research communications
E)-(4-fluorobenzyl)imino]ethyl}phenolato-κ2N,O)palladium(II)
of bis(2-{1-[(aFaculty of Applied Sciences, Universiti Teknologi MARA, 40450 Shah Alam, Selangor, Malaysia, bDDH CoRe, Universiti Teknologi MARA, 40450 Shah Alam, Selangor, Malaysia, cInstitute of Science, Universiti Teknologi MARA, 40450 Shah Alam, Selangor, Malaysia, and dDepartment of Chemistry, Faculty of Science, Prince of Songkla University, Hat-Yai, Songkhla 90112, Thailand
*Correspondence e-mail: hadariah@salam.uitm.edu.my
The 15H13FNO)2], contains one half of the molecule with the PdII cation lying on an inversion centre and is coordinated by the bidentate Schiff base anion. The geometry around the cationic PdII centre is distorted square planar, chelated by the imine N- and phenolate O-donor atoms of the two Schiff base ligands. The N- and O-donor atoms of the two ligands are mutually trans, with Pd—N and Pd—O bond lengths of 2.028 (2) and 1.9770 (18) Å, respectively. The fluorophenyl ring is tilted away from the coordination plane and makes a dihedral angle of 66.2 (2)° with the phenolate ring. In the crystal, molecules are linked into chains along the [101] direction by weak C—H⋯O hydrogen bonds. Weak π–π interactions with centroid–centroid distances of 4.079 (2) Å stack the molecules along c.
of the title complex, [Pd(CKeywords: crystal structure; PdII complex; NO donors; Schiff base; catalyst activity; hydrogen bonding; π–π interactions.
CCDC reference: 1045879
1. Chemical context
). The PdII and NiII complexes of have attracted much attention as they play important roles in bioinorganic chemistry and may provide the basis for models of active sites of biological systems (Malik et al., 2013) or act as catalysts (Shahnaz et al., 2013). The title compound, [Pd(C15H13FNO)2], is related to the previously reported compound bis{2-[(E)-(4-fluorobenzyl)iminomethyl]phenolato-κ2N,O1}nickel(II) (Mohd Tajuddin et al., 2014) in terms of the coordination geometry around the central metal. In this article, we report the synthesis of the title Schiff base–PdII complex and its characterization by spectroscopy and elemental analysis. The X-ray structure (Fig. 1), confirms the binding mode of the 4-fluorobenzyl(iminoethyl)phenolate ligand to the PdII cation.
represent one of the most widely utilized classes of ligands in coordination chemistry and the chemistry of is still an area of increasing interest (Canali & Sherrigton, 1999The title compound (1) was screened for
in the Suzuki cross-coupling reaction between phenylboronic acid and iodobenzene with a catalyst loading of 1 mmol%. The conversion of iodobenzene was found to occur with a yield of 52%.2. Structural commentary
The II cation lying on an inversion centre and the Schiff base anion acting as an N,O bidentate chelate ligand (Fig. 1). The PdII cation binds to the N and the O atoms of two symmetry-related Schiff base ligand such that the N and O atoms are mutually trans. The N2O2 donor sets of the two chelating Schiff base ligands in the equatorial plane around Pd1 adopt a slightly distorted square-planar coordination geometry. The Pd1—N1 and Pd1—O1 distances (Table 1) are typical of square-planar PdII complexes, and compare well with those observed in other closely related PdII complexes (Adrian et al., 2008; Bahron et al., 2014; Wan Ibrahim & Shamsuddin, 2012). The bite angle of the iminomethylphenolate chelate, N1—Pd1—O1 is 88.48 (8)°, which is also similar to that in a related PdII complex (Bahron et al., 2014). The ring Pd1/N1/C8/C9/C10/O1 adopts an with Pd1 displaced by 0.270 (2) Å from the plane of the other ring atoms, and with puckering parameters Q = 0.525 (2) Å, θ = 112.8 (3) and φ = 206.9 (3)°. Other bond lengths and angles observed in the structure are also normal. The fluorophenyl ring (C1–C6) makes a dihedral angle of 66.2 (2)° with the phenolate ring (C9–C14).
of (1) contains one-half of the molecule with the Pd3. Supramolecular features
In the crystal packing of (1), the molecules are linked into chains along the [101] direction by weak C4—H4A⋯O1 interactions (Fig. 2, Table 2). A weak π–π stacking interaction occurs between the phenolate rings of adjacent complexes (Fig. 3), with a centroid–centroid distance, Cg4⋯Cg4iii, of 4.079 (2) Å [symmetry code: (iii) = 1 − x, 2 − y, 1 − z; Cg4 is the centroid of the C9–C14 ring]. These combine with the C—H⋯O contacts to generate sheets in the ac plane (Fig. 4). These sheets are further stacked along the b-axis direction.
4. Database survey
Six PdII complexes with related Schiff base N2O2 donor sets have been reported (Brunner et al., 2000; Mehta & Vengurlekar, 2001; Bahron et al., 2011, 2014; Mohd Tajuddin et al., 2012a; Tsuno et al., 2013). However, only three of these PdII complexes have closely related Schiff base ligands (Bahron et al., 2011; 2014; Mohd Tajuddin et al., 2012a).
5. Synthesis and crystallization
The ligand, (E)-2-(1-(4-fluorobenzylimino)ethyl)phenol (Mohd Tajuddin et al., 2012b) (2 mmol, 0.4877 g) was dissolved in CH3CN (30 mL) in a round-bottomed flask. Palladium(II) acetate (1 mmol, 0.2251 g) was dissolved separately in CH3CN (20 mL) and was then added into the flask containing the ligand solution. The mixture was stirred and refluxed for 5 h upon which a turmeric yellow solid was formed. The solid was filtered off, washed with ice-cold CH3CN and air dried at room temperature. The solid product was recrystallized from chloroform, yielding yellow crystals (yield 48.5%). 1H NMR, 13C NMR and IR spectral bands have been studied and agree well with the structure obtained from the values of the CHN analyses and X-ray structure determination.
Melting point 508–510 K. Analytical data for C30H26F2N2O2Pd: C, 60.97; H, 4.43; N, 4.74%; Found: C, 60.81; H, 4.49; N, 4.66%. IR (KBr, cm−1): 1598 ν(C=N), 1319 ν(C—N), 1216 ν(C—O), 1321 ν(CH3), 556 ν(Pd—N), 450 ν(Pd—O). 1H NMR (300 MHz, CDCl3): δ (p.p.m.) 2.32 (s, 3H, C—CH3), 5.11 (s, 2H, CH2), 6.53–7.46 (ArC). 13C NMR (300 MHz, CDCl3): δ (p.p.m.) 19.5 (C—CH3), 54.2 (CH2), 115.3, 115.6, 121.3, 128.6, 130.2 (ArC), 169.8 (C=N).
The infrared spectrum of (1) exhibits a strong band at 1598 cm−1 assignable to the C=N stretching frequency of the azomethine moiety. Weak bands at 556 and 450 cm−1 attributable to Pd—N and Pd—O vibrations, respectively (Ouf et al., 2010), are due to the participation of the nitrogen of the azomethine group and the oxygen of the phenolate ring in the complexation of the palladium(II) centre by the Schiff base ligands. From the NMR results, the free 4-fluorobenzyl(iminoethyl)phenolate ligand shows a multiplet at around 6.80–7.57 p.p.m. assignable to the aromatic protons. A corresponding multiplet appears in almost the same position in the spectrum of the PdII complex (compound 1) as that observed by Gupta et al. (2013). Singlets for aliphatic methylene (–CH2) and methyl (–CH3) protons appear at 5.11 and 2.32 p.p.m., respectively. The 13C for the imine carbon (C=N) is found at 169.8 p.p.m., agreeing with data reported by Şenol et al. (2011).
The title compound was screened for
in the Suzuki cross-coupling reaction between phenylboronic acid with iodobenzene. The reaction was carried out under nitrogen at 373 K in dimethylacetamide with a catalyst loading of 1 mmol%. The conversion of iodobenzene was monitored using GC–FID after 24 hours of reaction time. This resulted in a 52% conversion of iodobenzene in the reaction.6. Refinement
Crystal data, data collection and . All H atoms were positioned geometrically and allowed to ride on their parent atoms, with d(C—H) = 0.93 Å for aromatic, 0.97 Å for CH2 and 0.96 Å for CH3 hydrogen atoms. The Uiso values were constrained to be 1.5Ueq of the for methyl H atoms and 1.2Ueq for the remaining H atoms. A rotating group model was used for the methyl groups.
details are summarized in Table 3Supporting information
CCDC reference: 1045879
10.1107/S2056989015004405/sj5444sup1.cif
contains datablocks global, I. DOI:Structure factors: contains datablock I. DOI: 10.1107/S2056989015004405/sj5444Isup2.hkl
Data collection: APEX2 (Bruker, 2009); cell
APEX2 (Bruker, 2009); data reduction: SAINT (Bruker, 2009); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008), PLATON (Spek, 2009), Mercury (Macrae et al., 2006) and publCIF (Westrip, 2010).[Pd(C15H13FNO)2] | F(000) = 600 |
Mr = 590.93 | Dx = 1.539 Mg m−3 |
Monoclinic, P21/c | Melting point = 508–510 K |
Hall symbol: -P 2ybc | Mo Kα radiation, λ = 0.71073 Å |
a = 7.5924 (5) Å | Cell parameters from 2776 reflections |
b = 21.9212 (14) Å | θ = 3.2–27.0° |
c = 9.3475 (5) Å | µ = 0.77 mm−1 |
β = 124.963 (4)° | T = 296 K |
V = 1274.97 (15) Å3 | Block, yellow |
Z = 2 | 0.50 × 0.25 × 0.25 mm |
Bruker APEXII CCD area-detector diffractometer | 2776 independent reflections |
Radiation source: sealed tube | 2720 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.057 |
φ and ω scans | θmax = 27.0°, θmin = 3.2° |
Absorption correction: multi-scan (SADABS; Bruker, 2009) | h = −9→9 |
Tmin = 0.699, Tmax = 0.830 | k = −28→28 |
38866 measured reflections | l = −11→11 |
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.034 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.073 | H-atom parameters constrained |
S = 1.30 | w = 1/[σ2(Fo2) + (0.0086P)2 + 1.3994P] where P = (Fo2 + 2Fc2)/3 |
2776 reflections | (Δ/σ)max < 0.001 |
170 parameters | Δρmax = 0.24 e Å−3 |
0 restraints | Δρmin = −0.48 e Å−3 |
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes. |
Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > 2sigma(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger. |
x | y | z | Uiso*/Ueq | ||
Pd1 | 0.5000 | 1.0000 | 1.0000 | 0.03202 (9) | |
F1 | 1.3139 (4) | 0.77987 (11) | 1.2186 (5) | 0.1153 (11) | |
O1 | 0.5384 (3) | 1.04581 (9) | 0.8375 (2) | 0.0462 (5) | |
N1 | 0.4268 (3) | 0.92521 (9) | 0.8478 (3) | 0.0343 (4) | |
C1 | 0.7655 (7) | 0.78728 (16) | 1.0865 (7) | 0.0924 (16) | |
H1A | 0.6670 | 0.7629 | 1.0890 | 0.111* | |
C2 | 0.9701 (7) | 0.76567 (18) | 1.1567 (8) | 0.117 (2) | |
H2A | 1.0108 | 0.7272 | 1.2078 | 0.140* | |
C3 | 1.1113 (6) | 0.80149 (15) | 1.1502 (6) | 0.0716 (11) | |
C4 | 1.0618 (5) | 0.85845 (14) | 1.0834 (4) | 0.0495 (7) | |
H4A | 1.1627 | 0.8827 | 1.0839 | 0.059* | |
C5 | 0.8555 (5) | 0.87966 (12) | 1.0140 (4) | 0.0416 (6) | |
H5 | 0.8184 | 0.9188 | 0.9670 | 0.050* | |
C6 | 0.7048 (5) | 0.84467 (12) | 1.0125 (4) | 0.0411 (6) | |
C7 | 0.4795 (5) | 0.86633 (12) | 0.9399 (4) | 0.0429 (6) | |
H7A | 0.3781 | 0.8358 | 0.8598 | 0.051* | |
H7B | 0.4629 | 0.8702 | 1.0349 | 0.051* | |
C8 | 0.3497 (4) | 0.92650 (12) | 0.6831 (4) | 0.0382 (6) | |
C9 | 0.2963 (4) | 0.98338 (13) | 0.5855 (3) | 0.0381 (6) | |
C10 | 0.3929 (4) | 1.03958 (13) | 0.6678 (3) | 0.0390 (6) | |
C11 | 0.3352 (6) | 1.09165 (15) | 0.5625 (4) | 0.0527 (7) | |
H11A | 0.3971 | 1.1289 | 0.6147 | 0.063* | |
C12 | 0.1898 (6) | 1.08905 (16) | 0.3845 (4) | 0.0578 (8) | |
H12A | 0.1554 | 1.1243 | 0.3181 | 0.069* | |
C13 | 0.0945 (5) | 1.03431 (17) | 0.3037 (4) | 0.0551 (8) | |
H13A | −0.0052 | 1.0326 | 0.1833 | 0.066* | |
C14 | 0.1479 (5) | 0.98286 (15) | 0.4023 (4) | 0.0482 (7) | |
H14A | 0.0844 | 0.9461 | 0.3468 | 0.058* | |
C15 | 0.3123 (6) | 0.86788 (14) | 0.5833 (4) | 0.0566 (8) | |
H15A | 0.3280 | 0.8756 | 0.4900 | 0.085* | |
H15B | 0.1698 | 0.8531 | 0.5359 | 0.085* | |
H15C | 0.4154 | 0.8378 | 0.6608 | 0.085* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Pd1 | 0.03017 (15) | 0.03263 (14) | 0.03135 (14) | −0.00387 (10) | 0.01650 (11) | −0.00210 (11) |
F1 | 0.0547 (14) | 0.0598 (14) | 0.175 (3) | 0.0194 (11) | 0.0329 (16) | 0.0054 (16) |
O1 | 0.0568 (12) | 0.0479 (11) | 0.0349 (10) | −0.0199 (9) | 0.0269 (9) | −0.0048 (8) |
N1 | 0.0332 (11) | 0.0332 (10) | 0.0370 (11) | −0.0041 (8) | 0.0203 (9) | −0.0044 (9) |
C1 | 0.062 (2) | 0.0424 (19) | 0.143 (4) | −0.0064 (17) | 0.041 (3) | 0.027 (2) |
C2 | 0.066 (3) | 0.042 (2) | 0.183 (6) | 0.0083 (19) | 0.036 (3) | 0.038 (3) |
C3 | 0.0486 (19) | 0.0420 (17) | 0.089 (3) | 0.0076 (15) | 0.0185 (19) | −0.0048 (17) |
C4 | 0.0444 (16) | 0.0509 (17) | 0.0489 (17) | 0.0005 (13) | 0.0242 (14) | −0.0016 (13) |
C5 | 0.0495 (16) | 0.0367 (13) | 0.0406 (14) | 0.0042 (12) | 0.0269 (13) | 0.0054 (11) |
C6 | 0.0476 (15) | 0.0316 (12) | 0.0381 (14) | −0.0029 (11) | 0.0211 (12) | −0.0027 (11) |
C7 | 0.0504 (16) | 0.0328 (13) | 0.0514 (16) | −0.0084 (11) | 0.0327 (14) | −0.0041 (12) |
C8 | 0.0335 (13) | 0.0426 (14) | 0.0395 (14) | −0.0059 (11) | 0.0215 (12) | −0.0100 (11) |
C9 | 0.0350 (13) | 0.0478 (15) | 0.0337 (13) | −0.0014 (11) | 0.0209 (11) | −0.0032 (11) |
C10 | 0.0424 (14) | 0.0460 (15) | 0.0363 (14) | −0.0025 (12) | 0.0271 (12) | −0.0016 (11) |
C11 | 0.067 (2) | 0.0483 (17) | 0.0498 (18) | −0.0012 (15) | 0.0373 (17) | 0.0029 (13) |
C12 | 0.065 (2) | 0.062 (2) | 0.0513 (18) | 0.0141 (16) | 0.0365 (17) | 0.0169 (16) |
C13 | 0.0447 (17) | 0.079 (2) | 0.0360 (15) | 0.0042 (16) | 0.0197 (13) | 0.0037 (15) |
C14 | 0.0422 (15) | 0.0614 (18) | 0.0375 (15) | −0.0046 (13) | 0.0208 (13) | −0.0066 (13) |
C15 | 0.070 (2) | 0.0485 (17) | 0.0523 (18) | −0.0102 (15) | 0.0360 (17) | −0.0160 (14) |
Pd1—O1 | 1.9770 (18) | C6—C7 | 1.510 (4) |
Pd1—O1i | 1.9770 (18) | C7—H7A | 0.9700 |
Pd1—N1i | 2.028 (2) | C7—H7B | 0.9700 |
Pd1—N1 | 2.028 (2) | C8—C9 | 1.458 (4) |
F1—C3 | 1.369 (4) | C8—C15 | 1.516 (4) |
O1—C10 | 1.321 (3) | C9—C14 | 1.411 (4) |
N1—C8 | 1.297 (3) | C9—C10 | 1.415 (4) |
N1—C7 | 1.474 (3) | C10—C11 | 1.403 (4) |
C1—C2 | 1.378 (6) | C11—C12 | 1.373 (5) |
C1—C6 | 1.381 (4) | C11—H11A | 0.9300 |
C1—H1A | 0.9300 | C12—C13 | 1.381 (5) |
C2—C3 | 1.358 (6) | C12—H12A | 0.9300 |
C2—H2A | 0.9300 | C13—C14 | 1.363 (5) |
C3—C4 | 1.349 (5) | C13—H13A | 0.9300 |
C4—C5 | 1.387 (4) | C14—H14A | 0.9300 |
C4—H4A | 0.9300 | C15—H15A | 0.9600 |
C5—C6 | 1.371 (4) | C15—H15B | 0.9600 |
C5—H5 | 0.9300 | C15—H15C | 0.9600 |
O1—Pd1—O1i | 180.00 (10) | N1—C7—H7B | 108.9 |
O1—Pd1—N1i | 91.52 (8) | C6—C7—H7B | 108.9 |
O1i—Pd1—N1i | 88.48 (8) | H7A—C7—H7B | 107.7 |
O1—Pd1—N1 | 88.48 (8) | N1—C8—C9 | 122.4 (2) |
O1i—Pd1—N1 | 91.52 (8) | N1—C8—C15 | 120.7 (3) |
N1i—Pd1—N1 | 180.000 (1) | C9—C8—C15 | 116.9 (2) |
C10—O1—Pd1 | 118.68 (16) | C14—C9—C10 | 118.1 (3) |
C8—N1—C7 | 120.0 (2) | C14—C9—C8 | 119.6 (3) |
C8—N1—Pd1 | 124.82 (18) | C10—C9—C8 | 122.2 (2) |
C7—N1—Pd1 | 115.13 (17) | O1—C10—C11 | 117.9 (3) |
C2—C1—C6 | 120.9 (4) | O1—C10—C9 | 124.0 (2) |
C2—C1—H1A | 119.6 | C11—C10—C9 | 118.1 (3) |
C6—C1—H1A | 119.6 | C12—C11—C10 | 121.8 (3) |
C3—C2—C1 | 118.9 (4) | C12—C11—H11A | 119.1 |
C3—C2—H2A | 120.6 | C10—C11—H11A | 119.1 |
C1—C2—H2A | 120.6 | C11—C12—C13 | 120.3 (3) |
C4—C3—C2 | 122.6 (3) | C11—C12—H12A | 119.9 |
C4—C3—F1 | 118.5 (4) | C13—C12—H12A | 119.9 |
C2—C3—F1 | 118.9 (3) | C14—C13—C12 | 119.3 (3) |
C3—C4—C5 | 117.8 (3) | C14—C13—H13A | 120.3 |
C3—C4—H4A | 121.1 | C12—C13—H13A | 120.3 |
C5—C4—H4A | 121.1 | C13—C14—C9 | 122.4 (3) |
C6—C5—C4 | 121.9 (3) | C13—C14—H14A | 118.8 |
C6—C5—H5 | 119.0 | C9—C14—H14A | 118.8 |
C4—C5—H5 | 119.0 | C8—C15—H15A | 109.5 |
C5—C6—C1 | 117.9 (3) | C8—C15—H15B | 109.5 |
C5—C6—C7 | 123.5 (2) | H15A—C15—H15B | 109.5 |
C1—C6—C7 | 118.6 (3) | C8—C15—H15C | 109.5 |
N1—C7—C6 | 113.4 (2) | H15A—C15—H15C | 109.5 |
N1—C7—H7A | 108.9 | H15B—C15—H15C | 109.5 |
C6—C7—H7A | 108.9 | ||
N1i—Pd1—O1—C10 | −134.7 (2) | Pd1—N1—C8—C9 | −3.2 (4) |
N1—Pd1—O1—C10 | 45.3 (2) | C7—N1—C8—C15 | 0.2 (4) |
O1—Pd1—N1—C8 | −25.1 (2) | Pd1—N1—C8—C15 | 176.5 (2) |
O1i—Pd1—N1—C8 | 154.9 (2) | N1—C8—C9—C14 | −157.8 (3) |
O1—Pd1—N1—C7 | 151.39 (18) | C15—C8—C9—C14 | 22.6 (4) |
O1i—Pd1—N1—C7 | −28.61 (18) | N1—C8—C9—C10 | 24.0 (4) |
C6—C1—C2—C3 | −0.8 (9) | C15—C8—C9—C10 | −155.6 (3) |
C1—C2—C3—C4 | 2.6 (9) | Pd1—O1—C10—C11 | 141.1 (2) |
C1—C2—C3—F1 | −179.5 (5) | Pd1—O1—C10—C9 | −40.7 (3) |
C2—C3—C4—C5 | −2.3 (7) | C14—C9—C10—O1 | −178.0 (3) |
F1—C3—C4—C5 | 179.8 (3) | C8—C9—C10—O1 | 0.2 (4) |
C3—C4—C5—C6 | 0.2 (5) | C14—C9—C10—C11 | 0.2 (4) |
C4—C5—C6—C1 | 1.4 (5) | C8—C9—C10—C11 | 178.4 (3) |
C4—C5—C6—C7 | 179.4 (3) | O1—C10—C11—C12 | 178.2 (3) |
C2—C1—C6—C5 | −1.1 (7) | C9—C10—C11—C12 | −0.2 (5) |
C2—C1—C6—C7 | −179.1 (5) | C10—C11—C12—C13 | 0.4 (5) |
C8—N1—C7—C6 | 87.6 (3) | C11—C12—C13—C14 | −0.7 (5) |
Pd1—N1—C7—C6 | −89.0 (2) | C12—C13—C14—C9 | 0.8 (5) |
C5—C6—C7—N1 | 8.3 (4) | C10—C9—C14—C13 | −0.6 (4) |
C1—C6—C7—N1 | −173.7 (3) | C8—C9—C14—C13 | −178.8 (3) |
C7—N1—C8—C9 | −179.5 (2) |
Symmetry code: (i) −x+1, −y+2, −z+2. |
D—H···A | D—H | H···A | D···A | D—H···A |
C4—H4A···O1ii | 0.93 | 2.50 | 3.405 (5) | 165 |
Symmetry code: (ii) −x+2, −y+2, −z+2. |
Footnotes
‡Additional correspondence author, email: suchada.c@psu.ac.th. Thomson Reuters ResearcherID: A-5085-2009.
Acknowledgements
The authors wish to express their appreciation to the Universiti Teknologi MARA for the research grants Nos. 600-RMI/DANA 5/3/CIFI (1/2014) and 600-RMI/DANA 5/3/PSI (1/2014) and the research facilities. A scholarship from the Universiti Teknologi MARA and the Ministry of Education Malaysia is also gratefully acknowledged.
References
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