New complexes of 2-hydroxy-1-naphthoic acid and X-ray crystal structure of [Pt(hna)(PPh3)2]

Article abstract of DOI:10.1016/j.molstruc.2012.09.018

The solid complexes [Zn(Hhna)₂(H₂O)₂], (PPh₄)₂[MoO₂(hna)₂], [Pd(Hhna) ₂], [Pt(PPh₃)₂(hna)], [Pd(bpy)(hna)], [Pd(phen)(hna)], [Ag(Hhna)(H₂O)₂] and [Ag(Hhna)(PPh ₃)(H₂O)] (H₂hna = 2-hydroxy-1-naphthoic acid) were prepared and characterized by IR, UV-vis, ¹H NMR, ¹³C NMR, ³¹P NMR and mass spectrometry, and by elemental analysis and thermal measurements. 2-Hydroxy-1-naphthoic acid coordinates the metal ions in either binegative or mononegative bidentate manner through the deprotonated hydroxy and the deprotonated carboxylate oxygen or the carboxylato oxygen atoms. The crystal structure of [Pt(hna)(PPh₃)₂] has been determined, the Pt(II) center displays a square-planar geometry through the binegative bidentate 2-hydroxy-1-naphthoic acid dianion.

Full text of DOI:10.1016/j.molstruc.2012.09.018

Journal of Molecular Structure 1036 (2013) 196–202
Contents lists available at SciVerse ScienceDirect
Journal of Molecular Structure
journal homepage: www.elsevier.com/locate/molstruc
New complexes of 2-hydroxy-1-naphthoic acid and X-ray crystal structure
of [Pt(hna)(PPh3)2]
Shadia A. Elsayed a, Ahmed M. El-Hendawy a, Ian S. Butler b, Sahar I. Mostafa c,
⇑
a Chemistry Department, Faculty of Science, Mansoura University, Damietta, Egypt
b Chemistry Department, McGill University, Montreal, QC, Canada H3A 2K6
c Chemistry Department, Faculty of Science, Mansoura University, Mansoura 35516, Egypt
h i g h l i g h t s
"
"
"
"
New complexes of 2-hydroxy-1-naphthoic (H2hna) are reported.
The X-ray structure of [Pt(hna)(PPh3)2] was determined.
In Pd(II), Pt(II) and MO2 complexes, H2hna coordinates via COO– and hydroxo atoms.
2þ
H2hna coordinates Zn(II), Ag(II) and Pd(II) through –COO- oxygen centers.
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 17 June 2012
Received in revised form 1 September 2012
Accepted 4 September 2012
Available online 19 September 2012
The solid complexes [Zn(Hhna)2(H2O)2], (PPh4)2[MoO2(hna)2], [Pd(Hhna)2], [Pt(PPh3)2(hna)], [Pd(bpy)(hna)],
[Pd(phen)(hna)], [Ag(Hhna)(H2O)2] and [Ag(Hhna)(PPh3)(H2O)] (H2hna = 2-hydroxy-1-naphthoic acid)
were prepared and characterized by IR, UV–vis, 1H NMR, 13C NMR, 31P NMR and mass spectrometry, and
by elemental analysis and thermal measurements. 2-Hydroxy-1-naphthoic acid coordinates the metal ions
in either binegative or mononegative bidentate manner through the deprotonated hydroxy and the depro-
tonated carboxylate oxygen or the carboxylato oxygen atoms. The crystal structure of [Pt(hna)(PPh3)2] has
been determined, the Pt(II) center displays a square-planar geometry through the binegative bidentate
2-hydroxy-1-naphthoic acid dianion.
Keywords:
2-Hydroxy-1-naphthoic acid
IR
NMR
Ó 2012 Elsevier B.V. All rights reserved.
Palladium
Silver
1. Introduction
The formation constant of Cr(III), Sc(III) and Y(III) complexes of
2-hydroxy-1-naphthoic acid have been determined on the basis of
2-Hydroxy-1-naphthoic acid is a naphthalene compound
with a weak fluorescence that is mainly used as an intermediate
in the production of dyes and photosensitive materials [1].
spectrophotometric and potentiometric techniques [6]. Some tran-
sition-metal complexes of salicylic and
have also been reported [7–9].
a-hydroxynaphthoic acids
a
-Hydroxynaphthoic acids are the main constituent of several
In this paper, we explore the synthesis of new complexes of
2-hydroxy-1-naphthoic acid (H2hna) with Zn(II), Mo(VI), Ag(I),
Pd(II) and Pt(II) ions. The composition of the complexes was deter-
mined on the basis of various physical and chemical measure-
ments. The X-ray crystal structure of [Pt(hna)(PPh3)2] have been
also determined.
metabolites of polynuclear aromatic hydrocarbons, which are rec-
ognized as serious pollutants of the environment [2]. In addition,
a
-hydroxynaphthoic acid (H2hna) can adopt several different
modes of bonding. It can function as a bidentate ligand through
its deprotonated -hydroxy and carboxylate oxygen atoms to form
a
stable 6-membered chelate rings with metal ions [3]. In the com-
plexes, [Zn(Hhna)2] and [Ln(Hhna)3] (Ln(III) = La–Lu), the monoan-
ion Hhnaꢀ coordinates to the metal ion through the two oxygen
atoms of the deprotonated hydroxy and carboxylate group [4,5].
2. Experimental
2.1. Materials
All reagents were purchased from Alfa/Aesar and Aldrich Chem-
ical Co. and all manipulations were performed under aerobic con-
ditions using materials and solvents as received. [Pd(bpy)Cl2],
⇑
Corresponding author. Tel.: +20 100 8502625; fax: +20 50 2246781.
E-mail address: sihmostafa@yahoo.com (S.I. Mostafa).
0022-2860/$ - see front matter Ó 2012 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.molstruc.2012.09.018

S.A. Elsayed et al. / Journal of Molecular Structure 1036 (2013) 196–202
197
[Pd(phen)Cl2] and [Pt(PPh3)2Cl2] were prepared by the literature
methods [10,11].
2.3.3. [Ag(Hhna)(H2O)2]ꢂ2H2O
Silver nitrate (0.17 g, 1 mmol) in water (2 cm3) was added to 2-
hydroxy-1-naphthoic acid (0.19 g, 1 mmol) in aqueous NaOH
(0.04 g, 1 mmol; 25 cm3). The reaction mixture was stirred in the
dark for 4 h. The white complex was filtered off, washed with
water and dried in vacuo.
2.2. Instrumentation
Elemental analyses and X-ray crystallography were performed
in the Department of Chemistry, Montreal University. The crystal
structure were measured at The X-ray Crystal Structure Unit, using
a Bruker Platform diffractometer, equipped with a Bruker MART 4K
Charger-Coupled Device (CCD) Area Detector using the program
APEX II and a Nonius Fr591 rotating anode (Copper radiation)
equipped with Montel 200 optics. The crystal-to-detector distance
was 5 cm and the data collection was carried out in 512 ꢁ 512 pix-
el mode. The initial unit cell parameters were determined by the
least-squares fit of the angular setting of strong reflections, col-
lected by a 10.0° scan in 33 frames over three different parts of
the reciprocal space (99 frames total) and one complete sphere
of data was collected. NMR spectra were recorded on VNMRS
500-MHz spectrometer in DMSO-d6 using TMS as reference. Mass
spectra, ESI-MS and EI-MS were recorded using LCQ Duo and dou-
ble-focusing MS25RFA instruments, respectively. Electronic spec-
Yield: 0.25 g, 77%. Anal. Calc. for AgC11H15O7: C, 36.0; H, 4.1%,
Found: C, 36.5; H, 3.8%. Conductivity data (10ꢀ3 M in DMF):
KM = 9.0
1251;
(Ag–O), 500. 1H NMR (ppm): 6.96 (H(3), d, J = 9 Hz, 1H);
X mas(OCO), 1579; ms(OCO), 1430; m(CO),
ꢀ1. IR (cmꢀ1):
m
7.15 (H(4), d, J = 8 Hz, 1H); 9.55 (H(5), d, J = 9 Hz, 1H); 7.35 (H(6),
t, J = 8 Hz, 1H); 7.71 (H(7), t, J = 9 Hz, 1H); 7.65 (H(8), dd, 8 Hz,
1H), 10.31 (H(OH), s). 13C NMR (ppm): C(1), 134.61; C(2), 161.08;
C(3), 133.02; C(4), 128.42; C(5), 121.68; C(6), 109.13; C(7),
120.79; C(8), 126.13; C(9), 126.82; C(10), 127.63; C(11), 173.61.
MS (m/z): 698.4 (Calcd. 698.0).
2.3.4. [Ag(Hhna)(PPh3)(H2O)]
Silver nitrate (0.09 g, 0.5 mmol) in water (1 cm3) was added to
triphenylphosphine (0.262 g, 1 mmol) in acetonitrile (10 cm3).
The reaction mixture was heated gently with stirring for 2 h in
the dark and 2-hydroxy-1-naphthoic acid (0.1 g, 0.5 mmol) in
methanol containing KOH (0.028 g, 0.5 mmol; 15 cm3) was added.
The reaction mixture was stirred and warmed for further 5 h in the
dark. The white precipitate was filtered off, washed with methanol
and dried in vacuo.
tra were recorded in DMF using
a Hewlett–Packard 8453
spectrophotometer. Thermal analysis measurements were made
in the 20–800 °C range at the heating rate of 20 °C minꢀ1 using
Ni and NiCo as references, on a on a TA instrument TGA model
Q500Analyzer TGA-50. Molar conductivity measurements were
carried out at room temperature on a YSI Model 32 conductivity
bridge.
Yield: 0.19 g, 66%. Anal. Calc. for AgC29H24O4P: C, 60.4; H, 4.4%,
Found: C, 60.2; H, 4.2%. Conductivity data (10ꢀ3 M in DMF):
KM = 9.0 (OH), 3478;
X
ꢀ1. IR (cmꢀ1):
m
mas(OCO), 1617; ms(OCO),
2.3. Preparation of the complexes
1433; (COH), 1285; m
m
(M–O), 512. 1H NMR (ppm): 6.91 (H(3), d,
J = 9 Hz, 1H); 7.30 (H(4), d, J = 8 Hz, 1H); 9.55 (H(5), d, J = 8 Hz,
1H); 7.49 (H(6), t, J = 8 Hz, 1H); 7.11 (H(7), t, J = 8 Hz, 1H); 7.63
(H(8), d, J = 9 Hz, 1H), 10.20 (H(OH), s). 31P NMR: (200 MHz,
ppm) 9.71. MS (m/z): 575.0 (Calcd. 575.0), 369.4 (Calcd. 370.0).
2.3.1. [Zn(Hhna)2(H2O)2]ꢂH2O
Zinc sulfate (0.15 g, 0.5 mmol) in water (5 cm3) was added to 2-
hydroxy-1-naphthoic acid (0.19 g, 1 mmol) in aqueous NaOH
(0.08 g, 2 mmol; 10 cm3). The off-white precipitate was heated
gently with stirring for 3 h. It was filtered off, washed with water
and dried in vacuo.
2.3.5. [Pd(bpy)(hna)]ꢂH2O
Solid [Pd(bpy)Cl2] (0.085 g, 0.25 mmol) was added to 2-hydro-
xy-1-naphthoic acid (0.05 g, 0.25 mmol) in methanol containing
KOH (0.028 g, 0.5 mmol; 15 cm3). The reaction mixture was stirred
for 48 h and the yellow precipitate was filtered off, washed with
methanol and air-dried.
Yield: 0.183 g, 77%. Anal. Calc. for C22H20O9Zn: C, 53.5; H, 4.1%,
Found: C, 53.5; H, 4.0%. Conductivity data (10ꢀ3 M in DMF):
KM = 6.0
X
ꢀ1, IR (cmꢀ1):
m
(OH), 3460;
mas(OCO), 1545; ms(OCO),
1392; (CO), 1250;
m
m
(Zn-O), 503. 1H NMR (ppm): 7.02 (H(3), d,
J = 9 Hz, 1H); 7.80 (H(4), d, J = 9 Hz, 1H); 9.43 (H(5), d, J = 8 Hz,
1H); 7.21 (H(6), t, J = 8 Hz, 1H); 7.41 (H(7), t, J = 8 Hz, 1H); 7.71
(H(8), d, J = 8 Hz, 1H); 10.16 (H(OH), s). 13C NMR (ppm): C(1),
134.81; C(2), 160.41; C(3), 134.62; C(4), 131.86; C(5), 123.62;
C(6), 117.01; C(7), 118.14; C(8), 125.2; C(9), 128.50; C(10),
128.71; C(11), 174.79. MS (m/z): 475.8, (Calcd. 475.5), 439.0 (Calcd.
439.5) and 395.2 (Calcd. 395.5).
Yield: 0.077 g, 65%. Anal. Calc. for C21H16N2O4Pd: C, 54.0; H, 3.5;
N, 6.0%, Found that C, 53.6; H, 4.1; N, 6.2. Conductivity data
(10ꢀ3 M in DMF): KM = 6.0
X
ꢀ1. IR (cmꢀ1):
(Pd–O), 505;
m
as(OCO), 1615; ms
(OCO), 1384;
m
(CO), 1261;
m
m
(Pd–N), 476. 1H NMR:
6.93 (H(3), d, J = 9 Hz, 1H); 8.46 (H(5), d, J = 8 Hz, 1H); 7.22 (H(6),
t, J = 8 Hz, 1H). 13C NMR: C(1), 135.29; C(2), 167.33; C(3), 131.78;
C(4), 130.26; C(5), 123.78; C(6), 115.23; C(7), 121.60; C(8),
124.31; C(9), 127.97; C(10), 127.85; C(11), 173.25. MS (m/z):
448.6 (Calcd. 448.4).
2.3.2. [Pd(Hhna)2]ꢂH2O
K2PdCl4 (0.16 g, 0.5 mmol) in water (5 cm3) was added to an
aqueous solution 2-hydroxy-1-naphthoic acid (0.19 g, 1 mmol;
10 cm3) containing NaOH (0.04 g, 1 mmol). The reaction mixture
was heated with stirring for 6 h, upon which a brown precipitate
was observed. It was filtered off, washed with water and air-dried.
Yield: 0.146 g, 62%. Anal. Calc. for C22H16O7Pd: C, 53.0; H, 3.2%,
2.3.6. [Pd(phen)(hna)]
The synthesis of [Pd(phen)(hna)] was achieved by a similar pro-
cedure to that for [Pd(bpy)(hna)] with [Pd(phen)Cl2] replacing
[Pd(bpy)Cl2].
Yield: 0.067 g, 67%. Anal. Calc. for C24H18N2O4Pd: C, 58.0; H, 3.7;
Found: 53.3; H, 2.9%. Conductivity data (10ꢀ3
KM = 7.0 (OH), 3470; as(OCO), 1574;
ꢀ1. IR (cmꢀ1):
1431; (CO), 1249;
(Pd–O), 539. 1H NMR (ppm): 6.90 (H(3), d,
M
in DMF):
s(OCO),
N, 5.6%, Found C, 57.8; H, 3.2; N, 5.4%. Conductivity data (10ꢀ3 M in
X
m
m
m
DMF): KM = 9.0 as(OCO), 1613;
X
ꢀ1. IR (cmꢀ1):
m
ms(OCO), 1386;
m
m
m
(CO), 1260; (Pd–O), 503; m
m
(Pd-N), 481. 1H NMR: 6.86 (H(3), d,
J = 9 Hz, 1H); 7.80 (H(4), d, J = 9 Hz, 1H); 8.47 (H(5), d, J = 8.5 Hz,
1H); 7.33 (H(6), t, J = 8.5 Hz, 1H); 7.83 (H(7), t, J = 9 Hz, 1H); 7.65
(H(8), dd, J = 8.5 Hz, 1H), 10.19 (H(OH), s). 13C NMR (ppm): C(1),
136.91; C(2), 160.55; C(3), 133.81; C(4), 127.14; C(5), 122.67;
C(6), 109.56; C(7), 119.34; C(8), 125.99; C(9), 128.09; C(10),
126.72; C(11), 175.00. ESI-MS (m/z): 479.0 (Calcd. 480.4), 437.0
(Calcd. 436.4) and 404.0 (Calcd. 404.4).
J = 9 Hz, 1H); 8.42 (H(5), d, J = 8 Hz, 1H); 7.20(H(6), t, J = 8 Hz,
1H). MS (m/z): 473.0 (Calcd. 472.4).
2.3.7. [Pt(PPh3)2(hna)]
[Pt(PPh3)2Cl2] (0.16 g, 0.2 mmol) in ethanol (10 cm3) was added
to 2-hydroxy-1-naphthoic acid (0.04 g, 0.2 mmol) in ethanol con-
taining KOH (0.016 g, 0.3 mmol; 15 cm3). The reaction mixture

198
S.A. Elsayed et al. / Journal of Molecular Structure 1036 (2013) 196–202
Table 1
was heated with stirring over night at 60 °C. Slow evaporation of
the resulting yellow solution produced fine yellow crystals.
Yield: 0.13 g, 71%. Anal. Calc. for C47H36O3P2Pt: C, 62.3; H, 4.0%,
Found: C, 62.4; H, 3.9. Conductivity data (10ꢀ3 M in DMF):
Crystal data and structure refinement for [Pt(hna)(PPh3)2].
Empirical formula
C47H36O3P2Pt
Formula weight
Temperature
Wavelength
Crystal system
Space group
Unit cell dimensions
905.79
150 K
0.71073 Å
Orthorhombic
Aba2
a = 18.8744(9) Å, a = 90 °C
b = 23.3006(11) Å, b = 90 °C
KM = 8.0
X mas(OCO), 1615; ms(OCO), 1375; m(CO),
ꢀ1. IR (cmꢀ1):
1259;
m
(Pt–O), 500. 1H NMR: 6.89 (H(3), d, J = 9 Hz, 1H); 8.42
(H(5), d, J = 9 Hz, 1H); 7.17 (H(6), t, J = 8 Hz, 1H); 7.43 (H(7), t,
8 Hz, 1H). 31P NMR: (200 MHz, ppm), 8.22, 11.80. MS (m/z):
905.3 (Calcd. 905.0).
c = 18.3335(9) Å,
8062.8(7) Å3
8
c = 90 °C
Volume
Z
Density (calculated)
Absorption coefficient
F(000)
Crystal size
Theta range for data collection
Index ranges
Reflections collected
Independent reflections
Absorption correction
Max. and min. transmission
Refinement method
Data/restraints/parameters
Goodness-of-fit on F2
Final R indices [I > 2sigma(I)]
R indices (all data)
Absolute structure parameter
Largest diff. peak and hole
2.3.8. (PPh4)2[MoO2(hna)2]
[MoO2(acac)2] (0.13 g, 0.4 mmol) in methanol (2 cm3) was
added 2-hydroxy-1-naphthoic acid (0.15 g, 0.8 mmol) in methanol
(5 cm3). The reaction mixture was heated under reflux for 3 h and
tetraphenylphosphonium chloride (0.3 g, 0.8 mmol) in water
(5 cm3) was added.
1.492 g/cm3
3.600 mmꢀ1
3600
0.20 ꢁ 0.16 ꢁ 0.04 mm
1.75–27.49 °C
ꢀ24 6 h 6 24, ꢀ30 6 k 6 30, ꢀ23 6 l 6 23
138010
9254 [Rint = 0.056]
Semi-empirical from equivalents
0.8659 and 0.6602
Full-matrix least-squares on F2
9254/1/478
The pale yellow precipitate was filtered off, washed with water
and methanol, and finally air-dried.
Yield: 0.37 6 g, 80%. Anal. Calc. for C70H52MoO8P2: C, 71.3; H,
4.4%, Found: C, 70.9; H, 3.8%. Conductivity data (10ꢀ3 M in DMF):
KM = 76.0
X mas(OCO), 1618; ms(OCO), 1387; m(CO),
ꢀ1. IR (cmꢀ1):
1261. 1H NMR (ppm): 6.88 (H(3), d, J = 9 Hz, 1H); 8.47 (H(5), d,
J = 9 Hz, 1H); 7.25 (H(6), t, J = 8 Hz, 1H); 7.48 (H(7), t, J = 8 Hz,
1H). 13C NMR (ppm): C(1), 135.81; C(2), 163.11; C(3), 132.62;
C(4), 130.86; C(5), 123.55; C(6), 116.91; C(7), 118.50; C(8),
124.61; C(9), 128.46; C(10), 128.11; C(11), 173.79. MS (m/z):
500.0 (Calcd. 500.0).
1.052
R1 = 0.0234, wR2 = 0.0429
R1 = 0.0301, wR2 = 0.0438
0.005(4)
1.208 and ꢀ0.813 e/Å3
3. Results and discussion
Section 2 describes the synthesis of some new complexes of 2-
hydroxy-1-naphthoic acid (H2hna; Fig. 1). The elemental analyses
for the complexes are in agreement with the assigned formulae.
The molar conductivities (KM) in DMF at room temperature sug-
gest the non-electrolytic nature of the complexes [12].
3.1. X-ray crystal structure of [Pt(hna)(PPh3)2]
Orange crystals of [Pt(hna)(PPh3)2], suitable for X-ray analysis,
crystallized in an orthorhombic lattice with space group symmetry
Aba2. The crystal data and structure refinement details for this
complex are given in Table 1.
The structure of the complex with the atomic labeling is shown
in Fig. 2. Selected bond angles (°) and bond lengths (Å) are listed in
Table 2. The platinum(II) ion is four coordinated in a square-planar
geometry by 2-hydroxy-1-naphthoic acid and two triphenylphos-
phine ligands. The 2-hydroxy-1-naphthoic acid anion (hna2ꢀ
)
coordinates Pt(II) in the expected bidentate fashion via the depro-
tonated hydroxy oxygen O(1) and the deprotonated carboxylate
oxygen O(2), forming a 6-membered chelate ring with O(1)–Pt–
O(2), P(1)–Pt–P(2), O(1)–Pt–P(1) and O(2)–Pt–P(2) bite angles of
Fig. 2. X-ray crystal structure of [Pt(hna)(PPh3)2].
86.61(11)°, 99.52(4)°, 87.98(8)° and 85.76(9)°, respectively. The
two PPh3 are cis to each other. The structure of [Pt(PPh3)2(hna)]
HO
O
adopts
a nearly ideal square-planar geometry with trans
11
C
H
O
O(2)–Pt–P(1) and O(1)–Pt–P(2) bond angles of 171.48(7)° and
172.34(7)°, respectively. The other angles around the Pt(II) center
deviate slightly from the ideal value (90°), ranging from 85.76(9)
to 99.52(4). The bond distances, Pt–O(1), 2.017(2) Å; Pt–O(2),
2.026(2) Å; Pt–P(1), 2.2417(9) Å and Pt–P(2), 2.2635(10) Å are in
the usual range. The strong coordination of Pt(II) to the two oxygen
centers, Pt–O(1) and Pt–O(2), compared to that of the triphenyl-
phosphine phosphorous atoms, Pt–P(1) and Pt–P(2) is due to the
high basicity of O(1) and O(2) compared to P(1) and P(2) as well
as the atomic size of oxygen and phosphorus atoms [13]. Also,
the bond length for Pt–O(1), 2.017(2) Å is shorter than that for
8
1
9
2
7
6
3
10
5
4
Fig. 1. 2-Hydroxy-1-naphthoic acid (H2hna).

S.A. Elsayed et al. / Journal of Molecular Structure 1036 (2013) 196–202
199
Table 2
twists between the phenyl group of the PPh3 and the naphthoic
rings.
Bond lengths (Å) and angles (°) for C47H36O3P2Pt.
Bond length (Å)
Bond angles (°)
3.2. Vibration spectra
Pt(1)–O(1) 2.017(2)
Pt(1)–O(2) 2.026(2)
Pt(1)–P(1) 2.2417(9)
Pt(1)–P(2) 2.2635(10)
P(1)–C(31) 1.809(4)
P(1)–C(41) 1.818(4)
P(1)–C(21) 1.830(4)
P(2)–C(61) 1.813(5)
P(2)–C(71) 1.813(4)
P(2)–C(51) 1.826(4)
O(1)–C(1) 1.331(4)
O(2)–C(11) 1.302(5)
O(11)–C(11) 1.238(4)
C(1)–C(10) 1.390(5)
C(1)–C(2) 1.427(5)
C(2)–C(3) 1.357(5)
C(3)–C(4) 1.414(5)
C(4)–C(5) 1.404(5)
C(4)–C(9) 1.427(5)
C(5)–C(6) 1.352(5)
C(6)–C(7) 1.405(6)
C(7)–C(8) 1.365(5)
C(8)–C(9) 1.409(5)
C(9)–C(10) 1.455(5)
C(10)–C(11) 1.483(5)
C(21)–C(26) 1.377(5)
C(21)–C(22) 1.400(5)
C(22)–C(23) 1.384(5)
C(23)–C(24) 1.378(6)
C(24)–C(25) 1.362(6)
C(25)–C(26) 1.388(5)
C(31)–C(32) 1.391(5)
C(31)–C(36) 1.402(5)
C(32)–C(33) 1.395(5)
C(33)–C(34) 1.372(6)
C(34)–C(35) 1.374(5)
C(35)–C(36) 1.385(5)
C(41)–C(42) 1.370(5)
C(41)–C(46) 1.402(5)
C(42)–C(43) 1.396(6)
C(43)–C(44) 1.390(6)
C(44)–C(45) 1.355(6)
C(45)–C(46) 1.412(6)
C(51)–C(56) 1.376(5)
C(51)–C(52) 1.403(5)
C(52)–C(53) 1.400(6)
C(53)–C(54) 1.388(6)
C(54)–C(55) 1.384(6)
C(55)–C(56) 1.390(5)
C(61)–C(66) 1.386(6)
C(61)–C(62) 1.395(6)
C(62)–C(63) 1.380(6)
C(63)–C(64) 1.388(8)
C(64)–C(65) 1.369(7)
C(71)–C(76) 1.385(5)
C(71)–C(72) 1.400(5)
C(72)–C(73) 1.376(6)
C(73)–C(74) 1.378(6)
C(74)–C(75) 1.394(7)
C(75)–C(76) 1.380(6)
O(1)–C(1)–C(10) 126.2(3)
O(1)–C(1)–C(2) 114.3(3)
C(10)–C(1)–C(2) 119.4(3)
C(3)–C(2)–C(1) 121.7(4)
C(2)–C(3)–C(4) 121.0(4)
C(5)–C(4)–C(3) 121.3(4)
C(5)–C(4)–C(9) 119.6(4)
C(3)–C(4)–C(9) 119.0(3)
C(6)–C(5)–C(4) 121.6(4)
C(5)–C(6)–C(7) 119.2(4)
The IR spectral data of 2-hydroxy-1-naphthoic acid and its com-
plexes are reported in Section 2. The IR spectrum of the free H2hna
(Fig. 1) exhibits a broad absorption band at 2900 cmꢀ1 which is
assigned to the intra-molecular hydrogen bond
m
(O–Hꢂ ꢂ ꢂO) vibra-
tion; which is not observed in the spectra of the complexes,
(PPh4)2[MoO2(hna)2], [Pt(PPh3)2(hna)], [Pd(bpy)(hna)] and [Pd
(phen)(hna)], indicating the involvement of the deprotonated hy-
droxy oxygen atom in complexation [15]. This suggestion is further
supported by a slight shift of the band near 1250 cmꢀ1 in the free
C(8)–C(7)–C(6) 120.9(4)
C(7)–C(8)–C(9) 121.3(4)
C(8)–C(9)–C(4) 117.2(3)
C(8)–C(9)–C(10) 123.7(3)
C(4)–C(9)–C(10) 119.2(3)
C(1)–C(10)–C(9) 119.2(3)
C(1)–C(10)–C(11) 120.8(3)
C(9)–C(10)–C(11) 119.5(3)
O(11)–C(11)–O(2) 119.2(3)
O(11)–C(11)–C(10) 120.6(3)
O(2)–C(11)–C(10) 120.2(3)
C(26)–C(21)–C(22) 118.7(4)
C(26)–C(21)–P(1) 124.5(3)
C(22)–C(21)–P(1) 116.7(3)
C(23)–C(22)–C(21) 120.0(4)
C(24)–C(23)–C(22) 120.4(4)
C(25)–C(24)–C(23) 119.7(4)
C(24)–C(25)–C(26) 120.7(4)
C(21)–C(26)–C(25) 120.4(4)
C(32)–C(31)–C(36) 119.0(4)
C(32)–C(31)–P(1) 120.1(3)
C(36)–C(31)–P(1) 120.9(3)
C(31)–C(32)–C(33) 120.3(4)
C(34)–C(33)–C(32) 119.2(4)
C(33)–C(34)–C(35) 121.7(4)
C(34)–C(35)–C(36) 119.4(4)
C(35)–C(36)–C(31) 120.2(4)
C(42)–C(41)–C(46) 120.4(4)
C(42)–C(41)–P(1) 120.2(3)
C(46)–C(41)–P(1) 119.1(4)
C(41)–C(42)–C(43) 120.9(4)
C(44)–C(43)–C(42) 119.4(4)
C(45)–C(44)–C(43) 119.8(4)
C(44)–C(45)–C(46) 122.0(5)
C(41)–C(46)–C(45) 117.5(6)
C(56)–C(51)–C(52) 119.4(4)
C(56)–C(51)–P(2) 121.2(3)
C(52)–C(51)–P(2) 119.1(3)
C(53)–C(52)–C(51) 120.1(4)
C(54)–C(53)–C(52) 119.5(4)
C(55)–C(54)–C(53) 120.0(4)
C(54)–C(55)–C(56) 120.4(4)
C(51)–C(56)–C(55) 120.4(4)
C(66)–C(61)–C(62) 118.6(5)
C(62)–C(61)–P(2) 122.1(4)
C(63)–C(62)–C(61) 120.4(5)
C(62)–C(63)–C(64) 119.7(4)
C(65)–C(64)–C(63) 120.7(4)
C(64)–C(65)–C(66) 119.5(5)
C(61)–C(66)–C(65) 121.1(5)
C(76)–C(71)–C(72) 118.6(4)
C(76)–C(71)–P(2) 124.5(3)
C(72)–C(71)–P(2) 116.8(3)
C(73)–C(72)–C(71) 120.6(4)
C(72)–C(73)–C(74) 120.3(4)
C(73)–C(74)–C(75) 119.7(4)
C(76)–C(75)–C(74) 119.9(4)
C(75)–C(76)–C(71) 120.9(4)
ligand associated with the m(C–O) vibration, which is sensitive to
metal coordination [16]. In the free H2hna, the bending mode of
the hydroxyl –COOH group appears at 1318 cmꢀ1. A shift towards
lower wavenumber is observed because of the participation of the
OH group in inter-hydrogen bonding [9]. Furthermore, the absorp-
tion band at 1459 cmꢀ1 in the free ligand is assigned to d(OH) and
this is shifted to lower wavenumbers upon complex formation [5].
The IR bands at 1634 and 1362 cmꢀ1 in the free ligand may arise
from mas(COO) and ms(COO) of the carboxylic group, respectively.
These modes are affected by coordination and are shifted to lower
wavenumbers, since the carboxylate oxygen center is involved
in coordination [15]. The separation between these two bands
{
m
as(COO) and
m
s(COO), ꢃ200 cmꢀ1} indicates monodentate coordi-
nation of the carboxylate group [17]. The m(OH) mode of the car-
boxylic group in the free H2hna is absent in the spectra of these
complexes, indicating the deprotonation and coordination through
the hydroxy oxygen atom. The absence of any bands around
1700 cmꢀ1 suggests that the carboxylate carbonyl oxygen group
is not involved in coordination [18]. The vibration spectral data
suggest O,O binegative bidentate coordination of hna2ꢀ. On the
other hand, in the IR spectra of the complexes, [Zn(Hhna)2(H2O)2],
[Pd(Hhna)2], [Ag(Hhna)(H2O)]2 and [Ag(PPh3)2(Hhna)], the hydro-
xy group does not participate in coordination to Zn(II), Pd(II) or
Ag(I), suggesting mononegative coordination of Hhnaꢀ through –
COOꢀ [18]. This conclusion is supported by the observation of IR
bands near 1590 and 1430 cmꢀ1 attributed to
mas(COO) and
m
s(COO), respectively. The separation between these bands
{m
as(COO) and
m
s(COO), ꢃ155 cmꢀ1} indicates bidentate coordina-
tion of the carboxylate group [19].
In the complexes, [Pt(PPh3)2(hna)] and [Ag(PPh3)2(Hhna)], the
presence of the PPh3 groups is attested to by the appearance of
strong IR bands near 1100 cmꢀ1, which may be due to
m(P–Cph)
vibrations [20]. The IR spectra of the complexes, [Pd(bpy)(hna)]
and [Pd(phen)(hna)], show bands near 1580, 1515, 1495,
1420 cmꢀ1 that can be attributed to stretching vibrations of the
bpy and phen groups; these bands are at higher wavenumbers
compared with the free bpy and phen indicating their participation
in complexation. Also, the bands near 840, 750 and 725 cmꢀ1 are
assigned to m(CH) vibrations of the coordinated PPh3, bpy and phen
[21]. The IR spectrum of (PPh4)2[MoO2(hna)2] shows bands charc-
terisctic of the cis-MoO2 core (Fig. 3), the bands at 913 and
933 cmꢀ1 are attributed to the
respectively [22,23].
mas(MoO2) and ms(MoO2) modes,
The IR spectra of the complexes show several weak bands in the
540–200 cmꢀ1 region that can be assigned to
(M–N), (M–O),
(M–P) stretches [19,23].
m
m
m
3.3. NMR spectra
Pt–O(2), 2.026(2) Å. The same feature was observed in the X-ray
crystal structures of [Cp2TiL] (H2L = 1-hydroxy-2-naphthoic acid,
2-hydroxy-3-naphthoic acid) [14]. Disregarding the PPh3 ligands,
the [Pt(PPh3)2(hna)] framework is planar and there are significant
The NMR data for free H2hna and some of its complexes in d6-
DMSO are in good agreement with the literature results [24,25]. In
1H NMR spectrum of the free ligand, H3, H4, H5 and H8 signals

200
S.A. Elsayed et al. / Journal of Molecular Structure 1036 (2013) 196–202
probably owing to the decrease in the electronic density on the
aromatic rings upon coordination [21,26].
O
O
O
O
O
O
O
Mo
For the complex, [Pd(Hhna)2], cis and trans isomers are possible
(Fig. 4). Its 1H NMR spectrum reveals the presence of two non-
equivalent resonances for each proton, suggesting the presence
of a mixture of cis/trans (1:4) configurations (Fig. 5) [27]. In the
1H NMR spectra of the complexes, [Pd(bpy)(hna)] and [Pd(phen)(h-
na)], the bpy and phen protons show upfield shifts compared to
those for [PdLCl2] (L = bpy, phen) [26].
C
C
O
In the 13C NMR spectrum of free H2hna, there are eleven reso-
nances at d 108.7, 119.3, 123.8, 124.9, 128.3, 128.4, 129.2, 131.9,
135.1, 160.4 and 172.7 ppm, corresponding to C(6), C(7), C(5),
C(8), C(10), C(9), C(4), C(3), C(1), C(2) and C(11), respectively. Upon
complex formation, downfield shifts for the C(1), C(2)(C-OH), and
C11(COOꢀ) resonances were observed, confirming the participa-
tion of both the carboxylate and hydroxy oxygen centers in coordi-
nation [13]. In the 13C NMR spectra of the complexes, [Pd(Hhna)2]
and [Ag(Hhna)(H2O)2] down field shift in the resonance of
C11(COOꢀ) was observed with little shift of C(1) and C(2), indicat-
ing the participation of the carboxylato oxygen atoms only in coor-
dination [13].
Fig. 3. Structure of [MoO2 (hna)2]2ꢀ
.
appear as doublets at d 7.17, 7.96, 8.45 and 7.83 ppm, respectively
while the H6 and H7 signals are triplets at d 7.34 and 7.53 ppm,
respectively (see Fig.1 for atom numbering scheme). The protons
of the carboxylic and hydroxy groups are seen as a sharp singlet
at d 7.40 ppm and a broad singlet at d 12.45 ppm due to hydrogen
bonding, respectively. In the complexes, (PPh4)2[MoO2(hna)2],
[Pt(PPh3)2(hna)], [Pd(bpy)(hna)] and [Pd(phen)(hna)], the hydroxy
and carboxylic proton signals are missing, indicating the
replacement of the hydroxy and carboxylic protons by the metal
ions [26]. In the spectra of the complexes, [Zn(Hhna)2(H2O)2],
[Pd(Hhna)2], [Ag(Hhna)(H2O)]2 and [Ag(PPh3)2(Hhna)], the carbox-
ylic proton is not observed while the hydroxy proton is observed as
a sharp, upfield shifted signal. This feature supports the coordina-
tion through the carboxylate oxygen centers without any role for
the 2-OH group. The resonances arising from the H3 and H8 protons
are shifted to higher fields to a greater extent than are the others,
The 31P NMR spectrum of [Pt(PPh3)2(hna)] exhibits two signals
at 8.22 and 11.80 ppm indicating the presence of the two coordi-
nated PPh3 groups in a cis-configuration [28]. On the other hand,
the spectrum of [Ag(Hhna)(PPh3)(H2O)] displays only one signal
at 9.71 ppm, supporting the presence of only one coordinated
PPh3 group [21].
3.4. Electronic spectra
The electronic spectra of the H2hna complexes were recorded in
DMF in the 200–800 nm regions. The bands appearing below
Cis-isomer
Trans-isomer
Fig. 4. Cis- and trans-isomers of [Pd(Hhna)2].
Fig. 5. 1H NMR spectrum of [Pd(Hhna)2].

S.A. Elsayed et al. / Journal of Molecular Structure 1036 (2013) 196–202
201
Table 3
Thermal analysis data of some complexes of H2hna.
Complex
Temp. range
70–130
250–350
400–500
500–600
600–800
Assignments
% Found (Calcd.)
Fragment loss
[Zn(Hhna)(H2O)2]ꢂH2O
Dehydration
Coordinated water
Degradation
Decomposition
Fusion
3.55 (3.7)
7.5 (7.9)
44.7 (44.6)
10.8 (9.7)
–
–H2O
–2H2Os
–C11H7O2, 1/2O2
–CO2
–
[Ag(Hhna)(H2O)2]2ꢂ2H2O
[Pd(Hhna)2]ꢂH2O
40–150
Dehydration
Coordinated water
Decomposition
Fusion
5.3 (5.2)
10.5 (10.3)
–
–
–2H2O
–2H2O
–
–
150–250
250–350
350–600
100
Dehydration
Degradation
Decomposition
Fusion
3.7 (3.6)
37.9 (37.6)
12.2 (12.1)
–
–H2O
150–400
400–600
600–800
–C11H7O2
–CO2 and ½O2
–
[Pd(bpy)(hna)]ꢂH2O
50–135
240–420
421–500
501–600
700
Dehydration
Degradation
Degradation
Decomposition
Oxide residue
3.6 (3.9)
–H2O
35.9 (36.4)
16.6 (16.7)
17.0 (16.7)
27.0 (26.2)
–C11H6O2
ꢀ1/2 bpy
ꢀ1/2 bpy
PdO
400 nm are assigned to intra-ligand charge-transfer (n ? ꢄ) and
( ? ꢄ) transitions. The electronic spectra of the complexes contain
intense bands due to ligand-to-metal charge-transfer (LMCT) and
weaker bands that can be assigned to d–d transitions [28].
The electronic spectra of the diamagnetic [Ag(Hhna)(H2O)2] and
[Ag(PPh3)(Hhna)] show bands near 440 and 375 nm; the latter may
arise from charge transfer transitions of the type ligand () ? b1g
tation patterns corresponding to the successive degradation of the
molecule. The first signal at m/z 479.0 (Calcd. 480.4) with 91.6%
abundance is in agreement with the molecular ion of the complex,
[Pd(Hhna)2]+. The spectrum exhibits signals assigned to COO and
O2 fragments loss at 437.0 (Calcd. 436.4) and 404.0 (Calcd.
404.4), respectively [26].
The mass spectrum of the complex, [Ag(Hhna)(H2O)2], shows a
signal at m/z 698.4 (Calcd. 698.0) with 11% abundance indicating
its dimeric nature {[Ag(Hhna)(H2O)2]2}. Finally, the mass spec-
trum of [Ag(Hhna)(PPh3)(H2O)] exhibits a peak at m/z 575.0
(Calcd. 575.0) with 2.6% abundance, corresponding to the
[Ag(Hhna)(PPh3)(H2O)]+ molecular ion. There is one more signal
at 369.4 (Calcd. 370.0) corresponding to [Ag(PPh3)]+.
(Ag+) and ligand ( ) ? b1g (Ag+) in a distorted square-planar envi-
r
ronment around the metal ion [29]. The electronic spectra of the
diamagnetic complexes, [Pd(Hhna)2], [Pd(bpy)(hna)], [Pd(phen)(h-
na)] and [Pt(PPh3)2(hna)] illustrate the square-planar environment
around the Pd(II) and Pt(II) ions. In the visible region, three spin-al-
lowed, singlet–singlet d–d transitions are predicted [29,30]. The
1
ground state is A1g and the excited states corresponding to three
1
transitions are A2g
,
1B1g and 1Eg in order of increasing energy.
3.6. TGA measurements
Strong charge-transfer transitions interfere and prevent observa-
tion of the expected bands. The absorption band near 360 nm is
assigned to a combination of charge-transfer transitions from the
Pd(II) or Pt(II) d-orbitals to the pꢄ-orbital of 2,20-bipyridyl, 1,
10-phenanthroline or triphenylphosphine and d-d bands, while
the band near 470 nm is attributed to a combination of ligand
The results of simultaneous TGA analyses of the complexes,
[Zn(Hhna)2(H2O)2]ꢂH2O, [Ag(Hhna)(H2O)2]2ꢂ2H2O, [Pd(Hhna)2]ꢂH2O
and [Pd(bpy)(hna)]ꢂH2O are reported in Table 3. In the complexes,
[Zn(Hhna)2(H2O)2]ꢂH2O, [Ag(Hhna)(H2O)2]2ꢂ2H2O and [Pd(Hhna)2]
ꢂH2O, abrupt weight loss observed in the temperature range 50–
170 °C and the corresponding endothermic peaks due to hydration.
This situation is responsible for the color of complexes changes
from light to deep. The hydration temperatures of the complexes
are almost the same, possibly due to the presence of the same
constituents and the similar Hhnaꢀ bidentate chelation through
the deprotonated carboxylato oxygen atoms. The IR spectra of
the hydrated and dehydrated complexes show no difference, indi-
cating that the water of hydration molecules play no role in the lat-
tice forces [32]. The sharp exothermic peaks within the
temperature ranges, 250–350, 450–500 and 520–600 °C, can be as-
signed to thermal degradation, partial decomposition, fusion and
vaporization [33,34]. The thermogram of [Pd(bpy)(hna)]ꢂH2O
shows thermal stability up to 240 °C with degradation character-
ized by four weight losses in the 50–135, 240–420, 421–500 and
501–600 °C regions. These weight losses are attributed to the elim-
ination of hydrated water (Calcd. 3.6, Found 3.9%), C11H6O2 (Calcd.
35.9, Found 36.4%), ½ bpy (Calcd. 16.6, Found 16.7%) and ½ bpy
(Calcd. 17.0, Found 16.7%) fragments, respectively, leaving PdO
(representing 26.2%) [35].
(p)-to-metal charge-transfer and M(II) d–d bands [30,31].
3.5. Mass spectra
Mass spectra of the complexes were measured and their molec-
ular ion peaks are in agreement with calculated formulae. In the
mass spectrum of [MoO2(hna)2]2ꢀ, the signal at m/z 500.0 (Calcd.
500.0) with 26% abundance is is associated with the molecular
ion, [MoO2(hna)2]+.
The mass spectrum of [Pt(PPh3)2(hna)] shows a signal at m/z
905.3 (Calcd. 905) with 46.4% abundance. The fragmentation pat-
terns indicates the stepwise ligand loss to [Pt(PPh3)2]+ (720) and
[Pt(PPh3)]+ (458) [26]. The mass spectra of [Pd(bpy)(hna)] and
[Pd(phen)(hna)] show peaks at m/z 449 (with 8.2% abundance)
and 473 (with 5.1% abundance), which represent the molecular
ions [Pd(bpy)(hna)]+ (Calcd. 448.4) and [Pd(phen)(hna)]+ (472.4),
respectively.
The mass spectrum of the complex, [Zn(Hhna)2(H2O)2], shows
fragmentation patterns corresponding to the successive degrada-
tion of the molecule. The first signal is observed at m/z 475.8
(Calcd. 475.5) with 11% abundance corresponding to [Zn(Hhna)2
(H2O)2]+. The signals at 439.0 (Calcd. 439.5) and 395.2 (Calcd.
395.5) are associated with [Zn(Hhna)2(H2O)2]+ and [Zn(Hhna)2]+,
respectively. The mass spectrum of [Pd(Hhna)2] displays fragmen-
4. Conclusion
In summary, the new 2-hydroxy-1-naphthoic acid (H2hna)
complexes, [Zn(Hhna)2(H2O)2], (PPh4)2[MoO2(hna)2], [Pd(Hhna)2],

202
S.A. Elsayed et al. / Journal of Molecular Structure 1036 (2013) 196–202
[7] C.F. Edwards, W.P. Griffith, A.J.P. White, D.J. Williams, J. Chem. Soc., Dalton
Trans. (1993) 3813–3819.
[8] K. Rissanen, J. Valkonen, P. Kokkonen, M. Leskela, Acta Chem. Scand. A41
(1987) 299–309.
[9] M. Kobza, A. Mrozek, J. Therm. Anal. Calorim. 96 (2009) 553–560.
[10] W.P. Griffith, S.I. Mostafa, Polyhedron 11 (1992) 871–877.
[11] R.C. Cookson, D.W. Jones, J. Chem. Soc. (1965) 1881–1892.
[12] W. Geary, Coord. Chem. Rev. 7 (1971) 81–122.
[13] M.M. Tamizh, K. Mereiter, K. Kirchner, B.R. Bhat, R. Karvembu, Polyhedron 28
(2009) 2157–2164.
[14] J.L. Li, Z.W. Gao, L.X. Gao, C.Y. Zhang, Z.-T. Liu, W. Tikkanen, J. Coord. Chem. 62
(2009) 1594–1603.
[15] M.S. Aksoy, R. Aydin, N. Turkel, U. Ozar, Chem. Pharm. Bull. 53 (2005) 471–475.
[16] J.N. Van Niekerk, F.R.L. Schoening, J.H. Talbot, Acta Crystallogr. 6 (1953) 720–
723;
N.W. Alcock, V.L. Tracy, Acta Crystallogr. 35B (1979) 80–83.
[17] E.F. Bertaut, T.Q. Due, P. Burlet, P. Burlet, M. Thomas, J.M. Moreau, Acta
Crystallogr. 30B (1974) 2234–2236;
[Pt(PPh3)2(hna)], [Pd(L)(hna)] (L = bpy, phen), [Ag(Hhna)(H2O)2]
and [Ag(Hhna)(PPh3)(H2O)], are reported. The X-ray crystal struc-
ture of [Pt(hna)(PPh3)2] has been determined. In the complexes,
(PPh4)2[MoO2(hna)2], [Pt(PPh3)2(hna)] and [Pd(L)(hna)] (L = bpy,
phen), hnaꢀ2 coordinates the metal ion in a binegative bidentate
manner through the deprotonated hydroxy and the deprotonated
carboxylate oxygen centers, while in the complexes, [Zn(Hhna)2
(H2O)2], [Pd(Hhna)2], [Ag(Hhna)(H2O)2] and [Ag(Hhna)(PPh3)
(H2O)], Hhnaꢀ behaves as mononegative bidentate through the
carboxylato oxygen atoms. The mass spectra of the complexes con-
firm their molecular formulae, while the TGA analyses reflect their
stability up to 250 °C.
Acknowledgements
J.E. Davies, B.M. Gatehouse, K.S. Murray, J. Chem. Soc., Dalton Trans. (1973)
2523–2527.
[18] C. Alyea, S.A. Dias, G. Ferguson, M.A. Khan, P.J. Roberts, Inorg. Chem. 18 (1979)
2433–2437.
[19] S.I. Mostafa, Transition Metal Chem. 32 (2007) 769–775.
[20] S.I. Mostafa, C. Papatriantafyllopoulou, S. Perlepes, N. Hadjiliadis, Bioinorg.
Chem. Appl. (2008). doi: 1155/2008/647873.
We are grateful to the Ministry of Higher Education in Egypt
(E.S.) and a Discovery grant (ISB) from the NSERC (Canada) for
the financial support of this work.
[21] A.K. Boudalis, V. Nastopoulos, S.P. Perlepes, C.P. Raptopoulou, A. Terzis,
Transition Metal. Chem. 26 (2001) 276–281.
[22] S.I. Mostafa, Transition Metal. Chem. 23 (1998) 397–401.
[23] K. Nakamoto, Infrared and Raman Sectra of Inorganic and Coordination
Compounds, fourth ed., Wiley, New York, 1986.
[24] Y.B. Koh, G.G. Christoph, Inorg. Chem. 17 (1978) 2590–2596.
[25] G.A. Barclay, C.H.L. Kennard, J. Chem. Soc. (1961) 3289–3294.
[26] I. Gabr, H. El-Asmy, M. Emmam, S.I. Mostafa, Transition Metal. Chem. 34
(2009) 409–418.
[27] S.I. Mostafa, Transition Metal. Chem. 24 (1999) 306–310.
[28] A.M. Ouf, M.S. Ali, E.M. Saad, S.I. Mostafa, J. Mol. Struct. 973 (2010) 69–75.
[29] S.I. Mostafa, F.A. Badria, Metal Based Drug. doi: http://dx.doi.org/10.1155/
2008/723634.
Appendix A. Supplementary material
CCDC 846523 contains the supplementary crystallographic data
of [Pt(hna)(PPh3)2]. Supplementary data associated with this arti-
cle can be found, in the online version, at http://dx.doi.org/
10.1016/j.molstruc.2012.09.018.
References
[30] S.I. Mostafa, J. Coord. Chem. 61 (2008) 1553–1567.
[31] A.M. Ouf, M.S. Ali, M.S. Soliman, A.M. El-Defrawy, S.I. Mostafa, J. Korean Chem.
Soc. 54 (2010) 402–410.
[32] Sh. Sallam, M. Ayad, J. Korean Chem. Soc. 47 (2003) 199–205.
[33] A. Donia, M. Ayad, R. Issa, Transition Metal Chem. 16 (1991) 518–520.
[34] A. Donia, M. Ayad, Monatsh. Chem. 124 (1993) 981–986.
[35] S.A. Elsayed, B. Jean-Claude, I.S. Butler, S.I. Mostafa, J. Mol. Struct. 1028 (2012)
208–214.
[1] J. Nan, R. Brad, M. Andrew, Org. Lett. 6 (2004) 4551–4553.
[2] M.I. Rodriguez-Cacere, R.A. Agbaria, U.J. Luna, S. White, I.M. Warner,
Spectrochim. Acta A 71 (2008) 907–914.
[3] D. Joshi, T.K. Joshi, E-J. Chem. 1 (2004) 110–114.
[4] L. Ding, J. He, J. Fu, J. Ahang, Spectrochim. Acta A 75 (2010) 604–609.
[5] A. Kula, J. Therm. Anal. Calorim. 68 (2002) 957–964.
[6] M.S. Aksoy, R. Aydin, N. Türkel, U. Özer, Chem. Pharm. Bull. 53 (2005) 471–475.