A Thermodynamic Study of Some Complexes of Metal Ions with Polyamines

Journal Article · 31 March 1958 · Journal of Physical Chemistry

DOI: https://doi.org/10.1021/j150562a018 · OSTI ID:4312996

Bertsch, Charles R. ^[1]; Fernelius, W. Conard ^[1]; Block, B. P. ^[1]

---

1. Pennsylvania State Univ., University Park, PA (United States)

The dissociation constants of the following amines have been determined at 10°, 20°, 30°, and 40°: N,N,N', N'-tetramethylmethanediamine (I), 1,3- propanediamine (II), 1,4-butanediamine (III), cis- and trans- 1,2cyclohexanediamines (IV and V, resp.), 2,2',2"triaminotriethylamine (VI), and 1,3-diamino-2-propanol (VII), and at 10° for trans(?)-1,2-cycloheptanediamine (VIII). Formation constants and enthalpy and entropy changes have been determined for the following II with Ag⁺, Cu⁺⁺, and Ni⁺⁺; III with Ag⁺; IV and V with Cu⁺⁺, Ni⁺⁺, Zn⁺⁺, and Cd⁺⁺; VI with Cu⁺⁺; and VII with Ag⁺ and Ni⁺⁺ at the four temperatures. Formation constants have been determined for VIII with Cu⁺⁺, Ni⁺⁺, Zn⁺⁺, and Cd⁺⁺ at 10°. These quantities are compared from one ligand to another with the same metal ion. The difference in stability for the formation of different sized rings is primarily an entropy effect which is related to the strain introduced in the ring and the loss of freedom of the diamine in the chelate. The chelates formed with the cyclic diamines are generally more stable because of a more favorable entropy effect; however, there appear to be exceptions when the metal ion is not the proper size to fit a given diamine and weaker bonds result. Finally, an ion-exchange process for preparing diamine solutions directly from diamine salts is described.

• Research Organization: Pennsylvania State Univ., University Park, PA (United States)
• Sponsoring Organization: US Atomic Energy Commission (AEC)
• NSA Number: NSA-13-002734
• OSTI ID: 4312996
• Report Number(s): NYO--6591
• Journal Information: Journal of Physical Chemistry, Journal Name: Journal of Physical Chemistry Journal Issue: 4 Vol. 62; ISSN 0022-3654
• Publisher: American Chemical SocietyCopyright Statement
• Country of Publication: United States
• Language: English