Synthesis and spectral investigation of manganese(II), cadmium(II) and oxovanadium(IV) complexes with 2,6-diacetylpyridine bis(2-aminobenzoylhydrazone): Crystal structure of manganese(II) and cadmium(II) complexes

Article abstract of DOI:10.1016/j.ica.2006.03.009

The chelating behavior of 2,6-diacetylpyridine bis(2-aminobenzoylhydrazone) (H₂dapa) towards manganese(II), cadmium(II) and oxovanadium(IV) ions has been studied by elemental analyses, conductance measurements, magnetic properties and spectral

Full text of DOI:10.1016/j.ica.2006.03.009

Inorganica Chimica Acta 359 (2006) 3229–3236
www.elsevier.com/locate/ica
Synthesis and spectral investigation of manganese(II), cadmium(II) and
oxovanadium(IV) complexes with 2,6-diacetylpyridine
bis(2-aminobenzoylhydrazone): Crystal structure of manganese(II)
and cadmium(II) complexes
a,
a
a
a
Kalagouda B. Gudasi *, Siddappa A. Patil , Ramesh S. Vadavi , Rashmi V. Shenoy ,
b
c
Munirathinam Nethaji , Sim Wan Annie Bligh
a
Department of Chemistry, Karnatak University, Pavate Nagar, Dharwad, Karnataka 580 003, India
Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore 560 012, India
b
c
Institute for Health Research and Policy, London Metropolitan University, London N7 8DB, UK
Received 26 December 2005; received in revised form 3 March 2006; accepted 3 March 2006
Available online 17 March 2006
Abstract
The chelating behavior of 2,6-diacetylpyridine bis(2-aminobenzoylhydrazone) (H2dapa) towards manganese(II), cadmium(II) and
1
oxovanadium(IV) ions has been studied by elemental analyses, conductance measurements, magnetic properties and spectral (IR, H
NMR, UV–Vis and EPR) studies. The IR spectral studies suggest the pentadentate nature of the ligand with pyridine nitrogen, two
azomethine nitrogens and two carbonyl oxygen atoms as the ligating sites. Six coordinate structure for [VO(H2dapa)]SO4 Æ H2O and
seven coordinate structures for [Mn(H2dapa)(Cl)(H2O)]Cl Æ 2H2O and [Cd(H2dapa)Cl2] Æ H2O complexes have been proposed. Pentago-
nal bipyramidal geometry for [Mn(H2dapa)(Cl)(H2O)]Cl Æ 2H2O and [Cd(H2dapa)(Cl2)] Æ H2O complexes was confirmed by single crystal
analysis. The X-band EPR spectra of the oxovanadium(IV) and manganese(II) complexes in the polycrystalline state at room (300 K)
and also at liquid nitrogen temperature (77 K) were recorded and their salient features are reported.
ꢀ 2006 Elsevier B.V. All rights reserved.
Keywords: 2,6-Diacetylpyridine bis(2-aminobenzoylhydrazone); Transition metal compounds; Spectra; X-ray structures
1. Introduction
have adopted pentagonal bipyramidal geometry on coordi-
nation with transition metal ions [2,3]. However, the nature
of coordination depends also on the metal ion, pH of the
medium, reaction conditions and also nature of the hydra-
zone [4,5]. The ligating diversity of this class of ligands is
multiplied by their presence in protonated, deprotonated
or even partially protonated forms, e.g. 2,6-diacetylpyri-
dine bis(semicarbazone) has coordinated to tin(IV) in
protonated form [3], while 2,6-diacetylpyridine bis(2-
Hydrazones are of interest, because of their versatility in
coordinating to metals, flexibility in assuming different con-
formations, pharmacological activity and their use in ana-
lytical methods. They can coordinate either in the neutral
or in the anionic form. Furthermore the possibility of tau-
tomerism makes their study extremely interesting [1].
The chelating properties of 2,6-diacetylpyridine
bis(hydrazones) have been investigated towards several
metal ions. Various 2,6-diacetylpyridine bis(hydrazones)
thenoylhydrazone)
and
2,6-diacetylpyridine
bis(2-
furanoylhydrazone) have bound to tin(IV) in deprotonated
and partially protonated forms, respectively [6,7].
With the aim of obtaining information about the chem-
ical and structural properties of the metal complexes, espe-
cially with regard to the stereochemistry and the effects of
*
Corresponding author. Tel.: +91 836 2460129 (Res.), +91 836 2215286
(Off.); fax: +91 836 2771275.
E-mail address: kbgudasi@rediffmail.com (K.B. Gudasi).
0020-1693/$ - see front matter ꢀ 2006 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2006.03.009

3230
K.B. Gudasi et al. / Inorganica Chimica Acta 359 (2006) 3229–3236
the coordination on the conformation of the hydrazone, we
have undertaken the study of manganese(II), cadmium(II)
and oxovanadium(IV) complexes of 2,6-diacetylpyridine
bis(2-amonobenzoylhydrazone). The earlier study on this
ligand reports pentadentate or quinquidentate behavior [8].
‘g’ (g = 2.0027) marker at room temperature and also at
liquid nitrogen temperature.
2.3. X-ray crystallography
Crystals suitable for X-ray studies were grown by slow
evaporation technique from EtOH solution of the com-
plexes. Crystal data were collected on a Bruker SMART
APEX CCD diffractometer, experimental details and
refinement results are listed in Table 4. All the hydrogen
atoms were geometrically fixed and allowed to ride with
the respective light atoms to which they are attached. The
data were corrected for absorption using the program SAD-
ABS available in the BRUKER system of programs [10] and
the structures were refined by full-matrix least-squares on
all measured F 2o with SHELXL-97 [11].
2. Experimental
2.1. Reagents
All the solvents used were of analytical grade and were
used without further purification. Methyl anthranilate
and hydrazine hydrate were obtained from S.D. Fine
Chem. Ltd. 2,6-Diacetylpyridine was procured from Corey
organic limited, Hyderabad and was used without further
purification. 2-Aminobenzoylhydrazide was prepared by
known method [9].
2.4. Synthesis
2.2. Instrumentation and measurements
2.4.1. Synthesis of 2,6-diacetylpyridine bis(2-
aminobenzoylhydrazone) (H2dapa)
The ligand H2dapa was prepared by the known method
[8] with a slight modification as given below.
The metal content of the complexes was determined by
EDTA titration after decomposition with a mixture of
HCl and HClO4. The chloride and sulfate content of the
complexes were determined as silver chloride and barium
sulfate gravimetrically. The carbon, hydrogen and nitrogen
contents in each sample were determined using Heraus C H
N rapid analyzer. IR spectra in the 4000–400 cmꢀ1 range
were measured with Thermo Nicolet 320 FT-IR spectrom-
A solution of 2,6-diacetylpyridine (6.52 g, 40 mmol) in
100 ml of EtOH was added to a solution of 2-amin-
obenzoylhydrazide (12.09 g, 80 mmol) in 100 ml of the
same solvent, upon which the solution was refluxed for
2 h. A pale yellow microcrystalline product (yield 95%)
was isolated on cooling and standing overnight. The prod-
uct was recrystallized from MeOH and attempts to obtain
X-ray quality crystals of this compound were unsuccessful.
The purity of the ligand was checked by TLC. The syn-
thetic route of H2dapa is given in Scheme 1 with atom
numbering.
1
eter using KBr discs. H NMR spectra were recorded in
dmso-d6 as the solvent at 400 MHz with a BRUKER
AMX 400 spectrometer using tetramethylsilane (TMS) as
an internal reference. Electronic spectra of the complexes
were recorded with a Varian CARY 50 Bio UV–Vis spec-
trometer. The magnetic susceptibility measurements were
carried out with a Faraday balance using Hg[Co(NCS)4]
as the calibrant and diamagnetic corrections were made
by direct weighing of the ligand for diamagnetic pull.
Conductance measurements were recorded in DMSO
(10ꢀ3 M) using Elico conductivity bridge type CM-82, pro-
vided with a dip type conductivity cell fitted with platinum
electrodes. EPR spectra were recorded on Varian E-4 X-
band spectrometer using tetracyanoethylene (TCNE) as
2.4.2. Synthesis of metal complexes
Manganese(II), cadmium(II) and oxovanadium(IV)
complexes were prepared by mixing a hot chloroform solu-
tion (5 ml) of H2dapa (0.859 g; 2 mmol) and ethanolic solu-
tion (5 ml) of the corresponding metal salt (2 mmol). The
solution was refluxed for 1 h and then allowed to stand.
The slow evaporation of this resulted in to a microcrystalline
O
C
4
3
3
2
NH2
6
H3C
6
CH3
2
N
Reflux in ethanol
2 h
CH3
5
5
H3C
+ 2
H
N
1
C
C
C
O
C
N
NH2
N2
2
N
O
HN3
NH
3
7
13
10
C
7
O
C
O
13
12
11
12
11
8
8
9
9
H N
2 4
NH2
4
10
Scheme 1. Synthetic route of the ligand (H2dapa).

K.B. Gudasi et al. / Inorganica Chimica Acta 359 (2006) 3229–3236
3231
product with yield varying in the 85–90% range. X-ray qual-
ity crystals of manganese(II) and cadmium(II) complexes
were grown by slow evaporation technique.
plexation this band has shifted to lower wavelength, sug-
gesting the coordination of azomethine nitrogen [14].
Absorptions at 809 and 601 nm observed in the elec-
tronic spectrum of the oxovanadium(IV) complex, can be
assigned to b2 ! e and b2 ! b1 transitions, respectively.
The high energy b2 ! a1 transition was not observed. It
might have been obscured in the broad charge transfer
band, which sets in at about 357–333 nm, in distorted octa-
hedral geometry around VO(IV) ion [15].
3. Results and discussion
Some physical data for H2dapa and its metal complexes
are given in Table 1. Elemental analyses establish 1:1
(metal:ligand) stoichiometry for the present complexes.
Molar conductance values indicate 1:1 electrolytic nature
for manganese(II) and oxovanadium(IV) complexes and
non-electrolytic nature for cadmium(II) complex. All the
complexes are insoluble in common organic solvents, but
soluble in EtOH, DMF and DMSO solvents.
In case of manganese(II) and cadmium(II) complexes
the d5 and d10 configurations account for the absence of
d–d bands.
3.2. Infrared spectra
3.1. Magnetic and electronic spectral studies
Comparison of the main vibrational bands of H2dapa in
its uncoordinated state and in the coordinated form is used
to establish its ligating behavior and the data is compiled in
Table 2.
Magnetic and electronic spectral data are summarized in
Table 1. The observed effective magnetic moment (leff) of
oxovanadium(IV) complex is 1.86 BM, which is in good
agreement with a d1 system and is consistent with a mono-
nuclear distorted octahedral structure [12]. The observed
The bands at 3448 and 3357 cmꢀ1 in the infrared spec-
trum of the ligand may be assigned to the mas(HNH) and
ms(HNH) vibrations of NH2 groups and the band at
3273 cmꢀ1 to m(NH) group of the ligand. The persistence
of these bands in the spectra of all the complexes indicate
the non-involvement of these groups in coordination [16].
The bands at 1671, 1550, and 1262 cmꢀ1 assigned to
amide-I [m(C@O)], amide-II [m(CN) + m(NH)] and amide-
III [m(NH) + m(CN)] vibrations, respectively, have suffered
leff value (5.93 BM) for the present manganese(II) complex
confirms the high spin complex with five unpaired elec-
trons. Cadmium(II) complex is diamagnetic as expected
for d10 configuration [13].
Electronic spectrum of ligand showed a band at 390 nm
due to the n ! p* transition of azomethine group. On com-
Table 1
Physical, analytical, magnetic moments, electronic spectral data and molar conductance data of the compounds
Compound
M.p. (ꢁC) Elemental analysis: found (calculated) (%)
Km
(Xꢀ1 cm2 (BM) (nm)
molꢀ1
leff
kmax
M
C
H
N
Clꢀ=SO4
2ꢀ
)
H2dapa
187
64.45 (64.34) 5.42 (5.35) 22.92 (22.83)
10.83 (10.52) 46.85 (46.73) 4.61 (4.56) 16.42 (16.58) 11.73 (11.80) 46.20
17.87 (17.89) 43.72 (43.80) 3.83 (3.96) 15.67 (15.54) 11.00 (11.09) 1.78
10.86 (10.97) 45.31 (45.26) 4.03 (4.09) 16.08 (16.06) 15.82 (15.74) 43.72
390
366
368
809, 601,
357–333
[Mn(H2dapa)(Cl)(H2O)]Cl Æ 2H2O >250
[Cd(H2dapa)(Cl2)] Æ H2O
[VO(H2dapa)]SO4 Æ H2O
5.89
Dia
1.86
>250
>250
Dia = diamagnetic.
Table 2
Infrared spectral bands (cmꢀ1) and their assignments in H2dapa and its metal complexes
H2dapa
[Mn(H2dapa)(Cl)(H2O)]Cl Æ 2H2O
[Cd(H2dapa)(Cl2)] Æ H2O
[VO(H2dapa)]SO4 Æ H2O
Assignment
3550 b
3447 m
3310 m
3169 sh
1626 s
1585 s
1514 s
1250 s
1550 s
1476 m
1449 m
1012 m
3545 b
3465 m
3340 s
3218 sh
1630 s
1582 s
1518 s
1244 s
1549 s
1477
3500 b
3430 w
3333 w
3185 sh
1616 m
1562 w
1511 s
1254 s
1562 s
1470 m
1453 m
1022 sh
m(H2O) band vibration
ma(NH2) band vibration
ms(NH2) band vibration
m(NH) band vibration
amide(I) band vibration
m(C@N) vibration
amide(II) band vibration
amide(III) band vibration
pyridine ring stretching vibrations
3448 w
3357 s
3273 w
1671 s
1616 w
1550 s
1262 s
1588 s
1486 m
1453 m
990 m
1451 m
1010 m
pyridine ring breathing band
Abbreviations: s, strong; m, medium; b, broad; sh, shoulder; w, weak; m(V@O) = 980 cmꢀ1
.

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K.B. Gudasi et al. / Inorganica Chimica Acta 359 (2006) 3229–3236
a negative shift in the spectra of all the complexes by about
35–20 cmꢀ1, indicating the participation of uncharged
amide oxygen in coordination [17].
The absorption due to m(C@N) in the free ligand is
observed at 1616 cmꢀ1 and has shifted to lower wave num-
ber (ꢁ1585–1548 cmꢀ1) in all the complexes, indicating
coordination of the ligand through azomethine nitrogen
[18].
protons of pyridine moiety, respectively. Two doublets,
one triplet and a multiplet appearing at 7.61 [C13H], 6.80
[C10H], 6.62 [C12H] and 7.23 ppm [C11H] are attributed
to eight aromatic protons of 2-aminobenzoylhydrazide
moiety.
In cadmium(II) complex, the signals due to N3H and
N4H2 appeared at the same position as in the ligand
(10.64 and 6.24 ppm, respectively), indicating the non-
involvement of NH2 group in coordination. The triplet
[C4H] and doublet [C3H] have merged into a broad signal
and shifted to 8.22 ppm. This change along with the shift of
the band due to C6H3 groups [2.63 ppm] suggest the
involvement of pyridine nitrogen and azomethine nitrogens
in coordination [22]. The broad bands of eight aromatic
protons of 2-aminobenzoylhydrazide moiety appear at
the same position as in the ligand.
The bands in the ligand spectrum at 1588, 1486,
1453 cmꢀ1 were assigned to pyridine ring stretching vibra-
tions. The shift of these bands in the spectra of complexes
supports the coordination of pyridine nitrogen to the metal
ion. The ring-breathing mode observed at 990 cmꢀ1 in the
free ligand disappear in the complexes and is replaced by a
band at 1010–1022 cmꢀ1. This shift is also indicative of
coordination of pyridine nitrogen with metal ion [19].
In [VO(H2dapa)]SO4 Æ H2O, the strong non-ligand band
observed in the region ꢁ980 cmꢀ1 is assigned to m(V@O)
[20]. The bands in the region 1115 and 610 cmꢀ1 confirm
presence of ionic sulfate. Free sulfate ion belongs to the
Td point group and is expected to show only two funda-
mental IR active vibrations m3(F2); i.e. md(S–O), and
m4(F2), i.e. dd(O–S–O) [21].
3.4. EPR studies
The EPR spectra of VO2+ polycrystalline sample at
room temperature and at liquid nitrogen temperature exhi-
bit an eight-line pattern corresponding to the usual parallel
and perpendicular components of g and hyperfine (hf) A-
tensor. The EPR spectrum of VO2+ polycrystalline sample
at room temperature is shown in Fig. 1.
A broad band in the region 3500–3200 cmꢀ1 indicates
the presence of lattice held water molecule/s in all the com-
plexes [17].
In an octahedral ligand field for d1-VO(IV) complex, the
2
ground state is T2g. Owing to the spin-orbit coupling, the
1
3.3. H NMR spectral studies
degenerate 2T2g state may further split by distortion, e.g. by
Jahn–Teller effects or by a tetragonal ligand field, in to 2Eg
1H NMR spectra of H2dapa and its cadmium(II) com-
plex were recorded in DMSO-d6 solvent and the data along
with the assignments are included in Table 3. Scheme 1
shows numbering system of H2dapa. Only one set of sig-
nals were observed for the ligand and its cadmium(II) com-
plex indicating that the two arms of the ligand in its
uncoordinated state as well as in coordinated form are
magnetically equivalent in solution on the corresponding
NMR time scale.
The spectrum of H2dapa exhibits three singlets at 10.64,
6.24 and 2.54 ppm, which are due to the N3H, N4H2 and
C6H3 protons, respectively. A triplet at 7.91 [C4H] and
doublet at 8.10 ppm [C3H] corresponds to one and two
and B2g levels. Kivelson and Lee have theoretically pre-
2
dicted a value of 170 cmꢀ1 for k (spin-orbit coupling con-
stant) for C4v-symmetry [23]. The k value in the present
oxovanadium(IV) complex (63.72 cmꢀ1) is within the rea-
sonable limits of predicted value. The reduction in k value
for the VO2+ ion in this complex can be accounted in terms
of the structural nature of the compound. The spectral
parameter values for the VOIV complex [gi = 1.992,
g^ = 2.02, g = 2.01, Ai = ꢀ107.14, A^ = ꢀ35, A (G) =
ꢂ
ꢂ
ꢀ55.713] are consistent with the reported values for struc-
turally analogous oxovanadium(IV) Schiff bases which
have a slightly distorted octahedral environment with the
unpaired electron occupying predominantly the b2 level
in the ground state [24].
The EPR spectra of manganese(II) complex in polycrys-
talline state at room temperature and liquid nitrogen tem-
perature exhibit a broad isotropic signal centered at 2.0,
which is equal to the free electron g-value (g = 2.0027).
The broadening of the spectrum is due to spin relaxation
[25].
Table 3
1H NMR spectral data of H2dapa and its cadmium(II) complex
Chemical shifts in d (ppm)
Protons
H2dapa
Cadmium(II) complexa
N3H
N4H2
C6H3
C4H
C3H
C13H
C12H
C11H
C10H
a
10.64 (s, 2H)
6.24 (s, 4H)
2.54 (s, 6H)
7.21 (t, 1H, J = 7.60 Hz)
8.10 (d, 2H, J = 7.72 Hz)
7.61 (d, 2H, J = 7.68 Hz)
6.62 (t, 2H, J = 7.20 Hz)
7.23 (m, 2H)
10.64
6.24
2.54
8.22
8.22
7.61
6.62
7.23
6.80
3.5. X-ray crystal structure determinations
3.5.1. Crystal structural description of
[Mn(H2dapa)(Cl)(H2O)]Cl Æ 2H2O
Crystal data collection and refinement of [Mn(H2da-
pa)(Cl)(H2O)]Cl Æ 2H2O is summarized in Table 4. The crys-
tal structure consists of cation [Mn(H2dapa)(Cl)(H2O)]+,
6.80 (d, 2H, J = 8.2 Hz)
Due to the poor solubility, splitting pattern was not clearly observed.

K.B. Gudasi et al. / Inorganica Chimica Acta 359 (2006) 3229–3236
3233
Fig. 1. EPR spectrum of complex [VO(H2dapa)]SO4 Æ H2O at room temperature.
Table 4
Crystal data and structural refinement for [Mn(H2dapa)(Cl)(H2O)]Cl Æ 2H2O and [Cd(H2dapa)(Cl2)] Æ H2O
[Mn(H2dapa)(Cl)(H2O)]Cl Æ 2H2O
[Cd(H2dapa)(Cl2)] Æ H2O
Compound
C
23H27Cl2MnN705
C23H27Cl2CdN704
257383
648.817
pale yellow/rectangular
293(2)
CCDC number
Molecular mass
Colour/shape
T (K)
257382
609.37
purple/rectangular
293(2)
Crystal system
Space group
a (A)
triclinic
P1
tetragonal
P42/n
10.368(3)
10.368(3)
23.498(1)
90.00
˚
9.780(7)
11.983(9)
12.256(9)
108.282(12)
˚
b (A)
˚
c (A)
b (ꢁ)
3
˚
V (A )
1297.2(17)
2526(2)
Z
2.00
1.560
4.00
1.706
Dcalc (g cmꢀ3
Index ranges
F(000)
)
ꢀ12 6 h 6 12, ꢀ14 6 k 6 13, ꢀ15 6 l 6 15
ꢀ13 6 h 6 13, ꢀ13 6 k 6 12, ꢀ29 6 l 6 29
630
0.764
Mo Ka
0.71073
1312
1.22
Mo Ka
0.71073
Absorption coefficient (mmꢀ1
Radiation
)
˚
Wavelength (A)
Reflection collected
8723
19803
Independent reflections (Rint
Tmax and Tmin
Crystal size (mm)
Number of parameters
Goodness-of-fit
)
4874 (0.0307)
0.9527 and 0.8272
0.26 · 0.14 · 0.06
351
2740 (0.0260)
0.9347 and 0.8176
0.19 · 0.11 · 0.06
223
1.006
1.061
Final R indices [I > 2r(I)]
R1 = 0.0796, wR2 = 0.2060
R1 = 0.1164, wR2 = 0.2284
0.870 and ꢀ0.540
R1 = 0.0270, wR2 = 0.0618
R1 = 0.0366, wR2 = 0.0661
0.423 and ꢀ0.245
ꢀ3
˚
Largest difference in peak and hole (e A
)
chloride anion and two lattice held water molecules. The
ORTEP and molecular packing diagrams are displayed in
Figs. 2 and 3. The selected bond lengths and angles are
given in Table 5 and possible hydrogen bonds are listed in
Table 6.
It can be seen that the [Mn(H2dapa)(Cl)(H2O)]-
Cl Æ 2H2O complex is seven coordinate and has pentagonal
bipyramidal (PBP) structure. The dapa acts as a quinqued-
entate ligand coordinating through three nitrogen [N(1),
N(2) and N(5)] and two oxygen [O(1) and O(2)] atoms,
encircling the manganese ion and occupying the equatorial
belt. The apices of the bipyramid are filled by a chloride ion
and the oxygen atom from the water molecule. Previously,
similar cationic heptacoordinated complexes with pentago-
nal bipyramidal geometry have been reported by Pelizzi
et al. [8] and Palenik and Wester [26].

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K.B. Gudasi et al. / Inorganica Chimica Acta 359 (2006) 3229–3236
Table 5
Selected bond lengths (A) and bond angles (ꢁ) for [Mn(H2dapa)(Cl)-
˚
(H2O)]Cl Æ 2H2O and [Cd(H2dapa)(Cl2)] Æ H2O complexes
[Mn(H2dapa)(Cl)(H2O)]Cl Æ 2H2O [Cd(H2dapa)(Cl2)] Æ H2O
Bond lengths
Mn(1)–O(2)
Mn(1)–O(1)
Mn(1)–N(1)
Mn(1)–N(2)
Mn(1)–O(10)
Mn(1)–N(5)
Mn(1)–Cl(1)
N(5)–C(17)
N(2)–C(2)
Bond lengths
2.178(4) Cd(1)–O(1)
2.192(4) Cd(1)–O(1)
2.252(5) Cd(1)–N(1)
2.254(5) Cd(1)–N(2)
2.261(5) Cd(1)–Cl(1)
2.284(5) Cd(1)–N(2_2)
2.493(3) Cd(1)–Cl(1_2)
1.269(7) N(2)–C(2)
2.369(17)
2.369(17)
2.362(3)
2.399(18)
2.598(10)
2.399(18)
2.598(10)
1.278(3)
1.278(3)
1.234(3)
1.234(3)
1.263(8) N(2_2)–C(2_2)
1.218(7) O(1)–C(3)
1.227(7) O(1_2)–C(3_2)
O(2)–C(16)
O(1)–C(3)
Bond angles
Bond angles
O(2)–Mn(1)–O(1)
O(1)–Mn(1)–N(2)
N(1)–Mn(1)–N(2)
N(1) Mn(1)–N(5)
O(2)–Mn(1)–N(5)
O(10)–Mn(1)–Cl(1)
84.00(16) O(1_2)–Cd–O(1)
69.16(16) (O1)–Cd(1)–N(2)
68.69(18) N(1)–Cd(1)–N(2)
68.40(18) N(1)–Cd(1)–N(2_2)
68.49(17) (O1_2)–Cd(1)–N(2_2)
176.53(12) Cl(1)–Cd(1)–Cl(1_2)
94.59(8)
66.35(6)
66.58(4)
66.58(4)
66.35(6)
173.35(2)
Fig. 2. ORTEP representation of the complex [Mn(H2dapa)(Cl)(H2O)]Cl Æ
2H2O with labeling of the atoms.
plexes [8,26]. The bond distances N(5)–C(17) 1.269(7),
N(2)–C(2) 1.263(8), O(1)–C(3) 1.227(7) and O(2)–C(16)
˚
1.218(7) A are indicative of double bonds. The C–C–C
bond angles in aromatic rings are around 120ꢁ with the var-
iation being less than 2ꢁ, which is characteristic of sp2-
hybridized carbons. The bond angles in the pentagonal
base O(1)–Mn(1)–N(2) 69.16(16)ꢁ, N(1)–Mn(1)–N(2)
68.69(18)ꢁ, N(1)–Mn(1)–N(5) 68.40(18)ꢁ, O(2)–Mn(1)–
N(5) 68.49(17)ꢁ are quite close to the ideal 72ꢁ (ideal pen-
tagonal bipyramidal geometry), while the angle involving
the two oxygen atoms O(2)–Mn(1)–O(1) is considerably
greater [84.00(16)ꢁ] and these angles are also in good agree-
ment with the bond angles found in [Mn(H2dapab)
(CH3OH)Cl]Cl Æ 2H2O and [Mn(DAPSC)(H2O)Cl]Cl Æ
2H2O complexes, suggests similar ONNNO donor proper-
ties in both ligands [8,26].
The molecule is coplanar. Mn(1) atom lies 0.144(6)ꢁ
above the N3O2[N(1), N(2), N(5), O(1) and O(2)] basal
set of atoms. Plane I [N(1), C(1), C(21), C(20), C(19),
C(18)] forms a dihedral angle of 8.71(1)ꢁ with plane II
[C(10), C(11), C(12), C(13), C(14), C(15), N(7)], 15.09(1)ꢁ
with plane III [C(4), C(9), C(8), C(7), C(6), C(5), N(4)],
2.65(2)ꢁ with plane IV [N(1), N(2), N(5), O(1), O(2),
Mn(1)]. While plane II form dihedral angles of 7.05(2)ꢁ
and 6.61(1)ꢁ with planes III and IV, respectively. Plane
III forms a dihedral angle of 12.57(1)ꢁ with plane IV. In
the molecular packing, pairs of [Mn(dapa)(Cl)(H2O)]-
Cl Æ 2H2O are observed. These pairs are built by intermo-
lecular hydrogen bonding through the proton from
coordinated water molecules [O(10)H(101)H(102)], the
anions [Cl(3)], the lattice held water molecules
[O(3)H(31A)H(31B) and O(4)H(41A)H(41B)] and the
coordinated chloride molecules [Cl(1)]. Two NH2
[N(7)H(7A)H(7B) and N(4)H(4A)H(H4B)] groups present
Fig. 3. The crystal packing of complex [Mn(H2dapa)(Cl)(H2O)]Cl Æ 2H2O
viewed along the most representative direction.
The C–C bond distances in aromatic rings are in the
˚
normal range of 1.33–1.46 A, which is characteristic of
delocalised aromatic rings. The bond distances Mn(1)–
N(1) 2.252(5), Mn(1)–N(2) 2.254(5), Mn(1)–N(5)
2.284(5), Mn(1)–O(1) 2.192(4), Mn(1)–O(2) 2.178(4),
˚
Mn(1)–Cl(1) 2.493(3) and Mn(1)–O(10) 2.261(5) A are in
good agreement with the bond distances found in similar
seven coordinated pentagonal bipyramidal Mn(II) com-

K.B. Gudasi et al. / Inorganica Chimica Acta 359 (2006) 3229–3236
3235
Table 6
Hydrogen bonds for [Mn(H2dapa)(Cl)(H2O)]Cl Æ 2H2O and [Cd(H2dapa)(Cl2)] Æ H2O
˚
˚
˚
D–Hꢃ ꢃ ꢃA
D–H (A)
Hꢃ ꢃ ꢃA (A)
Dꢃ ꢃ ꢃA (A)
\D–Hꢃ ꢃ ꢃA (ꢁ)
Manganese(II) complex
O(10)–H(101)ꢃ ꢃ ꢃCl(1)i
O(3)–H(31B)ꢃ ꢃ ꢃCl(1)i
O(4)–H(41B)ꢃ ꢃ ꢃCl(3)i
N(4)–H(4B)ꢃ ꢃ ꢃO(1)i
N(7)–H(7B)ꢃ ꢃ ꢃO(2)i
C(9)–H(9)ꢃ ꢃ ꢃO(3)ii
0.993(5)
1.185(8)
1.042(1)
0.860(5)
0.860(7)
0.930(8)
0.860(5)
1.069(1)
0.960(6)
1.124(1)
0.860(7)
2.136(2)
2.065(2)
2.265(2)
2.011(5)
1.985(5)
2.500(1)
2.437(1)
1.964(1)
2.322(8)
2.007(1)
2.166(5)
3.121(5)
3.221(7)
3.250(11)
2.639(8)
2.618(9)
3.281(4)
3.275(1)
2.974(1)
3.116(1)
2.974(1)
3.015(9)
170.77(3)
164.28(5)
157.10(6)
129.06(5)
129.46(5)
141.75(5)
164.82(4)
156.42(6)
139.55(5)
142.01(7)
169.12(5)
N(3)–H(3)ꢃ ꢃ ꢃO(3)ii
O(4)–H(41A)ꢃ ꢃ ꢃO(3)ii
C(22)–H(22C)ꢃ ꢃ ꢃO(3)ii
O(3)–H(31A)ꢃ ꢃ ꢃO(4)ii
N(4)–H(4A)ꢃ ꢃ ꢃO(10)iii
Cadmium(II) complex
N(4)–H(4)ꢃ ꢃ ꢃO(1)i
0.820(0.036)
0.944(0.028)
0.779(0.034)
0.813(0.033)
0.777(0.035)
2.037(0.033)
2.255(0.027)
2.538(0.033)
2.486(0.33)
2.440(0.035)
2.666(0.003)
3.173(0.004)
3.288(0.004)
3.295(0.0025)
3.215(0.003)
133.05(3.08)
163.83(2.34)
162.16(3.19)
172.85(3.07)
175.89(3.44)
C(9)–H(9)ꢃ ꢃ ꢃO(2)i
C(22)–H(22A)ꢃ ꢃ ꢃO(2)i
O(2)–H(2A)ꢃ ꢃ ꢃCl(1)ii
O(2)–H(2B)ꢃ ꢃ ꢃCl(1)iii
Symmetry transformations used to generate equivalent atoms: (i) x, y, z, (ii) ꢀx + 1, ꢀy + 1, ꢀz + 1, (iii) ꢀx + 1, ꢀy, ꢀz + 1; and (i) x, y, z, (ii) x + y ꢀ 1,
z, (iii) ꢀx + 1, ꢀy + 2, ꢀz.
in the complex are syn to CO [C(3)O(1) and C(16)O(2)]
groups and each hydrogen atom of NH2 group are engaged
in intramolecular hydrogen bonding with each oxygen
atom of CO groups.
3.5.2. Crystal structural description of
[Cd(H2dapa)(Cl2)] Æ H2O
Crystal data collection and refinement of [Cd(H2dapa)-
(Cl2)] Æ H2O is summarized in Table 4. The molecular struc-
ture (ORTEP) of the neutral cadmium(II) complex,
[Cd(H2dapa)(Cl2)] Æ H2O is depicted in Fig. 4. Selected
bond lengths and angles in the complex are listed in Table
5. Possible hydrogen bonds are given in Table 6.
As in the case of manganese(II) complex, a pentagonal
bipyramidal geometry around the metal is observed in cad-
mium(II) complex also. The atoms N(1), N(2), O(1),
O(1_2) and N(2_2) are occupying the equatorial belt form-
Fig. 4. ORTEP representation of the complex [Cd(H2dapa)(Cl2)] Æ H2O
ing four planar five membered chelate rings with Cl(1) and
Cl(1_2) in the axial positions. The bond lengths and angles
in Cd(II) complex reveal that, the whole molecule is sym-
metrical and hence only one set of bond distances and
angles are observed.
with labeling of the atoms.
N(1)–Cd(1)–N(2_2) 66.58(4)ꢁ, O(1)–Cd(1)–N(2) 66.35(6)ꢁ,
O(1)–Cd(1)–N(2_2) 66.35(6)ꢁ are close to the ideal 72ꢁ (ideal
pentagonal bipyramidal geometry) while the angle involving
the two oxygen atoms O(1)–Cd(1)–O(1_2) is considerably
greater [94.59(8)ꢁ] and these angles are also in good agree-
ment with the bond angles found in [Cd(H2daps)(Cl2)]CH-
Cl3 Æ CH3OH complex suggests similar ONNNO donor
properties in the ligand [27].
The molecular packing diagram of the [Cd(H2dapa)
(Cl2)] Æ H2O complex in the unit cell is illustrated in
Fig. 5. The molecule is planar. It shows the presence of four
intramolecular and six intermolecular hydrogen bonds.
Molecular packing is mainly dictated by a three-dimen-
sional hydrogen-bonding network involving cations,
The bond distances Cd(1)–N(1) 2.362(3), Cd(1)–N(2)
2.399(18), Cd(1)–N(2_2) 2.399(18), Cd(1)–O(1) 2.369(17),
Cd(1)–O(1_2) 2.369(17), Cd(1)–Cl(1) 2.598(10) and Cd(1)–
˚
Cl(1_2) 2.598(10) A are in good agreement with the bond
distances found in a similar seven coordinated complex with
pentagonal bipyramidal geometry reported by Pelizzi et al.
[27]. The bond distances N(2)–C(2) 1.278(3), N(2_2)–
C(2_2) 1.278(3), O(1)–C(3) 1.234(3) and O(1_2)–C(3_2)
˚
1.234(3) A are indicative of double bonds. The C–C–C bond
angles are around 120ꢁ with the variation being less than 3ꢁ,
which is characteristic of sp2-hybridized carbons in the pen-
tagonal base. The bond angles N(1)–Cd(1)–N(2) 66.58(4)ꢁ,

3236
K.B. Gudasi et al. / Inorganica Chimica Acta 359 (2006) 3229–3236
are also due to University Sophisticated Instrumentation
Center, Karnatak University Dharwad for carrying out ele-
mental analysis. One of the authors (S.A.P.) is thankful to
Karnatak University Dharwad for award of University Re-
search fellowship.
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Acknowledgments
Authors are thankful to Department of Inorganic and
Physical Chemistry and Sophisticated Instrumentation
Facility, Indian Institute of Science, Bangalore and Indian
Institute of Technology, Bombay for recording crystal
structures, 1H NMR spectra and EPR spectra. Thanks