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

Article abstract of DOI:10.1016/j.jorganchem.2007.02.027

A new carbbenzyloxymethylenetriparatolylphosphorane ylide (BTPY), {(p-tolyl)₃PCHCOOCH₂C₆H₅},wa s synthesized and characterized with elemental analysis as well as various spectroscopic techniques. The reactions o

Full text of DOI:10.1016/j.jorganchem.2007.02.027

Journal of Organometallic Chemistry 692 (2007) 2500–2507
www.elsevier.com/locate/jorganchem
Synthesis of a new carbbenzyloxymethylenetriparatolylphosphorane
ylide and study of its reaction with mercury(II) halides: Spectral
and structural characterization
a,
a
a
Seyyed Javad Sabounchei *, Alireza Dadrass , Mojtaba Jafarzadeh ,
a
b
Sadegh Salehzadeh , Hamid Reza Khavasi
a
Faculty of Chemistry, Bu-Ali Sina University, Hamadan, Iran
Department of Chemistry, Shahid Beheshti University, Evin, Tehran 1983963113, Iran
b
Received 12 December 2006; received in revised form 18 February 2007
Available online 24 February 2007
Abstract
A new carbbenzyloxymethylenetriparatolylphosphorane ylide (BTPY), {(p-tolyl)3PCHCOOCH2C6H5},was synthesized and charac-
terized with elemental analysis as well as various spectroscopic techniques. The reactions of the title ylide with mercury(II) chloride, mer-
cury(II) bromide and mercury(II) iodide in equimolar ratios using dry methanol as solvent have yielded [BTPY Æ HgCl2]2 (1),
[BTPY Æ HgBr2]2 (2) and [BTPY Æ HgI2]2 (3), respectively. Single crystal X-ray analysis of 2 reveals the presence of a centrosymmeteric
1
dimeric structure containing the ylide and HgBr2. The analytical data, IR and H, 13C and 31P NMR data for the latter compound are
similar to those of 1 and 3, indicating similar structures. The theoretical studies indicated that, for all three compounds, the observed
trans-like structure for compound 2, is more stable than the possible cis-like structure in each case.
ꢀ 2007 Elsevier B.V. All rights reserved.
Keywords: Phosphorus ylide; Mercury(II) halides complexes; X-ray crystal structure; Theoretical studies
1. Introduction
and thus bond to an Hg(II) centre through the either carb-
anion (b) or the enolate oxygen (c).
Phosphorus ylides are reactive compounds, which take
part in many reactions of value in the synthesis of organic
products [1–4]. They are synthetic targets of interest,
because of their value for a variety of industrial, biological
and chemical synthetic uses [5–7]. Juxtaposition of the keto
group and carbanion in the phosphorus ylide, BTPY
allows for the resonance delocalization of the ylidic elec-
tron density providing additional stabilization to the ylide
species (Scheme 1). This so-called a-stabilization provides
BTPY with the potential to act as an ambidentate ligand
Although many bonding modes are possible for keto
ylides [8], coordination through carbon is more predomi-
nant and observed with soft metal ions, e.g., Pd(II),
Pt(II), Ag(I), Hg(II), Au(I) and Au(III) [9–13], whereas,
O-coordination dominates when the metals involved are
hard, e.g., Ti(IV), Zr(IV), and Hf(IV) [14]. In this work
we have synthesized benzyloxy stabilized phosphorus ylide
and metal complexes with mercury(II) halides. The aims
of our present work are (i) to determine and compare
the molecular structure of the products formed by the title
ylide with mercury(II) halides, and (ii) to characterize all
1
the products by IR, H, 13C and 31P NMR spectra and X-
*
Corresponding author. Tel.: +98 811 8272072; fax: +98 811 8257407.
E-mail address: Jsabounchei@yahoo.co.uk (S.J. Sabounchei).
ray crystallography.
0022-328X/$ - see front matter ꢀ 2007 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2007.02.027

S.J. Sabounchei et al. / Journal of Organometallic Chemistry 692 (2007) 2500–2507
2501
2.3. Computational methods
(p-tolyl)3P
(p-tolyl)3P
(p-tolyl)3P
The geometries of all compounds were fully optimized
at the Hartree–Fock (HF) (B3LYP) level of theory using
the GAUSSIAN98 program [22] on a Pentium-PC computer
with 3000 MHz processor. The standard LanL2MB basis
set was used for both complexes [23]. This basis set
includes effective core potentials (ECP) for both the mer-
cury and phosphorous as well as halide (Cl, Br, I) ions.
Vibrational frequency analyses, calculated at the same
level of theory, indicate that optimized structures are
at the stationary points corresponding to local minima,
without any imaginary frequency. Atomic coordinates
for ab initio calculations were obtained from the
data of the X-ray crystal structure analyses for com-
pound 2.
O
OR
O
OR
O
OR
a
b
c
Scheme 1. The canonical forms of BTPY (R = CH2Ph).
2. Experimental section
2.1. Physical measurements and materials
Methanol was distilled over magnesium powder and
diethyl ether (Et2O) over a mixture of sodium and benzo-
phenone just before use. All other solvents were reagent
grade and used without further purifications. Solution-
state 1H, 31P and 13C NMR spectra at ambient temperature
were obtained in DMSO-d6 or CDCl3 using a 200 MHz
Bruker spectrometer. Solution-state 1H and 31P NMR
spectra at 220 K were obtained in CDCl3 using a
500 MHz Bruker spectrometer operating at 500.13 MHz
for 1H, and 202.45 MHz for 31P. Melting points were mea-
sured on a SMPI apparatus. Elemental analysis for C, H
and N were performed using a PE 2400 series analyzer.
IR spectra were recorded on a Shimadzu 435-U-04 spectro-
photometer and the measurements were made by the KBr
disk method. X-ray analysis was recorded on a STOE
IPDS-II diffractometer.
2.4. Sample preparation
2.4.1. Synthesis of [(p-tolyl)3PCHCOOCH2C6H5]
(BTPY)
Benzylbromoacetate (0.42 g, 2 mmol) was dissolved in
20 ml of chloroform and then a solution of triparatolyl-
phosphine (0.557 g, 2 mmol) in the same solvent (5 ml)
was added dropwise to the above solution. The resulting
pale yellow solution was stirred for 10 h. The solution
was concentrated under reduced pressure to 5 ml, and
diethyl ether (20 ml) was added. The yellow solid formed
was filtered off, washed with petroleum benzene (10 ml),
and dried under reduced pressure. In order to get the final
product, all of the crude solid, 0.75 g (81.5%), was trans-
ferred to an alkaline solution of 5% NaOH and stirred at
40 ꢁC for about 14 h, yielding the pale white precipitate.
The product was washed several times with distilled water
and air dried. Yield 0.59 g (85.5%), m.p. 101–103 ꢁC. Anal.
Calc. for C30H29O2P: C, 79.62; H, 6.46. Found: C, 79.78;
H, 6.54%.
2.2. X-ray crystallography
A block colorless crystal of 2 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).
2.4.2. Synthesis of [(BTPY) Æ HgCl2]2 (1)
The data were collected at a temperature of 298 K to a
maximum h value of 26.78ꢁ and in a series of x scans in
1degr oscillations with 60 s exposures. Of the 15671 reflec-
tions that were collected, 6136 were unique (Rint = 0.0345),
equivalent reflections were merged. Data were collected
and integrated using the STOE X-AREA [15] software package.
The numerical absorption coefficient, l, for Mo Ka radia-
tion is 8.109 mmꢀ1. A numerical absorption correction was
applied using X-RED [16] and X-SHAPE [17] softwares, which
resulted in transmission factors ranging from 0.242 to
0.378. The data were corrected for Lorentz and polarizing
effects. The structure was solved by direct [18] methods. All
of the none-hydrogen atoms were refined anisotropically.
All of hydrogen atoms were located in the ideal positions.
Anomalous description effects were included in Fcalc [19],
the values for Df0 and Df00 were those of Creagh and McAu-
ley [20]. The values for the mass attenuation coefficient are
those of Creagh and Habbell [21].
A solution of 0.09 g (0.3 mmol) of HgCl2 in methanol
(15 ml) was added to a solution of 0.15 g (0.3 mmol) of
BTPY in dry methanol and stirred for 12 h. The white solu-
tion was concentrated to 2 ml, and diethyl ether (15 ml)
added to precipitate the white complex. Yield 0.202 g
(84.2%), m.p. 173–175 ꢁC. Anal. Calc. for C60H58Cl4Hg2O4
P2: C, 49.77; H, 4.04. Found: C, 50.57; H, 3.82%.
2.4.3. Synthesis of [(BTPY) Æ HgBr2]2 (2)
A solution of 0.14 g (0.4 mmol) of HgBr2 in methanol
(15 ml) was added to a solution of 0.172 g (0.4 mmol) of
BTPY in dry methanol and stirred for 8 h. The white solu-
tion was concentrated to 2 ml, and diethyl ether (15 ml)
added to precipitate the white complex, which was recrys-
tallized from chloroform–diethyl ether.
Yield 0.266 g (85.8%), m.p. 176–178 ꢁC. Anal. Calc. for
C60H58Br4Hg2O4P2: C, 44.32; H, 3.6. Found: C, 44.55; H,
3.47%.

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Table 2
2.4.4. Synthesis of [(BTPY) Æ HgI2]2 (3)
1H and 31P NMR data of BTPY and its complexes with Hg (II) halide
A solution of 0.18 g (0.4 mmol) of HgI2 in methanol
(15 ml) was added to a solution of 0.178 g (0.4 mmol) of
BTPY in dry methanol and stirred for 6 h. The yellow solu-
tion was concentrated to 2 ml, and diethyl ether (15 ml)
added to precipitate the pale yellow complex. Yield 0.31 g
(86.1%), m.p. 184–187 ꢁC. Anal. Calc. for C60H58I4H-
g2O4P2: C, 39.73; H, 3.22. Found: C, 38.94; H, 3.1%.
(T = 298 K; J in Hz; TMS d = 0.00 ppm)
Compound
d (CH)
2J (PH)
d(P(p-tolyl)3)
d (31P)
BTPYa
BTPY Æ HgCl2
BTPY Æ HgBr2
BTPY Æ HgI2
2.88(d)
4.25(br)
4.07(br)
3.94(br)
15.59
7.16–7.88(m)
7.23–8.21(m)
7.48–8.11(m)
7.50–8.21(m)
13.90(s)
23.85(s)
21.66(s)
20.96(s)
a
a
–
–
–
a
br, broad; s, singlet; d, doublet; m, multiplet.
a
In CDCl3, values (ppm) relative to internal TMS.
3. Results and discussion
The expected downfield shifts of 31P and 1H signals for the
PCH group upon complexation were observed in their corre-
sponding spectra. The appearance of single signals for the
PCH group in both the 31P and 1H NMR at ambient temper-
ature indicates the presence of only one molecule for all the
three complexes as expected for C-coordination. It must be
noted that O-coordination of the ylide sometimes leads to
the formation of cis and trans isomers giving rise to two dif-
ferent signals in the 31P and 1H NMR [9,14]. The resonances
of the 31P NMR complexes 1, 2, and 3 were observed to occur
at a lower field with respect to the free ylide (Table 2). Com-
parison of the 31P spectra of the three complexes at ambient
temperature indicates that decreases in the order 1 > 2 > 3.
At low temperature (220 K), exhibite satellites due to cou-
pling to 199Hg (8% intensity each, 2JP–Hg ꢁ 201 Hz).
3.1. Spectroscopy
The m(CO), which is sensitive to complexation, occurs at
1615 cmꢀ1 in the parent ylide, as in the case of other reso-
nance stabilized ylides [24]. 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 com-
plexes at 1702, 1699 and 1692 cmꢀ1 indicate coordination,
of the ylide through carbon. The m(P+–Cꢀ), which is also
diagnostic for the coordination occurs at 851 cmꢀ1 in
(p-tolyl)3P+–CꢀH2 and at 811 cmꢀ1 in (C6H4CH3)3-
PCHCOOCH2C6H5. In the present study, the m(P+–Cꢀ)
values for all three complexes were shifted to lower fre-
quencies and observed at 805, 806 and 806 cmꢀ1 for 1, 2,
and 3, respectively, suggesting some removal of electron
density in the P–C bond.
The 13C NMR data of the complexes and the title ylide
are listed in Table 3 along with possible assignments. The
most interesting aspect of the 13C spectra of the complexes
is the upfield shift of the signals due to the ylidic carbon.
Such upfield shifts observed in PdCl (g3-2-XC3H4)
(C6H5)3PCHCOR (X = H, CH3; R = CH3, C6H5) was
attributed to a change in hybridization of the ylidic carbon
[28]. Similar upfield shifts of 4–9 ppm with reference to the
parent ylide were also observed [29] in the case of
[(C6H5)3PC5H4HgI2]2, and in our synthesized mercury
complexes [30]. The 13C shifts of the CO group in the com-
plexes are around 169 ppm, which is higher than the
170 ppm shift noted for the same carbon in the parent
ylide, indicating much higher shielding of the carbon of
the CO group in the complexes. No coupling to Hg was
The 1H NMR data for the mercury(II) complexes along
with those of the parent ylide are listed in Table 2. The sig-
nal due to the methine proton, when recorded in CDCl3,
was broad for complexes 1, 2, and 3. This indicates proba-
bly, that the ylide dissociate in solution. Compounds
2
wherein the ylide is C-coordinated exhibit a J(PH) value
10 or less Hz [12,8,33].
Table 1
m (CO) of selected phosphoranes and their metal complexes
Compound
m (CO) cmꢀ1
Reference
1
observed at room temperature in H, 13C and 31P NMR
Ph3PCHCON(CH3)2
Ph3PCHCOCH3 (APPY)
Ph3PCHCOPh (BPPY)
1530
1530
1525
1615
[24]
[25]
[26]
This work
spectra of all these complexes.
3.2. X-ray crystallography
(C6H4CH3)3PCHCOOCH2C6H5 (BTPY)
C-coordination
Table 4 provides the crystallographic results and refine-
ment information for complex 2. The refinement was per-
formed using the X-STEP32 [31] crystallographic software
package. The molecular structure of 2 is shown in
Fig. 1a. Fractional atomic coordinates and equivalent iso-
tropic displacement coefficients (Ueq) for the non-hydrogen
atoms of complex 2 (are shown in Table S1). Table 5 lists
key bond lengths and angles for complex 2.
BTPY Æ HgCl2 (1)
BTPY Æ HgBr2 (2)
BTPY Æ HgI2 (3)
BPPY Æ HgCl2
BPPY Æ HgBr2
Au [CH(PPh3)CON(CH3)2]
1702
1699
1692
1635
1630
1605
This work
This work
This work
[12]
[12]
[24]
O-coordination
[(Sn(CH3)3 Æ BPPY]Cl
[(SnPh3) Æ BPPY]Cl
1480
1470
1513
[27]
[27]
[9]
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, [32] but
[Pd{C6F5)(PPh3}2(APPY)]ClO4
APPY = acetylmethylenetriphenylphosphorane.
BPPY = benzoylmethylenephenylphosphorane.

S.J. Sabounchei et al. / Journal of Organometallic Chemistry 692 (2007) 2500–2507
2503
Table 3
13C NMR data of BTPY and its complexes with mercury (II) halides
BTPYa
BTPY Æ HgCl2
BTPY Æ HgBr2
BTPY Æ HgI2
b
a
b
Possible assignments
(CH)
1J(PC)
30.5(d)
125.03
br
–
br
–
br
–
CH2
CH3
63.37(s)
21.66(s)
144.85(s)
127.56(s)
127.26(s)
126.50(s)
124.41(d)
94.16
66.32(s)
21.01(s)
144.44(s)
128.00(s)
128.00(s)
128.00(s)
118.72(d)
91.66
67.18(s)
21.72(s)
144.96(s)
128.91(s)
128.22(s)
127.86(s)
119.46(d)
92.18
51.4(s)
21.06(s)
144.11(s)
130.26(s)
128.75(s)
127.95(s)
119.74(d)
92.72
(CH2–Ph)(i)
(CH2–Ph)(o)
(CH2–Ph)(m)
(CH2–Ph)(p)
P(p-tolyl)3(i)
1J(PC)
P(p-tolyl)3(o)
2J(PC)
132.51(d)
10.21
133.13(d)
10.38
133.47(d)
9.48
133.04(d)
10.48
P(p-tolyl)3(m)
3J(PC)
129.02(d)
12.66
130.07(d)
12.80
130.54(d)
13.00
130.00(d)
11.78
P(p-tolyl)3(p)
(CO)
138.44(s)
170.39(s)
135.55(s)
168.62(s)
136.13(s)
169.46(s)
133.27(s)
169.66(s)
s, singlet; d, doublet; (o), ortho; (m), meta; (i), ipso carbon; br, broad.
a
Record in CDCl3.
Record in DMSO-d6.
b
Table 4
(BPPY) [12]. The C-coordination of BTPY is in stark con-
trast to the O-coordination of the phosphorus ylide
Ph3PC(COMe)(COPh) (ABPPY) to the Hg(II) centre
[34]. The difference in coordination mode between ABPPY
and BTPY to Hg(II) can be rationalized in terms of the
electronic properties and steric requirements of the ylides.
The nucleophilicity of the carbanion in ABPPY is less than
for BTPY; 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 [35]. These authors concluded
that the preferred coordination mode is via the ylidic car-
bon, but that steric hindrance around the metal centre or
the ylidic carbon will necessitate O-coordination.
Crystal data and refinement parameter for 2
Empirical formula
Formula weight
Temperature (K)
Wavelength (A)
Crystal system, space group
Unit cell dimensions
C60H58Br4Hg2O4 P2
1625.78
293(2)
0.71073
˚
Monoclinic, P21/c
˚
a (A)
11.2864(12)
10.3313(7)
25.149(3)
90
˚
b (A)
˚
c (A)
a (ꢁ)
b (ꢁ)
c (ꢁ)
Volume
96.751
90
2912.1(5) A
3
˚
ˆ 3
Z, Calculated density
Absorption coefficient
F(000)
Crystal size
Theta range for data collection
Limiting indices
2, 1.854 Mg/m
8.109 mmꢀ1
1560
0.25 · 0.15 · 0.12 mm
1.63–26.78ꢁ
Indeed, this trend is reflected here, both BPPY and
BTPY are slightly less sterically demanding than ABPPY,
and are both C-coordinated to Hg(II). The Hg(II) in 2 is
sp3 hybridized and has a tetrahedral coordination environ-
ment with one short Hg–Br bond, one Hg–C bond and two
asymmetric bridging Hg–Br bonds at the distances of
ꢀ14 6 h12, ꢀ11 6 k 6 13,
ꢀ31 6 1 6 31
Reflections collected/unique
Completeness to theta = 23.78
Absorption correction
Maximum and minimum
transmission
15671/6136 [Rint = 0.0345]
98.60%
Numerical
0.378 and 0.242
˚
2.753(5) and 2.780(5) A. The significant of the Hg–C bond
Refinement method
Full-matrix least-squares on F2
6136/0/325
˚
of length, 2.226(4) A compared to analogous distances in
Data/restraints/parameters
Goodness-of-fit on F2
Final R indices
[BPPY. HgI2]2 (4) [12] and in [(C6H5)3PC5H4 Æ HgI2]2 [28]
1.07
˚
R1a = 0.0313, wR2b = 0.0582
R1 = 0.0401, wR2 = 0.0608
(2.312(13) and 2.292(8) A, respectively) must be attributed
to the use of Hg (II) orbitals with high s character for
bonding to ylidic carbon.
R indices (all data)
ꢀ3
˚
Largest difference in peak and hole 3.179 and ꢀ0.740 e A
P
P
a
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 atom. As expected on the basis of the same
concept, the Hg–C bonds in 2 and [BPPY. HgCl2]2 (5) [12]
are much shorter than in 4, because of the very low difference
in electronegativity between carbon and iodine.
R1 ¼ jjF oj ꢀ jF cjj= jF oj for reflection with I > 2rI.
P
P
2
2 1=2
b
wR2 ¼ ½ ðwðF 2o ꢀ F c2Þ Þ= wðF 2oÞ ꢂ
.
is similar to the structure of l-dichlorobis[chloro-
(benzoylmethylenetri-n-butylphosphorane)palladium(II)]
reported by Albanese et al. [33] and the C-coordinated
dinuclear mercury(II) halide complexes of Ph3PCHCOPh

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S.J. Sabounchei et al. / Journal of Organometallic Chemistry 692 (2007) 2500–2507
Fig. 1. (a) ORTEP view of X-ray crystal structure of 2, (b) calculated molecular structure of trans- [BTPY Æ HgBr2]2 and (c) calculated molecular structure
of cis-[BTPY Æ HgBr2]2.
The internuclear distances between mercury atoms were
found to be 3.951(5), 4.014(1), and 3.810(2) A in structures
bond angles reflects the similar geometrical structures for
this compound in both the solid state and gas-phase. It is
clear that the dimeric structure with general formula
[BTPY Æ HgX2]2 can be considered as both the observed
trans-like or possible cis-like isomers. Thus we changed
the geometrical structure of compound 2, by replacement
of positions of one terminal bromine atom with one coor-
dinated ylide group, to obtain a cis-like isomer. The mini-
mization of this isomer at same level of theory gave the
desired cis-like isomer as it has been shown in Fig. 1c.
But we found that this structure is about 5.4 kcal/mol less
stable than trans-like structure. We have also studied the
gas phase structures of [BTPY Æ HgCl2]2 and [BTPY Æ
HgI2]2 complexes in a similar way. We could optimize a
cis-like isomer for the former complex which was about
5.9 kcal/mol less stable than trans-like isomer (Fig. 2). On
the other hand we never were able to optimize acis-like iso-
mer for compound 3. It was very interesting that any con-
sidered cis-like structure for this compound, has been
changed to a trans-like structure (Fig. 3).
˚
2, 4, and 5, respectively. These distances are much longer
˚
than the sum of Van der Waals radii (1.5 A) of the two
mercury atoms [36] indicating the absence of significant
bonding interactions between the mercury atoms in the
molecular structures.
The adaptation of dimeric structures in 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).
3.3. Theoretical studies
As mentioned in Section 2.3, the analytical and spectro-
scopic data for compound 2 are similar to those of the
other two complexes synthesized here. We were interested
to see whether the observed trans-like structure for com-
pound 2 is more stable than its possible cis-like isomer
and whether this is the case for other compounds. Thus
the observed geometry of compound 2 was considered for
ab initio calculations. The optimized structure of this com-
pound is shown in Fig. 1b and the selected bond lengths
and bond angles are given in Table 5. As can be seen, the
calculated bond lengths are slightly longer than measured
bond lengths but the similarity of calculated and measured
In the trans-like structures of compounds 1, 2, and 3 the
internuclear distances between mercury atoms were calcu-
˚
lated to be 4.091, 4.250, and 4.420 A, indicating the
absence of significant bonding interactions between the
mercury atoms in the molecular structures (Tables 5
and 6). The Hg-C bond length in the latter structures are

S.J. Sabounchei et al. / Journal of Organometallic Chemistry 692 (2007) 2500–2507
2505
Table 5
sible structures. Obviously upon C-coordination to metal
ions the structure (b) will be the unique or predominant
structure. This was confirmed by comparison of the calcu-
lated bond lengths for C(27)–C(43) (Fig. 1) in the free ylide,
˚
A comparison between the calculated bond lengths (A) and bond angles
(ꢁ) for the compound 2 with corresponding experimental values
X-ray
HF/Lanl2mb
˚
Bond lengths
Hg(46)–Br(21)
Hg(46)–Br(21) #1
Hg(46)–Br(59)
P(44)–C(62)
P(44)–C(37)
P(44)–C(43)
P(44)–C(40)
Hg(46)–C(43)
1.509 A, and its complexes 1, 2, and 3, 1.537, 1.538,
2.7533 (5)
2.947
2.986
2.778
1.960
1.916
1.925
1.929
2.248
˚
1.538 A, respectively.
2.7800 (5)
2.5255 (6)
1.805 (4)
1.789 (4)
1.791 (4)
1.800 (4)
2.226 (4)
4. Conclusions
A new ylide (BTPY), and its mercury(II) complexes with
the general formula [BTPY Æ HgX2]2 (X = Cl, Br, I) have
been synthesized. Theoretical studies on the gas phase
structures of the latter complexes, confirm the trans-like
dimeric structure for compound 2 obtained by X-ray crys-
tal structure analyses. The observation of similar analytical
and spectroscopic data after further support the presence
of a centrosymmeteric dimeric structure containing the
ylide and HgX2.
Bond angles
Hg(46)–Br(21)–Hg(46)
Br(21)–Hg(46)–C(43)
Br(59)–Hg(46)–Br(59)
Br(21)–Hg(46)–Br(21) #1
Br(21)–Hg(46)–Br(59)
C(43)–Hg(46)–Br(57)
C(43)–Hg(46)–Br(59)
Br(21)–Hg(46)–Br(59) #1
Hg(46)–Br(57)–Hg(46) #1
Br(57)–Hg(46)–Br(21)
O(18)–C(27)–O(28)
O(18)–C(27)–C(43)
O(28)–C(27)–C(43)
C(14)–O(28)–C(27)
C(43)–P(44)–C(40)
C(62)–P(44)–C(40)
C(37)–P(44)–C(40)
C(43)–P(44)–C(37)
C(62)–P(44)–C(37)
C(62)–P(44)–C(43)
P(44)–C(43)–Hg(46)
91.14
104.790
106.00
88.864
114.001
104.886
130.095
106.004
91.136
88.86
123.445
124.866
111.683
114.858
114.72
108.10
109.29
109.23
108.32
106.99
114.005
91.50
106.846
107.85
88.502
107.305
110.830
128.181
107.851
91.496
88.50
125.448
126.265
108.283
113.071
111.13
109.66
110.28
110.25
108.04
109.46
114.353
˚
calculated to be 2.244, 2.248, and 2.251 A, respectively,
indicating the slight decreasing in the s character of the
Hg(II) orbitals in bonding to ylidic carbon with decreasing
electronegativity of coordinated halide ligands.
The optimized molecular structure of the ligand BTPY
(is shown in Fig. S1), along with selected calculated bond
lengths (is shown in Table S2). As can be seen in Scheme
1, the ylides in their free forms can be shown as three pos-
Fig. 3. Calculated molecular structure of trans-[BTPY Æ HgI2]2.
Fig. 2. Calculated molecular structure of (a) trans- [BTPY Æ HgCl2]2 and (b) cis-[BTPY Æ HgCl2]2.

2506
S.J. Sabounchei et al. / Journal of Organometallic Chemistry 692 (2007) 2500–2507
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Table 6
˚
Selected theoretical bond lengths (A) and bond angles (ꢁ) for the
calculated trans-like molecular structures of 1 and 3 at HF/LanL2MB
level of theory
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X = Cl
X = I
Bond lengths
X(66)–Hg(67)
X(65)–Hg(67)
X(69)–Hg(67)
P(71)–C(74)
P(71)–C(75)
P(71)–C(76)
P(71)–C(68)
C(70)–O(72)
C(70)–O(73)
Hg(67)–C(68)
2.743
2.818
2.618
1.929
1.916
1.925
1.959
1.217
1.384
2.244
3.236
3.141
2.975
1.931
1.918
1.922
1.958
1.217
1.383
2.251
Bond angles
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X(65)–Hg(67)–X(66)
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X(66)–Hg(67)–C(68)
X(66)–Hg(67)–X(69)
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Hg(67)–C(68)–C(70)
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C(68)–C(70)–O(72)
C(68)–C(70)–O(73)
O(72)–C(70)–O(73)
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C(68)–P(71)–C(74)
C(68)–P(71)–C(75)
C(68)–P(71)–C(76)
C(74)–P(71)–C(75)
C(74)–P(71)–C(76)
C(75)–P(71)–C(76)
94.711
85.289
87.730
92.269
105.583
107.777
116.998
107.179
125.853
108.500
113.891
126.478
108.087
125.425
113.096
112.018
111.642
109.551
108.187
109.518
108.018
109.893
112.091
109.918
104.882
106.711
125.369
110.650
113.699
126.377
108.223
125.395
113.172
112.081
111.250
108.993
110.251
109.962
106.235
110.128
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Acknowledgement
We are highly grateful to the university of Bu-AliSina
for a Grant and Mr. Zebarjadian for recording the NMR
spectra.
Appendix A. Supplementary material
CCDC 622775 contains the supplementary crystallo-
graphic data for 2. These data can be obtained free of
charge via http://www.ccdc.cam.ac.uk/conts/retrieving.
html, or from the Cambridge Crystallographic Data Cen-
tre, 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.jorganchem.
2007.02.027.
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