In this work we report on some aspects of the chemistry of the organic electron‐donor 1,2,4,5‐tetrakis(tetramethylguanidino)benzene (ttmgb). Reactions with electron acceptors and proton donors as well as late transition metals to give binuclear complexes (including a binuclear CuII complex with antiferromagnetic coupling through the bridging ttmgb ligand) are analysed. These studies shed some light on the electron‐donor/proton‐acceptor and coordination behaviour of this compound.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

Herein, we report a rational synthetic access to dinuclear Cu II complexes with radical monocationic guanidine ligands. The starting point was the first directed synthesis of a dinuclear Cu II 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 I 2 twoelectron oxidation occurred, thus leading to green salts of the dication [1{Cu(OAc) 2 } 2 ] 2+ . In contrast, with AgPF 6 or AgSbF 6 one-electron oxidation was observed to yield red salts of the monocation [1{Cu(OAc) 2 } 2 ] + , which is a three-spin system[a] Anorganisch-

In this work we follow the reaction of the strong electron donor 1,2,4,5‐tetrakis(tetramethylguanidino)benzene (ttmgb) with CuII nitrate. Three binuclear CuII complexes were isolated as products of this reaction. Depending on the reaction conditions, especially the molar ratio of the two reactants, the ttmgb ligand in these complexes is neutral, mono‐ or dicationic. All three complexes were structurally characterized. In addition to the experimental studies, quantum chemical calculations were carried out, which, in combination with experimental magnetic (SQUID) curves, especially shed light on the magnetic superexchange. The binuclear CuII complex of the ttmgb radical cation represents a three‐spin system. The SQUID magnetic data as well as the results of quantum chemical calculations indicate strong ferromagnetic copper‐ligand coupling.

Redox and coordination processes are coupled in the course of reactions of the organic electron donors 1,2,4,5‐tetrakis(tetramethylguanidino)benzene (1) and 1,2,4,5‐tetrakis(N,N′‐dimethyl‐N,N′‐ethyleneguanidino)benzene (2) with silver salts. Experiments with several different silver salts show that the product structure is significantly affected by the properties of the anion in these salts. Chain polymers are the products of reactions with AgPF6 or AgBF4, in which dicationic organic building blocks are connected by silver ions. Experiments with AgNO3 yielded either dinuclear complexes (with 1) or 2D networks (with 2). If the salt Ag[Al{OC(CF3)3}4], featuring a weakly coordinating anion, was used, simple silver‐free salts of the guanidine dication were obtained. The thermal stability, optical properties, and electrical conductivity were studied in detail for the product polymer {[(1)Ag](PF6)3}n. From the temperature dependence of the electric conductivity, this compound was found to be a semiconductor with a band gap of approximately 3 eV. The experiments were complemented by quantum chemical calculations at density‐functional‐theory level on the band structure of this and a related polymer. The electronic situation was further analyzed with the aid of molecular model complexes, which were either synthesized or calculated.

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