Expanding the scope of solvent-free synthesis: entrapment of thermally unstable species

The use of the acetone monoadduct, [Rh2(O2CCF3)4·(OCMe2)], instead of unligated dirhodium(II) tetrakis(trifluoroacetate) in sublimation–deposition reactions allowed us to study coordination of thermally sensitive 1,4-diiodo-1,3-butadiyne. A new mixed-ligand organometallic compound, [Rh2(O2CCF3)4·(OCMe2)]2·(C4I2), has been isolated in crystalline form and shown by X-ray diffraction study to have an η2(1,2):η2(3,4)-bridging mode of diyne. This has demonstrated the donor ability of the diiodobutadiyne that was previously known to act as a π-acceptor through the Lewis acidic iodine atoms. This work has expanded the temperature limits of the solvent-free synthesis strategy for potential study of thermally unstable species.