
%0 Journal Article
%A Bernhardt, Paul V. 
%A Hambley, Trevor W. 
%A Lawrance, Geoffrey A. 
%A Maeder, Marcel 
%A Wilkes, Eric N. 
%T Isomers of 1,4,8,11-Tetraazacyclotetradecane-6,13-dicarboxylate Characterized as Cobalt(<emph type="6">III</emph>) Complexes
%J Australian Journal of Chemistry
%D 2003/06/30
%V 56
%N 7
%P 679-684
%K 
%R https://doi.org/10.1071/CH02246
%U https://www.publish.csiro.au/paper/CH02246 
%X The major trans (1) and minor cis (2) isomers of 1,4,8,11-tetraazacyclotetradecane-6,13-dicarboxylate have been characterized as the complexes [Co(1)](ClO4) and [Co(H2)(OH2)]Cl(ClO4)&#183;H2O. The former crystallized in the C2/c space group and the latter in the P21/c space group, with cell parameters a 16.258(7), b 9.050(3), c 15.413(6) &#197;, &#946;133.29(3)&#176;, and a 9.694(4), b 16.135(1), c 12.973(5) &#197;, &#946; 93.00(2)&#176;, respectively. Their characterization completes identification of the respective trans and cis isomers for the series of c-pendant macrocycles also including 1,4,8,11-tetraazacyclotetradecane-6-amine-13-carboxylate ((3), (4)) and 1,4,8,11-tetraazacyclotetradecane-6,13-diamine ((5), (6)). The complexes show limited distortion from octahedral geometry with the strain in the presence of the coordinated c-pendant carboxylate significantly reduced compared with that for the c-pendant amine in analogues, a consequence mainly of six-membered as opposed to five-membered chelate rings involving the pendant donor. A comparison of the physical properties for the trans isomers of the octahedral complexes of (1), (3), and (5), which reflect progressively increasing strain, is presented. 
