largely between the layers which have moved apart to accom-
modate them.16
for 5 min causing a yellow solution to form. 2-Propanol (1.5 ml)
was then added and the solution heated at 115 ꢁC under N2 for 3
days, resulting in a black suspension. Ethyl acetate (60 ml) was
added and the solution filtered through Celite to remove K2CO3,
which was further washed with more ethyl acetate (2 ꢀ 60 ml) to
give an orange solution, which was dried over MgSO4 and then
evaporated to dryness to give an orange oil. The oil was dissolved
in ethanol (50 ml) and 15% HCl (30 ml) added, before evapo-
rating to dryness again to give an orange solid. The solid was
suspended in EtOH/Et2O (50 ml/50 ml) and filtered through
a Buchner funnel to give the hydrochloride as a light orange
solid. 1H NMR (301 MHz, DMSO-d6): d (ppm) 6.50–7.50 (br s,
2H), 8.00 (dd, J ¼ 8.07, 5.32 Hz, 2 H), 8.77 (dt, J ¼ 8.26, 1.84 Hz,
2 H), 8.91 (dd, J ¼ 5.32, 1.28 Hz, 2 H), 9.32 (d, J ¼ 2.20 Hz, 2 H).
The solid was suspended in CH2Cl2 (25 ml) and NEt3 slowly
added dropwise until no solid remained before being evaporated
to dryness. Et2O (4 ꢀ 15 ml) was added and the pale orange
solution filtered through a pad of Alumina to give a pale yellow
solution which was evaporated to dryness yielding a yellow oil,
which solidified upon drying over P2O5 to give an off white solid
(1.078 g, 46%). Anal. Calc. (Found) C10H8N2$0.2H2O C 75.16
(75.14), H 5.30 (5.32), N 17.53 (17.28). MS (EI, m/z): 156 (M). 1H
NMR (301 MHz, CDCl3): d (ppm) 7.42 (ddd, J ¼ 7.94, 4.82, 0.83
Hz, 2 H), 7.89 (dddd, J ¼ 7.90, 2.39, 1.65, 0.76 Hz, 2 H), 8.66 (dd,
J ¼ 4.86, 1.65 Hz, 2 H), 8.85 (dd, J ¼ 2.39, 0.73 Hz, 2 H).
A major difference from the 4,40-bipyridine systems is in the
structure of the unsolvated selenocyanate 4, which adopts the
interesting doubly-interpenetrated network reported for {Ni
(NCS)2(3,30-bipy)2}. No interpenetrated coordination networks
have been reported for metal thio- or selenocyanate compounds
with 4,40-bipyridine, so it is possible that the greater flexibility
offered by 3,30-bipyridine allows this to occur. Unfortunately, we
have been unable as yet to grow single crystals of this structure.
Experimental
3-Bromopyridine, FeSO4$7H2O, potassium thiocyanate and
potassium selenocyanate were all purchased commercially and
used as received.
Solvated crystals were grown by the following general method,
performed in 35 ml screw-top vials: 3,30-bipyridine (0.093 g,
0.6 mmol) was dissolved in 15 ml of CHX3 and, depending upon
the density, was layered either above or below a solution of
FeSO4$7H2O (0.3 mmol) and KNCE (0.6 mmol) in 10 ml of the
second solvent (either methanol or acetonitrile, as appropriate),
which had previously been centrifuged to remove precipitated
K2SO4. The lower solution was cooled by placing the vial in ice
before layering, and a layer of the top solvent (containing no
solutes) was placed between the layers before the top layer was
added in order to prevent instant precipitation of powder.
Generally this yielded crystals of the appropriate compound at
the interface and microcrystalline powder at the bottom of the
vial.
Preparation of [Fe(NCS)2(3,30-bipy)2(MeOH)2] 1
3,30-bipy (157 mg, 1.0 mmol) was dissolved in MeOH (5 ml)
giving a pale yellow solution. In a separate flask FeSO4 (139 mg,
0.5 mmol) and KNCS (98 mg, 1.0 mmol) were mixed in MeOH
(5 ml) and then sonicated for 2 min before being centrifuged to
remove K2SO4, giving an orange solution. The Fe(NCS)2 solu-
tion was added dropwise to the 3,30-bipy solution resulting in the
precipitation of bright yellow microcrystals which were isolated
by filtration with a Buchner funnel. 218 mg, 80%. Analysis Calc.
for C24H24N6O2S2Fe: C 52.56, H 4.41, N 15.32%. Found: C
52.76, H 4.09, N 15.31%.
Crystallography
Single crystal X-ray data were collected on a Bruker APEX
diffractometer using Mo-Ka X-radiation, and corrected for
absorption using empirical methods (SADABS) based upon
symmetry-equivalent reflections combined with measurements at
different azimuthal angles. Crystal structures were solved and
refined against all F2 values using the SHELXTL suite of
programs.22 Non-hydrogen atoms were refined anisotropically
and hydrogen atoms were placed in calculated positions refined
using idealized geometries (riding model) and assigned fixed
isotropic displacement parameters. Crystallographic details are
contained in Table 2, and .cif files for all structures form part of
the ESI. Within the crystal structure of 4$2CHBr3 there is some
rotational disorder of both the solvent molecule and the pyridyl
rings, which contributes to an R-factor of 6.25%. The structures
of 3$2CHCl3 and 3$2CHBr3 also contain disordered solvent
molecules.
Preparation of [Fe(NCSe)2(3,30-bipy)2(MeOH)2] 2
3,30-bipy (157 mg, 1.0 mmol) was dissolved in MeOH (5 ml)
giving a pale yellow solution. In a separate flask FeSO4 (139 mg,
0.5 mmol) and KNCSe (144 mg, 1.0 mmol) were mixed in MeOH
(5 ml) and then sonicated for 2 min before being centrifuged to
remove K2SO4 giving a yellow solution. The Fe(NCSe)2 solution
was added dropwise to the 3,30-bipy solution, resulting in the
precipitation of yellow microcrystals which were isolated by
filtration with a Buchner funnel (244 mg, 76%). Analysis Calc.
for C24H24N6O2Se2Fe: C 44.88, H 3.77, N 13.09%. Found: C
44.65, H 3.82, N 12.78%.
Powder X-ray diffraction data were collected on a Bruker D8
advance powder diffractometer, operating at room temperature
in reflection mode. The indexing of the powder pattern of 4 was
performed using DASH.23
Preparation of 2D [Fe(NCS)2(3,30-bipy)2] 3
3,30-bipy (94 mg, 0.6 mmol) was dissolved in MeCN (8 ml) giving
a colourless solution. In a separate flask FeSO4 (84 mg,
0.3 mmol) and KNCS (59 mg, 0.6 mmol) were mixed in MeCN
(10 ml) and then sonicated for 2 min before being centrifuged to
remove K2SO4, giving a red solution. The Fe(NCS)2 solution was
added dropwise to the 3,30-bipy solution, resulting in the
Preparation of 3,30-bipyridine
Pd(OAc)2 (0.337 g, 1.5 mmol), [n-Bu4N]Br (4.837 g, 15 mmol)
and K2CO3 (4.140 g, 30 mmol) were dissolved in degassed DMF/
H2O (7 ml/3 ml) to give an orange solution. 3-Bromopyridine
(2.95 ml, 30 mmol) was added and the solution heated to 115 ꢁC
This journal is ª The Royal Society of Chemistry 2011
CrystEngComm, 2011, 13, 4909–4914 | 4913