Oxo Sulfido Heteronuclear Titanium−Rhodium Clusters with an Incomplete Doubly-Fused Cubane Structure

The unusual early−late oxosulfido complex
[{CpTi}2(μ4-O)(μ3-S)4{Rh4(CO)6)}] (2) results from carbonylation, under atmospheric pressure, of a purple
solution obtained by mixing Cp2Ti(SH)2 with {Rh(μ-OMe)(cod)}2] (cod = 1,5-cyclooctadiene) and traces of
water, which is responsible for the formation of the oxo
ligand. Replacement reactions of only two of the carbonyl groups in 2 by P-donor ligands selectively gives the
complexes [{CpTi}2(μ4-O)(μ3-S)4{Rh4(CO)4(PR3)2}] (PR3
= PPh3, P(OMe)3, P(OPh)3)). These unusual oxosulfido
complexes show an incomplete double cubane-type structure formed by two cubane-like moieties “Rh2TiS2O”each with one empty vertexfused through a common
“Rh2O” face, with the oxide ligand displaying an unusual
tetracoordination.