
TY  - JOUR
A1  - Anderson, PA 
A1  - Creaser, II 
A1  - Dean, C 
A1  - Harrowfield, JM 
A1  - Horn, E 
A1  - Martin, LL 
A1  - Sargeson, AM 
A1  - Snow, MR 
A1  - Tiekink, ERT 
T1  - Synthesis, Resolution and Kinetics of Electron Self-Exchange of High-Spin Manganese(II)/(III) Cage Complexes
JF  - Australian Journal of Chemistry
JO  - Aust. J. Chem.
Y1  - 1993
VL  - 46
IS  - 4
SP  - 449
EP  - 463
KW  - 
UR  - https://doi.org/10.1071/CH9930449 
N2  - The ligand sarcophagine ( sar = 3,6,10,13,16,19-hexaazabicyclo[6.6.6] icosane ) rapidly reacts with [ Mn (OH2)6]2+ to form the nearly colourless [ Mn ( sar )]2+ ion, which can readily be oxidized to the bright orange [Mn ( sar )]3+ ion (E&#176;&#8242;+0.53 V v. n.h.e. in 0.1 mol l-1 CF3SO3H at 295 K). A single-crystal structure determination on [ Mn ( sar )](NO3)3, space group I 42d, a 15.549(6), c 19.014(6) &#506;, R 0.051, Rw 0.049 for 608 'observed' reflections, shows the coordination geometry of the manganese(III) ion, with site symmetry 2, to be subject to a Jahn-Teller distortion, giving three pairs of Mn -N bond lengths of 2.18(1), 2.13(1) and 2.08(1)&#506;. The [ Mn ( sar )]3+ ion is stable in strongly acidic aqueous solutions, but in solutions of pH > 3 undergoes deprotonation and subsequent disproportionation reactions. The manganese(II) complex ion is less stable in acidic solutions, undergoing hydrolysis at a rate showing a first-order dependence on both proton and chloride ion concentrations. Both [ Mn ( sar )]2+ and [ Mn ( sar )]3+ can be obtained in chiral forms, and the rate constant for electron self-exchange obtained by polarimetric measurements on solutions of mixtures of [ Mn ( sar )]2+ and [ Mn ( sar )]3+ of opposite chirality is 30 dm3 mol-1s-1 at 298 K, I = 0.1 M. 
ER  -

