UO2(VI)- 8-hydroxoquinoline and UO2(VI)- 8-mercaptoquinoline complexing in nano-reactors of UO2[Fe(CN)6]-gelatin-immobilized matrix Текст научной статьи по специальности «Химические науки»

УДК 541.49 O. V. Mikhailov

UO2(VI)- 8-HYDROXOQUINOLINE AND UO2(VI)- 8-MERCAPTOQUINOLINE COMPLEXING IN NANO-REACTORS OF UO2[Fe(CN)e]-GELATIN-IMMOBILIZED MATRIX

Keywords: dioxouranyl(VI)hexacyanoferrate(II), gelatin-immobilized matrix, complexing, 8-

hydroxyquinoline, 8-mercaptoquinoline.

Complexing processes proceeding into nano-reactors of di-oxouranyl(VI)hexacyanoferrate(II) gelatin-immobilized matrices under their contact with water-alkaline (РН 12.0) solutions of 8-hydroxyquinoline, 5-chloro-8-hydroxyquinoline, 5,7-dichloro-8-hydroxyquinoline, 8-mercapto-quinoline, 5-chloro-8-mercaptoquinoline, 5,7-dichloro-8-mercaptoquinoline, 5-bromo-8-mercap-toquinoline and 5-thiomethyl-8-mercaptoquinoline, have been studied. It has been found that destruction of gelatin-immobilized (UO2)2[Fe(CN)6j up to uranium acid H2UO4 proceeding under influence of OH -ions, preceded of introduction of each of ligands indicated into inner coordination sphere of U(VI). It has been shown that in the course of complexing, in the systems U(VI)-8-hydroxyquinoline and U(VI)-5-chloro-8-hydroxyquinoline, coordination compounds of types UO2L(OH)(H2O), UO2L2 and UO2L2HL are formed, in the system U(VI)-5,7-dichloro-8-hydroxyquinoline, UO2L(OH)(H2O) and UO2L2 and in the systems U(VI)-8-mercaptoquinoline, U(VI)-5-chloro-8-mercaptoquinoline, U(VI)-5,7-dichloro-8-mercaptoquinoline, U(VI)-5-bromo-8-mercapto quinoline and UO2(VI)-5-thiomethyl-8-mercaptoquinoline, only complex UO2L2 is formed.

Ключевые слова: диоксоуранил(VI) гексацианоферрат(П), желатин-иммобилизованная матрица, комплексообразование, 8-гидроксихинолин, 8-меракптохинолин.

Изучены процессы комплексообразования, протекающие в нанореакторах диоксоуранил^^гексацианоферрат^ных желатин-иммобилизованных матриц при их контакте с водно-щелочными (рН 12.0) растворами 8-гидроксихинолина, 5-хлор-8-гидрокси-хинолина, 5,7-дихлор-8-гидроксихинолина,

8-меркаптохинолина, 5-хлор-8-меркапто-хинолина, 5,7-дихлор-8-

меркаптохинолина, 5-бром-8-меркаптохинолина and 5-тио-метил-8-

меркаптохинолина. Обнаружено, что при этом имеет место деструкция жела-тин-иммобилизованного (UO2)2[Fe(CN)eJ до урановой кислоты H2UO4, протекающая под воздействием OH -ионов и предшествующая вхождению каждого из указанных лигандов во внутреннюю координационную сферу U(VI). Показано, что в ходе комплексообазования в системах U(VI)-8-гидроксихинолин, и U(VI)-5-хлор-8-гидроксихинолин образуются координационные соединения типов UO2L(OH)(H2O), UO2L2 и UO2L2HL, в системе и^)-5,7-дихлор-8-гидроксихинолин - UO2L(OH)(H2O) и UO2L2 и в системах U(VI)-8-меркаптохинолин, U(VI)-5-хлор-8-меркап- тохинолин, U(VI)-5,7-дихлор-8-меркаптохи-нолин, U(VI)-5-бром-8-меркаптохинолин и U(VI)-5-тиометил-8-меркаптохинолин - только комплекс UO2L2.

Introduction

Complexing of uranium(VI) with 8-hydroxyquinoline, 8-mercaptoquinoline and their some derivatives in solution and solid phase were studied in the number of works, the generalizing knowledge about of which are presented in publications [1-6]. As was found in them, abovementioned organic ligands form with dioxouranium(VI) UO22+ coordination compounds of UO2L2 type where L" is singly deprotonated form of corresponding ligand; in the case of nonsubstituted 8-hydroxyquinoline, under rather ligand concentration in solution complex UO2L2HL in which L" - forms of ligand are bidentate and coordinated to U through nitrogen and oxygen atoms whereas HL form is monodentate and coordinated to U atom through only nitrogen atom, can be formed [2-4]. However, complexing in the binary systems containing U(VI)- nonsubstituted or substituted 8-hydroxyquinoline or 8-mercaptoquinoline proceeding into gelatin-immobilized matrices (GIM) was considered by investigators up to now. The summarizing data of our earlier works generalized in review [7] evidences that coordination compounds which are not formed at complexing in solution or solid phase, may be obtained in the course of complexing in such a specific conditions. Moreover, complexing process in the systems indicated above, and, first of all, in the system в системе U(VI)-8-hydroxyquinoline, may be used to obtain silverless photographic images having luminic properties [8]. The present paper is devoted to study of peculiarities of complexing processes proceeding between U(VI) and non-substituted or some substituted 8-hydroxyquinoline or 8-mercaptoquinoline into nano-reactors which are in di-oxouranyl(VI)hexacyanoferrate(II) gelatin-immobilized matrices [(UO2)2[Fe(CN)6]-GIM].

Experimental

The synthesis of dioxouranyl(VI)hexacyanoferrate(n) gelatin-immobilized GIM were carried out by using original technology elaborated by us which consisted in following. Besides, the synthesis of immobilized matrix systems consisting elemental silver (Ag-GIM), preceded obtaining of above special-purpose matrices. Ag-GIM prepared then treated in a solution containing hexa-cyanoferrate(III) anion and acetic complex of dioxouranyl(VI); besides, elemental silver containing in Ag-GIM was oxidized in water-soluble Ag(I) compound and was removed from matrix into solution indicated with simultaneous precipitation of dioxouranyl(VI)hexacyanoferrate(II) (UO2)2[Fe(CN)6] in polymer mass according to general equation (1)

2[UO2(CHsCOO)s] + Ag + [Fe(CN)6]3- ^ (UO2fe[Fe(CN)6] + Ag+ + 6CH3COO- (1)

In order to determine of composition of coordination compounds formed into metal-chelate GIM, we subjected corresponding matrices by treatment according to technology described in [9] and isolated from them immobilized substances in solid phase which then analyzed by using of various physic-chemical methods. For example, at treatment according to this technology of GIM obtained on general equation (1), the dark-brown substance having U2FeC6N6O4 composition coinciding with stoichiometric (UO2)2[Fe(CN)6] formula, can be isolated. (Found (%): U 63.5; Fe 7.2; С 9.8; N 11.3; О 8.2. Calculated for formula indicated (%): U 63.30; Fe 7.43; С 9.59; N 11.17; О 8.51). (UO2)2[Fe(CN)6]-GIM obtained were then treated with water solutions of 8-hydroxyquinoline, 5-chloro-8-hydroxyquinoline, 5,7-dichloro-8-hydroxyquinoline, 8-mercaptoquinoline, 5-chloro-8-mercaptoquinoline, 5,7-dichloro-8-mercaptoquinoline, 5-bromo-8-mercaptoquinoline and 5-thiomethyl-8-mercaptoquinoline having ligand concentrations in the range 5.0-10-6 -5.0-10-2 mol-dm-3 and рН= 12.0±0.1. A temperature of ligand solutions and GIM contacting with them, was (20.0+0.5)°С. A time of contact GIM/ligand solution (actually nothing but a dueration of complexing process) was varied from 1 to 10 min. After completing of the

complexing process, the gelatin layer containing U(VI) coordination compounds of the ligands indicated were washed with runner water for 15 min and dried at room temperature for 2-3 hours. The kinetics of complexing process was described by D= f(CF, Cl°, t) relationships where D is the absorbance of the metal-chelate GIM corresponding to initial concentration of (UO2)2[Fe(CN)6] in a GIM (CF, mol-dm"3), the concentration of corresponding ligand in the solution contacting with this GIM (Cl°, mol-dm"3) and the complexing process time (t, min). In order to determine stoichiometric coefficients in equations relating to elementary acts of complex-ing process, we used the coordinate sections [CF= const, varied CL°, argument t] and [CL°= const, varied t, argument CF] which were analyzed by a procedure described elsewhere [10].

MALDI TOF mass spectra of substances isolated from GIMs were obtained using a Dynamo (Fimigan) and 4-nitroaniline matrix at 500MHz frequency and 55.25 units of laser power. The transmitted light absorbances of metal-complex GIM studied (D) were measured with a Macbeth TD 504 photometer (Kodak, USA) in the 0.1-5.0 absorbance units range with an accuracy +2% (rel.). Electron absorption spectra of the GIM were recorded using Specord UV-VIS (Carl Zeiss, Germany) and PU-8710 (Philips, The Netherlands) spectrometers in the 400-800 nm range.

Results and discussion

5 3

At very low (<10" mol-dm" ) concentrations of each of ligands indicated above in the solution contacting with dioxouranyl(VI)hexacyanoferrate(n) GIM and t >4 min, in the all range of CF

"3

values studied (0.1-2.0 mol-dm" ), the colour of polymer mass changes from red-brown to yellow with lemon tinge that is accompanied with rather considerable lowering of D values. It is significant that such a result (moreover for shorter time) can be reached by treatment of (UO2)2[Fe(CN)6]"GIM with water solutions of NaOH or KOH having pH > 11. The analysis of D= f(CF, Cl°, t) dependences in coordinate sections indicated for above-mentioned (CF, CL°, t) range according to [10] evidences that complexing process proceeding in such conditions, does not accompany by addition although one ligand molecule to previous (UO2)2[Fe(CN)6], and, hence, the change of colour of polymer mass D should be connected with an ability of (UO2)2[Fe(CN)6] to destruction by OH- ions influence well-known from [11]. The products isolated from GIM obtained under (CF, CL°, t) indicated, have yellow colour and, according to chemical analysis data, are nothing but dihydrate of uranium acid H2UO4-2H2O. By taking into consideration this circumstance and, also, that coordination numbers equal to 6 and more are typical for UO22+ [2-4, 12], it can be asserted that in the each of systems studied, alkaline destruction of (UO2)2[Fe(CN)6] described by general equation (2) precedes of process of substitution of

CN"

-anions into inner sphere of dioxouranyl(VI) hexacyanoferrate(n) coordination polymer:

(UO2)2[Fe(CN)6] + 4 OH" + 4H2O^ 2UO2(OH)2(H2O)2 + [Fe(CN)6]4" (2)

Therefore, the gelatin-immobilized diaquadihydroxodioxouranyl(VI) seems to starting point for further reaction of U(VI) with each of ligands under examination here. This compound has considerably lower absorption in the visible spectrum region compared with (UO2)2[Fe(CN)6], and, that is why, the lowering of D values indicated above, is quite naturally. The range from t= 0 up to reaching of first minimum corresponds to this process on the D= f(CF, CL°, t) curves in the coordinate section [CF= const, varied CL°, argument t].

In the U(VI)-non-substituted 8-hydroxyquinoline system, D= f(CF, CL°, t) curves in coordinate sections [CF= const, varied CL°, argument t] and [CL°= const, varied t, argument CF] have extremely complex character with two and even more number of minimums and maximums.

This circumstance is evidence that a formation of several coordination compounds occurs in the course of complexing. So, at CF= 0.1-0.8 mol-dm"3 u CL°= 1.2-10"2 mol-dm"3 in the system under examination, in the range t<1 min slight increase of D values takes place, in the range 1 min <t < 2 min they decrease, in the range of t= 2-4 min they increase once again, then decrease (in the range 4 min <t < 6 min) and further slightly increase again. At CF = 0.1-0.3 mol-dm"3 and higher Cl° (2.5-10"2 mol-dm"3), in the range t < 3 min D values decrease, in the range 3 min < t < 6 min they increase and then decrease again whereas at CF > 0.3 mol-dm"3 they in general decrease monotonously. At still more ligand concentration in solution, D= f(CF, CL°, t) curves in coordinate section [CF= const, varied CL°, argument t] have one minimum, then, D values increase slowly; besides, at CF < 0.5 mol-dm"3 and rather large t value (specifically, 8 min at CF= 0.2 mol-dm"3) D values begin to decrease again, and in ligand solution contacting with GIM, UO22+ cation appears. The colour of polymeric layers of GIM changes in the course of complexing from brown to yellow. The computer-mathematical analysis of D= f(CF, CL°, t) curves of above binary system according to [10] evidences that step complexing accompanied by addition, at first, of one 8-hydroxyquinoline molecule, and, then, second and third one, occurs. The first of these processes dominates in the range of CF= 0.2-1.5 mol-dm"3, CL°= 2.0-10"3- 2.0-10"2 mol-dm"3, 2 min <t< 6 min, the third, at CF< 0.5 mol-dm"3, CL°> 10"1 mol-dm"3, t> 8 min, and the second, at the remaining (CF, CL°, t) of the range studied here. When gelatin layer of metalchelate GIM formed at CF< 1.0 mol-dm"3, Cl°~5.0-10"3 mol-dm"3 and t> 8 min, are destroyed by the procedure [9], yellowish-brown substance precipitates. According to chemical analysis data, it has the intrinsic composition UC18N2H12O4 which corresponds to UO2L2 formula where H2L is a 8-hydroxyquinoline (table 1). MALDI TOF mass-spectra of substance isolated from GIMs showed the availability of two molecular ions peak having molecular masses M = 450 c.u. and 559 c.u. These values are nearly to calculated ones for UO2L(OH)(H2O) and UO2L2 complex (449.15 and 558.26, respectively).

In the U(VI)-5-chloro-8-hydroxyquinoline system, D= f(CF, CL°, t) curves in in coordinate sections [CF= const, varied CL°, argument t] and [CL°= const, varied t, argument CF] have character similar to one for U(VI)-non-substituted 8-hydroxyquinoline system; among their number, at CF= 0.1-0.9 mol-dm"3 and CL°= 1.2-10"2 mol-dm"3, in the binary system indicated at t< 1,5 min slightly increase D values occurs, in the range of 1,5 min <t < 3 min - their lowering, at t= 3-5 min - their new growth, then, lowering again (in the range 5 min < t < 7 min) and further D values do not change practically. In the range of CF = 0.1-0.4 mol-dm"3, CL°= 2.5-10"2 mol-dm"3 and t < 4 min D values decrease, in the range of 4 min < t < 6 min they growth and further decrease again, although at CF > 0.4 mol-dm"3, monotonous decrease of D takes place. At still more CF, D= f(CF, Cl°, t) curves in coordinate section [CF= const, varied CL°, argument t] have one minimum; besides, at CF < 0.5 mol-dm"3 by beginning with rather large t value (specifically, 7 min at CF= 0.3 mol-dm"3) D values do not change practically. And, finally, at CF< 0.5 mol-dm"3, Cl°> 4.0-10"2 mol-dm"3 u t > 7 min, optical densities begin to decrease again once, and in ligand solution contacting with GIM, UO22+ cation is discovered. The colour of polymer layers of GIM in the course of complexing changes from brown to brownish-yellow. The computer-mathematical analysis of D= =f(CF, CL°, t) curves for system under examination in accordance with methodology [10] allows to conclude that step complexing accompanied by addition of one, two and three molecules of ligand indicated takes place. Besides, the first of these processes prevails in the range of CF= 0.3-1.8 mol-dm"3, CL°= 1.5-10"3- 2.5-10"2 mol-dm"3, 2 min <t< 6 min, the third, at CF< 0.3 mol-dm"3, CL°> 10"1 mol-dm"3 and t > 10 min, and the second, at the remaining (CF, Cl°, t) of the range studied here. When gelatin layer of metalchelate GIM formed at CF< 1.0

mol-dm"3, Cl°~5.0-10"3 mol-dm"3 and t> 8 min, are destroyed by the procedure [9], yellowish-brown substance precipitates. According to chemical analysis data, it has the intrinsic composition UC18N2H1oO4Cl2 which corresponds to UO2L2 formula (H2L- 5-chloro-8-hydroxyquinoline) (table 1). MALDI TOF mass-spectra of substance isolated from GIMs showed the availability of two molecular ions peak having molecular masses M = 482 c.u. and 625 c.u. that is nearly to calculated M values for UO2L(OH)(H2O) and UO2L2 complex (483.60 and 627.15, respectively).

In the U(VI)-5,7-dichloro-8-hydroxyquinoline system, the picture of curves D= f(CF, CL°,t) in coordinate section [CF= const, varied CL°, argument t] in comparison with ones for two other binary system considered, is more simple. Unlike U(VI)-8-hydroxyquinoline and U(VI)-5-chloro-8-hydroxyquinoline systems, where, at the whole, a tendency to decrease of D values in comparison with one for initial (UO2)2[Fe(CN)6], in the U(VI)-5,7-dichloro-8-hydroxyquinoline system at

"2 "3

rather high ligand concentration (6.0-10" mol-dm" ), monotonous increase of D values in the all range studied t>0 is observed. The colour of polymer layers of GIM in the course of complexing changes from brown to yellow-brown. The analysis of D= f(CF, CL°, t) curves for the above system according to [10] shows that an addition of one, and, then, two molecules of 5,7-dichloro-8-hydroxyquinoline occurs. The first of processes indicated prevails in the range of CF= 0.2-1.7 mol-dm"3, Cl°= 1.2-10"3- 1.5-10"2 mol-dm"3, 1 min <t< 3 min, and the second - at the remaining (CF, Cl°, t) of the range studied here. When gelatin layer of metalchelate GIM formed at CF< 0.5 mol-dm"3, Cl°~5.0-10"3 mol-dm"3 and t> 8 min, are destroyed by the procedure [9], yellow-brown substance which according to chemical analysis data has the intrinsic composition UC18N2H8O4Cl4 corresponding to UO2L2 formula (H2L is 5,7-dichloro-8-hydroxyquinoline) precipitates (Table 1). MALDI TOF mass-spectra of substance isolated from GIMs showed the availability of one molecular ions peak having molecular mass M = 519 c.u. and 697 c.u. It is nearly to M values for UO2L(OH)(H2O) and UO2L2 complex (518.04 and 696.11, respectively).

In the systems U(VI)- 8-mercaptoquinoline, U(VI)-5-chloro-8-mercaptoquinoline, U(VI)-5,7-dichloro-8-mercaptoquinoline, U(VI)-5-bromo-8-mercapto-quinoline and U(VI)-5-thiomethyl-8-mercaptoquinoline, the course of D= f(CF, CL°, t) relationships in coordinate section [CF= const, varied Cl°, argument t] as well as in coordinate section [CL°= const, varied t, argument CF] is of the same type. For the each of these systems at relatively small Cl° values with t growth, lowering of optical densities D at firstly and, then, monotonous increase of them, occurs. At CL° >2.0-10"2 mol-dm"3 and t >6 min, in the range of CF < 1.0 mol-dm"3 in the each of four systems indicated above, the compounds colouring polymer masses greenish-yellow or yellow-brown with various tinges, are accumulated in the GIM. The data of analysis of D= f(CF, Cl°, t) curves in coordinate sections indicated according to [10] evidences that an addition of two molecules of corresponding 8-mercaptoquinoline per one uranium atom takes place in the each of systems studied. When gelatin layer of metalchelate GIM formed at CF< 0.5 mol-dm"3, Cl°~5.0-10"3

"3

mol-dm" and t> 8 min, are destroyed by the procedure [9], the substances having yellow-green (non-substituted 8-mercaptoquinoline) or yellow-brown (5-chloro-8-mercaptoquinoline, 5,7-dichloro-8-mercaptoquinoline, 5-bromo-8-mercaptoquinoline, 5-thiomethyl-8-

mercaptoquinoline) colour, can be isolated. According to chemical analysis data, the each of them also has UO2L2 formula (H2L is corresponding 8-mercaptoquinoline) (table 1). MALDI TOF mass-spectra of substances isolated from these GIMs showed the availability of two molecular ion peaks having M = 464 c.u. and 590 c.u.; M = 535 c.u. and 729 c.u.; M = 544 c.u. and 749 c.u.; M = 510 c.u. and 684 c.u., respectively. They are nearly to theoretical calculated for UO2L(OH)(H2O) and UO2L2 complexes (465.21 and 590.38; 534.10 and 728.16; 544.11 and 748.17; 511.30 and 682.55, respectively).

Table 1 - Analytical data of U(VI) complexes with various 8-hydroxyquinolines and 8-mercaptoquinolines

Complex composition U C N H O S

U(VI)- non-substituted 8-hydroxyquinoline system

UO6H6 [UO2(OH)2(H2O)2] UC18N2H12O4 (UO2L2) 69.7 (70.00) 42.1 (42.64) 0.0 (0.00) 39.0 (38.73) 0.0 (0.00) 5.4 (5.02) 1.9 (176) 2.0 (2.15) 28.4 (28.24) 11.5 (11.46) 0.0 (0.00) 0.0 (0.00)

U(VI)- 5-chloro-8-hydroxyquinoline system

UO6H6 [UO2(OH)2(H2O)2] UC18N2H10O4CI2 (UO2L2) 70.4 (70.00) 38.3 (37.95) 0.0 (0.00) 34.1 (34.47) 0.0 (0.00) 4.4 (4.46) 1.6 (176) 1.8 (1.60) 28.0 (28.24) 9.9 (10.20) 0.0 (0.00) 0.0 (0.00)

U(VI)- 5,7-dichloro-8-hydroxyquinoline system

UO6H6 [UO2(OH)2(H2O)2] UC18N2H8O4CI4 (UO2L2) 70.2 (70.00) 33.9 (34.19) 0.0 (0.00) 31.5 (31.05) 0.0 (0.00) 3.8 (4.02) 1.9 (176) 1.3 (1.15) 27.9 (28.24) 9.4 (9.19) 0.0 (0.00) 0.0 (0.00)

U(VI)- non-substituted 8-mercaptoquinoline system

UO6H6 [UO2(OH)2(H2O)2] UC18N2H12O2S2 (UO2L2) 70.3 (70.00) 40.8 (40.33) 0.0 (0.00) 36.4 (36.63) 0.0 (0.00) 4.9 (4.75) 2.0 (176) 1.8 (2.03) 28.1 (28.24) 5.6 (5.42) 0.0 (0.00) 10.6 (10.84)

U(VI)- 5-chloro-8-mercaptoquinoline system

UO6H6 [UO2(OH)2(H2O)2] UC18N2H10O2S2CI2 (UO2L2) 69.6 (70.00) 35.8 (36.11) 0.0 (0.00) 33.0 (32.79) 0.0 (0.00) 4.4 (4.25) 1.9 (176) 1.6 (1.52) 28.2 (28.24) 5.0 (4.85) 0.0 (0.00) 9.5 (9.73)

U(VI)- 5,7-dichloro-8-mercaptoquinoline system

UO6H6 [UO2(OH)2(H2O)2] UC18N2H8O2S2CI4 (UO2L2) 69.9 (70.00) 33.0 (32.69) 0.0 (0.00) 30.0 (29.69) 0.0 (0.00) 3.6 (3.85) 2.0 (176) 0.9 (110) 28.5 (28.24) 4.3 (4.39) 0.0 (0.00) 8.6 (8.81)

U(VI)- 5-bromo-8-mercaptoquinoline system

UO6H6 [UO2(OH)2(H2O)2] UC18N2H1oO2S2Bf2 (UO2L2) 70.3 (70.00) 31.4 (31.82) 0.0 (0.00) 29.2 (28.89) 0.0 (0.00) 3.8 (3.74) 2.0 (176) 1.5 (1.34) 28.0 (28.24) 4.4 (4.28) 0.0 (0.00) 8.3 (8.57)

U(VI)- 5-thiomethyl-8-mercaptoquinoline system

UO6H6 [UO2(OH)2(H2O)2] UC20N2H16O2S4 (UO2L2) 70.2 (70.00) 35.1 (34.88) 0.0 (0.00) 35.3 (35.19) 0.0 (0.00) 3.9 (4.n) 2.0 (176) 2.1 (2.34) 28.1 (28.24) 4.9 (4.66) 0.0 (0.00) 18.3 (18.79)

By taking into account the all foregoing, it can be postulated that in the binary systems under examination, the following processes on the level with alkaline destruction of dioxouranyl (Vl)hexacyanoferrate(II) occur:

In the U(VI)- non-substituted 8-hydroxyquinoline system:

OH

UO2(OH)2(H2O)2 +

O

OH

I U

n^II*soh2

O 2

+ 2 H21

(3)

O

OH

1 U

iA\

N' II OH2

O 2

O

U

і/

N.

A\4o-^

O

+ 2КЇ (4)

O

OH

.N

U'

N^ll O

+ OH --------►

N

O\

^N-

O + H21 (5) O_

In the U(VI)- 5-chloro-8-hydroxyquinoline system:

OH

.N

O

UO2(OH)2(H2O)2 +

OH

Cl-

Cl

Nx II OH

+ 2 H21

O

(6)

O

OH

OH

.N

Cl

U +

N' II OH2 I

O 2 I

O Cl

Cl

N

У „ ,

/"її No"^

+ 2 H21 (7)

+

/

O

O\IyN

U

OH

Cl 1 .N

Cl

N

A

O

+ OH -------►

O

O\IyN' .

U*-O +H2I (8)

Cl

fl\

JJ .N

O

V \\ r^

Cl

In the UO2(VI)- 5,7-dichloro-8-hydroxyquinoline system:

Cl

OH

Cl A N

UO2(OH)2(H2O)2 +

O

O II OH

N

Nil

,/*||\ O

+ 2 H2 I

(9)

OH

Cl

O

O II OH Cl

OH

Cl

'\lly

.N

Cl

U +

y'llN

Nx II OH2 |

O 2 I

O

Cl

Cl

O\ll/N-U

N^ll N'SO'

O Cl

+ 2H21 (10)

In the U(VI)- non-substituted 8-mercaptoquinoline (R1" H, R2" H), U(VI)- 5-chloro-8- mercap-toquinoline (R1" Cl, R2" H), U(VI)- 5,7-dichloro-8-mercaptoquinoline (R1"Cl, R2" Cl), U(VI)- 5-bromo-8-mercaptoquinoline (R1" Br, R2" H) and U(VI)-5-thiomethyl-8-mercaptoquinoline (R1" SCH3, R2" H) systems:

SH

R2 ^ .N

R,

UO2(OH)2(H2O)2 +

O

s. 11 ,OH

R

R

+ 2 H21

(11)

R

2O

^l/OHR2 U +

SH

1 II O 2

R O II

NI^N

U

n^IIN-

O

+ 2 H2 T (12)

R

+

By taking into consideration the totality of processes (2) and (3)-(5), (9)-(10), it may be to understand peculiar course of D= f(CF, Cl°, t) kinetic curves with rather well-defined minimums and maximums. The point is that product of alkaline destruction of dioxouranyl(VI) hexacyanofer-rate(II), namely (UO2)(OH)2(H2O)2, absorbs in the visible spectrum region considerably fainter than initial (UO2)2[Fe(CN)6], and, that is why, at increase of its molar part in the system in first moment of process when complexing between U(VI) and some of ligand studied is practically absent, the optical densities D diminish. Subsequently, when in the systems studied UO2L(OH)(H2O) coordination compounds absorption of which is more considerable in comparison with (UO2)2[Fe(CN)6], the optical densities begin to increase; however, when in nanoreactors of polymer mass UO2L2 chelates begin to be accumulated, D values decrease again because chelate having 1:2 composition absorbs fainter than chelate having 1:1 composition. Under rather large ligand concentrations in solution, the stage of formation of UO2L(OH)(H2O) compounds can be absent, and maximums on D= f(CF, CL°, t) kinetic curves in coordinate section [CF= const, varied CL°, argument t] must be not observed already. And namely this occurs indeed.

A series of experiments was used to study complexing of the dioxouranyl(VI) -8- hy-droxyquinoline and dioxouranyl(VI) -8-mercaptoquinoline binary system under examination with samples of (UO2)2[Fe(CN)6]-GIM prepared from different types of gelatin. These experiments indicated that the complexing process in each of these system is independent of the gelatin type. Thus, we can state that the gelatin is not acting as a ligand in the complexing process.

References

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2. Кукушкин Ю.Н. Химия координационных соединений. Москва, Высшая Школа, 1985. С. 82-84.

3. Drew M. G. В. Progr. Inorg. Chem., 1977. V. 23, N 1. P. 65-88.

4. Drew М. G. В. Coord. Chem. Rev., 1977. V. 24, N 2. P. 179-203.

5. Виноградов А.В., Елинсон С.В. Оксихинолин. Москва, Наука, 1979.

6. Банковский Ю.А. Химия внутрикомплексных соединений 8-меркаптохинолина и его производных. Рига, Zinatne, 1978.

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9.Mikhailov О.У. Indian J. Chem., 1991. V. 30A, N 3.252-254.

10.Mikhailov O.V. Russ. J. Coord. Chem., 1992. V. 18, N 12. P. 1008-1017.

11. Тананаев И.В., Сейфер Г.Б., Харитонов Ю.А., Кузнецов В.Г., Корольков А.П. Химия ферроцианидов. Москва, Наука, 1971.

12. Cotton F.A., Wilkinson G.B. Advanced Inorganic Chemistry. 5th Edition. Wiley, 1990.

13. Lever A.B.P. Inorganic Electronic Spectroscopy (second edition). Elsevier, Amsterdam- Oxford- New York- Tokyo, 1987.

© O. V. Mikhailov - д-р хим. наук, проф. каф. аналитической химии, сертификации и менеджмента качества КГТУ. E-mail: [email protected].