A palladium(II) complex containing both carbonyl and imine oxime ligands: Crystal structure, experimental and theoretical UV-vis, IR and NMR studies

Article abstract of DOI:10.1016/j.saa.2013.01.054

A new palladium(II) complex, [Pd(ppeieo)(inap)]·DMSO (ppeieo = (1E,2E)-phenyl-[(1-phenylethyl)imino]-ethanal oxime and inap = isonitrosoacetophenone) has been synthesized and characterized by elemental analysis, UV-vis, IR, NMR. X-ray diffraction analysis of the DMSO solvate of the complex shows that the palladium(II) ion is coordinated in a distorted square-planar geometry by ppeieo and inap, which is formed during the hydrolysis of ppeieo. DFT (B3LYP/LANL2DZ) calculations on the complex have been carried out to correlate geometry and spectroscopic properties such as electronic, vibrational and NMR chemical shifts. The complete vibrational frequency assignments were made and the calculation results were applied to simulate infrared spectra of the title compound which shows good agreement with observed spectra. The calculated HOMO and LUMO energies show that several transitions including the π → π and charge transfer occur within the molecule. The chemical shifts reasonably correspond to the calculated spectra.

Full text of DOI:10.1016/j.saa.2013.01.054

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 108 (2013) 133–140
Contents lists available at SciVerse ScienceDirect
Spectrochimica Acta Part A: Molecular and
Biomolecular Spectroscopy
journal homepage: www.elsevier.com/locate/saa
A palladium(II) complex containing both carbonyl and imine oxime ligands:
Crystal structure, experimental and theoretical UV–vis, IR and NMR studies
b
Yunus Kaya a, Ceyda Icsel a, Veysel T. Yilmaz a, , Orhan Buyukgungor
⇑
a Department of Chemistry, Faculty of Arts and Sciences, Uludag University, 16059 Bursa, Turkey
b Department of Physics, Faculty of Arts and Sciences, Ondokuz Mayis University, 55139 Samsun, Turkey
h i g h l i g h t s
g r a p h i c a l a b s t r a c t
A new palladium(II) complex with an imine oxime and carbonyl oxime has been synthesized and char-
acterized. This paper reports structural and spectroscopic characterization of the complex by using both
experimental methods such as X-ray, UV–vis, IR and NMR, and quantum chemical calculations.
"
"
"
"
A palladium(II) complex containing
imine and carbonyl oximes has been
synthesized.
The compound has been
characterized by UV–Vis, IR, NMR
and X-ray crystallography.
Theoretical UV–Vis, IR and NMR
spectra have been calculated using
DFT.
Theoretical calculations have been
compared with observed spectra.
a r t i c l e i n f o
a b s t r a c t
Article history:
A
new palladium(II) complex, [Pd(ppeieo)(inap)]ꢀDMSO (ppeieo = (1E,2E)-phenyl-[(1-phenyl-
Received 30 November 2012
Received in revised form 22 January 2013
Accepted 23 January 2013
Available online 1 February 2013
ethyl)imino]-ethanal oxime and inap = isonitrosoacetophenone) has been synthesized and characterized
by elemental analysis, UV–vis, IR, NMR. X-ray diffraction analysis of the DMSO solvate of the complex
shows that the palladium(II) ion is coordinated in a distorted square-planar geometry by ppeieo and inap,
which is formed during the hydrolysis of ppeieo. DFT (B3LYP/LANL2DZ) calculations on the complex have
been carried out to correlate geometry and spectroscopic properties such as electronic, vibrational and
NMR chemical shifts. The complete vibrational frequency assignments were made and the calculation
results were applied to simulate infrared spectra of the title compound which shows good agreement
with observed spectra. The calculated HOMO and LUMO energies show that several transitions including
Keywords:
Imine oxime
Carbonyl oxime
Palladium(II)
Crystal structure
DFT calculations
the
the calculated spectra.
p ?
pꢁ and charge transfer occur within the molecule. The chemical shifts reasonably correspond to
Ó 2013 Elsevier B.V. All rights reserved.
Introduction
great interest for many years [1–7]. The oxime and oximate species
display different coordination modes such as monodentate (N or
O), bidentate chelating (N, O) and bridging (N, O) [7–12]. Owing
to their coordination ability, they have been extensively used in
analytical chemistry for detection and separation of metal ions
[13–17]. Moreover, some oximes and their complexes have been
reported to have significant biochemical activity [18–24].
Oximes have often been used as chelating ligands in the field of
coordination chemistry and their metal complexes have been of
⇑
Corresponding author. Tel.: +90 224 2941749; fax: +90 224 2941898.
E-mail address: vtyilmaz@uludag.edu.tr (V.T. Yilmaz).
1386-1425/$ - see front matter Ó 2013 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.saa.2013.01.054

134
Y. Kaya et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 108 (2013) 133–140
In recent years, much attention has been given to theoretical
complex were obtained by the slow evaporation of the DMSO solu-
tion at room temperature within two days.
studies on oximes and their complexes. Experimental studies of
oximes and metal-oximes have been matched by theoretical calcu-
lations. Density functional theory (DFT) and other theoretical
methods provided geometry optimization of isomers [25–38],
and allowed to study reaction mechanisms [39–42] and spectro-
scopic properties (UV–vis, IR, Raman and NMR) [43–51] of some
oximes. On the other hand, synthesis of imine-oximes and their
complexes is one of the challenging areas in the field of the
oxime-coordination chemistry. Imineoximes containing schiff base
and oxime groups have been extensively studied because of their
biological and structural importance which lies mainly in their
specific and selective reactions with metal ions [52–57]. However,
theoretical studies of imine oximes and their metal complexes
have received less interest. Recently, we reported a combined
experimental and theoretical study of an imine oxime, namely
(1E,2E)-phenyl-[(1-phenylethyl)imino]-ethanal oxime (ppeieo)
[58]. The cisoid and transoid conformations of E- and Z-isomers of
this compound have been identified. In addition, electronic and
vibrational absorption bands have been characterized using DFT.
The first palladium(II) complex of oximes was [Pd(dmgH)2]
(dmgH = dimethylglyoximate) [59], while 3-hydroxyiminopen-
tane-2,4-dionato(pentane-2,4-dionato)palladium(II) and bis-(3-
hydroxyiminopentane-2,4-dionato)palladium(II) complexes were
the first examples of the palladium(II) complexes of imine oximes
[60]. In the present work, we report synthesis and crystal structure
of a palladium(II) complex, [Pd(ppeieo)(inap)]ꢀDMSO, containing
an imine oxime (ppeieo) together with a carbonyl oxime namely
isonitrosoacetophenone (inap). The results of the theoretical and
spectroscopic studies are presented. Theoretical data were calcu-
lated at the DFT/B3LYP level of theory. A complete vibrational anal-
ysis including corresponding assignments together with the PED
was performed by combining the measured and calculated data.
The UV–vis spectroscopic studies along with HOMO, LUMO analy-
sis have been used to elucidate electronic transitions within the
complex. Both calculated and experimental NMR chemical shifts
have been compared.
X-ray crystallography
The intensity data of the palladium(II) complex were collected
using a STOE IPDS 2 diffractometer with graphite-monochromated
Mo Ka radiation (k = 0.71069 Å). The structures were solved by di-
rect methods and refined on F2 with the SHELX-97 program [61].
All non-hydrogen atoms were found from the difference Fourier
map and refined anisotropically. All hydrogen atoms were posi-
tioned geometrically and refined by a riding model. The details of
data collection, refinement and crystallographic data are summa-
rized in Table 1.
Theoretical methods
All calculations were conducted using density functional theory
(DFT) as implemented in the GAUSSIAN 03 program package [62].
The geometry of the palladium(II) complex was fully optimized at
restricted B3LYP [63] and LANL2DZ level in the gas phase. The
atomic coordinates of the complex excluding the DMSO solvate
in the crystal structure were used for ab initio calculations. The
vibrational frequencies of the complex were calculated using the
same method. The frequency values computed at this level contain
known systematic errors and therefore, we have used a scaling fac-
tor:
A modified wavenumber-linear-scaling (WLS) approach
[64,65] was employed after completing the vibrational mode
assignment for complex. This method was derived by determining
the best-fit linear function between the experimental and theoret-
ical data. The resulting functions are shown in the following
equations:
y ¼ 0:7328x þ 682:47 ðR2 ¼ 0:98Þ for 4000—1700 cmꢃ1
y ¼ 1:0222x ꢃ 63:907 ðR2 ¼ 0:99Þ for 1700—250 cmꢃ1
ð1Þ
ð2Þ
Table 1
Crystallographic data and structure refinement for [Pd(ppeieo)(inap)]ꢀDMSO.
Experimental
Formula
C24H21N3O3PdC2H6OS
583.97
298(2)
0.71069 Å
Triclinic
Molecular weight
Temperature
Wavelength
Crystal system
Space group
Measurements
The elemental analyses (C, H and N) were performed using a
EuroEA 3000 CHNS elemental analyzer. UV–vis spectra were mea-
sured on a Perkin–Elmer Lambda 35 UV/vis spectrophotometer
using quartz cuvettes and 1 ꢂ 10ꢃ4 M DMSO solution in the 200–
800 nm range. IR spectra were recorded on a Thermo Nicolet
6700 FT-IR spectrophotometer as KBr (in the frequency range
ꢀ
P1
Unit cell dimensions
a (Å)
b (Å)
c (Å)
9.936(5)
11.701(5)
12.030(5)
a
b (°)
(°)
103.729(5)
100.791(5)
103.179(5)
1279.1(10)
2
4000–400 cmꢃ1) and CsI (in the frequency range 400–250 cmꢃ1
)
pellets. 1H NMR (400 MHz) and 13C NMR (100 MHz) spectra were
recorded on a Varian Mercury plus spectrometer in DMSO-d6 and
TMS was used as an internal standard.
c
(°)
Volume (Å3)
Z
Calculated density (g/cm3)
1.516
0.844
l
(mmꢃ1
)
F(000)
h range (°)
596
Synthesis of the palladium(II) complex
1.80–26.00
ꢃ12 6 h 6 12, ꢃ14 6 k 6 14,
ꢃ14 6 l 6 14
17204
5027 [Rint = 0.0664]
3469
Integration
0.9158 and 0.7757
5027/316
Index ranges
The imineoxime ligand was synthesized according to the proce-
dure described in the literature [58]. A solution of a ligand (0.126 g,
0.5 mmol) in ethanol (30 mL) was added drop wise with stirring to
a solution of Na2[PdCl4] (0.147 g, 0.5 mmol) in water (10 mL). The
mixture was stirred for 4 h at room temperature. The volume of the
solutions was reduced to 10–15 mL under vacuum and then the
resulting precipitate was filtered, and dried in air. Yield 83%. M.p.
Reflections collected
Independent reflections
Reflections observed (>2
Absorption correction
r
)
Max. and min. transmissions
Data/parameters
Goodness-of-fit on F2
0.818
Final R indices [I > 2
r
(I)]
R1 = 0.0327 wR1 = 0.0545
0.334 and ꢃ0.384
912128
141–143 °C
(decomp.);
Anal.
Calc.
for
C24H21N3O3Pd
Largest diff. peak and hole (e Åꢃ3
CCDC No
)
(505.9 g molꢃ1): C, 56.98; H, 4.18; N, 8.31. Found: C, 56.18; H,
4.42; N, 7.98%. X-ray quality orange crystals of the palladium(II)

Y. Kaya et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 108 (2013) 133–140
135
culated using TD-DFT with the B3LYP/LANL2DZ level. In addition,
the electronic absorption spectra were calculated in DMSO solution
using the IEFPCM method. Orbital contribution was analyzed using
GaussSum software [69].
Results and discussion
Molecular structure of [Pd(ppeieo)(inap)]ꢀDMSO
The X-ray and optimized structures of [Pd(ppeieo)(inap)]ꢀDMSO
are shown in Fig. 1. The title complex crystallizes in a triclinic
ꢀ
space group P1 as a DMSO solvate. The palladium(II) ion is coordi-
nated by two different oxime ligands, ppeieo and inap. As ex-
plained in Experimental, in the synthesis of the complex, the
ppeieo ligand was aimed to coordinate palladium(II). However, in
the presence of water, some of the imine oxime ligands were
hydrolyzed during the reaction, resulting in the products of a car-
bonyl oxime (inap) and the corresponding amine (Scheme 1). Such
imine bond (C@N) hydrolysis is common in the reactions of imines
and imine oximes [70–75]. Consequently, the ppeieo ligand to-
gether with the hydrolysis product (inap) coordinates to palla-
dium(II) forming a square-planar coordination geometry. The
ppeieo and inap ligands deprotonate to form the corresponding
monoanions. Ppeieo acts as a bidentate chelating ligand via two
N atoms, while inap behaves as a bidentate N, O donor. The com-
plex is also the first crystallographically studied palladium(II) com-
plex of the inap ligand. A palladium(II) complex with inap was
reported earlier, but its characterization was carried out from a
polycrystalline powder [76]. In addition, it was reported that the
ppeieo compound is chiral and its crystal structure contains both
enantiomers [58]. The crystal structure analysis of the title com-
plex shows the presence of the coordination of each enatiomers
of ppeieo to palladium(II). The individual molecules of the complex
were connected by two types of weak CAHꢀ ꢀ ꢀO hydrogen bonds
(Cꢀ ꢀ ꢀO = 3.26–3.39 Å) involving (i) the methyl hydrogen atoms of
DMSO molecules and oximate O atoms of imine- and carbonyl oxi-
mes in [Pd(ppeieo)(inap)] and (ii) phenyl hydrogens of carbonyl
oxime and O atoms of the DMSO molecules to form a two-dimen-
Fig. 1. Molecular views of [Pd(ppeieo)(inap)]ꢀDMSO. (a) X-ray structure and (b)
optimized structure (DMSO not included).
sional network (Fig. 2). It is interesting to note that no obvious p–p
stacking interactions between the phenyl rings of the ligands in the
The assignment of the calculated frequencies is aided by the anima-
tion option of GaussView 3.0 graphical interface for Gaussian pro-
grams, which gives a visual presentation of the shape of the
vibrational modes [66]. Furthermore, theoretical vibrational spectra
of the title compound were interpreted by means of PEDs using
VEDA 4 program [67].
adjacent molecules are present, but some phenyl hydrogens of
imine oxime participate to CAHꢀ ꢀ ꢀ
p
interactions (Cꢀ ꢀ ꢀCg = 3.73 Å,
where Cg is the centroid of the phenyl ring) with the phenyl ring
of the carbonyl oxime in the neighboring molecules.
The experimental and calculated bond distances and angles for
the coordination geometry around palladium(II) are listed in Ta-
ble 2. Generally, it is expected that the bond distances calculated
by electron correlated methods are longer than the experimental
distance. This situation is clearly observed as expected. The opti-
mized bond values deviate by 0.059 Å than those of the found val-
ues. This is consistent with the results obtained by the LANL2DZ/
B3LYP functional used in the calculation of metal complexes [77–
1H and 13C NMR chemical shifts (dH and dC) of complex were cal-
culated using the GIAO method [68] in DMSO at the B3LYP/
LANL2DZ level and using the TMS shielding calculated as a
reference.
Transition energies and oscillator strengths for electronic exci-
tation to the first 48 singlet excited states of the complex were cal-
CH3
CH3
H2N
2
O
N
N
EtOH/H2O
H3C
+
2HCl + 2NaCl
Pd
+
Na2[PdCl4]
+
25 oC, 4h
H
N
N
H
H
N
O
O
OH
Scheme 1. Synthesis reaction of [Pd(ppeieo)(inap)].

136
Y. Kaya et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 108 (2013) 133–140
Fig. 2. Packing of molecules of [Pd(ppeieo)(inap)].
Table 2
Selected geometric parameters of [Pd(ppeieo)(inap)].
Experimental
LANL2DZ
Bond lengths (Å)
C1AC2
C2AC3
1.422(4)
1.491(4)
1.505(4)
1.402(4)
1.478(4)
1.392(4)
1.386(4)
1.365(5)
1.375(5)
1.376(4)
1.379(4)
1.477(4)
1.293(4)
1.314(4)
1.267(3)
1.336(4)
1.259(3)
1.243(3)
2.034(3)
1.989(3)
2.014(3)
2.051(2)
1.436
1.497
1.546
1.420
1.482
1.416
1.404
1.409
1.410
1.403
1.416
1.484
1.332
1.351
1.313
1.366
1.284
1.280
2.081
2.034
2.065
2.110
C9AC10
C17AC18
C18AC19
C19AC20
C20AC21
C21AC22
C22AC23
C23AC24
C19AC24
C9AN2
C2AN2
C1AN1
C18AO3
C17AN3
N1AO1
N3AO2
Pd1AN2
Pd1AN1
Pd1AN3
Pd1AO3
Fig. 3. Experimental and calculated IR spectra of [Pd(ppeieo)(inap)].
82], On the other hand, both calculated and experimental bond an-
gles correlate well with each other within a difference of ca. 2°. The
PdAN(oxime) distances are 1.989(3) and 2.014(3) Å, being typical
of those found in palladium(II) complexes of oximes [9,11,59,83–
91].
Bond angles (°)
C1AC2AC3
C2AC3AC4
C3AC4AC5
C4AC5AC6
C5AC6AC7
C6AC7AC8
C3AC8AC7
C4AC3AC8
118.7(3)
117.4
121.4
120.4
120.2
119.7
120.2
120.4
119.1
119.5
122.9
124.2
117.1
125.5
122.5
116.8
110.7
109.4
114.2
118.1
116.0
119.0
120.5
80.2
121.4(3)
120.5(4)
120.1(3)
119.9(3)
120.7(4)
119.9(3)
119.0(3)
119.6(3)
122.3(3)
122.1(3)
116.3(3)
125.1(3)
122.3(3)
117.1(3)
108.7(3)
109.8(3)
116.0(3)
118.1(3)
115.7(3)
119.6(3)
120.8(3)
80.3(11)
101.1(12)
79.9(10)
98.8(10)
177.2(11)
178.7(11)
Vibrational spectra
Vibrational assignments were carried out with support of DFT
calculations using the B3LYP method with a LANL2DZ basis set
having the structural geometry obtained by the same method.
The calculated values were scaled as explained in the theoretical
methods. The observed and calculated vibrational spectra are given
in Fig. 3, while the corresponding frequencies along with the
assignments and intensities are given in Table 3. In general, the
absorption frequencies obtained from experiment and theory are
in good agreement.
C2AC3AC8
C17AC18AC19
C2AN2AC9
C1AC2AN2
C3AC2AN2
C1AN1AO1
C2AC1AN1
C11AC9AN2
C10AC9AN2
C11AC9AC10
C19AC18AO3
C18AC17AN3
C17AC18AO3
C17AN3AO2
N1APd1AN2
N1APd1AN3
N3APd1AO3
N2APd1AO3
N2APd1AN3
N1APd1AO3
Six CH stretching bands were observed in the spectrum of the
complex and four of which belongs to the phenyl rings. They ap-
peared as weak bands in the frequency range 2929–3067 cmꢃ1
.
Significant vibration bands of the ligands and their metal com-
plexes may be used for determining the ligands’ mode of coordina-
tion by the comparative analysis of the spectra of the ligand and
the complex, in particular in relation to the changes observed after
complexation. As reported earlier, the imine group (C@N) of ppeieo
appeared at 1612 cmꢃ1 and as shown in Table 3, after coordination,
100.7
79.1
100.0
179.0
178.1

Y. Kaya et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 108 (2013) 133–140
137
Table 3
Experimental FT-IR and DFT-B3LYP/LANL2DZ calculated spectra for [Pd(ppeieo)(inap)] together with their assignmenta (wavenumber in cmꢃ1).
Experimental
Unscaled
Scaled
Intensity
Assignment (PED > 10)
3067w
3058w
3244
3236
3233
3223
3222
3221
3214
3213
3137
3058
3049
1652
1651
1557
1542
1534
1523
1520
1503
1495
1482
1476
1469
1442
1439
1433
1407
1384
1383
1360
1356
1284
1279
1266
1261
1239
1226
1224
1173
1149
1115
1108
1090
1067
1051
1048
1041
1039
977
3060
3054
3052
3044
3044
3043
3038
3037
2981
2923
2917
1625
1624
1528
1512
1504
1493
1490
1472
1464
1451
1445
1438
1410
1407
1401
1374
1351
1350
1326
1322
1249
1243
1230
1225
1203
1189
1187
1135
1111
1076
1069
1050
1027
1010
1007
1000
998
120,205
232,840
206,844
328,291
366,235
187,327
302,836
207,925
403,348
318,787
138,754
266,285
150,376
567,187
1,243,660
99,591
333,205
175,256
3,277,110
3,120,560
2,516,170
111,177
985,217
912,799
368,462
1,085,240
497,930
128,332
182,300
51,496
149,572
874,062
2,175,080
222,886
542,050
126,014
54,629
120,899
145,115
185,274
205,823
63,406
86,715
50,599
52,811
107,854
92,821
m
m
m
m
m
m
m
m
m
m
m
m
m
m
m
CHphen. (87)
CHphen. (90)
CHphen. (97)
CHphen. (98)
CHphen. (86)
CHphen. (89)
CHphen. (91)
CHphen. (97)
3028w
2974w
2929w
CHmeth. asym. (100)
CHmeth. sym. (95)
CHCHNO (94)
1632m
CO (22),
CCphen. (28)
CN (51), CCphen. (12)
CCphen. (28), dCHphen. (21)
mCCphen. (37)
1623m
1598m
m
dCHmeth. (81)
dCHmeth. (25)
dCHphen. (24), mCN (11), dCHmeth. (13)
1493s
1455s
mCCphen. (20), dCHphen. (26)
mCN (18), CCphen. (19), dCHCHNO(19)
m
1419w
1396w
dCHphen. (29), dCHCHNO(13)
CCphen. (21), dCHCHNO(50)
dCHphen. (34)
CO (31), dCHmeth. (10)
dCHmeth. (40)
m
m
m
m
m
CO (44)
NO (45)
CCphen. (62), dCHphen. (10)
dCHCHNC (46)
1271w
m
m
m
m
m
CCphen. (10), dCHphen. (33)
CCphen. (20), dCHphen. (36)
CN (35), dCHCHNO (24), dNCC (16)
NO (10),
NO (22),
1244w
1228s
m
m
CAC (19), dCHCHNO (32)
CAC (21), dCHCHNO (14)
vCN (60)
CAC (33)
1179w
m
dCHphen. (74)
dCHphen. (72)
mCAC (15),
m
CAN (24), dCHphen. (10)
CNCC (10)
CCphen. (15)
CCphen. (35)
cCHmeth. (31),
c
m
m
dCHphen. (42),
dCHphen. (23),
dCHmeth. (23)
m
m
m
CAC (17)
CAC (23)
CCphen. (34), dCCphen. (14)
1019m
997m
962m
921w
dCHphen. (12)
dCHphen. (47)
mCAC (10), dCHphen. (44)
78,515
78,102
935
966
924
87,684
dCHphen. (77)
902
852
838
831
823
814
801
767
729
727
718
699
696
690
858
807
793
786
777
768
755
720
681
679
670
651
648
641
301,434
176,424
316,565
109,838
189,056
722,984
610,124
644,387
528,170
334,086
518,365
244,743
186,478
85,159
dNCC (27), dCCphen. (10)
dCHCHNO (66)
dCHCHNO (61), dOPdCN (11), dCNCC (13)
dCCphen. (22)
768m
dCCphen. (22), sHCCN (10)
744w
699s
dCHphen. (47), dCHCHNO (15)
dCHphen. (42), dCHCHNO (19)
dCHphen. (36)
dCHphen. (29), dCCphen. (60)
dCHphen. (34), dCCphen. (62)
dCHphen. (43), dCCphen. (49)
670m
m
m
PdO (21), dOCC (10), dCCphen. (21)
PdN (17), dOCC (30), dCCphen. (21)
651w
dCCphen. (12)
617vw
611
538
531
511
561
486
479
458
80,144
184,806
73,903
112,114
82,828
m
m
PdN (22), dONC (40)
PdO (16), dNCC (14)
536vw
463w
dCNCC (28)
PdN (12), dCCphen. (27)
m
479
426
dOPdCN (48)
452
398
54,153
dPdCN (14), dNCC (17)
332w
438
267
384
209
100,612
323,570
m
m
PdN (14), dCCphen. (14), dCNCC (18)
PdN (20), dPdCN (14)
a
w = weak, vw = very weak, s = strong, m = medium;
m
= streching, d = in-plane bending, c = out-of- plane bending.

138
Y. Kaya et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 108 (2013) 133–140
Table 4
Experimental and calculated electronic transitions, oscillator strengths and their assignments for [Pd(ppeieo)(inap)]a.
Major contribution(CI coeff)
Character
Calculated
Experimental
k (nm)
D
E (eV)
fos
k (nm)
D
E (eV)
e
H-1 ? L + 2 (%35)
H-2 ? L (44%)
H ? L + 1 (23%)
H-6 ? L(22%)
H ? L + 1 (23%)
H-5 ? L + 1(40%)
H-11 ? L (12%)
H-13 ? L (23%)
H-6 ? L + 1 (55%)
H-6 ? L + 2 (19%)
H-11 ? L + 1 (20%)
H-9 ? L + 2 (14%)
d(Pd)/
p
(oxime) ? d(Pd)/pꢁ(oxime)
416
388
2.99
3.20
0.07
0.09
p
p
p
p
p
(carbonyloxime) ? pꢁ(carbonyloxime)
414
346
3.00
3.59
4740
9240
(imineoxime) ? pꢁ(imineoxime)
(pheyl) ? pꢁ(carbonyloxime)
(imineoxime) ? pꢁ(imineoxime)
(oxime) ? pꢁ(imineoxime)
358
3.47
0.27
354
307
301
297
269
261
3.51
4.05
4.13
4.18
4.62
4.76
0.11
0.14
0.08
0.12
0.06
0.16
d(Pd)/
d(Pd)/
p
p
(oxime) ? pꢁ(carbonyloxime)
(carbonyl) ? pꢁ(carbonyloxime)
p
p
(phenyl) ? pꢁ(imineoxime)
(phenyl) ? d(Pd)/pꢁ(oxime)
d(Pd)/
d(Pd)/
p
p
(oxime) ? pꢁ(imineoxime)
289
4.30
22950
(carbonyl) ? d(Pd)/pꢁ(oxime)
a
e
= Molar absorption coefficient (dm3 molꢃ1 cmꢃ1), fos = Oscillator strength, H = Highest occupied molecular orbital, L = Lowest unoccupied molecular orbital.
Fig. 4. Experimental and calculated electronic spectra of [Pd(ppeieo)(inap)].
a 11 cmꢃ1 shift in the wave number of the imine
m(C@N) band (at
1623 cmꢃ1) is observed and indicates a stronger double bond char-
acter of the imine bond. On the other hand, the stretching mode of
the oxime
m
(C@N) group occurs at ca. 1598 cmꢃ1 in the free ppeieo
and inap ligands and is shifted by 100 cmꢃ1 in the palladium(II)
complex. Experimental value of this absorption band (1493 cmꢃ1
)
well agrees with the calculated value of 1490 cmꢃ1. Such a large
shift was reported for the oxime C@N stretching band of the palla-
dium(II) complex of the inap ligand [76]. Moreover, compared to
that of the free inap ligand, a significant shift (ca. 36 cmꢃ1) to the
lower frequency of the m(C@O) band was observed in the present
complex as a consequence of coordination through the carbonyl
group. A number of C@C and CAC stretching bands with different
intensities appeared between 1600 and 1100 cmꢃ1. However, the
calculated vibrational frequencies significantly deviate from the
experimental values, probably as coupling with other vibrational
modes (Table 3). A substantial change is also observed in the
NAO stretchings which appears at 985 and 1022 cmꢃ1 in free inap
and ppeieo ligands, respectively. In the palladium(II) complex,
these bands occurred at 1228 cmꢃ1 (calcd. 1243 cmꢃ1), indicating
an increase in the double bond character of the NO bond due to
the loss of the hydroxyl hydrogen. This unexpected shift in the
NAO frequency is consistent with those of the reported palla-
dium(II) complexes of oximes [9,76]. Vibrational modes in the
low wavenumber region of the spectrum contain
(PdAO) stretchings together with contributions of several modes.
The title complex shows a band at 670 cmꢃ1, which can be attrib-
uted to
(PdAO) (calcd. 651 cmꢃ1), while the three bands at 617,
463 and 332 cmꢃ1 are assigned to
(PdAN). The calculated
(PdAN) modes were found between 561 and 384 cmꢃ1
m(PdAN) and
Fig. 5. The transitions responsible for the electronic absorptions in
[Pd(ppeieo)(inap)].
m
m
m
their assignments as well as the experimental results are given in
Table 4. The absorption bands of the title complex appear at
around 289, 346, and 414 nm (Fig. 4). To understand the transition
processes, the calculated absorption transition diagram is shown in
Fig. 5. The high energy absorption at 289 nm is contributed by the
electron excitation from HOMOꢃ11 to LUMO+1 (29%) and
HOMOꢃ9 to LUMO+2 (14%) at 261 nm with oscillator strength of
m
.
UV–vis spectra
The calculated absorptions of the palladium(II) complex associ-
ated with their oscillator strengths, the main configurations, and

Y. Kaya et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 108 (2013) 133–140
139
same as in Fig. 1. In some cases, the NMR spectrum is not well cor-
related with the calculated spectrum, since calculations are re-
ferred to the static molecule [92,93]. The CH moiety adjacent to
the oximate groups resonances over 8 ppm, but it appears at
7.88 ppm in the spectrum of the ppeieo ligand [58], indicating
the deshielding of this proton after coordination. The signals be-
tween 7.18 and 7.73 ppm are assigned to aromatic protons, while
the doublet at 1.84 ppm is attributed to the methyl protons. In
the 13C NMR spectrum, the signal at 175.9 ppm belongs to the car-
bonyl C carbon atom and was calculated at 190.9 ppm, while the
signals at 139.6 and 142.0 ppm are assigned to the C@NAO groups
of the ppeieo and inap ligands, respectively. The signals between
126.2 and 135.1 ppm are assigned to the phenyl carbon atoms of
ppeieo and inap. The chemical shifts of the C9 and C10 (methyl
C) atoms are observed at 60.1 and 19.9 ppm, respectively and were
calculated at 14.5 and 60.1 ppm, respectively.
Conclusions
In this study, a palladium(II) complex, namely [Pd(ppeieo)(i-
nap)], has been synthesized and characterized by various tech-
niques including elemental analysis, UV–vis, IR and NMR. X-ray
crystallographic analysis of the complex shows that the palla-
dium(II) ion is coordinated by both imine and carbonyl oxime li-
gands which behave as bidentate ligands. In order to study
electronic, vibrational and NMR properties of the palladium(II)
complex, the theoretical calculations were successfully performed
by using DFT with the B3LYP/LANL2DZ level. The calculated data
were in agreement with the observed data. This systematic study
may be useful for the analysis of the spectroscopic behavior of
coordination compounds of other imine and carbonyl oximes.
Acknowledgements
This work is a part of a Research Project OUAP(F)-2012/12. We
thank Uludag University for the financial support given to the
project.
Appendix A. Supplementary material
Supplementary data associated with this article can be found, in
the online version, at http://dx.doi.org/10.1016/j.saa.2013.01.054.
Fig. 6. Experimental and calculated NMR spectra of [Pd(ppeieo)(inap)].
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