Synthesis and X-ray crystal structure of the 3,5-dimethylpyrazolato copper(I) trimer, [Cu(pz″)]3

A moderately high-yield, high temperature synthesis of the title compound is reported. Crystals of tris[(3,5-dimethylpyrazolato-N 1 ,N 2 )copper(I)] are triclinic, a = 12.360(4), b = 14.637(4), c = 12.358(4) Å, α = 105.29(2), β = 119.83(2), γ = 93.99(3)°, Z = 4 (trimers, two per asymmetric unit), space group [Formula: see text]. The structure was solved by heavy atom methods and was refined by full-matrix least-squares procedures to R = 0.034 and R w  = 0.038 for 3877 reflections with I ≥ 3σ(I). The structure consists of trimeric molecules with an unusually short average Cu—N distance of 1.852 Å. The central Cu 3 N 6 nine-membered rings are planar to within 0.07 Å. The trimer units are linked in pairs about centres of symmetry by weak [Formula: see text] interactions averaging 2.946 Å. Keywords: pyrazolato copper (I) timer, copper (I) pyrazolate.