Ligational behavior of furfurylidene(N-benzoyl)glycyl hydrazone toward some transition metal ions

Full text of DOI:10.1081/SIM-100001943

Synthesis and Reactivity in Inorganic and Metal-Organic
Chemistry
ISSN: 0094-5714 (Print) 1532-2440 (Online) Journal homepage: http://www.tandfonline.com/loi/lsrt19
LIGATIONAL BEHAVIOR OF FURFURYLIDENE(N-
BENZOYL)GLYCYL HYDRAZONE TOWARD SOME
TRANSITION METAL IONS
R. K. Lonibala , N. I. Devi , R. K. B. Devi & T. R. Rao
To cite this article: R. K. Lonibala , N. I. Devi , R. K. B. Devi & T. R. Rao (2001) LIGATIONAL
BEHAVIOR OF FURFURYLIDENE(N-BENZOYL)GLYCYL HYDRAZONE TOWARD SOME TRANSITION
METAL IONS, Synthesis and Reactivity in Inorganic and Metal-Organic Chemistry, 31:1, 179-194,
DOI: 10.1081/SIM-100001943
To link to this article: http://dx.doi.org/10.1081/SIM-100001943
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Date: 21 December 2016, At: 22:30

SYNTH. REACT. INORG. MET.-ORG. CHEM., 31(1), 179–194 (2001)
LIGATIONAL BEHAVIOR OF
FURFURYLIDENE(N-BENZOYL)GLYCYL
HYDRAZONE TOWARD SOME
TRANSITION METAL IONS
R. K. Lonibala,1,∗ N. I. Devi,1 R. K. B. Devi,1
and T. R. Rao2
1Chemistry Department, Manipur University,
Canchipur 795 003, India
2Department of Chemistry, Banaras Hindu
University, Varanasi 221 005, India
ABSTRACT
Furfurylidene(N-benzoyl)glycyl hydrazone, FBzGH, has
been synthesized and characterized. Transition metal complexes
of the formulae [M(FBzGH)2Cl(H2O)]Cl (M = Mn, Cu, Zn, Cd,
Hg), [Co(FBzGH)2]Cl2 · H2O and [Ni(FBzGH)2Cl2] · H2O were
isolated from acidic solutions and the complexes [M(FBzG)2
(H2O)2] (M = Co, Ni, Cu), from neutral solutions. Elemental analy-
ses, molar conductances, magnetic susceptibilities, electronic, pH-
metric, ESR, IR, and NMR studies have been carried out on these
complexes to illuminate the ligational behavior of FBzGH toward
the divalent metal ions. Formation constants of the metal chelates
were determined pH-metrically in aqueous dioxane. IR and NMR
∗Corresponding author. E-mail: rkloni@usa.net
179
Copyright ꢀ 2001 by Marcel Dekker, Inc.
www.dekker.com
C

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LONIBALA ET AL.
spectra suggest a bidentate nature of the hydrazone coordinating
as a neutral species in the adducts and as a uninegative one in
1
the neutral complexes. H NMR spectra indicate the presence of
two different conformers of the ligand at room temperature even
after complexation. However, these spectra show coalescence of
the peaks at a temperature higher than 340 K indicating that one
of the conformers gets stabilized at a higher temperature. A highly
shielded chemical shift value of (113). Cd NMR suggests a strongly
bound but weakly coordinated Cd2+ ion.
INTRODUCTION
The chemistry of hydrazones has been intensely investigated owing to their
coordinative capability (1), their pharmacological activity (2), and their use in an-
alytical chemistry as metal extracting agents (3). We, therefore, have undertaken a
systematic investigation of the coordination behavior of a number of hydrazones
derived from interactions of amino acid hydrazides with different aldehydes and
ketones, with 3d (4,5) and 4f (6,7) block elements. We report here the results of our
studies on the ligational behavior of a hydrazone derivative obtained from the con-
densation of N-benzoyl glycine hydrazide with furfuraldehyde, furfurylidene(N-
benzoyl)glycyl hydrazone (Fig. 1) and characterization of the complexes of the
hydrazone with some bivalent transition metal ions.
RESULTS AND DISCUSSION
Characterization of FBzGH
The solid state IR spectrum of FBzGH shows bands at 1675, 1545 cm−1and
1630, 1520 cm−1, which may be assigned to the amide I and II frequencies of the
hydrazide and benzamide carbonyl groups while the bands observed at 1570 and
1015 cm−1 are due to γ (C N) and γ (N−N) modes, respectively.
=
H
H
O
N
α′
3′
5′
2′
N
α
1
N
4′
H
O
O
2
4
3
Figure 1. Structure of FBzGH.

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181
1
In the H NMR spectrum, the hydrazide −NH− and the −NCH− groups
exhibit sharp singlets at δ 11.70 and 8.30 whereas the furane and phenyl ring
protons are observed as multiplets at δ 8.07–7.67 and 7.00–6.73, respectively. The
doubling of the signals due to the benzamide −NH− and the −CH2− protons at
δ 9.07, 8.67 and 4.53, 4.13 shows the existence of two predominant isomers at room
temperature (296 K). As the temperature is raised, coalescence of the isomeric
peaks is clearly observed over the range of temperature 296–348 K, as shown in
Figure 2. This observation is consistent with a single isomer predominating, or
two or more isomers being in the fast exchange limit of the NMR time scale. The
spectrum after deuterium exchange is devoid of the signals due to the benzamide
−NH and hydrazide −NH groups.
All the signals in the 13C NMR spectrum have been approximated applying
the substituent additivity (8). The numbering of the carbon atoms is as shown
in Figure 1. The 13C-NMR spectrum of the ligand corresponds to the presence
of more than one isomer of the ligand at 296 K and the predominance of only
Figure 2. 1H-NMR spectral peaks of (I) FBzGH and (II) [Cd(FBzGH)2Cl(H2O)]Cl as a
–
–
–
–
function of temperature. (a) Benzamidic NH and (b) CH2 signals.

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LONIBALA ET AL.
Figure 3. Mass spectrum of FBzGH.
one isomer at 348 K. The hydrazide >CO absorbs at 169.25 ppm whereas the
benzamide >CO shows two sharp peaks at 166.87 and 166.12 ppm.
In the mass spectrum (Fig. 3), the base peak observed at 105 m/e corre-
sponds to C6H5CO+. The molecular ion peak (M+) appears with 40% intensity at
m/e = 271. The possible fragments of FBzGH corresponding to the other peaks
with appreciable intensity are shown in Figure 4.
Characterization of the Complexes
Analytical data of the complexes (Table 1) indicates that FBzGH forms
two types of complexes as a function of pH i.e., addition/chloro and neutral/
deprotonated complexes having 1:2 (metal:ligand) ratio as represented by the
following equations:
EtOH
MCl2 · mH2O + 2FBzGH H
MCl2 · mH2O + 2FBzGH H
ꢀ
NaOH
ꢀ
H M(FBzGH)2Cl2H2O + (m − 1)H2O
H [M(FBzG)2(H2O)2] + (m − 2)H2O
+ 2HCl
All of the complexes are stable under ordinary conditions and decompose
at specific temperatures. They are insoluble in water and common organic sol-
vents except DMF and DMSO. Their molar conductances (9) in 0.001 M DMSO
solutions show the divalent Mn, Cu, Zn, Cd, Hg adducts to be 1:1 electrolytes,

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183
O
H
H
N
N
H
N
O
O
m/e 271
−
CO
O
C
HN N
C
N
H
O
O
m/e 162
m/e 109
−
CO
O
CH2
N
O
H
m/e 67
m/e 134
HCN + H2
C
O+
m/e 105
−
CO
m/e 77
Figure 4. Possible fragments of FBzGH.
the Co adduct to be a 1:2 electrolyte and the remaining complexes nonionic
species.
Magnetic Moments and Electronic Spectral Data
The µeff values and the band maxima observed in the electronic spectra of
the complexes are given in Table 2. The µeff values of Mn(II) and of both the Cu(II)
complexes are as expected for five and one unpaired electrons and do not infer any
information regarding their stereochemistries. However, the electronic spectra of
the Cu(II) complexes show bands at 14,286 and 15,385 cm−1 in the adduct and
neutral complexes, respectively, due to the transition 2Eg → 2T2g(D) indicating a

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LONIBALA ET AL.
Table 1. Colour, Analytical, and Molar Conductance Data of the Complexes of FBzGH
Molar
Complex
Empirical Formula;
(Formula Weight)
Conductance
Found (Calcd) %
Yield m.p.
(ꢀ−1 cm2
Colour (%) (◦C) Metal
Cl
N
N2H4
mol−1
)
FBzGH
Light
brown
Light
80 192
–
–
15.44 11.80
(15.50) (11.81)
–
C14H13N3O3; (271)
[Mn(FBzGH)2-
Cl(H2O)]Cl
70 112d 8.21 10.30 11.99 9.00
(8.01) (10.35) (12.25) (9.33)
20.93
–
MnC28H28
yellow
Light
N6O7Cl2; (686)
[Cu(FBzGH)2-
Cl(H2O)]Cl
65 200d 9.10 10.27 11.89
(9.15) (10.22) (12.09)
–
CuC28H28-
green
Light
N6O7Cl2; (695)
[Zn(FBzGH)2-
Cl(H2O)]Cl
65 157d 9.50 10.22 11.78 9.59
(9.39) (10.20) (12.06) (9.19)
26.03
21.50
28.11
99.16
ZnC28H28-
yellow
N6O7Cl2; (697)
[Cd(FBzGH)2-
Cl(H2O)]Cl
Cream 75 172d 14.97 9.88 10.97 8.43
(15.12) (9.55) (11.30) (8.61)
CdC28H28-
N6O7Cl2; (744)
[Hg(FBzGH)2-
Cl(H2O)]Cl
Cream 60 155d 24.27 8.20 10.12 7.68
(24.12) (8.54) (10.10) (7.70)
HgC28H28-
N6O7Cl2; (832)
[Co(FBzGH)2]-
Cl2.H2O
Green 68 182d 8.40 10.01 12.17 9.27
CoC28H28N6O7Cl2; (690)
[Ni(FBzGH)2Cl2]H2O
NiC28H28N6O7Cl2; (690) green
[Co(FBzG)2(H2O)2]
CoC28H28N6O8; (635)
[Ni(FBzG)2(H2O)2]
NiC28H28N6O8; (634)
[Cu(FBzG)2(H2O)2]
CuC28H28N6O8; (640)
(8.54) (10.29) (12.18) (9.28)
Light
68 219d 8.23 10.00 12.03 9.50
(8.51) (10.29) (12.18) (9.28)
12.45
Pink
70 206d 9.30
(9.28)
–
–
–
13.21 10.00
(13.23) (10.07)
12.90 10.05
(13.23) (10.07)
–
–
–
Light
70 200d 9.05
(9.25)
Green 70 267d 9.70
(9.94)
13.13
–
(13.13)
d: Decomposition temperature.
distorted-octahedral geometry (10) of the complexes. The [Ni(FBzGH)2Cl2] · H2O
and [Ni(FBzG)2(H2O)2] complexes show the magnetic moments 3.26 and
3.28 B.M., respectively, which correspond to an octahedral chromophore that is
further supported by the electronic bands observed at 9091 (γ 1), 14,085 (γ 2), and
23,810 (γ 3) cm−1 and 10,020 (γ 1), 14,670 (γ 2), and 22,320 (γ3) cm−1 due to
3
3
3
3
the transitions A2g(F) → T2g(F), T1g(F), and T1g(P), respectively, of an oc-
tahedral stereochemistry (11). A tetrahedral (12) geometry has been assigned to

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185
Table 2. µeff Values, Electronic Absorption Bands, and Assigned Transitions of
the Complexesa
Complexes
µeff (B.M.)
Bands (cm−1
18868
12346 sh, 14286
15385
9091, 14085
23810
10020, 14670
22320
)
Transitions
4
[Mn(FBzGH)2Cl(H2O)]Cl
[Cu(FBzGH)2Cl(H2O)]Cl
[Cu(FBzG)2(H2O)2]
5.27
2.00
2.08
3.26
6A1g → T1g(G)
2
2B1g → A1g, 2B2g
2
2B1g → B2g
3
[Ni(FBzGH)2Cl2]H2O
3A2g → T 2g, 3T1g(F)
3
→ T1g(P)
3
[Ni(FBzG)2(H2O)2]
[Co(FBzGH)2]Cl2 · H2O
[Co(FBzG)2(H2O)2]
3.28
4.05
4.67
3A2g → T2g, 3T1g(F)
3
→ T1g(P)
4
6452
4A2 → T1(F)
14493, 15038, 16000 4A2 → T1(P)
4
4
9901, 13793
19802
4T1g → A2g, 4T2g(F)
4
→ T1g(P)
sh = Shoulder.
aThe spectra were recorded as Nujol mulls.
[Co(FBzGH)2]Cl2 · H2O based on its µeff value (4.05 B.M.) and electronic absorp-
tion bands observed as a broad band at 6450 cm−1 that may be due to the transition,
4
4A2 → T1(F) and a multiplet at 14,493, 15,038, 16,000 cm−1 due to the transition
4
4A2 → T1(P) for a d7 tetrahedron. The magnetic moment of [Co(FBzG)2(H2O)2]
is 4.67 B.M. and the electronic bands observed at 9901, 13,793, and 19,802 cm−1
4
assignable to the transitions, 4T1g(F)→ A2g(F), 4T2g(F), and 4T1g(P), respectively,
suggest an octahedral geometry (10) around the metal ion.
Electron Spin Resonance Spectra
The ESR spectra of both Cu(II) complexes are isotropic at room temperature.
However, the spectra are anisotropic at LNT and are characteristic of axial symme-
try. The g and g values are 2.295 and 2.041 for the Cu(II) adduct and 2.276 and
⊥
2.061 for the Cu(II) deprotonated complex, respectively. The trend g > g > ge
⊥
indicates tetragonal elongation along the z-axis and the presence of the unpaired
electron in the b1g(dx2−y2) orbital (13). Large A values,140 and 163.3 G, and
in-plane σ-bonding parameters (α2) calculated for the Cu(II) complexes (0.71 and
0.76) depict a predominant covalent in-plane bonding (14) in these complexes.
Stability Constants of Co(II), Ni(II), and Cu(II) Complexes
The proton–ligand constants, log K1H, and the metal-ligand stability con-
stants, log K1, for the formation of the cobalt, nickel, and copper complexes with
FBzGH were obtained using Bjerrum’s half n-value method (15) modified by

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LONIBALA ET AL.
Table 3. Protonation Constants of FBzGH, Metal–Ligand Stability Constants, and Other
Thermodynamic Parameters for the Co(II), Ni(II), and Cu(II) Complexes of FBzGH at
Different Temperatures (T) and Ionic Strengths (µ)
H(I)
Co(II)
Ni(II)
Cu(II)
Protonation and metal-ligand stability constantsa
When µ is varied
0.00 M
–
11.4000 11.6000 12.4000
0.05 M
0.10 M
0.15 M
0.20 M
12.4000 13.5000 12.7050 13.2575
12.2075 13.2500 12.5555 13.2500
11.9500 12.2000 12.5025 13.1500
11.7050 11.9000 13.3025 13.0050
When T is varied
10◦C
12.4500 15.5000 12.9050 13.9050
11.7050 14.2550 12.9000 13.5550
11.9025 13.5000 12.7050 13.2575
12.5050 13.2500 12.3025 13.4000
12.7050 13.1000 11.9050 13.6550
20◦C
30◦C
40◦C
50◦C
Other thermodynamic parameters
−ꢁG◦
T = 10◦C
20.0726 16.7121 18.0071
19.1126 17.2959 18.1741
18.7181 17.6158 18.3819
18.9778 17.6207 19.1927
19.3624 17.5962 20.1827
T = 20◦C
T = 30◦C
T = 40◦C
T = 50◦C
−ꢁH◦ (kcals/mol) at T = 30◦C
2.5932
1.1443
1.3925
ꢁS◦ (cals/deg/mol) T = 30◦C
53.2170 54.3614 56.1000
ꢁG◦ = Change in free energy; ꢁH◦ = Change in enthalpy; ꢁS◦= Change in entropy.
aH(I) Values under these are Log K1H at 30◦C; Co(II), Ni(II), and Cu(II) values under
these are Log K1 at 30◦C.
Irving and Rossotti (16). The calculated (17) free energy (ꢁG◦), enthalpy (ꢁH◦),
and entropy (ꢁS◦) data are included in Table 3. The proton–ligand formation
curve (Fig. 5) shows that FBzGH loses only one proton whereas the metal-ligand
formation curve (Fig. 6) indicates the metal ligand stoichiometry to be 1:2 in these
complexes. ꢁG◦ values have been found to be negative suggesting spontaneity of
the formation of the complexes. ꢁG◦ values also indicate that low temperature
favors formation of the Co(II) complexes and high temperature favors formation
of the Ni(II) and Cu(II) complexes.
Infrared Spectra
The IR frequencies of the selected groups of the ligand and its complexes are
included in Table 4 along with the assignments. In order to avoid the complications

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187
Figure 5. Proton ligand formation curves of FBzGH at 10, 20, 30, 40, and 50◦C at 0.05 M
ionic strength.
due to intermolecular H-bonding, comparison of the spectra of the complexes
has been made with the solution spectrum of the ligand. The positions of the
amide I and II bands of the benzamide moiety remain unchanged in the spectra
of all the complexes indicating noncoordination of this group, and the retention
of these bands at 1630 and 1550 cm−1 shows the existence of H-bonding even
in the complexes. The amide bands of the hydrazidic carbonyl group undergo a
bathochromic shift, 40–65 cm−1 and 5–55 cm−1, in the spectra of the adducts
suggesting coordination through the above group (18) in these complexes. All of
these amide bands of the hydrazide group, however, are absent in the spectra of
–
=
=
the deprotonated complexes while a sharp band diagnostic of the >C N N C<
group appears at 1600 cm−1 indicating enolization of the hydrazidic carbonyl
group through amide ↔ imidol tautomerism and subsequent coordination of the
imidol oxygen (19) to the M2+ ion in the deprotonated complexes. The appearance
of two new peaks characteristic of γ (NCO−) at 1565 and 1305 cm−1 in the spectra
of the neutral complexes also supports the coordination of the imidol group (19).
Complexation through the azomethine nitrogen (20) has been inferred from the
observed bathochromic shift (25–35 cm−1) in γ (C N) and the hypsochromic
=
shift (5–20 cm−1) in the γ (N N) bands, in the spectra of the complexes. The
–
furane ring vibrations (21) at 1500, 885, and 750 cm−1 in the spectrum of the
metal-free FBzGH remain practically unaffected after complexation indicating
nonparticipation of the ring oxygen in bonding. The medium intensity bands in the
ranges 385–355, 340–320, and 305–250 cm−1 tentatively may be attributed to the

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LONIBALA ET AL.
Figure 6. Formation curves of Co(II), Ni(II), and Cu(II) complexes of FBzGH at 30◦C
(0.05 M).
–
–
–
γ (M O), γ (M N), and γ (M Cl) modes (22), respectively. The doubling feature
of the γ (Ni−Cl) band shows that the two chlorine atoms are cis to each other.
Nuclear Magnetic Resonance Spectra
The 1H and 13C NMR spectra of the ligand and the Zn(II), Cd(II), and Hg(II)
adduct complexes were recorded in DMSO-d6 solution and the spectral data are
1
included in Tables 5 and 6, respectively, along with their assignments. The H
– –
–
NMR spectra of the complexes show an upfield shift of the N NH CO signal
suggesting coordination of the carbonyl oxꢁygen and/or azomethine nitrogen (23).
The signal due to the N NH CO group (Cα) in the 13C NMR spectrum of FBzGH
– –
–

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189
Table 4. Infrared Spectral Data (cm−1) of the Complexes of FBzGH*a
Hydrazidic Moiety
Complex
Amide I
Amide II
γ (C=N)
γ (NN)
γ (MO)
FBzGH
1675 s
1720 s
1675 s
1670 s
1675 s
1675 s
1675 s
1655 s
1655 s
1545 s
1570 m
1545 s
1540 m
1545 s
1535 s
1545 s
1535 m
1555 m
1570 m
1600 m
1570 m
1560 m
1570 m
1570 m
1565 m
1570 m
1575 m
1015 s
1005 s
–
–
FBzGHa−
[Mn(FBzGH)2Cl(H2O)]Cl
[Cu(FBzGH)2Cl(H2O)]Cl
[Zn(FBzGH)2Cl(H2O)]Cl
[Cd(FBzGH)2Cl(H2O)]Cl
[Hg(FBzGH)2Cl(H2O)]Cl
[Co(FBzGH)2]Cl2·H2O
[Ni(FBzGH)2Cl2]H2O
1015 m
1010 w
1015 m
1015 m
1015 m
1015 m
1025 m
360 m
355c m
360 m
360 m
360 m
380 m
380 m
γ (NCO−)
Amide I
Amide II
γ (C=N)
γ (NN)
γ (MO)
[Co(FBzG)2(H2O)2]
[Ni(FBzG)2(H2O)2]
[Cu(FBzG)2(H2O)2]
1550 s
1550 s
1550 s
1305 s
1305 s
1300 s
1565 s
1565 s
1565 s
1015 s
1015 s
1015 s
385 m
385 m
370c m
s: Strong; m: Medium; w: Weak.
aThe spectra were recorded as Nujol mulls.
bIn acetonitrile solution.
cDoublet.
undergoes a downfield shift in the spectra of the complexes, suggesting coordina-
tion of the carbonyl group (24) while that due to the benzamide carbonyl group
(Cα) does not undergo any remarkable shift in the spectra of the complexes thereby
indicating its nonparticipation in bonding. The downfield shift observed in the
signals due to the −NCH− carbon also suggests coordination of the azomethine
nitrogen (25). The signals due to furane and phenyl rings remain almost unaltered
in both the 1H and 13C NMR spectra of the complexes suggesting their noninvolve-
ment in bonding. The 113Cd NMR spectrum of the Cd(II) complex was recorded
in DMSO-d6 solution and the chemical shift was referenced to external 1.0 M
CdSO4 in H2O. The resonance signal of the complex was observed as a single
line at −347.9 ppm, which is unusually shielded. This shielded nature of this reso-
nance reflects a strongly bound (nonexchanging) Cd2+, but one which is “weakly
coordinated electronically” (26). “Weakly coordinated electronically” means that
the bonding in this complex is more ionic rather than the usual donor–acceptor
relation between a ligand and a metal such as cadmium. The highly shielded na-
ture of the complex implies substantially less covalency of the metal–ligand bond
resulting in a smaller perturbation from the isolated ion electronic configuration.
Nonetheless, the metal ion is far from free. Though weakly covalently ligated, the
Cd2+ is strongly bound.

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Table 5. 1H NMR Spectral Data (δ) of FBzGH and the Zn(II), Cd(II), and Hg(II)
Complexesa
Complexes[M(FBzGH)2(H2O)Cl]Cl
FBzGH
Cd(II)
(296 K)
Zn(II)
(296 K)
Hg(II)
(296 K)
Proton(s)
– –
(296 K)
(384 K)
(353 K)
–
–
N NHCO
11.70
9.07, 8.67
8.30
4.53, 4.13
8.07 m
7.67 m
7.00
11.43
8.60
8.17
11.41
8.99, 8.60
8.10
4.33, 3.98
7.88 m
7.48 m
6.83
11.43
9.00, 8.80
8.27
4.47, 4.10
8.00 m
7.60 m
6.97
11.24
8.47
8.13
4.27
7.95
7.83
6.90
6.65
11.58
8.99, 8.81
8.27
4.49, 4.41
8.04
C6H5CONH
–
–
–
–
NCH
CH2
4.40
Phenyl
Protons
Furane
Protons
8.10 m
7.63 m
6.93
7.68
7.02
6.77
6.73 m
6.73 m
6.55 m
6.71
m: Multiplet.
aThe spectra were recorded in DMSO-d6.
Thus, the ligand FBzGH was found to behave as a neutral bidentate ligand
coordinating through the hydrazidic carbonyl oxygen and the azomethine nitrogen
in the adducts while it behaves as an uninegative bidentate ligand bonding through
the enolic oxygen of the hydrazidic carbonyl group and azomethine nitrogen. The
proposed structures of the complexes are given in Figure 7.
Table 6. Proton-Noise Decoupled 13C NMR Spectral Data (ppm) of FBzGH and the
Zn(II), Cd(II), and Hg(II) Complexesa
FBzGH
296 K
Complex, M(FBzGH)2(H2O)Cl]Cl at 296 K
Carbon
Atoms
348 K
Zn(II)
Cd(II)
Hg(II)
Cαꢁ
Cα
169.25
166.87,166.12
40.77
–
170.22
166.75, 166.30
41.28
170.17
166.65, 165.67
40.45
170.26
166.26
41.34
166.43
40.42
144.44
130.84
127.86
126.94
133.98
149.15
112.36
111.67
–
–
–
–
–
CH2
NCH
143.95
131.43
127.32
126.34
132.68
148.23
112.26
111.12
144.92
131.74
128.35
127.35
133.71
149.15
113.29
112.15
144.98
131.38
128.35
127.32
134.03
149.15
113.56
112.15
144.90
131.43
128.26
127.15
133.80
149.50
113.20
111.93
139.03
C(1)
C(2)
C(3)
C(4)
C(2ꢁ)
C(3ꢁ)
C(4ꢁ)
C(5ꢁ)
136.82
136.74
136.69
aThe spectra were recorded in DMSO-d6.

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FURFURYLIDENE(N-BENZOYL)GLYCYL HYDRAZONES
191
O
R
Cl
O
N
N
N
M
X
O
N
R
O
(a)
O
N
N
R
M
O
O
N
R
N
O
(b)
OH2
O
R
R
O
N
N
M
N
O
N
OH2
(c)
O
Figure 7. Proposed structures of the complexes a) M = Mn, Cu, Zn, Cd, Hg; X = OH2;
M = Ni; X = Cl, b) M = Co, and c) M = Co, Ni, Cu.
EXPERIMENTAL
Materials
All the chemicals used in the present study were of BDH grade or of
equivalent quality. Furfurylidene(N-benzoyl)glycine hydrazone was prepared by

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192
LONIBALA ET AL.
refluxing solutions of N-benzoylglycyl hydrazide (5.38 g, ∼25 mmol in 50 mL of
absolute alcohol) and furfural (2.30 g, ∼40 mmol in 25 mL of absolute alcohol) for
4 h. The brown precipitate obtained on slow cooling of the reaction mixture was
filtered, washed repeatedly with cold ethanol, and dried at room temperature. The
product obtained on recrystallizing from hot ethanol yielded light brown crystals.
Preparation of the Complexes
Chloroaquobisfurfurylidene(N-benzoyl)glycyl Hydrazone]metal(II)
Chloride, [M(FBzGH)2Cl(H2O)]Cl (M = Mn, Cu, Zn, Cd and Hg), Bis[furfur-
ylidene(N-benzoyl)glycylhydrazone]cobalt(II)DichlorideHydrate, [Co(FBz-
GH)2]Cl2 · H2O, andDichloro-bis(furfurylidene(N-benzoyl)glycylHydrazone)
nickel(II) Hydrate, [Ni(FBzGH)2Cl2] H2O. These compounds were prepared
by mixing together solutions of the metal chloride (0.50 g, 1.0 mmol in 10 mL
of ethanol) and FBzGH (1.0 g, 2.0 mmol in 20 mL of acetonitrile) and refluxing
the reaction mixture for 1 h. The precipitation was initiated by adding ∼20 mL of
tetrahydrofuran to the reaction mixture.
Bis(furfurylidene(N-benzoyl)glycylhydrazonato)diaquometal(II), [M
(FBzG)2(H2O)2] (M = Co, Ni and Cu)]. These compounds were prepared
by mixing aqueous solutions of the metal chloride (0.5 g, 1.0 mmol in 10 mL)
and the sodium salt of FBzGH (1.0 g, 2.0 mmol in 20 mL) and adjusting the pH
of the reaction mixture to ∼7 by the controlled addition of aqueous NaOH. The
precipitates were formed immediately after mixing and were digested on a water
bath for 0.5 h.
Preparation of the Solutions for the Determination
of the Formation Constants
Allofthesolutionsusedinthedeterminationoftheformationconstantsofthe
complexes were prepared in deionized water. The metal ion–ligand ratio was 1:5
and the ionic strength was adjusted with KNO3. The titrations were performed over
the pH range 2.5–11.5 with KOH solution. All titration solutions were thermostated
at the desired temperatures.
Physical Measurements
The metal ions were determined following the standard procedures (27).
Chloride was estimated gravimetrically as AgCl while hydrazine was determined

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FURFURYLIDENE(N-BENZOYL)GLYCYL HYDRAZONES
193
volumetrically by titrating against KIO3 after subjecting the complex to acid hy-
drolysis. C, H, N were microanalysed. The C, H, N microanalyses were done on
a Perkin-Elmer model 240C. Molar conductances were measured at room tem-
perature on a WTW conductivitymeter. The room temperature magnetic suscepti-
bility measurements were carried out using a Cahn–Faraday electrobalance using
Hg[Co(NCS)4] as a calibrant. IR spectra were recorded on a Perkin-Elmer model-
783 spectrophotometer while the electronic absorption spectra were recorded on
a Cary-14 spectrophotometer in Nujol. The mass spectrum was recorded on a
Varian Mat CH-7 mass spectrometer. The pH-metric titrations were performed
with a Model 335 Systronic digital pH-meter with a glass electrode (pH range
0–14) and a saturated calomel electrode, which is attached to a thermostat of cir-
cular D8-G Haake Mess Technik. The ESR spectra were obtained at 77 K on a
Varian E-line X band ESR spectrometer, using TCNE as a g-marker. The NMR
spectra were recorded on a Jeol FX-90Q multinuclear NMR spectrometer.
ACKNOWLEDGMENTS
The authors thank the Heads, Departments of Chemistry, Banaras Hindu
University and Manipur University for providing laboratory facilities. RKL and
NID acknowledge the University Grants Commission and the Council of Scientific
& Industrial Research, New Delhi, respectively, for financial assistance.
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Received March 23, 2000
Accepted November 9, 2000
Referee I: M. H. Dickman
Referee II: C. J. Carrano

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