Dithiolene complexes as metallo-ligands: A crown-ether approach

A nickel dithiolene complex substituted with crown ether cyclic moieties incorporating four O atoms, abbreviated as [Ni(S2O4)2]1,0, is isolated in its radical anionic (as Na+ salt) and neutral forms. The Na+ cation is six-coordinated with short Na O distances (2.46-2.52 A ? ), involving two crown ether moieties of two different complexes. The oxidized neutral complex [Ni(S2O4)2]0 was also isolated and structurally characterized. In the absence of alkaline cations during the synthesis, a mixed salt associating [Ni(S2O4)2]1 with Ni2+ was isolated, and formulated as (Ni,H2O)[Ni(S2O4)2]2, with the Ni2+ cation weakly bonded to two crown ether moieties. The salt exhibits an unprecedented solid state association with extremely short S S intermolecular contacts [3.332(2) A ? ], leading to a pairing of the radical [Ni(S2O4)2] into antiferromagnetic uniform spin chains.