Three novel copper hydrotris(3,5-diphenylpyrazolyl)borate (TpPh2) dithiocarbamate complexes, [TpPh2Cu(dtc)] (dtc = S2CNEt2 1, S2CNBz2 2 and S2CN(CH2)4 3) have been prepared in a simple one pot reaction by sequential addition of KTpPh2 and Na(dtc) to CuCl2[middle dot]2H2O. IR, UV-Vis and ESR spectroscopic studies suggest a mostly [small kappa]3 coordinated TpPh2 ligand, bidentate dithiocarbamate ligands and therefore, a five coordinate copper centre. Unusually, a [small kappa]3 to [small kappa]2 isomerisation of the TpPh2 ligand is found in solution in 3 and to a lesser extent in 1. The X-ray crystal structures reveal geometries intermediate between trigonal bipyramidal and square pyramidal depending on the steric bulk of the dithiocarbamate ligand and a long Cu-N bond resulting in an asymmetrically bound TpPh2 ligand. Electrochemical studies reveal quasi-reversible one-electron oxidation and reduction to Cu(I) with the reversibility and reduction potential strongly dependent on the dithiocarbamate. DFT