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Investigations with ion-exchange papers
640 Investigalions
XOTES
with ion-exchange
II. Studies on some metal
papers
ion-thiocyanate
complex
systems
The aim of this work is to survey the anion exchange behaviour of thiocyanate complexes of metal cations belonging to the transition series as well as to the transitional and post-transitional. groups. This was clone by chromatography on the folNo. I; Whatman AE-Sr, aminoethyl cellulose anion lowing papers : Whatman exchange paper ; Whatman DE-Sr , cliethylaminoetl~yl cellulose anion exchange paper ; SB-z(Rohm and Haas), cellulose loaded with the strongly basic anion exchange resin Rmberlite IRA-400. The anion exchange papers were used in the SCN- form, Metal nitrates (dissolved in aqueous KSCN at the appropriate concentrations) were spotted on the paper strips, and the ascending developments were carried out with the eluent aqueous ICSCN at varying concentrations. The latter had pH w I (obtained with aqueous HSCN, which was prepared by cation exchange) where it was necessary to avoid hydrolysis. The chromatographed metal ions were revealed on the strips by the colour of the corresponding thiocyanate complexes (V02*, Fe( III), Co( II), Cu(II)), or by using labellecl metal nitrates ancl scanning or autoradiography (for fl”Zn(II), 2”3Hg(II), rlOmAg(I), ll’~mIn(III), 2”4Tl(I)), or by spraying with an appropriate reagent]. The chromatographic runs of the system Cu(SCN),2;” were stopped just before the disappearance on the strips of the brown colour due to the complex (owing to Cu(I1) rccluction2). Further experimental details are given elsewhere3. The results are reported in Fig. L. La(II1) and Sm(III), not shown in l?ig. I, travelled to the solvent front with every paper and every ligand concentration, From the Rp of Fig. I, simple and rapid separations of metal ion mixtures can be devised. While this work was in progress, a paper by LEDERER et al.‘1 appeared on the distribution of metal cations between anion exchange papers ancl aqueous HSCN. The findings of LEDERER et al. ancl ourselves, concerning the metal ions investigated under about the same experimental conditions, are practically identical. The retentions reported in Fig. I may be ascribed to anion exchange of thiocyanate complexes, since the investigated metal ions (Mm+) form well-known M(SCN);:‘-” species5. The RF data of Fig. I thus provide useful information to plan anion e.xchange research on such systems. In fact, by taking into account the relation between Rp and clistribution coefficientrva(D), it may be assumed that the complex systems showing a displacement ranging from just a measurable one (e.g., R#- - 0.05) toRF ‘y 0.5, will have D values which can be measured by means of standard anion exchange techniques i.e., column and equilibration procedures). Therefore it seems possible to foresee that the following studies on M(SCN);:-” complexes in aqueous solution could be carried out with anion eschangers: (I) With strongly basic anion exchange resins (such as Amberlite IRA-+o) : complexes of Sc(III), Mn(II), Ag(I), Cd(II), Ga(III), Tl(1). (2) With AE cellulose anion es&angers: complexes of Cu(IIj, Ag(I), Zn(II),
Hg(II) .
(3) With DE cellulose anion exchangers: complexes of VO2+, Fe(III), Co(II), Cu(II), Ag(I), %n(II), Hg(II), In(II1). That reportecl uncler (I) has no need for comment. We demonstratecl earlier that strongly basic anion exchange resins are fairly well suited for the cletermination
J. Clrlw?m7l0g*, 30
(1907)
G40-G&p
641
NOTES
r
co cm
In (1111 (a)
VO”
(al
Nl ‘311
Mn
(111
Fe (utl (al
cu
CII)
Ag (1)
TI (1) LO 0.8
0.6 0.4 0.2 01)
#
t L--l RF
lsg[gcw~~
..t
-0.6
0
0.6
Fig. I. Distribution of metal ion-thiocyanatc complexes bctwecn aqueous KSCN and anion exchange papers. Rp values VS. log [SCN-] on: (0) Whatman No. I ; ( U) Al581 ; (I) DE-81 ; and (a) SB-2. Bottom right: rcfcrcnce chart for tile values in the co-ordinates. (a) inclicates the USC of aqueous KSCN _1- 0.1 M I-ISCN as elucnt.
of the nature, and order of the stability constants, of thiocyanate complexes in aqueous solution’. Quite recently, a paper appeared on anion exchange studies (with Dowex I) At present we are investigating the Tl(SCN):;“and of Cd(SCN)f&-!,-‘”complexes”. Pb(SCN)f,;” systems (with Amberlite IRA+oo), and have obtained D values which fit the distribution curves calculated by using tabulated values of stability constants6 and the anion exchange theory0 satisfactorily. The determined D values of Tl(1) are in good accordance with those calculated from the Xp data (on 93-2) of Fig. I. As to (2) and (3), the employment of AE and DE exchangers in such a type of investigation obviously needs a profound knowledge of their properties and behaviour, which at present seems to be missing. On the other hand, the graphs XM VS. log a function of aqueous SCN-) for Fe(III), Co(II), 11~; a = activity (RM = log (I/RF %n(II), Cd(I1) on DE, and Ag(I), I-Ig( II) on AE and DE, fit fairly well to the calculated distribution curves. The same can be saicl about the log D vs. log a graphs we recently obtained for l?e(III), Ag(I), Zn(I1) and Hg(II), by measuring the distribution of the metal cations between AE and DE (powders) and aqueous KSCN, by means of column or distribution techniques, This work is still in progress. The finclings on Hg(I1) and Tl( I) are of special interest to our research pro’ gramme. We are studying organometal-halide and -pseudohalide complexes, which are generally rather labile in aqueous solution and may be successfully investigated by J.
Ch~omnfog.,
30 (1907)
G40-542
642
NOTES
about the influence anion exchange idle--12.The aim of the work is to get information of organic radicals, bound to the metal atom, on the tendency of the latter to coordinate, Anion exchange stability constants of the corresponding metal ion complexes are then needed, and the best comparison is obviously effected between values obtained with the same method. The reason why we are studying the cellulose exchangers is that it seems possible to employ AE and DE for anion exchange studies of arylmetal complexes. In fact, while the latter are adsorbed on the classical anion exchange resins by a mechanism probably different from anion exchanger”, their behaviour on AE and DE appears to he quite normal”J’t. The authors would like to acknowledge delle Ricerche.
CentjBo da’ Chimica delle Radiazioni e dei Radioelemmh’ de1 CNR, Padova (Italy)
4 j G 7 S 9 IO I I
12 13
14
Received J.
of the Consiglio
GIUSEPPE
Nazionale
RIZZARDI
CJ~rol?zalo~~~~~J~y, Elsevicr, knstcrda~n, 1957. Ckem, So&, 109 (1916) ,597. G. FARAGLIA, A. CASS~L AND R. BAIU~~~R~, PYOC. Jo~mades IJclZb~zes de S+wratiou Iwnddialc cl de Cltro~rzatogva~hie (IT1 J.I.S.I.C.).Ass. Greek Chcrn. Ed., hthcns, 1966, p. 271. G. BAGLIANO, L. OSSICINI AND M. LEDERER,J, C?wo?natog., 21 (1966) 471. L. G. SILL~N AND A. E. MARTELL, Slabilif~~ Cotnsla&s of Me/al-low Comq!hxes, Pul>l. No. 17, Chcm. Sot,, London, 1gG4. 12.BARBIERI, G. I-IERRERA GUADA AND G. RIZZAI
I E. LEDERER 2 J. C. PHILIP
3
the support
AND AND
M. A.
LEDERER, BRAMLEY,
April rst, 1567
Cltwomalog.,
30 (1gG7)
G40-642
J.
XOTES
with ion-exchange
II. Studies on some metal
papers
ion-thiocyanate
complex
systems
The aim of this work is to survey the anion exchange behaviour of thiocyanate complexes of metal cations belonging to the transition series as well as to the transitional and post-transitional. groups. This was clone by chromatography on the folNo. I; Whatman AE-Sr, aminoethyl cellulose anion lowing papers : Whatman exchange paper ; Whatman DE-Sr , cliethylaminoetl~yl cellulose anion exchange paper ; SB-z(Rohm and Haas), cellulose loaded with the strongly basic anion exchange resin Rmberlite IRA-400. The anion exchange papers were used in the SCN- form, Metal nitrates (dissolved in aqueous KSCN at the appropriate concentrations) were spotted on the paper strips, and the ascending developments were carried out with the eluent aqueous ICSCN at varying concentrations. The latter had pH w I (obtained with aqueous HSCN, which was prepared by cation exchange) where it was necessary to avoid hydrolysis. The chromatographed metal ions were revealed on the strips by the colour of the corresponding thiocyanate complexes (V02*, Fe( III), Co( II), Cu(II)), or by using labellecl metal nitrates ancl scanning or autoradiography (for fl”Zn(II), 2”3Hg(II), rlOmAg(I), ll’~mIn(III), 2”4Tl(I)), or by spraying with an appropriate reagent]. The chromatographic runs of the system Cu(SCN),2;” were stopped just before the disappearance on the strips of the brown colour due to the complex (owing to Cu(I1) rccluction2). Further experimental details are given elsewhere3. The results are reported in Fig. L. La(II1) and Sm(III), not shown in l?ig. I, travelled to the solvent front with every paper and every ligand concentration, From the Rp of Fig. I, simple and rapid separations of metal ion mixtures can be devised. While this work was in progress, a paper by LEDERER et al.‘1 appeared on the distribution of metal cations between anion exchange papers ancl aqueous HSCN. The findings of LEDERER et al. ancl ourselves, concerning the metal ions investigated under about the same experimental conditions, are practically identical. The retentions reported in Fig. I may be ascribed to anion exchange of thiocyanate complexes, since the investigated metal ions (Mm+) form well-known M(SCN);:‘-” species5. The RF data of Fig. I thus provide useful information to plan anion e.xchange research on such systems. In fact, by taking into account the relation between Rp and clistribution coefficientrva(D), it may be assumed that the complex systems showing a displacement ranging from just a measurable one (e.g., R#- - 0.05) toRF ‘y 0.5, will have D values which can be measured by means of standard anion exchange techniques i.e., column and equilibration procedures). Therefore it seems possible to foresee that the following studies on M(SCN);:-” complexes in aqueous solution could be carried out with anion eschangers: (I) With strongly basic anion exchange resins (such as Amberlite IRA-+o) : complexes of Sc(III), Mn(II), Ag(I), Cd(II), Ga(III), Tl(1). (2) With AE cellulose anion es&angers: complexes of Cu(IIj, Ag(I), Zn(II),
Hg(II) .
(3) With DE cellulose anion exchangers: complexes of VO2+, Fe(III), Co(II), Cu(II), Ag(I), %n(II), Hg(II), In(II1). That reportecl uncler (I) has no need for comment. We demonstratecl earlier that strongly basic anion exchange resins are fairly well suited for the cletermination
J. Clrlw?m7l0g*, 30
(1907)
G40-G&p
641
NOTES
r
co cm
In (1111 (a)
VO”
(al
Nl ‘311
Mn
(111
Fe (utl (al
cu
CII)
Ag (1)
TI (1) LO 0.8
0.6 0.4 0.2 01)
#
t L--l RF
lsg[gcw~~
..t
-0.6
0
0.6
Fig. I. Distribution of metal ion-thiocyanatc complexes bctwecn aqueous KSCN and anion exchange papers. Rp values VS. log [SCN-] on: (0) Whatman No. I ; ( U) Al581 ; (I) DE-81 ; and (a) SB-2. Bottom right: rcfcrcnce chart for tile values in the co-ordinates. (a) inclicates the USC of aqueous KSCN _1- 0.1 M I-ISCN as elucnt.
of the nature, and order of the stability constants, of thiocyanate complexes in aqueous solution’. Quite recently, a paper appeared on anion exchange studies (with Dowex I) At present we are investigating the Tl(SCN):;“and of Cd(SCN)f&-!,-‘”complexes”. Pb(SCN)f,;” systems (with Amberlite IRA+oo), and have obtained D values which fit the distribution curves calculated by using tabulated values of stability constants6 and the anion exchange theory0 satisfactorily. The determined D values of Tl(1) are in good accordance with those calculated from the Xp data (on 93-2) of Fig. I. As to (2) and (3), the employment of AE and DE exchangers in such a type of investigation obviously needs a profound knowledge of their properties and behaviour, which at present seems to be missing. On the other hand, the graphs XM VS. log a function of aqueous SCN-) for Fe(III), Co(II), 11~; a = activity (RM = log (I/RF %n(II), Cd(I1) on DE, and Ag(I), I-Ig( II) on AE and DE, fit fairly well to the calculated distribution curves. The same can be saicl about the log D vs. log a graphs we recently obtained for l?e(III), Ag(I), Zn(I1) and Hg(II), by measuring the distribution of the metal cations between AE and DE (powders) and aqueous KSCN, by means of column or distribution techniques, This work is still in progress. The finclings on Hg(I1) and Tl( I) are of special interest to our research pro’ gramme. We are studying organometal-halide and -pseudohalide complexes, which are generally rather labile in aqueous solution and may be successfully investigated by J.
Ch~omnfog.,
30 (1907)
G40-542
642
NOTES
about the influence anion exchange idle--12.The aim of the work is to get information of organic radicals, bound to the metal atom, on the tendency of the latter to coordinate, Anion exchange stability constants of the corresponding metal ion complexes are then needed, and the best comparison is obviously effected between values obtained with the same method. The reason why we are studying the cellulose exchangers is that it seems possible to employ AE and DE for anion exchange studies of arylmetal complexes. In fact, while the latter are adsorbed on the classical anion exchange resins by a mechanism probably different from anion exchanger”, their behaviour on AE and DE appears to he quite normal”J’t. The authors would like to acknowledge delle Ricerche.
CentjBo da’ Chimica delle Radiazioni e dei Radioelemmh’ de1 CNR, Padova (Italy)
4 j G 7 S 9 IO I I
12 13
14
Received J.
of the Consiglio
GIUSEPPE
Nazionale
RIZZARDI
CJ~rol?zalo~~~~~J~y, Elsevicr, knstcrda~n, 1957. Ckem, So&, 109 (1916) ,597. G. FARAGLIA, A. CASS~L AND R. BAIU~~~R~, PYOC. Jo~mades IJclZb~zes de S+wratiou Iwnddialc cl de Cltro~rzatogva~hie (IT1 J.I.S.I.C.).Ass. Greek Chcrn. Ed., hthcns, 1966, p. 271. G. BAGLIANO, L. OSSICINI AND M. LEDERER,J, C?wo?natog., 21 (1966) 471. L. G. SILL~N AND A. E. MARTELL, Slabilif~~ Cotnsla&s of Me/al-low Comq!hxes, Pul>l. No. 17, Chcm. Sot,, London, 1gG4. 12.BARBIERI, G. I-IERRERA GUADA AND G. RIZZAI
I E. LEDERER 2 J. C. PHILIP
3
the support
AND AND
M. A.
LEDERER, BRAMLEY,
April rst, 1567
Cltwomalog.,
30 (1gG7)
G40-642
J.