Alkali‐Metal‐Templated Self‐Assembly of Nickel(II) [12‐MC‐3] Metallacoronates Based on Bis(pyrazol‐1‐yl)acetato Ligands

The syntheses and structures of four new bis(pyrazol‐1‐yl)acetate‐ or bis(3,5‐dimethylpyrazol‐1‐yl)acetate‐based bis‐ligand nickel(II) complexes [Ni(bdmpzmp) 2 ] ( 1 ), [Ni(bdmpzpen) 2 ] ( 2 ), [Ni(bdmpza) 2 ] ( 3 ), and [Ni(bpza) 2 ] ( 4 ) are described. The results of single crystal structure determinations reveal for all four complexes κ 3 ‐coordination of the scorpionate ligands. The sterically hindered bis(3,5‐di‐ tert ‐butyl‐pyrazol‐1‐yl)acetateto (bd t bpza) ligand allows the synthesis of the nickel(II) chlorido complex [Ni(bd t bpza)Cl] ( 5 ). Furthermore, controlled formation of a novel trinuclear linear complex [Ni(bdmpza) 2 {Ni(acac)(bdmpza)} 2 ] ( 6 ) [bdmpza = bis(3,5‐dimethylpyrazol‐1‐yl)acetate] by a self‐assembling reaction and alkali metal‐mediated template syntheses of [Na{Ni(acac)(bdmpza)} 3 ]NO 3 ( 7 ), [Na{Ni(acac)(bdmpza)} 3 ]I ( 8 ) and [Li{Ni(acac)(bdmpza)} 3 ]NO 3 ( 9 ) are reported. ESI MS allowed a detailed characterization in solution and is supported by X‐ray structure analysis. Compounds 7 , 8 and 9 exhibit [12‐MC‐3] metallacrown structures with a sixfold coordinated alkali metal ion in the center. The magnetic properties are studied by SQUID. Crystallographic data reveal broken symmetry in the solid state for all three [12‐MC‐3] metallacoronates 7 , 8 and 9 . The linear structure of [Ni(bdmpza) 2 {Ni(acac)(bdmpza)} 2 ] ( 6 ) (length ≈ 2 nm) obtained through synthesis without template, as well as the molecular structure of the [12‐MC‐3] metallacoronates 7 , 8 and 9 (∅ ≈ 1.3 nm) are at the nanoscale.