Designer Magnets Containing Cyanides and Nitriles

Magnets synthesized from molecules have contributed to the renaissance in the study of magnetic materials. Three-dimensional network solids exhibiting magnetic ordering have been made from several first-row metal ions and bridging unsaturated cyanide, tricyanomethanide, and/or dicyanamide ligands. These materials possess several different structural motifs, and the shorter the bridge, the stronger the interaction (i.e., -Ctriple bondN- > -Ntriple bondC-N- >> Ntriple bondC-N-Ctriple bondN- = Ntriple bondC-C-Ctriple bondN-). Cyanide additionally has the ability to discriminate between C- and N-bonding to form ordered heterobimetallic magnets, and the strong coupling can lead to ferro- or ferrimagnetic ordering substantially above room temperature. Tricoordination of tricyanomethanide results in spin-frustrated systems, which possess interpenetrating rutile-like networks. In contrast, single rutile-like frameworks are formed by mu(3)-bonded dicyanamide, which leads to ferromagnetics and weak ferromagnetics.