Synthesis and characterization of lanthanide(III) nitrate complexes with Terdentate ONO donor hydrazone derived from 2-benzimidazolyl mercaptoaceto hydrazide and o-hydroxy aromatic aldehyde

Article abstract of DOI:10.1155/2011/743948

A few eight coordinated complexes of lanthanide(III) nitrate with 2-benzimidazolyl mercaptoaceto hydrazone ligand (LH₂) with the general formula [Ln(LH)₂NO₃]H₂O (where Ln = La, Pr, Nd, Sm and Gd) have been synth

Full text of DOI:10.1155/2011/743948

ISSN: 0973-4945; CODEN ECJHAO
E-Journal of Chemistry
2011, 8(4), 1900-1910
http://www.e-journals.net
Synthesis and Characterization of
Lanthanide(III) Nitrate Complexes with Terdentate
ONO Donor Hydrazone Derived from
2-Benzimidazolyl Mercaptoaceto Hydrazide and
o-Hydroxy Aromatic Aldehyde
VINAYAK M. NAIK and NIRMALKUMAR B. MALLUR§∗
Department of Chemistry, Government Arts and Science College
Karwar-581 301, Karnataka, India
§P G Department of Studies in Chemistry
Karnatak University, Dharwad-580 003, India
nirmalmallur@rediffmail.com
Received 6 October 2010; Accepted 16 December 2010
Abstract: A few eight coordinated complexes of lanthanide(III) nitrate with
2-benzimidazolyl mercaptoaceto hydrazone ligand (LH2) with the general
formula [Ln(LH)2NO3]H2O (where Ln = La, Pr, Nd, Sm and Gd) have been
synthesized and characterized by elemental analysis, magnetic susceptibility,
molar conductance, UV-Visible, IR and 1H NMR spectral studies. The
experimental data sustain stoichiometry of 1:2 (metal/ligand) for the
complexes. The spectral data shows that the ligand reacts in keto form and
behaves as monobasic terdentate in nature. The nitrate appears to coordinate in
the bidentate fashion to the metal ion. The thermal stabilities of the complexes
have been studied by TGA and their kinetic parameters were calculated using
Coats-Redfern and MKN methods. The antimicrobial activity studies have been
under taken and results are discussed.
Keywords: Hydrazone, Lanthanide(III) nitrate complexes, Spectral data, Kinetic parameters, Antimicrobial
activity
Introduction
The structural chemistry of the lanthanides is fascinating because they have a tendency to
form complexes with coordination number greater than six up to twelve. Due to the large
size of the ions and their tendency to form ionic bonds rather than covalent bonds lead to
complexes with higher coordination numbers. Not only monodentate or simple bidentate but

1901
N. B. MALLUR et al.
also polydentate ligands with small bytes often yield complexes with higher
coordination numbers1. The structural versatility arises from the lack of strong crystal
efforts for the 4f electronic configurations as well as from the large ionic radii of these
metal ions, which change markedly with oxidation number or atomic number of the
lanthanides. In recent years, the chemistry of hydrazones has been intensively
investigated, owing to their coordinative capability, their pharmacological activity2 and
their use in analytical chemistry as metal extracting agents. The study of the complexes
formed with hydrazones is very interesting because of the tautomerism exhibited by
these ligands. The chromophore group -CO-NH-N< of the ligand can enters the inner
sphere of the complex either in the keto or enol form. This tendency depends upon the
pH of the medium employed in the synthesis of the complex, the nature of the
substituents attached to the carbonyl carbon atom,
β - nitrogen atom, the anion of the
metal salt and the metal ion. The tautomeric nature of the hydrazone and its versatility
in showing higher coordination number of lanthanide ions attracted our attention to
carry out the studies on lanthanide complexes. In the continuation of earlier studies on
the complexes with the ligands of 2-benzimidazolyl mercaptoaceto hydrazide and
o-hydroxy aromatic aldehydes3-5, we report here the synthesis and structural studies of
few lanthanide(III) nitrate complexes with 2-benzimidazolyl mercaptoaceto hydrazones.
Experimental
All reagents and solvents were used are of the type AR grade and were used without
further purification. 2-benzimidazolyl mercaptoaceto hydrazide was prepared according
to reported standard method3,6. Lanthanum nitrate pentahydrate La(NO3)3.5H2O (99%)
was obtained from BDH chemicals Ltd. Other lanthanides were procured from Indian
Rare Earths Ltd., as oxides (99.9% pure). The corresponding metal nitrates were
prepared by dissolving a slight excess of respective lanthanide oxide in hot 50% (v/v)
nitric acid (25 mL). The undissolved oxide was removed by filtration in each case and
the filtrate was concentrated on a water bath to ∼25% of the original volume. The
resulting concentrate was cooled to obtain the crystals of lanthanide nitrate. The
lanthanide nitrates so prepared were used for the preparation of complexes. The metal
content in complexes was determined by complexometric EDTA titration using xylenol-
orange as indicator at pH 6. The nitrate present in the complexes is determined using a
nitron reagent. The elemental analyses of complexes were recorded on Elemental
analyzer Heraeus Carlo Erba-1108. The electronic spectra of lanthanide(III) nitrate
complexes were recorded in DMF on Hitachi 150-20 spectrophotometer in the region
200-900 nm, infrared spectra were recorded in KBr matrix using Impact-410 Nicolet
1
FTIR spectrometer in the range 4000-400 cm-1 and H NMR spectra were recorded in
DMSO solvent on Bruker Avance-300 spectrometer using TMS as an internal standard.
Molar conductances of the complexes were measured on Elico CM-82 conductivity
bridge in DMF solution at concentration ∼10-3 M. The magnetic susceptibilities were
measured at room temperature on Guoy balance using Hg[Co(SCN)4] as calibrant. TG
0
and DTG were carried out from room temperature to ∼800 C in dynamic air atmosphere
on a Rigaku TAS-100 model thermal analyzer maintaining a heating rate of 10 C/min.
0
Kinetic parameters were computed from the thermal decomposition data. The metal
complexes together with the hydrazone ligands were tested to emphasize their activities
against the two bacteria Escherichia coli and Bacillus cirroflagellasus and two fungal
species Aspergillus niger and Candida albicans.

Synthesis and Characterization of Lanthanide(III) Nitrate
1902
Preparation of 2-benzimidazolyl mercaptoaceto hydrazone ligand (LH2)
A mixture of an ethanolic solution of 0.001 mol of 2-benzimidazolyl mercaptoaceto
hydrazide and 0.001 mol of o-hydroxy aromatic aldehyde in ethanol was refluxed on a steam
bath for ∼3 h. The mixture was concentrated, cooled and the separated precipitate was
filtered, washed with water and recrystallised from alcohol. The purity of the ligand (LH2)
(Figure.1) was checked by TLC.
Figure 1. Structure of the ligand (LH2)
Preparation of lanthanide(III) nitrate complexes
An alcoholic solution of lanthanide(III) nitrate (0.01 mol/20 mL) was added to 2-benzimidazolyl
mercaptoaceto hydrazone (0.02 mol/20 mL ethanol) with constant stirring. The mixture was
refluxed on a water bath for ∼4 h and then pH of the mixture was raised to 6.5 by adding
dropwise alcoholic ammonia. The coloured complex thus formed was filtered, washed with
alcohol and then dried in vacuum over anhydrous CaCl2 in a desiccator (yield 68-76%).
Results and Discussion
The prepared lanthanide(III) nitrate complexes are coloured, non-hygroscopic and insoluble
in organic non-polar solvents like benzene, carbon tetrachloride etc., but soluble in organic
polar solvents like DMF and DMSO. From elemental analyses data (Table 1) reveal that the
lanthanide(III) nitrate complexes have a metal/ligand ratio of 1:2. The observed molar
conductance (Table 1) values measured in DMF solution fall in the range (18-27 omh-1 cm2
mol-1), these observed values of the molar conductance are well within the expected range
for non-electrolytes7. Therefore, the molar conductivity data suggest that the nitrate ion
present within coordination sphere in the complexes.
Magnetic susceptibility
Lanthanum(III) nitrate complexes are diamagnetic as may be expected from their closed
shell electronic configuration and absence of unpaired electron. The magnetic moments
obtained at room temperature for other tripositive lanthanide(III) nitrate complexes show
that paramagnetic nature. The magnetic moments observed are compared with the
theoretical spin orbital coupling values (the Hund’s values) and the values calculated form
Van Vleek formula of the respective lanthanide ion. These values agree with each other for
the lanthanide(III) nitrate complexes except samarium(III) nitrate complexes. This indicate
the non-involvement of 4f-orbitals in bond formation. In samarium(III) nitrate complex a
little deviation from Van Vleek values indicates little participation of 4f-electrons in bond
formation. In the samarium(III) nitrate complexes, a slight higher values observed may
presumably be due to temperature dependent magnetism8 on account of low J-separation.

1903
N. B. MALLUR et al.
Table 1. Analytical, molar conductance and magnetic susceptibility data of lanthanide(III)
nitrate complexes
Found (Calculated) %
Molar
conductance,
ohm-1 cm2 mol-1
µeff
(B.M.)
Ligand/Complex
C
H
N
Metal Nitrate
57.78
4.32
17.14
C16H14N4O2S (L1H2)
[La(L1H)2NO3]H2O
[Pr(L1H )2NO3]H2O
[Nd(L1H)2NO3]H2O
[Sm(L1H)2NO3]H2O
[Gd(L1H)2NO3]H2O
C17H16N4O2S (L2H2)
[La(L2H)2NO3]H2O
[Pr(L2H)2NO3]H2O
[Nd(L2H)2NO3]H2O
-
-
-
-
(58.89) (4.29) (17.18)
44.72 3.03 14.61 16.17
7.18
24.33
20.27
24.74
22.14
16.71
-
diam
3.42
3.45
1.21
7.76
-
(44.29) (3.02) (14.52) (16.01) (7.14)
44.08 2.98 14.47 16.23 7.10
(44.19) (3.01) (14.49) (16.20) (7.13)
44.27 3.03 14.57 16.61 7.03
(44.02) (3.01) (14.43) (16.52) (7.10)
43.86 2.92 14.45 17.14 7.02
(43.71) (2.98) (14.33) (17.10) (7.05)
43.17 2.91 14.37 17.64 7.06
(43.38) (2.95) (14.22) (17.74) (6.98)
59.12
(60.01) (4.70) (16.47)
45.26 3.34 14.02 15.69
4.63
16.26
-
-
6.88
17.94
21.96
19.08
18.16
21.44
-
diam
3.46
3.48
1.23
7.69
-
(45.59) (3.37) (14.07) (15.50) (6.92)
45.61 3.33 14.07 15.78 6.87
(45.48) (3.36) (14.04) (15.69) (6.91)
44.96 3.52 13.89 15.95 6.83
(45.22) (3.54) (13.96) (15.98) (6.87)
44.67 3.46 13.81 16.38 6.72
[Sm(L2H)2NO3]H2O (44.91) (3.52) (13.87) (16.55) (6.81)
45.01 3.37 13.62 16.98 6.67
(44.67) (3.30) (13.79) (17.20) (6.78)
[Gd(L2H)2NO3]H2O
C17H16N4O3S (L3H2)
[La(L3H)2NO3]H2O
[Pr(L3H)2NO3]H2O
[Nd(L3H)2NO3]H2O
[Sm(L3H)2NO3]H2O
[Gd(L3H)2NO3]H2O
Electronic spectra
56.01
(57.30) (4.49) (15.73)
43.55 3.42 13.48 14.79
4.51
15.76
-
-
6.52
22.16
18.44
21.11
18.32
20.92
diam
3.41
3.42
1.20
7.73
(43.92) (3.44) (13.56) (14.95) (6.67)
44.03 3.22 13.44 15.25 6.68
(43.82) (3.24) (13.52) (15.12) (6.65)
43.41 3.27 13.52 15.57 6.68
(43.67) (3.27) (13.48) (15.42) (6.63)
43.49 3.24 13.36 16.23 6.64
(43.38) (3.21) (13.39) (15.97) (6.58)
42.94 3.33 13.24 16.47 6.52
(43.07) (3.37) (13.31) (16.60) (6.54)
The electronic spectra of ligands show bands at 30550-26985, 33248-30010 and
34630-32980 cm-1 whereas in lanthanide(III) nitrate complexes these bands are shifted to
higher or lower frequency sides. This shift may be due to ligand to metal charge transfer
transitions9,10. No absorption band due to f-f transition of lanthanide(III) ions could be
located in the visible region in the spectra of the complexes. This is probably due to the fact
that the f-f bands are weak and are obscured by the intense charge transfer bands10,11
.

Synthesis and Characterization of Lanthanide(III) Nitrate
1904
Infrared spectra
The IR spectra analysis gave information about the mode of coordination of the ligand (LH2)
to the lanthanide(III) ions. The characteristic bands are presented in Table 2. The IR spectra
of ligands show strong sharp bands in the regions 3230-3214, 3018-3010 and 1524-1502 cm-1
are assigned to the vibrations of υ(N-H) of hydrazide, υ(N-H) of imidazole moiety and
phenolic υ(C-O) respectively5. The broad band around 3445-3420 cm-1 in the IR spectra of
ligands assigned to υ(OH), which were found to have disappeared in all their respective
complexes, thereby indicating the involvement of phenolic oxygen in bondy with metal ions
through deprotonation and the positive shifting of phenolic υ(C-O) in all the complexes
confirms the involvement of phenolic OH in the complex formation. In the ligands a strong
sharp band observed in the region in the region 1705-1685 cm-1 is assigned to υ(C=O),
which was shifted to 23-41 cm-1 in all complexes indicates the involvement of the carbonyl
group in complexation with the metal ion and another strong sharp band observed in region
1652-1648 cm-1 is assigned to azomethine υ(C=N) group, lowering of υ(C=N) 26-32 cm-1 in the
complexes as compared to its ligand is due to the reduction of double bond character carbon-
nitrogen bond of the azomethine group11,12. The band due to υ(NH) remains unaltered in its
position and intensity, it clearly suggests the reaction of ligand in kero from. The broad
absorption band in the region 3490-3340 cm-1 indicates the presence of water molecule in the
complexes and further confirmed by thermogravimetric studies. The present lanthanide(III)
nitrate complexes show six absorption bands in the regions 1501-1469, 1302-1268, 1037-1017,
870-855, 765-750 and 703-687 cm-1 assigned to respectively to υ4, υ1, υ2, υ6, υ3 and υ5 vibrations
of the coordinated C2v nitrate group. The magnitude of υ4-υ1 and υ3-υ5 are in the range of 205-
195 cm-1 and 66-60cm-1 respectively indicates the nitrate group is in bidentate fashion13.
Table 2. Significant IR frequencies (cm-1) of the ligands and their lanthanide(III) nitrate
complexes
-
NO3 frequencies
Ligand/Complex
υ 4
υ1
υ2 υ6 υ3 υ5
C16H14N4O2S (L1H2)
[La(L1H)2NO3]H2O
[Pr(L1H )2NO3]H2O
[Nd(L1H)2NO3]H2O
[Sm(L1H)2NO3]H2O
[Gd(L1H)2NO3]H2O
C17H16N4O2S (L2H2)
[La(L2H)2NO3]H2O
[Pr(L2H)2NO3]H2O
[Nd(L2H)2NO3]H2O
[Sm(L2H)2NO3]H2O
[Gd(L2H)2NO3]H2O
C17H16N4O3S (L3H2)
[La(L3H)2NO3]H2O
[Pr(L3H)2NO3]H2O
[Nd(L3H)2NO3]H2O
[Sm(L3H)2NO3]H2O
[Gd(L3H)2NO3]H2O
3230 3010 1705 1650 1524
-
-
-
-
-
-
-
-
3228 3008 1676 1622 1546 492 428 1497 1294 1026 863 759 698
3230 3010 1664 1620 1542 497 434 1474 1276 1025 849 756 695
3228 3014 1680 1618 1552 499 437 1498 1295 1028 863 758 695
3231 3012 1678 1622 1547 504 439 1491 1292 1036 869 765 701
3232 3010 1674 1618 1541 497 431 1497 1299 1029 861 763 698
3222 3018 1685 1648 1502
-
-
-
-
-
-
-
-
3210 3020 1662 1616 1540 488 419 1486 1287 1017 856 750 687
3219 3016 1658 1618 1546 484 426 1480 1282 1023 860 754 690
3218 3020 1662 1622 1549 486 426 1501 1301 1034 858 756 690
3220 3018 1653 11621 1539 499 436 1498 1302 1033 860 759 699
3218 3016 1662 1622 1536 499 439 1488 1296 1037 859 765 702
3214 3014 1696 1652 1513
-
-
-
-
-
-
-
-
3216 3012 1670 1626 1538 502 431 1469 1268 1030 861 753 692
3215 3013 1672 1624 1539 492 434 1493 1297 1031 869 763 703
3214 3010 1666 1612 1542 501 440 1488 1290 1030 855 761 698
3215 3016 1668 1622 1540 488 427 1487 1288 1027 863 759 697
3216 3012 1672 1620 1529 482 422 1488 1292 1033 865 758 696

1905
N. B. MALLUR et al.
Apart from these, two other non-ligand bands are also observed, one weak band
observed in the range of 504-482 cm-1 which may be attributed to υ(M-O) and the other
weak around 440-419 cm-1 which may be assigned to υ(M-N) vibrations. The band υ(M-O)
usually occurs at higher frequency than υ(M-N) and υ(M-O) band usually broad and
stronger than the υ(M-N) band. This may be due to large dipole moment change in the
vibration of M-O band in comparison to that in the M-N band11,12
.
1H NMR spectra
The spectrum of 1H NMR in DMSO-d6 solvent used. In the ligand, the eight aromatic protons
have resonated in region δ7.26-7.93 ppm (m, 8H, Ar-H) as multiplet, in La(III) nitrate complex
these protons have been observed in the region δ7.18-7.79 ppm (m, 8H, Ar-H) as multiplet.
The peaks appear at δ12.08 ppm (s, 1H, phenolic-OH), δ11.05 ppm (s, 1H, -NH of hydrazine),
δ12.72 ppm (s, 1H, -NH of imidazole moiety), δ3.64 ppm (s, 2H, -CH2) and δ8.82 ppm (s, 1H,
-CH=N) as singlets in the ligand, but in the case of La(III) nitrate complex the peak of phenolic
–OH has been disappeared indicating the involvement of phenolic oxygen in the coordination
via deprotonation. The peaks of both the –NH group are unaffected in the spectrum of the
complex. The –CH2 peak is appeared at δ4.25 ppm in the complex, this downfield shift
suggest its deshielding because of the coordination of carbonyl group and the peak of the
azomethine proton is situated through a lower field with δ=0.22 ppm, this deshielding results
the coordination through the nitrogen of the azomethine group to the metal ion. The 1H NMR
data gave information that the ligand is in keto form and it coordinated to the metal atom
through the carbonyl oxygen, azomethine nitrogen and phenolic oxygen via deprotonation.
Thermal analysis
The thermal behaviour including the stability ranges, peak temperatures, percentage of weight
loss and percentage of residue obtained after decomposition process of the representative
complexes have been reported in Table 3. The thermoanalytical studies of the complexes reveal
that, the decomposition proceeds into three stages. The complexes undergo the first stage of
decomposition in the range 328-408 K, the weight loss corresponds to the loss of one
uncoordinated water molecule in the lattice while the second stage decomposition occurs in the
range 378-718 K, the weight loss indicates the loss of one nitrate and one ligand molecule. The
third stage decomposition occurs in the range 678-998 K, indicating the loss of another ligand
molecule. A plateau is obtained, which indicates the formation of stable metal oxides (Ln2O3).
The weight of the residue obtained agrees well with the calculated value. The kinetic parameters
(Table 4) were calculated using the coats-redfern and MKN equations14 by graphical as well as
least square method (Figure 2 and 3). On the basis of energy of activation values, we found that
the complexes show similar type of the decomposition reactions15. The energy of activation (Ea)
for the decomposition of lattice water was found to be much lower than that for coordinated
water and values are closer to the activation energy values for the dehydration reactions16. The
energy of activation values for the second stage of decomposition of the complexes was found to
be lower than those for the third stage decomposition, which indicates an increased rate at this
state and might be due to the catalytic effect of the metal complex in the oxidation for the ligands
and other decomposition products17. The rate of third stage decomposition of the complexes was
found to be much higher than the previous two stages due to the higher in energy of activation.
The negative entropy of activation values for all degradation stages show that the complexes are
more ordered in the activated state through the chemisorption of oxygen and other decomposition
products15. The negative entropy of activation values are compensated by the values of the
energies of activation. The entropy of activation value increases from first step to third step
indicates that the rate of decomposition decreases in stepwise reactions18.

Table 3. Thermogravimetric characteristics of lanthanide(III) nitrate complexes
Decomposition Peak
temp. range,
K
Weight loss,
%
Residue
nature
Decomposition
product
No. of Residue
moles
Obs(Cald)
Complex
Process
temp.
K
Obs. Calcd.
2.05 2.07
[La(L1H)2NO3]H2O
Dehydration
Decomposition of
coordination sphere
(L1H and NO3)
348-408
378
H2O
1
1
1
L1H and
NO3
42.57
43.01
408-678
508
Decomposition of
coordination sphere (L1H)
Dehydration
37.82
(37.56)
678-958
358-398
853
371
L1H
35.94 35.42
2.03 2.03
1
La2O3
Nd2O3
Gd2O3
[Nd(L1H)2NO3]H2O
H2O
L1H and
NO3
1
Decomposition of
coordination sphere
(L1H and NO3)
1
1
398-718
503
42.60 42.60
34.78 34.78
Decomposition of
coordination sphere (L1H)
38.84
(38.57)
718-978
805
L1H
1
[Gd(L3H)2NO3]H2O
Dehydration
Decomposition of
coordination sphere
(L3H and NO3)
328-378
378-708
358
521
H2O
L3H and
NO3
1.87 1.87
41.96 41.96
1
1
1
Decomposition of
coordination sphere (L3H)
38.50
(38.22)
708-998
818
L3H
35.47 35.47
1

1907
N. B. MALLUR et al.
Table 4. Kinetic parameters of complexes using Coats-Redfern (MKN) equation
Decomposition
Complex
stage
[La(L1H)2NO3]H2O(C1)
[Nd(L1H)2NO3]H2O(C7)
[Gd(L5H)2NO3]H2O(C15)
I
II
III
I
13.6075
(13.5737)
39.5023
7.1876
(4.2784)
-231
(-235) (0.9986)
-167 0.9970
(-172) (0.9972)
-104 0.9976
(-107) (0.9980)
-222 0.9997
(-218) (0.9997)
-195 0.9984
(-200) (0.9988)
-101 0.9990
(-104) (0.9981)
-215 0.9992
(-129) (0.9994)
-188 0.9986
(-219) (0.9976)
-112 0.9980
(-113) (0.9988)
0.9982
21.388×103
(10.974×103)
31.012×104
(24.226×104)
33.2416
(39.1788)
48.7880
(48.2668)
15.5843
(15.2123)
26.8450
(21.0524)
6.93×102
(4.0395×102)
55.287×104
(52.078×104)
47.5916
II
III
I
(26.7779)
52.6692
(52.5357)
17.2690
(17.4269)
28.5178
(29.7628)
1.721×103
(1.006×103)
5.042×104
(3.4613×104)
II
III
(28.4706)
42.6876
(42.4025)
1/Tx103
1/Tx103

Synthesis and Characterization of Lanthanide(III) Nitrate
1908
1/Tx103
Figure 2. Coats-Redfern plots for the three decomposition steps of the complexes
◊[La(L1H)2NO3]H2O; ∆[Nd(L1H)2NO3]H2O and *[Gd(L5H)2NO3]H2O]
1/Tx103
1/Tx103
1/Tx103
Figure 3. MKN plots for the three decomposition steps of the complexes
◊[La(L1H)2NO3]H2O; ∆[Nd(L1H)2NO3]H2O and *[Gd(L5H)2NO3]H2O]
Antimicrobial activity
The antimicrobial activity was carried out using cup plate method19 with two different
bacteria Escherichia coli and Bacillus cirroflagellasus and two fungal species Aspergillus
niger and Candida albicans on base layer medium. The antimicrobial activity results of the
screened compounds are given in the Table 5. The activity of the hydrazones have not
profoundly increased on complexation with lanthanide(III) ions. Sm(III) and Gd(III)
complexes are moderately active against Bacillus cirroflagellosus, Pr(III) and Nd(III) complexes

1909
N. B. MALLUR et al.
are moderately active against Excherichia coli. Overall the ligands and their lanthanide(III)
complexes are less active as compared to the standards Cotrimoxazole and Flucanozole used
in the present study.
Table 5. Antimicrobial activity of ligands and their lanthanides(III) nitrate complexes
Antibacterial activity of zone
of inhibition, mm
Antifungal activity of zone
of inhibition, mm
Compound
B. cirrof
E. Coli
A. niger
C. albicans
lagellasus
C16H14N4O2S (L1H2)
C17H16N4O2S (L2H2)
C17H16N4O3S (L3H2)
[La(L1H)2NO3]H2O
[La(L2H)2NO3]H2O
[La(L3H)2NO3]H2O
[Pr(L1H )2NO3]H2O
[Pr(L2H)2NO3]H2O
[Pr(L3H)2NO3]H2O
[Nd(L1H)2NO3]H2O
[Nd(L2H)2NO3]H2O
[Nd(L3H)2NO3]H2O
[Sm(L1H)2NO3]H2O
[Sm(L2H)2NO3]H2O
[Sm(L3H)2NO3]H2O
[Gd(L1H)2NO3]H2O
[Gd(L2H)2NO3]H2O
[Gd(L3H)2NO3]H2O
Contrimoxazole
14
13
14
15
13
15
14
14
15
15
14
14
18
17
18
17
17
18
24
-
13
14
12
14
15
13
16
17
16
17
18
16
15
15
13
14
15
13
21
-
15
14
13
16
14
14
15
15
14
16
14
13
16
14
14
15
15
14
-
14
13
12
15
14
14
14
14
15
15
14
13
14
14
13
15
13
14
-
Flucanozole
24
23
Conclusion
Based on the elemental analysis and various physicochemical studies the empirical formula
[Ln(LH)2NO3]H2O (Figure 4) have been tentatively proposed for the present complexes involving
a monobasic terdentate functional ligand in keto form and an eight coordinate metal ion.
Figure 4. Structure of lanthanide(III) nitrate complex

Synthesis and Characterization of Lanthanide(III) Nitrate
1910
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