A suite of paddle-wheel shaped [Cu-2(PymPPh(2))(3)(L-an)(n)](PF6)(2) complexes showing efficient thermally activated delayed fluorescence (TADF) has been synthesized. In these complexes, Cu(I) ions are P,N-bridged by three diphenyl(2-pyrimidyl)phosphine (PymPPh(2), L) ligands in a "head-to-tail" fashion, and one or both metals are also capped by the ancillary ligand (L-an = MeOH, Me2CO, MeCN, PhCN). At ambient temperature, the solid complexes emit TADF with the quantum yield of up to 85% and the lifetimes of from 9.6 to 27 mu s. The ancillary ligands, whose orbitals negligibly contribute to the radiative (1)(M + L + L-an)LCT state, remarkably adjust emission energies and Delta E(S-1-T-1) energy splitting magnitudes of the emitters obtained. Thus, depending on structure and/or number of the L-an molecules, the emission maxima vary from 500 to 563 nm, and the Delta E(S-1-T-1) gaps range 550-1100 cm(-1). Such tunable TADF characteristics coupled with the excellent solubility and air-stability make the complexes presented to be promising TADF materials.