5)Ru(µ-η2-HSiR2)}2(µ-H)(H)]2a, R = Et; 2b, R = Ph, having three-centre two-electron interactions, and pyrolysis of 2b in refluxing toluene affords a dinuclear µ-silylene (silanediyl) complex [(C5Me5)Ru(µ-SiPh2)2(µ-H)2Ru(C5Me5)]3; the molecular structures of 2a and 3 have been determined by X-ray diffraction.

A Triruthenium Complex Capped by a Triply Bridging Oxoboryl Ligand

Since Mond et al. discovered [Ni(CO)4] in 1890, [1] the carbonyl ligand has been widely used as a supporting ligand or substrate in organometallic chemistry. Besides common terminal coordination, it is well-known that the carbonyl group can bridge multiple metal nuclei: m, m3, and m4 coordination modes have been recognized. For this reason, the CO ligand has a unique status, particularly in cluster chemistry. Many complexes containing isoelectronic NO ligands have also been prepared, and it has been demonstrated that NO ligands can adopt various coordination modes similar to those observed for CO. In contrast, although the properties of BO , another isoelectronic alternative to CO, have so far attracted considerable attention, a transition-metal complex containing a BO ligand was not been prepared until recently, probably as a result of the instability of free monomeric BO , in contrast to CO and NO. In 2010, Braunschweig et al. succeeded in the synthesis of the first platinum complex with a terminal oxoboryl ligand through the elimination of Me3SiBr from a siloxyboryl ligand. Not only did they elucidate the structural and spectroscopic properties of the BO ligand, but also its reactivity, and they demonstrated the Lewis basic nature of the BO ligand by the formation of a Lewis acid–base adduct with B(C6F5)3. [6] They also showed that the abstraction of the bromide ligand from trans-[(Cy3P)2BrPt(B O)] (Cy = cyclohexyl) resulted in cyclodimerization, which led to the formation of a four-membered B2O2 skeleton. [7] The formation of the B2O2 linkage is most likely due to the highly polarized nature of the B O bond. In contrast, CO ligands tend to dimerize by the formation of a m-CO ligand. Although bridging coordination was elucidated for the isoelectronic BF ligand by Vidovic and Aldridge, it has never been reported for the BO ligand, except in the case of a hypothetical dicobalt complex, [Co2(CO)6(m-CO)(m-BO)2], by density functional theory (DFT) calculations. Herein, we report the first synthesis and the properties of a triruthenium cluster capped by a m3-BO ligand. We previously studied the reactivity of a triruthenium complex capped by a m3-BH ligand in terms of C S bond scission and B C bond formation on the Ru3 plane. Recently, we showed the preferential formation of the triruthenium complex 2a, which contains a m3-h -BC2 ring, upon the irradiation of the alkyne complex 1 with visible light (Scheme 1). In contrast to irradiation with visible light, UV