
TY  - JOUR
A1  - Baran, Yakup 
A1  - Hambley, Trevor W. 
A1  - Lawrance, Geoffrey A. 
A1  - Wilkes, Eric N. 
T1  - Syntheses and Comparative Base Hydrolysis Reactions of Chlorocobalt(III) Complexes of Pendant-Arm Macrocyclic Polyamines and Polyamino Acids
JF  - Australian Journal of Chemistry
JO  - Aust. J. Chem.
Y1  - 1997
VL  - 50
IS  - 9
SP  - 883
EP  - 888
KW  - 
UR  - https://doi.org/10.1071/C96196 
N2  - Chlorocobalt(III) complexes of the pendant-arm macrocycles 1,4,8,12-tetraazacyclopentadecane-10-carboxylate (2) and 1,5,9,13-tetraazabicyclo&#91;11.2.2&#93;heptadecane-7-carboxylate (4) have been prepared to complement the known complexes of 10-methyl-1,4,8,12-tetraazacyclopentadecan-10-amine (1) and 7-methyl-1,5,9,13-tetraazabicyclo&#91;11.2.2&#93;heptadecan-7-amine (3). The pairs (1),(3) and (2),(4) differ in replacement of pendant amine and methyl groups in the former pair by a pendant carboxylate group and hydrogen in the latter pair. The macromonocyclic ligands (1) and (2) form cis-chlorocobalt(III) complexes whereas the macrobicyclic ligands (3) and (4) (which contain an additional &#8211;CH2&#8211;CH2&#8211; &#8216;strap&#8217; linking two amines) form trans-chlorocobalt(III) complexes, defined in terms of location of the pendant donor and the chloride donor. Chloride base hydrolysis kinetics varies with ligand &#123;cis-&#91;Co(1)Cl&#93;2+, kOH 6700 dm3 mol-1 s-1 ; cis-&#91;Co(2)Cl&#93; +, kOH 1800 dm3 mol-1 s-1;trans-&#91;Co(3)Cl&#93;2+, kOH 3450 dm3 mol-1 s-1; trans-&#91;Co(4)Cl&#93;+, kOH 2250 dm3 mol-1 s-1 at 25&#176;C&#125;. Variations in rate constant are tied mainly to variations in activation enthalpy. Chloride hydrolyses occur with retention of configuration, but slow following isomerization can lead to products such as trans-&#91;Co(2)(OH2)&#93; (ClO4)2.2H2O, which crystallizes in the monoclinic space group P21/c, a 9&#183;581(2), b 16&#183;214(2), c 14&#183;350(2) &#197; and &#946; 94&#183;66(1)&#176;. The pendant carboxylate group and two adjacent secondary amines necessarily occupy an octahedral face, with the water molecule bound trans to the pendant carboxylate. The four Co&#8211;N distances range from 1&#183;981(2) to 2&#183;22(3) &#197;, and along with carboxylate Co&#8211;O (1&#183;882(3) &#197;) and water Co-O (1&#183;934(2) &#197;) distances are similar to usual distances in cobalt(III) complexes. 
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