S.J. Sabounchei et al. / Inorganica Chimica Acta 362 (2009) 105–112
107
(ppm) 2.22 (3H, s, COCH3); 2.41 (9H, s, CH3); 4.76 (1H, br, CH);
3.1. Spectroscopy
7.47–7.61 (12H, m, Ph). 31P NMR (DMSO-d6): d (ppm) 22.19 (s).
13C NMR (DMSO-d6): d (ppm) 20.84 (3CH3); 30.11 (d, 3JPC = 11.2 Hz,
The m (CO) band, which is sensitive to complexation, is observed
for complexes at higher frequencies compared to the parent ylides,
indicating the coordination of the ylide through carbon atom in
each case [18]. 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 [5]. C-Coordination causes an
increase in m (CO) and a decrease in m (P+–Cꢁ), while for O-coordi-
nation a lowering for both frequencies is expected [9d]. The P–C
bands for complexes 1 and 2 overlapped with other intense bands
present at the same regions and thus were not seen.
1
1
COCH3); 49.51 (d, JPC = 41.2 Hz, CH); 119.64 (d, JPC = 91.2 Hz, p-
tolyl (i)); 130.42 (d, 3JPC = 13.0 Hz, p-tolyl (m)); 133.41
2
(d, JPC = 10.3 Hz, p-tolyl (o)); 143.87 (p-tolyl (p)); 198.00 (CO).
2.5.3. Data for [(Y2) ꢀ HgCl2]2 (3)
Yield 0.173 g, 78%. mp 210–212 °C. Anal. Calc. for
C58H52Cl4Hg2N2O6P2: C, 47.13; H, 3.55; N, 1.90. Found: C, 47.24;
H, 3.52; N, 2.06%. IR (KBr disk): m (cmꢁ1) 1650 (C@O), 1599, 1523,
1345, 1304, 1285, 1184, 1111, 1029, 1006, 858, 822 (P–C) and
804. 1H NMR (DMSO-d6): d (ppm) 5.13 (1H, br, CH); 7.46–8.22
(16H, m, Ph). 31P NMR (DMSO-d6): d (ppm) 22.05 (s). 13C NMR
In the 1H NMR spectra, the signals due to the methinic protons
for complexes are doublet or broad. A similar behavior was ob-
served earlier in the case of ylide complexes of platinum(II) chlo-
ride [19]. The expected downfield shifts of 31P and 1H signals for
the PCH group upon complexation in the case of C-coordination
were observed in their corresponding spectra. The proton decou-
pled 31P NMR spectra show only one sharp singlet between 20.77
and 22.92 ppm in the complexes. The appearance of single signals
for PCH group in each of the 31P and 1H NMR spectra indicates the
presence of only one molecule for all the complexes, as expected
for C-coordination [4]. It must be noted that the O-coordination
of the ylide generally leads to the formation of a mixture of cisoid
and transoid isomers, giving rise to two different signals in the 31P
and 1H NMR spectra (Chart 1) [9a]. The 31P chemical shift values for
the complexes appear to be shifted downfield by about 7.6–
11.5 ppm with respect to the parent ylide, also indicating that
coordination of the ylide has occurred [4,5,20]. Satellites due to
coupling to 199Hg for ylidic complexes of Hg(II) halides are only ob-
served at low temperature [5a,20] or by solid-state 31P NMR [20]
and also in the case of Hg(NO3)2 ꢀ H2O as metal source [6]. Failure
to observe satellites in the above spectra was previously noted in
the ylide complexes of Hg(II) [21] and Ag(I) [9c], and was assigned
to a fast exchange of the ylide with the metal which caused ex-
change decoupling [21].
1
(DMSO-d6): d (ppm) 20.77 (3CH3); 49.11 (d, JPC = 84.8 Hz, CH);
1
122.76 (COPh (m)); 120.68 (d, JPC = 93.6 Hz, p-tolyl (i)); 128.73
3
(p-tolyl (p)); 129.69 (d, JPC = 12.80 Hz, p-tolyl (m)); 143.52 (COPh
2
(o)); 132.87 (d, JPC = 10.4 Hz, p-tolyl (o)); 143.41 (COPh (i));
148.69 (COPh (p)); 186.01 (CO).
2.5.4. Data for [(Y2) ꢀ HgBr2]2 ꢀ 2DMSO (4)
Yield 0.206 g, 83%. mp 213–214 °C. Anal. Calc. for
C58H52Br4Hg2N2O6P2: C, 42.07; H, 3.17; N, 1.69. Found: C, 42.52;
H, 3.12; N, 1.75%. IR (KBr disk): m (cmꢁ1) 1636 (C@O), 1598,
1520, 1499, 1400, 1342, 1316, 1287, 1184, 1108, 1024, 1006,
855, 828 (P–C) and 803. 1H NMR (DMSO-d6): d (ppm) 5.40 (1H,
2
d, JPH = 7.7 Hz, CH); 7.46–8.24 (16H, m, Ph). 31P NMR (DMSO-d6):
d (ppm) 22.00 (s). 13C NMR (DMSO-d6): d (ppm) 21.01 (3CH3); 49.85
(d, 1JPC = 60.3 Hz, CH); 122.98 (COPh (m)); 120.42 (d, 1JPC = 92.2 Hz,
3
p-tolyl (i)); 129.18 (p-tolyl (p)); 129.93 (d, JPC = 12.8 Hz, p-tolyl
2
(m)); 143.77 (COPh (o)); 133.11 (d, JPC = 10.5 Hz, p-tolyl (o));
143.17 (COPh (i)); 148.97 (COPh (p)); 187.27 (CO).
2.5.5. Data for [(Y2) ꢀ HgI2]2 (5)
Yield 0.210 g, 76%. mp 215–216 °C. Anal. Calc. for C58H52Hg2I4-
N2O6P2: C, 37.78; H, 2.84; N, 1.52. Found: C, 37.87; H, 2.81; N,
1.55%. IR (KBr disk): m (cmꢁ1) 1635 (C@O), 1598, 1521, 1400,
1343, 1286, 1182, 1108, 1023, 1007, 856, 826 (P–C) and 801. 1H
The most interesting aspect of the 13C NMR spectra of the com-
plexes is the upfield shift of the signals due to the ylidic carbon
atoms. Such an upfield shift was observed in [PdCl(g3-2-
XC3H4)(C6H5)3PCHCOR] (X = H, CH3; R = CH3, C6H5), and is due to
the change in the hybridization of the ylidic carbon atom on coor-
dination [22]. The downfield shifts of the carbonyl C atom in the
complexes are 5–10 ppm compared to the same C atom in the par-
ent ylides, indicating a much lower shielding of carbon of the CO
group in these complexes.
2
NMR (DMSO-d6): d (ppm) 5.21 (1H, d, JPH = 9.5 Hz, CH); 7.43–
8.17 (16H, m, Ph). 31P NMR (DMSO-d6): d (ppm) 20.78 (s). 13C
1
NMR (DMSO-d6): d (ppm) 21.67 (3CH3); 51.06 (d, JPC = 83.2 Hz,
1
CH); 123.60 (COPh (m)); 121.3 (d, JPC = 93.1 Hz, p-tolyl (i));
3
129.63 (p-tolyl (p)); 130.48 (d, JPC = 12.7 Hz, p-tolyl (m)); 144.27
2
(COPh (o)); 133.67 (d, JPC = 10.6 Hz, p-tolyl (o)); 144.28
3
(d, JPC = 2.4 Hz, COPh (i)); 149.32 (COPh (p)); 186.91 (CO).
3. Results and discussion
3.2. X-ray crystallography
The reaction of mercury halides with ylides in a 1:1 stoichiom-
etry afforded halide-bridged dimeric structures 1–5 (Scheme 1)
containing C-coordinated ylide ligands.
Table 1 provides the crystallographic results and refinement
information for complexes 2 and 4 (Scheme 1). The molecular
P+(p-tolyl)3
CH
X
O
X
R
CH3OH
Hg
Hg
(p-tolyl)3PCHC(O)R+ HgX2
R
rt
X
X
O
CH
(1): R = CH3,
(2): R = CH3,
X = Cl
X = Br
P+(p-tolyl)3
(3): R = C6H4NO2, X = Cl
(4): R = C6H4NO2, X = Br
(5): R = C6H4NO2, X = I
Scheme 1.