
TY  - JOUR
A1  - Crea, J 
A1  - Lincoln, SF 
A1  - Williams, EH 
T1  - The exchange of dimethyl methylphosphonate on Pentakis(dimethyl methylphosphonate)dioxouranium(VI) ion
JF  - Australian Journal of Chemistry
JO  - Aust. J. Chem.
Y1  - 1976
VL  - 29
IS  - 10
SP  - 2183
EP  - 2188
KW  - 
UR  - https://doi.org/10.1071/CH9762183 
N2  - The greatly predominant dioxouranium(V1) species existing in the presence of perchlorate anions in dilute dimethyl methylphosphonate (dmmp) solutions in CH2Cl2 diluent is shown from 1H N.M.R. studies to be [U02(dmmp)5]2+. Lineshape analyses of exchange-modified 1H N.M.R. lineshapes show the rate of dmmp exchange to be consistent with the rate law: kex5[U02(dmmp)52+] over a 9.7-fold variation of [dmmp]. A typical set of rate parameters is kex(268 K) = 82 ± 5 s-1, &#916;H? = 57.3 ± 1.0 kJ mol-1 and &#916;S? = 6.3 ± 3.6 J k-1 mol-1 for a solution in which [U02(dmmp)52+], [dmmp] and [CH2Cl2] are respectively 0.104, 0.515 and 13.59 mol dm-3. The mechanism of the exchange process, which is considered to be predominantly dissociative in nature, is discussed. 
ER  -

