New mono and binuclear mercury(II) complexes of phosphorus ylides containing DMSO as ligand: Spectral and structural characterization

Article abstract of DOI:10.1016/j.jorganchem.2008.02.025

Reaction of phosphorus ylides Ph₃PCHC(O)C₆H₄NO₂ (Y′) and (p-tolyl)₃PCHC(O)C₆H₄Cl (Y″) with HgX₂ (X = Cl, Br and I) in equimolar ratios using methanol as solvent leads

Full text of DOI:10.1016/j.jorganchem.2008.02.025

Available online at www.sciencedirect.com
Journal of Organometallic Chemistry 693 (2008) 1975–1985
www.elsevier.com/locate/jorganchem
New mono and binuclear mercury(II) complexes of phosphorus
ylides containing DMSO as ligand: Spectral and structural
characterization
a,
a
a
*
Seyyed Javad Sabounchei , Hassan Nemattalab , Sadegh Salehzadeh ,
Mehdi Bayat a, Hamid Reza Khavasi b, Harry Adams c
a Faculty of Chemistry, Bu-Ali Sina University, Hamedan 65174, Iran
b Department of Chemistry, Shahid Beheshti University, Evin, Tehran 1983963113, Iran
c Department of Chemistry, University of Sheffield, Sheffield S3 7HF, UK
Received 20 January 2008; received in revised form 19 February 2008; accepted 20 February 2008
Available online 4 March 2008
Abstract
Reaction of phosphorus ylides Ph3PCHC(O)C6H4NO2 (Y0) and (p-tolyl)3PCHC(O)C6H4Cl (Y00) with HgX2 (X = Cl, Br and I) in
equimolar ratios using methanol as solvent leads to binuclear products. The bridge-splitting reaction of binuclear complex [(Y00) ꢀ HgI2]2
by DMSO yields the mononuclear complex [(Y00) ꢀ HgI2 ꢀ DMSO]. This bridge-splitting reaction can be also a method for the synthesis of
mononuclear products. C-coordination of ylides and O-coordination of DMSO are demonstrated by single crystal X-ray analyses of
binuclear complexes of [(Y0) ꢀ HgI2]2 and [(Y00) ꢀ HgI2]2 and mononuclear complex of [(Y00) ꢀ HgI2 ꢀ DMSO]. Characterization of the
1
obtained compounds was also performed by elemental analysis, IR, H, 31P, and 13C NMR. Theoretical studies on Hg(II) complexes
of Y0 show that the cis-like isomers are about 4–12 kcal/mol less stable than the trans-like structures and the relative energy of cis-
and trans-like isomers significantly depends on the size of the bridging halide. These studies on mercury complexes of Y00 show that,
formation of mononuclear complexes in DMSO solution in which DMSO acts as a ligand, energetically is more favorable than that
of binuclear complexes.
Ó 2008 Elsevier B.V. All rights reserved.
Keywords: Mercury(II) halide; Phosphorus ylide; DMSO; Triphenylphosphine; Triparatolylphosphine
1. Introduction
halide-bridged dimeric structure for Hg(II) halide com-
plexes whereas Kalyanasundari et al. [8] reported an asym-
metric halide-bridged dimeric structure in 1995. In 1985,
Sanehi et al. [9] reported a mononuclear Hg(II) complex
of phosphorus ylides without any structural characteriza-
tion. We have recently focused on the synthesis of mononu-
clear, binuclear [10,11] and polynuclear [12] complexes
derived from mercury(II) salts and phosphorus ylides.
The a-keto-stabilized phosphorus ylides R3P@C(R0)COR00
show interesting properties such as their high stability
and their ambidentate character as ligands (C- vs. O-coor-
dination) [13–16]. This ambidentate character can be ratio-
nalized in terms of the resonance forms A–C, together with
the isomeric form D (Chart 1).
Phosphorus ylides are important reagents in organic
chemistry, especially in the synthesis of naturally occurring
products with biological and pharmacological activities [1].
These compounds have been used as reducing agents in
coordination chemistry. The utility of metalated phospho-
rus ylides in synthetic chemistry has been well documented
[2–5]. Synthesis of complexes derived from phosphorus
ylides and Hg(II) halides was started in 1965 by Nesmeyanov
et al. [6]. In 1975, Weleski et al. [7] proposed a symmetric
*
Corresponding author. Tel.: +98 8118272072; fax: +98 8118273231.
E-mail address: jsabounchei@yahoo.co.uk (S.J. Sabounchei).
0022-328X/$ - see front matter Ó 2008 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2008.02.025

1976
S.J. Sabounchei et al. / Journal of Organometallic Chemistry 693 (2008) 1975–1985
H
H
B
according to internal TMS and external 85% phosphoric
acid. Coupling constants are given in Hz.
H
H
Ar3P
Ar3+P
C-
Ar3+P
Ar3+P
C
C
C
O-
R
C
R
R
-O
O
O
R
2.2. X-ray crystallography
A
C
D
H
H
H
The single crystal X-ray diffraction analyses for com-
plexes [(Y0) ꢀ HgI2]2 and [(Y00) ꢀ HgI2]2 were performed on
a STOE IPDS-II two circle diffractometer at 293(2) K,
using graphite monochromated Mo Ka X-ray radiation
(k = 0.7107 nm). The data collection was performed at
room temperature using the x-scan technique and using
the STOE X-AREA software package [25]. The crystal struc-
tures were solved by direct methods [26] and refined by
using X-STEP32 crystallographic software package [27]. All
of the non-hydrogen atoms were refined anisotropically.
All of hydrogen atoms were located in ideal positions.
Single crystal X-ray diffraction data for [(Y00) ꢀ HgI2 ꢀ
DMSO] was measured on a Bruker SMART 4000 APEX II
CCD diffractometer. Structure solution and refinement
was carried out using SHELXS-97 and SHELXL-97, respectively
[28,29]. The Structure was solved by direct methods and
refined by full matrix least squares methods on F2. All
non-hydrogen atoms were refined anisotropically. All
hydrogens were included in calculated positions.
Ar3+P
Ar3+P
M
C
C
O-
C(O)R
P+Ar3
R
M
O-
R
M
E
F
G
Chart 1.
Form B can be considered as leading to coordination by
the carbon atom to give a complex of form E, whereas iso-
mers C and D would both lead to coordination by the oxy-
gen atom, affording structures F (transoid) and form G
(cisoid), respectively. Although many coordination modes
are possible for keto ylides [17], coordination through car-
bon is more predominant and observed with soft metal
ions, e.g., Pd(II), Pt(II), Ag(I), Hg(II), Au(I) and Au(III)
[8,18–21], whereas, O-coordination dominates when the
metals involved are hard, e.g., Ti(IV), Zr(IV), and Hf(IV)
[22]. Only W(0) complexes of the type W(CO)5L
(L = ylide) [23] and Pd(II) complexes of stoichiometry
[Pd(C6F5)(L2)(APPY)](ClO4) [18] [APPY = Ph3PCH-
COMe; L = PPh3 and PBu3; L2 = bipy] contain stable
ylides O-linked to a soft metal centre.
The goals of this report are (i) to present a method for
synthesis of mononuclear mercury(II) complexes of phos-
phorus ylides; (ii) to expand the knowledge in this field
via synthesis, characterization and theoretical studies of
new binuclear and mononuclear complexes. We believe
that bridge-splitting reaction can be initiated for binuclear
complexes by strong ligands leading to mononuclear
products.
2.3. Theoretical studies
The geometries of compounds were fully optimized
at the Hartree–Fock (HF) level of theory using the
GAUSSIAN98 program [30] on a Pentium-PC computer with
3600 MHz processor. The standard LanL2mb basis set was
used for all complexes [31]. This basis set includes effective
core potentials (ECP) for both the mercury and phospho-
rus atoms as well as halide (Cl, Br and 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 imagi-
nary frequency. Atomic coordinates for ab initio calcula-
tions were obtained from the data of the X-ray crystal
structure analyses.
2. Experimental
2.1. Physical measurements and materials
2.4. Sample preparation
All reactions were performed in air. Starting materials
were purchased from commercial sources and used without
further purification. The ligands were synthesized by the
reaction of related phosphine with 2-bromo-40-chloroaceto-
phenone and 2-bromo-40-nitroacetophenone and concomi-
tant elimination of HBr by NaOH [24]. Melting points
were measured on a SMPI apparatus. Elemental analysis
for C, H and N atoms were performed using a Perkin–
Elmer 2400 series analyzer. IR spectra were recorded on
a Shimadzu 435-U-04 FT spectrophotometer from KBr
2.4.1. Preparation of Ph3PCHCOC6H4NO2 (Y0), general
procedure for ylides [32]
Triphenylphosphine (0.262 g, 1 mmol) and 2-bromo
40-nitroacetophenone (0.243 g, 1 mmol) react in acetone
as solvent to produce the related phosphonium salt. Fur-
ther treatment with aqueous NaOH solution led to elimina-
tion of HBr, giving the free ligand Y0. IR (KBr disk): m
(cmꢁ1) 1529 (C@O), 884 (P–C). 1H NMR (CDCl3): d
2
(ppm) 4.51 (1H, d, JPH = 22.9 Hz, CH); 7.53–8.24 (19H,
m, Ph). 31P NMR (CDCl3): d (ppm) 14.19. 13C NMR
1
pellets. H, 13C and 31P NMR spectra were recorded on a
1
(CDCl3): d (ppm) 53.40 (d, JPC = 110.2 Hz, CH) 122.89–
300 MHz Bruker spectrometer in DMSO-d6 or CDCl3 as
solvent at 25 °C. Chemical shifts (ppm) are reported
148.11 (Ph); 181.79 (s, CO).

S.J. Sabounchei et al. / Journal of Organometallic Chemistry 693 (2008) 1975–1985
1977
2.4.2. (p-tolyl)3PCHCOC6H4Cl (Y00) [33]
I
I
C6H4Cl
1
IR (KBr, disk): m (cmꢁ1) 1581 (C@O), 882 (P–C). H
Hg
r t
NMR (CDCl3) dH: 2.39 (s, 9H, 3CH3); 4.34 (d,
2JPH = 23.12 Hz, 1H, CH); 7.31–8.34 (m, 16H, Ph). 31P
NMR (CDCl3) dP: 13.15 (s). 13C NMR (CDCl3) dC:
O
O
[(p-tolyl)3PCHC(O)C6H4Cl.HgI2]2 + 2 DMSO
CH
2
S
H3C
P(p-tolyl)3
(7)
1
CH3
20.95 (s, 3CH3); 51.19 (d, JPC = 112.1 Hz, CH); 123.33–
2
142.00 (Ph); 182.31 (d, JPC = 3.58 Hz, CO).
Scheme 2.
2.4.3. Synthesis of complexes
Binuclear complexes 1–6 were prepared based on a gen-
eral procedure as follows (Scheme 1). The crystals of the
complex 6 were obtained from the mother liquor methanol
solution. X-ray quality crystals of the complex 3 and 7
(Schemes 1 and 2) were grown from a dimethylsulfoxide
solution of compounds 3 and 6, respectively. This was car-
ried out by the slow evaporation of the solvent over several
days.
NMR (DMSO-d6): d (ppm) 20.99 (s). 13C NMR (DMSO-
1
d6): d (ppm) 49.81 (d, JPC = 78.2 Hz, CH); 122.92 (COPh
1
(m)); 123.82 (d, JPC = 89.8 Hz, PPh3 (i)); 128.96 (PPh3
3
(p)); 129.24 (d, JPC = 12.6 Hz, PPh3 (m)); 133.03 (d,
2JPC = 9.8 Hz, PPh3 (o)); 133.25 (COPh (o)); 144.11 (d,
3JPC = 4.7 Hz, COPh (i)); 148.78 (COPh (p)); 186.13 (s,
CO).
2.4.3.1. Synthesis of [(Y0) ꢀ HgCl2]2 (1), general procedure
for dimeric structures. To a methanolic solution (15 ml) of
HgCl2 (0.082 g, 0.3 mmol) was added a methanolic solu-
tion (10 ml) of Y0 (0.128 g, 0.3 mmol). The mixture was
stirred for 1 h. The separated solid was filtered and washed
with diethyl ether. Anal. Calc. for C52H40Cl4Hg2N2O6P2:
C, 44.81; H, 2.89; N, 2.01. Found: C, 44.48; H, 2.86; N,
2.11%. Yield 0.163 g, 78%. M.p. 219–220 °C. IR (KBr
disk): m (cmꢁ1) 1639 (C@O), 1602, 1519, 1484, 1438,
1346, 1310, 1292, 1190, 1108, 1028, 1008, 998, 858 (P–C)
and 827. 1H NMR (DMSO-d6): d (ppm) 5.36 (1H, d,
2JPH = 10.6 Hz, CH); 7.67–8.25 (19H, m, Ph). 31P NMR
(DMSO-d6): d (ppm) 21.01 (s). 13C NMR (DMSO-d6): d
2.4.3.3. [(Y0) ꢀ HgI2]2 (3). Anal. Calc. for C52H40Hg2I4-
N2O6P2: C, 35.49; H, 2.29; N, 1.59. Found: C, 35.87; H,
2.31; N, 1.59%. Yield 0.201 g, 76%. M.p. 206–207 °C. IR
(KBr disk): m (cmꢁ1) 1628 (C@O), 1595, 1520, 1481,
1435, 1347, 1316, 1290, 1191, 1107, 1035, 1011, 998, 879,
1
855 (P–C) and 809. H NMR (DMSO-d6): d (ppm) 5.11
2
(1H, d, JPH = 15.5 Hz, CH); 7.65–8.22 (19H, m, Ph). 31P
NMR (DMSO-d6): d (ppm) 18.91 (s). 13C NMR (DMSO-
1
d6): d (ppm) 50.72 (d, JPC = 92.9 Hz, CH); 122.80 (COPh
1
(m)); 124.39 (d, JPC = 90.2 Hz, PPh3 (i)); 128.41 (PPh3
3
(p)); 129.04 (d, JPC = 12.4 Hz, PPh3 (m)); 132.85 (COPh
2
(o)); 133.85 (d, JPC = 10.1 Hz, PPh3 (o)); 144.81 (d,
3JPC = 13.0 Hz, COPh (i)); 148.35 (COPh (p)); 184.26 (s,
CO).
1
(ppm) 48.45 (d, JPC = 81.0 Hz, CH); 123.05 (COPh (m));
1
123.24 (d, JPC = 89.8 Hz, PPh3 (i)); 129.16 (PPh3 (p));
3
129.43 (d, JPC = 12.1 Hz, PPh3 (m)); 133.24 (d,
2.4.3.4. [(Y00) ꢀ HgCl2]2 (4). Anal. Calc. for C58H52Cl6-
Hg2O2P2: C, 47.82; H, 3.60. Found: C, 47.65; H, 3.58%.
Yield 0.148 g, 68%. M.p. 179–182 °C. IR (KBr disk): m
(cmꢁ1) 1642 (C@O), 1598, 1587, 1569, 1499, 1399, 1312,
1288, 1188, 1110, 1089, 1023, 1006, 821 (P–C) and 805.
1H NMR (DMSO-d6) dH: 2.45 (s, 9H, 3CH3); 5.24 (br,
1H, CH); 7.38–8.12 (m, 16H, Ph). 31P NMR (DMSO-d6)
dP: 21.36 (s). 13C NMR (DMSO-d6) dC: 21.59 (3CH3);
2JPC = 10.4 Hz, PPh3 (o)); 133.5 (COPh (o)); 142.90 (d,
3JPC = 9.6 Hz, COPh (i)); 149.14 (COPh (p)); 188.03 (s,
CO).
2.4.3.2. [(Y0) ꢀ HgBr2]2 (2). Anal. Calc. for C52H40Br4-
Hg2N2O6P2: C, 39.74; H, 2.57; N, 1.78. Found: C, 39.29;
H, 2.60; N, 1.74%. Yield 0.189 g, 80%. M.p. 226–227 °C.
IR (KBr disk): m (cmꢁ1) 1635 (C@O), 1599, 1522, 1482,
1434, 1347, 1317, 1289, 1193, 1106, 1034, 1011, 998, 885,
1
121.10 (d, JPC = 92.46 Hz, p-tolyl (i)); 128.46 (COPh
3
(m)); 130.44 (d, JPC = 11.70 Hz, p-tolyl (m)); 130.52 (p-
1
2
856 (P–C) and 811. H NMR (DMSO-d6): d (ppm) 5.39
tolyl (p)); 133.74 (d, JPC = 10.11 Hz, p-tolyl (o)); 137.08
2
(1H, d, JPH = 9.9 Hz, CH); 7.67–8.25 (19H, m, Ph). 31P
(COPh (p)); 137.08 (COPh (i)); 144.28 (COPh (o)); (CO,
was not seen or br).
2.4.3.5. [(Y00) ꢀ HgBr2]2 (5). Anal. Calc. for C58H52Br4-
Cl2Hg2O2P2: C, 42.62; H, 3.21. Found: C, 42.38; H, 2.93%.
Yield 0.174 g, 71%. M.p. 178–180 °C. IR (KBr disk): m
(cmꢁ1) 1624 (C@O), 1597, 1589, 1568, 1497, 1399, 1316,
1292, 1187, 1108, 1092, 1026, 1010, 824 (P–C), 808 and
PAr3
CH
X
O
X
CH3OH
r t, 1h
R
Ar3PCHC(O)R+ HgX2
Hg
Hg
R
X
O
X
CH
PAr3
(1): R = C6H4NO2, Ar = Ph, X = Cl
(2): R = C6H4NO2, Ar = Ph, X = Br
(3): R = C6H4NO2, Ar = Ph, X = I
(4): R = C6H4Cl, Ar = p-tolyl, X = Cl
(5): R = C6H4Cl, Ar = p-tolyl, X = Br
(6): R = C6H4Cl, Ar = p-tolyl, X = I
1
794. H NMR (CDCl3) dH: 2.42 (s, 9H, 3CH3); 5.32 (br,
1H, CH); 7.24–8.08 (m, 16H, Ph). 31P NMR (CDCl3) dP:
24.04 (s). 13C NMR (CDCl3) dC: 21.82 (3CH3); 119.08 (d,
1JPC = 92.53 Hz, p-tolyl (i)); 128.97 (COPh (m)); 130.57
3
Scheme 1.
(p-tolyl (p)); 130.64 (d, JPC = 11.34 Hz, p-tolyl (m));

1978
S.J. Sabounchei et al. / Journal of Organometallic Chemistry 693 (2008) 1975–1985
2
133.71 (d, JPC = 9.43 Hz, p-tolyl (o)); 134.52 (COPh (p));
139.53 (COPh (i)); 144.97 (COPh (o)); 192.10 (s, CO).
corresponding spectra. The proton decoupled 31P NMR
spectra show only one sharp singlet between 18.91 and
21.36 ppm in the complexes. The appearance of a single
signal for the PCH group in each of the 31P and 1H
NMR spectra indicates that all ligands are in the same
environment in these complexes, as expected for C-coordi-
nation. It must be noted that O-coordination of the ylide
generally leads to the formation of a mixture of cisoid
and transoid isomers, giving rise to two different signals
2.4.3.6. [(Y00) ꢀ HgI2]2 (6). Anal. Calc. for C58H52Cl2-
Hg2I4O2P2: C, 38.22; H, 2.88. Found: C, 37.79; H, 2.53%.
Yield 0.205 g, 75%. M.p. 180–182 °C. IR (KBr disk): m
(cmꢁ1) 1708, 1625 (C@O), 1598, 1588, 1498, 1399, 1318,
1293, 1189, 1110, 1090, 1038, 1010, 820 (P–C) and 804.
1H NMR (CDCl3) dH: 2.43 (s, 9H, 3CH3); 4.97 (br d,
2JPH = 7.62 Hz, 1H, CH); 7.34–7.97 (m, 16H, Ph). 31P
NMR (CDCl3) dP: 19.51 (s). 13C NMR (DMSO-d6) dC:
1
in 31P and H NMR spectra (Chart 1) [18]. The 31P nuclei
shielding of the complexes appeared to be lower by about
4.5–8 ppm with respect to the parent ylides also indicating
that coordination of the ylide has occurred [8,10–12,36].
Satellites due to coupling to 199Hg for ylidic complexes of
Hg(II) are only observed at low temperature [10,36] or by
solid-state 31P NMR [36] and also in the case of
Hg(NO3)2 ꢀ H2O as metal source [12]. Failure to observe
satellites in above spectra was previously noted in the ylide
1
21.14 (3CH3); 120.83 (d, JPC = 91.78 Hz, p-tolyl (i));
127.91 (COPh (m)); 129.55 (p-tolyl (p)); 129.83 (d,
3JPC = 12.89 Hz, p-tolyl (m)); 133.05 (d, JPC = 10.59 Hz,
2
p-tolyl (o)); 136.40 (COPh (p)); 136.93 (COPh (i)); 143.67
(COPh (o)); 187.44 (s, CO).
2.4.3.7. [(Y00) ꢀ HgI2 ꢀ DMSO] (7). 0.182 g (0.1 mmol)
of binuclear complex 6 was dissolved in DMSO (2 ml).
The pale yellow crystals formed by the slow evaporation
of the solvent over several days. Anal. Calc. for
C31H31ClHgI2O2PS: C, 37.67; H, 3.16. Found: C, 37.52;
H, 3.29%. Yield 0.186 g, 94%. Decomp. at 180 °C. IR
(KBr disk): m (cmꢁ1) 1621 (C@O), 1598, 1588, 1499,
1399, 1315, 1297, 1190, 1109, 1090, 1038, 1022, 1010, 827
(P–C) and 805. 1H NMR (DMSO-d6) dH: 2.54 (s, 9H,
Table 1
Crystallographic data summary for binuclear complexes 3 and 6
Compound
3
6
Empirical formula
Fw
C
52H40Hg2I4N2O6P2 C58H52Cl2Hg2I4O2P2
1759.58
293(2)
0.71073
Triclinic
1822.62
293(2)
0.71073
Monoclinic
P21/c
11.9610(6)
11.3248(7)
22.7971(11)
90
95.251(4)
90
Temperature (K)
˚
Wavelength (A)
2
3CH3); 5.07 (d, JPH = 10.75 Hz, 1H, CH); 7.43–8.03 (m,
Crystal system
Space group
16H, Ph). 31P NMR (DMSO-d6) dP: 19.82 (s). 13C NMR
ꢀ
P1
1
˚
(DMSO-d6) dC: 21.14 (3CH3); 120.83 (d, JPC = 91.78 Hz,
p-tolyl (i)); 127.91 (COPh (m)); 129.55 (p-tolyl (p));
a (A)
10.0285(15)
12.1560(18)
12.8738(18)
72.014(11)
68.762(11)
71.782(12)
1355.2(3)
1
˚
b (A)
˚
3
c (A)
129.83 (d, JPC = 12.89 Hz, p-tolyl (m)); 133.05 (d,
a (°)
b (°)
c (°)
2JPC = 10.59 Hz, p-tolyl (o)); 136.40 (COPh (p)); 136.93
(COPh (i)); 143.67 (COPh (o)); 187.44 (s, CO).
3
˚
Volume (A )
3075.0(3)
2
1.969
Z
3. Results and discussion
Dcalc (Mg/m3)
2.156
Absorption coefficient
8.043
7.171
3.1. Spectroscopy
(mmꢁ1
)
F(000)
Crystal size (mm)
h Range for data collection 1.81–26.79
(°)
10320
0.60 ꢂ 0.30 ꢂ 0.22
1704
The m (CO) band, which is sensitive to complexation, is
observed for complexes at higher frequencies compared to
the parent ylides, indicating coordination of the ylide thor-
ough carbon atom in each case [34]. The m (P+–Cꢁ) band,
which is also diagnostic of the coordination modes, occurs
at lower frequencies for complexes in comparison to the
parent ylides, consistent with some removal of electron
density in the P–C bonds [10–12]. C-coordination causes
an increase in m (CO) and decrease in m (P+–Cꢁ) while,
for O-coordination a lowering for both frequencies is
expected [21]. It should be noted that there is not any sig-
nificant difference in the IR absorption bands for binuclear
and related mononuclear complexes.
0.3 ꢂ 0.2 ꢂ 0.1
1.79–29.22
Limiting indices
ꢁ12 6 h 6 12,
ꢁ16 6 h 6 13,
ꢁ14 6 k 6 15,
ꢁ31 6 l 6 31
ꢁ15 6 k 6 15,
ꢁ15 6 l 6 15
Reflections collected/
10320/5263 (0.0410) 19645/8069 (0.0334)
unique (Rint
)
Completeness to h
Absorption correction
Maximum and minimum
transmission
26.79, 90.7%
Numerical
0.175 and 0.070
29.22, 96.6%
Numerical
0.485 and 0.195
Refinement method
Full-matrix least-
squares on F2
Full-matrix least-
squares on F2
8069/0/316
Data/restraints/parameters 5263/0/307
Goodness-of-fit on F2
Final R indices [I > 2r(I)]
1.125
1.137
1
In the H NMR spectra, the signals due to the methinic
R1 = 0.0411,
wR2 = 0.1067
R1 = 0.0435,
wR2 = 0.1086
2.065 and ꢁ2.060
R1 = 0.0479,
wR2 = 0.0827
R1 = 0.0706,
wR2 = 0.0894
1.312 and ꢁ1.070
protons for complexes are doublet or broad. Similar behav-
ior was observed earlier in the case of ylide complexes of
platinum(II) chloride [35]. The expected lower shielding
R indices (all data)
1
of 31P and H nuclei for the PCH group upon complexa-
Largest differencꢁe3in peak
˚
and hole (e A
)
tion in the case of C-coordination were observed in their

S.J. Sabounchei et al. / Journal of Organometallic Chemistry 693 (2008) 1975–1985
1979
complexes of Hg(II) [37] and Ag(I) [21] and was assigned to
fast exchange of the ylide with the metal at higher
temperatures.
comparable to analogous distances in (Ph3PCH-
COPh ꢀ HgI2)2 (2.312(13) and 2.705(1) A, respectively) [8].
˚
The angles subtended by the ligands at the Hg(II) centre
in 3 and 6 vary from 91.402(17) to 125.42(11) (3) and
87.261(14) to 123.80(14) (6) indicating a much distorted tet-
rahedral environment. The widening of the IHgC angle
from the tetrahedral angle must be due to the higher s char-
acter of the sp3 hybrid mercury orbitals involved in the
above bonds and the formation of a strong halide-bridge
between Hg atoms which requires the internal IHgI angles
91.402(17) (3) and 87.261(14) (6) to be considerably smal-
ler. The two mercury atoms and two bridging halides in
each case are perfectly coplanar. The internuclear distance
between mercury atoms in these complexes were found to
be 4.188 (3) and 4.0969 (6), that are much longer than
The most interesting aspect of the 13C NMR spectra of
the complexes is the higher shielding of the ylidic carbon
atoms. Such a higher shielding was observed in [PdCl(g3-
2-XC3H4)(C6H5)3PCHCOR] (X = H, CH3; R = CH3,
C6H5), and is due to the change in hybridization of the yli-
dic carbon atom on coordination [38]. Similar higher
shielding of 2–3 ppm with reference to the parent ylide were
also observed in the case of [(C6H5)3PC5H4HgI2]2 [37]. The
lower shielding of the carbonyl C atom in the complexes
compared to the same carbon atom in the parent ylides
was also observed.
˚
3.2. X-ray crystallography
the sum of van der Waals radii (1.5 A) of the two mercury
atoms [39], indicating the absence of significant bonding
interactions between the mercury atoms in the molecular
structures.
Table 3 provides the crystallographic results and refine-
ment information for complex 7. The molecular structure is
shown in Fig. 3. Pertinent bond distances and angles for 7
are given in Table 4. Packing diagrams, fractional atomic
coordinates and equivalent isotropic displacement coeffi-
cients (Ueq) for the non-hydrogen atoms are shown in Sup-
plementary material.
Table 1 provides the crystallographic results and refine-
ment information for complexes 3 and 6. The molecular
structures are shown in Figs. 1 and 2. Pertinent bond dis-
tances and angles for 3 and 6 are given in Table 2. Packing
diagrams, fractional atomic coordinates and equivalent iso-
tropic displacement coefficients (Ueq) for the non-hydrogen
atoms of the complexes are shown in Supplementary
material.
The Hg(II) centre in complexes 3 and 6 is four-coordi-
nate with sp3 hybridization. This environment involves
one short terminal Hg–I bond, one Hg–C bond and two
asymmetric bridging Hg–I bonds. The Hg–C and terminal
The Hg(II) centre in complex 7 is coordinated by one
carbon, one oxygen and two iodine atoms in a distorted
tetrahedral geometry. The two different Hg–I distances in
˚
˚
Hg–I bond lengths in 3, (2.292(5) and 2.6846(7) A, respec-
7 (2.6701(5) and 2.7102(5) A) are less than those of found
˚
tively) and in 6 (2.310(6) and 2.6999(6) A, respectively) are
in mononuclear complex of [HgI2(PPh3)2] (2.733(1) and
Fig. 1. ORTEP view of X-ray crystal structure of [(Y0) ꢀ HgI2]2 (3).

1980
S.J. Sabounchei et al. / Journal of Organometallic Chemistry 693 (2008) 1975–1985
Fig. 2. ORTEP view of X-ray crystal structure of [(Y00) ꢀ HgI2]2 (6).
Table 2
involved in the above bonds and the steric effects of phos-
phine group causing the CHgI angle to be larger.
The stabilized resonance structure for the parent ylides
is destroyed by the complex formation, thus, the C(H)–C
˚
Selected bond lengths (A) and angles (°) for 3 and 6
3
6
Bond lengths
C(H)–C
C(H)–P
C(H)–Hg
C–O
I(1)–Hg(1)
I(2)–Hg(1)
I(2)–Hg(1a)
˚
˚
˚
1.475(7)
1.793(4)
2.292(5)
1.220(7)
2.6846(7)
2.7900(6)
3.1924(6)
1.488(7)
1.774(6)
2.310(6)
1.225(6)
2.6999(6)
2.7902(5)
3.1362(5)
bond lengths 1.475(7) A (3), 1.488(7) A (6) and 1.478(7) A
(7) are significantly longer than the corresponding dis-
tances found in the similar uncomplexed phosphoranes
˚
˚
(1.407(8) A [42] and 1.401(2) A [43]). On the other hand,
the bond length of P–C(H) in the similar ylide is
1.7194(17) A [43] which shows that the corresponding
bonds are considerably elongated to 1.793(4) A (3),
1.774(6) A (6) and 1.785(5) A (7). The Hg–I(1), Hg–I(2)
˚
˚
Bond angles
C(O)–C(H)–Hg
P–C(1)–Hg
Hg(1)–I(2)–Hg(1a)
C(H)–Hg–I(1)
C(H)–Hg–I(2)
I(1)–Hg–I(2)
C(1)–Hg(1)–I(2a)
I(1)–Hg(1)–I(2a)
I(2)–Hg(1)–I(2a)
˚
˚
105.5(3)
111.5(2)
101.6(4)
112.0(3)
˚
and Hg–C bond lengths in 7 (2.6701, 2.71 and 2.261 A,
88.598(17)
125.42(11)
116.89(11)
114.00(2)
95.78(12)
101.47(2)
91.402(17)
92.739(14)
114.25(13)
123.80(14)
114.54(2)
96.26(15)
114.89(2)
87.261(14)
respectively) are shorter than those of found in the parent
˚
binuclear complex 6 (2.6999, 2.79 and 2.310 A, respec-
tively) indicating relatively strong bonds in mononuclear
complexes compared to binuclears.
The C-coordination of the title ylides is in contrast to
the O-coordination of the phosphorus ylide Ph3PC(CO-
Me)(COPh) (ABPPY) in a different Hg(II) complex [44].
The difference in coordination mode between ABPPY
and these ylides to Hg(II) can be rationalized in terms of
the electronic properties and steric requirements of the
ylides. The lower electronic density at the ylidic C atom
in doubly stabilized ylides compared to simple stabilized
ylides has been calculated by DFT (density functional the-
ory) methods recently [45]. It was also demonstrated in the
same paper that these factors are not solely responsible for
the bonding properties of doubly stabilized ylides. For
‘‘simple” stabilized ylides, the C- vs. O-bonding is also a
very delicate balance of steric and electronic properties
˚
2.763(1) A) [40], indicating relatively strong Hg–I bonds in
7. Above distances are comparable to 2.693(2) and
2.727(2) A found in [HgI2{Ph2P(S)CH2PPh2}] [41] and ter-
minal Hg–I distance of 2.6999(6) A noted for dimeric com-
plex 6. The difference between two distances in these
complexes might be arising from steric effects of the large
ylidic groups. The angles around mercury vary from
85.00(15) to 120.87(12), indicating a much distorted tetra-
hedral environment. This distortion must be due to the
higher s character of the sp3 hybrid mercury orbitals
˚
˚

S.J. Sabounchei et al. / Journal of Organometallic Chemistry 693 (2008) 1975–1985
1981
Table 3
Crystallographic data summary for mononuclear complex 7
Compound
7
Empirical formula
Fw
C31H32ClHgI2O2PS
989.44
Temperature (K)
Wavelength (A)
150(2)
0.71073
˚
Crystal system
Space group
a (A)
Monoclinic
P2(1)/n
11.4861(6)
˚
˚
b (A)
14.1632(7)
˚
c (A)
20.9956(11)
90
104.233(3)
90
3310.7(3)
a (°)
b (°)
c (°)
3
˚
Volume (A )
Z
4
Dcalc (Mg/m3)
1.985
6.732
1872
Absorption coefficient (mmꢁ1
F(000)
)
Crystal size (mm)
h Range for data collection (°)
Limiting indices
0.32 ꢂ 0.21 ꢂ 0.14
1.75–27.50
ꢁ14 6 h 6 14,
ꢁ18 6 k 6 18,
ꢁ27 6 l 6 27
105375
Fig. 3. ORTEP view of X-ray crystal structure of [(Y00) ꢀ HgI2 ꢀ DMSO]
(7).
Reflections collected
Independent reflections (Rint
Completeness to h = 25.00°
Absorption correction
)
7601 (0.0375)
100.0%
Semi-empirical from
equivalents
0.4525 and 0.2219
Full-matrix least-squares on
F2
Table 4
Maximum and minimum transmission
Refinement method
˚
Selected bond lengths (A) and angles (°) for 7
7
Data/restraints/parameters
Goodness-of-fit on F2
Final R indices [I > 2r(I)]
R indices (all data)
7601/236/357
1.098
R1 = 0.0351, wR2 = 0.1016
R1 = 0.0397, wR2 = 0.1068
1.872 and ꢁ3.022
Bond lengths
Hg(1)–C(1)
Hg(1)–I(1)
Hg(1)–I(2)
Hg(1)–O(1S)
P(1)–C(1)
O(1)–C(23)
C(1)–C(23)
S(2)–O(1S)
2.261(5)
2.6701(5)
2.7102(5)
2.621(4)
1.785(5)
1.221(6)
1.478(7)
1.515(4)
Largest difference in peak and hole
ꢁ3
˚
(e A
)
Bond angles
[46]. In this balance it is necessary to consider not only the
size and shape of the ligand in the final bonding mode, but
also the electronic nature of the metal (Pd, Pt, Ru, Au, etc.)
and the donor atoms (C, O, N, etc.) and even the position
of the coordination site (trans to a C atom, trans to a N
atom, trans to an O atom, and so on). All these facts must
be considered as a whole in order to account for the final
bonding mode of a given ylide. The nucleophilicity of the
carbanion in ABPPY is less than in our ylides; 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 influ-
ences on the coordination modes of ylide molecules to
Pt(II) systems [47]. These authors concluded that the pre-
ferred coordination mode is via the ylidic carbon, but that
steric hindrance around the metal centre or the ylidic car-
bon will necessitate O-coordination. Indeed, this trend is
reflected here, these ylides are slightly less sterically
demanding than ABPPY and are C-coordinated to Hg(II).
I(2)–Hg(1)–I(1)
C(1)–Hg(1)–I(2)
C(1)–Hg(1)–I(1)
C(1)–Hg(1)–O(1S)
O(1S)–Hg(1)–I(2)
O(1S)–Hg(1)–I(1)
C(23)–C(1)–P(1)
C(23)–C(1)–Hg(1)
P(1)–C(1)–Hg(1)
117.063(19)
120.87(12)
119.64(12)
85.00(15)
102.69(10)
97.99(10)
114.2(3)
106.8(3)
109.8(2)
3.3. DMSO as ligand
Literature data show that the coordination mode of
dimethylsulfoxide (DMSO) to relatively soft metal atoms
depends on both electronic and steric factors deriving from
the DMSO moderate p-acceptor properties and its greater
steric demand, in the case of S-bonding [48]. In the case of
ruthenium(II) complexes, coordination through sulfur
(DMSO–S) seems to be preferred over coordination
through oxygen (DMSO–O) to get stable species, unless

1982
S.J. Sabounchei et al. / Journal of Organometallic Chemistry 693 (2008) 1975–1985
˚
ligand overcrowding occurs [49] or DMSO is trans to
strong p-acceptors like CO [50] and NO [51,52]. Although
on the basis of the Hard-Soft-Acid-Base principle, S-bond-
ing is preferred by ‘soft’ metal ions but with bulky ligands
like present phosphorus ylides, steric effects can induce O-
bonding. It may also be seen that for ‘soft’ metal ions, such
as Ag(I), Cd(II), and Hg(II), there is evidence of a preva-
lence of O-bonded species, even in the absence of p-accept-
ing or bulky ligands. This suggests that a particular
electronic structure is required in order to favor the
metal–sulfur bond over the metal–oxygen one [48]. Bulki-
ness of present ylides and the absence of above influences
in the structure shown in Fig. 3 lead to preferring of O-
bonding. An overestimate is found for the calculated S–O
comparison between the calculated bond lengths (A) and
bond angles (°) with corresponding experimental values
for compound 3 is presented in Table 5. A list of calculated
key bond lengths and bond angles and the optimized struc-
tures of compounds 1 and 2 are presented in Supplemen-
tary material.
The calculated structure of 3 in the gas-phase agrees well
with the structure observed by X-ray crystallography,
although the calculated bond lengths are slightly longer
than measured ones. We then changed the geometrical
structure of compound 3 by replacement of position of
one terminal halide atom with one coordinated ylide group
˚
˚
distance in ‘free’ DMSO (1.509 A), which results 0.018 A
longer than the experimental reference value of
Table 5
˚
A comparison between the calculated bond lengths (A) and bond angles
˚
(°) with corresponding experimental values for compound 3
1.492(1) A [53]. The significant elongation of the S–O dis-
[(Y0) ꢀ HgI2]2 (3)
X-ray
HF/Lanl2mb
tance upon O-coordination is further confirmed by the
recent X-ray structure determination of a disulfoxide and
related copper(II) complexes, where the average S–O dis-
Bond lengths
I(2)–Hg(1)
I(1)–Hg(1)
I(2a)–Hg(1)
P(1)–C(15)
P(1)–C(8)
C(9)–P(1)
C(21)–P(1)
Hg(1)–C(8)
3.192(6)
2.685(7)
2.790(6)
1.805(5)
1.793(4)
1.805(5)
1.804(5)
2.292(5)
3.217
2.964
3.172
1.918
1.976
1.932
1.929
2.263
˚
˚
tances are of 1.487(4) A (free) and 1.520(3) A (O-bonded)
[54]. It is worth noting that in 7 the S–O bond distance
˚
˚
˚
of 1.515(4) A, is about 0.023 A longer than the experimen-
tal reference value of 1.492(1) A for free DMSO ligand [53].
3.4. Theoretical studies
Bond angles
Hg(1)–I(2)–Hg(1a)
I(2)–Hg(1)–I(2a)
I(2a)–Hg(1)–I(1)
I(2)–Hg(1)–C(8)
I(2)–Hg(1)–I(1)
I(2a)–Hg(1)–C(8)
I(1)–Hg(1)–C(8)
O(3)–C(7)–C(6)
O(3)–C(7)–C(8)
Hg(1)–C(8)–P(1)
88.599
91.401
101.467
95.797
114.000
116.881
125.427
119.502
122.024
111.494
89.315
90.683
We were interested to (i) determine the amount of the
energy difference between the observed trans-like structures
and the alternative possible cis-like isomers; (ii) determine
whether the formation of mononuclear complexes in the
gas-phase in which DMSO acts as ligand, energetically
are more favorable than those of binuclear complexes.
The observed geometry of compound 3 was used as a
basis of ab initio calculations for compounds 1–3. The opti-
mized cis and trans structures of 3 are shown in Fig. 4. A
107.523
107.475
104.439
109.253
130.200
120.823
120.919
111.892
Fig. 4. Calculated molecular structures of (a) trans-[(Y0) ꢀ HgI2]2 and (b) cis-[(Y0) ꢀ HgI2]2.

S.J. Sabounchei et al. / Journal of Organometallic Chemistry 693 (2008) 1975–1985
1983
Table 6
A comparison between energies of cis- and trans-like isomers for compounds 1–3
Compound
Cis (hartree)
Trans (hartree)
DE (kcal molꢁ1 a
)
1
2
3
[(Y0) ꢀ HgCl2]2
[(Y0) ꢀ HgBr2]2
[(Y0) ꢀ HgI2]2
ꢁ2672.5879487
ꢁ2665.5202294
ꢁ2658.4301041
ꢁ2672.6077282
ꢁ2665.5266673
ꢁ2658.436498
12.41
4.04
4.01
a
The energy of cis-like isomer relative to trans-like isomer.
Table 7
to obtain cis-like isomers which were used as the basis for
additional calculations. The minimization of these isomers
at the same level of theory gave the desired cis-like isomers
for complexes 1–3. As can be seen in Table 6 the latter cis-
like isomers are about 4–12 kcal/mol less stable than trans-
like structures. It is clear therefore that the dimeric struc-
ture with the general formula [Ylide ꢀ HgX2]2 may occur
as either the observed trans-like isomer or the alternative
higher-energy cis-like isomer.
˚
A comparison between the calculated bond lengths (A) and bond angles
(°) for compound [(Y00) ꢀ HgI2 ꢀ DMSO] (7) with corresponding experi-
mental values
[(Y00) ꢀ HgI2 ꢀ DMSO](7)
Bond lengths
X-ray
HF/Lanl2mb
Hg(9)–I(8)
Hg(9)–I(4)
2.710
3.069
3.028
2.283
2.309
1.917
1.932
1.924
1.965
2.670
2.261
2.621
1.803
1.789
1.797
1.784
Hg(9)–C(18)
Hg(9)–O(64)
P(20)–C(10)
P(20)–C(24)
P(20)–C(27)
P(20)–C(18)
It is interesting that when the ylide is bulky such as Y0,
the relative energy of cis- and trans-like isomers signifi-
cantly depends on the size of the bridging halide. Note that
the cis-like isomer in the case of compounds 2 and 3 is only
about 4 kcal less stable than the trans-like isomer, but in
the case of compound 1 the cis-like isomer is more than
12 kcal less stable than trans-like isomer (Table 6).
In the trans-like structures of compounds 1–3, the inter-
nuclear distances between mercury atoms were calculated
Bond angles
I(4)–Hg(9)–I(8)
117.066
120.882
102.683
119.633
97.991
120.444
121.345
113.827
107.439
109.304
111.953
106.801
107.320
109.792
114.128
119.012
99.468
I(4)–Hg(9)–C(18)
I(4)–Hg(9)–O(64)
I(8)–Hg(9)–C(18)
I(8)–Hg(9)–O(64)
O(7)–C(14)–C(15)
O(7)–C(14)–C(18)
C(10)–P(20)–C(18)
C(10)–P(20)–C(24)
C(10)–P(20)–C(27)
C(18)–P(20)–C(24)
C(18)–P(20)–C(27)
C(24)–P(20)–C(27)
Hg(9)–C(18)–P(20)
119.012
102.462
120.734
122.713
110.479
109.639
109.926
111.299
110.191
105.179
113.010
˚
to be 4.11, 4.28 and 4.49 A, respectively, indicating the
absence of significant bonding interactions between the
mercury atoms. These distances are also increased by
increasing the size of the bridging halides (Cl, Br and I).
The analytical and spectroscopic data for compound 7
can be similar to those of the other complexes synthesized
here containing ylide Y00. Thus the observed geometry of
compound 7 was considered for ab initio calculations.
The optimized structure of compound 7 is shown in
Fig. 5. A comparison between the calculated bond lengths
list of calculated key bond lengths and bond angles and
the optimized structures of compounds [(Y00) ꢀ HgX2 ꢀ
DMSO] (where X = Cl and Br) are presented in Supple-
mentary material.
˚
(A) and bond angles (°) for these compounds with corre-
sponding experimental values are presented in Table 7. A
As can be seen, the calculated bond lengths are slightly
longer than measured ones but the similarity of calculated
and measured bond angles reflects the similar geometrical
structures for these compounds in both the solid-state
and gas-phase. The results of calculations (Table 8) show
that the products of the following proposed reaction (Eq.
(1)) are more stable than reactants. These stabilities are
about 29, 34 and 40 kcal/mol where X is Cl, Br and I,
respectively.
rt
½ðY00Þ ꢀ HgX2ꢃ2 þ 2DMSO ! 2½ðY00Þ ꢀ HgX2 ꢀ DMSOꢃ
ð1Þ
The similarity of calculated energies for latter reaction indi-
cates that the reaction energy mainly depends on the bridg-
ing halide atom. Therefore it is clear that for all
compounds synthesized here, the gas-phase reaction shown
in Eq. (1) is an exothermic reaction, thus it seems that, the
bridge-splitting reaction in DMSO solution is potentially
Fig. 5. Calculated molecular structure of [(Y00) ꢀ HgI2 ꢀ DMSO].

1984
S.J. Sabounchei et al. / Journal of Organometallic Chemistry 693 (2008) 1975–1985
Table 8
Calculated electronic energies for binuclear complexes, DMSO and mononuclear complexes involved in Eq. (1)
Compounds
[(Y00) ꢀ HgX2]2 (hartree)
DMSO (hartree)
[(Y00) ꢀ HgX2 ꢀ DMSO] (hartree)
DE (kcal molꢁ1
)
X = Cl
X = Br
X = I
ꢁ2530.9594524
ꢁ2523.8733023
ꢁ2516.7904538
ꢁ161.8305649
ꢁ161.8305649
ꢁ161.8305649
ꢁ1427.3332829
ꢁ1423.7940979
ꢁ1420.2577546
28.86
33.74
40.11
[4] H.J. Christau, Chem. Rev. 94 (1994) 1299.
[5] O.I. Kolodiazhnyi, Tetrahedron 52 (1996) 1855.
[6] N.A. Nesmeyanov, V.M. Novikov, Q.A. Reutov, J. Organomet.
Chem. 4 (1965) 202.
[7] E.T. Weleski, J.L. Silver, M.D. Jansson, J.L. Burmeister, J. Organo-
met. Chem. 102 (1975) 365.
possible for all dimeric complexes in which DMSO acts as
a ligand. The data show that in the case of iodine complex,
the formation of mononuclear complexes is relatively more
favorable than corresponding chlorine and bromine com-
plexes (Table 8).
[8] M. Kalyanasundari, K. Panchanatheswaran, W.T. Robinson, H.
Wen, J. Organomet. Chem. 491 (1995) 103.
[9] R. Sanehi, R.K. Bansal, R.C. Mehrotra, Indian J. Chem. 24a, N12
(1985) 1031.
4. Conclusions
Present study describes the synthesis and characteriza-
tion of a series of binuclear and mononuclear Hg(II) com-
plexes of phosphorus ylides. On the basis of the physico-
chemical and spectroscopic data we propose that ligands
herein exhibit monodentate C-coordination to the metal
centre, which is further confirmed by the X-ray crystal
structure of the complexes. This study also presents a
method for synthesis of mononuclear Hg(II) complexes
of phosphorus ylides via bridge-splitting reaction using
some of ligands like DMSO. Theoretical studies on the
gas-phase structure of the complexes, confirm that, the
bridge-splitting reaction in DMSO solution is potentially
possible for dimeric complexes in which DMSO acts as a
ligand.
[10] S.J. Sabounchei, A. Dadrass, M. Jafarzadeh, S. Salehzadeh, H.R.
Khavasi, J. Organomet. Chem. 692 (2007) 2500.
[11] S.J. Sabounchei, V. Jodaian, H.R. Khavasi, Polyhedron 26 (2007)
2845.
[12] S.J. Sabounchei, H. Nemattalab, H.R. Khavasi, J. Organomet.
Chem. 692 (2007) 5440.
[13] J. Vicente, M.T. Chicote, J.A. Cayuelas, J. Fernandez-Baeza, P.G.
Jones, G.M. Sheldrick, P. Espinet, J. Chem. Soc., Dalton Trans.
(1985) 1163.
[14] L.R. Falvello, S. Fernandez, R. Navarro, I. Pascual, E.P. Urriola-
beitia, J. Chem. Soc., Dalton Trans. (1997) 763.
´
[15] J. Vicente, M.T. Chicote, J. Fernandez-Baeza, J. Organomet. Chem.
364 (1989) 407.
[16] L.R. Falvello, S. Fernandez, R. Navarro, E.P. Urriolabeitia, Inorg.
Chem. 35 (1996) 3064.
[17] J.A. Albanese, A.L. Rheingold, J.L. Burmeister, Inorg. Chim. Acta
150 (1988) 213.
´
´
´
[18] R. Uson, J. Fornies, R. Navarro, P. Espinet, C. Mendıvil, J.
Acknowledgements
Organomet. Chem. 290 (1985) 125.
[19] J. Vicente, M.T. Chicote, I. Saura-Llamas, J. Turpin, J. Fernandez-
Baeza, J. Organomet. Chem. 333 (1987) 129.
[20] J. Vicente, M.T. Chicote, J. Fernandez-Baeza, J. Martin, I. Saura-
Llamas, J. Turpin, P.G. Jones, J. Organomet. Chem. 331 (1987) 409.
[21] H. Koezuka, G. Matsubayashi, T. Tanaka, Inorg. Chem. 25 (1976)
417.
We are grateful to the Bu-Ali Sina University for a grant
and Mr. Zebarjadian for recording the NMR spectra. The
authors thank Prof. Michael D. Ward (Department of
Chemistry, University of Sheffield, Sheffield S3 7HF,
UK) for his invaluable support in one of X-ray
experiments.
[22] J.A. Albanese, D.L. Staley, A.L. Rheingold, J.L. Burmeister, Inorg.
Chem. 29 (1990) 2209.
[23] I. Kawafune, G.E. Matsubayashi, Inorg. Chim. Acta 70 (1983) 1.
[24] F. Ramirez, S. Dershowitz, J. Org. Chem. 22 (1957) 41.
[25] Stoe & Cie, X-AREA, Version 1.30: Program for the Acquisition and
Analysis of Data, Stoe & Cie GmbH, Darmatadt, Germany, 2005.
[26] G.M. Sheldrick, SHELX97. Program for Crystal Structure Solution and
Refinement, University of Go¨ttingen, Germany, 1997.
[27] Stoe & Cie, X-STEP32, Version 1.07b: Crystallographic Package, Stoe
& Cie GmbH, Darmstadt, Germany, 2000.
[28] G.M. Sheldrick, SHELXS-97, a Program for Automatic Solution of
Crystal Structures, University of Go¨ttingen, Germany, 1997.
[29] G.M. Sheldrick, SHELX-97, A Program for Crystal Structure Refine-
ment, University of Go¨ttingen, Germany, 1997.
Appendix A. Supplementary material
CCDC 648211, 663328 and 648218 contain the supple-
mentary crystallographic data for complexes 3, 6 and 7.
These data can be obtained free of charge from The Cam-
bridge Crystallographic Data Centre via http://
www.ccdc.cam.ac.uk/data_request/cif.
data associated with this article can be found, in the online
version, at doi:10.1016/j.jorganchem.2008.02.025.
Supplementary
[30] M.J. Frisch, G.W. Trucks, H.B. Schlegel, G.E. Scuseria, M.A. Robb,
J.R. Cheeseman, V.G. Zakrzewski, J.A. Montgomery, R.E. Stratman,
J.C. Burant, S. Dapprich, J.M. Millam, A.D. Daniels, K.N. Kudin,
M.C. Strain, O. Farkas, J. Tomasi, V. Barone, M. Cossi, R. Cammi,
B. Menucci, C. Pomelli, C. Adamo, S. Clifford, J. Ochterski, G.A.
Petersson, P.Y. Ayala, Q. Cui, K. Morokuma, D.K. Malick, A.D.
Rabuck, K. Raghavachari, J.B. Foresman, J. Ciolowski, J.V. Ortiz,
B.B. Stefanov, G. Liu, A. Liashenko, P. Piskorz, I. Komaromi, R.
Gomperts, R.L. Martin, D.J. Fox, T. Keith, M.A. Al-Laham, C.Y.
Peng, A. Nanayakkara, C. Gonzales, M. Challacombe, P.M.W. Gill,
References
[1] G. Wittig, Angew. Chem. 92 (1980) 671.
[2] G. Wagner, T.B. Pakhomova, N.A. Bokach, J.J.R. Frausto da Silva,
J. Vicente, A.J.L. Pombeiro, V.Y. Kukushkin, Inorg. Chem. 40
(2001) 1683.
[3] N.A. Bokach, V.Y. Kukushkin, M. Haukka, J. da Silva, A.J.L.
Pombeiro, Inorg. Chem. 42 (2003) 3602.

S.J. Sabounchei et al. / Journal of Organometallic Chemistry 693 (2008) 1975–1985
1985
B.G. Jonhson, W. Chen, M.W. Wong, J.L. Andres, M. Head-
Gordon, E.S. Repogle, J.A. Pople, GAUSSIAN 98, Revision A.6,
Gaussian Inc., Pittsburgh, PA, 1998.
[43] S.J. Sabounchei, A. Dadrass, M. Jafarzadeh, H.R. Khavasi, Acta
Crystallogr., Sect. E 63 (2007) o3160.
[44] P. Laavanya, U. Venkatasubramanian, K. Panchanatheswaran,
J.A.K. Bauer, Chem. Commun. (2001) 1660.
[31] J.B. Collins, P.V.R. Schleyer, J.S. Binkley, J.A. Pople, J. Chem. Phys.
64 (1976) 5142.
[32] H.J. Bestmann, B. Arnason, Chem. Ber. 95 (1962) 1513.
[33] S.J. Sabounchei, H. Nemattalab, V. Jodaian, J. Chin. Chem. Soc. 55
(1) (2008).
´
´
´
[45] L.R. Falvello, J.C. Gines, J.J. Carbo, A. Lledos, R. Navarro, T.
Soler, E.P. Urriolabeitia, Inorg. Chem. 45 (2006) 6803.
[46] R. Navarro, E.P. Urriolabeitia, J. Chem. Soc., Dalton Trans. (1999)
4111.
[34] J. Vicente, M.T. Chicote, M.C. Lagunas, P.G. Jones, J. Chem. Soc.,
Dalton Trans. (1991) 2579.
[47] U. Belluco, R.A. Michelin, R. Bertani, G. Facchin, G. Pace, L.
Zanotto, M. Mozzon, M. Furlan, E. Zangrando, Inorg. Chim. Acta
252 (1996) 355.
[48] M. Calligaris, O. Carugo, Coord. Chem. Rev. 153 (1996) 83.
[49] E. Alessio, G. Mestroni, G. Nardin, W.M. Attia, M. Calligaris, G.
Sava, S. Zorzet, Inorg. Chem. 27 (1988) 4099.
[50] E. Alessio, B. Milani, M. Bolle, G. Mestroni, P. Faleschini, F.
Todone, S. Geremia, M. Calligaris, Inorg. Chem. 34 (1995)
4722.
[35] J.A. Teagle, J.L. Burmeister, Inorg. Chim. Acta 118 (1986) 65.
[36] E.C. Spencer, M.B. Mariyatra, J.A.K. Howard, A.M. Kenwright, K.
Panchanatheswaran, J. Organomet. Chem. 692 (2007) 1081.
[37] N.L. Holy, N.C. Baenziger, R.M. Flynn, D.C. Swenson, J. Am.
Chem. Soc. 98 (1976) 7823.
[38] G. Facchin, R. Bertani, M. Calligaris, G. Nardin, M. Mari, J. Chem.
Soc., Dalton Trans. (1987) 1381.
[39] J.E. Huheey, Inorganic Chemistry – Principles of Structure and
Reactivity, 2nd ed., Harper Int. Ed., New York, 1978, p. 233.
[40] L. Fa¨lth, Chem. Scripta 9 (1976) 71.
[41] T.S. Lobana, M.K. Sandhu, J. Chem. Soc., Dalton Trans. (1990)
691.
[51] B. Serli, E. Zangrando, E. Iengo, G. Mestroni, L. Yellowlees, E.
Alessio, Inorg. Chem. 41 (2002) 4033.
[52] B. Serli, E. Zangrando, E. Iengo, E. Alessio, Inorg. Chim. Acta 339
(2002) 265.
[53] M. Calligaris, N.S. Panina, J. Mol. Struct. 646 (2003) 61.
[54] M. Calligaris, A. Melchior, S. Geremia, Inorg. Chim. Acta 323 (2001)
89.
[42] M. Kalyanasundari, K. Panchanatheswaran, V. Parthasarathi, W.T.
Robinson, H. Wen, Acta Crystallogr. 50 (1994) 1738.