Detailed Spectrophotometric Study of Copper(I1) Halides in Anhydrous Methanol
Résumé
A spectrophotometric study of the copper(I1) chlorides and the copper(I1) bromides in anhydrous methanol was carried out at 25 "C and at constant ionic strength (1 mo1.L-I). A matrix rank treatment of the experimental data followed by the testing of different theoretical models confirmed the presence of four mononuclear complexes for both systems, viz. C u X ' , CuX2, CuX3-, and CuXz-. Overall stability constants calculated for the chlorocuprates are PI = 2.8 X lo2, b2 = 1.6 X IO4, 8, = 2.3 X los, and P4 = 4.5 X lo5 and for the bromocuprates are PI = 5.2 X lo', P2 = 3.9 X IO5, P3 = 2.0 X lo6, and b4 = 2.1 X lo6. Individual electronic spectra of all species in methanol are reported for the first time. In this solvent the tetracoordinated chloro complex exhibits a calculated absorption maximum in the near-IR region consistent with a square-planar structure, in contrast to the structure in the solid state, while for the tetrabromocuprate the structure of a flattened tetrahedron is confirmed.
Domaines
Chimie
Origine : Accord explicite pour ce dépôt