Bis(n-alkanethiolato)mercury(II) compounds, Hg(SCnH2n+1)2 (n = 1 to 10, 12): Preparation methods, vibrational spectra, GC/MS investigations, and exchange reactions with diorganyl disulfides

Article abstract of DOI:10.1021/ic000638b

Several preparative routes to bis(n-alkanethiolato)mercury(II) compounds of the general composition Hg(SC_nH_2n+1)₂ for n = 1-10, 12 (compounds 1-11, respectively) are presented, including the reaction of mercury(II) iodide with n-alkanethiols and triethylamine as an auxiliary base, as well as the reaction of mercury(II) chloride with trimethylsilyl methyl sulfide as an example for this particular type of exchange reaction using trimethylsilyl sulfides as thiolate transferring reagents. With respect to the possibility of mobilizing these compounds into the environment under special natural surroundings, as for example found in some natural gas reservoirs, the reactivity of the title compounds toward excess di-n-alkyl disulfides leading to the exchange of the thiolate functional groups of both the mercury compounds and the disulfides is investigated. Equilibration reactions of specifically stoichiometric amounts of Hg(SC₃H₇)₂ (3) and C₇H₁₅SSC₇H₁₅, as well as Hg(SC₇H₁₅)₂ (7) and C₃H₇SSC₃H₇ are investigated in more detail using the coupling of gas chromatography and mass spectrometry (GC/MS). The FT-IR and FT-Raman spectroscopic data of the solid title compounds are given and discussed. Assignments of v_s(Hg-S) and v_as(Hg-S) stretchings, as well as δ(C-S-Hg) and δ(S-Hg-S) bendings are reported and discussed in comparison to literature data. The spectroscopic data suggest mercury to be two-coordinated in all studied compounds with the exception of Hg(SC₄H₉)₂ (4). This particular compound obviously contains a four-coordinated central mercury atom. The title compounds were analyzed by means of GC/MS, which indicated that the compounds (i) decompose at elevated temperatures, mainly to form mercury and the corresponding disulfide, and (ii) are monomer in the gas phase.

Full text of DOI:10.1021/ic000638b

Inorg. Chem. 2001, 40, 977-985
977
Bis(n-alkanethiolato)mercury(II) Compounds, Hg(SCnH2n+1)2 (n ) 1 to 10, 12): Preparation
Methods, Vibrational Spectra, GC/MS Investigations, and Exchange Reactions with
Diorganyl Disulfides†
Gerhard G. Hoffmann,*,‡ Wolfgang Brockner,§ and Ingeborg Steinfatt
Institut fu¨r Erdo¨l- und Erdgasforschung, Walther-Nernst-Str. 7, D-38678 Clausthal-Zellerfeld, Germany,
Institut fu¨r Anorganische und Analytische Chemie, Technische Universita¨t Clausthal, Paul-Ernst-Str. 4,
D-38678 Clausthal-Zellerfeld, Germany, and Institut fu¨r Technische Chemie, Technische Universita¨t
Clausthal, Erzstr. 18, D-38678 Clausthal-Zellerfeld, Germany
ReceiVed June 14, 2000
Several preparative routes to bis(n-alkanethiolato)mercury(II) compounds of the general composition Hg(SCnH2n+1 2
)
for n ) 1-10, 12 (compounds 1-11, respectively) are presented, including the reaction of mercury(II) iodide
with n-alkanethiols and triethylamine as an auxiliary base, as well as the reaction of mercury(II) chloride with
trimethylsilyl methyl sulfide as an example for this particular type of exchange reaction using trimethylsilyl sulfides
as thiolate transferring reagents. With respect to the possibility of mobilizing these compounds into the environment
under special natural surroundings, as for example found in some natural gas reservoirs, the reactivity of the title
compounds toward excess di-n-alkyl disulfides leading to the exchange of the thiolate functional groups of both
the mercury compounds and the disulfides is investigated. Equilibration reactions of specifically stoichiometric
amounts of Hg(SC3H7)2 (3) and C7H15SSC7H15, as well as Hg(SC7H15)2 (7) and C3H7SSC3H7 are investigated in
more detail using the coupling of gas chromatography and mass spectrometry (GC/MS). The FT-IR and FT-
Raman spectroscopic data of the solid title compounds are given and discussed. Assignments of νs(Hg-S) and
νas(Hg-S) stretchings, as well as δ(C-S-Hg) and δ(S-Hg-S) bendings are reported and discussed in comparison
to literature data. The spectroscopic data suggest mercury to be two-coordinated in all studied compounds with
the exception of Hg(SC4H9)2 (4). This particular compound obviously contains a four-coordinated central mercury
atom. The title compounds were analyzed by means of GC/MS, which indicated that the compounds (i) decompose
at elevated temperatures, mainly to form mercury and the corresponding disulfide, and (ii) are monomer in the
gas phase.
Introduction
Because of scarce and even poor structural data (further
refinements of the structural data of some compounds seem to
Despite the fact that bis(n-alkanethiolato)mercury(II) com-
pounds of the general composition Hg(SR)2 have been long
known,1-5 there still remain a lot of unsolved domains concern-
ing their chemistry and spectroscopic behavior. With respect
to the chemistry of mercury that has attracted considerable
interest, due to the extremely high toxicity of the metal itself,
its inorganic compounds, and even more so its organic
compounds to living systems,6-12 we have investigated several
preparative routes to a series of homoleptic compounds of the
general composition Hg(SCnH2n+1)2 for n ) 1-10, 12 (com-
pounds 1-11, respectively).
be necessary) available for these compounds,13-19 the solid-
state vibrational spectra are of special interest, too,20 so much
the more as some controversial discussions with respect to the
assignments of fundamental vibrations still exist.21,22a In addi-
1
tion, H NMR spectroscopic data of these homoleptic com-
pounds do not contribute spectacular knowledge.23 Moreover,
the reactivity of the title compounds toward thiolate functional
(11) (a) Nriagu, J. O. (Ed.) The Biogeochemistry of Mercury in the
EnVironment; Elsevier/North-Holland Biomedical Press: Amsterdam,
1979. (b) Sigel, A.; Sigel, H. (Eds.) Metal Ions in Biological Systems,
Vol. 34; Mercury and its Effects on EnVironment and Biology; Marcel
Dekker: New York, 1997.
† Dedicated to Professor Max Schmidt on the occasion of his 75th
birthday (October 13, 2000).
(12) Craig, P. J. (Ed.) Organometallic Compounds in the EnVironment;
* To whom correspondence should be addressed. E-mail:
Gerhard.Hoffmann@tu-clausthal.de.
Longman Group Ltd.: Harlow, England, 1986.
(13) Wells, A. F. Z. Kristallogr. 1937, 96, 435.
(14) Kunchur, N. R. Nature (London) 1964, 4, 468.
‡ Institut fu¨r Erdo¨l- und Erdgasforschung.
§ Institut fu¨r Anorganische und Analytische Chemie, Technische Uni-
versita¨t Clausthal.
(15) Bradley, D. C.; Kunchur, N. R. J. Chem. Phys. 1964, 40, 2258.
(16) Bradley, D. C.; Kunchur, N. R. Can. J. Chem. 1965, 43, 2786.
(17) Stålhandske, C.; Zintl, F. Acta Crystallogr., Sect. C. 1987, 43, 863.
(18) Hoffmann, G. G.; Steinfatt, I.; Brockner, W.; Kaiser, V. Z. Naturforsch.
1999, 54b, 887.
(19) Wright, J. G.; Tsang, H.-T.; Penner-Hahn, J. E.; O’Halloran, T. V. J.
Am. Chem. Soc. 1990, 112, 2434.
(20) Fleissner, G.; Kozlowski, P. M.; Vargek, M.; Bryson, J. W.;
O’Halloran, T. V.; Spiro, T. G. Inorg. Chem. 1999, 38, 3523.
(21) Biscarini, P.; Fusina, L.; Nivellini, G. J. Chem. Soc., Dalton Trans.
1974, 2140.
(22) (a) Canty, A. J.; Kishimoto, R.; Deacon, G. B.; Farquharson, G. J.
Inorg. Chim. Acta 1976, 20, 161. (b) Canty, A. J. Spectrochim. Acta
1981, 37A, 283 and references therein.
Institut fu¨r Technische Chemie, Technische Universita¨t Clausthal.
(1) Zeise, W. C. J. Prakt. Chem. 1834, 1, 257, 396 and 457.
(2) Zeise, W. C. Poggendorffs Ann. 1834, 31, 369.
(3) Zeise, W. C. Ann. Chim. Phys. 1834, 56, 87.
(4) Jackson, C. L.; Oppenheim, A. Ber. Dtsch. Chem. Ges. 1876, 8, 1032.
(5) Wertheim, E. J. Am. Chem. Soc. 1929, 51, 3661.
(6) Wood, J. M. EnVironment 1972, 14, 33.
(7) Wood, J. M. Science 1974, 183, 1049.
(8) D’Itri, P. A.; D’Itri, F. M. Mercury Contamination: A Human Tragedy;
John Wiley & Sons: New York, 1977.
(9) Rabenstein, D. L. Acc. Chem. Res. 1978, 11, 100.
(10) Rabenstein, D. L. J. Chem. Educ. 1978, 55, 292.
10.1021/ic000638b CCC: $20.00 © 2001 American Chemical Society
Published on Web 02/02/2001

978 Inorganic Chemistry, Vol. 40, No. 5, 2001
Hoffmann et al.
the title compounds (cf. Identification of Hg(SR)2 ...) as well as an
acceleration of the exchange processes of the title compounds with the
diorganyl disulfides on the GC injector system, thus influencing the
equilibration. That is the reason these exchange reactions can only be
considered qualitatively. Nevertheless, the exchange reactions proceed
already at ambient temperatures, as documented in the different total
ion chromatograms (Figure 1) recorded during the equilibration
experiments.
Elemental analyses (C, H) were performed with a Heraeus elemental
analyzer, and sulfur was analyzed according to the method of
Scho¨niger.31 DSC and TG measurements were obtained using a 910
differential scanning calorimeter, a 951 thermogravimetric analyzer,
and a Thermal Analyst 2100 for data analysis.
Preparations. Caution! Because of the toxicity of mercury and its
compounds all reactions were carried out in Schlenk tubes. The contact
of mercury compounds with metallic apparatses can lead to parasitic
reactions. Therefore, the use of metallic apparatses was strictly aVoided
with the exception of GC and GC/MS experiments (syringes and
needles).
groups is of particular importance, due to the great affinity of
sulfur for mercury.1-5 Especially its affinity for thiols is
generally used to remove mercury from the body when poisoned
by mercury and its compounds.24-26 Furthermore, similar
compounds play an important role in the biochemistry of
mercury.19,27-29 Previously, some of us reported the reaction
of mercury with diorganyl disulfides, (CH3)2S2 and (C6H5)2S2,
to result in the formation of the corresponding bis(n-organo-
thiolato) mercury(II) derivatives.23,30 Generally, these reactions
play a pivotal role in some natural systems because of their
ability to mobilize and transport mercury into the environment.6-12
The present work will focus on the reactivity of the title
compounds toward organic disulfides, which leads to the
exchange of the thiolate functional groups of both the mercury
compounds and the disulfides. Generally, the understanding of
such exchange reactions provides detailed insight into the
fundamental processes of mobilization and transport mechanisms
of these environmentally important compounds.
Analytical data, preparative methods, and yield of the title com-
pounds are given in Table 1.
Moreover, we extended our investigations on the IR and
Raman spectra of these compounds in the solid state to allow
comparisons to be made of both the title compounds with each
other and the collected data with those already published.
General Procedures for the Preparation of Bis(n-alkanethiolato)-
mercury(II) Compounds, Hg(SCnH2n+1)2, (n ) 1-10, 12). (a)
Reactions of n-Alkanethiols, (n ) 1-10, 12) with Mercury(II)
Nitrate.23 n-Alkanethiol (2 equiv) was added to a solution of mer-
cury(II) nitrate (1 equiv) in 30 mL (1, 3-9, 11) or 120 mL (2, 10)
portions of 1:1 ethanol/water (cf. Table 1). A voluminous precipitate
immediately formed. After stirring for 12 h in the dark, the colorless
crystals were collected by filtration and washed twice with cold absolute
ethanol. After removal of the solvent in vacuo the compounds were
used without further purification.
(b) Reactions of n-Alkanethiols, (n ) 2-5, 8, 10, 12) and
Triethylamine with Mercury(II) Iodide.18 n-Alkanethiol (2.2 equiv)
was added to a solution of mercury(II) iodide (1 equiv) in 30 mL (2-
5, 10, 11) or 90 mL (8) portions of absolute ethanol (cf. Table 1). A
voluminous precipitate immediately formed that became microcrystal-
line after adding triethylamine (2.2 equiv) to the reaction mixture. After
filtration, the precipitate was washed twice with water. The further
workup of the reaction products followed the procedure described in
part a.
Experimental Section
All solvents and chemicals were reagent grade and used as received.
FT-Raman spectra were recorded with a Raman module FRA 106 (Nd:
YAG laser, 1064 nm, <200 mW) attached to a Bruker IFS 66v
interferometer. FT-IR spectra were done with KBr and CsI pellets and/
or Nujol grindings between PE plates (the latter was done to make
sure that possible exchange reactions of KBr and CsI with the title
compounds do not seriously affect the IR spectra, as well as to obtain
IR spectra at frequencies below 200 cm-1) with the interferometer (in
the range 500-50 cm-1) and a Perkin-Elmer Paragon 1000 FT-IR
spectrometer (in the range 4000-200 cm-1), respectively.
Gas chromatographic investigations (GC) were performed using a
Hewlett-Packard Model 5890 Series II instrument, equipped with a 30
m DB 5 capillary column (i.d. 0.25 mm) and a Hewlett-Packard flame
photometric detector (initial temperature 35 °C and ramping to 320 °C
at 5 °C/min). Injector and detector temperatures were set to 280 °C,
and the helium carrier-gas flow was 1 mL/min. Gas chromatography-
mass spectrometry (GC/MS) was performed using a Hewlett-Packard
Model 6890 A instrument, equipped with a 30 m HP-5MS capillary
column (i.d. 0.25 mm) and a Hewlett-Packard 5973 MS detector (initial
temperature 40 °C and ramping to 290 °C at 5 °C/min). The injector
temperature was set to 250 °C and the ion source to 230 °C, and the
helium carrier-gas flow was 1 mL/min. Mass spectra were obtained
by electron ionization at 70 eV; resolution, ∆m ) 1; scan range, 45-
500 or 45-750; scan speed, 1.66 scans/min. The injector system of
the GC/MS was a split/splitless inlet.
(c) Reactions of n-Alkanethiols, (n ) 2, 5, 6, 8) with Hg(SCn-
H
2n+1)2.18 n-Alkanethiol (2.2 equiv) was added to a suspension of bis-
(n-alkanethiolato′)mercury(II) (1 equiv) in 30 mL of absolute ethanol
(cf. Table 1). After stirring for 12 h in the dark at ambient temperature,
a solution formed, which was evaporated to dryness. The remaining
colorless precipitate was washed twice with cold absolute ethanol and
used without further purification after removal of the solvent in vacuo.
The progress of the reaction was documented by means of GC.
(d) Reactions of Organic Disulfides, (CnH2n+1)2S2, (n ) 1-3, 9,
10) with Hg(SCnH2n+1)2. Di-n-alkyl disulfide (1.1 equiv) was added
to a suspension of bis(n-alkanethiolato′)mercury(II) (1 equiv) in 30
mL of absolute ethanol (cf. Table 1). After stirring for 12 h in the dark
at 50 °C, a solution formed, which was treated as described in part c,
provided that the exchanged disulfide has a lower boiling point than
the exchanging disulfide. Otherwise the compound was collected with
lower yield by cooling the solution. The progress of the reaction was
followed by means of GC.
(e) Redox Reactions of Organic Disulfides (CnH2n+1)2S2, (n ) 1-3,
7, 8) with Mercury.23,30 Di-n-alkyl disulfide (5 mL) was stirred with
mercury for 2-4 weeks in the dark at temperatures slightly higher than
ambient temperature. A grayish precipitate resulted. Then 20 mL of
CH2Cl2 was added to the reaction mixture. Excess mercury slowly
separated. The solution was decanted and evaporated to dryness. The
white precipitate was treated as described in part c.
It has to be taken into account that the high temperatures applied
during the GC investigations contribute to both the decomposition of
(23) Steinfatt, I.; Hoffmann, G. G. Z. Naturforsch. 1994, 49b, 1507.
(24) Gilman, A.; Allen, R. P.; Philips, F. S.; John, E. St. J. Clin. InVest.
1946, 25, 549.
(25) Longcope, W. T.; Luetscher, jun., J. A.; Calkins, E.; Grob, D.; Bush,
S. W.; Eisenberg, H. J. Clin. InVest. 1946, 25, 557.
(26) Stocken, L. A. Biochem. J. 1947, 41, 358.
(27) Watton, S. P.; Wright, J. G.; MacDonnell, F. M.; Bryson, J. W.; Sabat,
M.; O’Halloran, T. V. J. Am. Chem. Soc. 1990, 112, 2824.
(28) Wright, J. G.; Natan, M. J.; MacDonnell, F. M.; Ralston, D. M.;
O’Halloran, T. V. Prog. Inorg. Chem. 1990, 38, 323; loc.cit.
(29) Gruff, E. S.; Koch, S. A. J. Am. Chem. Soc. 1990, 112, 1245.
(30) Hoffmann, G. G.; Steinfatt, I. ACS, DiV. EnVironment. Chem. Prepr.
1997, 37 (1), 298. Hoffmann, G. G., presented in part at the 18th
International Symposium on the Organic Chemistry of Sulfur, Florence,
July, 1998. Hoffmann, G. G., presented in part at the 15th International
Conference of Chemical Thermodynamics, Porto, July, 1998. Hoff-
mann, G. G.; Steinfatt, I. Phosphorus, Sulfur Slilicon 1999, 153/154,
423. Hoffmann, G. G., presented in part at the 218th ACS National
Meeting, New Orleans, 1999; DiV. Inorg. Chem. Abstr. 1999, 336.
(f) Reactions of HgCl2 with Trimethylsilyl methyl sulfide,
[(CH3)3SiSCH3]. Trimethylsilyl methyl sulfide (11.1 g, 9.25 mmol)
was added to a suspension of 1.14 g (4.20 mmol) of mercury(II) chloride
in 30 mL of CH2Cl2. After stirring of the reaction mixture at ambient
(31) Scho¨niger, W. Microchim. Acta 1956, 869.

Bis(n-alkanethiolato)mercury(II) Compounds
Inorganic Chemistry, Vol. 40, No. 5, 2001 979
Equilibration Experiments. (a) 3 and C7H15SSC7H15. Compound
3 (110 mg, 0.314 mmol) was dissolved in a mixture of 82.2 mg (0.314
mmol) of C7H15SSC7H15 in 7 mL of CH2Cl2. A solution immediately
formed which was stirred at ambient temperature in the dark. After
48, 216, and 360 h, 1 µL samples of the solution were injected into
the GC/MS device. The following compounds could be detected using
GC/MS: (1) C3H7SSC3H7 (M+ ) 150), (2) C3H7SSC7H15 (M+ ) 206),
(3) 3 (M+ ) 350; Hg isotope pattern), (4) C7H15SSC7H15 (M+ ) 262),
(5) C3H7SHgSC7H15 (12) (M+ ) 406; Hg isotope pattern), and (6) 7
(M+ ) 462; Hg isotope pattern). Additionally, the following compounds
were formed in very low concentrations as decomposition products,
mainly caused by the high temperatures applied during the GC/MS
investigations:18 (7) C3H7SC3H7 (M+ ) 118), (8) C3H7SSSC3H7 (M+
) 182), (9) C7H15SC7H15 (M+ ) 230), and (10) C7H15SSSC7H15 (M+
) 294). After 384 h, excess C7H15SSC7H15 was added to the reaction
mixture. Further GC/MS chromatograms were recorded after 528 and
696 h, respectively.
(b) 7 and C3H7SSC3H7. Compound 7 (201 mg, 0.434 mmol) was
dissolved in a mixture of 65.2 mg (0.434 mmol) of C3H7SSC3H7 in 10
mL CH2Cl2. After stirring at ambient temperature in the dark, the
mercury compound was completely dissolved. After 48, 216, and 360
h, 1 µL samples of the solution were injected into the GC/MS device.
The following compounds could be found using GC/MS: (1) C3H7-
SSC3H7 (M+ ) 150), (2) C3H7SSC7H15 (M+ ) 206), (3) 3 (M+ ) 350;
Hg isotope pattern), (4) C7H15SSC7H15 (M+ ) 262), (5) 12 (M+
)
406; Hg isotope pattern), and (6) 7 (M+ ) 462; Hg isotope pattern).
The same decomposition products as in part a could be found. After
384 h, excess C3H7SSC3H7 was added to the reaction mixture. Further
GC/MS chromatograms were recorded after 528 and 696 h, respectively.
(c) 3, 7, C7H15SSC7H15, and C3H7SSC3H7 (Control Experiment).
Compounds 3 (78.0 mg, 0.222 mmol) and 7 (109 mg, 0.235 mmol)
were dissolved in a mixture of 35.4 mg (0.235 mmol) C3H7SSC3H7
and 38.4 mg (0.222 mmol) of C7H15SSC7H15 in 12 mL of CH2Cl2. A
solution immediately formed which was stirred at ambient temperature
in the dark. After 48, 216, 360, 528, and 696 h, 1 µL samples of the
solution were injected into the GC/MS device. The following com-
pounds could be detected by their mass spectra: (1) C3H7SSC3H7 (M+
) 150), (2) C3H7SSC7H15 (M+ ) 206), (3) 3 (M+ ) 350; Hg isotope
pattern), (4) C7H15SSC7H15 (M+ ) 262), (5) 12 (M+ ) 406; Hg isotope
pattern), and (6) 7 (M+ ) 462; Hg isotope pattern). The same
decomposition products as in part a could be found.
Results and Discussion
Synthesis. Bis(organothiolato)mercury(II) compounds can be
prepared by several methods. The most common preparation is
achieved by the reaction of Hg(CN)2 with 2 equiv of RSH.5,32-34
Instead of Hg(CN)2, other starting compounds are often used,
such as HgO,1-3,35 Hg(ClO4)2,17 Hg(OAc)2,36,37 Hg[N(SiCH3)2]2,38
and Hg(NO3)2,23 respectively. In addition, the reaction of HgCl2
with alkali mercaptides23,38,39 as well as photochemically40 or
electrochemically41 initiated redox reactions starting from
mercury and organic disulfides are known.
With respect to the focus of these investigations on the
mobilization of mercury, it was of particular interest to get
information about the reactivity of Hg(SR)2 compounds toward
organic thiols18 and organic disulfides, respectively. Therefore,
(32) Claesson, P. J. Prakt. Chem. 1877, 15, 193.
(33) Rheinboldt, H.; Dewald, M.; Diepenbruck, O. J. Prakt. Chem. 1931,
130, 133.
(34) Rheinboldt, H.; Mott, F.; Motzkus, E. J. Prakt. Chem. 1932, 134, 257.
(35) Mann, F. G.; Purdie, D. J. Chem. Soc. 1935, 1549.
(36) Sachs, G. Ber. Dtsch. Chem. Ges. 1921, 54, 1849.
(37) Silveira, C. C.; Braga, A. L.; Larghi, E. L. Organometallics 1999, 18,
5183.
(38) Bochmann, M.; Webb, K. J. J. Chem. Soc., Dalton Trans. 1991, 2325.
(39) Alsina, T.; Clegg, W.; Fraser, K. A.; Sola, J. J. Chem. Soc., Dalton
Trans. 1992, 1393.
Figure 1. Total ion chromatograms (tics) of equilibrium 7 recorded
after a reaction period of (a) 48 h, (b) 216 h, (c) 360 h, (d) 528 h (after
addition of excess (C3H7S)2 to the reaction mixture after a reaction
time of 384 h), and (e) 696 h.
temperature for 12 h, a colorless solution formed, which was evaporated
to dryness. The workup of the remaining colorless precipitate followed
the procedure described in part a.
(40) Brandt, G. A. R.; Emele´us, H. J.; Haszeldine, R. N. J. Chem. Soc.
1952, 2198.
(41) Said, F. F.; Tuck, D. G. Inorg. Chim. Acta 1982, 59, 1.

980 Inorganic Chemistry, Vol. 40, No. 5, 2001
Table 1. Analytical Data, Preparation Methods, and Yields of 1-11
formula
Hoffmann et al.
yield
mp
dec max.
starting component(g, mmol)
no. (molecular weight)
C (%) H (%) Hg (%)a S (%)
(g)
(%)
(°C)
(°C)
1
Hg(SCH3)2
(294.79)
calcd
found
8.15
8.18
2.05
1.98
68.05
-
21.76 a: Hg(N O3)2
1.97, 5.75 a: 1.66 a: 97.9 none
1.42, 4.40 d: 1.15 d: 88.6
1.00, 4.99 e: 0.86 e: 58.5
1.14, 4.20 f: 1.18 f: 95.3
171
20.9
d: Hg(SC2H5)2
e: Hg
17520
f: HgCl2
2
Hg(SC2H5)2
(322.842)
calcd 14.88
found 14.70
3.12
3.01
62.13
-
19.87 a: Hg(N O3)2
8.15, 23.8 a: 7.50 a: 97.7 79.6
1.01, 2.22 b: 0.51 b: 71.1 765
0.40, 0.98 c: 0.11 c: 34.7 72-73 20
0.51, 1.73 d: 0.49 d: 87.7 7735
0.83, 4.14 e: 0.47 e: 35.2
1.75, 5.11 a: 1.62 a: 90.4 71
1.04, 2.29 b: 0.62 b: 77.2 71-725
0.39, 0.79 d: 0.15 d: 53.8 67-6920
0.57, 2.84 e: 0.17 e: 17.1 6735
1.66, 4.85 a: 1.75 a: 95,3 89
1.09, 2.40 b: 0.60 b: 66.0 85-865
81-8320
189.4
20.1
b: HgI2
c: Hg(SC5H11)2
d: Hg(SCH3)2
e: Hg
3
4
5
Hg(SC3H7)2
(350.894)
calcd 20.54
found 20.46
4.02
3.99
57.17
-
18.28 a: Hg(N O3)2
17.34 b: HgI2
d: Hg(SC8H17)2
e: Hg
16.92 a: Hg(N O3)2
16.56 b: HgI2
170
Hg(SC4H9)2
(378.946)
calcd 25.35
found 24.93
4.79
4.51
52.94
-
196.1
171.2
8535
Hg(SC5H11)2
(406.998)
calcd 29.51
found 29.00
5.45
5.34
49.29
-
15.76 a: Hg(N O3)2
15.67 b: HgI2
c: Hg(SCH3)2
14.74 a: Hg(N O3)2
1.72, 5.02 a: 2.04 a: 100 68.6
1.07, 2.36 b: 0.75 b: 78.3 745
0.30, 1.02 c: 0.39 c: 94.2 6635
1.88, 5.49 a: 2.35 a: 98.4 61.5
0.44, 1.36 c: 0.35 c: 59.0 5835
1.28, 3.74 a: 1.70 a: 98.3 81.1
0.44, 2.19 e: 0.19 e: 18.7 76-77 5
7535
6
7
Hg(SC6H13)2
(435.05)
Hg(SC7H15)2
(463.102)
calcd 33.13
found 32.80
calcd 36.31
found 35.87
6.02
5.63
6.53
6.52
46.11
-
43.31
-
169.9
197
14.1
13.85 a: Hg(N O3)2
13.0 e: Hg
c: Hg(SC2H5)2
8
Hg(SC8H17)2
(491.154)
calcd 39.12
found 39.03
6.98
6.99
40.84
-
13.06 a: Hg(N O3)2
13.28 b: HgI2
1.51, 4.41 a: 2.10 a: 97.0 74.8
234
3.62, 7.97 b: 3.56 b: 91.0 7135
c: Hg(SC10H21)2 0.43, 0.79 c: 0.28 c: 72.6
e: Hg
0.63, 3.14 e: 0.18 e: 11.7
1.24, 3.62 a: 1.72 a: 91.5
0.45, 1.53 d: 0.55 d: 69.4
8.15, 23.8 a: 11.2 a: 86.0 69.1
1.14, 2.50 b: 1.34 b: 97.6
0.24, 0.59 d: 0.26 d: 80.6
1.63, 4.76 a: 2.10 a: 73.2 96
1.27, 2.80 b: 1.61 b: 95.5
9
Hg(SC9H19)2
(519.206)
Hg(SC10H21)2
(547.258)
calcd 41.64
found 41.3 2 7.43
calcd 43.89
found 43.33
7.38
38.63
-
36.65
-
12.35 a: Hg(N O3)2
11.94 d: Hg(SCH3)2
11.72 a: Hg(N O3)2
10.98 b: HgI2
d: Hg(SC5H11)2
10.63 a: Hg(N O3)2
10
7.74
7.78
242
276
11
Hg(SC12H25)2
(603.362)
calcd 47.77
found 47.44
8.35
8.19
33.25
-
11.1
b: HgI2
a not determined.
a series of compounds was prepared by common methods23 to
be used for analytical purposes and in further experiments as
starting material. Furthermore, we extended the preparation to
two new methods, one starting from mercury(II) iodide,
alkanethiols, and trimethylamine and the other starting from
mercury(II) chloride and trimethylsilyl methyl sulfide as the
thiolate transferring reagent.
Ethanolic solutions of 1 equiv of HgI2 readily react at room
temperature with 2 equiv of the corresponding n-alkanethiol to
form voluminous colorless precipitates. By adding excess
triethylamine as an auxiliary base, the precipitate becomes
microcrystalline. The title compounds are obtained in high yield
according to eq 1:
pound is very easy, because the corresponding trimethyl-
chlorosilane can be evaporated together with the solvent.
Reactivity toward Organic Disulfides. Ligand exchange
reactions of mercury thiolates are of particular interest with
respect to biological systems. However, these reactions have
been the subject of investigations concerning mainly methyl-
mercury species.42,43 Bis(n-alkanethiolato)mercury(II) and or-
ganic disulfides easily exchange the thiolate functional groups
already at ambient temperature in solvents and without solvent
if the disulfide is employed in excess, according to eq 3:
Hg(SR)2 + R′SSR′ f Hg(SR′)2 + RSSR
R ) R′ ) alkyl
(3)
HgI2 + 2RSH + 2N(C2H5)3 f Hg(SR)2 + 2[HN(C2H5)3]I
GC and GC/MS investigations reveal the reaction to be an
equilibrium proceeding together with an exchange reaction of
the two diorganyl disulfide moieties resulting in the formation
of the asymmetric disulfide RSSR′ (eq 4):
(1)
R ) CH3-C5H11 (1-5), C8H17 (8), C10H21 (10), C12H25 (11)
For the second method, HgCl2 was suspended in dry benzene
and reacted with trimethylsilyl methyl sulfide according to eq
2:
RSSR + R′SSR′ a 2RSSR′
R ) R′ ) alkyl
(4)
Hg(SCH )
3 2 + 2(CH3)3SiCl (2)
HgCl2 + 2(CH3)3SiSCH3f
Previously, the latter reaction could be demonstrated to be
strongly accelerated by mercury or mercury thiolates.18
1
This method profits from the fact that the silyl sulfide is liquid
at ambient temperature in contrast to CH3SH boiling at
approximately 6 °C. Second, the separation of the title com-
(42) Bach, R. D.; Weibel, A. T. J. Am. Chem. Soc. 1976, 98, 6241.
(43) Canty, A. J.; Carty, A. J.; Malone, S. F. J. Inorg. Biochem. 1983, 19,
133.

Bis(n-alkanethiolato)mercury(II) Compounds
Table 2. IR and Raman Frequencies and Assignments of 1-5 in the Region of 800-50 cm-1 a
Hg(SCH3)2 (1) Hg(SC2H5)2 (2) Hg(SC3H7)2 (3) Hg(SC4H9)2 (4)
Inorganic Chemistry, Vol. 40, No. 5, 2001 981
Hg(SC5H11)2 (5)
assignment
(proposed)
RE IR RE IR RE IR
RE
IR
RE
IR
781 m
744 m
728 m, sh
720 vs
644 m
477 vw
438 vw
408 w
775 vvw
657 s
769 s
671 vw
657 m
741 s
748 vw
749 vw
723 m
458 m
750 w
729 s
724 m, sh
F(CH2)
ν(C-S)
695 m
694 s
723 s
724 m
714 m
643 w
476 vw
430 vw
413 vw
351 w
324 w
460 m
δ(C-C-C )
δ(C-C-C )
346 m
322 m
250 vb
367 w
δ(C-C-S)
330 s
411 w
395 s
336 s-vs
410 vs
394 vw, sh
335 vw
295 s
341 s
298 w
415 vw, sh
392 s
407 vs
392 vw, sh
377 s
349 vw
νas(Hg-S)
νs(Hg-S)
220 vs
264 m, sh
350 s
175 m
199 w
244 s
150 s
268 s
160 m
140 m
90 s
203 s
225 m
147 w
129 m
111 m
210 m, sh
120 m, sh
222 m
225 m
δ(C-S-Hg)
156 w, sh
125 m, sh
103 m, b
126 s
131 s
104 m
91 vs
115 s
113 m
91 w, sh
81 vs
110 s
δ(S-Hg-S)
81 sh
69 w
72 m
64 m
84 m, sh
64 vw
89 vs
63 m
81 s
63 vw
89 w
62 vw, sh
82 m
66 vw
88 s
69 m
τ(alkyl)
τ(alkyl)
72 w, sh
50 vw
a b ) broad, s ) strong, m ) medium, w ) weak, sh ) shoulder, v ) very; RE ) Raman.
Interestingly, species of mercury compounds containing the
two different thiolate groups, such as RSHgSR′, could not be
isolated. This result is in general agreement with that found for
the reaction of Hg(SR)2 compounds with organic thiols.18
However, in the presence of even catalytic amounts of diorganyl
disulfide, an equilibrium according to eq 5
a sharp signal a very broad band (retention time interval ) 40-
46.5 min) appears.
Reaching the equilibrium state after approximately 360 h,
the two signals in the tics corresponding to 3 and 7 interestingly
almost disappear (indicating very low concentrations of the
corresponding compounds) and a very broad signal (retention
time interval ≈ 37-47 min) appears instead as exemplified for
eq 7 (Figure 1c). This result suggests a complete equilibration
of the two mercury thiolates.
Hg(SR)2 + Hg(SR′)2{RSSR} 2RSHgSR′
R ) R′ ) alkyl
(5)
All mass spectra obtained from the broad signals at different
retention times are not consistent with a defined mercury
compound, such as 12. However, all these mass spectra suggest
the presence of mercury thiolate species by their fragmentation
signals.
seems to be likely (cf. Figure 1). Our results are specifically
based on investigations of the equilibria summarized in eqs 6
and 7:
Finally, it is possible to disturb the equilibrium state by
addition of a great excess of one of the symmetric disulfides as
shown for eq 7 (Figure 1d,e). The disulfide was added after
384 h. Tics were recorded after additional reaction times of 144
and 312 h, respectively. After 312 h, both the signal of the
starting component 7 and the broad signal completely dis-
appeared and 3 was formed instead (Figure 1e).
C H SHgSC H
15
Hg(SC3H7)2
+ (C7H15S)2 a
+
3
7
7
12
Hg(SC H )
3
C7H15SSC3H7 a
15 2 + (C3H7S)2 (6)
7
7
7 + (C3H7S)2 a 12 + C7H15SSC3H7 a 3 + (C7H15S)2 (7)
Furthermore, it is of great importance to notice that the title
compounds obviously do not exchange the thiolate functional
groups with each other (eq 5) under these particular conditions,
however, in the absence of a diorganyl disulfide. These findings
could be made plausible by accompanying GC experiments.
If the starting components 3 and (C7H15S)2 (eq 6) or 7 and
(C3H7S)2 (eq 7) are employed in stoichiometric amounts the
total ion chromatograms (tics) of the two resulting reaction
mixtures show after 48 h at ambient temperature a new, very
weak signal at a retention time of approximately 45.5 min (inset
in Figure 1a). Its mass spectrum indicates the in situ formation
of compound 12. Additional signals, two in both tics, are
indicative of the corresponding symmetric disulfides and the
asymmetric disulfide C7H15SSC3H7 (retention time ) 27.4 min;
Figure 1a).
After 216 h, the corresponding Hg(SR′)2 compounds can be
clearly associated with another small signal appearing in the
tics at either a retention time of 46.8 min (in the tic according
to eq 6) or a retention time of 32.1 min (in the tic according to
eq 7; Figure 1b). The corresponding compounds can be
identified by their mass spectra as 7 (eq 6) and 3 (eq 7). Besides
some additional signals of decomposition products, the tics of
the reaction mixtures show the signals of all compounds as
expected, except a defined signal for 12 (Figure 1b). Instead of
IR and Raman Spectra. Observed IR and Raman data of
all compounds in the range 4000-800 cm-1 are provided in
Tables S1 and S2 (Supporting Information), those data in the
range of 800-50 cm-1 are listed in Tables 2 and 3. Examples
of IR and Raman spectra in the frequency region of 850-50
cm-1 are shown for 3, 4, 7, and 8 (Figure 2a-d), respectively.
Comparative data are given in Tables S3-S5 (Supporting
Information).
IR and Raman spectra of bis(n-alkanethiolato)mercury(II)
compounds and of related Hg(SR)2 moieties in the solid state
are scarcely discussed.18,21,22a,28,39,41,44-47 In some cases discus-
sions have been even contradictory to each other.21,22a Moreover,
some data21 are in contrast to the results of X-ray structural
analysis,13-16 whereas other data compare very well.22a

982 Inorganic Chemistry, Vol. 40, No. 5, 2001
Hoffmann et al.
Table 3. IR and Raman Frequencies and Assignments of 6-11 in the Region of 800-50 cm-1 a
Hg(SC6H13)2 (6)
Hg(SC7H15)2 (7)
RE IR
Hg(SC8H17)2 (8)
Hg(SC9H19)2 (9)
Hg(SC10H21)2 (10)
Hg(SC12H25)2 (11)
assignment
(proposed)
RE
IR
RE
IR
RE
IR
RE
IR
RE
IR
781 m
781 vw
740 m
719 vs
760 vw
760 vw
732 m, sh 747 vw
718 vs
783 m
728 s, sh
717 vs
752 m
725 m, sh F(CH2)
717 vs
738 m, sh 755 vvw 757 m
728 vs
727 s
726 s
726 vs
724 vs
724 s
724 s
725 s
ν(C-S)
713 w, sh 714 w, sh
716 w, sh
502 vw
480 vw
428 vw
378 vw
366 m
456 m
435 m
456 m
438 m
479 vw
440 m
479 m
442 m
490 vw
449 vw
403 m
380 m
489 vw
448 vw
402 vs
378 vw
489 w
478 vw
489 vw
480 vw
500 vvw
480 vw
425 m
378 s
366 vw, sh
355 m
502 vw
500 vw
δ(C-C-C)
δ(C-C-C)
427 m
372 vw
426 m
373 s
395 m
360 vw
δ(C-C-S)
νas(Hg-S)
νs(Hg-S)
365 vw 365 vs
389 vs
345 vvw
347 vw, sh 348 vs
396 vs
343 vs
381 vw
308 vw
230 w
191 m
345 w, sh 347 m
342 s
381 m
308 s
231 m
189 m
243 vvw
340 vs
339 vvw 375 s
305 vvw 279 w
282 w
329 s
288 m
335 s
332 s
303 s
316 m
253 m
289 vw
308 vw
270 m
224 w
203 vvw
336 m
269 w
222 w
309 vvw 309 w
282 vw
223 vw
206 vw
185 vw
168 vw
133 m
283 vw
222 vw
192 m
201 m
253 m
242 m
210 w
182 vw
159 vvw
139 m
241 w
210 w
δ(C-S-Hg)
183 vw
169 vvw
159 m
133 vw
164 m
132 m
117 w
95 vs
162 w
154 w
152 vw
137 w
118 vw
107 m
90 m
164 m
131 w
105 m, sh
97 vs
168 w
131 w
139 vw 143 w
120 m
105 m
101 vs
102 s
90 m
100 vs
114 m
113 m
100 vw, sh 95 w
87 vs 87 m
97 m
109 m
90 vs
110 m
90 m
δ(S-Hg-S)
85 w, sh 85 m
75 vw, sh 70 vw
85 vs
82 m
86 w, sh 84 m
74 m
τ(alkyl)
τ(alkyl)
65 m
73 w
64 vw, sh 77 w, sh 64 w, sh 70 w, sh 75 m
63 vw
75 m
a b ) broad, s ) strong, m ) medium, w ) weak, sh ) shoulder, v ) very; RE ) Raman.
The frequency window of the Hg-S-stretching vibrations is
approximately 400-180 cm-1. The IR active νas(Hg-S) stretch-
ing is generally located at higher frequencies compared to the
corresponding Raman active νs(Hg-S) stretching modes. The
difference between the two frequencies is approximately an
order of magnitude of 15-40 cm-1 in the case of linear and
tetrahedral coordination of mercury. The position of Hg-S
stretching modes strongly depends on the coordination number
of mercury, where only atoms which are strongly bonded to
mercury (average bond length below ca. 2,8 Å) are of influence
on the relevant vibrational modes.22,39 Increasing coordination
from two to four corresponds with a decrease and with splittings
of Hg-S frequencies and modes, respectively. This finding is
nowadays generally accepted. The coordination number of
mercury correlates with the Hg-S frequencies not only for the
discussed compounds, but also for related mercury thiolate
compounds, as is discussed and well-documented for a series
of RSHgX compounds.22b
compounds to exhibit an almost linear S-Hg-S skeleton with
a primary coordination of two for mercury.13-16,18 Accordingly,
two Hg-S stretching modes can be expected in the vibrational
spectra. These IR active νas(Hg-S) and Raman active νs(Hg-
S) stretchings can be assigned without any doubt for 1, 2, 5, 6,
and 8 (Figure 2d), being the only acceptable pairs of modes
with satisfying intensity in the relevant frequency region. The
presence of weak forbidden IR and Raman counterparts for the
majority of these bands support the assignment. For 10 and 11
no particular vibrational coupling with ν(Hg-S) will be
expected in comparison to 8. Therefore, suitable modes at 335
and 355 cm-1 for 10, as well as 332 and 347 cm-1 for 11, are
assigned to the ν(Hg-S) stretchings (Table 3). Compound 4
(Figure 2b) does not cause ν(Hg-S) stretchings comparable to
the other title compounds because of its sulfur-bridged crystal
structure, which varies from the other compounds,thus exhibiting
the coordination number four for mercury.17 For the remaining
compounds 3 (Figure 2a), 7 (Figure 2c), and 9, two pairs of
bands can alternatively be considered for the ν(Hg-S) stretching
modes (Tables 2 and 3). We ascribe the pairs of vibrations
situated at the higher frequencies to the ν(Hg-S) stretchings
of compounds 3, 7, and 9, respectively. A suitable explanation
for this assignment can be given with the comparable behavior
of the ν(S-S) stretchings of di-n-alkyl disulfides.57 The deriva-
tives with odd-numbered carbon chains exhibit these stretching
modes at higher frequencies compared to those derivatives with
even-numbered carbon chains. This behavior can be made
plausible by the different packing of even and odd numbered
alkyl groups, as suggested for long-chained paraffins.58 In the
special case of compound 3, the proposed assignment can be
additionally supported by taking into consideration that forbid-
den IR and Raman counterparts are showing up as weak bands.
Generally, homoleptic thiolate complexes of mercury show
a
considerable variation in their coordination geom-
etry,13-18,27,29,39,47-55 but the factors determining these geom-
etries are not yet clear.56 X-ray structural analysis showed most
of the hitherto investigated bis(n-alkanethiolato)mercury(II)
(44) Iwasaki, N.; Tomooka, J.; Toyoda, K. Bull. Chem. Soc. Jpn. 1974,
47, 1323.
(45) Canty, A. J.; Kishimoto, R. Inorg. Chim. Acta 1977, 24, 109.
(46) Perchard, C.; Zuppiroli, G.; Gouzerh, P.; Jeannin, Y.; Robert, F. J.
Mol. Struct. 1981, 72, 119.
(47) Barrera, H.; Bayo´n, J. C.; Gonza´lez-Duarte, P.; Sola, J.; Vin˜as, J. M.;
Brianso´, J. L.; Brianso´, M. C.; Solans, X. Polyhedron 1982, 1, 647.
(48) Blower, P. J.; Dilworth, J. R. Coord. Chem. ReV. 1987, 76, 121.
(49) Taylor, N. J.; Carty, A. J. J. Am. Chem. Soc. 1977, 99, 6143.
(50) Alsaadi, B. M.; Sandstro¨m, M. Acta Chem. Scand., Ser. A 1982, 36,
509.
(51) Christou, G.; Folting, K.; Huffman, J. C. Polyhedron 1987, 3, 1247.
(52) Wang, S.; Fackler, jun., J. P. Inorg. Chem. 1989, 28, 2615.
(53) Block, E.; Brito, M.; Gernon, M.; McGowty, D.; Kang, H.; Zubieta,
J. Inorg. Chem. 1990, 29, 3172.
(54) Casals, I.; Gonza´lez-Duarte, P.; Clegg, W. Inorg. Chim. Acta 1991,
184, 167.
(56) Bowmaker, G. A.; Dance, I. G.; Harris, R. K.; Henderson, W.; Laban,
I.; Scudder, M. L.; Oh, S.-W. J. Chem. Soc., Dalton Trans. 1996,
2381.
(57) Steinfatt, I.; Hoffmann, G. G.; Brouwer, L.; Menzel, F.; Brockner,
W. Phosphorus, Sulfur Silicon 1998, 134/135, 31.
(58) Beyer, H. Lehrbuch der Organischen Chemie, 18th ed.; S. Hirzel:
Stuttgart, 1978; pp 55-56.
(55) Noh, D.-Y.; Underhill, A. E.; Hursthouse, M. B. Chem. Commun. 1997,
2211.

Bis(n-alkanethiolato)mercury(II) Compounds
Inorganic Chemistry, Vol. 40, No. 5, 2001 983
Figure 3. Correlation of νs(Hg-S) and νas(Hg-S) frequencies to the
chain length of the alkyl substituents of the title compounds.
the exception of 4); on the other hand, for those compounds
with an odd-numbered alkyl chain, the ν(Hg-S) stretchings are
slightly increasing with an increasing alkyl chain number
(however, 3 is an exception if the higher modes at 395 and 403
cm-1 are considered). These results can clearly be seen in Figure
3. Finally, the position of the discussed ν(Hg-S) stretchings
for 1-3 and 5-11 at high frequencies is indicative of a
coordination of two at the central mercury.28,56
Other modes of significance are the δ(S-Hg-S) bendings.
Generally, the difference between the IR-active δas(S-Hg-S)
and the Raman-active δs(S-Hg-S) mode can be expected to
be small. It is unfortunate, but especially in the case of these
compounds, only for 1 are IR-active bendings discussed and
assigned at 126 and 95 cm-1 44
δ(S-Hg-S) bendings are given in the region between ap-
proximately 170 and 90 cm-1 39,59
With the exception of 4, all
.
For some related complexes
.
title compounds show medium-strong bands within the fre-
quency window reaching from 115 to 90 cm-1, which can be
attributed to these δ(S-Hg-S) bendings (Tables 2 and 3).
Skeletal bending modes δ(C-S-Hg) are expected to occur
below approximately 250 cm-1, however, at significantly higher
frequencies than the δ(S-Hg-S) bendings. For 1 and 2 Raman-
active modes have been suggested in the region from 175 to
150 cm-1 21,44
derivative, this mode as well as its IR-active counterpart are
given at 159 cm-1 39
The IR-active counterpart for 1 has been
assigned to 198 cm-1 44
In our opinion, a detailed assignment
.
For the corresponding cyclohexanethiolato
.
.
of these modes still seems to be highly speculative. Therefore,
our assignments presented in Tables 2 and 3 have to be seen as
only tentative. In some of the previous studies other modes of
interest, such as ν(C-S), δ(C-C-C), and δ(C-C-S), as well
as rockings, such as F(CH2), are reported.21,22a,39,44,45,60,61 These
modes occur in the region from approximately 800 to 350 cm-1
.
Thus, it has to be taken into account that they may overlap each
other, and in addition, some of these modes may overlap the
ν(Hg-S) stretchings, too. Appropriate assignments are given
for all compounds in Tables 2 and 3 without further discussion.
Bands observed in the region from 750 to 650 cm-1 can be
assigned definitely to CH2 rocking and C-S stretching vibra-
tions (Tables 2 and 3).21,44,57 Especially in case of longer chain
substituents, very low-frequency bands may be caused by so-
called longitudinal accordion motions (LAM modes) as for
Figure 2. Infrared (upper) and FT-Raman (lower) spectra of 3 (2a), 4
(2b), 7 (2c), and 8 (2d) at room temperature in the region 850-50
cm-1: (a) CsI, pellet and (b) PE Nujol.
On the other hand, the bands at 330 and 336 cm-1 have to be
kept in mind for these modes, too, as they are reasonably
positioned in the relevant region. Comparing the compounds
with an even-numbered alkyl chain, as well as those compounds
with an odd-numbered alkyl chain, with each other, one can
observe a slight decrease of the ν(Hg-S) stretchings going along
with an increasing chain length of the ligand for those
compounds with an even-numbered alkyl chain (however, with
(59) Bowmaker, G. A.; Dance, I. G.; Dobson, B. C.; Rogers, D. A. Aust.
J. Chem. 1984, 37, 1607.
(60) Biscarini, P.; Fusina, L.; Nivellini G. Spectrochim. Acta 1980, 36A,
593.
(61) Fergusson, J. E.; Loh, K. S. Aust. J. Chem. 1973, 26, 2615.

984 Inorganic Chemistry, Vol. 40, No. 5, 2001
Hoffmann et al.
Table 4. GC/MS Data, Mass Spectra, and the Main Fragmentation Pattern of 1-11 Together with Their Decomposition Products, the
Corresponding Di-n-alkyl Disulfides (CnH2n+1)2S2 for n ) 1-10, 12
fragmentation (main peaks)
retention
(min)
a
no.
formula
(CH3S)2
MW
M+ a CH2SHgSHa CH2SHgSRa RSHgSHa RSHga Hg(SH)2 HgSa Hga RSSRb RSSH RS
1
94.20
3.4
25.7
9.7
-
296
-
324
-
352
-
380
-
408
-
436
-
464
-
492
-
-
281
-
281
-
281
-
281
-
281
-
281
-
281
-
281
-
-
285
-
309
-
323
-
337
-
351
-
365
-
379
-
393
-
-
282
-
296
-
310
-
324
-
338
-
352
-
366
-
380
-
-
249
-
263
-
277
-
291
-
305
-
319
-
333
-
347
-
-
268
-
268
-
268
-
268
-
268
-
268
-
268
-
268
-
-
-
94
94
79c
79c
94
47
Hg(SCH3)2
(C2H5S)2
Hg(SC2H5)2
(C3H7S)2
Hg(SC3H7)2
(C4H9S)2
Hg(SC4H9)2
(C5H11S)2
Hg(SC5H11)2
(C6H13S)2
Hg(SC6H13)2
(C7H15S)2
Hg(SC7H15)2
(C8H17S)2
Hg(SC8H17)2
(C9H19S)2
294.79
234 202
-
234 202
-
234 202
-
234 202
-
234 202
-
234 202
-
234 202
-
234 202
47
2
3
4
5
6
7
8
9
122.252
322.842
150.304
350.894
178.356
378.946
206.408
406.998
234.46
-
122
122
150
150
178
178
206
206
234
234
262
262
290
290
318
66d
66d
66d
66d
28.7
16.1
32.1
22.5
36.4
27.3
40.4
31.8
43.7
36.1
46.8
40.0
49.9
43.5
94
-
108
108
122
122
136 103
136 103
150 117
150 117
164 131
164 131
178 145
178 145
192 159
-
-
18
-
435.05
262.512
463.102
290.564
491.154
318.616
519.206
346.668
-
-
-
-
-
-
-
-
e
Hg(SC9H19)2
-
10 (C10H21S)2
Hg(SC10H21)2 547.258
11 (C12H25S)2
46.8
-
-
-
-
-
-
-
-
-
-
-
-
346
402
206 173
234 201
e
-
402.772
52.6
e
Hg(SC12H25)2 603.362
-
a Main peak of the isotope pattern of mercury. b 100% signal. c RSS. d HSSH. e Decomposition of the mercury compound on the column.
example discussed for fatty acids.62a and other suitable
compounds.62b
spectra of 4 reveal very broad IR as well as Raman bands at
250 and 220 cm-1, respectively (Figure 2b). In this case, as for
1, we support the data already presented.21 In addition, the IR
data are in accordance with those data given elsewhere, however,
without presenting defined assignments.41
With respect to the already published data for 1,21,22a,44 2,21,22a
3,21 and 4,21,41 the following conclusions can be drawn. For 1
(Table S3) a reasonable assignment supported by a vibrational
analysis is already presented.44 Our frequency values are in
accordance with these data; moreover, we strictly follow the
given assignments. Especially for the ν(Hg-S) stretchings,
additional data are available and are all in accordance with both
the above-mentioned values and the vibrational analysis.21,22a
Our spectral data of 2 (Table S4) harmonize well with those
already presented.22a Moreover, in accordance with the given
frequencies, we assign the ν(Hg-S) stretchings to νas ) 407
cm-1 and νs ) 392 cm-1, respectively. However, these
assignments are contradictory to other data,21 where the assigned
frequencies for the ν(Hg-S) stretchings are obviously far too
low, considering that in 2 mercury has a coordination number
of two. In addition, the published spectral data are obviously
incomplete for the lower frequency region.21,22a In our opinion,
the same discussion can be easily transferred to 3. Assignments
of the modes of this compound already exist.21 However, once
more, the frequencies of the ν(Hg-S) stretchings are assigned
far too low (Table S4).21 Moreover, the assignment is in contrast
to the crystal structure determination discussed for 3, presenting
the coordination number two for mercury.13 Therefore, we
preferably suggest the bands at 395 and 402 cm-1 to these
stretchings. However, keep in mind that it also remains possible
to assign the frequencies at 330 and 336 cm-1 to these
stretchings, especially as they would almost perfectly fit in the
plot for the compounds with an odd-numbered alkyl chain
(Figure 3).
Identification of Hg(SR)2 by Means of Gas Chromatog-
raphy-Mass Spectrometry (GC/MS). GC/MS investigations
clearly reveal the title compounds to be monomeric in the gas
phase. As expected, they easily undergo decomposition at
elevated temperatures. The main decomposition products are
mercury and the corresponding dialkyl disulfides as is revealed
in the obtained tics. For those mercury compounds with a lower
molecular weight (up to 8), the decomposition products can be
identified in both the tics and the mass spectra of the parent
compounds, in the latter as the main fragmentation products.
Moreover, the signal intensities of the bis(n-alkanethiolato)-
mercury(II) compounds in the tics are significantly decreasing
with increasing molecular weight of the mercury compound,
whereas the corresponding signals of the decomposition products
are increasing. This general finding is due to the enhanced
decomposition of these compounds, caused by their progres-
sively longer retention times on the GC column. Compounds
9-11 already decompose on the GC column. This is the reason
why only the corresponding decomposition products (mainly
the dialkyl disulfides and in a minor amount the dialkyl sulfides)
can be detected for these compounds in the tics of GC/MS
recordings; however, no signal of the parent compound is seen.
The results are in agreement with the thermochemical behavior
of the title compounds.18,33,38,63-67 The fragmentation of all
mercury compounds is given in Table 4.
Finally and as already mentioned, for 4 surprisingly a four-
coordinated central mercury could be clearly established by
X-ray structural investigations.13,17 Accordingly, ν(Hg-S)
stretchings are situated at significantly lower frequencies in the
corresponding frequency window. That is the reason the spectra
of this particular compound cannot be compared with those of
all other compounds investigated (cf. Figure 3 and Table S5).
Remarkably and in contrast to all other title compounds, the
(62) (a) Vergottin, G.; Fleury, G.; Moschetto, I. In AdVances in Infrared
and Raman Spectroscopy; Clark, R. J. H., Hester, R. E., Eds.;
Heyden: London, 1978; Vol. 4, p 195. (b) Zerbi, G. (ed.) Modern
Polymer Spectroscopy; Wiley-VCH: Weinheim, 1999; pp. 159-163.
(63) Dreher, E.; Otto, R. Liebigs Ann. Chem. 1870, 154, 178.
(64) Otto, R. Ber. Dtsch. Chem. Ges. 1880, 13, 1289.
(65) Lecher, H. Ber. Dtsch. Chem. Ges. 1915, 48, 1425.
(66) Biscarini, P.; Fusina, L.; Nivellini, G. J. Chem. Soc., Dalton Trans.
1972, 1921.
(67) Ktenas, T. B.;. Taylor, M. D J. Thermal Anal. 1982, 25, 563.

Bis(n-alkanethiolato)mercury(II) Compounds
Inorganic Chemistry, Vol. 40, No. 5, 2001 985
Conclusion
tics, the corresponding mass spectra of which show a molecular
ion R′SHgSR+ with the mercury isotope pattern.
Hg(SCnH2n+1 2 for n ) 1-10, 12 (compounds 1-11,
)
respectively) have been prepared from HgI2 and n-alkanethiol
using N(C2H5)3 as an auxiliary base. An elegant alternative route
is given with the exchange reaction of mercury(II) chloride with
trimethylsilyl organyl sulfides. IR and Raman data indicate the
mercury compounds to be monomeric with an almost linear
S-Hg-S skeleton in the solid state with the exception of 4,
the spectra of which exhibit the compound to be four coordi-
nated at the central mercury. The title compounds easily
exchange the thiolate functional groups with corresponding
diorganyl disulfides already at ambient temperature, however
in a complicated exchange process including an equilibration
of the symmetric diorganyl disulfides with their asymmetric
counterpart. Interestingly, asymmetric R′SHgSR moieties cannot
be practically isolated. However, GC/MS investigations show
that there is at least evidence for these compounds in the in
situ reaction mixtures, indicated by very weak signals in the
Acknowledgment. This work was supported by the Minis-
terium fu¨r Wissenschaft und Kultur (MWK) of Lower Saxony,
Germany. I.S. is grateful for a fellowship funded by the MWK
of Lower Saxony. G.G.H. acknowledges the financial support
of the Fonds der Chemischen Industrie. We thank K. Bode and
A. Strohschein for recording the vibrational spectra, E. Ro¨mer
for recording the GC/MS spectra, and Dr. B. Essiger for DSC
and TG measurements.
Supporting Information Available: Complete lists of IR and
Raman data for all compounds (Tables S1 and S2). Comparison of
literature data of the IR and Raman spectra of compounds 1-4 (Tables
S3-S5). This material is available free of charge via the Internet at
http://pubs.acs.org.
IC000638B