Metal-cyanomethyl complexes are the simplest examples of ɑ-cyanoalkyl ligands and are therefore a fundamental category of organometallic species. They can be formally viewed as deprotonated acetonitrile complexes, and they have been shown to react as nucleophiles in carbon-carbon bond-forming reactions to form nitrile compounds, but these uses are hampered by the difficulty in forming the active cyanoalkyl species through direct C-H bond cleavage. While the robustness of acetonitrile towards C-H activation hinders the use of this molecule as a substrate in catalytic applications, it is a great advantage in using acetonitrile as a solvent, as it allows many reactions to proceed using strong bases or other reactive species that would be unstable in more protic solvents such as water. Largely for this reason, acetonitrile is frequently the solvent of choice for equilibrium studies involving the reactions of transition metal hydrides, as the metal-hydride species and the reagents used to prepare them are often reactive towards other solvents.