Mo/Rh Carboxylate: Heterometallic Compound Built of Homometallic Paddlewheel Units

Mixed-metal molybdenum(II)/rhodium(II) tetra(trifluoroacetate) of the composition [(MoRh)(O2CCF3)4] has been obtained from the gas-phase reaction between volatile carboxylates, [Mo2(O2CCF3)4] and [Rh2(O2CCF3)4]. This is an interesting system for which a single-crystal X-ray investigation fails to provide an unambiguous evidence of whether the product consists of the initial homometallic or newly formed heterometallic paddlewheel units. In the solid-state structure both metal atoms occupy the same crystallographic position, while the M−M and M−O distances are averaged with respect to the parent homometallic compounds. Nevertheless, the results of mass-spectrometric and magnetic measurements clearly indicate that the title bimetallic carboxylate contains a statistical mixture of homometallic dimolybdenum and dirhodium units. The product can be considered as a result of cocrystallization of isomorphous paddlewheel molecules.