SYNTHESIS, CHARACTERIZATION AND REACTIONS OF THE TETRAHEDRAL MCOFES CLUSTERS CONTAINING A FORMYLCYCLOPENTADIENYL LIGAND ETA(5)-CHOC5H4MCOFES(CO)(8) (M = MO, W) - THE SINGLE-CRYSTAL STRUCTURE OF ETA(5)-CHOC5H4WCOFES(CO)(8)

The tetrahedral formyl-substituted cyclopentadienyl clusters eta(5)-CH OC5H4MCoFeS(CO)(8) (1a, M = Mo, 1b, M = W) were successfully prepared by isolobal displacement reactions of monoanions eta(5)-CHOC5H4(CO)(3) M- with a tetrahedral cluster Co2FeS(CO)(9). The formyl substituents o f la and Ib could undergo interesting transformation reactions to give a series of cluster derivatives containing various functionally subst ituted cyclopentadienyl ligands. Clusters 1a and 1b reacted with NaBH4 or with MeMgI followed by hydrolysis to give, respectively, primary a lcohol clusters eta(5)-HOCH2C5H4MCoFeS(CO)(8) (2a, M = Mo, 2b, M = W) and secondary alcohol clusters eta(5)-HOCHMeC5H4MCoFeS(CO)(8) (3a, M = Mo, 3b, M = W), whereas those with semicarbazide or with 2,4-dinitrop henylhydrazine afforded semicarbazone clusters eta(5)-NH2C(O)NHNCHC5H4 MCoFeS(CO)(8) (4a, M = Mo; 4b, M = W) and phenylhydrazone clusters eta (5)-2,4-(NO2)(2)C6H3NHNCHC5H4MCoFeS(CO)(8) (5a, M = Mo, 5b, M = W), re spectively. Further treatment of 2a and 2b with Et3OBF4 produced singl e clusters eta(5)-C2H5OCH2C5H4MCoFeS(CO)(8) (6a, M = Mo, 6b, M = W) an d double clusters [MCoFeS(CO)(8)](2)[eta(5)-C5H4CH2OCH2C5H4-eta(5)] (7 a, M = Mo, 7b, M = W). All the new clusters have been characterized by elemental analysis and spectroscopic methods, as well as, for 1b, by X-ray diffraction analysis.