Organo(organooxo)mercury(II) chemistry - Synthesis and structure of methyl(phenoxo)mercury(II)

Article abstract of DOI:10.1139/V05-219

Methyl(phenoxo)mercury(II) may be obtained from the reaction of methyl(chloro)mercury(II) with silver(I) oxide, followed by addition of phenol. The dominant motif of the structure is a pair of independent MeHgOPh aggregates (Hg-C,O 2.05(2) A, 2.06(1) A (x2); C-Hg-O 176.6(5)°, 176.3(5)°) loosely associated about a quasi-inversion centre by Hg...O interactions (2.702(9) A, 2.719(9) A) to form a dimer (Hg-O-Hg′ 106.0(4)°, 106.5(4)°; O-Hg-O′ 73.0(3)°, 72.6(3)°), the dimer stacking up the short crystallographic c axis (= 6.914(1) A′) at spacings c/2. Vibrational spectroscopic studies are insensitive to the associative interactions.

Full text of DOI:10.1139/V05-219

77
Organo(organooxo)mercury(II) chemistry — Synthesis
and structure of methyl(phenoxo)mercury(II)1
Allan J. Canty, Janette W. Devereux, Brian W. Skelton, and Allan H. White
Abstract: Methyl(phenoxo)mercury(II) may be obtained from the reaction of methyl(chloro)mercury(II) with silver(I)
oxide, followed by addition of phenol. The dominant motif of the structure is a pair of independent MeHgOPh aggre-
gates (Hg—C,O 2.05(2) Å, 2.06(1) Å (x2); C-Hg-O 176.6(5)°, 176.3(5)°) loosely associated about a quasi-inversion
centre by Hg···O interactions (2.702(9) Å, 2.719(9) Å) to form a dimer (Hg-O-Hg′ 106.0(4)°, 106.5(4)°; O-Hg-O′
73.0(3)°, 72.6(3)°), the dimer stacking up the short crystallographic c axis (= 6.914(1) Å) at spacings c/2. Vibrational
spectroscopic studies are insensitive to the associative interactions.
Key words: mercury, methylmercury, organomercury, structure, aryloxide, phenoxide.
Résumé : On peut obtenir du méthyl(phénoxo)mercure(II) par réaction du méthyl(chloro)mercure(II) avec de l’oxyde
d’argent(I), suivie d’une addition de phénol. Le motif dominant de la structure est une paire d’agrégats indépendants de
MeHgOPh (Hg—C,O 2,05(2) Å, 2,06(1) Å (x2); C-Hg-O 176,6(5)°, 176,3(5)°) faiblement associés autour d’un centre
de quasi-inversion par des interactions Hg···O (2,702(9) Å, 2,719(9) Å) qui permettent de former le dimère (Hg-O-
HgN 106,0(4)°, 106,5(4)°; O-Hg-ON 73,0(3)°, 72,6(3)°) qui s’empile le long de l’axe cristallographique c (= 6,914(1) Å)
à des distances de c/2. Les études spectroscopiques vibrationnelles sont insensibles aux interactions associatives.
Mots clés : mercure, méthylmercure, organomercure, structure, aryloxyde, phénolate.
[Traduit par la Rédaction] Canty et al 80
Introduction
(2.75 Å) interactions (5). A weak intermolecular Hg···O in-
teraction is also observed in PhHgOC6H3ClBr (2.85(2) Å),
although the molecule is essentially a monomer with C-Hg-
O 174(1)°, where this angle is opposite a weak intramolecu-
lar Hg···Cl interaction (3.03 Å) (3). Noting the additional
weak interactions present in these structures and the marked
tendency for unsymmetrical coordination geometries for
monoorganomercury(II) complexes, geometries for 2–4 are
drawn to illustrate this behaviour, and additional weak inter-
actions could be anticipated for monomers (1) (Scheme 1).
Archetypal examples of unsymmetrical geometry are illus-
trated by the 2,2′-bipyridine complex [MeHg(bpy)]NO3,
which has C-Hg-N 164(1)°, Hg—N 2.24(3) Å, Hg···N
2.43(3) Å (10); the D,L-penicillamine complex MeHgSCMe2-
CH(CO2)NH2HgMe, which has C-Hg-N 168.1°, Hg—N
2.216(5) Å, Hg···O 2.708(4) Å (11); and the closely related
D,L-selenocysteine complex MeHgSeCH2CH(CO2)NH3·H2O,
which has C-Hg-Se 177.8(11)°, with associated more distant
approaches Hg···O 2.93(2) Å and Hg···Se 3.737(4) Å (12).
In view of the lack of structural characterization for
fundamental aryloxo complexes, the propensity for
organomercury(II) compounds to adopt unusual geometries
for mercury, the various structures proposed on the basis of
physical and spectroscopic studies (1–3), and the structure
The coordination chemistry of monoorganomercury(II)
complexes has been reviewed (1, 2); for arylalkoxides and
aryloxides, structural studies are limited to the early study of
the 4-bromo-2-chlorophenoxo complex PhHgOC6H3ClBr (3, 4),
although the structure of
a trimethylsiloxo complex,
MeHgOSiMe3, has also been described (5). Vibrational
spectroscopic data have been interpreted in terms of
monomeric structures for MeHgOPh and PhHgOPh in both
the solid state and in dichloromethane (1 in Scheme 1), con-
sistent with osmometric studies in dichloromethane (6).
However, in the less polar solvent benzene, ebullioscopic
studies indicate that PhHgOPh and relatives PhHgOR′ (R′ =
Me, i-Pr, s-Bu, CMe2Ph) are associated and consistent with
a monomer (1) – dimer (2) equilibrium (7), and it has also
been suggested that PhHgOPh can adopt both dimeric (2)
and trimeric (3) forms (8). Vibrational spectra are also con-
sistent with a dimeric structure in the solid state for
PhHgOR′ (R′ = Me, Et) (6). The complex MeHgOSiMe3 is
monomeric in benzene (osmometry) (9), and in the solid
state an incomplete X-ray structure determination (280
“observed” reflections, R = 0.21) indicated a tetrameric
structure (4) with short Hg—O (2.11 Å) and long Hg···O
Received 17 January 2005. Published on the NRC Research Press Web site at http://canjchem.nrc.ca on 14 February 2006.
In honour of our colleague and friend Arthur J. Carty.
A.J. Canty2 and J.W. Devereux. School of Chemistry, University of Tasmania, Hobart, Tasmania, Australia 7001.
B.W. Skelton and A.H. White. Chemistry M313, University of Western Australia, Crawley, Western Australia, Australia 6009.
1This article is part of a Special Issue dedicated to Professor Arthur Carty.
2Corresponding author (e-mail: allan.canty@utas.edu.au).
Can. J. Chem. 84: 77–80 (2006)
doi:10.1139/V05-219
© 2006 NRC Canada

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Can. J. Chem. Vol. 84, 2006
Scheme 1.
R
R'
O
R
R'
O
R
R'
O
Hg
R
Hg
Hg
Hg
R'
O
R
Hg
Hg
R
Hg
OR'
Hg
R
OR'
RO'
OR'
O
R'
RO'
Hg
R
Hg
R
R
4
1
2
3
Table 1. Selected geometries for MeHgOPh.
Parameter
Parameter
Atoms
n = 1
n = 2
Atoms
n = 1
n = 2
Bond lengths (Å)
Hg(n)—C(n)
Hg(n)—O(1)
2.046(16)
2.060(11)
2.049(18)
2.719(9)
Hg(n)—O(2)
C(n1)—O(n)
2.702(9)
1.369(16)
2.063(10)
1.364(16)
Bond angles (°)
C(n)-Hg(n)-O(n)
C(n)-Hg(n)-O(n′)
O(1)-Hg(n)-O(2)
176.6(5)
109.4(5)
73.0(3)
176.3(5)
109.3(5)
72.6(3)
Hg(1)-O(n)-Hg(2)
C(11)-O(1)-Hg(n)
C(21)-O(2)-Hg(n)
106.0(4)
120.7(8)
120.6(8)
106.5(4)
123.5(8)
121.4(8)
ing much longer and at the van der Waals limit
(Hg(1)···O(1) (x, 1/2 – y, z – 1/2) 3.318(9) Å; Hg(2)···O(2)
(x, 1/2 – y, z – 1/2) 3.368(10) Å) (Fig. 1c).
reported for the trimethylsiloxo complex (4), we have syn-
thesized MeHgOPh and determined its structure in the solid
state.
Although the structure determination reveals several inter-
esting features in crystal chemistry, the structure of
MeHgOPh conforms broadly to model 1 with the additional
presence of weak intermolecular interactions, consistent
with the monomeric behaviour exhibited in dichloromethane
(6). Structural assignments for the solid state based on IR
and Raman spectroscopic data (6), are supported by the
structural determination, the spectroscopic data being insen-
sitive to the weak intermolecular Hg···O interactions.
Results and discussion
Although the complex MeHgOPh was prepared by the re-
ported method, the preparation is given in detail here in view
of the brief description reported previously (13). Crystals
were obtained from dichloromethane – light petroleum. Se-
lected geometries are given in Table 1, and views of the
structure are shown in Fig. 1.
The results of the low-temperature single crystal X-ray
structure determination are consistent with the formulation
of the complex, in terms of stoichiometry and connectivity,
as neutral MeHgOPh. Two formula units, devoid of crystal-
lographic symmetry, comprise the asymmetric unit of the
structure. These may be viewed essentially as single mole-
cules with almost linear C-Hg-O coordination (Hg—O
2.060(11) Å, 2.063(10) Å; Hg—C 2.046(16) Å, 2.049(18) Å;
C-Hg-O 176.6(5)°, 176.3(5)°). The mercury environments
lie side-by-side, quasi-inversion related (Fig. 1a), with long
Hg···O interactions (2.702(9) Å, 2.719(9) Å), appreciably
less than the van der Waals radii sum (O, 1.4 Å (14); Hg, ca.
1.73 Å (15)) that perturb the linearity of the C-Hg-O arrays.
The Hg(µ-O)2Hg arrays are quasi-planar (χ2 523) with a fold
angle across the Hg···Hg line of 17.4(6)° (Fig. 1b). The mer-
cury atoms lie out of the associated C6 ring planes by
0.17(3) Å and 0.20(2) Å, the Hg(n)-O(n)-C(n1)-C(n2) tor-
sion angles being –8(2)° and –9(2)°. C(11, 21) lie out of the
Hg2O2 “plane” by 0.22(2) Å and 0.32(2) Å. Despite these
distortions, the quasi-dimeric arrays may be considered ap-
proximately planar and, as such, stack up the c axis of the
almost orthogonal cell — Hg above O — these contacts be-
Experimental
Synthesis of MeHgOPh
Freshly precipitated silver(I) oxide (from an aqueous solu-
tion of silver(I) nitrate and sodium hydroxide) was collected
and repeatedly washed and centrifuged until the pH of the
solution was 7. An excess of Ag2O was added to MeHgCl
(6.28 g) in a small volume of water. The resulting aqueous
solution was filtered, and phenol (2.35 g) was added. The
white crystalline precipitate that formed was collected,
washed with water, and dried over phosphorus pentoxide.
The product was recrystallized from dichloromethane and
then from dichloromethane – light petroleum (bp 40–60 °C)
to give the pure complex (3.86 g, 50%). IR spectra are as re-
ported (6).
X-ray data collection, structure
determination, and refinement
Following earlier unsuccessful attempts at data acquisition
at room temperature using a four-circle instrument (the ma-
© 2006 NRC Canada

Canty et al
79
Fig. 1. (a) The asymmetric unit of the structure of MeHgOPh
projected down c and (b) oblique to the central plane; (c) Unit
cell contents projected down c. 50% Probability amplitude dis-
placement envelopes are shown for the non-hydrogen atoms, hy-
drogen atoms where shown having arbitrary radii of 0.1 Å.
Table 2. Crystal data and structure refinement for MeHgOPh.
Empirical formula
C14H16Hg2O2
Formula mass
Crystal dimensions (mm3)
Crystal system
617.5
0.30 × 0.07 × 0.06
Monoclinic
Space group
P21/c (No. 14)
Z
4
a (Å)
b (Å)
c (Å)
β (°)
10.340(2)
19.886(1)
6.914(1)
91.200(4)
–13 ≤ h ≤ 13;
Collection ranges
–11 ≤ k ≤ 11;
–8 ≤ l ≤ 8
ca. 150
1421.4(4)
2.885
Temperature (K)
Volume (Å3)
Dcalcd (Mg m–3)
Radiation
Absorption coefficient (µ) (mm–1)
F(000)
Mo Kα (λ = 0.71073 Å)
21.6
1104
θ range for data collection (°)
Measured reflections
1–27.5
27 505
Independent reflections
3 196 (Rint = 0.072)
Data/restraints/parameters
Maximum shift/error
Goodness-of-fit
2 345/(see text)/83
9×10–4
0.98
Final R indices (I > 4σ(I))
R1 = 0.064, wR2 = 0.086
R indices (all data)
Largest diff. peak and hole (e Å–3)
R1 = 0.079, wR2 = 0.096
–6.1, 5.3(2)
terial being fine whiskers), a full sphere of low-temperature
CCD area-detector diffractometer data were measured
(Bruker AXS instrument), “empirical”–multiscan absorption
correction (proprietary software) being applied (Tmin/max
=
0.28) (Table 2). The full-matrix least-squares refinement
would support meaningful anisotropic displacement parame-
ter form refinement for the mercury atoms only (x, y, z
Uiso)H, being included and constrained at estimated values
(reflection weights: (σ2(F) + 0.005F2)–1). Neutral atom com-
plex scattering factors were employed within the Xtal 3.7
program system (16).3
Acknowledgements
We thank the Australian Research Council for financial
support.
3Supplementary data for this article are available on the journal
Web site (http://canjchem.nrc.ca) or may be purchased from the
Depository of Unpublished Data, Document Delivery, CISTI, Na-
tional Research Council Canada, Ottawa, ON K1A 0R6, Canada.
DUD 4077. For more information on obtaining material refer to
http://cisti-icist.nrc-cnrc.gc.ca/irm/unpub_e.shtml. CCDC 234052
contains the crystallographic data for this manuscript. These data
can be obtained, free of charge, via www.ccdc.cam.ac.uk/conts/
retrieving.html (Or from the Cambridge Crystallographic Data
Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax
+44 1223 336033; or deposit@ccdc.cam.ac.uk).
© 2006 NRC Canada

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Can. J. Chem. Vol. 84, 2006
9. H. Schmidbaur and F. Schindler. Angew. Chem. Int. Ed. Engl.
4, 876 (1965).
References
10. A.J. Canty and B.M. Gatehouse. J. Chem. Soc. Dalton Trans.
1. J.L. Wardell. In Comprehensive organometallic chemistry.
Vol. 1. Edited by G. Wilkinson, F.G.A. Stone, and E.W. Abel.
Pergamon Press, Oxford. 1982. p. 863.
2018 (1976).
11. Y.S. Wong, P.C. Chieh, and A.J. Carty. Can. J. Chem. 51, 2597
(1973).
12. A.J. Carty, S.F. Malone, N.J. Taylor, and A.J. Canty. J. Inorg.
2. J.S. Casas, M.S. García-Tasende, and J. Sordo. Coord. Chem.
Rev. 193–195, 283 (1999).
Biochem. 18, 291 (1983).
3. L.G. Kuz′mina, N.G. Bokii, Y.T. Struchkov, D.N. Kravtsov,
and L.G. Golovchenko. Zh. Strukt. Khim. 14, 508 (1973).
4. D.C. Bradley, R.C. Mehrotra, I.P. Rothwell, and A. Singh.
Alkoxo and aryloxo derivatives of metals. Academic Press,
San Diego. 2001.
13. L.F. Sytsma and R.J. Kline. J. Organomet. Chem. 54, 15 (1973).
14. L. Pauling. The nature of the chemical bond. 3rd ed. Cornell
University Press, Ithaca, New York. 1960. p. 260.
15. A.J. Canty and G.B. Deacon. Inorg. Chim. Acta, 45, L225
(1980).
5. G. Dittmar and E. Hellner. Angew. Chem. 81, 707 (1969).
6. A.J. Canty and J.W. Devereux. Spectrochim. Acta, 36A, 495
(1980).
7. A.J. Bloodworth. J. Chem. Soc. C, 2051 (1970).
8. G. Holan. Tetrahedron Lett. 1985 (1966).
16. S.R. Hall, D.J. du Boulay, and R. Olthof-Hazekamp. The
XTAL 3.7 system [computer program]. University of Western
Australia, Crawley, Australia. 2001.
© 2006 NRC Canada