Synthesis of a new carbbenzyloxymethylenetriphenylphosphorane ylide and the study of its reaction with mercury(II) halides: Spectral and structural characterization

Article abstract of DOI:10.1016/j.poly.2008.03.010

The reaction of the title ylide, Ph₃P{double bond, long}CHCOOCH₂Ph (BAPPY), with mercury(II) halides in equimolar ratios using methanol as a solvent produces the mercurated complexes [(BAPPY) · HgCl₂]₂ (1), [(BAPPY) · HgBr₂]₂ (2) and [(BAPPY) · HgI₂]₂ (3) in good yields. Single crystal X-ray analysis of 3 reveals the presence of a centrosymmetric dimeric structure containing the ylide and HgI₂. The IR, ¹H, ¹³C and ³¹P NMR data for the latter compound are similar to those of 1 and 2, indicating similar structures. Elemental analysis indicate a 1:1 stoichiometry between the ylide and Hg(II) halide in each of the three products.

Full text of DOI:10.1016/j.poly.2008.03.010

Polyhedron 27 (2008) 1963–1968
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Polyhedron
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Synthesis of a new carbbenzyloxymethylenetriphenylphosphorane ylide
and the study of its reaction with mercury(II) halides: Spectral and
structural characterization
b
a
a
Seyyed Javad Sabounchei a, , Alireza Dadrass , Fateme Akhlaghi , Zabiholla Bolboli Nojini ,
*
Hamid Reza Khavasi c
a Faculty of Chemistry, Bu-Ali Sina University, Hamedan 65174, Iran
b Chemistry Department, Urmia University, Urmia 57159-165, Iran
c Department of Chemistry, Shahid Beheshti University, Evin, Tehran 1983963113, Iran
a r t i c l e i n f o
a b s t r a c t
Article history:
The reaction of the title ylide, Ph3P@CHCOOCH2Ph (BAPPY), with mercury(II) halides in equimolar ratios
Received 1 December 2007
Accepted 4 March 2008
Available online 21 April 2008
using methanol as
a
solvent produces the mercurated complexes [(BAPPY) ꢀ HgCl2]2 (1), [(BAP-
PY) ꢀ HgBr2]2 (2) and [(BAPPY) ꢀ HgI2]2 (3) in good yields. Single crystal X-ray analysis of 3 reveals the
presence of a centrosymmetric dimeric structure containing the ylide and HgI2. The IR, 1H, 13C and 31P
NMR data for the latter compound are similar to those of 1 and 2, indicating similar structures. Elemental
analysis indicate a 1:1 stoichiometry between the ylide and Hg(II) halide in each of the three products.
Ó 2008 Elsevier Ltd. All rights reserved.
Keywords:
a-Stabilized phosphorus ylide
Mercury(II) halide complexes
Triphenylphosphine
1. Introduction
[10] [APPY = Ph3CCOMe; L2 = PPh3, PBu3, bipy] contain stable ylides
O-linked to a soft metal center. Other attempts to obtain this kind
Carbonyl-stabilized phosphorus ylides are very versatile ligands
for three reasons: (i) they have two alternate modes of coordina-
tion, A [1] and B [2] (Scheme 1); (ii) they give stable complexes
in spite of their low nucleophilicity (arising from electron delocal-
ization through resonance forms a–c (Scheme 1)); and (iii) they al-
low the synthesis of unusual types of complexes [3].
The preparation and characterization of a-stabilized phospho-
rus ylides, and metal complexes incorporating in this type of ylides,
has attracted much attention in recent years. This interest has been
driven primarily by the necessity to develop new reagents for
chemical synthesis that exhibit enhanced properties [4]. It is the
requirement to satisfy this need that has provided the impetus
for our work, which has been directed towards evaluating the ligat-
ing behavior of phosphorus ylides. In the compounds reported to
date, the chemical behavior of the a-keto phosphorus ylides has
been clearly dominated by the C-coordinated form [5], and very
few examples of O-coordinated ylides are known [6].
of O-coordination to ‘‘classical” soft metals such as Pd(II), Pt(II) or
Hg(II) [7] invariably gave C-coordination.
Phosphorus ylides are known to demonstrate rich coordination
chemistry. One of the significance aspects of our work is to ascer-
tain the preferred coordination modes of BAPPY to the Hg metal. In
this study, we describe the preparation, spectroscopic character-
ization (IR and NMR) of mercury(II) complexes with the title ylide.
By a comparison of the data collected and single crystal X-ray dif-
fraction of 3, it demonstrates C-coordination of the ylide to the
metal.
2. Experimental
2.1. Materials
Methanol was distilled over magnesium powder and diethyl
ether (Et2O) was distilled over a mixture of sodium and benzophe-
none just before use. All other solvents were reagent grade and
used without further purification. Mercury halides, bromobenzy-
lacetate and triphenylphosphine were purchased from Merck.
Some of these examples contain the ylide O-coordinated to a
hard metal, which means there is a very oxophilic metal center,
such as Sn(IV) [6a] or a group with a high oxidation number
[6b]. Only W(0) complexes of the type W(CO)5L (L = ylide) [6c]
and Pd(II) complexes of the stoichiometry [Pd(C6H5)L2(APPY)]ClO4
2.2. Physical measurements
Melting points were measured on a SMPI apparatus. Elemental
analyses for C, H and N were performed using a Perkin–Elmer 2400
* Corresponding author.
E-mail address: Jsabounchei@yahoo.co.uk (S.J. Sabounchei).
0277-5387/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2008.03.010

1964
S.J. Sabounchei et al. / Polyhedron 27 (2008) 1963–1968
[M]
graphic software package [9]. The numerical absorption coefficient,
l, for Mo Ka radiation is 7.748 mmꢂ1. A numerical absorption cor-
rection was applied using X-RED [10] and X-SHAPE [11] software pack-
ages which resulted in transmission factors ranging from 0.212 and
0.083. The data were corrected for Lorentz and polarizing effects.
The structure was solved by direct methods [12]. All of the non-
hydrogen atoms were refined anisotropically. All of the hydrogen
atoms were located in ideal positions. Anomalous dispersion ef-
fects were included in Fcalc [13], the values for Df0 and Df00 were
those of Creagh and McAuley [14]. The values for the mass attenu-
ation coefficient are those of Creagh and Hubbell [15].
O
C
O
R
Ph3P
CH
C
Ph3P
R
CH
B
[M]
A
-
O
C
O
C
O
+
C
+
R
R
Ph3P
Ph3P
-
R
Ph3P
CH
CH
c
CH
a
b
2.5. Computational methods
Scheme 1.
The quantum chemical calculations were performed with
GAUSSIAN03 [16]. The geometries were fully optimized using DFT
at the B3LYP/LanL2MB level of theory [17]. This basis set includes
effective core potentials (ECP) for both the mercury and phospho-
rus as well as halide (Cl, Br, and I) ions. The stability energy values
for the complex and the energies of the highest occupied molecu-
lar orbital (HOMO) and lowest unoccupied molecular orbital
(LUMO) of complex were calculated. Moreover, the HOMO–LUMO
(H–L) energy gap, partial charges calculated from NBO analysis
(natural bond orbital), structural parameters (such as bond
lengths, bond angles), dipole and quadrupole moment were eval-
uated by DFT calculations. Atomic coordinates for the DFT calcula-
tions were obtained from the data of the X-ray crystal structure
analyses for 3.
series analyzer. Fourier transform IR spectra were recorded on a
Shimadzu 435-U-04 spectrophotometer and samples were pre-
pared as KBr pellets. 1H, 13C and 31P spectra were recorded on a
90 MHz Jeol spectrometer. X-ray analysis was performed on a STOE
IPDS-II diffractometer.
2.3. Synthesis of the ligand and the metal complexes
2.3.1. Synthesis of BAPPY
A solution of triphenylphosphine (0.52 g, 2 mmol) and bromob-
enzylacetate (0.42 g, 2 mmol) in dry chloroform (15 mL) was stir-
red at room temperature for 10 h. The resulting white precipitate
was filtered off, washed with diethyl ether and dried. Further
treatment with an aqueous solution of NaOH (0.5 M, 50 mL) led
to elimination of HBr, giving the free ligand. Yield: 0.66 g (89.3%),
m.p. 118–120 °C. Anal. Calc. for for C27H20O2P: C, 79.00; H, 5.64.
Found: C, 78.44; H, 5.43%.
3. Results and discussion
3.1. Synthesis
Reactions of HgX2 (X = Cl, Br and I) with ylides in a 1:1 stoichi-
ometry afforded halide-bridged dimeric structures 1–3 (Scheme 2)
containing C-coordinated ylide ligands.
2.3.2. Synthesis of [(BAPPY) ꢀ HgCl2]2 (1)
General procedure: To a magnetically stirred solution of HgCl2
(0.135 g, 0.5 mmol) in methanol (10 mL), was added a methanolic
solution (5 mL) of the ylide BAPPY (0.205 g 0.5 mmol). After 8 h the
solvent was removed under reduced pressure to 3 mL. After
addition of diethyl ether (30 mL) a white solid product was sepa-
rated by filtration. Yield: 0.28 g (82.7%), m.p. 173–176 °C. Anal.
Calc. for C54H40Cl4Hg2O4P2: C, 47.55; H, 3.39. Found: C, 46.26; H,
3.17%.
3.2. Infra-red spectra
The m(CO) band, which is sensitive to complexation, occurs at
1610 cmꢂ1 for the parent ylide, as in the case of other resonance
stabilized ylides [18]. Coordination of the ylide through carbon
causes an increase in m(CO), while for O-coordination a lowering
of m(CO) is expected (Table 1).
The infrared absorption bands observed for the three complexes
at 1707, 1702 and 1688 cmꢂ1 indicate coordination of the ylide
through carbon. The m(P+–Cꢂ) value, which is also diagnostic for
the coordination, occurs at 958 cmꢂ1 in Ph3P+–ꢂCH2 and at
887 cmꢂ1 in BAPPY. In the present study, the m (P+–Cꢂ) values for
all three complexes were shifted to lower frequencies and were
observed at 839, 831 and 827 cmꢂ1 for 1, 2 and 3, respectively,
suggesting some removal of electron density from the P–C bond
[19].
2.3.3. Synthesis of [(BAPPY) ꢀ HgBr2]2 (2)
Yield: 0.35 g (85.2%), m.p. 177–179 °C. Anal. Calc. for
C54H40Br4Hg2O4P2: C, 42.07; H, 3.00. C, 41.18; H, 2.83%.
2.3.4. Synthesis of [(BAPPY) ꢀ HgI2]2 (3)
Yield: 0.36 g (81.8%), m.p. 167–170 °C. Anal. Calc. for C54H40I4-
Hg2O4P2: C, 37.49; H, 2.67. C, 37.10; H, 2.55%.
2.4. X-ray crystallography
Crystals were obtained from a dichloromethane/diethyl ether
solution by solvent diffusion. A block colorless crystal of 3 having
approximate dimensions of 0.25 ꢁ 0.15 ꢁ 0.12 mm was mounted
on a glass fiber. All measurements were made on a STOE IPDS-II
diffractometer with graphite monochoromated Mo Ka radiation
(k = 0.7107 nm).
The data were collected at 298 K to a maximum h value of
26.78 ° and in a series of x scans in 1 ° oscillations with 60 s expo-
sures. Of the 33902 reflections that were collected, 11871 were
unique (Rint = 0.0442), equivalent reflections were merged. Data
were collected and integrated using the STOE X-AREA software pack-
age [8]. The refinement was performed using the X-STEP32 crystallo-
3.3. NMR spectral data
The 1H NMR data for the mercury(II) complexes, along with
those of the parent ylide, are listed in Table 2.
The signals due to the methine protons, when recorded in
CDCl3, were either broad or unobserved, probably due to the very
low solubility of all the complexes in CDCl3. Similar behavior was
observed earlier in the case of ylide complexes of mercury(II)
halides [20,21].
The expected downfield shifts of 31P and 1H signals for the PCH
group upon complexation were observed in their corresponding

S.J. Sabounchei et al. / Polyhedron 27 (2008) 1963–1968
1965
P+Ph3
X
CH3OH
rt
CH
PhH2CO
X
Ph3PCHCOOCH2Ph+ HgX2
O
Hg
Hg
O
X
X
CH
OCH2Ph
(1)
(2)
X= Cl
X= Br
P+Ph3
(3) X= I
Scheme 2.
Table 3
13C NMR data of BAPPY and its complexes with mercury (II) halides
Table 1
m(CO) of selected phosphoranes and their metal complexes
b
b
b
Possible
BAPPYa
BAPPY ꢀ HgCl2
BAPPY ꢀ HgBr2
BAPPY ꢀ HgI2
Compound
m(CO) cmꢂ1
Ref.
assignments
Ph3PCHCON(CH3)2
Ph3PCHCOCH3 (APPY)
Ph3PCHCOPh (BPPY)
(C6H4CH3)3PCHCOOCH2C6H5 (BAPPY)
1530
1530
1525
1610
[24]
[25]
[26]
CH
30.03 (d) br
br
–
br
–
1JPC
124.89
–
CH2
63.58 (s)
66.35 (s)
67.09 (s)
135.50 (s)
127.91 (s)
127.74 (s)
127.91 (s)
122.54 (d)
89.32
132.97 (d)
10.15
129.25 (d)
12.29
65.56 (s)
135.78 (s)
127.95 (s)
128.75 (s)
127.95 (s)
119.74 (d)
92.72
133.04 (d)
10.48
130.00 (d)
11.78
This work
(CH2Ph) (i)
(CH2Ph) (o)
(CH2Ph) (m)
(CH2Ph) (p)
PPh3 (i)
1JPC
138.32 (s) 135.50 (s)
127.68 (s) 127.97 (s)
127.36 (s) 127.79 (s)
126.66 (s) 127.97 (s)
125.93 (d) 121.84 (d)
C-coordination
BAPPY ꢀ HgCl2 (1)
BAPPY ꢀ HgBr2 (2)
BAPPY ꢀ HgI2 (3)
BPPY ꢀ HgCl2
1707
1702
1688
1635
1630
1605
This work
This work
This work
[12]
[12]
[24]
63.19
132.55 (d) 132.54 (d)
9.88 10.00
128.34 (d) 129.41 (d)
12.25 12.34
88.69
BPPY ꢀ HgBr2
PPh3 (o)
Au [CH(PPh3)CON(CH3)2]
2JPC
PPh3 (m)
3JPC
PPh3 (p)
CO
O-coordination
[(Sn(CH3)3 ꢀ BPPY]Cl
1480
1470
1513
[27]
[27]
[9]
131.64 (s) 133.86 (s)
170.46 (s) 168.69 (s)
133.63 (s)
168.35 (s)
133.20 (s)
168.90 (s)
[(SnPh3).BPPY]Cl
[Pd{C6F5)(PPh3}2(APPY)]ClO4
s, singlet; d, doublet; (o), ortho; (m), meta; (p), para; (i), ipso; br, broad.
APPY = acetylmethylenetriphenylphosphorane;
BPPY = benzoylmethylenephenylphosphorane.
a
Recorded in CDCl3.
b
Recorded in DMSO-d6.
Table 2
Ag(I) [23], which had been explained by fast exchange of the ylide
with the metal.
1H and 31P NMR data of BAPPY and its complexes with Hg(II) halides
Compound
d (CH)
2JPH
d (PPh3)
d (31P)
3.4. Crystal structures analysis
BAPPY
2.93 (br)
4.31 (br)
4.17 (br)
4.19 (br)
–
–
–
–
7.16–7.88 (m)
7.25–7.85 (m)
7.26–7.95 (m)
7.35–8.05 (m)
15.04 (s)
23.22 (s)
21.85 (s)
20.24 (s)
BAPPY ꢀ HgCl2
BAPPY ꢀ HgBr2
BAPPY ꢀ HgI2
Table 4 provides the crystallographic results and refinement
information for complex 3. The molecular structure of 3 is shown
in Fig. 1. Fractional atomic coordinates and equivalent isotropic
displacement coefficients (Ueq) for the non-hydrogen atoms of
complex 3 and a view of the crystal packing are shown in Fig. S1.
Table 5 lists key bond lengths and angles for complex 3.
(T = 298 K; J in Hz; TMS d = 0.00 ppm). Recorded in CDCl3, values (ppm) relative to
internal TMS and external 85% phosphoric acid. s, singlet; m, multiplet; br, broad.
spectra. The appearance of single signals for the PCH group in both
the 31P and 1H NMR spectra at ambient temperature indicates the
presence of only one molecule for all the three complexes, as ex-
pected for C-coordination. It must be noted that O-coordination
of the ylide leads to the formation of cis and trans isomers which
would give rise to two different signals in the 31P and 1H NMR
spectra [6b]. The resonances in the 31P NMR spectra of complexes
1, 2 and 3 were observed to occur at a lower field with respect to
the free ylide (Table 2). A comparison of the 31P chemical shift of
the three complexes at ambient temperature indicates a decrease
in the order 1 > 2 > 3. The 13C NMR data of the complexes and
the title ylide, along with possible assignments, are listed in Table
3.
The dimeric structure adopted by complexes 1, 2 and 3 is in
contrast to the O-coordinated trinuclear mercury(II) complex of
the phosphorus ylide Ph3PCHCOPh [24], but is similar to the struc-
ture of the C-coordinated dinuclear mercury(II) halide complexes
of Ph3PCHCOOEt (EPPY) [25a] and Ph3PCHCOPh (BPPY) [25b]. The
C-coordination of BAPPY is in stark contrast to the O-coordination
of the phosphorus ylide Ph3PC(COCH3)(COC6H5) (ABPPY) to the
Hg(II) center [26]. The difference in coordination mode between
ABPPY and BAPPY to Hg(II) can be rationalized in terms of the elec-
tronic properties and steric requirements of the ylides. The nucle-
ophilicity of the carbanion in ABPPY is less than for BAPPY; this is
due to the additional delocalization of the ylide electron density in
ABPPY which is facilitated by the second carbonyl group. This will
reduce the ability of ABPPY to bind via the ylidic carbon. Belluco
et al. have studied steric influences on the coordination modes of
ylide molecules to Pt(II) systems [27]. These authors concluded
that the preferred coordination mode is via the ylidic carbon, but
that steric hindrance around the metal center or the ylidic carbon
will necessitate O-coordination. Indeed, this trend is reflected here,
both BPPY and BAPPY are slightly less sterically demanding than
The 13C shifts of the CO group in the complexes are around
168 ppm, which is higher field than the 170 ppm noted for the
same carbon in the parent ylide, indicating much higher shielding
of the carbon atom of the CO group in the complexes [21]. No cou-
pling to Hg was observed at room temperature in the 1H, 13C and
31P NMR spectra. Failure to observe satellites in the above spectra
was previously noted in the ylide complexes of Hg(II) [22] and

1966
S.J. Sabounchei et al. / Polyhedron 27 (2008) 1963–1968
ABPPY and are both C-coordinated to Hg(II). The Hg(II) in 3 is sp3
hybridized and has a tetrahedral coordination environment with
one short Hg–I bond, one Hg–C bond and two asymmetric bridging
Hg–I bonds at distances of 2.841(9) and 3.129(8) Å. The signifi-
cance of the Hg–C bond of length, 2.263(6) Å, compared to analo-
gous distances in [BPPY ꢀ HgI2]2 [25] and [(C6H5)3PC5H4 ꢀ HgI2]2
[22] (2.312(13) and 2.292(8) Å, respectively) must be attributed
to the use of Hg(II) orbitals with high s character for bonding to
the ylidic carbon. The use of non-equivalent hybrid orbitals with
high s character to bond to low electronegative atoms was pro-
posed by Bent in the concept of isovalent hybridization to account
for the variation in bond lengths and bond angles around a central
Table 4
Crystal data and refinement parameter for 3
Table 5
Empirical formula
Formula weight
Temperature (K)
Wavelength (Å)
Crystal system, space group
Unit cell dimensions
a (Å)
C54H46I4Hg2O4P2
1729.63
293(2)
0.71073
monoclinic, P21=c
A comparison between the selected calculated bond lengths (Å) and bond angles (°)
for compound 3 with X-ray data
X-ray
B3LYP/Lanl2mb
Bond lengths
Hg(1)–C(1)
Hg(1)–I(1)
Hg(1)–I(2)
Hg(1)–I(2)#1
P(1)–C(1)
P(1)–C(10)
P(1)–C(16)
P(1)–C(22)
2.263(6)
2.341
3.042
3.197
3.316
1.969
1.949
1.940
1.961
20.493(4)
12.496(3)
23.293(5)
109.52(3)
5623(2)
4, 2.043
7.748
32.16
2.6719(9)
2.8410(9)
3.1296(8)
1.783(6)
1.792(6)
1.808(7)
1.806(7)
b (Å)
c (Å)
b (°)
Volume (A3)
Z, Dcalc (Mg/m3)
Absorption coefficient (mmꢂ1
F(000)
)
Bond angles
Crystal size (mm)
Theta Range for data collection (°)
Limiting indices
0.35 ꢁ 0.30 ꢁ 0.20
C(1)–Hg(1)–I(1)
C(1)–Hg(1)–I(2)
I(1)–Hg(1)–I(2)
C(1)–Hg(1)–I(2)#1
I(1)–Hg(1)–I(2)#1
I(2)–Hg(1)–I(2)#1
C(1)–P(1)–C(10)
C(1)–P(1)–C(16)
C(10)–P(1)–C(22)
C(22)–P(1)–C(16)
C(10)–P(1)–C(16)
O(1)–C(2)–O(2)
O(1)–C(2)–C(1)
O(2)–C(3)–C(4)
P(1)–C(1)–Hg(1)
129.12(15)
113.42(16)
111.88(3)
96.84(15)
102.57(3)
93.22(3)
115.4(3)
108.4(3)
106.8(3)
107.4(3)
108.3(3)
123.4(6)
126.4(6)
114.0(6)
113.1(3)
135.91
105.293
103.448
99.912
111.639
92.252
109.17
109.74
106.81
107.10
109.84
123.62
131.18
111.41
118.45
1.62–26.81
ꢂ25 6 h 6 23, ꢂ15 6 k 6 15,
ꢂ29 6 l 6 29
33902/11871 [R(int) = 0.0442]
98.60
Reflections collected/unique
Completeness to Theta = 23.78° (%)
Absorption correction
Maximum and minimum transmission
Refinement method
numerical
0.212 and 0.083
full-matrix least-squares on F2
11871/0/595
1.139
0.0514, 0.0854
0.0755, 0.0928
0.920 and ꢂ1.004
Data/restraints/parameters
Goodness-of-fit on F2
a
Final R1, wR2 (observation data)
a
Final R1, wR2 (All data)
Largest diffraction peak and hole
(e Aꢂ3
)
2
2 1=2
R1 ¼ RkFoj ꢂ jFck=RjFoj; wR2 ¼ ½RðwðF2o ꢂ Fc2Þ Þ=RwðFo2Þ ꢃ
.
a
Fig. 1. Molecular structure of the complex [(BAPPY) ꢀ HgI2]2. H atoms are omitted for clarity.

S.J. Sabounchei et al. / Polyhedron 27 (2008) 1963–1968
1967
atom. The internuclear distances between mercury atoms were
found to be 4.090(5), 4.014(1) and 3.810(2) Å in the structures 3,
[BPPY ꢀ HgI2]2 and [BPPY ꢀ HgCl2]2, respectively. These distances
are much longer than the sum of the Van der Waals radii (1.5 Å)
of the two mercury atoms [28] indicating the absence of significant
bonding interactions between the mercury atoms in the molecular
structures. The adaptation of dimeric structures in the Hg(II) ylide
complexes may be explained by both the preference of Hg(II) for
four coordination and the stability of the 18 electron configuration
around Hg(II).
transfer will occur by a contribution from the mixing of the filled
orbital of one component molecule with the vacant orbital of an-
other. The most important terms in this kind of interaction are
contributed from the partial charge transfer between the HOMO
of one component and the LUMO of another. The HOMO–LUMO
(H–L) energy gap is large in magnitude for this complex and cor-
responds to 4.161 eV. As listed in Table 6, the dipole moment of
the trans complex in the x, y and z planes was only 0.0 De. This
result shows that the complex has no polarity in the three planes.
The structure of the HOMO and LUMO are shown in Figs. 3a
and 3b.
3.5. Theoretical studies
The optimized structure of this compound is shown in Fig. 2 and
selected bond lengths and bond angles are given in Table 5.
As can be seen, the calculated bond lengths are slightly longer
than the measured bond lengths but the similarity of calculated
and measured bond angles reflects the similar geometrical struc-
tures for this compound in both the solid state and gas-phase. It is
clear that the dimeric structure with the general formula [BAP-
PY ꢀ HgX2]2 can be considered as both the observed trans-like or
Table 6
Energies, partial charges, dipole moment (De), quadrupole moment (De) and HOMO
and LUMO energy of the B3LYP/lanl2mb optimized trans structure at the DFT/
LanL2MB level of theory
Species
Values
E (eV)
ꢂ68048.41
ꢂ4.403
ꢂ0.242
4.161
HOMO (eV)
LUMO (eV)
H–L (eV)
possible cis-like isomers. Table
5 shows the complete data
collections for the X-ray results and theoretical calculation. In
the trans-like structure of the compound, the internuclear dis-
tances between the mercury atoms were calculated to be
4.514 Å, indicating the absence of significant bonding interactions
between the mercury atoms in the molecular structure. The Hg–C
bond length in the trans structure is calculated to be 2.341 Å. A
comparison of the bond lengths and bond angles from both meth-
ods (X-ray crystallography and quantum calculation) shows that
the results of the calculation are the same as the X-ray crystallog-
raphy results. For example the distances: P(1)–C(1), P(1)–C(10),
P(1)–C(16), P(1)–C(22) have approximately equal values. These
data show that the phenyl rings attached to phosphorus have
little effect on the bond lengths between the phosphorus and
carbon atoms. The stability energy values for this complex are re-
ported in Table 6.
Charge s (esu)
Hg(1)
C(1)
C(2)
C(3)
C(4)
P(1)
O(1)
O(2)
0.202
ꢂ0.150
0.228
ꢂ0.043
ꢂ0.008
0.201
ꢂ0.198
ꢂ0.114
Dipole moment (De)
X
0.00
Y
0.00
Z
0.00
Quadrupole moment (De)
XX
YY
ZZ
ꢂ392.29
ꢂ399.01
ꢂ379.54
XY
XZ
YZ
Furthermore, the energies of the HOMO and LUMO for the
complex are summarized in Table 6. In this case, partial charge
ꢂ45.0531
104.66
ꢂ43.59
Fig. 2. Optimized structure of the complex [(BAPPY) ꢀ HgI2]2.

1968
S.J. Sabounchei et al. / Polyhedron 27 (2008) 1963–1968
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4. Conclusions
The present study describes the synthesis and characterization
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formula [BAPPY.HgX2]2 (X = Cl, Br, I). On the basis of the physico-
chemical and spectroscopic data we propose that BAPPY herein
exhibits monodentate C-coordination to the metal center. In addi-
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Appendix A. Supplementary data
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CCDC 648218 contains the supplementary crystallographic data
for 3. These data can be obtained free of charge via http://
www.ccdc.cam.ac.uk/conts/retrieving.html, or from the Cambridge
Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ,
UK; fax: (+44) 1223-336-033; or e-mail: deposit@ccdc.cam.ac.uk.
Supplementary data associated with this article can be found, in
the online version, at doi:10.1016/j.poly.2008.03.010.