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Studies on post-transition metal complexes with macrocyeles in solutions
김호두 Chosun Univ. 1992 국내박사
In this study, both potentiometry and calorimetry were used as the means of determination of post transition metal binding constants for the cyclam, tetramethylcyclam, diaza-18C6, cryptand 221, cryptand 211, 14-ane-S_(4), 16-ane-S_(4),16-ane S_(4)-diol, dithiacyclam, and new synthesized side-arms macrocycles such as tetrapyridinecyclam, tetraaceticcyclam and diaceticdithiacyclam, and both spetrometry (NMR)and spectrophotometry(UV/Vis. and IR) were used to confirm the structures and characteristics of cadmium(II) complexes with the macrocycle ligands. New Protonation and binding constants of the complexes and the macocycles have been determined in pure water and methanol-aceton solvents. these values were checked within experimetal error by using the computer programs. Protonation constants of the side arms macrocycles are more increased than the other macrocycles. The L_(4) ligand in the side-arms macrocycles is observed in reaction of hexaprotonation and the pK values is the highest. The first two pK values apply to cyclam protons in macrocycle cavity, and the last four are carboxyl protons. The binding constants of transition metals except Zn(II) are higher than that of other metals. Having the comparison with other metals. Having the complexes with other matal ion complexes with L_(1)-L_(12) macrocycles, the stabilities are the highest because entropy effect is increased by forming the complexes with Hg(II) metal ion. Also meta1 binding constants with side arms-macrocycles are more increased than the others. The soft metal, Hg(II), stabilities with L_(5) and L_(6) containing the two sulfur donor atoms are exceedingly increased as contrasted with the other metals and macrocycles. and also the stabilities with thioehers, L_(10)-L_(12) are higher than those of the other post transition metals. The formation enthalpy of the post metal ion complexes with are higher 16-ane-S_(4)-diol, L_(12), is more decreased than that with 16-ane-S_(4) such as L_(11). Less favorable ΔH and are TΔS terms for the OH site reaction indicate that the difference do exist between L_(11) and L_(12). The basicity of L_(12) is more decreased than that of L_(11) by containing OH site with electron affinity. and the mcrocyclic effect has also not been in the post metal ion complexes with thioehers such as L_(10)∼L_(12). We found that there are some factors such as metal ion characteristics, steric and electrostatic effects by side-arms, kinds of macrocycles and formation entropy effect to affect the stability of post transition metal complexes with macrocycles. The mole rations of metal to macrocycles calculated by calorimetry and potentiometry were 1:1 in solution. and also the mole-rations of cadmium(II) complexes in solid state were 1:1. The molar electric conductivities of the complexes in water and acetonitrile were in range of 236.8∼296. 1 ㎠ mol^(-1) ohm^(-1) at 25℃. All complexes are obtained for 1:2 electrolytes 4 chemical formular of the complexes is a CdL(NO_(3))_(2). The characteristic peaks of guest(Cd) induced from macrocycles were shifted to lower frequencies for mcrocycles. A complex with tetraaceticcyclam, L_(4), exhibits two bands such as strong streching (1646?^(-1)) and weaker symmetric stretching band(1384^(-1)). therefore, interaction of metal ion with a carboxylate can be occur with variety orientation. ^(1)H and ^(12)C NMR studies which indicated the nitrogen and sulfur donor atom of ring has greater affinity to Cadmium(II) metal ion than dose the oxygen atoms, and the planities of macrocycles are lost by complexation with metal ion. Also, it was pointed out coordinate characteristics of side arms group bridgeheaded in macrocycles. The ^(13)C-resonance of methylene nighboring the donor atom such as N and S were shifted to a direction of high magneticfield and the order were L_(1)<L_(2)<L_(3)<L_(6)<L_(4). Also these values were larger than shifts of ^(13)C-resonance bridgeheaded in side-arms groups. and ^(13)C NMR spectrum of the complex with L_(12) reveals the presence of two sets of three resonances, each set having the expected intensity is the ratio of 1:2:2. This behavior is consistent with a dynamic equilibrium between two of the five possible ligand conformation predicted for sqare-planer or tetragonal complex to be formed by coordinating four sulfur atoms and other nonbonding electron pairs of OH group.