Dinuclear copper(II) trispyrazolylborate derivatives with bridging pyrazolate anions

Two μ-pyrazolate dicopper derivatives, [Cu2(μ-pz)2(Tpx)2] [Tpx = Tp, tris(pyrazol-1-yl)borate or Tp∗, tris(3,5-dimethylpyrazol-1-yl)borate], prepared either by treating the trinuclear [Cu3(μ3-OH)(μ-pz)3(RCOO)2LxL′y] species (R = H, Me, Et, Pr; L, L′ = H2O, MeOH, EtOH, Hpz; Hpz = pyrazole) with an excess of M[Tpx] (M = Na, K) or by reaction of Cu(RCOO)2 with equimolar amounts of Hpz and M[Tpx], have been characterized by IR, magnetic susceptibility measurements and single crystal XRD structural determination.

Trispyrazolylborate (Tp) and tris(3,5-dimethyl)pyrazolylborate (Tp∗) partially break the trinuclear triangular core of the cluster [Cu3(μ3-OH)(μ-pz)3(MeCOO)2(Hpz)], generating dinuclear Cu(II) μ-pyrazolate compounds 2 and 3, having as capping κ3 ligands Tp and Tp∗, respectively. The structure of 3 is strongly influenced by the steric encumbrance of the methyl substituents, that keeps the two Cu ions in 3 farther with respect to 2.Figure optionsDownload as PowerPoint slide