Triazacyclononanes, chromium complexes

Kinetics of decarboxylation of x-carbonato complexes have been studied for the 1,4,7-triazacyclononane (LLL) complexes (45), with M = Rh or Cr. Both components of the right-hand side of the expression kobs = ki + A 2[H ] are important for the chromium(III) compound, but only the acid-catalyzed path is significant for the rhodium(III) compound. Rate constants and activation parameters are extremely similar for the k2[H ] paths for rhodium(III) and for chromium(III), consistent with the expected carbon-oxygen bond rupture in the rate-determining step. The kinetic parameters here are also, of course, very... 

An interesting class of capping reagents based on 3d metal complexes of 1,4,7-triazacyclononane has recently been discovered [111-113], It is well known that manganese(III), iron(III) or chromium(III) form octahedral complexes with 1,4,7-triazacyclononane or its derivatives with 1 1 stoichiometry [114]. The macrocyclic amine in these complexes has been shown to be coordinated facially to the central metal ion, the remaining three coordination sites being occupied by monodentate ligands. The latter, in contrast to the tridentate macrocyclic amine, can easily be... 

Copper(I) complexes show a lamellar structure not conclusively assigned [175]. Liquid crystalline complexes with chromium, molybdenum and tungsten as metallic centers have also been reported. The 1,4,7-trisubstituted 1,4,7-triazacyclononane and three carbonyl groups, 80, are coordinated in an octahedral geometry. 

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