Dinuclear five-coordinate copper(II) complexes with chelating diphosphonic acid ligands: Hydrothermal synthesis, structure, and thermal properties

Article abstract of DOI:10.1002/zaac.201100495

The synthesis of two new diphosphonic acid ligands,[ethane-1, 2-diylbis(azanediyl)]bis[(4-chlorophenyl)methylene]diphosphonic acid (L ₁P), [ethane-1, 2-diylbis(azanediyl)]bis[(4-bromophenyl)methylene] diphosphonic acid (L₂P), and the

Full text of DOI:10.1002/zaac.201100495

ARTICLE
DOI: 10.1002/zaac.201100495
Dinuclear Five-Coordinate Copper(II) Complexes with Chelating
Diphosphonic Acid Ligands: Hydrothermal Synthesis, Structure, and
Thermal Properties
Saeed Dehghanpour,*[a] Saeedeh Asadizadeh,[a] and Jalil Assoud[b]
Keywords: Diphosphonic acids; Hydrothermal synthesis; X-ray diffraction; Thermal properties; Copper
Abstract. The synthesis of two new diphosphonic acid ligands,
copper(II) ions with a distorted square pyramidal arrangement doubly
[ethane-1,2-diylbis(azanediyl)]bis[(4-chlorophenyl)methylene]di- bridged by OPO from phosphonate groups. The Cu–Cu distance is
phosphonic acid (L1P), [ethane-1,2-diylbis(azanediyl)]bis[(4-bromo- 4.7810(2) Å. The crystal packing is determined by interdinuclear hy-
phenyl)methylene]diphosphonic acid (L2P), and their corresponding
drogen bonds, which lead to one-dimensional chains. The results of
copper complexes, Cu2(L1P)2 (1) and Cu2(L2P)2 (2) are described thermogravimetric investigations (TG-DTA), UV/Vis diffuse reflec-
herein. Complex 2 was structurally characterized with X-ray single tance, infrared and (1H and 13C) NMR spectroscopy, as well as elemen-
crystal diffraction. The structure of 2 consists of five-coordinate tal analyses of compounds 1 and 2 are also presented.
reported the structures of the complexes [NH3CH(CH3)-
Introduction
CH2NH3]2M2[O3PCH(Ph)NH(CH2)2NHCH(Ph)PO3]2·H2O,
(M = ZnII and CdII) and Zn2[O3PCH(Ph)NH(CH2)2NHCH-
(Ph)PO3]2(HNO3)2·4H2O.[15,16]
There has been a growing interest in the synthesis and char-
acterization of metal phosphonates due to their potential appli-
cations as catalysts, single molecular magnets, sorbents, ion
exchangers, protonic conductors, and scale inhibitors.[1–5] In
general, metal phosphonates are also reported to form discrete
coordination complexes, one-dimensional (1D) chain struc-
tures, two-dimensional (2D) layered and three-dimensional
(3D) structures.[6–9] One remarkable feature of these com-
pounds is that they are capable to form numerous hydrogen
bonds, which often contribute to the understanding of the asso-
ciated chemistry and mechanism of metal-assisted phosphate
ester hydrolysis.[9–11] Much effort has focused on the rational
design and controlled synthesis of coordination complexes
using phosphonate ligands and factors such as the performance
of organic ligand, the metal ion, and the reaction conditions
influence the molecular structure and modify properties of
metal phosphonates, which are important in practical applica-
tions.
In this work, we present the synthesis, spectral, and elemen-
tal analysis of two new diphosphonic acid ligands, [ethane-1,2-
diylbis(azanediyl)]bis[(4-chlorophenyl)methylene]diphos-
phonic acid (L1P), [ethane-1,2-diylbis(azanediyl)]bis[(4-bro-
mophenyl)methylene]diphosphonic acid (L2P) and their corre-
sponding dinuclear copper(II) complexes, Cu2(L1P)2 (1) and
Cu2(L2P)2 (2). These complexes were obtained by hydrother-
mal reactions between the phosphonate ligands (LXP) with
CuSO4 in aqueous media by modifying reaction parameters
such as the pH, temperature of the reaction mixture, and molar
ratio of the starting materials (LXP/Cu2+). Complexes 1 and
2 were characterized by thermogravimetric (TG-DTA), CHN,
Energy Dispersive X-ray (EDX) analyses, and UV/Vis diffuse
reflectance, IR, and (1H and 13C) NMR spectroscopy. The
structure of 2 was determined by X-ray single crystal diffrac-
tion. The spectral properties of these compounds are also dis-
cussed.
A variety of (O3P-tether-PO3) ligands and numerous metal
diphosphonate complexes of type [Mn(O3P-tether-PO3)m] were
describedinrecentyears.[12–14]Although[O3PCH(R)NH(CH2)2-
NHCH(R)PO3] type ligands also seem to be good candidates
for such studies, according to our search, only a few
complexes were reported. Fan and co-workers have
Results and Discussion
The formation of diphosphonic acid ligands takes place in
two steps (Scheme 1). The first step in this process involves
the formation of a diimine ligand (Lx) by the reaction of ethyl-
enediamine with benzaldehyde derivatives. In the second step,
trimethyl phosphite reacts with diimine ligand to afford the
diphosphonic acid ligand (LXP). The ligands were insoluble in
water and common organic solvents such as MeOH, EtOH,
MeCN, THF, DMSO, and DMF, but soluble in aqueous alkali
solution.
* Dr. S. Dehghanpour
E-Mail: Dehganpour_farasha@yahoo.com
[a] Department of Chemistry
Alzahra University
P.O.Box 1993891176
Tehran, Iran
[b] Department of Chemistry
University of Waterloo
Waterloo, Ontario, Canada N2L 3G1
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S. Dehghanpour, S. Asadizadeh, J. Assoud
ARTICLE
1
The assignments for the H NMR spectra of the ligands are
presented in the Experimental Section. The signals are as-
signed based on the splitting of the resonance signals, spin
coupling constants and literature data. The 1H NMR spectra of
L1P and L2P show a multiplet signals for the –NCH(Ph)– pro-
tons. Furthermore, the 13C NMR spectra of these ligands show
two doublet signals for the –N13CH(Ph)– carbon atoms. In the
presence of two chiral carbon atoms in the ligands, it seems
that diastereomers are present in solution. This is in accordance
with the molecular structure determined by the X-ray crystal
structure analysis for complex 2 (dimeric molecule have two
ligands with different chairalities for NCH(Ph)– carbon atoms
of each ligand)
Scheme 1.
In this study, two new copper complexes 1 and 2 were ob-
tained by hydrothermal reaction between the ligand (LXP) and
CuSO4 in an aqueous solution. Factors, which have a profound
impact in the product formation in hydrothermal syntheses are
concentration, pH, temperature of the reaction mixture, and
molar ratio of starting materials (LXP/Cu2+).[17] Therefore, sev-
eral individual hydrothermal reactions were performed under
various conditions of CuSO4 to LXP molar ratio, temperature
(T = 120 to 170 °C in steps of 20 °C, t = 3 d), and pH 5–8 for
the synthesis of the complexes 1 and 2. A comparison between
the EDX analyses, XRD pattern, IR spectra, and elemental
analyses of products of the above individual experiments indi-
cates that products are identical.
Cu2(L1P)2 (1) is only formed at 150 °C. The compound is
formed over a wide range of molar ratios of L1P/Cu2+ = 1:1,
1:1.5, 1:2, 1:4 and 2:1, which approximately correlates with pH
6–8. Cu2(L2P)2 (2) is mainly formed at temperatures from 150
to 170 °C in approximately the same field of formation (L2P/
Cu2+ = 1:1, 1:1.5, 1:2, and 2:1) as compound 1 (pH 6–7).
Compounds 1 and 2 were obtained as microcrystalline prod-
ucts under above mentioned conditions. Thus, the reaction
mixtures were diluted by addition of water for growth of
microcrystalline products having larger crystallite size, which
makes them suitable for single-crystal X-ray diffraction. This
approach led to the formation of single crystal of complex 2.
However, 1 was only isolated as a microcrystalline compound.
Therefore, the composition of 1 was determined based on ther-
mogravimetric (TG-DTA), CHN, Energy Dispersive X-ray
(EDX), and X-ray diffraction analyses (Figure 1) as well as
UV/Vis diffuse reflectance and IR spectroscopy.
The synthesized compounds were studied by IR spec-
troscopy. The broad band at 3251 cm–1 for L1P or 3260 cm–1
for L2P can be attributed to the P–OH stretching vibration of
the ligands. The corresponding deformation band appears at
1627 cm–1 for L1P and 1615 cm–1 for L2P.[18–20] The bands at
3063 cm–1 for L1P and 3078 cm–1 for L2P can be assigned to
the N–H stretching vibration. The corresponding N–H defor-
mation vibrations of L1P and L2P appear at 1342 and 1369 cm–1,
respectively.[16] Bands corresponding to aromatic and aliphatic
C–H stretching vibrations of the L1P and L2P are observed
between 3017 and 2921 cm–1. The P=O stretching vibration of
the phosphonate group in L1P and L2P appears as strong band
around 1200 cm–1, whereas the bands between 833–1188 cm–
1
are assigned to stretching vibrations of the tetrahedral CPO3
groups and to C–C vibrations.
The bands at 3235 cm–1 for 1 and 3242 cm–1 for 2, respec-
tively, can be assigned to the P–OH stretching vibrations of
the complexes. The bands at 3063 cm–1 for 1 and 3045 cm–1
for 2, respectively, are due to the N–H stretching vibration.
The corresponding N–H deformation vibrations of compounds
1 and 2 appear at 1348 and 1352 cm–1, respectively. The weak
bands around 2926 to 3024 cm–1 are probably due to the vi-
bration of aromatic and aliphatic C–H bonds. Bands at 1165
and 1153 cm–1 are due to P=O stretching vibrations of com-
pounds 1 and 2, respectively. Compounds 1 and 2 exhibit typi-
cal bands in the range 816–1090 cm–1, which are due to the
stretching vibrations of the –CPO3 group and to C–C vi-
brations.[17]
The diffuse reflectance UV/Vis spectra of 1 and 2 show a
broad absorption band in the visible region at 648 and 659 nm,
which is assigned to a dxy, dyz Ǟ dx2–y2 transition.[21–23] This
spectral feature clearly reveals the presence of five-coordinate
arrangement around the central Cu2+ ion and is more consistent
with square pyramidal or distorted square pyramidal (SP) ar-
rangement.[24,25] The absorption spectra of the complexes have
absorption bands in the 200–300 nm range (see Experimental
Section) attributed to ligand-centered πǞπ* and/or charge
transfer transitions.[20,26]
The perspective view of the dimeric copper(II) complex,
Cu2(L1P)2 indicating atom-numbering scheme with thermal el-
lipsoids at 50% probability is illustrated in Figure 2. The crys-
tallographic data for compound 2 is summarized in Table 1.
Selected bond lengths, bond angles, and torsion angles are
listed in Table 2.
Figure 1. XRD pattern of Cu2(L1P)2 (1).
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Copper(II) Complexes with Chelating Diphosphonic Acid Ligands
Table 1. Crystal data and single-crystal X-ray diffraction refinement
details for compound 2.
Formula
C32H36Br4Cu2N4O12P4
Formula weight
Temperature /K
1239.25
200
Wavelength /Å
Crystal system
Space group
0.71073
triclinic
P1
¯
a /Å
8.8467(13)
b /Å
12.9976(19)
c /Å
19.433(3)
α /°
73.074(3)
β /°
85.701(3)
γ /°
83.489(3)
2121.9 (5)
V /A3
Z
2
Density /g·cm–3
1.940
4.98
μ /mm–1
F(000)
1220
Crystal size
Theta range for data collection
0.36ϫ0.08ϫ0.08
2.97 to 30.0
–12 Յ h Յ 12, –18 Յ k Յ 18,
–27 Յ l Յ 27
32745
Index ranges
Reflections collected
Independent reflections
Completeness to θ = 30.0°
Absorption correction
12327 [R(int) = 0.0367]
99.5%
Empirical
Max. and min. transmission
Refinement method
0.8256 and 0.2671
Full-matrix least-squares on F2
12327 / 0 / 523
1.139
Data / restraints / parameters
Goodness-of-fit on F2
Final R indices [I Ͼ 2σ(I)]
R indices (all data)
R1 = 0.0402, wR2 = 0.0781
R1 = 0.0662, wR2 = 0.0849
1.263 and –0.946
Largest diff. peak and hole /e·Å–3
Figure 2. Crystal structure of Cu2(L2P)2 (2) (a) Conformer A (the
atom-labeling scheme is shown for clarity), (b) Conformer B (hydro-
gen atoms are omitted for clarity).
bond length is 2.3620(19) Å in A and 2.3733(19) Å in B,
which links the complex molecules to a dimeric structure, re-
The asymmetric unit of the complex consists of two inde- sulting in a Cu–Cu distance of 4.98010(9) Å in A and
pendent molecules (A and B).
5.0068(9) Å in B. This distance is near the range of reported
Though the coordination arrangement of copper(II) is very values of ca. 5 Å observed for polyatomic bridges.[16,30] The
similar in both structures, there are small differences in bond bond lengths of Cu–O1 and Cu–O5 are 1.9392(18) and
lengths and bond angles.
1.9715(19) Å in A and 1.9401(18) and 1.9718(19) Å in B,
It is interesting that the molecules are centrosymmetric and respectively, which are similar to the Cu–O bond length of
have a dimeric structure, where two copper ions are doubly other five coordinated copper(II) complexes.[27] The average
bridged by OPO groups forming an eight-membered dinuclear Cu–Namine bond length is 2.015 Å. The axial oxygen–metal–
ring. The arrangement of the chair like, eight membered ring ligand angles differ from the ideal values for a square pyramid
(Figure 3) (Cu–O1–P1–O6–Cui–O1i–P1i–O6i) is very similar varying from 80.98(8)° (N2A–Cu1A–O6A) to 107.52(9)°
to that of the previously reported metal diphosphonate com- (N1A–Cu1A–O6A) in A and 80.66(8)° (N2B–Cu1B–O6B) to
pounds.[16,27–28] Each copper atom in the dinuclear complex 106.63(8)° (N1B–Cu1B–O6B) in B. Likewise, the basal li-
displays a five-coordinate distorted square-pyramidal coordi- gand–metal–ligand angles vary between 85.37(9)° (N1A–
nation, though there is appreciable distortion towards trigonal Cu1A–N2A) and 97.66(8)° (O1A–Cu1A–O5A) in A and
bipyramid with trigonality index, τ = 0.22 for A and 0.21 for 85.65(9)° (N1B–Cu1B–N2B) and 97.72(8)° (O1B–Cu1B–
B [τ is the parameter describing the degree of trigonal distor- O5B) in B. Such distortion could be due to the restriction in-
tion and is defined as τ = (θ1–θ2)/60, where θ1 and θ2 are duced by the fused chelate ring.
two largest ligand–metal–ligand angles, τ = 0 for ideal square-
Each ligand (L2P) acts as pentadentate ligand, chelating to
pyramid (SP) and τ = 1 for ideal trigonal bipyramid (TBP)].[29] the one CuII ion through its amine nitrogen atoms N1 and N2,
The equatorial plane formed by oxygen and nitrogen atoms oxygen O1 and O5 from the P–O group and bridges another
(for example O1, O5, N2, and N1), whereas one phosphonate CuII ion by phosphoryl oxygen O6 from the P=O group form-
oxygen atom (O6i) from the neighboring ligand (L2P) is the ing six five-membered rings and one eight-membered ring.
apex occupying the fifth site. The distance from copper atom The dihedral angle between the planes constituted by the che-
to the least square plane formed by O1, O2, N2, and N1 is late rings Cu1O1P1C1N1 and Cu1O5P2C10N2 is 4.04(8)° in
0.1420(4) Å in A and 0.1275(4) Å in B. The axial Cu–O6i A and 4.32(7)° in B, whereas the dihedral angle between the
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863

S. Dehghanpour, S. Asadizadeh, J. Assoud
ARTICLE
Table 2. Selected bond lengths /Å and angles /° for two independent molecules of compound 2.
Molecule A
Molecule B
Bond lengths
Cu1A–O1A
Cu1A–O5A
Cu1A–N1A
Cu1A–N2A
1.9392(18)
1.9715(19)
2.008(2)
2.018(2)
2.3620(19)
Cu1B–O1B
Cu1B–O5B
Cu1B–N1B
Cu1B–N2B
Cu1B–O6B
1.9401(18)
1.9718(19)
2.013(2)
2.021(2)
2.3733(19)
Cu1A–O6A
Bond angles
O1A–Cu1A–O5A
O1A–Cu1A–N1A
O5A-Cu1A-N2A
N1A–Cu1A–N2A
O1A–Cu1A–O6A
O5A–Cu1A–O6A
N1A–Cu1A–O6A
N2A–Cu1A–O6A
O5A–Cu1A–N1A
O1A–Cu1A–N2A
97.66(8)
88.58(8)
90.21(8)
85.37(9)
95.07(7)
93.04(7)
107.52(9)
80.98(8)
157.95(9)
171.40(9)
O1B–Cu1B–O5B
O1B–Cu1B–N1B
O5B–Cu1B–N2B
N1B–Cu1B–N2B
O1B–Cu1B–O6B
O5B–Cu1B–O6B
N1B–Cu1B–O6B
N2B–Cu1B–O6B
O5B–Cu1B–N1B
O1B–Cu1B–N2B
97.72(8)
88.51(8)
90.17(8)
85.65(9)
94.54(7)
93.44(7)
106.63(8)
80.66(8)
158.50(9)
171.02(9)
Figure 3. Chair conformation of the eight-membered chelate ring.
chelate plane Cu1O1P1C1N1 and the adjacent chelate ring
CuN1C8C9N2 is 7.60(6)° in A and 5.97(7)° in B. This shows
that the tetradentate chelating ligand is puckered, while coordi-
nating to copper(II). Two {CPO3} moieties coordinate with
copper atoms by two different modes, one of them acting as a
monodentate mode and the other adopting a bidentate fashion.
The coordination environment around phosphorus atoms of
each L is approximately tetrahedral since the average of six
angles involving phosphorus are 109.45° and 109.40° (A and
B) for P(1) and P(2), respectively.
The structure of each independent molecule in the complex
is stabilized by an extensive system of intermolecular hydro-
gen bonds and the one-dimensional chains are formed along a
axis (Figure 4). The phosphoryl oxygen atom (O3) excluded
from complexation acts as an acceptor for the formation of
intermolecular hydrogen bond type interactions with the hy-
drogen atoms H(2A) and H(1X) of the neighboring complex.
Furthermore, hydrogen atoms H(2A) and H(1X) take part in
the same hydrogen bonding to the phosphoryl oxygen atoms
of the neighboring complex molecules (Table 3). On the other
hand, there are strong intramolecular hydrogen bonds in the
molecule, in which hydroxyl groups of phosphonate unit act
as hydrogen donors, whereas bridged oxygen atoms from adja-
cent phosphonate group act as acceptors. The short O–O dis-
tances (2.676 Å) indicate very strong mutual electrostatic inter-
actions.
Figure 4. N–H···O and O–H···O hydrogen bonds are forming chains
of Cu2(L2P)2 (2) molecules along a axis.
The thermal properties of the copper(II) complexes were
studied in the range 25–800 °C. It reveals that they do not
contain adsorbed or coordinated water or solvent molecules,
which is in agreement with the analytical and spectroscopic
data. The complexes are stable in air at room temperature.
The mass loss of complex 1 starts at 265 °C. DTA shows a
strong exotherm centered at 305 °C with an associated weight
loss of 28% (Figure 5). A second broad exothermic effect is
observed in the temperature range of 400–610 °C correspond-
ing to a weight loss of 42%. These weight losses are in agree-
ment with the loss of the organic components to yield Cu2P2O7
(weight loss observed 70%, weight loss calcd. 72%). As
shown in Figure 6, the weight loss of complex 2 starts at
260 °C. The thermal analysis of 2 shows also two steps in
the decomposition. DTA shows a strong exotherm centered at
295 °C followed by a broad exotherm in the temperature range
of 390–600 °C accompanied by two weight losses of 33 and
42%. The final product is Cu2P2O7 (weight loss observed
75%, weight loss calcd. 76%). The similarities in the TG/DTA
curves of 1 and 2, suggest closely related structures.
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Copper(II) Complexes with Chelating Diphosphonic Acid Ligands
Table 3. Hydrogen bonds D–H···A for two independent molecules of compound 2.
Molecule
D–H···A
A
d(D-H)
d(H···A)
d(D···A)
Ͻ(DHA)
A
N1A–H1AX···O3A
O2A–H2AA···O3A
O4A–H4AA···O6A
N1B–H1BX···O3B
O2B–H2BA···O3B
O4B–H4BA···O6B
[–x+1, –y, –z+1]
[–x+2, –y, –z+1]
[x, y, z]
[–x+2, –y+1, –z]
[–x+3, –y+1, –z]
[x, y, z]
0.93
0.84
0.84
0.93
0.84
0.84
2.062
1.787
1.85
2.079
1.781
1.848
2.893
2.621
2.676
2.903
2.615
2.677
147.96
171.38
167.34
146.85
171.43
168.55
B
copper(II) ions doubly bridged by OPO from phosphonate. The
structure of each independent molecule in the complex is stabi-
lized by an extensive system of intermolecular hydrogen bonds
and the one-dimensional chains are formed along the a axis.
The diffuse reflectance UV/Vis spectra of 1 and 2 show a
broad absorption band in the visible region at 648 and 659 nm,
which is in agreement with a distorted square pyramidal ar-
rangement. The complexes are stable up to a temperature of
about 260 °C
Experimental Section
General: All reagents were analytical grade commercial products and
were used without further purification. Elemental analyses were per-
formed with a Heraeus CHN-ORAPID elemental analyzer. Infrared
spectra were recorded with a Bruker Tensor 27 spectrophotometer.
NMR spectra were obtained with a Bruker Avance DRX 250
(250 MHz) spectrometer. Proton chemical shifts are reported in part
per million (ppm) relative to an internal standard of Me4Si. UV/Vis
spectra were obtained with a Shimadzu UV-260 spectrophotometer.
The compositional analyses were done by energy dispersive X-ray
(EDX, Kevex, Delta ClassI). Thermogravimetric analysis was carried
out with a Perkin–Elmer Pyris thermal analysis system with a heating
rate of 10 K·min–1.
Figure 5. TGA-DTA curves for Cu2(L1P)2 (1).
Syntheses
N,NЈ-Bis(4-chlorobenzylidene)ethane-1,2-diamine (L1): To a solu-
tion of 4-chlorobenzaldehyde (4 g, 28 mmol) in diethyl ether (30 mL)
was added a solution of ethylenediamine (0.84 g, 14 mmol) in diethyl
ether (20 mL) and the resulting mixture was stirred for 45 min at room
temperature. Afterwards, the solution was filtered, volatiles removed
and the remaining white solid was washed with diethyl ether and dried
˚
in vacuo. Yield 90%; m.p.: 140C. Anal. for C16H14Cl2N2(305.21):
calcd. C 62.97; H 4.62; N 9.18%; found: C 62.01; H 4.65; N 9.17%.
IR (KBr): ν˜ = 1643 (C=N), 1484 (C=C), 817 (= CH) cm–1.
Figure 6. TGA-DTA curves for Cu2(L2P)2 (2).
N,NЈ-Bis(4-bromobenzylidene)ethane-1,2-diamine (L2): This com-
pound was prepared by a procedure similar to that for the synthesis of
N,NЈ-bis(4-chlorobenzylidene)ethane-1,2-diamine (L1) using 4-bro-
mobenzaldehyde (4 g, 22 mmol) to form N,NЈ-Bis(4-bromobenzyl-
Conclusions
˚
idene)ethane-1,2-diamine as a white solid. Yield 90%; m.p.: 148C.
Two new diphosphonic acid ligands, [ethane-1,2-diylbis(az-
Anal. for C16H14Br2N2 (394.11): calcd. C 48.76; H 3.58; N 7.11%;
found: C 48.74; H 3.59; N 7.11%. IR (KBr): ν˜ = 1641 (C=N), 1479
(C=C), 816 (= CH) cm–1.
anediyl)]bis[(4-chlorophenyl)methylene]diphosphonic
(L1P), [ethane-1,2-diylbis(azanediyl)]bis[(4-bromophenyl)
acid
methylene]diphosphonic acid (L2P) and their corresponding
two copper complexes Cu2(L1P)2 (1) and Cu2(L2P)2 (2) were
synthesized and characterized by elemental analysis, UV/Vis
diffuse reflectance, infrared, and (1H and 13C) NMR spec-
troscopy. Additionally, the solid-state structure of 2 consists
[Ethane-1,2-diylbis(azanediyl)]bis[(4-chlorophenyl)
methylene]diphosphonic Acid (L1P): The ligand [ethane-1,2-diylbis-
(azanediyl)]bis[(4-chlorophenyl)methylene]diphosphonic acid was
prepared according to reported procedures.[16] A mixture of trimethyl
of five-coordinate in distorted square pyramidal arrangement phosphite (1.66 g, 10 mmol) and L1 (1.52 g, 5 mmol) was dissolved in
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S. Dehghanpour, S. Asadizadeh, J. Assoud
ARTICLE
glacial acetic acid (20 mL). This mixture was stirred at 80–85 °C for
3 h. Afterwards the solvent was removed by evaporation using rotary
evaporator to give viscous yellow oil. HCl (12 m, 15 mL) was added
to the above oil and the mixture was heated to reflux for about 3 h.
Excess HCl was removed at reduced pressure and distilled water
(5.4 mL) was added. The resulting solution was heated to reflux for 1
h to give a white solid. The compound was purified using distilled
water and acetone solution to yield 65% white powder solid, m.p.
242 °C. C16H20Cl2N2O6P2 (469.20): calcd. C 40.96; H 4.30; N 5.97%;
found C 40.99; H 4.33; N 5.95%. IR (KBr): ν˜ = 3251 m, 3063 m,
2929 w, 2975 w, 3017 w, 1627 s, 1495 s, 1415 w, 1342 m, 1210 s,
1162 s, 1083 s, 1012 s, 930 s, 853 s, 770 w, 711 m, 677 m, 630 m,
fined with full-matrix least-squares procedures (SHELXTL-97)[33]
with anisotropic thermal parameters for all non-hydrogen atoms.
Crystallographic data (excluding structure factors) for the structure
in this paper have been deposited with the Cambridge Crystallo-
graphic Data Centre, CCDC, 12 Union Road, Cambridge CB21EZ,
UK. Copies of the data can be obtained free of charge on quoting the
depository number CCDC-853051 (Fax: +44-1223-336-033; E-Mail:
deposit@ccdc.cam.ac.uk, http://www.ccdc.cam.ac.uk).
Acknowledgement
1
556 m, 508 m, 446 m cm–1. H NMR (NaOD+D2O): δ = 2.34 (s, 4
Financial support by the Alzahra University is gratefully acknowl-
edged.
H, NCH2CH2N), 3.42 [m, 2 H, 2(–NCHPh–)], 7.04–7.14 (m, 8 H,
2ArH). 13C NMR (NaOD+D2O): δ = 46.1(–N13CH213CH2N–), 61.9
(d, 1Jp–c = 6.5 Hz), 63.6 d, 1Jp–c = 5.5 Hz), 127.9, 128.19, 130.0, 131.6,
137.9, 137.9. 31P NMR (NaOD+D2O): δ = 15.35, 15.44.
References
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Received: November 12, 2011
Published Online: March 8, 2012
Z. Anorg. Allg. Chem. 2012, 861–867
© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.zaac.wiley-vch.de
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