A Thermodynamic Study of Some Complexes of Metal Ions with Polyamines

Abstract

The value of An at 27°is a measure of the amount of decomposition product still gaseous at room temperature. The fact that An at 27°is still large, in many cases, indicates that at least some of the decomposition products are of low molecular weight. The nature of the volatile decomposition products for certain of these compounds is currently being investigated. The results of this study will be reported in a later paper.The nature of the solid residues obtained from the decomposition of the acetylacetonates was not determined. In general the change in appearance of the chelates paralleled the extent of decomposition, as indicated by An. Those acetylacetonates undergoing extensive decomposition generally gave very dark colored, and frequently resinous, residues. It is planned to study the nature of some of these materials.Acknowledgment.-The authors are grateful to Miss . I. Mistrik for certain of the analyses.

Structure of bis(2,2',2''-triaminotriethylamine-N,N',N'')-μ-(triethylenetetramine-N,N',N'',N''')-dinickel(II) tetraperchlorate

“…In the water exchange study, two different exchange rates were observed, leading the authors to propose a cis-octahedral arrangement for the Ni(tren)(H20)~ + species. Other authors have suggested tetrahedral (Bertsch, Fernelius & Block, 1958) or trigonal bipyramidal (Jonassen & Thilemann, 1963). In this paper, we present solid-state structural results for the compound bis (triaminoethylamine)(triethylenetetramine)dinickel(II) perchlorate, C~sHs4NI2Ni4+.4C10~ (I), supporting the concept of a cis-octahedral arrangement.…”

Interplay of thermochemistry and Structural Chemistry, the journal (volume 16, 2005) and the discipline

“…The structure of synthesized compound contains a novel example of hexafurcated (acceptor) hydrogen bonds and accompanying three-dimensional channel assembly. We note that measurements of the complexation enthalpies and entropies for cis-and trans-1,2-diaminocyclohexane with Ni(II) as well as with other divalent metals have been reported [183].…”

Fletcher–Powell minimization of analytical potentiometric data by microcomputer: application to the Cu(II) complexes of biological polyamines

“…The complexes of Cu(l1) and Ni(1I) with 1,3-propanediamine are much less stable than those with 1,2-ethanediamine. The -AH values for binding are larger with propanediamine, in keeping with its stronger basicity, but the stabilities are dominated by the more favorable entropy change when the 5-membered ring is formed (29). Loss of freedom of the ligand is so great with 7-membered ring formation that 1,4-butanediamine (putrescine) does not form Cu(II), Ni(II), or Zn(I1) complexes in aqueous solution (29), although these complexes can be isolated from absolute alcohol (30).…”

“…The -AH values for binding are larger with propanediamine, in keeping with its stronger basicity, but the stabilities are dominated by the more favorable entropy change when the 5-membered ring is formed (29). Loss of freedom of the ligand is so great with 7-membered ring formation that 1,4-butanediamine (putrescine) does not form Cu(II), Ni(II), or Zn(I1) complexes in aqueous solution (29), although these complexes can be isolated from absolute alcohol (30). It has been estimated (24) that diamine-Cu(l1) chelate rings of 5, 6, and 7 members add respectively 5.3-7.0, 4.6-6.1, and 2.0-3.0 to the log K , value for complex formation.…”

“…The series H2N-(CH2)2-[NH-(CH2)d,,-NH2, beginning with ethylene diamine (11 = 0), serves as the most straightforward example of the effect of the number of chelate rings on complex stability (28), while the bidentate diamines H2N-(CH2),,-NH, demonstrate the role of ring size (29). The complexes of Cu(l1) and Ni(1I) with 1,3-propanediamine are much less stable than those with 1,2-ethanediamine.…”