INORGANIC COMPLEX COMPOUNDS CONTAINING POLYDENTATE GROUPS
Aug. 20, 1957
FORMATION CONSTAXT Car.
x
fiH
CHCl
x
104
4.505 4.484 4,464 4.405 4.386
4.26 4.29 4.33 4.39 4.44
TABLE IV METHOD O F BJERRUM FOR T H E EQUILIBRIUM B E T W E E S S I C K E L ( 11) AND TETREN AT 25’ me CT - C’T
CALCULATED BY
CT 4,505 4.484 4.464 4.405 4.386
103
1.014 0.9524 .8929 .7154 .6579
CA
PZT
0.9590 ,9011 ,846 1 .6747 .6216
3.547 3.527 3.502 3.464 3.433
may be illustrated by the equation Ki2+
+ tetrenH:+
[Ki HtetrenI3+ f 3H+
The formation constant for the “hydrogen” complex formed in this process was calculated, the results being given in Table 111. The agreement of the formation constants calculated from the “Excess-metal ion” curve and the “Equivalent” curve indicates that no polynuclear complexes are formed. Thus for the over-all neutralization process and complex formation the following equations are descriptive. tetrenHg+
+tetrenH:+ - H+
k-izt ^ . I
SiHtetrena+
-3H+
+ - H+
?iitetren2+
[CONTRIBUTION FROM T H E
PERCHLORATE
9T
17.91 17.83 17.71 17.59 17.45
1,801 1.929 2.048 2 457 2.570
4279
0.40 .43 .46 .56 .59 Av. log K
K 17.73 17 70 17.69 17.69 17.60 17.68
log
The formation constant for Nitetren2+obtained by the method of Bjerrum is in excellent agreement with that obtained by the method of Schwarzenbach; however, the former method does not yield formation constants for the “hydrogen complex.” Attempts also were made to measure the formation constants polarographically, but due to irreversibility of the system this method was unsuccessful. Thermodynamic data calculated from the variation of log K with temperature are no more accurate than the reliability limits of the constants and hence are not reported. Acknowledgments.-The authors wish to thank the Office of Ordnance Research U. S. Army for the support of this and continuing investigations. NEWORLEANS 18, LOUISIASA
RICHARDSON CHEMISTRY LABORATORS AT TULANE UNIVERSITY]
Inorganic Complex Compounds Containing Polydentate Groups. XVI. A Study of the Complex Ions Formed by the Copper(I1) Ion with Triethylenetetramine, Tetraethylenepentamine and Pentaethylenehexaminel BY HANSB.
JONASSEN,
J. AARONBERTRAND, FRANK R. GROVES,JR.,
AND
ROBERTI. STEARNS
RECEIVED APRIL 6, 1957 T h e complexes of the copper(I1) ion with triethylenetetramine, tetraethylenepentamine and pentaethylenehexamine have been studied polarographically. It has been shown t h a t the copper(I1) ion exhibits an amine coordination number of five with these compounds and t h a t hydrogen complexes are formed.
( E I / ~-) (E1/Js ~ = 2 303 R T / n F log K , 2.303 R T / n F p log C,
Introduction
The polarographic study of complex ions is a well established method2 provided that the complex ion Where to be investigated is reduced reversibly a t the dropping mercury electrode. If a plot of E d . e . versus the corresponding values of log ( i d - i)/i KO from equation I is a straight line with slope 2.303 p ( R T / nF ) the reduction process is reversible. E d e. =
El/,
+ 2.303 R T / n F log
(id
- i)/i
(1)
Where Ed.e. = voltage a t t h e dropping mercury electrode El/, = half-wave potential of t h e complex i , ~ = diffusion current i = current a t a n y & . e . n = number of electrons transferred
The composition of the complex can be determined from the equation (1) Abstracted in p a r t from t h e Master’s Theses submitted t o Tulane University, Iiew Oileans, Louisana, b y J. Aaron Bertrand, 1956, F r a n k R . Groves, J i . . 1951, a n d R o b e r t I. Stearns, 1955. (2) I. M. Kolthoff, “Polarography,” Interscience Publishers, New York, N. Y., 1952.
C,
(11)
half-wave potential of the complex half wave potential of the simple aquo metal ion = dissociation constant of t h e complex = no. of moles of ligand per mole of metal ion in t h e complex = concn. of ligand in moles/l. (C, must be in considerable excess over the concn. of the metal ion in order t h a t the concn. of t h e simple aquo metal ion will be negligible,) =
=
A plot of ( E T I J ~of’ S several solutions of varying C, versus log C, will yield a straight line of slope 2.303 RT/nFp from which p can be calculated. Using the value of fi established in equation I1 p K , can be calculated. The polyamines which become protonated to varying degrees depending upon the pH of the solution become a special case. Their dissociation occurs as shown in the reaction H.(HqX)p+(z’*)Jr z H - f PHqX+R
H. B. JONASSEN, J. -1. BERTR-IND,F.I pure), white label, EastA . Reagents.-Pngl man Kodak Company was used without further purification. ( I ) Abstracted in p a r t from a thesis submitted by Elwood J G u n zales t o t h e Tulane University i n partial fulfillment of t h e requirem e n t i fr,r t h e degree of hl;i.ter [ i f Science ( 2 ) G T. 1 f o i g a n a n r l J I3 Xfain-Smith. J C h e m S o c , 7 0 t ( 1 9 2 1 ) . (,'O
