A new aqueous molybdenum cluster with a Mo3(μ3-CCH3)(μ3-O) trinuclear core

Reaction of Mo(CO)6 with propionic acid and propionic anhydride gives the expected μ3-propylidyne capped molybdenum cluster as well as the unanticipated μ3-ethylidyne capped molybdenum cation with bridging propionates, [Mo3(μ3-CR)(μ3-O)(μ-O2CCH2CH3)6(H2O)3]Br·4H2O; R = CH3 and CH2CH3. Due to the similarity in structure, both complexes crystallize together in the triclinic crystal system upon slow evaporation of NaBr solutions (T = 277 K). Herein, we report the synthesis, characterization, and crystallographic study of the carbon-capped clusters. To our knowledge, this study is the first to report a trinuclear molybdenum cation in which the μ3-alkylidyne ligand is not the same chain length as the carboxylic acid used in the synthesis.