Kinetics of the reaction of copper(II) with meso-5,7,7,12,14,14-hexamethyl-1,4,8,11-tetra-azacyclotetradecane
- 1 January 1977
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in J. Chem. Soc., Dalton Trans.
- No. 12,p. 1148-1152
- https://doi.org/10.1039/dt9770001148
Abstract
Copper(II) reacts with meso-5,7,7,12,14,14-hexamethyl-1,4,8,11-tetra-azacyclotetradecane (L1) in aqueous solution (pH 4–6) to give [CuL1]2+(blue) with λmax. 620 nm, At higher pH (ca. 9), [CuL1]2+(blue) is slowly converted into [CuL1]2+(violet) with λmax. 520 nm. The kinetics of formation of the blue complex have been studied at 25 °C and I= 0.1 mol dm–3 in both acetate and piperazine-NN′-bis(ethane-2-sulphonic acid) buffers. In the absence of acetate, Rate =k1[Cu2+][HL1+] but in acetate buffers Rate =k1[Cu2+][HL1+]+k2[Cu(O2CMe)][HL1+]+k3[Cu(O2CMe)+][H2L1 2+], with k1= 3.6 × 103 dm3 mol–1 s–1, k2= 1.8 × 104 dm3 mol–1 s–1, and k3= 1.5 × 10–2dm3 mol–1 s–1. Possible mechanisms for the reaction are considered.Keywords
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