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Co n chloro complexes were studied in MeOH at 25 ~ and at constant ionic strength of 1 tool dm 3. Formation of three complexes is postulated for which the overall stability constants are calculated: log/~1=1.2, log/~2 = 1.7 and log fi3 = 1.4. The electronic spectra and the formation curves of the identified species are presented for the first time in this medium. The results are compared with those obtained in other alcohols and increasing stability with increasing molecular weight of the solvents is established. Further comparative study showed that the maximum stability of the chloro complexes is found with the Cu n ion as the central atom. This confirms the IrvingWilliams order of stabilities for the first transition metal complexes in this alcoholic medium and the result is explained in terms of the second ionization potential of the elements.

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. IntroductionThe copper( 11) chlorides have been extensively studied in aqueous and nonaqueous solutions, as have the bromide complexes, although to a lesser extent. The results of studies carried out at constant ionic strength are definitely divergent, and few allusions have been made to the more highly substituted halide complexes.

The aqueous solubilities of five chlorophenols and three nitrophenols were measured by conductimetry at temperatures between 15 and 48 °C. The solubilities of 2-chlorophenol, 4-chlorophenol, 2,4-dichlorophenol, 2,4,6-trichlorophenol, pentachlorophenol, 2-nitrophenol, 4-nitrophenol, and 2,4-dinitrophenol were studied. Automatic conductivity measurements allow the determination of the solute concentration and, hence, the determination of the solubility. Emulsion formation can also be followed. Results obtained are in good agreement with literature values.

HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

(o-Hydroxypheny1)methylphosphonic acids are readily obtained from o-(bromomethy1)-or o-(hydroxymethy1)phenols and trialkyl phosphites. Subsequent hydrolysis leads to the corresponding phosphonic acids. For a series of such compounds, the pK, values have been determined by potentiometry. Their dependence on additional substituents in the aromatic ring is discussed in terms of electronic and steric effects.

HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

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