leads to formation of a green solution. Removal of the solvent
in vacuo gives an orange solid which may be redissolved in CH Cl
green solution) and layered with hexane to give orange crystals.
Microanalyses on the isolated solid are consistent with a 1 : 1 Co :
either one or two mol. equiv. of the dithioether MeS(CH
2
)
3
SMe
2
2
(which would in principle give rise to a similar six-membered
2
(
chelate ring as in [CoI
to an intractable oil.
2
n
(L )] ) under similar conditions led only
2
thioether ratio, and hence the formulation [CoI
2
(L )]. However,
These results demonstrate the importance of the ligand archi-
tecture and the reaction conditions in directing the coordination
of thioether ligands to unusual Co(II) complexes and illustrate
some of the unexpected features still to be discovered in this area
of chemistry.
while the solution UV-visible spectrum is consistent with tetra-
hedral high spin Co(II), the diffuse reflectance spectrum (solid)
shows an octahedral Co(II) species. To establish definitively the
coordination environment, a crystal structure determination was
undertaken. The structure reveals (Fig. 2) a distorted octahedral
coordination sphere at Co(II), comprising mutually trans iodo
ligands, with two cis-chelating tetrathioether ligands. The other
two thioether donors then bridge to another Co atom producing
an infinite chain polymer. The S–Co–S chelate angles are 85.20(2)
Acknowledgements
We thank the EPSRC for funding (EP/C528824/1).
◦
and 85.73(2) .
Notes and references
†
All reactions were performed under an atmosphere of dry nitrogen using
standard Schlenk techniques and appropriately dried solvents.
1
◦
L : To a flask containing 200 mL NH
3
(l) at −78 C was added 0.76 g
(
2 2
33.2 mmol) of Na in small pieces, followed by 1.5 mL (17.3 mmol) of Me S
slowly via syringe, giving a colourless solution. The NH
under a stream of N and the resulting NaSMe was dissolved in 10 mL
of dry EtOH and heated to reflux. 1,2,4,5-Tetrakis(bromomethyl)benzene
3.00 g, 6.67 mmol) dissolved in dry EtOH (ca. 250 mL) was added via
cannula over ca. 30 min and the resulting mixture was refluxed overnight.
After quenching with 100 mL of saturated NaHCO (aq) and extracting
with CH Cl
(3 × 200 mL), the organic phase was collected, washed with
00 mL brine, dried (MgSO ), filtered and the volatiles removed under
3
was evaporated
2
(
Fig.
CoI
2
View of
a portion of the infinite chain structure of
}] with atom numbering scheme. Ellipsoids are shown
[
2
{C(CH SMe)
2
4
3
at the 50% probability level. Symmetry operation: a = x + 1, y, z.
Selected bond lengths and angles: Co1–S3a = 2.5104(7), Co1–S1 =
2
2
1
4
vacuum. Upon removal of most of the volatiles the product precipitated
as a white solid which was collected by filtration, washed with hexane and
dried under vacuum. A second crop of crystalline product was collected by
2
.5201(7), Co1–S4a = 2.5375(7), Co1–S2 = 2.5471(7), Co1–I1 = 2.7463(4),
Co1–I2 = 2.7913(4) A˚ ; S3a–Co1–S1 = 178.19(2), S3a–Co1–S4a =
1
8
8
9
8
9
5.20(2), S1–Co1–S4a = 93.24(2), S3a–Co1–S2 = 95.85(2), S1–Co1–S2 =
5.73(2), S4a–Co1–S2 = 178.40(2), S3a–Co1–I1 = 90.07(2), S1–Co1–I1 =
0.84(2), S4a–Co1–I1 = 89.67(2), S2–Co1–I1 = 89.12(2), S3a–Co1–I2 =
9.76(2), S1–Co1–I2 = 89.32(2), S4a–Co1–I2 = 90.11(2), S2–Co1–I2 =
combining the hexane washings with the CH Cl . Yield: 1.85 g, 87%. H-
2
2
NMR d(CDCl
3
): 2.05 (12H, s, Me), 3.81 (8H, s, CH
CH). C{ H}-NMR d(CDCl ): 15.6 (Me), 35.2 (CH
CH), 135.2 (aromatic quaternary). CIMS: found m/z = 319 (M ).
Required for C14 O: C, 49.45; H, 7.19. Found: C, 49.95; H,
·H
.19%.
CoI SMe) }]: To
{o-C
(0.32 mmol) of dry CoI dissolved in ca. 15 mL of BuOH was added
2
), 7.13 (2H, s, aromatic
13
1
3
2
), 133.0 (aromatic
+
H
22
S
4
2
◦
1.10(2), I1–Co1–I2 = 179.74(1) .
7
[
2
6
H
4
(CH
2
2
a Schlenk tube containing 0.10 g
n
The Co–S bond distances are in the range 2.5104(7)
˚
2
o-C
6
H
4
(CH
2
SMe) (0.063 g, 0.32 mmol) dissolved in approximately
2
Cl by cannula. The blue reaction mixture was stirred at
2
to 2.5471(7) A, considerably longer than in [CoI
2
{o-
1
0 mL of CH
2
C
6
H
4
(CH
2
SMe)
2
}] above, reflecting the lower coordination num-
room temperature for 48 h. Volatiles were removed under vacuum and
the residue was dissolved in CH Cl . The green solution was layered with
hexane to give the product as green crystals. Yield: 0.65 g, 50%. leff. = 4.3
. UV-vis (nm) (dr): 774, 710, 660, 385. UV-vis (nm) (CH Cl ): 766 (emol
160 mol cm dm ), 702 (818), 658 (415). Required for C10 14CoI
C, 23.5; H, 2.76. Found: C, 23.6; H, 2.77%.
[CoBr {o-C H (CH SMe) }]: prepared similarly. Blue–green solid. Yield
ber in the latter (tetrahedral) species. These Co–S bond distances
are also significantly longer than in the Co(II) thiamacrocyclic
species (vide supra), mainly reflecting the different spin state in
these cations. Magnetic measurements on [CoI
solid and in solution show that the products involve high spin
Co(II). Like [CoI
to the conclusion that this species also undergoes a rare and
reversible structural rearrangement (isomerisation), whereupon
dissolution in BuOH or CH
2
2
l
1
B
2
2
=
2 2
−
1
−1
3
H
S :
2
2
(L )] both in the
2
6
4
2
2
1
75%. l = 4.4 l . UV-vis (nm) (dr): 725, 670, 628; (CH Cl ): 725 (e
=
(L )], consideration of these UV-visible data led
eff.
−
B
2
2
mol
2
1
−1
3
3
27 mol .cm .dm ), 653 (368), 609 (204). IR (Nujol): m(CoBr) = 266
−1
2 2
(
br) cm . Required for C10
H
14Br
CoS
·1/3BuOH: C, 30.8; H, 4.0. Found:
C, 30.6; H, 3.4%.
[CoI
(
n
1
(L )]: prepared similarly. Yellow solid. Yield 40%. UV-vis
2
Cl
2
causes the polymer to break up
core,
2
nm) (dr): 770, 704, 478, 362. UV-vis (nm) (CH Cl
2
2
): 766 (emol
=
into discrete monomer units involving a tetrahedral CoI
2
S
2
−
1
−1
3
8
50 mol cm dm ), 702 (800), 661 (600), 434 (1430), 358 (1810). Required
and this then reassembles to the polymer chain with octahedral
Co(II) in the solid (Scheme 1). This process may be driven by the
lower solubility of the latter.
for C14
H
22CoI
2
S
4
·1/4BuOH: C, 27.7; H, 3.58. Found: C, 27.5; H, 3.7%.
1
1
[I Co(L )CoI ]: prepared similarly, but using a 2 : 1 CoI : L ratio. Green
2
2
2
solid. Yield 54%. leff. = 4.8 l
UV-vis (nm) (CH Cl
molar extinction coefficient could not be determined reliably). Required
: C, 17.8; H, 2.4. Found: C, 17.0; H, 1.8%.
(L )]: To a Schlenk tube containing 0.30 g (0.96 mmol) of dry CoI
B
. UV-vis (nm) (dr): 763, 706, 650, 463, 364.
2
2
): 734, 708, 656 (sample not very soluble, hence
for C14
2 4 4
H22Co I S
2
[
CoI
2
2
−1
n
dissolved in ca. 25 mL of BuOH was added 2.6 mL of a 0.095 g mL
2
solution of L . The reaction mixture was stirred at room temperature
overnight, volatiles were removed under vacuum to give an orange solid.
Scheme
1
Showing the interconversion between the octahedral
2
2
The solid was dissolved in CH
hexane to give orange crystals. After removal of the volatiles the orange
solid was extracted with CH Cl (20 mL), filtered, the volume of the green
2 2
Cl to give a green solution and layered with
[
CoI
2
(L )]
n
polymer and the discrete tetrahedral [CoI
2
(L )] monomers.
2
2
Successful isolation of the Co(II) species described here appears
to be very finely balanced and we note that reaction of CoI with
solution was reduced to approximately 5 mL and the solid was precipitated
by adding 40 mL hexane, isolated by filtration and dried under vacuum.
2
This journal is © The Royal Society of Chemistry 2007
Dalton Trans., 2007, 1986–1988 | 1987