the presence of only one chemically distinct mercury ethyl group.
Assuming that the equivalence is not coincidental, a plausible
explanation to account for the observation of a single mercury
ethyl group is chemical exchange involving dissociation of [HgEt]+.
SHgCH2CH3], 128.6 [d,1JC–H = 161, 1 C of HO2CC6H4SHgCH2-
CH3], 129.9 [d, 1JC–H = 160, 1 C of HO2CC6H4SHgCH2CH3], 135.4
[d,1JC–H = 161, 1 C of HO2CC6H4SHgCH2CH3], 136.2 [s, 1 C of
HO2CC6H4SHgCH2CH3], 137.3 [s, 1 C of HO2CC6H4SHgCH2-
1
CH3], 170.2 [s, 1 C of HO2CC6H4SHgCH2CH3]. 199Hg{ H} NMR
(DMSO): -788 [tq]. IR Data (KBr, cm-1): 3066 (s), 2963 (s), 2942
(s), 2909 (s), 2856 (s), 2725 (m), 2638 (m), 2544 (m), 1921 (w), 1692
(vs), 1589 (m), 1556 (m), 1468 (s), 1424 (m), 1403 (vs), 1302 (s),
1282 (s), 1251 (vs), 1172 (m), 1138 (m), 1109 (w), 1049 (s), 1032
(m), 946 (w), 902 (m), 809 (m), 787 (w), 732 (vs), 708 (m), 696 (m),
643 (m).
Conclusions
In summary, thimerosal is protonated selectively by HCl at the
carboxylate oxygen atom to give the mercury ethyl derivative
(ArCO H)SHgEt, rather than cleave the Hg–Et bond and eliminate
2
ethane. The carboxylate oxygen is also subject to electrophilic
attack by [HgEt]+ to give [(ArCO HgEt)SHgEt]2. Despite the formal
2
similarity of the reactions involving H+ and [HgEt]+, however, the
2
Deprotonation of (ArCO H)SHgEt
protonated derivative (ArCO H)SHgEt exists as a hydrogen bonded
2
A suspension of (ArCO H)SHgEt (20 mg, 0.052 mmol) in D2O
2
dimer in the solid state, while [(ArCO HgEt)SHgEt]2 is tetranuclear,
2
was treated with NaOH (0.28 mL of 0.225 M NaOH in D2O,
0.063 mmol), thereby resulting in the formation of a solution.
The sample was monitored by 1H NMR spectroscopy which
with the mercury centers being connected by bridging carboxylate
groups.
demonstrated the formation of [(ArCO )SHgEt]Na.
2
Experimental
Thermal stability of (ArCO H)SHgEt
2
General considerations
(a) A solution of (A◦rCO H)SHgEt (ca. 20 mg) in CDCl3 (ca. 0.7 mL)
2
All manipulations were performed using a combination of glove-
box, high-vacuum and Schlenk techniques under a nitrogen or
argon atmosphere, except where otherwise stated. Solvents were
purified and degassed by standard procedures. NMR spectra were
measured on Bruker 300 DRX, Bruker 400 DRX and Bruker
1
was heated at 150 C. The sample was monitored by H NMR
spectroscopy which demonstrated that (ArCO H)SHgEt is stable
2
with respect to elimination of ethane over a period of 3 d.
(b) A solution of (ArCO H)SHgEt (ca. 20 mg) in CD3OD (ca.
2
0.7 mL) was heated at 140 ◦C. The sample was monitored by 1H
1
Avance 500 DMX spectrometers. H NMR spectra are reported
NMR spectroscopy which demonstrated that (ArCO H)SHgEt is
2
in ppm relative to SiMe4 (d = 0) and were referenced internally
with respect to the protio solvent impurity (d 7.26 for CDCl332 and
5.32 for CD2Cl233). 13C NMR spectra are reported in ppm relative
to SiMe4 (d = 0) and were referenced internally with respect to
the solvent (d = 39.52 for DMSO).32 199Hg NMR chemical shifts
are reported relative to HgMe2 (d = 0) but in view of the toxicity
of the latter compound, the spectra were referenced externally
with respect to HgI2 (1 M in d6-DMSO, d = -3106).34 Coupling
constants are given in hertz. IR spectra were recorded as KBr
pellets on a Nicolet Avatar DTGS spectrometer, and the data
are reported in reciprocal centimeters. Thimerosal (Acros) and
EtHgCl (Strem) were obtained commercially.
stable with respect to elimination of ethane over a period of 12 h.
Synthesis of [(ArCO HgEt)SHgEt]2
2
A mixture of thimerosal (100 mg, 0.247 mmol) and EtHgCl
(59 mg, 0.223 mmol) in water (1 mL) and methanol (2 mL)
was stirred for 5 min. After this period, the mixture was filtered
and the precipitate was washed sequentially with water (3 ¥
1 mL) and methanol (2 ¥ 2 mL) and dried in vacuo to give
[(ArCO HgEt)SHgEt]2 as a white solid (47 mg, 35%). Anal. calcd
2
for [(ArCO HgEt)SHgEt]2·6H2O: C 19.9%, H 3.0%. Found: C 19.3%,
2
1
3
3
H 2.1%. H NMR (CD2Cl2): 1.32 [t, JH–H = 8, JH–Hg = 273,
3
6 H of H3CCH2HgO2CC6H4SHgCH2CH3], 1.83 [q, JH–H
=
Synthesis of (ArCO H)SHgEt
2
8, 2JH–Hg = 193, 4 H of H3CCH2HgO2CC6H4SHgCH2CH3], 7.12
3
A solution of thimerosal (200 mg, 0.49 mmol) in water (5 mL) was
treated with HClaq (0.040 mL of 12.2 M, 0.49 mmol), resulting
in the immediate formation of a white precipitate, which was
extracted into CH2Cl2 (7 mL). The dichloromethane extract was
washed with water (3 ¥ 3 mL) and the volatile components
[t, JH–H = 8, 1 H of H3CCH2HgO2CC6H4SHgCH2CH3, 7.21 [t,
3JH–H = 8, 1 H of H3CCH2HgO2CC6H4SHgCH2CH3], 7.54 [m,
2 H of H3CCH2HgO2CC6H4SHgCH2CH3]. 13C NMR (DMSO):
1
2
13.9 [q, JC–H = 126, JHg–c = 91, 2 C of H3CCH2HgO2CC6-
1
1
H4SHgCH2CH3], 20.7 [t, JC–H = 133, JHg–C = 1570, 2 C of
H3CCH2HgO2CC6H4SHgCH2CH3], 124.4 [d,1JC–H = 162, 1 C of
H3CCH2HgO2CC6H4SHgCH2CH3], 127.9 [d,1JC–H = 160, 1 C
were then removed in vacuo to give (ArCO H)SHgEt as a white
2
solid (147 mg, 79%). Anal. calcd for (ArCO H)SHgEt: C 28.2%,
2
1
1
H 2.6%. Found: C 28.3%, H 2.6%. H NMR (CDCl3): 1.35 [t,
of H3CCH2HgO2CC6H4SHgCH2CH3], 128.6 [d, JC–H = 158, 1
3JH–H = 8, 3JH–Hg = 252, 3 H of HO2CC6H4SHgCH2CH3], 1.89 [q,
3JH–H = 8, 2JH–Hg = 168, 2 H of HO2CC6H4SHgCH2CH3], 7.30 [t,
3JH–H = 8, 1 H of HO2CC6H4SHgCH2CH3], 7.39 [t, 3JH–H = 8, 1 H
of HO2CC6H4SHgCH2CH3], 7.61 [d, 3JH–H = 8, 1 H of HO2CC6-
H4SHgCH2CH3], 8.25 [d, 3JH–H = 8, 1 H of HO2CC6H4SHgCH2-
CH3], 11.79 [s, 1 H of HO2CC6H4SHgCH2CH3]. 13C NMR
C of H3CCH2HgO2CC6H4SHgCH2CH3], 135.3 [d,1JC–H = 162,
1 C of H3CCH2HgO2CC6H4SHgCH2CH3], 135.5 [s, 1 C of
H3CCH2HgO2CC6H4SHgCH2CH3], 141.2 [s, 1 C of H3CCH2-
HgO2CC6H4SHgCH2CH3], 173.7 [s, 1 C of H3CCH2HgO2-
CC6H4SHgCH2CH3]. IR Data (KBr, cm-1): 3056 (w), 3043 (w),
2973 (m), 2946 (m), 2913 (m), 2858 (m), 1600 (vs), 1577 (s), 1460
(m), 1425 (m), 1338 (vs), 1271 (m), 1254 (m), 1231 (w), 1183 (m),
1142 (m), 1115 (w), 1048 (m), 1033 (w), 960 (w), 949 (w), 857 (m),
792 (w), 752 (vs), 732 (m), 711 (m), 689 (m), 651 (m).
1
2
(DMSO): 13.7 [q, JC–H = 124, JHg–C = 73, 1 C of HO2CC6H4-
SHgCH2CH3], 25.4 [t, 1JC–H = 132, 1JHg–C = 1362, 1 C of HO2CC6-
1
H4SHgCH2CH3], 124.4 [d, JC–H = 163, 1 C of HO2CC6H4-
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The Royal Society of Chemistry 2009
Dalton Trans., 2009, 4327–4333 | 4331
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