High-nuclearity nickel(II) clusters: Ni13 complexes from the use of 1-hydroxybenzotriazole

The reaction of 1-hydroxybenzotriazole, btaOH, with nickel(II) acetate tetrahydrate, in the absence of an external base, has been investigated. The reaction of Ni(O2CMe)2 · 4H2O with one equivalent of btaOH in nPrOH leads to the the first structurally characterized tridecanuclear nickel(II) cluster and the biggest metal/btaOH or btaO− cluster discovered to date, [Ni13(OH)6(O2CMe)8(btaO)12(H2O)6(nPrOH)4] · 6.6H2O · 4(nPrOH) (1 · 6.6H2O · 4(nPrOH)). The centrosymmetric molecule contains the {Ni13(μ3-ΟΗ)6(μ3-ONNNR)12}8+ core (R– = C6H4–) and is characterized by competitive antiferromagnetic exchange interactions within its pentanuclear subunits containing the μ3-ΟΗ− bridges. The reaction of 1 with an excess of N3- ions in refluxing MeOH has led to the azido-bridged product [Ni13(N3)6(O2CMe)8(btaO)12(MeOH)10] (2), in which the spin frustration observed in 1 seems to disappear.

The 1:1 Ni(O2CMe)2 · 4H2O/1-hydroxybenzotriazole reaction system in propanol gives a tridecanuclear cluster which has the shown {Ni13(μ3-OH)6(μ3-ONNNR)12}8+ core; the compound is the biggest metal 1-hydroxybenzotriazole cluster discovered to date and the first Ni13 complex. The μ3-ΟΗ− groups can be replaced by end-on, triply bridging N3- ligands.Figure optionsDownload as PowerPoint slide