The enthalpies of the reactions of the title tetraamines H2N(CH2)nNH(CH2)mNH(CH2)nNH2 (I) with H, Cu(II), Ni(II), and Zn(II) ions in 0.5M KNO3 at 25° were detd. by direct calorimetric titrns. The entropy change ΔS values were calcd. from known free energy change ΔG values. The heats of formation of the complexes of I (n = 3, m = 2) which contain a system of condensed chelate rings with the ring sequence 6,5,6, i.e. II (M = Cu, Ni, Zn) were higher than those of the corresponding complexes of I (n = m = 2) (ring-size sequence 5,5,5) and of I (n = m = 3) (ring-size sequence 6,6,6). Cu(II) and Zn(II) complexes of II had a less neg. heat of formation ΔH than the complexes of I (n = 2, m = 3), which has the ring-size sequence 5,6,5.
Thermodynamics of complex formation with linear aliphatic tetraamines. III. Enthalpy and entropy contributions to the stability of metal complexes of 4,7-diazadecane-1,10-diamine
FABBRIZZI, LUIGI;
1973-01-01
Abstract
The enthalpies of the reactions of the title tetraamines H2N(CH2)nNH(CH2)mNH(CH2)nNH2 (I) with H, Cu(II), Ni(II), and Zn(II) ions in 0.5M KNO3 at 25° were detd. by direct calorimetric titrns. The entropy change ΔS values were calcd. from known free energy change ΔG values. The heats of formation of the complexes of I (n = 3, m = 2) which contain a system of condensed chelate rings with the ring sequence 6,5,6, i.e. II (M = Cu, Ni, Zn) were higher than those of the corresponding complexes of I (n = m = 2) (ring-size sequence 5,5,5) and of I (n = m = 3) (ring-size sequence 6,6,6). Cu(II) and Zn(II) complexes of II had a less neg. heat of formation ΔH than the complexes of I (n = 2, m = 3), which has the ring-size sequence 5,6,5.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
