Formation of extended 1D coordination polymers in tetrathioether complexes of mercury(II): Effect of the organic substituents on the crystal structures of {Si(CH2SR)4}HgBr2 (R = Me, Ph)

Article abstract of DOI:10.1016/j.inoche.2005.02.008

Two novel one-dimensional (1D) coordination polymers of stoichiometry [{Si(CH₂SR)₄}HgBr₂]_n (R = Me, 2a; R = Ph, 2b) have been prepared by treatment of HgBr₂ with the functionalized silanes Si(CH₂

Full text of DOI:10.1016/j.inoche.2005.02.008

Inorganic Chemistry Communications 8 (2005) 479–482
www.elsevier.com/locate/inoche
Formation of extended 1D coordination polymers in
tetrathioether complexes of mercury(II): Effect of
the organic substituents on the crystal structures of
{Si(CH2SR)4}HgBr2 (R = Me, Ph)
a
a
a,
b
Harmel N. Peindy , Fabrice Guyon , Michael Knorr *, A. Brooke Smith ,
b
Jamshaid A. Farouq , Susana A. Islas , Daniel Rabinovich
b
b,
*
,
c
James A. Golen , Carsten Strohmann
d,
*
a
´ ´ ´ ´
Laboratoire de Chimie des Materiaux et Interfaces, Universite de Franche-Comte, Faculte des Sciences et des Techniques, 16,
Route de Gray, 25030 Besanc¸on, France
b
Department of Chemistry, The University of North Carolina at Charlotte, 9201 University City Boulevard, Charlotte, NC 28223, USA
c
Department of Chemistry and Biochemistry, University of Massachusetts – Dartmouth, North Dartmouth, MA 02747, USA
d
Institut fu¨r Anorganische Chemie der Universita¨t Wu¨rzburg, Am Hubland, D-97074 Wu¨rzburg, Germany
Received 24 January 2005; accepted 27 February 2005
Available online 13 April 2005
Abstract
Two novel one-dimensional (1D) coordination polymers of stoichiometry [{Si(CH2SR)4}HgBr2]n (R = Me, 2a; R = Ph, 2b) have
been prepared by treatment of HgBr2 with the functionalized silanes Si(CH2SR)4 (R = Me, 1a; R = Ph, 1b) acting as tetradentate
thioether ligands. The extended structures result from intermolecular Hg–S interactions linking the monomeric {Si(CH2SR)4}HgBr2
units, as established for 2a,b using single-crystal X-ray diffraction. The effective coordination around the Hg atoms in both com-
pounds is best described as distorted octahedral.
Ó 2005 Elsevier B.V. All rights reserved.
Keywords: Mercury; Silicon; Thioether complexes; Coordination polymers; Silanes
We have recently reported the synthesis of the
bidentate and tridentate thioethers R4 ꢀ nSi(CH2SR)n
(n = 2, 3; R = Me, Ph) and characterized a wide vari-
ety of complexes in which they act as either terminal
[1–5] or bridging ligands [6,7]. The latter are particu-
larly interesting since flexible multidentate ligands
have the ability to generate diverse coordination net-
works with potential applications as functional mate-
rials [8–10] but the use of polythioethers in such
context has received little attention [11–16]. Contin-
uing our studies on multidentate thioethers, we set
out to synthesize and evaluate the coordinative prop-
erties of the tetrathioether ligands Si(CH2SR)4
(R = Me, 1a; R = Ph, 1b). In this regard, Goodall
[17]
*
Corresponding authors. Tel.: +33 3 81 66 62 70; fax: +33 3 81 66 64
38 (M. Knorr).
E-mail addresses: michael.knorr@univ-fcomte.fr (M. Knorr),
drabinov@email.uncc.edu (D. Rabinovich), mail@carsten-strohmann.
de (C. Strohmann).
1387-7003/$ - see front matter Ó 2005 Elsevier B.V. All rights reserved.
doi:10.1016/j.inoche.2005.02.008

480
H.N. Peindy et al. / Inorganic Chemistry Communications 8 (2005) 479–482
pentane
- 4LiCl
RS
RS
SiCl4 + 4 LiCH2SMe
Si(CH2SMe)4
SR
SR
R = Me (1a)
R = Ph (1b)
Si
Scheme 1.
The molecular structures of both 2a and 2b were deter-
mined by single-crystal X-ray diffraction.3 The complexes
present in the solid state extended structures in which
fairly linear HgBr2 moieties are connected by doubly
bidentate chelating thioether ligands (Figs. 1 and 2).
Interestingly, whereas the methyl groups in 2a are ar-
ranged in an anti fashion, all the phenyl substituents in
2b adopt a parallel orientation. The mercury centers in
both complexes are in distorted octahedral environments,
with the deviation from the ideal geometry being more
pronounced in the case of 2b. In this regard, whereas all
the cis S–Hg–S and S–Hg–Br angles in 2a are in the
approximate range 84–96°, the corresponding values in
2b span the range 78–99°. Similarly, the deviation from
linearity of the Br–Hg–Br angle in 2b [170.70(2)°] is more
evident than in 2a [176.73(2)°], a situation that appears to
be reflected also in the moderately shorter Hg–Br bond
investigated almost 40 years ago the coordination chem-
istry of the related tetrakis[(alkylthio)methyl]methanes
C(CH2SR)4 (R = Bun, Ph) towards palladium, platinum
and mercury. In particular, the Hg(II) ion formed dinu-
clear complexes [X2Hg{C(CH2SBun)4}HgX2] (X = Cl,
Br, I) having doubly bidentate chelating ligands,
whereas no analogous reaction was observed for the
phenyl-substituted thioether ligand. Interested in inves-
tigating the effect on structure and reactivity of replacing
the central carbon atom in C(CH2SR)4 by silicon, we re-
port herein the synthesis of 1a (that of 1b has already
been published [18a]) and the reactivity of both ligands
towards HgBr2.
˚
The tetrathioether Si(CH2SMe)4 (1a) was easily syn-
thesized, following a procedure similar to that used to
prepare MeSi(CH2SMe)3 [1], by reacting tetrachlorosi-
lane with 4 molar equivalents of LiCH2SMe (Scheme
1). Following vacuum distillation (b.p. = 127–130 °C at
0.29 Torr), 1a was isolated in pure form as a pale yellow
liquid in ca. 65% yield.1
lengths observed in 2b [2.4521(7) and 2.4540(6) A] relative
˚
to those in 2a [2.5147(5) A]. The presence of a crystallo-
graphically imposed mirror plane which bisects the
Br–Hg–Br and C–Si–C angles in 2a leads to the observa-
tion of only two unique Hg–S bond lengths [2.955(1) and
3.048(1) A]. In the case of 2b, although the two intramo-
lecular Hg–S bond distances are very similar [2.989(2)
˚
˚
and 2.994(2) A], the two intermolecular interactions are
˚
significantly longer [3.201(2) and 3.204(2) A], a situation
which is arguably a consequence of the lower Lewis basi-
city of the SPh vs. SMe groups. It is also interesting to note
that all of these Hg–S bond lengths are considerably
The complexes [{Si(CH2SR)4}HgBr2] (R = Me, 2a;
R = Ph, 2b) were readily prepared by allowing mer-
cury(II) bromide to react with equimolar amounts of
the corresponding thioethers (Scheme 2) and were iso-
lated as white, air-stable solids in 55–80% yield. They
are both soluble in chlorinated hydrocarbons and were
characterized by a combination of analytical and spec-
troscopic techniques.2 Their 1H NMR spectra (in
CDCl3) exhibit singlet resonances for the methylene
protons (d 2.20 and 2.68 ppm for 2a and 2b, respec-
tively), both of which are only slightly downfield
shifted (ca. 0.15 ppm) relative to the free ligands in
the same solvent. More importantly, the presence of
only one signal for the four methylene groups in each
case (down to 253 K for 2b) is consistent with the
presence of highly fluxional (i.e., labile) systems in
solution.
˚
longer than the corresponding values (ca. 2.5–2.9 A) typ-
ically observed in a variety of Hg(II) thioether complexes,
including polymeric species [19–30].
In conclusion, we have demonstrated that, unlike
C(CH2SPh)4, the tetrathioether silane Si(CH2SPh)4 coor-
dinates to HgBr2 and that both 2a and 2b display one-
dimensional extended structures in the crystalline state.
However, whereas the intra- and intermolecular Hg–S
interactions in 2a are almost identical, the intermolecular
Hg–S contacts in 2b are markedly weaker than the intra-
molecular ones. Our systematic studies on the coordina-
tion chemistry of Si(CH2SR)4 (R = Me, Ph) and
Ge(CH2SR)4 [18b] towards other cadmium and mercury
halides will be published elsewhere in the near future.
1
Selected data for 1a: NMR data (in C6D6): 1H d 1.88 (s, 12 H,
CH3), 2.04 (s, 8 H, CH2); 13C d 16.4 (t, JC–H = 131, 4 C, CH2), 20.0
1
(q, 1JC–H = 138, 4 C, CH3). Anal. Calcd. for C8H20S4Si: C, 35.2; H, 7.4;
S, 47.0. Found: C, 35.7; H, 7.1; S, 45.7%.
Crystal data for 2a (at 100 K): monoclinic, C2/c, a = 14.4802(11),
3
3
˚
˚
b = 8.9207(6), c = 14.1158(10) A, b = 107.963(1)°, V = 1734.5(2) A ,
Z = 4; structure refined by full-matrix least-squares on F2 to give final
indices R1 = 0.0270 and wR2 = 0.0681. Crystal data for 2b (at 173 K):
2
Selected data for 2a: NMR data (in CDCl3) 1H d 2.20 (s, 8 H,
CH2), 2.29 (s, 12 H, CH3); 13C d 16.9 (t, JC–H = 133, 4 C, CH2), 21.3
1
(q, 1JC–H = 141, 4 C, CH3). Anal. Calcd. for C8H20Br2HgS4Si: C, 15.2;
H, 3.2. Found: C, 15.2; H, 3.2%. Selected data for 2b: NMR data (in
CDCl3) 1H d 2.68 (s, 8 H, CH2), 7.25–7.37 (m, 20 H, C6H5). Anal.
Calcd. for C28 H28Br2HgS4Si: C, 38.2; H, 3.2. Found: C, 38.5; H, 3.4%.
triclinic, P1, a = 9.3386(19), b = 13.323(3), c = 13.879(3) A,
˚
ꢀ
3
˚
a = 62.28(3)°, b = 89.62(3)°, c = 79.84(3)°, V = 1499.1(5) A , Z = 2;
structure refined by full-matrix least-squares on F2 to give final indices
R1 = 0.0364 and wR2 = 0.0774.

H.N. Peindy et al. / Inorganic Chemistry Communications 8 (2005) 479–482
481
MeOH, RT
R
R = Me, ca. 80%
RS
RS
Br
Br
S
S
Hg
HgBr2 + Si(CH2SR)4
Si
toluene, reflux
R
R = Ph, ca. 55%
Scheme 2.
C3'
C3'''
S2'''
C4'''
S1'''
S1'
C1'
Br1'
Hg1
Br1
Br1'''
Hg1'
Br1''
C2'
Si1
C2
S2'
C2'''
C1'''
Si1'
C2''
C1
C1''
S1''
S2
C4''
S1
S2''
C3''
C3
˚
Fig. 1. Crystal structure of [{Si(CH2SMe)4}HgBr2] (2a). Selected bond lengths (A) and angles (°): Hg–S(1) 2.9549(10), Hg–S(2) 3.0481(10), Hg–Br(1)
2.5147(5), and Br(1)–Hg–Br(1)0 176.729(17), Br(1)–Hg–S(1) 92.29(2), Br(1)–Hg–S(1)0 90.12(2), Br(1)–Hg–S(2)000 89.64(2), Br(1)–Hg–S(2)00 87.92(2),
S(1)–Hg–S(1)0 85.09(4), S(1)0–Hg–S(2)00 177.96(3), S(1)–Hg–S(2)00 95.57(3), S(2)00-Hg-S(2)000 83.84(4).
S1
S1'
S3'
S4'
Br2
Br1
Br2'
Hg'
C1
C1'
Si'
C3'
S3
S4
Si
C3
Hg
C4
C4'
C2
C2'
Br1'
S2'
S2
˚
Fig. 2. View of the crystal structure of [{Si(CH2SPh)4}HgBr2] (2b) along the x-axis. Selected bond lengths (A) and angles (°): Hg–S(1) 2.9888(17),
Hg–S(2) 2.9935(15), Hg–S(3) 3.2013(15), Hg–S(4) 3.2037(17), Hg–Br(1) 2.4540(6), Hg–Br(2) 2.4521(7), and Br(1)–Hg–Br(2) 170.695(15), Br(1)–Hg–
S(1) 94.77(4), Br(1)–Hg–S(2) 92.33(3), Br(1)–Hg–S(3)0 78.32(4), Br(1)–Hg–S(4)0 94.42(4), Br(2)–Hg–S(1) 92.06(4), Br(2)–Hg–S(2) 94.73(4), Br(2)–
Hg–S(3) 94.42(4), Br(2)–Hg–S(4)0 78.55(4), S(1)–Hg–S(2) 83.43(4), S(1)–Hg–S(3)0 98.97(4), S(1)–Hg–S(4)0 170.50(3), S(2)–Hg–S(3)0 170.48(3), S(2)–
Hg–S(4)0 98.59(4), S(3)0–Hg–S(4)0 80.57(4).
Acknowledgements
Appendix A. Supplementary data
We are grateful to the Deutschen Forschungsgeme-
`
Crystallographic data for the structural analyses of
compounds 2a and 2b have been deposited with the
Cambridge Crystallographic Data Centre (CCDC No.
260622 and 260623, respectively). Copies of this infor-
mation may be obtained free of charge from: The direc-
tor, CCDC, Union Road, Cambridge, CB2 IEZ, UK
inschaft and the French Ministere de la Recherche et
Technologie for financial support. D.R. also thanks
the Camille and Henry Dreyfus Foundation, Inc. for a
Henry Dreyfus Teacher-Scholar Award and Research
Corporation for a Cottrell College Science Award.

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H.N. Peindy et al. / Inorganic Chemistry Communications 8 (2005) 479–482
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