Herein, we report a rational synthetic access to dinuclear CuII complexes with radical monocationic guanidine ligands. The starting point was the first directed synthesis of a dinuclear CuII complex of the redox-active, neutral guanidino-functionalized aromatic (GFA) compound 1,2,4,5-tetrakis(tetramethylguanidino)benzene ( 1) as ligand by treatment of 1 with Cu(OAc)2. The neutral complex [ 1{Cu(OAc)2}2] was then oxidized with several oxidizing reagents. With I2 two-electron oxidation occurred, thus leading to green salts of the dication [ 1{Cu(OAc)2}2]2+. In contrast, with AgPF6 or AgSbF6 one-electron oxidation was observed to yield red salts of the monocation [ 1{Cu(OAc)2}2]+, which is a three-spin system with one unpaired electron at each copper atom and at the ligand unit. Superconducting quantum interference device (SQUID) magnetometric measurements confirm a quartet electronic ground state that arises from strong ferromagnetic copper-ligand coupling. Intense charge-transfer transitions in the visible region (576 and 536 nm) were observed in the electronic absorption spectra and assigned to strong ligand-ligand ( 1·+←OAc) charge-transfer (LLCT) excitations. These LLCT bands open up the possibility of photoinduced redox reactions with [ 1{Cu(OAc)2}2]+ driven by restoration of the aromatic system at the GFA ligand. [ABSTRACT FROM AUTHOR]