using the halogeno ether (CH2OCH2CH2Cl)2. Yield: 0.263 g,
10 Quantitative yield. NMR (CDCl3, 25 ЊC): 1H (200 MHz),
1
18%. NMR (CDCl3, 25 ЊC): H (200 MHz), δ 7.38 (dd, 2 H),
δ 7.50 (dd, 2 H), 7.04 (dd, 2 H) and 2.01 (s, 2 H). Mass spec-
7.12 (dd, 2 H), 3.66 (m, 20 H) and 3.05 (t, 4 H); 77Se
trum: m/z 236 (M+ Ϫ 2, 48%).
(57.24 MHz), δ 263. Mass spectrum: m/z 538 (M+, 15), 387
14 Yield: 0.16 g, 22% (ii) (Found: C, 41.45; H, 4.85.
C25H34O5Se4 requires C, 41.10; H, 4.65%), m.p. 88 ЊC. NMR
(CDCl3, 25 ЊC): 1H (200 MHz), δ 7.41 (dd, 2 H), 7.18 (t, 1 H),
7.11 (dd, 2 H), 6.85 (dd, 1 H), 6.66 (dd, 1 H), 3.74 (m, 8 H), 3.59
(s, 8 H), 3.39 (s, 3 H) and 3.05 (m, 8 H); 13C-{1H} (50.3 MHz),
δ 135.0, 132.5, 130.3, 127.4, 119.8, 107.7, 70.5, 52.8 and 27.3; 77Se
(95.41 MHz), δ 286, 271, 270 and 180. Mass spectrum: m/z 732
+
[M Ϫ (CH2CH2O)2CH2CH2Cl, 12] and 236 (C6H4Se2 , 24%).
C6H4[SeCH2CH2(OCH2CH2)2OCH2CH2X]2-1,2 (X = Cl
3
or Br 4). The synthesis of 3 and 4 was performed as for 1 with
the appropriate halogeno ether, (ClCH2CH2OCH2CH2)2O and
(BrCH2CH2OCH2CH2)2O, respectively.
3 Yield: 0.255 g, 15%. NMR (CDCl3, 25 ЊC): 1H (200 MHz),
δ 7.39 (dd, 2 H), 7.13 (dd, 2 H), 3.79 (t, 4 H), 3.73 (t, 4 H), 3.63
(m, 16 H), 3.55 (t, 4 H), 3.06 (t, 4 H); 77Se (57.24 MHz),
δ 263. Mass spectrum: m/z 626 (M+, 20), 431 [M Ϫ (CH2-
+
+
(M+, 82), 264 (H3COC6H4Se2 , 88) and 236 (C6H4Se2 , 100%).
Synthesis of the mercury complexes
To a thf (12 cm3) solution of the macrocycle 6–8 (0.108
mmol) was added dropwise at 25 ЊC a thf (6 cm3) solution of
HgI2 (0.098 g, 0.216 mmol). The reaction mixture was then
stirred for 40 h. The solvent was removed and the residue was
recrystallized from toluene.
15 Yield: 0.112 g, 68% (Found: C, 16.05; H, 1.75. C20H24-
Hg2I4O2Se4 requires C, 15.80; H, 1.60%). NMR (CDCl3, 25 ЊC):
1H (200 MHz), δ 7.54 (dd, 4 H), 7.23 (dd, 4 H), 3.85 (t, 8 H) and
3.32 (t, 8 H); 13C-{1H} (50.3 MHz), δ 134.9, 133.6, 128.6, 69.5
and 32.0.
16 Yield: 0.124 g, 71% (Found: C, 18.15; H, 2.10. C24H32-
Hg2I4O4Se4 requires C, 17.90; H, 2.00%). NMR (CDCl3, 25 ЊC):
1H (200 MHz), δ 7.52 (dd, 4 H), 7.21 (dd, 4 H), 3.84 (t, 8 H),
3.62 (s, 8 H) and 3.27 (t, 8 H); 13C-{1H} (50.3 MHz), δ 134.8,
133.7, 128.7, 70.0 and 32.0; 77Se (95.41 MHz), δ 198.5.
17 Yield: 0.15 g, 82% (Found: C, 20.10; H, 2.50. C28H40-
Hg2I4O6Se4 requires C, 19.80; H, 2.35%). NMR (CDCl3, 25 ЊC):
1H (200 MHz), δ 7.54 (dd, 4 H), 7.23 (dd, 4 H), 3.85 (t, 8 H) and
3.32 (t, 8 H); 13C-{1H} (50.3 MHz), δ 134.9, 133.6, 128.6, 69.5
and 32.0; 77Se (95.41 MHz), δ 184.5.
+
CH2O)3CH2CH2Cl, 20] and 236 (C6H4Se2 , 24%).
4 Yield: 0.253 g, 13%. NMR (CDCl3, 25 ЊC): 1H (200 MHz),
δ 7.39 (dd, 2 H), 7.14 (dd, 2 H), 3.80 (t, 4 H), 3.74 (t, 4 H), 3.64
(m, 16 H), 3.46 (t, 4 H) and 3.07 (t, 4 H); 77Se (57.24 MHz),
δ 262. Mass spectrum: m/z 714 (M+, 30), 475 [M Ϫ (CH2-
+
CH2O)3CH2CH2Br, 11] and 236 (C6H4Se2 , 29%).
Synthesis of the tetraselena macrocycles
Method (i). To thf (170 cm3) preheated to reflux were slowly
added over 8 h a solution of dichloroselenoether 1–3 (1.27 mmol)
in thf (20 cm3) and a solution of dipotassium benzene-1,2-
diselenolate 5 (0.39 g, 1.27 mmol) in thf (20 cm3). The reaction
mixture was refluxed for 12 h. The solvent was removed in vacuo
and the residue obtained was purified by flash chromatography
on a silica gel column eluted with pentane–diethyl ether.
Method (ii). Under argon, a solution of the (benzene-1,2-
diselenolato)zirconocene 9 (0.57 g, 1 mmol) in thf (25 cm3) was
treated at room temperature with a solution of HCl gas in thf
until the solution became colourless. After removal of the sol-
vent, the residue was extracted with pentane (20 cm3) then fil-
tered. The solvent was evaporated under vacuum, the benzene-
1,2-diselenol 10 (0.24 g, 1 mmol) thus obtained was dissolved in
methanol (50 cm3) and caesium carbonate (0.33 g, 1 mmol) was
added. When the caesium carbonate was completely dissolved,
the methanol was removed and dimethylformamide (dmf) (5
cm3) and then the dichloroselenoether 1–3 (1 mmol) were added.
The final suspension was stirred at 65 ЊC for 4 d. The solvent
was removed in vacuo and the residue was dissolved in CH2Cl2
(20 cm3) and a solution of KOH (20 cm3, 10%). The organic
layer was washed twice with KOH solution (20 cm3, 1%) then
dried over MgSO4. After the removal of the solvent the residue
was purified by flash chromatography (silica, eluent: pentane–
diethyl ether).
X-Ray analyses of compounds 7 and 17
Yellow crystals of these compounds suitable for diffraction
measurements were grown from CH2Cl2–hexane (1:1) (com-
pound 7) or toluene (compound 17) solutions. The unit-cell
determinations and data collections were carried out on an
Enraf-Nonius CAD4 diffractometer. The pertinent crystallo-
graphic data are given in Table 1. All calculations were per-
formed using the MOLEN package15 with neutral-atom
scattering factors. Intensities were corrected for Lorentz and
polarization effects. A lack of systematic extinctions indicated
¯
either centrosymmetric P1 or non-centrosymmetric P1 triclinic
space group. Both structures were solved by Patterson and sub-
sequent Fourier-difference syntheses. After isotropic refinement
of the models the hydrogen atoms were placed in calculated
positions, and an empirical absorption correction (DIFABS16)
was applied for both structures. All non-hydrogen atoms were
further refined with anisotropic thermal parameters. The
hydrogen atoms were included in a riding model with Biso fixed
at 1.3Beq for the carbon atoms bearing them. Final residuals
are given in Table 1. Atomic scattering factors and anomalous
dispersion coefficients were taken from the usual sources.17
Atomic coordinates, thermal parameters, bond lengths and
angles have been deposited at the Cambridge Crystallographic
Data Centre (CCDC). See Instructions for Authors, J. Chem.
Soc., Dalton Trans., 1997, Issue 1. Any request to the CCDC for
this material should quote the full literature citation and the
reference number 186/372.
The macrocycle 14 has been synthesized following method
(ii), starting from complex 12 (0.599 g, 1 mmol).
6 Yield: 0.06 g, 10% (i); 0.11 g, 18% (ii) (Found: C, 39.50;
H, 3.85. C20H24O2Se4 requires C, 39.20; H, 3.90%), m.p.
139 ЊC. NMR (CDCl3, 25 ЊC): 1H (200 MHz), δ 7.38 (dd, 4 H),
7.10 (dd, 4 H), 3.76 (t, 8 H) and 3.03 (t, 8 H); 13C-{1H}
(50.3 MHz), δ 135.0, 132.8, 127.6, 70 and 27.6; 77Se (57.24
MHz), δ 278. Mass spectrum: m/z 610 (M+, 30) and 236
+
(C6H4Se2 , 75%).
7 Yield: 0.13 g, 18% (i); 0.18 g, 25% (ii) (Found: C, 41.45; H,
4.50. C24H32O4Se4 requires C, 41.15; H, 4.55%), m.p. 109 ЊC.
1
NMR (CDCl3, 25 ЊC): H (200 MHz), δ 7.39 (dd, 4 H), 7.10
(dd, 4 H), 3.77 (t, 8 H), 3.59 (s, 8 H) and 3.06 (t, 8 H); 13C-{1H}
(50.3 MHz), δ 134.8, 132.0, 127.4, 70.5 and 27.4; 77Se (57.24
MHz), δ 268. Mass spectrum: m/z 700 (M+, 20) and 236
+
(C6H4Se2 , 100%).
8 Yield: 0.20 g, 25% (i); 0.32 g, 40% (ii) (Found: C, 42.95; H,
5.00. C28H40O6Se4 requires C, 42.65; H, 5.10%), m.p. 93 ЊC.
NMR (CDCl3, 25 ЊC): 1H (200 MHz), δ 7.38 (dd, 4 H), 7.10 (dd,
4 H), 3.74 (t, 8 H), 3.60 (s, 20 H) and 3.05 (t, 8 H); 13C-{1H}
(50.3 MHz), δ 134.6, 132.0, 127.4, 70.5 and 27.0; 77Se
(57.24 MHz), δ 265. Mass spectrum: m/z 788 (M+, 20%).
Results and Discussion
Synthesis of the tetraselena macrocycles
The tetraselenacrown ethers 6–8 were prepared from the dihal-
ogeno selenoethers 1–4 and dipotassium benzene-1,2-diseleno-
1044
J. Chem. Soc., Dalton Trans., 1997, Pages 1043–1048