et al. Phase transitions in solids, studied by adiabatic calorimetry. IIn the far-IR region for all the complexes only one band is present in the 188-159 cm-' range attributed to v(Cd-N) vibrational mode2. The ligand behaves as monodentate N-bonded and the complexes have a polymeric tetrahedral stereochemistry, with the exception of the monomeric perchlorate compound. The Cd(3,5-diPhisox),X2 (X = CI, Br, I) are monomeric distorted tetrahedral with monodentate N-bonded ligand.
Mercury( 11) complexesThe mercury complexes are of type 1 : 1, 1 : 2 and 1 :4. In the Hg(PPO)X, derivatives the bands present at 244 and 198 cm-' are due to v(Hg-Br) and v(Hg-I) terminal respectively, while the bands at 184 and 143 cm-' are attributed to bridging halide in accord with the literature data".". These complexes are non-electrolytes in MeOH. The Hg(PPO), (NO,), shows in the near -1R region the bands at 1290 (v,), 1070(v2), 1385(v,), 1760(v, +v,) and 1735(v2 +v,) cm-', that clearly are due to stretching, bending and rocking of monodentate nitrate groupsL2. The band at 170 cm-' is assigned to v(Hg-ON02)'b. This complex, insoluble in MeOH, has in D M F an anomalous molar conductivity value of 80 cm2R-' mole-'. This fact is attributed to partial displacement of nitrate groups by the solvent molecules.The Hg(PPO),(C104),.2 H 2 0 presents in the near -1R characteristic bands of C10,-ionic at 1085 cm-' (vj) and at 630 cm-' (v,)". The molar conductivity value is typical of 1 : 2 electrolyte. In the spectra of all the complexes new bands are present at -148 cm-' due to metal-ligand interaction through the nitrogen atom19. The mercury derivatives are monomeric tetrahedral as the Hg(3,5-diPhisox),X2 derivatives (X = CI, Br); the iodide PPO compound is polymeric, while the nitrate and perchlorate derivatives are monomeric.
ConclusionsPreviously', the preparation of some complexes of cobalt( II), copper(l1) and nickel (I1) (I1) and Cd(II), respectively, but a different stereochemistry. The complexes of copper(II), nickel(I1) and cobalt(1I) with 3,5-diPhisoxzo, have generally stoicheiometry and stereochemistry similar to the PPO ones, which ligand behaves as monodentate or bridging bidentate. In the derivatives of zinc(II), cadmium(I1) and mercury(II)2 3,5-diPhisox acts always as monodentate N-bonded and the stereochemistry of these complexes is always distorted tetrahedral. We can conclude that the different position of the phenyl groups and donor atoms seems to have no noticeable influence on the coordination behaviour of the ligand. Abstract. The construction of an automatic adiabatic calorimeter is described. A block diagram is given of the data-logging system used. n-Heptane is used to check the performance of the apparatus.
IntroductionAmong the subjects we wish to study with adiabatic calorimetry are phase transitions in solids, specific heat values and especially, phase diagrams of binary systems.
