Display omitted •Mononuclear and binuclear Cu(II) complexes with Phen and B10Cl102− as counterion are isolated.•Electronic structure of triply-bridged complex is studied by EPR.•Non-covalent interactions are revealed in the triply-bridged Cu(II) complex by 35Cl NQR. The reaction between copper(II) acetate and Phen in the presence of B10Cl102− anion affords mononuclear copper(II) complex CuPhen2(CH3CO2)2B10Cl10·CuPhen(CH3CO2)2. Continuous heating of the latter in DMSO results in triply-bridged binuclear copper(II) complex Cu2Phen2(CH3CO2)2OH2B10Cl10 isolated from the reaction solution as a DMSO solvate hydrate Cu2Phen2(CH3CO2)2OH2B10Cl10·3DMSO·0.5H2O. Both complexes are studied by IR, 11B NMR, and X-ray diffraction; the binuclear complex is studied by 35Cl NQR and EPR spectroscopies as well as X-ray powder diffraction technique. Despite the short Cu−Cu distance revealed by X-ray diffraction analysis in the binuclear cationic complex (3.234 Å), no interactions between copper atoms are detected by EPR spectroscopy. According to 35Cl NQR studies, chlorine atoms bound with equatorial boron vertices of the boron cage participate in non-covalent interactions with H atoms of Phen molecules.