Spectroscopic studies on the uranyl complexes with 1,2-disubstituted benzenes

Spectroscopic studies on the uranyl complexes with 1,2-disubstituted benzenes

J. inorg, null. Chem., 1974, Vol. 36, pp. 2015 2021. Pergamon Press. Printed in Great Britain SPECTROSCOPIC STUDIES ON THE URANYL COMPLEXES WITH 1,2-...

515KB Sizes 0 Downloads 109 Views

J. inorg, null. Chem., 1974, Vol. 36, pp. 2015 2021. Pergamon Press. Printed in Great Britain

SPECTROSCOPIC STUDIES ON THE URANYL COMPLEXES WITH 1,2-DISUBSTITUTED BENZENES BONG-IL KIM, CHIE MIYAKE and SHOSUKE IMOTO Department of Nuclear Engineering, Faculty of Engineering, Osaka University, Suita, Osaka. Japan (First received 24 September 1973: in rerisedji~rm 26 Norember 1973}

Abstract--Uranyl complexes with a series of 1,2-disubstituted benzenes, such as phthalic acid (H2ph), salicylic acid (Hsal), pyrocatechol (H2pcl, anthranilic acid (Hant), o-aminophenol (amph), and o-phenylenediamine (phen), have been prepared and studied by i.r., electronic and NMR spectroscopy. Characteristic i.r. stretching frequencies (4000-200 cm-~) are reported for each complex. One or two new strong bands are observed in the region of 340 500 nm in all the complexes except uranyl phthalate, which are considered to be due to the charge transfer transition from the prr orbital of the donor atoms to 51- and/or 6d-orbitals of uranium. Characteristic proton magnetic resonance spectra of the complexes are also reported and discussed in relation to the magnetic anisotropy of the uranyl ion and to 1he drainage of electron density from the donor atom to the metal.

INTRODUCTION TRANSITION metal[i-3] and rare earth metal[4] complexes with a series of 1,2-disubstituted benzenes, such as phthalic acid (Hzph), salicylic acid (Hsal), pyrocatechol (Hzpc), anthranilic acid (Hant), o-aminophenol (amph) and o-phenylenediamine (phen), have been studied by i.r. and electronic spectroscopy and X-ray analysis. On the uranyl complexes (except uranyl salicylate[5,6]) with these ligands, however, only a few studies have been made. The uranyl ion, U O ,2+, is peculiar in its structure and its coordination behavior. The uranium(VI) atom in uranyl compounds is usually in six-, seven- or eightcoordination[7]. The two uranyl oxygen atoms are closely held (1-6-1-9 A) in a group which is approximately linear[8-11], whilst the four, five or six donor atoms of ligands are at greater distances (2-3 A) and lie approximately in the equatorial plane. Triatomic uranyl ion ( O - U - O ) 2. has four fundamental vibrations; (1) non-degenerate symmetric stretching vibration[8-10, 12], i~1, normally i.r. forbidden, occurring in the range 900-800 c m - 1 ; (2) nondegenerate asymmetric stretching vibration, v3, which is i.r. active and occurs at 1000-850cm -1 ;. and (3) doubly degenerate O U O bending vibration, v2, i.r. active and appearing below 300 c m - 1. McGlynn et al.[8] found that for a series of complexes formulated UO2L2(NO3) 2 the uranyl asymmetric stretching vibration shifted to lower frequencies in order of increasing field of the spectrochemical series of ligands. However, Day and Venanzi[13] did not find any regular relation between the band position and ligand in U O 2 X 2 L 2 (X = C1, Br or I ; L = Ph3PO or Et3PO}, and stated that vibrational interaction 2015

proposed by Jones[10] should also be taken into consideration and if both factors are to apply, the resulting frequencies would be unpredictable. From a comparison of a large number of different uranyl complexesE14,15], it becomes immediately obvious that their electronic spectra exhibit a rather remarkable similarity[16, 17]. Indeed, almost invariably two or three low intensity band systems are found between 340 and 500 nm, and these systems are characterized by a well-defined vibronic structure. Equatorial ligation has only a relatively minor influence on the spectrum[17]. However, it is also reported that in some uranyl complexes with Schiff bases[18] or other ligands[17] that contain N or S as the coordinating atom the corresponding spectra are generally characterized by much higher intensity and by complete lack of vibrational structure. Detailed analysis for this has not been made, though it is considered to be due to metal ligand charge transfer transition. Recently, several investigations have been made on the proton magnetic resonance spectra of the uranyl complexes. Siddal and Prohaska[19] proposed that the chemical shifts for the protons in the uranyl nitrate adducts of methylenediphosphonates could be accounted for by considering the magnetic anisotropy of the uranyl group as the most important factor. But Subramanian et aLl20, 21] proposed that complexation in UO2L2 X (L = fl-diketones; X = pyridine N-oxide or its para-derivativesl would cause deshielding of protons due to the "drainage" of electron density from the oxygen to the metal ion. Now, it is desirable to study the uranyl complexes systematically using a series of ligands. As for the uranyl complexes with 1,2-disubstituted benzenes, UO2{ph) E22], UO2{pc)H20[221, UO2{ant)2.4H 20{ 231

BONG-IL KIM, CHIE MIYAKEand SHOSUKEIMOTO

2016

sulfoxide (D6-DMSO) with tetramethylsilane (TMS) as the internal standard.

a n d UO2(sal)2 . n ( H 2 0 ) (n = 0, 2, 3, 5, 9)[5, 6, 23] were isolated, but the structures a n d spectroscopic (i.r., electronic a n d N M R spectra) properties of these substances have scarcely been studied except X-ray structural and i.r. spectral studies o n UO2(sal) 2 . n i l 2 0 [5, 6, 23]. In this paper we report the preparations a n d some discussions a b o u t i.r. (4000-200 c m - 1), electronic (210600 nm) a n d N M R spectral features of seven uranyl complexes [UO2(ph). H 2 0 , U O 2 ( s a l ) 2 . 2 H 2 0 , UOz( p c ) . 3 H 2 0 , U O 2 ( a n t ) 2 ( H a n t ) . 2HzO, UO2(ant)2, UO2(amph)2(NO3)2, a n d UO2(phen)2(NO3)z. H20].

Preparation of uranyl complexes

EXPERIMENTAL

Reagents Analytical grade reagents of uranyl nitrate hexahydrate, uranyl acetate dihydrate, phthalic acid, salicylic acid, pyrocatechol and anthranilic acid were used. o-Aminophenol and o-phenylenediamine were purified by recrystallization from acetone. (All the reagents from Nakarai Chemical Co.)

Analysis Carbon, hydrogen and nitrogen were determined by gravimetric chemical analysis. Uranium was determined by the ammonia method[24].

InJrared spectra I.R. spectra in the rock salt region were recorded on a Hitachi 225 spectrophotometer for Nujol and hexachlorobutadiene mulls supported between sodium chloride plates. Far i.r. spectra were recorded on a Hitachi EPI-L spectrophotometer for Nujol mulls supported between cesium iodide plates.

Electronic spectra U.V. and visible spectra were measured on a Hitachi EPS-3T spectrophotometer using ethanol or dimethylsulfoxide (DMSO) as solvent.

Proton magnetic resonance spectra These were measured on a JEC PS-100 high resolution spectrophotometer at 100 MHz in hexadeutero-dimethyl-

Mono(phthalato)dioxouranium(VI) monohydrate, [UO2(CsH404) ] . H20. Uranyl acetate dihydrate and phthalic acid (molar ratio 1:2) were dissolved in ethanol. The yellow solution was refluxed until yellow solids precipitated. The yellow solids were filtered and washed with ethanol and acetone several times and then suspended in hot water with stirring. The product obtained by the successive filtrations was dried in vacuo. Diaquo bis(salicylato)dioxouranium(Vl), U O 2 ( C 7 H 5 0 3 ) 2 . 2H20. Uranyl acetate dihydrate and salicylic acid (molar ratio 1:2) were dissolved in ethanol. After refluxing, the solution was concentrated by evaporating in vacuo. Water was added with stirring to this saturated solution until orange solids precipitated. This process involving refluxing was done twice. The precipitates obtained by filtration were washed with water and dried in vacuo. Triaquo mono(pyrocatecholato)dioxouranium(VI), UO 2(C6H,,O2). 3H20. Pyrocatechol (1.65 g) in ethanol (10 ml) was added with stirring at 60°C to the ethanol solution (30 ml) of uranyl acetate dihydrate (2.12 g). After a few hours, a brown adduct precipitated. The adduct was washed with ethanol several times. This adduct was not purified because of its low solubility in ordinary solvents. Bis(anthranilato)mono(anthranilic acid)dioxouranium(VI) dihydrate, [UO2(CTH6NO2)2(CvHTNO2)]. 2H20. Uranyl nitrate hexahydrate and anthranilic acid (molar ratio 1:3) was dissolved in diethylether. A yellow precipitate appeared with evaporation. This adduct was reprecipitated from ethanol by adding water. The precipitate obtained by filtration was dried in vacuo. Bis(anthranilato)dioxouranium(VI), UO2(CTH6NO2) 2 . This was obtained by heating [UOE(ant)2(Hant)]. 2H20 at 140°C in nitrogen atmosphere. Dinitrato bis(o-aminophenolato)dioxouranium(VI), UO 2(C6HTNO2)2(NO3)2 . Uranyl nitrate hexahydrate and oaminophenol (molar ratio 1:2) were dissolved in diethyl ether. This solution was refluxed until brown solids precipitated. It was recrystallized from ethanol. The adduct obtained by filtration was dried in vacuo. Dinitrato bis(o-phenylenediaminato)dioxouranium(VI) monohydrate, [UO2(C6HaN2)z(NO3)2]. H20. This was prepared by the same method as in the case of UO2(amph)2(NO3)2. The analytical data of the complexes prepared are given in Table 1.

Table 1. Analysis, color and symbol of the complexes Found ('!o) Complex UO/(ph). H 2 0 UOz(sal)z. 2H20 UO2(pc). 3H20 UOE(ant)z(Hant). 2H20 UOz(ant)2 UO2(amph)2(NO3) 2 UOz(phen)2(NO3)z. HzO

Color Yellow Pink Brown Yellow Green Brown Brown

Calc (!'0)

Symbol (A) (B) (C) (D) (D') (E) (F)

U

C

H

52.58 40-34 54-60 33.63 44.69 37.57 37-21

21.48 28.80 16.14 34.93 31.18 23.62 23-98

1.11 2.10 1.64 3.24 2.21 2.40 2.94

N

U

C

H

N

5.94 5.25 8.99 13.02

52.65 41-03 55.09 33.29 43.91 38.89 37.90

21.48 28.97 16.67 35.24 31.00 23.53 22.93

1-33 2.41 2.31 3.22 2.21 2.29 2-87

5,87 5.17 9.15 13-38

2017

Uranyl complexes with 1,2-disubstituted benzenes RESULTS A N D D I S C U S S I O N

h!fi'ared spectra I.R. spectral data of the uranyl complexes studied here are given in Table 2. The NH2 stretching vibration in aromatic amine[l, 2] appears as two or three sharp bands at about 3400cm- ~, In the complexes with the ligands containing NHz group the corresponding stretching bands shift about 100 c m - ~ negatively. The decrease in the frequency of the NH2 stretching vibration seems to be an evidence of nitrogen-metal coordination. Additional bands appeared at about 2600 c m - ~ in (D} can be assigned as the -NH~ stretching vibration[25], showing the presence of uncoordinated NH3~ group. This uncoordinated NH~- group probably combines with the neighboring carboxylate oxygen through a hydro-

%

gen bond, as the

/

NH + group does in UOi{C9H6NO)2

• {CgH7NO)I26, 27]. Hence, in (D) the uranyl ion is expected to be coordinated by five atoms in the equatorial plane two nitrogens from two amino

groups and three oxygens from three carboxylate groups (discussed latter). The O H (phenol) stretching vibrations in (B) and (E) shifts also about 100 cm-~ negatively relative to their positions, in the free ligands, thus showing that the O H (phenol) group coordinates to uranium• The O H {watert stretching vibration and the H O H bending vibration appear in all the complexes except (D') and (E), but water molecules seem to coordinate directly to uranium only in (B) and (C), where the O H (water) stretching vibration appears at lower wavenumbers, 3350 3150 cm An aromatic carboxyl group[2] in a free ligand is characterized by a strong absorption band at about 1670 c m - ' due to the C = O stretching vibration• In the complexes with the ligand containing carboxyl group the corresponding band is not observed, but two new strong bands are observed at about 1500 cm ~ and 1400cm -1, which are assigned as V,~y,,,(COO) and Vsym(COO)[2 ], respectively. Since these bands appear in (D) at nearly the same positions of 1500cm 1 and 1416cm -~ as those of sodium anthranilate[2~, it is

Table 2. Partial i.r. spectral data of the complexes {all values in cm ~1 Assignment

(A)

(B)

{C}

i D)

{D'I

qE}

(F)

Ligand mo&',s vNH, v:,,rmCOO V,~m('OO vOH(phenoH

1505(s) 1395(S}

vOH(water}

3589(s) 3521(m) 1650(m, sh}

6ttOH

3435(m1" 3336(m1+ 2600(m, b}+ 1500(s} 1416(S)

1524(s} 1405(S) 3228(m1

3480(m) 3375(m) 3321(m) 1497{s1 1396(S)

3210(m) 3130{m)

34201m} 3345(m~ aZ50nn)

3040(m} 2940(m }

3335(s}

3250(s) 31501s} 1635(m,sh}

1648(m)

3550(m.b)

3450(m, b }

1635(m,sh)

16471nl. sh)

110 2 mod{,,~

I: W() ~,~o,I!O ~~OUO .....

956(S)

946(S)

916(S1 820(w} 253(s) 243(s)

816{w}

250(s}

251(s}

91{RS)

9171S)

8681s)

253(s} 245(s)

257{s} 248(s)

2561s1 2531s1

9151sl 815lw, shl 252(s~

vl~O

(metal nitrate) {metal-carboxylate}

222(m}

(metal phenol) {metal water) vl IN

230(w, sh} 225(w, sh} 402(s) 258(s)

2221m}

228(w, sh)

3261ml

316(m}

Vibrational modes of the nitrate group

J.I.N.C•, VoL 36, No. 9--G

238{m) 225(m)

343(m1

387(m. b}

344(m) 277(m~

* s, strong; m, medium: w, weak: b, broad: sh, shoulder. ~ NH~ stretching vibration.

(E) (F)

2371ml

171

"92

1508 1500

1039 1034

V3

747 757

V4.

1280 1240

V5

I' 6

712 721

809 823

2018

BONG-1L KIM, CHIE MIYAKE and SHOSUKE IMOTO

considered that the carboxyl group in the complexes bonds to uranium electrostatically. The nitrate group in (E) and (F) shows the vibrational modes of C2v symmetry[28,29], which suggests that the nitrate group coordinates to uranium, not existing as a free ion. UO2 vibrational modes. In addition to the ligand vibrational modes, i.r. spectra of all the complexes studied in the rock salt region show strong absorption bands at 960-860 cm- 1and weak ones at 850-800 cm- ~. These bands are assigned as v3 and v1 of the uranyl ion, respectively. The assignment of vI is a little doubtful because the ligand vibrational modes also appear in this region. It is well known that the frequency of v3 decreases with the basicity of the equatorial ligand due to the electrostatic repulsion between the nonbonding or weakly n-bonding electrons of the uranyl oxygen and the L-M charge transfer electrons[8]. The frequency of v3 of the complexes studied here decreases in the order (A) > (B) > (C) ~ (F) > (D) > (E), which seems consistent with that of the basicities of the ligands, except (F). The slightly higher frequency of v3 in (F), which contains the most basic ligand, suggests that the coupling[10] between v3 and ~OUL, the bending vibrations of the bonds to the equatorial ligands, might also operate. The OUO bending vibration occurs at 260-240 cm- 1 in the far i.r. spectra of these complexes, which also appears in U O 2 ( N O 3 ) 2 . 6 H 2 0 , U O 2 X 2 L 2 (X = C1, Br, NO3 or SCN; L = Ph3PO or Ph3AsO)[14] and UO2X2L 3 (X = NO 3 or SCN; L = pyridine N-oxide or its derivatives)j15].

bands appearing in the region 400-300 cm-1 in (D), (D'), (E) and (F) are thus assigned to vUN.

Electronic spectra The electronic spectra of many uranyl complexes generally exhibit band systems characterized by a welldefined vibronic structure[16] between 340-500nm. From about 340nm towards the vacuum u.v.. one observes a high intensity and structureless continuum. However, it is known that the ligation in the equatorial plane has only a relatively minor influence on the spectrum[17] and the electronic spectra of complexes in the visible region is essentially determined by the triatomic UO 2+ entity. Electronic spectral data for the uranyl complexes studied here are given in Fig. 1, which shows that one or two new bands appear between 340-500 nm in all the complexes except (A), but in (C) two shoulders instead of distinct bands seem to appear at about 340 nm and 460 nm. These new bands are characterized by much higher intensity and by complete lack of vibrational structures and are not observed in the case that only nitrate and/or water coordinate to uranium[16, 17]. Also, these are not observed in (A), where the coordinating groups are carboxylate, which coordinates to uranium electrostatically, but are observed in the other complexes, where the coordinating ones are amino and/or hydroxy (phenol) groups, which are of relatively strong basicity.

Uranium-oxygen (of the equatorial ligand) stretching Jrequency. Unequivocal assignment of the uraniumoxygen stretching modes in the CsBr region was difficult owing to the interaction of vMO modes with vibrations within the ligands. However, based on a comparison of the spectra of related complexes and corresponding free ligands, some empirical band assignments have been made. In the complexes studied here there are four kinds of metal-oxygen (of the nitrate, carboxylate, phenol and water) stretching modes. In all the complexes except (C) new absorption bands (not observed in the free ligands) are observed in the region 240-220 cm- 1. In (E) and (F) these bands are assigned as the U O (nitrate) stretching, vibration from a comparison with that of UO2Ln(NO3)2 (n = 2 or 3; L = pyridine N-oxide or its derivatives)[15]. In UO2{CH3CO2) 2 . 2H20 strong bands observed at about 230 cm- 1 in the present work are considered to be due to vUO (carboxylate), because the band of vUO (water) seems to appear in the higher region[30]. The other new bands observed at 402cm -~ and 258 cm- 1 in (B) and at 344 cm- 1 and 277 cm- 1 in (C) are assigned as vUO (phenol and water), but these are not distinguished from each other at present. Uranium nitrogen stretching .[requency. The uranium-nitrogen stretching vibration is assigned by eliminating 6OUO and vUO from all the new bands observed in the complexes in the CsBr region. The

5

\

\,/

I

i

300

400 ~,

500

nm

Fig. l. Electronic spectra of the uranyl complexes. , (A} in DMSO; -.-, (B) in ethanol; - - - , (C) in DMSO; .- , (D) in ethanol; . . . . . , (D) in ethanol; . . . . . . , (E) in ethanol; ...... , (F) in ethanol.

2019

Uranyl complexes with 1,2-disubstituted benzenes Hence, these new bands are supposed to occur by the charge transfer transition from the pn orbital of the donor atoms in the equatorial ligands to 5.1'- and/or 6d-orbitals of uranium. Proton magnetic resonance spectra

Characteristic proton magnetic resonance frequencies in the uranyl complexes and in the free ligands are given in Table 3. The chemical shifts observed for the protons in the uranyl complexes can be accounted for by considering the magnetic anisotropy[19, 31, 32] of the uranyl group and the deshielding due to the drainage of electron density[20, 21] from the donor atoms to the metal as the most important factors. Pople et al. [33] gave the equation for the chemical shifts to be expected for protons in the neighborhood of an anisotropic field such as uranyl ion Aom = AZatomic(1- 3 COS2 7)/3R 3

(1)

where Axatomic = Zatomic(parallel to axis) - Zatomic(perpendicular to axis), R is the distance of the proton from

the anisotropic atom (or group in this case), and ;, is the angle between a line joining the proton to the center of the anisotropic group and the axis of symmetry of the anisotropic group. Phenyl ring protons. In the 1,2-disubstituted benzenes the chemical shifts for phenyl ring protons vary due to electron withdrawing/donating substituents at the X and Ypositions. Ha Hb

"

Ha In phthalic acid (X = Y= COOH, electron withdrawing group), pyrocatechol (X = Y= OH, electron donating group) and o-phenylenediamine (X = Y= NH 2, electron donating group), the phenyl ring protons in each molecule are nearly equivalent and the resonance peaks of these protons appear at 2-39, 3.32 and 3.58 ppm, respectively. This shows that the drainage of electron density from phenyl ring to the substituents

Table 3. Characteristic proton magnetic resonance frequencies in the free ligands and in the uranyl complexes in D6-DMSO Chemical shift (r : ppm) Phenyl ring protons Hzph (A) Hsal (B) H2pc (C) Hant (D) (D') amph (E) phen (F)

Other protons

2.39(HI,2.3.4) 2-19(H1,4)2.61(H2,3) 2-20(H1)2.49(H3) 3-10(H2.4) 1.88(H02.56(H3) 3.09(Hz,4) 3"32(H1,2,3.4) Insufficiently soluble in D6-DMSO 2.27(H1) 2.78(H3) 3.22(H4) 3.54(H2) 2-77(HL3) 3.28(H2,4) 2.77(HI,3)3.16(H2,4) 3.52(H1.2,3,4) 3.40(Hi,4)3.53(H2.3) 3.58(Ht.2,3,4) 2.08(Ht,4)2.40(H2,3)

- 1-80(OH)*

1.40(NHJ ) 1.76(NHz) 2.28(NH~) 1.64(NH2) 1,051OH)* 5.56(NH2) 1,04(OH)* 5.16(NH2) 5.65(NH 2) 308, 3-46(NH:)

* OH group of phenol H1

COOH

FI1

H

H2

H2

H3

COOH

H4 H2Ph HI H 2 ~ H3 ~ . / H4 Hant

H3

OH

H 3" " " - / " ~

Ha Hsal COOH "~NH z

H~ H 2 ~ H3~""~NH H4 amph

OH

H4 Hzpc Hl H 2 ~

OH 2

''NH2

H3~....-,/~NH 2 H4 phen

2020

BONG-IL KIM, CHIE MIYAKEand SHOSUKEIMOTO

or from the latter to the former brings about downfield or upfield shift equally for all phenyl ring protons without any marked difference of the chemical shifts between H~ and Hb protons. Complexation causes the deshielding of both H~ and H b protons due to the anisotropic field of uranyl group and the change of the drainage of electron density from the donor atom to the metal. However, it is reasonable that VAB, the difference of the chemical shifts between Ha and H b protons, observed for (A) and (F), is attributed to the effect of the anisotropic field of the uranyl ion, because H~ and Hb protons seem to remain equivalent even if some change of the drainage of electron density between ligand and metal occurs by complexation. If it is assumed that the complexes have the highest symmetric structures with the distance between carboxylate oxygen and uranium of 2.9 A and that between the nitrogen of the amino group and uranium of 2.7 A, VABin (A) and (F) can be calculated to be 0.41 and 0.31 ppm, respectively, by substituting AZ = - 2 . 7 4 x 10-28119] and 7 = n / 2 into Eqn (1). The values of VABcalculated consist with the values of 0.42 and 0.32 ppm observed in (A) and (F), respectively, supporting our assumption that VAB in the uranyl complexes should be caused by the anisotropic field of uranyl ion. This argument is different from Subramanian and Manchanda's[21], who explained the VA~ of the protons of pyridine N-oxide or its p a r a derivatives in UO2L2X (L = fl-diketones; X = pyridine N-oxide or its p a r a - d e r i v a t i v e s ) in the term of only deshielding effect due to the drainage of electron density from the pyridine N-oxide oxygen to the metal. Salicylic acid and anthranilic acid have both an electron-withdrawing C O O H group and an electrondonating O H or N H 2 group and the four phenyl ring protons resonate at three or four different frequencies. In these case complexation also gives rise to both the anisotropic field effect of the uranyl ion, Act,,, and the shielding effect caused by the drainage of electron

density between ligand and metal, A a d. The Aam'S were calculated by the same way in the case of (A) and (F), assuming that the distance between carboxylate oxygen and uranium to be 2.5 ~ 3.0 A and that between phenol oxygen or nitrogen of amino group and uranium to be 2.0 ~ 2.5 A. The values of r~,, the difference between the shift observed and Aam thus estimated, were then compared with the corresponding shift of free ligand, r L (Table 4). As shown in Table 4, the value of Aad( = ~ - rL) increases from H~ to H4 for (B), suggesting that back donation from metal to ligand occurs through the covalent bond U-O(phenol), not through the electrostatic bond U - O (carboxylate). The back donation also seems to operate in (D), but some complicated mechanism would hinder the monotonous increase of Ao"d from H~ to H4. N H 2 g r o u p p r o t o n s . In (E) and (F), N H 2 group protons are observed to be deshielded by about 0.36 and 2.57 ppm, respectively, due to the drainage of electron density from the nitrogen atom to the metal. In free anthranilic acid, amino group protons give a singlet and broad resonance signal at 1.40 ppm, which seems to have shifted downfield due to the intramolecular hydrogen b o n d [ 3 4 ] , - N H ~ - . . . - O O C , in D 6 - D M S O . However, in (D) two resonance peaks appear at 1.76 and 2.28 ppm and are assigned as ZNH2 and ZNn+ respectively, from the integral curve. The existence of the two kinds of amines supports the structure proposed by us from i.r. spectra. As expected, the resonance bands corresponding to rNn; is not observed in (D'). ,

3'

.

,

CONCLUSION The O U O 260cm -1 and ligation. New strong 34(~500nm in

bending vibration appears at 240shows minor change by equatorial bands are observed in the region the uranyl complexes with relatively

Table 4. Chemical shifts of phenyl ring protons in (B) and (Dt due to both magnetic anisotropy of uranyl ion and drainage of electron density between ligand and metal (B)

~c

Hl H2 Ha

1"88 3-09 2.56 3.09

(D)

rc

H1 H2

2-77 3.28 2.77 3-28

H3

H3

H4

Aam

-0'29 -0-19 -0.24 -0.65

~ ~ ~ ~

¢c = Zc - Aam

-0"38 -0.23 -0.32 -1.00

Aam

-0.29 -0.19 -0.24 -0-65

All values in ppm.

~ ~ ~ ~

2-17 ~ 3.28 ~ 2-80 ~ 3.74 ~

2'26 3-32 2.88 4-09

"c'c = ZC -- Aam

-0.38 -0.23 -0.32 - 1.00

3.06 ~ 3.47 ~ 3.01 ~ 3-93 ~

3.15 3.51 3.09 4.28

Zl.

2"20 3-10 2.49 3.10

"~L

2.27 3.54 2.78 3.22

Aft a = Z'c - z L

-0'03 0.18 0.31 0.64

~ ~ ~ ~

0.06 0.22 0.39 0.99

A O d = "[IC - - TL

0.79 ~ -0.07 ~ 0-23 ~ 0-71 ~

0.88 -0.03 0.31 1.06

Uranyl complexes with 1,2-disubstituted benzenes

strong basic ligand, which are considered to be due to the charge transfer transition from the pTt orbital of the donor atom of the equatorial ligands to the 5 j and/or 6d-orbitals of uranium. The chemical shifts for the protons in the uranyl complexes are considered from the view of both the magnetic anisotropy of the uranyl group and the shielding of protons due to the drainage of electron density between ligand and metal. It is found that the difference of the chemical shifts between H, and H b protons is caused mainly by the deshielding due to the anisotropic field of the uranyl group. REFERENCES I. G. F. Svatos, C. Curran and J. V. Quagliano, J. Am. chem. Soc. 77, 6159 (1955). 2. A. G. Hill and C. Curran, J.phys. Chem., Ithaca64, 1519 (1960). 3. M. G. Cingi, C. Guastini, A. Musatti and M. Nardelli, Acta. crystallogr. B25, 1833 (1969). 4. Y. H. Deshpande and V. R. Rao, Indian J. Chem. 7, 1051 (1969). 5. L. M. Manojlovic, Bull. Inst. nucl. Sci. Boris Kidrich 8, 105 (1958). 6. V. Amirthalingam and V. P a d m a n a b h o m , Analyt. Chem. 31,622 (1959). 7. W. H. Zachariasen, Acta crvstallogr. 7, 795 (1954). 8. S. P. McGlynn, J. K. Smith and W. C. Neely, J. chem. Phys. 35, 105 (1961). 9. W. H. Zachariasen, Acta ct3'stallogr. 8, 847 (1954). 10. L. H. Jones, Spectrochim. Acta 10, 395 (1958). 11. G. K. Conn and C. K. Wu, Trans. Farada.v Sac. 34, 1483 (1938). 12..I.I. Bullock and F. W. Parret, Can. J. Chem. 48, 30t~5 (1970). 13. J. P. Day and k. M. Venanzi, J. chem. Soc. (A), 13fl3 (19661.

2021

14. F. A. Hart and J. E. Newbery, ,l. inorg, nucl. Chem. 30, 318 (1968). 15. 1. J. Ahuja and R. Singh, J. inorg, nucl, Chem. 35, 561 (1973). 16. S. P. McGlynn and J. K. Smith, J. molec. ,S)wctros~. 6. 164(1961). 17. C. G. Walrand and L. G. Vanquickenborne, J. ~ht'm. Phys. 54, 4178 (1971). 18. A. Pasini, M. Gullotti and E. Cesarotti, J. inorg, m,'l. Chem. 34, 3821 (1972). 19. T. tt. Siddall and C. A. Prohaska. lnorg. ('hem. 4. 783 (1965). 20. M. S. Subramanian, S. A. Pai and V. K. Manchanda, Aust. J. Chem. 26, 85 (1973). 21. M. S. Subramanian and V. K. Manchanda, ./. morg. lutc]. ('hem. 33, 3001 (1971). 22. L. Fernandes, Atli. Accad. naz. Lintel 1,439 (1925). 23. 1. 1. Chernyaev, Complex Compounds o/Uranium. Israel Program for Scientific Translations, Jerusalem (1966). 24. T. Nakai, Muki Kagaku Zensyo XII-I Uranium, p. 69 Maruzen, Tokyo (1953). 25. K. Nakanishi, Sekigaisen Kyusyu Spectra, p. 130. N ankodo, Tokyo (1960). 26. D. Hall, A. D. Rae and T. N. Waters, Acta cry~'tallogr, 22, 258 (1967). 27. A. Corsini. J. A b r a h a m and M. T h o m p s o n , Chem Comm, l l01 (1967). 28. J. I. Bullock. J. inorg, nucl. Chem. 29, 2257 (1967). 29. ( . C, Addision and W. B. Simpson. J. chem. So~. 598 (1965), 30. K. Nakamoto, Y. Morimoto and A. F. Martell, J. ,4m. chem. So~. 83, 4533 (1961). 31. J. C Ei~enstein and M. H. L. Pryce, Pro('. Rat. So¢. Lond. A229, 20 (1955). 32. C A. Coulson and G. R. Lesler, J. ¢ltent ,S'o~ 3650 (1956). 33. J. A. Pople, W. G. Schneider and H. I. Bemstein, Hi~,,h Re~olution Nuclear Magnetfl' Resonance. McGrawHill, New York (1900). 34. ( . J. Brown, Pro¢, Rot'. Soc. Land. A302. 185 {1968).