Tripiperidinium pentaformato copper(II) – A unique homoleptic Cu(II) formate

[Display omitted] •Synthesis of discrete, mononuclear, homoleptic copper(II), [pipH]3[Cu(O2CH)5].•A unique CuO5 unit with a square-pyramidal Cu(II) in the solid state.•Single source precursor for low thermal self-reduction affording phase-pure Cu(0).•Decomposition studies reveal the in situ formation of an Cu(I) intermediary. The synthesis, structure and thermal decomposition behaviour of unique mononuclear, homoleptic [pipH]3[Cu(O2CH)5] (2) (pipH+ = piperidinium) is discussed in which the copper(II) ion is exclusively coordinated by five formate anions forming a distorted square-pyramidal coordination sphere. Thermogravimetric studies confirmed a comparatively low decomposition temperature (Tonset = 107 °C) affording solely elemental Cu. Based on TG-MS experiments a decomposition mechanism is presented. ______________________________________________________________________________