Syntheses and single crystal structures of chiral tetrahedral clusters containing osmium

New chiral tetrahedral clusters (μ3-S)OsCoMo(CO)8C5H4C(O)R(R=H 2, CH3 3, C6H4C(O)OCH3 4) were synthesized by the reaction of the precursor (μ3-S)OsCo2(CO)9 1 with the functionally substituted metal exchange reagents [Mo(CO)3(η5-C5H4)C(O)R]− (R=H, CH3, C6H4C(O)OCH3). Then clusters 2, 3 and 4 were treated with 2,4-dinitrophenylhydrazine to obtain clusters (μ3-S)OsCoMo(CO)8C5H4CNNHC6H3(NO2)2R (R=H 5, CH3 6, C6H4C(O)OCH3 7), respectively. All the clusters were characterized by Element Analysis, IR and 1H NMR. The structures of clusters 3 and 4 were established by X-ray single crystal diffraction. Interestingly, carbonyl group on the cyclopentadienyl ligand and cyclopentadienyl ring are not in the same plane, in cluster 3, torsion angle C27–C28–C29–O18 is −176.1(9), but in cluster 4, torsion angle C12–C13–C14–O9 is 167.5(17), which shows that carbonyl function group on the cyclopentadienyl ligand offsets the cyclopentadienyl ring more markedly than that in cluster 3. It showed that both conjugated effects and space hinder of phenyl ring in the cluster 4 are important factors to decide atoms positioning in three-dimensional structure of the clusters.