Electron-Deficient Early−Late Heterobimetallic Sulfido Clusters. Unusual Reactivities of Ti<sub>2</sub>Ru<sub>2</sub>S<sub>4</sub> Cubane-Type Clusters with Four Cyclopentadienyl Coligands KabashimaShin-ichiro KuwataShigeki HidaiMasanobu 1999 Treatment of [Cp<sub>2</sub>Ti(SH)<sub>2</sub>] (<b>1</b>; Cp = η<sup>5</sup>-C<sub>5</sub>H<sub>5</sub>) with [(Cp*Ru)<sub>4</sub>(μ<sub>3</sub>-Cl)<sub>4</sub>] (<b>2</b>; Cp* = η<sup>5</sup>-C<sub>5</sub>Me<sub>5</sub>) in a Ti:Ru ratio of 1:1 afforded the hydrosulfido-bridged titanium−ruthenium heterobimetallic complex [Cp<sub>2</sub>Ti(μ<sub>2</sub>-SH)<sub>2</sub>RuClCp*] (<b>3</b>). Complex <b>3</b> reacted with an excess of triethylamine to give the early−late heterobimetallic cubane-type sulfido cluster [(CpTi)<sub>2</sub>(Cp*Ru)<sub>2</sub>(μ<sub>3</sub>-S)<sub>4</sub>] (<b>4</b>), with a loss of HCl and cyclopentadiene. An X-ray diffraction study and extended Hückel molecular orbital calculations for the 60e<sup>-</sup> cluster <b>4</b> demonstrated that <b>4</b> has four Ru→Ti dative bonds and a weak Ti−Ti interaction. The reaction of <b>4</b> with 3 equiv of [Cp<sub>2</sub>Fe][PF<sub>6</sub>] afforded the dicationic cubane-type cluster [(CpTi)<sub>2</sub>(Cp*Ru)<sub>2</sub>(μ<sub>3</sub>-S)<sub>4</sub>][PF<sub>6</sub>]<sub>2</sub> (<b>5</b>), which contains an additional Ru−Ru bond. In contrast, oxidation of <b>4</b> with an excess of HCl at room temperature resulted in the formation of the neutral dichloride cluster [(CpTiCl<sub>2</sub>)(CpTi)(Cp*Ru)<sub>2</sub>(μ<sub>3</sub>-S)<sub>4</sub>] (<b>6</b>). Clusters <b>5</b> and <b>6</b> were converted into each other by treatment with chloride or hexafluorophosphate anion. Furthermore, substitution of one of the cyclopentadienyl ligands in <b>6</b> by a chloride anion took place in boiling 1,2-dichloroethane to give the trichloride cluster [(TiCl<sub>3</sub>)(CpTi)(Cp*Ru)<sub>2</sub>(μ<sub>3</sub>-S)<sub>4</sub>] (<b>7</b>). The detailed structures of these oxidized cubane-type clusters <b>5</b>·2DMF, <b>6</b>·CH<sub>2</sub>Cl<sub>2</sub>, and <b>7</b>·CH<sub>2</sub>Cl<sub>2</sub> as well as the hydrosulfido-bridged dinuclear complex <b>3</b> have also been determined by X-ray crystallography. The Ti<sub>2</sub>Ru<sub>2</sub>S<sub>4</sub> cubane-type cores in <b>5</b>−<b>7</b> differ considerably in structure from each other, depending upon the ancillary ligands bound to the Ti atoms, although they have a Ru−Ru bond and two Ru→Ti dative bonds in common.