Cobalt nitrito ligands

Photochemistry of cis-[Co(en)2(N02)2] in neat acetonitrile differs from that in water. In aqueous solution excitation of the complex ion in the ligand-to-metal charge transfer band gives the cobalt(II) ion and the nitrito linkage isomer. In acetonitrile, an intermediate cobalt(II) complex coordinated to NO2 is produced. As previous studies have shown, the solvent employed has a marked effect on the reactivity pattern of excited states. The viscosity dependence of the photoaquation of [Co(CN)j " and a variety of Cr(III) complexes has been studied using glycerol-water mixtures. " Cage effects are not important in the photosubstitution of CN in the systems studied. 

Ligand Replacement Unidentate by Unidentate.—dissociative mechanism is proposed for the replacement of nitrito- or of thiocyanato-ligands in trans-[Co(dmgH)2(N02)2] and in rm/w-[Co(dmgH)2(NCS)2] respectively by thiourea. Thiocyanate is replaced much more rapidly than nitrite from these cobalt(m) centres. Substitution at bisdimethylglyoximatocobalt(m) complexes can be catalysed by cobalt(n) complexes. This has been demonstrated by the elucidation of the rate law for the cobalt(n)-catalysed reaction of trans-[Co(dmgH)2(PPhs)(NOa)] with pyridine ... 

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