Access to Heteroleptic Fluorido-Cyanido Complexes with a Large Magnetic Anisotropy via Fluoride Abstraction.

Silicon-mediated fluoride abstraction is demonstrated as a means of generating the first fluorido-cyanido transition metal complexes. This new synthetic approach is exemplified by the synthesis and characterization of the heteroleptic complexes,trans-[(MF4)-F-IV(CN)(2)](2-)(M=Re, Os), obtained from their homoleptic [(MF6)-F-IV](2-)parents. As shown by combined high-field electron paramagnetic resonance spectroscopy and magnetization measurements, the partial substitution of fluoride by cyanide ligands leads to a marked increase in the magnetic anisotropy oftrans-[ReF4(CN)(2)](2-)as compared to [ReF6](2-), reflecting the severe departure from an ideal octahedral (O(h)point group) ligand field. This methodology paves the way toward the realization of new heteroleptic transition metal complexes that may be used as highly anisotropic building-blocks for the design of high-performance molecule-based magnetic materials.