Keywords: Electron donor ligands / Cobalt / Aluminum / N ligandsHerein we report on the synthesis and properties of a new electron donor featuring an aromatic system to which four guanidino groups are attached, namely, 1,4,5,8-tetrakis(tetramethylguanidino)naphthalene (ttmgn). The molecule is a double proton sponge with an asymmetric N-H···N bridge being formed in the protonated form. Oxidation is followed electrochemically, and two oxidation waves at E 1/2 (CH 3 CN) = -0.25 and +0.50 V vs. SCE are observed. Chemical oxidation with I 2 yields ttmgn(I 3 ) 2 , in which the I 3 units interact with the ttmgn 2+ cations through I···C contacts. Reaction with an excess amount of Br 2 leads to removal of four electrons from the aromatic system and formation of the salt (ttmgn)-Br 4 with a chair-type conformation of the C 10 core. The binuclear Al alkyl complex [(ttmgn)(AlMe 2 ) 2 ][BPh 4 ] 2 can be pre- [a] Anorganisch- Synthesis and CharacterisationThe synthesis of 3 turned out to be much more difficult than that of 2. Nevertheless, its preparation was achieved www.eurjic.org

Herein we report on the synthesis of the new strong N‐base and electron donor tdmegb [1,2,4,5‐tetrakis(N,N′‐dimethylethyleneguanidino)benzene]. Compared to the previously synthesized ttmgb [1,2,4,5‐tetrakis(tetramethylguanidino)benzene], this compound turned out to be a slightly better electron donor and a slightly weaker base. In experiments in which [AuCl(PPH3)] was dissolved in CH3CN together with tdmegb, we observed the formation of the first cyanomethyl complex of Au, namely [Au(CH2CN)(PPh3)] in good yield. This reaction does not take place for ttmgb. Moreover, in CH2Cl2 solutions containing the three components [AuCl(PPh3)], tdmegb and a nitrile (in large excess), only AuI reduction leading to a [Au11Cl3(PPh3)7] cluster is observed. Possible reaction mechanisms for this unusual reaction are discussed.

The reaction between BF(3)⋅OEt(2) and one of two guanidines, 1,8-bis(tetramethylguanidinyl)naphthalene (btmgn) and 1,2,4,5-tetrakis(tetramethylguanidinyl)naphthalene (ttmgn), yields the salts [(btmgn)(BF(2))]BF(4) and [(ttmgn)(BF(2))(2)](BF(4))(2). NMR spectroscopic data show that the boron atoms in the cation and anion exchange in the case of [(ttmgn)(BF(2))(2)](BF(4))(2), but not in the case of [(btmgn)(BF(2))]BF(4). The rate constant for this exchange was estimated to be 4 s(-1) at 80 °C for solutions in CH(3)CN. These salts were subsequently used for the reduction of dihalides Br(2) or I(2) to give polyhalide salts. We report the synthesis and first complete characterization (including structural analysis) of salts that contain pentabromide monoanions. In these salts, the Br(5)(-) anions interact to give dimeric units or polymeric chains. Our results are compared to previous quantum chemical calculations on the gas-phase structure of the Br(5)(-) anion. The possible pathways that lead to the polyhalides are evaluated. In the case of [(ttmgn)(BF(2))(2)](BF(4))(2), reduction is accompanied by ttmgn oxidation, whereas in the case of [(btmgn)(BF(2))]BF(4) reduction is initiated by aromatic substitution.

In this manuscript the reactivity of the two oxidation‐labile superbases 1,4,5,8‐tetrakis(N,N,N′,N′‐tetramethylguanidino)naphthalene and the newly synthesized 1,4,5,8‐tetrakis(N,N′‐dimethyl‐N,N′‐ethylene‐guanidino)naphthalene(tdmegn) are discussed and compared with that of related organic electron donors. The work includes oxidation with inorganic and organic oxidation reagents, as well as the preparation and characterization of dinuclear CoII, NiII and CuI complexes. Magnetic coupling in the dinuclear CoII and NiII complexes is studied on the basis of SQUID measurements. Finally, the results of experiments on the oxidation of the dinuclear CuI complexes are presented.

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