[Ru₃(CN)₃(CO)₉]^3-:Building Block for Multimetallic Cages

A cluster-ligand is disclosed in the form of [Ru-3(CN)(3)(CO)(9)](3-) ([1](3-)). Produced by simple reaction of [Ru-3(CO)(12)] with cyanide, [1](3-) serves as a precursor to a series of mu-CN cages. When treated with [Ru-3(CO)(12)], it readily forms the prism [Ru-6(mu-CN)(3)(CO)(18)](3-). With 1.5 equiv. of [Cu(MeCN)(4)](+) [1](3-) reacts to give the expanded prism {Cu-3[Ru-3(mu-CN)(3)(CO)(9)](2)}(3-), which features three two-coordinate Cu(I) centers. Sources of Ni2+ and Fe2+ bind two equivalents of [1](3-), giving the double cages {M[Ru-3(mu-CN)(3)(CO)(9)](2)}(4-) (M=Ni, Fe) wherein the central metal is octahedral. The 1 : 1 reaction using [Fe(H2O)(6)](2+) gave the interpenetrated super-tetrahedrane {Fe-4(mu(4)-O)[Ru-3(mu-CN)(3)(CO)(9)](4)}(4-).