NITRITO-COBALT(III)-COMPLEXES WITH ALPHA- DIOXIMES AND THE PROBLEMS OF THE COORDINATION OF THE NITRITE LIGAND

In co-ordination compounds there are various possibilities for the met al-nitrite bonding leading to the nitro (M-NO2)-isonitrite (M-ONO) iso merism. NO2 may function also as a bidentate ligand, forming both chel ates and polynuclear complexes containing various types of - NO2..., = NO2 bridges. The factors influencing the NO2 coordination are discuss ed. The synthesis and characterization of 28 new, different types of n itro-complexes with 1,2-cycloheptane dione dioxime (Heptox . H-2 - hep toxime): M[Co(Heptox . H)(2)(NO2)(2)], [Co(Diox . H-x)(2)L-2] [Co(Diox . H-xx)(2)(NO2)(2)], [Co(Heptox . H)(2) (NO2)L](o), co-ordination-, p osition-and structural izomers are described. (Diox . H-2(x), Diox . H -2(xx) aliphatic or alicyclic dioxime). The infrared spectra of some c obalt-and platinum complexes were recorded. By using the Central Force Field approximation, force constants were derived from the IR vibrati on frequencies. The correlation between the force constants and electr onic structure is discussed.