Crystal Structure of Spiro 5,5-Dimethyl Cyclohexane1,2,3-trione 2-phenylhydrazone and Spectral Characterization of its Transition Metal Complexes

Article abstract of DOI:10.1080/15533170903095011

The synthesis and characterization of spiro5,5-dimethylcyclohexane1,2,3- trione2-phenylhydrazone, phenylazodimedone (AD) and the characterization of its complexes with Fe(III), Co(II), Ni(II), Cu(II) and Zn(II) have been carried out. AD was found to have the hydrazone form with intra-molecular N-HO hydrogen bond. The complexes were found to have a general formula ML₂/ML ₃ when M is a divalent/trivalent metal, respectively, and L is the mono anion of AD. The structure of AD has been arrived at by various spectral techniques and the presence of hydrogen bonding has been verified by single crystal XRD. The complexes were characterized by elemental analyses, magnetic susceptibility measurements, electronic-infrared-1HNMR and mass spectral studies.

Full text of DOI:10.1080/15533170903095011

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Crystal Structure of Spiro 5,5-Dimethyl
Cyclohexane1,2,3-trione 2-phenylhydrazone and
Spectral Characterization of its Transition Metal
Complexes
Susannah Seth a & Kuttamath Kunniyur Aravindakshan b
a Department of Chemistry , Malabar Christian College , Kozhikode, India
b Department of Chemistry , University of Calicut , India
Published online: 30 Dec 2009.
To cite this article: Susannah Seth & Kuttamath Kunniyur Aravindakshan (2009) Crystal Structure of Spiro 5,5-Dimethyl
Cyclohexane1,2,3-trione 2-phenylhydrazone and Spectral Characterization of its Transition Metal Complexes, Synthesis
and Reactivity in Inorganic, Metal-Organic, and Nano-Metal Chemistry, 39:6, 345-350
To link to this article: http://dx.doi.org/10.1080/15533170903095011
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Synthesis and Reactivity in Inorganic, Metal-Organic, and Nano-Metal Chemistry, 39:345–350, 2009
Copyright © Taylor & Francis Group, LLC
ISSN: 1553-3174 print / 1553-3182 online
DOI: 10.1080/15533170903095011
Crystal Structure of Spiro 5,5-Dimethyl
Cyclohexane1,2,3-trione 2-phenylhydrazone and Spectral
Characterization of its Transition Metal Complexes
Susannah Seth1 and Kuttamath Kunniyur Aravindakshan2
1Department of Chemistry, Malabar Christian College, Kozhikode, India
2Department of Chemistry, University of Calicut, India
EXPERIMENTAL
The synthesis and characterization of spiro5,5-dimethyl-
cyclohexane1,2,3-trione2-phenylhydrazone, phenylazodimedone
Synthesis of AD
Aniline (10 mmole, 0.93 mL) was diazotised with NaNO2
(AD) and the characterization of its complexes with Fe(III), Co(II),
Ni(II), Cu(II) and Zn(II) have been carried out. AD was found
to have the hydrazone form with intra-molecular N-H O hydro-
gen bond. The complexes were found to have a general formula
ML2/ML3 when M is a divalent/trivalent metal, respectively, and
L is the mono anion of AD. The structure of AD has been arrived at
by various spectral techniques and the presence of hydrogen bond-
ing has been verified by single crystal XRD. The complexes were
characterized by elemental analyses, magnetic susceptibility mea-
surements, electronic-infrared-1HNMR and mass spectral studies.
(10 mmole, 0.69 g) and 1:1HCl (5 mmole, 5 mL) at a tem-
perature of ∼0–5◦C. Excess acid was removed by the addition
of urea. The mixture was stirred for half an hour maintaining
the temperature at ∼ 0–5◦C. This solution of phenyl diazonium
chloride was added drop wise with stirring to a well cooled
solution of dimedone (10 mmole, 1.4 g) in ethanol when lemon-
yellow colored phenylazo dimedone (AD) precipitated out. The
pH of the solution was adjusted to about 6.5 using sodium ac-
etate. The solution was stirred for another half an hour and the
precipitate was filtered, washed with water, recrystallized from
methanol and dried over anhydrous MgSO4 in a desiccator. The
purity of the compound was checked by TLC technique (yield
2.07 g, 85%).
. . .
Keywords complexes, crystal structure, phenylazodimedone, spec-
tral characterization
INTRODUCTION
Azo betadiketones are obtained by the diazocoupling re-
action between diazonium salts and beta diketones. These
compounds exhibit keto-enol tautomerism and act as biden-
tate ligands forming chelates with metal ions. Even though
metal complexes of azodimedones with substituted phenyl
group have been reported earlier,[1] a detailed characterization
and structural specifications have been lacking. Therefore, the
present investigation has taken up focusing on the synthesis
andgeometrical features of spiro5,5-dimethylcyclohexane1,2,3-
trione2-phenylhydrazone and its Fe(III), Co(II), Ni(II), Cu(II)
and Zn(II) chelates.
Synthesis of Metal Complexes of AD
The metal salts used for the synthesis were chlorides of
Fe(III) and Zn(II) and acetates of Co(II), Ni(II) and Cu(II).
The metal to ligand ratio used was 1:2 for divalent metal com-
plexes and 1:3 for trivalent metal complexes. A methanolic so-
lution of the metal salt (1 mmole) was added slowly in drops
with stirring to a methanolic solution of phenylazodimedone (3
mmole for Fe (III) and 2 mmole for Co(II), Ni(II), Cu(II) and
Zn(II)). This mixture was refluxed for about 2 h on a steam bath.
The complex precipitated on cooling and was filtered, washed
with water and dried over anhydrous MgSO4 in a desiccator.
The complexes were recrystallised from methanol or methanol-
dichloromethane mixture.
Received 5 March 2009; accepted 13 April 2009.
The authors thank Dr. P. Mohammed Shafi, Professor and Head of
the Department of Chemistry, University of Calicut and Sophisticated
Analytical Instrument Facility (SAIF) at Kochi, Lucknow, IIT Madras
and IIT Bombay for providing physico-chemical data. Thanks are also
due to the University Grants Commission, New Delhi for financial
assistance.
Address correspondence to Susannah Seth, Dept. of Chemistry,
Malabar Christian College, Kozhikode, India. E-mail: susannahseth@
yahoo.com
Analytical Methods
The percentages of carbon,hydrogen and nitrogen were de-
termined by micro analyses using Vario EL III CHNS ana-
lyzer. Electronic spectra were recorded on a JASCO UV-visible
spectrophotometer. IR spectra were obtained as KBr discs of
the samples on JASCO FT/IR-4100 spectrophotometer. The
345

346
S. SETH AND K. K. ARAVINDAKSHAN
1HNMRspectra were taken by dissolving the sample in CDCl3 1650 cm−1. In conjugated systems it shifts to lower frequency.
on a Varian Mercury NMR instrument at 400 MHz. The ESI The band at 1590 cm−1 may be due to conjugated stretching of
mass spectra were measured using Micromass Quattro II triple C N.
quadrupole mass spectrometer. The magnetic susceptibilities
1H NMR Spectrum
were determined using Sherwood Scientific Magway magnetic
susceptibility balance. The metal percentages of the chelates
were estimated from standard analytical procedures,[2] and also
by ICP-AES method on IRIS intrepid IIX SP instrument. The
single crystal XRD was performed on Bruker AXS –Kappa
Apex instrument.
The 1H NMR spectrum supports well the hydrazone structure
of AD. In the azo form, there should be a peak corresponding to
− >CH group flanked by two >C O groups at ∼3.2–3.5 ppm,
which was absent in the 1H NMR spectrum of phenylazo dime-
done. N-H proton signal of hydrazone group was observed at
15.4 ppm, which gave additional evidence to the hydrazone
structure in which the absorption occurs at 3–5 ppm lower than
the azo-hydroxy resonance structure. In addition to the above
peaks, the unmistatablepeaks,[7] of CH3 at 1.9 ppm, CH2 at
∼2.6 ppm and aromatic pattern at ∼ 7.2–7.6 ppm were also
present.
RESULTS AND DISCUSSION
Structure of AD
Analytical Data
Phenylazodimedone has been formed according to the fol-
lowing reaction
Mass Spectrum
C6H5N+2 + C8H12O → C14H16N2O2 + H+
The mass spectrum of AD was pronounced with the presence
of base peak at m/z 245, which is the (M+1)+ ion. The other
peaks of importance are at m/z 217 [(M+1)-(C2H4)] and one
at m/z 152 [(M+1) – C6H5NH) which gives additional support
The percentages of C, H and N (found: C, 68.69;H,6.11;N,
11.29, calcd., C,11.48;H, 68.35;N, 6.56) showed close agree-
ment with the molecular formula C14H16N2O2. It registered a
sharp melting point at 120◦C.
. . .
to the hydrazone structure where HN N = cleavage occurs.
Moreover, the absence of an (M-N2)+ peak,[8] also points to the
absence of an azo group. The other specific peaks are at m/z 124
(M+1-(C6H5NH+two CH3)+, and m/z 94 (C6H5N+H3).
Spectral Data
The electronic, IR, NMR and mass spectra of the AD were
utilized to ascertain the structure.
Single Crystal XRD Data
The single crystal of the AD has been obtained by slow evap-
oration of the purified substance in CH2Cl2+ CH3OH mixture
at room temperature. The data collection was done by cutting a
suitable piece of size 0.3 × 0.2 × 0.2 mm and mounting on a go-
niometer using glass fiber. 10766 reflections were collected and
2011 were used for structure determination. The structure was
solved by direct method using SHELXL software and refined
by full matrix least squares against F2. The computer graphics
was of ORTEP model (Figure 1). The general crystal data are
tabulated in Table 1. Bond lengths between selected atoms are
included in Table 2. The numbering given in parenthesis is in ac-
cordance with the ORTEP representation. C(6)–N(1) is a double
bond. C(5)–O(2) length is greater than C(7)–O(1). Even though
both are carbonyl groups of dimedone moiety, the higher value
of C(5)–O(2) may be due the single bond character of the bond
as O(2) is hydrogen bonded to H(2) of N(2). Further evidence is
provided by the following details of the hydrogen bond. N(2)–
H(2). . . . .O(2); bond angle 136.5◦;bond length–N(2)–H(2) 0.94
A◦; H(2) . . . O(2) 1.00 A◦.
Electronic Spectrum
The electronic spectrum shows all the peaks expected of a
monophenyl hydrazone.[3] A weak band at 286 nm and a strong
absorption band at 386 nm are clear indications of a hydrazone
form. The azo form is excluded as a strong K band,[4] at 270–
280 nm, which is characteristic of an azo form is absent in
the spectrum of the compound under investigation. The band at
510 nm may be due to a chelated ketonic[5] structure.
IR Spectrum
The IR spectrum of the AD shows almost all bands expected
of an azo betadiketone compound. The intense bands in the
carbonyl region 1673 and 1623 cm−1 confirmed the presence[6]
of diketo groups. The shift of these bands to a lower region
compared to those expected for β diketones (∼1700 cm−1
)
may be attributed to the conjugation of the >C O groups with
>C N of the hydrazone form. A band at still lower frequency
may be due to the stretching of another >C O involved in a
hydrogen bonding with >NH. No absorption bands were seen ∼
3600 cm−1 (free-OH) or ∼3500 cm−1 (free-NH). However, the
presence of a broad band at ∼3400 cm−1 indicated hydrogen
Analytical and Spectral Features of the Metal Complexes
of AD
. . .
. . .
bonded OH N or H N O groups. The νC N absorption
Spiro5,5-dimethylcyclohexane1,2,3trione2-phenyhydrazone
occurs at the same region as that of C O. In non-conjugated yielded stable complexes with Fe(III), Co(II), Ni(II), Cu(II) and
systems, νC N absorption normally appears between 1690 and Zn(II). The complexes were amorphous and powdery in nature.

PHENYLAZODIMEDONE AND ITS COMPLEXES
347
FIG. 1. Ortep representation of phenylazodimedone (AD).
The analytical and spectral characterization were conducted to ment of these groups in co-ordination. Trivalent iron has a ten-
assign the geometry of the complexes. The formation of the dency to have charge-transfer bands in the near UV which have
complexes can be represented by the following equation.
many shoulders extending to the visible region that make the
interpretation difficult. The magnetic moment,[9] was typical of
an octahedral geometry viz. 5.91 B.M. Cobalt (II) complex was
brown in color with a pink tinge. This is typical of an octahedral
3LH + M3+ → ML3 + 3H+
2LH + M2+ → ML2 + 2H+
4
4
geometry. The band at 512 may be due to Tlg(F) → A2g of
Co(II) in an octahedral environment. But the magnetic moment
value of 3.82 B.M was found to be too low for an octahedral
geometry. Nickel complex was brown in color and diamagnetic.
Where LH is the ligand AD and L− is its monovalent ion, M3+
=
Fe(III) and M2+= Co(II), Ni(II), Cu(II) or Zn(II).
The physico-chemical and electronic spectral data are given
1
1
The bands at 330nm due to A1g → B1g transition and the
charge transfer band at 292nm also indicated the square-planar
geometry of the complex. Copper complex was olive green in
color as expected and a band,[10] corresponding to the absorption
was observed at 686 nm. The explanation of the spectrum was
rather difficult owing to the enveloping of bands. However, this
in Table 3.
Electronic Spectral and Magnetic Data
The electronic absorption bands of all the complexes bear
close resemblance with those of the AD. This showed that no
structural alteration has occured to AD on complexation. How-
ever, a slight shift in the absorption maxima of > C O and
>C N bands were seen, and may be because of the involve-
2
2
can be assigned to B1g → A1g transition in a square-planar
geometry. The magnetic moment obtained of 2.10 B.M. was
within the range (1.75–2.20 B.M.) expected for magnetically
dilute square-planar copper(II) complexes.
TABLE 1
Single crystal XRD data of AD
IR Spectra
The position of the free carbonyl stretching band of AD
was only marginally (∼30 cm−1) altered in the IR spec-
tra of complexes, showing that it was still free in the com-
plexes. The band corresponding to hydrogen bonded car-
bonyl group has been lowered, that may be assigned to
Empirical formula
F.W.
Temperature
Wave length (Mo Kα)
Crystal system
Space group
C14H16N2O2
244.29
293 K
0.71073 A◦
Monoclinic
P21/c
Unit cell dimensions (A◦)
a = 10.7285: b = 5.845: c = 20.8152
Inter axial angles (deg)
α = 90.000 : β = 96.946 : γ = 90.000
z value = 4
TABLE 2
Bond length between selected atoms
Bond
Bond length (A◦)
1.253 Mg/m3
C(6)–N(1)
N(1)–N(2)
N(2)–H(2)
C(5)–O(2)
C(7)–O(1)
C(9)–N(2)
1.322
1.2987
0.94
1.2340
1.2149
1.406
Density (calc.)
Volume (A3)
1295.28 (8)
10766/2011
0.0526,
wR2= 0
Reflections collected/used
Residuals (all data) R1

348

PHENYLAZODIMEDONE AND ITS COMPLEXES
349
TABLE 4
TABLE 5
Significant 1HNMR spectral assignments of zinc complex of
AD
Significant IR spectral bands of complexes and their
assignments
Sl.
Free ν Chelated
δ(ppm)
Proton assignment
no. Compound C O
νC O νC N νM N νM O
1.2(s,6H)
2.7(s,4H)
7.5(unsymm.)
geminal CH3
>CH2
Aromatic
1.
2.
3.
4.
5.
[FeL3] 1658(s) 1547(m) 1590(m) 554(w) 439(w)
[CoL2] 1660(s) 1546(m) 1595(m) 564(w) 439(w)
[NiL2] 1658(s) 1547(m) 1591(m) 582(w) 447(w)
[CuL2] 1642(s) 1520(m) 1590(m) 519(w) 440(w)
[ZnL2] 1659(s) 1546(m) 1592(m) 553(w) 444(w)
δ = Chemical shift; s = singlet.
1H NMR Spectrum
1H NMR spectrum of the diamagnetic ZnL2 complex has
been recorded and the data are given in Table 5. The promi-
nent feature of the spectrum was the absence of N H peak at
∼15 ppm,[12] which was present in the NMR spectrum of AD.
This was a clear indication of coordination through N to metal
replacing H. Other peaks were the same as those the 1H NMR
spectrum of AD.
L = mono anion of AD(LH); s = strong; m = medium; w = weak.
metal bonded carbonyl group. A new band at ∼440 cm−1 may
be assigned to νM O and the band at ∼560 cm−1 may be
assigned to νM–N,[11] respectively. Other bands of AD such
as those at 3060 cm−1 of aromatic C H, bands at 2959 and
2850 cm−1 of C H stretch and at 1394 cm−1 of geminal
dimethyl C H deformation were retained in the spectra of
the complexes. Important bands and assignments are given in
Table 4.
Mass Spectrum
The ESI mass spectrum of copper(II) complex (Figure 2)
was found to be have very conspicuous M+ (m/z 550)
FIG. 2. ESI Mass spectrum of CuL2.

350
S. SETH AND K. K. ARAVINDAKSHAN
CONCLUSION
In this communication, the synthesis and characterization of
spiro5,5-dimethylcyclohexane1,2,3-trione2-phenylhydrazone
(AD) and its Fe(III), Co(II), Ni(II), Cu(II) and Zn(II) complexes
have been discussed. The structure of AD has been confirmed
with single crystal XRD data and by other physico-chemical
methods. An attempt has been made to suggest the structures
of the complexes with the support of mass spectrum of one of
the complexes, CuL2 and other spectral techniques. The single
crystals of metal complexes were not obtained despite several
attempts. From the available data, it is clear that AD acts as
monovalent, bidentate ligand coordinating through nitrogen
and also the oxygen of the carbonyl group involved in hydrogen
bonding, replacing the H with metal ion. Octahedral/distorted
octahedral geometry has been assigned to Fe(III) and Co(II)
complexes, and square-planar geometry to Ni(II) and Cu(II)
complexes. The four-coordinate Zn(II) complexes may be tetra-
hedral in geometry. The tentative structures of the complexes
are given in Figures 3, 4 and 5.
FIG. 3. Tentative structure of FeL3.
SUPPLEMENTARY MATERIAL
Crystallographic data for structural analysis have been
deposited with the Cambridge Crystallographic Data Cen-
tre, CCDC No.689573. This data can be obtained free of
charge from The Cambridge Crystallographic Data Centre
via www.ccdc.cam.ac.uk/data request/cif or from the Cam-
bridge Crystallographic. Data Centre, 12 union Road, Cam-
bridge CB21EZ,UK;fax (+44) 1223-336-033; or e-mail:
deposit@ccdc.cam.ac.uk.
FIG. 4. Tentative structure of ML2 where M = Ni(II) or Cu(II).
REFERENCES
1. El-Shetary, B.A., Stefan, S.L., Abdel-Moez, M.S., and Mashaly, M.M.
Formation constants of trivalent lanthanide metal ions and hydrazone β-
diketones in 75% dioxane-water solvent. Can. J. Chem., 1988, 66, 2362–
2366.
2. Vogel, A.I., A Textbook of Quantitative Inorganic Analysis, ELBS and
Longman: London,1978.
3. Yao, H.C. Azohydrazone conversion.II The coupling of Diazonium ion with
β-Diketones. J. Org. Chem., 1964, 29, 2959–2963.
4. Yao, H.C., and Resnick, P., Azo-hydrazone conversion.I. The Japp- Klinge-
mann Reaction. J. Am. Chem. Soc., 1962, 84, 3514–3517.
5. Barnes, R.P., and Pinkney, G.E., Absorption spectra of some α and β-
Diketones. J. Am. Chem. Soc., 1953, 75, 479–480.
6. Dyer, R., Application of Absorption Spectroscopy of Organic Compounds,
Prentice Hall, Eaglewood Cliffs, N.J., 1965.
7. Silverstein, R.M., and Webster, F.X., Spectrometric Identification of Or-
ganic Compounds., John Wiley & Sons, Inc. New York, 1998.
8. Budzikiewicz, H., Djerassi, C., and Williams, D.H., Mass Spectrometry of
Organic Compounds., Holden-Day, San Francisco, 1967.
9. Cotton, F.A., and Wilkinson, G., Advanced Inorganic Chemistry, John
Wiley, New York, 1980.
FIG. 5. Tentative structure of ZnL2.
10. Sutton, D., Electronic Spectra of Transition Metal Complexe, McGraw Hill,
London, 1968.
11. Nakamato, K., Infrared and Raman Spectra of Inorganic and Coordination
Compounds., Wiley, New York, 1986.
12. Drago, R.S., Physical Methods for Chemists, Second edition, Saunders
Colleges Publishing, New York, 1977.
peak, which confirmed its stoichiometry, ML2. The base peak
(m/z 245) is that of AD. The (M+2) peak must be due
to the isotope of copper, 65Cu with an abundance of 30.9
percent.