The synthesis and characterization of compounds of the type Hg{1-C6H4-2-C(H)= NC6H5-nRn}2

Article abstract of DOI:10.1021/ic010881q

The organomercurial compounds Hg{1- C₆H₄-2-C(H)= NC₆H_5-nR_n}₂ (R = 4-NMe₂, 6a; 4-Me, 6b; 4-I, 6c; 4-NO₂, 6d; 2-ⁱPr, 6e; 2-Me, 6f; 2,6-ⁱ Pr₂, 6g; 2,6-Me₂, 6h) have been prepared in good overall yield from 2-bromobenzaldehyde. All of the compounds have been characterized by elemental analysis, ¹H NMR, ¹³C{¹H} NMR, and infrared spectroscopy. In addition, compounds 6a [C₃₀H₃₀HgN₄, triclinic, P1, a = 6.20000(10) A, b = 9.2315(2) A, c = 10.9069(3) A, α = 85.8510(10)°, β = 89.3570(10)°, γ = 87.206(2)°, Z = 1], 6b [C₂₈H₂₄HgN₂, monoclinic, P2₁/c, a = 12.8260(5) A, b = 14.0675(4) A, c = 6.1032(2) A, β = 90.0990(10)° Z = 2], 6g [C₃₈H₄₄HgN₂, triclinic, P1, a = 8.2626(2) A, b = 9.8317(2) A, c= 11.8873(3) A, α = 103.6650(10)°, β = 109.3350(10)°, γ = 104.627(2)°, Z = 1], and 6h [C₃₀H₂₈HgN₂, monoclinic, P2₁/c, a = 12.5307(2) A, b = 10.9852(2) A, c = 18.2112(2) A, β = 104.0190(10)°, γ = 87.206(2)°, Z = 4] have been characterized by low-temperature single-crystal X-ray diffraction studies, and two different molecular geometries about the central mercury atom have been observed; intramolecular contacts suggest a van der Waals radius for Hg of 2.1-2.2 A.

Full text of DOI:10.1021/ic010881q

Inorg. Chem. 2002, 41, 1907−1912
The Synthesis and Characterization of Compounds of the Type
Hg{1-C H -2-C(H)dNC H R }
6 4
6 5-n n 2
Kevin R. Flower,* Victoria J. Howard, Shakil Naguthney, Robin G. Pritchard, and John E. Warren
Department of Chemistry, UMIST, PO Box 88, Manchester, U.K., M60 1QD
Alan T. McGown
CRC Drug DeVelopment Group, Paterson Institute for Cancer Research, Christie Hospital,
Manchester, U.K., M20 4BX
Received August 20, 2001
The organomercurial compounds Hg{1-C H -2-C(H)dNC H5-nR }2 (R ) 4-NMe2, 6a; 4-Me, 6b; 4-I, 6c; 4-NO ,
6
4
6
n
2
i
i
6d; 2-Pr, 6e; 2-Me, 6f; 2,6-Pr2, 6g; 2,6-Me , 6h) have been prepared in good overall yield from 2-bromobenzaldehyde.
2
All of the compounds have been characterized by elemental analysis, H NMR, 13C{1H} NMR, and infrared
1
spectroscopy. In addition, compounds 6a [C H HgN , triclinic, P1h, a ) 6.20000(10) Å, b ) 9.2315(2) Å, c )
30 30
4
10.9069(3) Å, R ) 85.8510(10)°, â ) 89.3570(10)°, γ ) 87.206(2)°, Z ) 1], 6b [C H HgN , monoclinic, P21/c,
28 24
2
a ) 12.8260(5) Å, b ) 14.0675(4) Å, c ) 6.1032(2) Å, â ) 90.0990(10)°, Z ) 2], 6g [C H HgN , triclinic, P1h,
38 44
2
a ) 8.2626(2) Å, b ) 9.8317(2) Å, c ) 11.8873(3) Å, R ) 103.6650(10)°, â ) 109.3350(10)°, γ ) 104.627(2)°,
Z ) 1], and 6h [C H HgN , monoclinic, P21/c, a ) 12.5307(2) Å, b ) 10.9852(2) Å, c ) 18.2112(2) Å, â )
30 28
2
104.0190(10)°, γ ) 87.206(2)°, Z ) 4] have been characterized by low-temperature single-crystal X-ray diffraction
studies, and two different molecular geometries about the central mercury atom have been observed; intramolecular
contacts suggest a van der Waals radius for Hg of 2.1−2.2 Å.
Introduction
developed by Roper et al.,6 of some cycloruthenated com-
plexes of the type [RuX(CE)(η2-C,N-C6H4NdNC6H5)-
(PPh3)2] (X ) Cl, Br, I; E ) O, S) which showed an
interesting cis-push-pull effect that was moderated by the
cycloruthenated azobenzene ligand, and we showed that it
is similar in nature to the tautomeric process undergone by
orthohydroxyazobenzes.7 Since it is known that 2-phenyl-
iminophenols are known to undergo the same tautomeric
process,8 we were keen to prepare some analogous com-
pounds. Perusal of the literature suggested that there were
no examples of the symmetric diorganomercurials Hg{1-
C6H4-2-C(H)dNC6H5-nRn}2 which would be required to
The first reported study of an organomercurial compound
was described by Frankland in 1852,1 with the first diorga-
nomercurial synthesized in 1858 obtained by symmetrization
of MeHgI using KCN!2 Since then a wide range of methods
have been developed for forming a mercury-carbon bond,
and they include transmetalation using electropositive alkali
metal or main group organometallic reagents, mercury-
hydrogen exchange, solvomercuriation, decarboxylation,
desulfination, reaction with diazonium salts, carbene insertion
into a mercury halogen bond and symmetrization. All of these
methodologies have been comprehensively reviewed,3 as
have the solid state structures of this class of compound.4
We recently reported5 the synthesis, using the methodology
(4) (a) Casas, J. S.; Garcia-Tasende, M. S.; Sardo, J. Coord. Chem. ReV.
1999, 195, 283. (b) Holloway, C. E.; Meln´ık, M. J. Organomet. Chem.
1995, 495, 1.
* Author to whom correspondence should be addressed. E-mail:
k.r.flower@umist.ac.uk.
(5) (a) Cross, W. I.; Flower, K. R.; Pritchard, R. G. J. Organomet. Chem.
2000, 601, 164. (b) Flower, K. R.; Pritchard, R. G. J. Organomet.
Chem. 2001, 620, 60.
(6) Roper, W. R.; Wright, L. J. J. Organomet. Chem. 1977, 142, C1.
(7) (a) Venkataraman, K. Synthetic Dyes; Academic Press: New York,
1952; Vol. 1. (b) Zollinger, H. Azo and Diazo Chemistry; Wiley-
Interscience: New York, 1961.
(1) Frankland, E. Philos. Trans. R. Soc. London 1852, 142, 417.
(2) Buckton, G. B. Philos. Trans. R. Soc. London 1858, 148, 163.
(3) (a) Wardell, J. L. In ComprehensiVe Organometallic Chemistry;
Wilkinson, G., Stone, F. G. A., Abel, E. W., Eds.; Pergamon: Oxford,
1982; Vol. 1, p 865. (b) Davies, A. G.; Wardell, J. L.In ComprehensiVe
Organometallic Chemistry II; Wilkinson, G., Stone, F. G. A., Abel,
E. W., Eds.; Pergamon: Oxford, 1995; Vol. 1.
(8) Antonov, L.; Fabian, W. M. F.; Nedeltcheva, D.; Kamounah, F. S. J.
Chem. Soc., Perkin Trans. 2 2000, 1173.
10.1021/ic010881q CCC: $22.00 © 2002 American Chemical Society
Published on Web 03/14/2002
Inorganic Chemistry, Vol. 41, No. 7, 2002 1907

Flower et al.
Table 1. Physical, Analytical,a and Infrared Datab for 2, 4, 5, and 6a-h
anal. data
H
compd
color
yield (%)
95
C
N
IR (cm-1
)
2 1-BrC6H4-2-CHOCH2OCH2
colorless
liquid
white
47.4
(47.2)
43.5
(43.3)
41.1
(40.9)
55.9
(55.7)
57.1
(57.1)
38.3
(38.4)
48.1
(48.0)
59.5
(59.6)
56.9
(57.1)
62.5
(62.6)
58.5
(58.4)
3.9
(4.0)
3.6
(3.6)
2.5
(2.5)
4.7
(4.7)
4.1
(4.1)
1.9
(2.2)
2.6
(2.8)
5.2
(5.0)
4.0
(4.1)
6.1
(6.1)
4.7
(4.6)
4 Hg(1-C6H4-2-CHOCH2OCH2)
74
88
69
76
73
75
81
67
84
82
5 Hg(C6H4-2-CHO)
white
1680, ν(CO)
1618, ν(CN)
1624, ν(CN)
1620, ν(CN)
1624, ν(CN)
6a Hg{1-C6H4-2-C(H)dNC6H4-4-NMe2}
6b Hg{1-C6H4-2-C(H)dNC6H4-4-Me}
6c Hg{1-C6H4-2-C(H)dNC6H4-4-I}
6d Hg{1-C6H4-2-C(H)dNC6H4-4-NO2}
6e Hg{1-C6H4-2-C(H)dNC6H4-2-iPr}
6f Hg{1-C6H4-2-C(H)dNC6H4-2-Me}
6g Hg{1-C6H4-2-C(H)dNC6H3-2,6-iPr2}
6h Hg{1-C6H4-2-C(H)dNC6H3-2,6-Me2}
yellow
white
8.5
(8.7)
4.6
(4.8)
3.2
(3.4)
8.5
(8.6)
4.3
(4.3)
4.7
(4.8)
3.8
(3.8)
4.6
off-white
yellow
white
1585, 1335 (NO2)
1618, ν(CN)
white
1628, ν(CN)
1637, ν(CN)
1633, ν(CN)
white
white
(4.6)
a Calculated values in parentheses. b Spectra recorded as Nujol mulls between KBr plates; all bands strong.
a
Scheme 1
and angles (deg). It should be noted here that during the
course of this work an alternative route to 5 has been
described.9
The 1H NMR spectra are all consistent with the formula-
tion of compounds 2, 4, 5, and 6a-h; in particular,
incorporation of mercury was readily confirmed by the
observation of 199Hg satellites (Table 2). Assignment of the
13C{1H} NMR data was carried out with the aid of Dept
135 spectra, the presence of 199Hg satellites, and published
substituent effects;10 see Figure 1 for numbering scheme.
Compounds 6a, 6b, 6g, and 6h have also been character-
ized by a low-temperature single-crystal X-ray diffraction
study; except for 6g, where there was disorder in one of the
iPr groups, the hydrogen atoms were located in the difference
map; see Figures 2-5 for ORTEP11 representations showing
the atomic numbering schemes (because of the disorder in
the iPr group C(14)-C(16) in compound 6g, for clarity only
one orientation is shown in Figure 4) and Table 4 for selected
bond lengths (Å) and angles (deg). Further, compounds 6a,
6b, and 6g all display a center of inversion, whereas 6h does
not. In all cases the Hg(II) coordination geometry is linear.
The distance between the imine nitrogen and mercury center
(approximately 2.8 Å) is slightly less than the sum of the
van der Waals radii (3.05 Å),12 see later discussion, and
substantially longer than the sum of the covalent radii (2.18
Å),12 so at best there is a weak interaction.
a
(i) HOCH2CH2OH, PhCH3, 4-MeC6H4SO3H, 24 h; (ii) Mg, THF, 3 h;
(iii) HgBr2, 18 h; (iv) 4-MeC6H4SO3H, CH3C(O)CH3 12 h; (v) RnC6H5-nNH2,
EtOH, 3 h.
prepare these compounds, so we set about determining a
strategy to synthesize them.
In all of the structures the imine phenyl group rotates out
of the plane to minimize steric interactions with the hydrogen
Results and Discussion
Starting from 2-bromobenzaldehyde the orthomercuriated
phenylimines 6a-h were prepared in good overall yield as
illustrated in Scheme 1. The new compounds have all been
characterized by elemental analysis and infrared spectroscopy
(9) Rickard, C. E. F.; Roper, W. R.; Tutone, F.; Woodgate, S. D.; Wright,
L. J. J. Organomet. Chem. 2001, 619, 293.
(10) (a) Kalinowski, H. O.; Berger, S.; Braun, S. Carbon-13 NMR
Spectroscopy; Wiley-Interscience: New York, 1988. (b) Tupciauskas,
A. P.; Sergeyev, N. M.; Ustynyuk, A. N.; Kashin, A. N. J. Magn.
Reson. 1972, 7, 124.
1
(Table 1) and H NMR and 13C{1H} NMR spectroscopy
(11) Johnson, C. K. ORTEP II; Report ORNL-5138; Oak Ridge National
Laboratory: Oak Ridge, TN, 1976.
(12) Book of Data Chemistry and Physics; Nuffield Advanced Science-
Longman: London, 1972.
(Tables 2 and 3); additionally compounds 6a, 6b, 6g, and
6h have been further characterized by single-crystal X-ray
diffraction studies; see Table 4 for selected bond lengths (Å)
1908 Inorganic Chemistry, Vol. 41, No. 7, 2002

Compounds of the Type Hg{1-C6H4-2-C(H)dNC6H5-nRn}2
Table 2. 1H NMR Data for Compoundsa 2, 4, 5, and 6a-h
compd
δ
2
4
5
7.6-7.3 (m, 4H, aryl-H); 6.13 (s, 1H, CH); 4.3-3.9 (m, 4H, CH2)
7.6-7.3 (m, 4H, aryl-H); 5.87 (s, JHHg 9.4, 1H CH); 4.3-3.9 (m, 4H, CH2)
10.24 (s, JHHg 10.4, 1H, CHO); 7.9-7.4 (m, 4H, aryl-H)
6a
6b
6c
6db
6e
6f
6g
6h
8.76 (s, JHHg 11.8, 1H CH); 7.7-7.3 (m, 4H, aryl-H); 7.09 (d, JHH 9.0, 2H, aryl-H); 6.6 (d, JHH 9.0, 2H, aryl-H); 2.91 (s, 6H, NCH3)
8.73 (s, JHHg 11.8, 1H CH); 7.7-7.3 (m, 4H, aryl-H); 7.03 (m, 4H, aryl-H); 2.31 (s, 3H, CH3)
8.65 (s, JHHg 11.8, 1H CH); 7.7-7.3 (m, 4H, aryl-H); 7.53 (d, JHH 8.8, 2H, aryl-H); 6.75 (d, JHH 8.8, 2H, aryl-H)
8.68 (s 1H, CH); 8.14 (d, JHH 9.0, 2H, aryl-H); 7.7-7.4 (m, 4H, aryl-H); 7.08 (d, JHH 9.0, 2H, aryl-H)
8.51 (s 1H, JHHg 9.8, CH); 7.6-7.1 (m, 7H, aryl-H); 6.68 (m, 1H, aryl-H); 3.47 (sep, JHH 7.2, 1H, CH); 0.85 (d, JHH 7.2, 6H, CH3)
8.50 (s 1H, JHHg 10.4, CH); 7.6-7.0 (m, 7H, aryl-H); 6.73 (m, 1H, aryl-H); 2.15 (s, 3H, CH3)
8.44 (s 1H, JHHg 11.9, CH); 7.6-7.0 (m, 7H, aryl-H); 3.07 (sep, JHH 6.8, 2H, CH); 1.14 (d, JHH 6.8, 12H, CH3)
8.42 (s 1H, JHHg 11.6, CH); 7.6-7.3 (m, 4H, aryl-H); 7.0-6.9 (m, 3H, aryl-H); 2.09 (s, 6H, CH3)
a Spectra recorded in CDCl3 at 298 K; coupling constants in hertz. b Sample poorly soluble.
Table 3. 13C{1H} NMR Data for Compoundsa,b 2, 4, 5, 6a-c, and 6e-h
C(9)
C(10)
other
compd
C(1)
C(2)
C(3)
C(4)
C(5)
C(6)
C(7)
C(8)
C(9′)
C(10′)
C(11)
resonances
2
122.8
132.8
130.4
127.3
127.7
136.5
CH, 102.4
CH2, 65.3
4
167.3
J 1316
168.5
J 1251
167.1
138.0
J 82
139.2
J 80
139.3
J 114
139.3
J 100
139.3
139.1
J 88
139.2
J 98
138.1
J 89
139.0
J 90
129.4
J 110
134.4
112
127.4
128.1
126.9
127.1
128.9
J 84
135.2
87
132.3
J 82
133.0
J 84
133.5
133.4
J 82
133.4
J 83
133.1
J 85
133.0
J 87
143.9
J 36
144.0
J 44
144.6
19
144.0
J 22
143.5
143.5
J 20
143.5
J 28
142.7
J 19
142.9
J 23
CH, 105.4, J 56
CH2, 65.0
CO, 195.6, J 48.
5
6a
6b
130.5
J 121
131.2
J 122
131.8
131.3
J 119
131.3
J 119
131.6
J 117
131.6
J 117
159.2
J 56
162.9
J 48
164.2
164.6
J 50
164.6
J 46
166.6
J 48
167.2
J 51
139.9
148.2
122.9
120.9
112.81
129.6
149.3
135.7
NCH3, 41.2
CH3, 21.0
167.4
J 1488
167.4
167.3
J 1449
167.4
J 1460
166.9
J 1487
166.8
J 1468
6cc
6e
127.4
127.3
150.2
149.9
123.0
142.4
118.7
131.9
118.4
139.1
138.1
126.3
125.0
130.0
125.4
123.0
90.4
125.7
CH, 27.7
CH3, 23.2
CH3, 18.3
6f
127.3
127.5
127.3
151.2
149.5
151.2
126.6
124.1
123.6
6g
6h
CH, 28.1
CH3, 23.6
CH3, 18.6
127.7
127.9
a All spectra recorded in CDCl3 at 298 K. b All coupling constants are JCHg in hertz. c Poorly soluble, unable to observe coupling constants.
Figure 1. Numbering scheme for 13C{1H} NMR data.
Figure 3. ORTEP representation of 6b showing the atomic numbering
scheme, ellipsoids at 50%.
Figure 2. ORTEP representation of 6a showing the atomic numbering
scheme, ellipsoids at 50%.
Figure 4. ORTEP representation of 6g showing the atomic numbering
scheme, ellipsoids at 50%.
bound to C(2). The torsion angles (Table 4) for 6a and 6b
(46°, 41°) are significantly less than for 6g and 6h (-110°,
contact within the sum of the van der Waals radii was carried
out.14 This search afforded 72 hits, of which five contained
-63°), and this must be a result of the steric bulk of the
i
hydrogen versus methyl versus Pr (largest torsion angle)
groups. A search of the CCDC13 using a very general
template that considered any compound with at least one
Hg-C bond and either an inter- or intramolecular Hg-N
(13) Allen, F. H.; Davies, J. E.; Johnson, O. J.; Kennard, O.; Macrae, C.
F.; Mitchell, E. M.; Mitchell, G. F.; Smith, J. M.; Watson, J. J. Chem.
Inf. Comput. Sci. 1991, 31, 187.
Inorganic Chemistry, Vol. 41, No. 7, 2002 1909

Flower et al.
Figure 5. ORTEP representation of 6h showing the atomic numbering
scheme, ellipsoids at 50%.
Chart 1
an orthomercuriated phenylimine.15 The closest structural
analogue of the compounds 6a, 6b, 6g, and 6h is I, Chart 1,
and has a ferrocene backbone.15a Interestingly, the geometry
of compound I, about the mercury atom, most closely
resembles that observed for 6a, 6b, and 6g. The other four
compounds are of type II.15b-e For I the Hg-N contacts are
3.040(6) and 2.981(6) Å, respectively, with C-Hg-C )
174.7(3)° and N-Hg-N 157.1(2)°, respectively, and for the
compounds of type II, which contain only one Hg-N
contact, the average Hg-N distance is 2.85 Å (range: 2.76-
2.87 Å) and is comparable to the Hg-N distances in 6a,
6b, and 6g and noticeably longer than in 6h. One question
that arises is, why does 6h have a different coordination
geometry about the mercury atom?
There is currently16 a lot of interest in weak secondary
interactions and their affect on solid state structures. To
investigate whether there were any secondary interactions
in any of the diorganomercurials 6a, 6b, 6g and 6h, a full
Platon17 analysis was carried out. When the normally quoted
value of 1.55 Å is used for the van der Waals radius,14 it is
apparent that there are no close interactions. There is,
however, some controversy4a concerning the van der Waals
radius of mercury, with Canty and Deacon suggesting18
a
value of 1.73 Å, which is comparable to that recently
(14) Bondi, A. J. Phys. Chem. 1964, 68, 441.
(15) (a) Liu, Y. H.; Wu, J. W.; Huo, S. Q.; Yuan, H. Z. J. Organomet.
Chem. 1997, 534, 7. (b) Wu, Y. J.; Cui, L. C.; Liu, Y. H. J. Organomet.
Chem. 1997, 543, 63. (c) Huo, S. Q.; Wu, Y. J. J. Organomet. Chem.
1995, 490, 243. (d) Wu, Y. J.; Huo, S. Q.; Zhu, Y.; Yang, L. J.
Organomet. Chem. 1994, 481, 235. (e) Huo, S. Q.; Wu, Y. J.; Zhu,
Y.; Yang, L. J. Organomet. Chem. 1994, 470, 17.
(16) Desirajau, G. R.; Steiner, T. The Weak Hydrogen Bond; Oxford
University Press Inc.: New York, 1999.
(17) Spek, A. L. Acta Crystallogr., Sect. A 1990, 46, C-34.
(18) Canty, A. J.; Deacon, G. B. Inorg. Chim. Acta 1980, 45, L225.
1910 Inorganic Chemistry, Vol. 41, No. 7, 2002

Compounds of the Type Hg{1-C6H4-2-C(H)dNC6H5-nRn}2
calculated by Pyykko and Straka [1.75(7) Å],19 but it is
accepted that a value up to 2.0 Å may be possible. Further,
Batsanov even proposed20 values between 2.1 and 2.2 Å.
Conclusion
We have synthesized a series of bis-orthomercuriated (2-
phenylimino)phenyls starting from 2-bromobenzaldehyde in
good overall yield. Four of the compounds have been
structurally characterized, three of which have coplanar
mercuriated aryl groups and one where the mercuriated aryl
rings are perpendicular. On the basis of close Hg‚‚‚H contacts
we concur with others that the van der Waals radius for
mercury of 1.55 Å is too short and that the suggestion of
Batsanov of between 2.1 and 2.2 Å is not unreasonable.
The closest hydrogen distance to mercury is Hg‚‚‚
H(34c)C(34) 3.184(2) Å, Hg-H-C 131.3(5)°, which could
only be considered a contact if the van der Waals radius of
Hg was 2.0 Å, and even then it would be weak; further, this
would be an agostic interaction,21 not a hydrogen bond.22
Calculations that have been carried out on [Hg(CFdCF2)2]23
and [Hg(CHdCH2)2]24 show that there is free rotation about
the Hg-C bond and that there are minima when the groups
are coplanar and perpendicular, with the perpendicular
orientation being the lowest energy conformation. For the
compound Hg(CFdCF2)2 the theoretical geometry optimiza-
tion (MP2/DZP level) showed that there was also a shallow
potential-energy minimum when the perfluorovinyl groups
were nearly perpendicular [Φ(CdC‚‚‚CdC) ) 98.2°];23
remarkably the dihedral angle in the solid state structure of
6h [Φ(C(6)dC(1)‚‚‚C(21)dC(22)) ) 99.7°] is similar.
However the solid state structure of Hg(CFdCF2)2 had
coplanar vinyl groups with three intermolecular Hg‚‚‚F
contacts: 2.964(5), 3.503(5), 3.129(5) Å in the solid state
leading to essentially octahedral coordination about the
mercury atom. For the Hg‚‚‚F contact of 3.503(5) Å to be
considered within the sum of the van der Waals radii, the
van der Waals radius of mercury needs to be at least 2.0 Å,
a value that is similar to that required for Hg‚‚‚H(34c)C(34)
and considered by others to be reasonable.4a,18 Considering
the solid state structure of 6g, where there is some disorder
in one of the isopropyl groups, in the ordered group the Hg‚
‚‚H(17) distance is 3.348(3) Å with the Hg-H-C angle155.4-
(6)°. This almost linear orientation of Hg-H-C is not
consistent with an agostic interaction,21,22 so it should be
assumed to be outside or on the limit of the sum of the van
der Waals radii, hence a possible reason for the disorder seen
in the other iPr group. If this is the case, the changing nature
of the agostic interaction in 6h and 6g makes the suggestion20
of Batsanov of 2.1-2.2 Å for the van der Waals radius of
mercury not unreasonable. It may also help to explain why
the perpendicular orientation of the aryl rings in 6h is
observed: the Hg‚‚‚H distance would be within the sum of
the van der Waals radii and hence strong enough to aid in
stabilizing this orientation. Similarly the Hg‚‚‚F distance
3.503(5) Å in Hg(CFdCF2)2 would be within the sum of
the van der Waals radii. Finally, these data would suggest
that the secondary Hg‚‚‚N interaction is noticeably stronger
than previously thought.15
Experimental Section
General. All chemicals were purchased from commercial
sources, and solvents were dried by refluxing under N2 over an
appropriate drying agent and distilled prior to use, THF (K), C6H5-
CH3 (Na), Et2O (NaK); CH2Cl2 (P4O10). Infrared spectra were
recorded as Nujol mulls between KBr plates on a Nicolet 5PC
spectrometer. H NMR spectra (200.2 MHz) were recorded on a
Bruker DPX200 spectrometer, and 13C{1H} NMR spectra (100.55
MHz) were recorded on a Brucker DPX400 spectrometer. H and
13C{1H} NMR spectra were referenced to CHCl3 (δ ) 7.26) and
CHCl3 (δ ) 77.0), respectively. Elemental analyses were performed
by the Microanalytical service, Department of Chemistry, UMIST.
CAUTION. Most of the experiments described involve the use
of mercurial salts for the generation of diorganomercurials: These
classes of compound are known to be extremely hazardous, and
appropriate handling conditions should be used for their generation
and disposal.
1-Br-2-(CHOCH2CH2)C6H4. To a 250 mL round-bottomed
flask, fitted with a condenser and Dean and Stark trap, containing
a stirrer bar, were added toluene (100 mL), ethylene glycol (10
mL), 2-bromobenzaldehyde (25 g, 0.l35 mol), and p-toluenesulfonic
acid monohydrate (0.5 g, 2.63 mmol), and the mixture was refluxed
overnight (approximately 18 h). After cooling, the solution was
washed with NaHCO3 (50 mL, saturated) and brine (50 mL), and
the organic fraction was separated and dried over K2CO3. Filtration
of the dried solution followed by reduced-pressure distillation
afforded 2 (29.4 g, 0.128 mol, 95%); bp0.1 85-90 °C: see Table 1
for physical and analytical data.
Hg{1-C6H4-2-(CHOCH2CH2)}2. Caution! To a three-necked
250 mL round-bottomed flask, fitted with a pressure-equalizing
dropping funnel and a reflux condenser, under a N2 atmosphere
was added Mg (2.10 g, 0.86 mol), a stirrer bar THF (30 mL), and
a few crystals of I2. To this solution was added 1-Br-2-(CHOCH2-
CH2)C6H4 (20 g, 0.087 mol, THF 20 mL) from the pressure-
equalizing funnel at such a rate as to create a gentle reflux. After
addition was complete, the mixture was refluxed for an additional
1 h before cooling to 0 °C. The pressure-equalizing funnel was
then recharged with HgBr2 (27.0 g, 0.075 mol) and THF (75 mL).
This solution was added dropwise over a period of 1 h and the
reaction allowed to warm to room temperature. After stirring for
18 h, NH4Cl (30 mL, saturated) was added and the organic fraction
separated. The aqueous layer was extracted with toluene (75 mL),
and the organic fragments were combined and dried over MgSO4.
Filtration and removal of the solvent under reduced pressure
afforded 4 as an off-white solid (27.65 g, 0.055 mol, 74%) which
was pure enough for subsequent use. The analytically pure sample
(white) was obtained on recrystallization from hot EtOH: see Table
1 for physical and analytical data.
1
1
(19) Pyykko, P.; Straka, M. Phys. Chem. Chem. Phys. 2000, 2, 2489.
(20) Batsanov, S. S. J. Chem. Soc., Dalton Trans. 1998, 1541.
(21) Brookhart, M.; Green, M. L. H.; Wong, L. Prog. Inorg. Chem. 1988,
36, 1.
(22) Popelier, P. L. A.; Logothetis, G. J. Organomet. Chem. 1998, 555,
101.
(23) Banger, K. K.; Brisdon, A. K.; Brain, P. T.; Parsons, S.; Rankin, D.
W. H.; Robertson, H. E.; Smart, B. A.; Bu¨hl, M. Inorg. Chem. 1999,
38, 5894.
(24) Guillemin, J.-C.; Bellec, N.: Sze´tsi, S. K.; Nyula´szi, L.; Veszpre´mi,
T. Inorg. Chem. 1996, 35, 6586.
Hg{1-C6H4-2-(CHO)}2. Caution! To 4 (10 g, mmol) dissolved
in acetone (100 mL) in a 250 mL round-bottomed flask fitted with
Inorganic Chemistry, Vol. 41, No. 7, 2002 1911

Flower et al.
Table 5. Crystallographic Data for 6a, 6b, 6g, and 6h
6a
6b
6g
6h
chem formula
fw
C30H30HgN4
647.17
C28H24HgN2
589.08
C38H44HgN2
729.34
C30H28HgN2
617.13
T (K)
120(2)
120(2)
150(2)
120(2)
cryst syst
space group
a, Å
b, Å
c, Å
triclinic
P1h
monoclinic
P21/c
12.8260(5)
14.0675(4)
6.1032(2)
triclinic
P1h
monoclinic
P21/c
12.5307(2)
10.9852(2)
18.2112(2)
6.20000(10)
9.2315(2)
10.9069(3)
85.8510(10)
89.3570(10)
87.206(2)
621.86(2)
1
8.2626(2)
9.8317(2)
11.8873(3)
103.6650(10)
109.3350(10)
104.627(2)
825.80(3)
1
R, deg
â, deg
90.0990(10)
104.0190(10)
γ, deg
vol, Å3
Z
1101.20(6)
2
1.777
0.0285
0.0680
0.0425
0.0745
2432.15(6)
4
1.685
0.0272
0.0657
0.0313
0.0681
d(calcd), Mg/m3
R1a [I > 2σ(I)]
wR2b
1.728
0.0248
0.0601
0.0250
1.467
0.0477
0.1123
0.0488
R1 (all data)
wR2
0.0602
0.1128
a R1 ) ∑||Fo| - |Fc||/ ∑|Fo|. b Rw (F 2) ) [∑w(Fo - Fc )2/∑wFo ]1/2
.
2
2
4
a condenser was added p-toluenesulfonic acid monohydrate (0.5
g, 2.63 mmol), and the solution was refluxed for 5 h. On cooling,
the solvent volume was reduced to 10 mL and the solution poured
into rapidly stirred H2O (200 mL) containing Na2HCO3 (1 g, 0.02
mmol). The off-white precipitate of crude 5 was collected by
filtration, washed with water (50 mL), and dried. This product (7.25
g, 0.018 mol, 88%) was pure enough to use without further
recrystallization. The analytically pure sample was obtained by
recrystallization from hot EtOH: see Table 1 for physical and
analytical data.
Hg{1-C6H4-2-(CHdNC6H4-4-NMe2)}2. Caution! To 5 (1 g, 2.4
mmol) dissolved in EtOH (10 mL) containing p-toluenesulfonic
acid monohydrate (10 mg, 0.05 mmol) was added N,N-dimethy-
laniline (0.65 mL, 5.12 mmol), and the solution was refluxed for 1
h, during which time yellow crystals of 6a precipitated. The solution
was cooled and 6a collected by filtration and washed with a little
ice-cold EtOH to give an analytically pure solid (1.1 g, 1.68 mmol,
69%). See Table 1 for physical and analytical data.
All the X-ray diffraction measurements were carried out on the
National Crystallographic Service Nonius Kappa CCD diffracto-
meter, Southampton, England. Monochromatic X-rays generated
by a Nonius FR591 rotating anode source were used to record φ
scans and ω scans to fill the Ewald sphere. An Oxford cryostream
cooler was used to maintain the crystals at 150 K. The structures
were solved using direct methods and refined using full-matrix least-
squares (SHELX-97).25 Crystallographic details for compounds 6a,
6b, 6g, and 6h are presented in Table 5.
Acknowledgment. J.E.W. and S.N. thank the EPSRC for
the award of postgraduate studentships. K.R.F. thanks the
EPSRC National Crystallographic Service, Department of
Chemistry, University of Southampton, for data collections
for 6a, 6b, 6g, and 6h through Project No.01XR10 and one
of the referees for some very helpful comments.
Supporting Information Available: Four X-ray crystallo-
graphic files in CIF format. This material is available free of charge
via the Internet at http://pubs.acs.org.
Compounds 6b-h were all prepared in an analogous fashion.
See Table 1 for physical and analytical data.
Crystallography. All crystals were grown by dissolving ap-
proximately 15 mg of compound in approximately 0.3 mL of CH2-
Cl2 in a glass vial (15 × 40 mm), layering approximately 5 mL of
EtOH on top, and leaving to stand for 2 days at room temperature.
IC010881Q
(25) Sheldrick, G. M. Programs for Crystal Structure Analysis (release
97-2); University of Go¨ttingen: Go¨ttingen, 1997.
1912 Inorganic Chemistry, Vol. 41, No. 7, 2002