Tetracyanoquinodimethanido Derivatives of (Terpyridine)‐ and (Phenanthroline)metal Complexes − Structural and Magnetic Studies of Radical‐Ion Salts

Several derivatives of formulae [M(terpy) 2 ](TCNQ) 2 or [M(terpy) 2 ](TCNQ) 3 (M = Ni, Cu, Zn; terpy = 2,2′:6′,2"‐terpyridine; TCNQ= 7,7,8,8‐tetracyanoquinodimethane) and [M(phen) 3 ](TCNQ) 2 or [M(phen) 3 ](TCNQ) 4 (M = Fe, Ni; phen = 1,10‐phenanthroline) have been obtained. The crystal structures of [M(terpy) 2 ](TCNQ) 2 (M = Ni, Cu) show that the metal is surrounded by the terpyridine nitrogen atoms in a closed octahedral environment and the TCNQ anions are dimerised by π overlap. The cationic [M(terpy) 2 ] 2+ and the anionic [TCNQ] 2 2− groups alternate in the crystal. For the derivatives with three TCNQ groups, the existence of a stack of trimeric [TCNQ] 3 2− ions having electronic delocalisation is proposed. The compound [Fe(phen) 3 ](TCNQ) 2 , which shows a strong interaction between TCNQ anions, led to the formation of a σ bond in the diamagnetic species [TCNQ−TCNQ], while the nickel analogue is expected to have a localised structure formed by alternation of cationic metal complexes and dimeric [TCNQ] 2 2− anions similar to those observed in the analogous terpy derivatives. The derivatives having four TCNQ groups also show electronic delocalisation and a 1D stack based on the magnetic data is proposed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)