Charge‐Transfer‐Verbindungen mit Metallkomplexen. I. Bis( o ‐phenylendiamido)‐Nickel‐Komplexe als Donatoren

Charge Transfer Compounds of Metal Complexes. I. Bis( o ‐phenylenediamido)‐Nickel Complexes as Donors The synthesis of monosubstituted bis( o ‐phenylenediamido)‐nickel complexes NiL 2 =Ni(C 6 H 3 (NH) 2 R) 2 where R = H, OCH 3 , Cl, sec ‐butyl, and of the disubstituted complex Ni(C 6 H 2 (NH) 2 (CH 3 ) 2 ) 2 is described. Substitution has a strong influence on the polarographically investigated reduction/oxidation behaviour of the complexes. Reaction of the nickel complexes with strong electron acceptors A (A = chloranil, tetracyanoethylene, 2,3‐dichloro‐5,6‐dicyano‐ p ‐benzoquinone, 7,7,8,8‐tetracyanoquinodimethane) yields solid compounds with a stoichiometric composition NiL 2 : A = 1:1. IR. And UV./VIS. Spectroscopic data indicate an ionic ground state of the solids. Electrical conductivities of solids are in the range 4,3·10 −3 ω −1 cm −1 to 5·10 −12 ω −1 cm −1 at 298 K with activation energies of 0.33 eV to 1.68 eV. In some cases solution equilibria in acetone or dichloromethane have also been investigated. The general scheme is:The tight ion pair NiL   2 + A − gives no ESR.‐signal. Low temperatures or addition of R 4 NClO 4 salts favour the formation of the ionic species.