Complexation of DMF and DMSO by a monodentate organomercurial lewis acid

Article abstract of DOI:10.1021/om990081b

When crystallized from DMSO or DMF, pentafluorophenylmercury chloride (1) forms the Lewis acid-Lewis base adducts 1·DMSO (2) and (1)₂·DMF (3), respectively. These adducts have been characterized by elemental analysis, IR spectroscopy, ¹³C CP/MAS NMR (3) and X-ray single-crystal structure analysis. Compound 2 is a T-shaped complex. In the crystal, the individual molecules of 2 aggregate through formation of Hg₂Cl₂ bridges to form a ladder polymer. Compound 3 crystallizes with four independent molecules of 1 and two independent molecules of DMF in the asymmetric unit. While all molecules are part of a complex framework formed by Hg₂Cl₂ bridges, three molecules of 1 are involved in the binding of two formamide molecules, which form bridges between adjacent mercury centers.

Full text of DOI:10.1021/om990081b

2040
Organometallics 1999, 18, 2040-2042
Com p lexa tion of DMF a n d DMSO by a Mon od en ta te
Or ga n om er cu r ia l Lew is Acid
Martin Tschinkl,† Annette Schier,‡ J u¨rgen Riede,‡ and Franc¸ois P. Gabba¨ı*,†
Department of Chemistry, Texas A&M University, College Station, Texas 77843-3255, and
Anorganisch-chemisches Institut der Technischen Universita¨t Mu¨nchen, Lichtenbergstrasse 4,
D-85747 Garching, Germany
Received February 8, 1999
Summary: When crystallized from DMSO or DMF,
pentafluorophenylmercury chloride (1) forms the Lewis
acid-Lewis base adducts 1‚DMSO (2) and (1)2‚DMF (3),
respectively. These adducts have been characterized by
elemental analysis, IR spectroscopy, 13C CP/ MAS NMR
(3) and X-ray single-crystal structure analysis. Com-
pound 2 is a T-shaped complex. In the crystal, the
individual molecules of 2 aggregate through formation
of Hg2Cl2 bridges to form a ladder polymer. Compound
3 crystallizes with four independent molecules of 1 and
two independent molecules of DMF in the asymmetric
unit. While all molecules are part of a complex frame-
work formed by Hg2Cl2 bridges, three molecules of 1 are
involved in the binding of two formamide molecules,
which form bridges between adjacent mercury centers.
carbonyl carbon chemical shift in 3 (167.6 ppm vs 162.7
cm-1 in free DMF).
The results of the X-ray single-crystal analysis for 2
and 3 confirmed the nature of the complexes (Table 1).
The structure of 2 approaches that of a T-shaped
coordination complex (Figure 1) with O-Hg-Cl, O-Hg-
C(1), and C(1)-Hg-Cl angles of 93.5(1)°, 96.8(2)°, and
169.7(2)°, respectively. The Hg-O distance of 2.542(4)
Å is comparable to the distance found in the dibutyl-
sulfoxide adduct of HgCl2 (2.593(5) Å).4 Examination of
the cell-packing diagram indicates that the monomers
are associated through formation of head-to-tail Hg2Cl2
bridges (Hg′-Cl 3.131, Hg′-Cl′′ 3.450 Å) (Figure 2).
Those intramolecular distances are shorter than the
sum of the van der Waals radii of chlorine (rvdw(Cl) )
1.8 Å)5 and mercury (rvdw(Hg) ) 1.7-2.0 Å)6 and
substantiate the presence of moderate interactions. The
resulting supramolecule is a ladder polymer similar to
that found in phenylmercury chloride,7 yet in the
present case, solvated by DMSO molecules. The struc-
ture of 3 contains four independent molecules of 1 and
two independent molecules of DMF. Interestingly, three
molecules of 1 are involved in the binding of the two
DMF molecules (Figure 3). While the DMSO molecule
of 2 is terminal, the DMF molecules in 3 form bridges
between the mercury centers of three different com-
plexes and are thus doubly coordinated. The mercury
center of these three molecules is linearly coordinated
to its primary ligands, and the Hg-O bonds are ap-
proximately perpendicular to the C-Hg-Cl sequences.
The Hg-O distances in 3 (Hg(1b)-O(1b) 2.663, Hg(3b)-
O(1b) 2.776, Hg(3b)-O(2a) 2.852, Hg(2a)-O(2a) 2.666)
are very similar to those found in the structure of 1,2-
bis(chloromercurio)benzene‚µ2-DMF (2.681 and 2.777
Å), which contains a chelated DMF molecule.8,9 It must
be indicated that the fourth molecule of 1 cements the
cluster by forming Hg‚‚‚Cl intermolecular contacts with
two of its closest neighbors (Hg(4a)-Cl(2a) 3.144,
Monofunctional organomercurials such as phenyl-
mercury chloride rarely form adducts with basic sub-
strates.1 In this paper we report that pentafluoro-
phenylmercury chloride2 behaves differently than its
perprotio-analogue and complexes DMSO and DMF.
This work is part of our ongoing coordination studies of
mercury-based Lewis acids.3
Slow evaporation of the solvent from a DMSO or DMF
solution of pentafluorophenylmercury chloride (1) af-
fords in both cases a quantitative yield of large crystals
whose respective compositions are 1‚DMSO (2) and
(1)2‚DMF (3) as determined by elemental analysis. IR
spectroscopy revealed a weakening of the sulfoxide
(1019 cm-1 in 2 vs 1057 cm-1 in free DMSO) and
carbonyl (1654 cm-1 in 3 vs 1675 cm-1 in free DMF)
stretching bands, thus suggesting that in both cases
there is coordination of the terminal oxygen to the
mercury center of 1. This conclusion was corroborated
by the deshielded value of the 13C CP/MAS NMR
* Corresponding author. E-mail: gabbai@mail.chem.tamu.edu.
† Texas A&M University.
‡ Anorganisch-chemisches Institut der Technischen Universita¨t
Mu¨nchen.
(1) Organomercurials sometimes form adducts with polydendate
Lewis bases. See for example: (a) Onan, K.; Rebek J unior, J .; Costello,
T.; Marshall L. J . Am. Chem. Soc. 1983, 105, 6759. (b) Ruiz-Amil, A.;
Martinez-Carrera, S.; Garcia-Blanco, S. Acta Crystallogr. Sect. B 1978,
34, 2711. (c) Redhouse, A. D. J . Chem. Soc., Chem. Commun. 1972,
1119. (d) Canty, A. J .; Gatehouse, B. M. Acta Crystallogr. Sect. B 1972,
28, 1872.
(4) Biscarini, P.; Fusina, L.; Nivellini, G. D.; Pelizzi, G. J . Chem.
Soc., Dalton Trans. 1981, 1024-1027.
(5) Nyburg, S. C.; Faerman, C. H. Acta Crystallogr. Sect. B 1985,
41, 274-279.
(6) Canty, A. J .; Deacon, G. B. Inorg. Chim. Acta 1980, 45, L225-
L227.
(7) Pakhomov, V. I. Zh. Strukt. Kim. 1963, 4, 594-601.
(8) Beauchamp, A. L.; Olivier, M. J .; Wuest, J . D.; Zacharie, B.
Organometallics 1987, 6, 153-156.
(2) Chambers, R. D.; Coates, G. E.; Livingstone, J . G.; Musgrave,
W. K. R. J . Chem. Soc. 1962, 4367-4371.
(3) See for example: (a) Tschinkl, M.; Schier, A.; Riede, J .; Gabba¨ı,
F. P. Organometallics, in press. (b) Tschinkl, M.; Schier, A.; Riede, J .;
Mehltretter, G.; Gabba¨ı, F. P. Organometallics 1998, 17, 2921-2923.
(c) Tschinkl, M.; Schier, A.; Riede, J . Gabba¨ı, F. P. Inorg. Chem. 1997,
36, 5706-5711.
(9) Bridging DMF molecules have been observed in the solid state
of inorganic alkali salts. See for example: (a) Markley, T. J .; Toby B.
H.; Pearlstein, R. M.; Ramprasad, D. Inorg. Chem. 1997, 36, 3376-
3378. (b) Ramprasad, D.; Pez, G. P.; Toby, B. H.; Markley, T. J .;
Pearlstein, R. M. J . Am. Chem. Soc. 1995, 117, 10694-10701.
10.1021/om990081b CCC: $18.00 © 1999 American Chemical Society
Publication on Web 04/25/1999

Notes
Organometallics, Vol. 18, No. 10, 1999 2041
Ta ble 1. Cr ysta l Da ta , Da ta Collection , a n d Str u ctu r e Refin em en t for 2 a n d 3
2
3
Crystal Data
C8H6ClF5HgOS
481.23
formula
Mr
C7.5H3.5ClF5HgN0.5O0.5
439.65
cryst syst
space group
a (Å)
b (Å)
c (Å)
monoclinic
P21/n
13.693(1)
6.292(1)
14.120(1)
90
105.41(1)
90
1172.8(2)
2.725
triclinic
P1h
10.445(1)
12.962(3)
15.404(3)
101.37(1)
95.97(1)
92.78(1)
2028.4(6)
2.879
R (deg)
â (deg)
γ (deg)
V (Å3)
F
calc (g cm-3
Z
)
4
8
F(000) (e)
880
135.7
1584
154.8
µ(Mo KR)(cm-1
)
Data Collection
T (°C)
scan mode
hkl range
-70
-97
0f16, -7f7, -17f16
4555
-12f12, -15f15, 0f18
7891
no. of measured reflns
no. of unique reflns, [Rint
no. of reflns used for refinement
abs corr
]
2297, [Rint ) 0.0214]
7891, [Rint ) 0.000]
2222
7154
DIFABS
DIFABS
Refinement
154
no. of refined params
final R values [I > 2σ(I)]
R1a (%)
559
0.0318
0.0833
1.496/-2.926, at Hg atom
0.0356
0.0874
wR2b (%)
Ffin (max/min) (e Å-3
)
1.375/-2.364, at Hg atoms
R1 ) ∑(Fo - Fc)/∑Fo. wR2 ) {[∑w(Fo - Fc2)2]/∑[w(Fo2)2]}1/2; w ) 1/[σ2(Fo2) + (ap)2 + bp]; p ) (Fo + 2Fc2)/3; a ) 0.0692 (2), 0.0642
a
b
2
2
(3); b ) 0.5606 (2), 4.4107 (3).
F igu r e 1. ORTEP drawing of 2 with 50% probability
ellipsoids; H atoms omitted for clarity. Selected bond
F igu r e 2. Stick and ball diagram showing the formation
of ladders solvated by DMSO molecules in the structure of
2. The DMSO molecules are represented by thin lines for
clarity.
lengths (Å) and angles (deg): Hg-C(1) 2.081(6), Hg-Cl
2.322(2), Hg-O 2.542(4), S-O 1.516(4); C(1)-Hg-Cl
169.7(2), O-Hg-C(1) 96.8(2), O-Hg-Cl, 93.5(1), S-O-
Hg 119.3(2).
The present results show that when electron-with-
drawing substituents are present, monodentate organo-
mercurials can form adducts with neutral bases such
as formamides and sulfoxides. We also demonstrate
that, at least in the solid state, the double coordination
Hg(4a)-Cl(3b) 3.101, Hg(2a)-Cl(4a) 3.136, Hg(3b)-
Cl(4a) 3.455 Å). In addition, the three juxtaposed
perfluorinated phenyl groups are close enough to be
involved in π-π interactions (C(34b)-C(14b) 3.479 Å
of a carbonyl function can be achieved by two inde-
and C(34b)-C(24a) 3.370 Å). In the crystal, the tetra-
pendent monodentate organomercurials and does not
nuclear clusters aggregate through formation of ad-
ditional Hg‚‚‚Cl intermolecular interactions to form a
complex ribbon (Figure 4) whose structure differs mark-
edly from the simple ladder observed in the structure
of phenylmercury chloride.
necessitate the use of a bifunctional Lewis acid.10
A
study of the behavior of 1 in solution is presently under
way.
(10) Wuest, J . D. Acc. Chem. Res. 1998, 32, 81-89.

2042 Organometallics, Vol. 18, No. 10, 1999
Notes
measurements were carried out at 25 °C. The Laboratory for
Microanalysis at Technische Universita¨t Mu¨nchen performed
the elemental analyses. The infrared spectra were recorded
in KBr pellets. All melting points were measured on samples
in sealed capillaries and are uncorrected. DMSO and DMF
were distilled prior to use and stored over molecular sieves.
All commercially available starting materials were purchased
from Aldrich Chemicals and used as provided. Compound 1
was prepared according to the published procedure.2
P en ta flu or op h en ylm er cu r y Ch lor id e‚DMSO (2). A 50
mg sample of 1 was placed in a vial and dissolved in 0.5 mL
of DMSO. The solvent was then allowed to evaporate in a well-
aerated fume hood over a period of 3 weeks. A quantitative
amount of crystalline 2 could then be collected. mp 54 °C. Anal.
Calcd for C8H6ClF5HgOS: C, 19.95; H, 1.25. Found: C, 20.22;
H, 1.37. IR: 3427, 1642, 1509, 1474, 1374, 1315, 1081, 1069,
1019, 965, 807 cm-1
.
(P en ta flu or op h en ylm er cu r y ch lor id e)4‚(DMF )2 (3). A
50 mg sample of 1 was placed in a vial with a small aperture
and dissolved in 0.5 mL of DMF. The solvent was then allowed
to evaporate in a well-aerated fume hood. After a week
colorless crystals of 3 could be isolated in a quantitative yield,
mp 98 °C. Anal. Calcd for C15H7Cl2F10Hg2NO: C, 20.47; H,
0.79; N, 1.52. Found: C, 20.32; H, 0.79; N, 1.45. 13C CP/MAS
NMR (7.05 T) for 3: δ 31.0, 35.7 (CH3), 120-155 (br, C-aryl),
168.2 (CO). IR: 3427, 1654, 1642, 1522, 1474, 1384, 1374,
F igu r e 3. Stick and ball diagram of 3. H and F atoms
omitted for clarity. Selected intramolecular bond lengths
(Å) and angles (deg): Hg(1b)-C(11b) 2.054(9), Hg(2a)-
C(21a) 2.059(9), Hg(3b)-C(31b) 2.086(8), Hg(4a)-C(41a)
2.063(8), Hg(1b)-Cl(1b) 2.312(2), Hg(2a)-Cl(2a) 2.301(3),
Hg(3b)-Cl(3b) 2.316(2), Hg(4a)-Cl(4a) 2.338(2); C(11b)-
Hg(1b)-Cl(1b) 177.1(3), C(21a)-Hg(2a)-Cl(2a) 173.4(3),
C(31b)-Hg(3b)-Cl(3b) 178.0(2), C(41a)-Hg(4a)-Cl(4a)
177.3(2). Selected intermolecular bond lengths (Å) and
angles (deg): Hg(1b)-O(1b) 2.663, Hg(3b)-O(1b) 2.776,
Hg(3b)-O(2a) 2.852, Hg(2a)-O(2a) 2.666, Hg(1b)-O(1b)
2.663, Hg(3b)-O(1b) 2.776, Hg(3b)-O(2a) 2.852, Hg(2a)-
O(2a) 2.666; Cl(2a)-Hg(2a)-O(2a) 89.3, C(21a)-Hg(2a)-
O(2a) 95.2, Cl(3b)-Hg(3b)-O(1b) 84.4, C(31b)-Hg(3b)-
O(1b) 97.7, Cl(3b)-Hg(3b)-O(2a) 84.5, C(31b)-Hg(3b)-
O(2a) 94.6, Cl(1b)-Hg(1b)-O(1b) 88.6, C(11b)-Hg(1b)-
O(1b) 93.6.
1328, 1097, 1011, 965, 807 cm-1
.
Cr ysta l Str u ctu r e Deter m in a tion of 2 a n d 3. Single
crystals of suitable quality and size were mounted in glass
capillaries and used for measurements of precise cell constants
and intensity data collection on an Enraf Nonius CAD4
diffractometer (Mo KR radiation, λ(Mo KR) ) 0.710 73 Å).
During data collection, three standard reflections were meas-
ured periodically as a general check of crystal and instrument
stability. No significant changes were observed for all com-
pounds. Lp correction was applied, and intensity data were
corrected for absorption effects. The structures were solved by
direct methods and refined by full-matrix least-squares tech-
niques against F2 (SHELXL-93). The thermal motion of all
non-hydrogen atoms was treated anisotropically. All hydrogen
atoms were placed in idealized calculated positions and
allowed to ride on their corresponding carbon atoms with fixed
isotropic contributions (Uiso(fix) ) 1.5Ueq of the attached C atom).
Further information on crystal data, data collection, and
structure refinement are summarized in Table 1. Important
bond lengths and angles have been gathered in the figure
captions of Figures 1-3.
Ack n ow led gm en t. We thank the Department of
Chemistry at Texas A&M University and Prof. H.
Schmidbaur for making this work possible. We are
grateful to Robert Taylor (Texas A&M University) for
the recording of the solid-state NMR spectra. Financial
support from the State of Bavaria/Technische Univer-
sita¨t Mu¨nchen and the DAAD (Promotionsstipendium,
grant to M.T.) is thankfully acknowledged.
F igu r e 4. Stick and ball diagram showing a portion of the
polymeric aggregate formed in the supramolecular struc-
ture of 3. All H, C, F, and N have been omitted (with the
exception of the Cipso atoms).
Exp er im en ta l Section
Gen er a l P r oced u r es. The solid-state 13C CP/MAS NMR
spectra were recorded on a Bruker MSL 300 spectrometer
operating at a field strength of 7.05 T. Cross-polarization and
high-power proton decoupling were applied with a 90° pulse
time of 5 ms, a contact time of 5 ms, and a recycle delay of 8
s. 13C NMR shifts are referenced to an external sample of
adamantane, with the signal at low frequency being set to
29.472 ppm relative to TMS. Approximately 50 mg of the
sample was packed into 4 mm ZrO2 Bruker rotors with Kel-F
caps. The rotor spinning speed was 7 kHz for 3. All NMR
Su p p or tin g In for m a tion Ava ila ble: Tables of atomic
coordinates and isotropic thermal parameters, complete bond
lengths and angles, anisotropic thermal parameters, hydrogen
atom coordinates, and thermal parameters for 2 and 3. This
material is available free of charge via the Internet at
http://pubs.acs.org.
OM990081B