2-Amino-4-(2-pyridyl)thiazole as chelating ligand: A dinuclear oxido-bridged ferric complex and mononuclear 3d metal complexes

Article abstract of DOI:10.1002/ejic.201400041

2-Amino-4-(2-pyridyl)thiazole (H₂L) complexes of iron(III), iron(II), cobalt(II), nickel(II) and copper(II) have been prepared for the first time. The oxido-bridged dinuclear ferric complex [(H₂L) ₂FFe^III(μ-O)Fe^IIIF(H₂L) ₂](BF₄)₂ (1) and the mononuclear difluorido complex [Fe^III(H₂L)₂F₂](BF ₄) (2) were prepared with Fe(BF₄)₂· 6H₂O. Complex 1 contains strong antiferromagnetically coupled iron(III) ions. In addition, the mononuclear 3:1-type complex [Co(H ₂L)₃](ClO₄)₂ (3) and the mononuclear 2:1-type complexes [Cu(H₂L)₂](ClO₄) ₂ (4) and [M(H₂L)₂(NCX)₂] (5: M = Fe, X = S; 6: M = Fe, X = Se; 7: M = Co, X = S; 8: M = Ni, X = S) were prepared. Copyright

Full text of DOI:10.1002/ejic.201400041

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DOI:10.1002/ejic.201400041
2
-Amino-4-(2-pyridyl)thiazole as Chelating Ligand:
A Dinuclear Oxido-Bridged Ferric Complex and
Mononuclear 3d Metal Complexes
[
a]
[a]
[b]
[c]
Timo Huxel, Selina Leone, Yanhua Lan, Serhiy Demeshko,
and Julia Klingele*[
a]
Keywords: N ligands / Chelates / Nitrogen heterocycles / Iron / Fluorides
2
-Amino-4-(2-pyridyl)thiazole (H
2
L) complexes of iron(III),
antiferromagnetically coupled iron(III) ions. In addition, the
mononuclear 3:1-type complex [Co(H L) ](ClO (3) and the
mononuclear 2:1-type complexes [Cu(H L) ](ClO (4) and
[M(H L) (NCX) ] (5: M = Fe, X = S; 6: M = Fe, X = Se; 7: M
iron(II), cobalt(II), nickel(II) and copper(II) have been
prepared for the first time. The oxido-bridged dinuclear ferric
2
3
4 2
)
2
2
4 2
)
III
III
complex [(H
2
L)
2
FFe (μ-O)Fe F(H
2
III
L)
2
](BF
4
)
F
2
(1) and the
](BF ) (2) were
4 2 2
prepared with Fe(BF ) ·6H O. Complex 1 contains strong
2
2
2
mononuclear difluorido complex [Fe (H
2
L)
2
2
4
= Co, X = S; 8: M = Ni, X = S) were prepared.
Introduction
SCO complexes of iron(II). Often such SCO complexes are
II az
az
of the mononuclear [Fe (L ) (Y) ] type, in which L is
2
2
[1]
The phenomenon of spin crossover (SCO) in complexes a 2-pyridyl-substituted azole and Y an anionic co-ligand.
4
7
II az
of 3d –3d transition-metal ions has been intensively However, SCO complexes of the type [Fe (L )
]X , with X
2
3
studied over the last few decades, with a special focus on being a non-coordinating anion, are also known and have,
[
2–7]
iron(II) complexes.
As a result, a great variety of iron(II) for example, been prepared with the ligands 2-methyl-4-
SCO compounds have been reported,[
feature 2-pyridyl-substituted azole ligands, for example, 4- (V).
substituted 3,5-di(2-pyridyl)-4H-1,2,4-triazoles,
8–12]
many of which (2-pyridyl)thiazole (IV) and 4-methyl-2-(2-pyridyl)thiazole
[
28]
[
13–17]
re-
In the course of our studies on complexes of the related
[
18–20]
lated di(2-pyridyl)-substituted chalcadiazoles
or 2-pyr- ligand 2-amino-4-(2-pyridyl)thiazole (H L, Figure 1,
2
idyl-substituted triazolopyridines.[
21,22]
In addition to these b),
[32,33]
we observed the unexpected formation of an oxido-
triazole- and diazole-based ligands, similar thiazole-based bridged diiron(III) complex instead of the expected mono-
[
23–31]
ligands (Figure 1)
have also been used to prepare nuclear iron(II) complex. Such dinuclear oxido-bridged
[
24,26,31,40]
Figure 1. a) 2-Pyridyl-substituted thiazole ligands that form ferrous SCO compounds: 2,4-di(2-pyridyl)thiazole (I),
2-(2-pyr-
[25,27,41]
[29,30]
[28]
idylamino)-4-(2-pyridyl)thiazole (II),
2-(2-pyrazylamino)-4-(2-pyridyl)thiazole (III),
4-(2-pyridyl)-2-methylthiazole (IV),
2
-(2-pyridyl)-4-methylthiazole (V);[ b) 2-amino-4-(2-pyridyl)-thiazole (H
28]
2
L).
iron(III) complexes are of special interest as model com-
[
a] Institut für Anorganische und Analytische Chemie, Albert-
Ludwigs-Universität Freiburg,
pounds for O -binding non-haem enzymes. Often their
2
Albertstr. 21, 79104 Freiburg, Germany
E-mail: julia.klingele@ac.uni-freiburg.de
http://www.coordchem.de
active site comprises a dinuclear iron centre, to which O2
binds in the first step to the reduced iron(II) centre to form
a diiron(III) peroxo species. It has been proposed that in a
number of diiron enzymes this intermediate decays by cleav-
[b] Institut für Anorganische Chemie, Karlsruher Institut für
Technologie (KIT),
Engesserstr. 15, Geb. 30.45, 76131 Karlsruhe, Germany
[
c] Institut für Anorganische Chemie, Georg-August-Universität age of the O–O bond and generation of an oxido-bridged
Göttingen,
[34]
intermediate.
The understanding of the geometry, elec-
Tammannstr. 4, 37077 Göttingen, Germany
Supporting information for this article is available on the
WWW under http://dx.doi.org/10.1002/ejic.201400041.
tronic structure and reactivity of the active site has bene-
fited from an increased number of syntheses of such spe-
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cies.[35–38] This type of complex is also of special interest for methoxy-2-methylpropane) for further investigation of its
their chemistry and magnetic behaviour.[
36,39]
Following this magnetic properties. The reproducible formation of oxido-
line, we have investigated the coordination behaviour of li- bridged species was indicated by mass spectroscopy (see
gand H L towards divalent 3d transition-metal ions to Figure S1 in the Supporting Information) and elemental
2
throw light not only on the bioinorganic aspect of its com- analysis.
plexes but also on the possibility of designing SCO com-
plexes of this ligand.
However, in MeOH solution under otherwise identical
reaction conditions, the application of TBME vapour dif-
fusion resulted in the formation of the mononuclear ferric
III
complex [Fe (H L) (F) ](BF )·1.25MeOH (2·1.25MeOH)
2
2
2
4
Results and Discussion
(Figure 3, Scheme 1), isolated as a sesquihydrate after dry-
II
In light of the 3:1-type SCO complexes [Fe (IV) ]X · ing in vacuo. Unexpectedly, in both cases fluoride was ab-
3
2
II
nH O (X = ClO , n = 1; X = BF , n = 0) and [Fe (V) ]X
X = ClO , BF ), ligand H L was treated with Fe(BF ) · oxidised to form the dinuclear oxido-bridged ferric complex
stracted from the tetrafluoroborate anion and iron(II) was
2
4
4
3
2
[
28]
(
4
4
2
4 2
6
H O in a 3:1 molar ratio in MeOH or MeCN. No solid 1 or the mononuclear ferric complex 2, respectively. The
2
material formed on keeping the two reaction mixtures in an two complexes were also formed by using the correct 2:1
inert argon atmosphere for several days. After evaporation ligand-to-metal-salt stoichiometry, but no product was ob-
of the solvent in air, each reaction mixture formed a red tained by conducting the reactions in an inert gas atmo-
III
III
crystalline solid identified as [(H L) FFe (μ-O)Fe F- sphere. A number of publications have previously reported
2
2
(
H L) ](BF ) ·1.25MeOH (1·1.25MeOH, Scheme 1 and that the BF4– ion may react with the ligand and metal ion,
2 2 4 2
Figure 2) and 1·MeCN, respectively, by single-crystal X-ray resulting in fluoride abstraction and its coordination to the
diffraction analysis. Dinuclear μ-oxido-bridged ferric com- metal ion. In 1982, Reedijk summarised these findings and
plexes such as 1 have attracted considerable attention in the formulated that under ambient conditions, apart from a
past, not only for their distinctive magnetic and spectro- fluorido transition-metal complex, a BF ·L adduct (L =
3
[
39,42]
[46]
scopic properties.
The interactions of such complexes monodentate ligand) is also formed in the process.
with diiron non-haem proteins such as hemeerythrin, meth-
ane monooxygenase, ribonucleotide reductase and purple single-crystal X-ray diffraction analysis as [Co (H L) ]-
A mononuclear 3:1-type complex of H L, identified by
2
II
2
3
acid phosphatases have been studied in detail, especially in (ClO ) ·1.5MeOH·0.25H O (3·1.5MeOH·0.25H O), was
4
2
2
2
the field of bioinorganic chemistry.[
39,43–45]
Solvent-free obtained by treating Co(ClO ) ·6H O with 3 equiv. of H L
4 2 2 2
bulk material of 1 was obtained from MeCN by TBME in MeOH (Figure 4 and Scheme 1). Bulk material of 3·H O
2
vapour diffusion (TBME = tert-butyl methyl ether = 2- was obtained by drying the orange crystalline solid of
II
Scheme 1. Synthesis of complexes [(H
2
L)
2
FFeIII(μ-O)FeIIIF(H
2
L)
2
](BF
4
)
2
(1), [FeIII(H
2
L)
] (7) and [Ni (H
O, MeOH; iv) Co(ClO
2
F
2
](BF
4
) (2), [Co (H
2
L)
] (8). Reagents
·6H O, MeOH;
3 4 2
](ClO ) (3),
II
II
II
II
II
[
Cu (H
and conditions: i) Fe(BF
v) Cu(ClO ·6H O, MeOH; vi) “M(NCS)
2
L)
2
](ClO
4
)
2
(4), [Fe (H
2
L)
2
(NCS)
2
] (5), [Fe (H
2
L)
2
(NCSe)
2
] (6), [Co (H
2
L)
2
(NCS)
·6H
2
”, MeOH or MeCN.
2
2 2 2
L) (NCS)
4
)
2
·6H
2
O, MeCN; ii) TBME vapour diffusion; iii) Fe(BF
”, MeOH; vii) “Fe(NCSe)
4
)
2
2
4
)
2
2
4
)
2
2
2
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III
III
[48]
3
·1.5MeOH·0.25H O in vacuo. Applying the same reaction [(bpmen)FFe (μ-O)Fe F(bpmen)](ClO )
and [(TPyA)-
2
4 2
III
III
[49]
conditions, but by using Cu(ClO ) ·6H O, a 2:1-type com- FFe (μ-O)Fe F(TPyA)](BF ) ,
a trans coordination
4
2
2
4 2
plex was formed, identified by elemental analysis as with respect to the Fe–O–Fe moiety is found [bpmen and
II
[
Cu (H L) ](ClO ) (4, Scheme 1), whereas no isolable TPyA are the tetradentate N ligands N,NЈ-dimethyl-N,NЈ-
2
2
4
2
4
compound was formed by using Ni(ClO ) ·6H O or bis(2-pyridylmethyl)ethane-1,2-diamine and tris(2-pyr-
4
2
2
Fe(ClO ) ·6H O.
idylmethyl)amine, respectively]. In similar complexes of
4
2
2
Apart from the [Fe(L) ]X complexes mentioned pre- bpmen with other monodentate co-ligands such as chlor-
3
2
[
50,51]
[48]
[48]
viously, SCO complexes of 2-pyridyl-substituted azole li- ide,
acetate
or fluoride/acetate,
these are also usually coordinated trans with
Therefore H L was treated with “Fe(NCS) ” respect to the Fe–O–Fe moiety. A similar staggered coordi-
or of TPyA and
II
[52]
gands often have the composition [Fe (L) (NCX) ] (X = S chloride,
2
2
[
13,47]
or Se).
and “Fe(NCSe) ” in 2:1 molar ratios. Under an inert gas nation of the co-ligands, however, is found in the similar
2
2
2
II
III
III
atmosphere, [Fe (H L) (NCS) ] (5, Figure 5) and oxido-bridged ferric complexes [(L) ClFe (μ-O)Fe Cl-
Fe (H L) (NCSe) ] (6, Figure S2 in the Supporting Infor- (L)2] (L = 2,2Ј-bipyridine
mation) were isolated from MeOH and MeCN solution as idine).
2
2
2
2
II
2+
[53]
[
or 4,4Ј-dimethyl-2,2Ј-bipyr-
2
2
2
[
54]
The Fe–O–Fe moiety in 1·1.25MeOH [157.7(1)°]
brown compounds, respectively, and identified by single- and 1·MeCN [156.9(3)°] is unusually bent compared with
[
48,50,51]
[49,52]
crystal X-ray diffraction analyses. Both complexes exhibit the complexes of bpmen,
TPyA,
2,2Ј-bipyr-
[
53]
[54]
cis-coordinated co-ligands, a motif that has not been ob- idine
or 4,4Ј-dimethyl-2,2Ј-bipyridine
but is viously, but is within the range found for other Fe–O–Fe-
The Fe–O distances [1.825(2),
Hence complexes [Co (H L) (NCS) ] (7, Fig- 1.815(2) and 1.819(4), 1.806(4)° for 1·1.25MeOH and
mentioned pre-
[18–21]
served before in our studies of related ligands,
not unknown for 2-pyridyl-substituted azole-based li- bridged complexes.
[
39,42]
[
13]
II
gands.
2
2
2
II
ure S3) and [Ni (H L) (NCS) ] (8, Figure S4) were synthe- 1·MeCN, respectively] are characteristic of singly oxido-
2
2
2
”
[39,42]
sised with “M(NCS)2 (M = Co, Ni) in MeOH solution. X- bridged ferric complexes.
A small trans influence is ob-
III
ray diffraction analyses revealed the cis-coordination of the served with Fe –N distances trans to the oxido-bridge
py
co-ligands in both cases.
being somewhat longer [2.267(3)–2.290(5) Å] than those
trans to the F ions [2.170(3)–2.180(6) Å]. The Fe –F dis-
–
III
tances [1.893(2)–1.918(2) Å] are comparable to those of the
Description of the Crystal Structures
[
48]
difluorido complexes of bpmen [1.843(3) Å]
Compounds 1·1.25MeOH and 1·MeCN both crystallise [1.849(2), 1.892(2) Å]. Intramolecular π–π stacking is ob-
and TPyA
[
49]
¯
in the triclinic space group P1 with one complex cation, served in both complexes of 1·solvent between the pyridyl
two (disordered) tetrafluoroborate counter ions and par- ring trans to the fluorido co-ligand and the thiazole ring
tially occupied MeOH molecules adding up to 1.25 or one of the corresponding ligand of the neighbouring half mole-
fully occupied MeCN solvent molecule, respectively. The cule. Also, a multitude of intramolecular N–H···F and
complex cations of the two compounds are isostructural N–H···O bonds are apparent. A common intermolecular –
III
III
2+
and best described as [(H L) FFe (μ-O)Fe F(H L) ] , (N–H···F···H–N–H···F···H) ring motif (Figure 2, b) leads to
2
2
2
2
III
consisting of two oxido-bridged [Fe (H L) F] fragments dimers of dinuclear complexes. In 1·1.25MeOH, two
2
2
with a distorted octahedral N OF coordination of the ferric Sta···Sta short contacts further connect these dimeric units
4
ions and the two bidentate ligands H L cis-coordinated into chains, whereas in 1·MeCN one of the sulfur atoms is
2
(
Figure 2). The fluorido co-ligands are coordinated cis to blocked by a BF4– anion. Geometric parameters for the in-
the oxido-bridge and in an unusual staggered way with re- ter- and intramolecular short contacts, hydrogen bonds and
spect to the Fe–O–Fe moiety. The F–Fe···Fe–F torsion π–π-stacking contacts are presented in Table 1.
angles are 97.3(1) and 100.1(2)° for 1·1.25MeOH and
The mononuclear compound 2·1.5H O crystallises in the
2
1
·MeCN, respectively. In the two other complexes with a monoclinic space group P 1/a with two complex cations,
2
III
III
[
Fe N F(μ-O)FN Fe ] entity published so far, namely two (disordered) tetrafluoroborate counter ions and three
4 4
2 2 2 2
L) L)
FFeIII(μ-O)FeIIIF(H ]2+, the complex cation
Figure 2. View of a) the molecular structure and b) the hydrogen-bonding motif of [(H
of 1·1.25MeOH. Hydrogen atoms, except for the amine groups, have been omitted for clarity.
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Table 1. Selected distances [Å] and angles [°] for [FeIII
·1.25MeOH[a] 1·MeCN[b]
(H
2
L)
F
2
(μ-O)](BF
)
2
·1.25MeOH (1·1.25MeOH) and 1·MeCN.
1·1.25MeOH
2
4
4
1
1·MeCN
Fe(1)–N(1)
Fe(1)–N(2)
Fe(1)–N(11)
Fe(1)–N(12)
Fe(1)–F(1)
Fe(1)–O(1)
Fe(2)–N(21)
Fe(2)–N(22)
Fe(2)–N(31)
Fe(2)–N(32)
Fe(2)–F(2)
Fe(2)–O(1)
2.170(3)
2.124(2)
2.289(2)
2.111(2)
1.893(2)
1.825(2)
2.179(3)
2.134(3)
2.267(3)
2.112(3)
1.918(2)
1.815(2)
2.170(6)
2.108(5)
2.290(5)
2.101(5)
1.900(4)
1.819(4)
2.180(6)
2.131(8)
2.283(8)
2.096(10)
1.911(4)
1.806(4)
N(1)–Fe(1)–N(2)
N(1)–Fe(1)–N(11)
N(1)–Fe(1)–N(12)
N(1)–Fe(1)–F(1)
N(1)–Fe(1)–O(1)
N(2)–Fe(1)–N(11)
N(2)–Fe(1)–N(12)
N(2)–Fe(1)–F(1)
N(2)–Fe(1)–O(1)
N(11)–Fe(1)–N(12)
N(11)–Fe(1)–F(1)
N(11)–Fe(1)–O(1)
N(12)–Fe(1)–F(1)
N(12)–Fe(1)–O(1)
F(1)–Fe(1)–O(1)
N(21)–Fe(2)–N(22)
N(21)–Fe(2)–N(31)
N(21)–Fe(2)–N(32)
N(21)–Fe(2)–F(2)
N(21)–Fe(2)–O(1)
N(22)–Fe(2)–N(31)
N(22)–Fe(2)–N(32)
N(22)–Fe(2)–F(2)
N(22)–Fe(2)–O(1)
N(31)–Fe(2)–N(32)
N(31)–Fe(2)–F(2)
N(31)–Fe(2)–O(1)
N(32)–Fe(2)–F(2)
N(32)–Fe(2)–O(1)
F(2)–Fe(2)–O(1)
Fe(1)–O(1)–Fe(2)
75.90(10)
82.31(9)
94.98(10)
162.10(9)
95.23(9)
86.87(9)
160.28(9)
88.65(9)
101.77(9)
74.47(9)
87.94(8)
170.22(9)
96.83(9)
96.39(9)
76.3(2)
82.31(18)
94.6(2)
163.18(19)
94.8(2)
87.22(19)
160.5(2)
89.6(2)
100.60(19)
74.33(18)
87.97(17)
170.80(18)
95.92(17)
97.31(19)
96.85(19)
76.1(3)
83.8(2)
92.2(3)
163.3(3)
96.7(2)
86.3(3)
159.1(3)
91.0(3)
100.7(2)
75.1(4)
84.76(19)
173.0(3)
96.5(3)
N(3)–H···F(1)
N(13)–H···O(1)
N(13)–H···F(2)
N(23)–H···O(1)
N(33)–H···O(1)
N(23)–H···F(2)
N(33)–H···F(1)
N(13)–H–F(2A)
N(3)–H···F(14)
N(33)–H···F(14B)
N(3)–H···O(50B)
N(33)–H···F(12)
S(1)···S(1C)
2.731
2.922
2.851
2.974
–
2.788
2.829
2.746
3.153
–
2.883
2.929
3.437(2)
3.475(2)
–
3.508
3.548
2.711
2.911
2.871
–
2.962
2.797
2.843
2.731
–
3.028
–
–
3.420(4)
–
3.15(1)
3.439
3.489
96.76(9)
75.92(11)
83.26(10)
93.61(11)
162.96(10)
95.59(9)
87.05(11)
160.36(11)
90.39(10)
100.23(10)
75.10(11)
86.00(9)
S(21)···S(21D)
S(21)···F(23D)
c(py1)···c(ta2)
c(py2)···c(ta1)
172.15(10)
96.36(10)
97.26(10)
96.81(8)
[
[
c]
c]
97.9(3)
96.22(19)
156.9(3)
157.72(13)
[
a] Symmetry operations used to generate equivalent atoms: A) –x + 1, –y + 2, –z + 1; B) –x + 2, –y + 2, –z; C) –x + 2, –y + 1, –z;
D) –x + 2, –y + 2, –z + 1. [b] Symmetry operations used to generate equivalent atoms: A) –x + 2, –y + 1, –z + 1; B) x + 1, y, z; C) –x
1, –y + 2, –z + 2; D) –x + 1, –y + 1, –z + 1. [c] c(py1): centroid{C(1)–C(2)–C(3)–C(4)–C(5)–N(1)}; c(py2): centroid{C(21)–C(22)–
+
C(23)–C(24)–C(25)–N(21)}; c(ta1): centroid{C(6)–C(7)–S(1)–C(8)–N(2)}; c(ta2): centroid{C(27)–C(28)–S(21)–C(28)–N(22)}.
water molecules in the asymmetric unit. The complex cat-
ions are isostructural and feature distorted octahedrally
N F coordinated ferric ions. The bidentate ligands are cis-
4
2
coordinated with the Nta donor atoms being trans to each
other and the Npy donor atoms being trans to the fluorido
ligands (Figure 3). Both fluorido co-ligands are involved in
intramolecular N–H···F hydrogen bonds and the amine
functions are hydrogen-bonded to tetrafluoroborate
counter ions and solvent molecules. Furthermore, intermo-
lecular hydrogen bonds between BF4– counter ions and sol-
vent molecules are present (see Table S1 in the Supporting
Information). Intermolecular π–π stacking between sym-
metry-generated molecules around Fe(1) lead to a chain-
like structure. A similar π–π-stacking motif is observed for
the second complex cation of the asymmetric unit (see
Table S1). A search for the FeN F fragment at the Cam-
4
2
bridge Crystallographic Data Centre[ yielded a total of
55]
–
six structures, none of them featuring cis-coordinated F
co-ligands or bidentate N2 ligands. The Fe –F bond
III
lengths in 2·1.5H O are in the range of 1.854(1)–1.873(1) Å,
2
comparable to those of 1·solvent (Table 2). The same ap-
Figure 3. View of the molecular structure of [FeIII(H
2 2
L) F
]+, the
III
III
2
plies to the Fe –N distances, the Fe –N
bonds
py
complex cation of 2·1.5H O. Only one complex cation of the two
2
[
2.151(2)–2.211(2) Å] being marginally longer than the
found in the asymmetric unit is shown. Hydrogen atoms, except for
the amine groups, have been omitted for clarity.
III
Fe –N bonds [2.087(2)–2.124(2) Å].
ta
Eur. J. Inorg. Chem. 0000, 0–0
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FULL PAPER
Table 2. Selected distances [Å] and angles [°] for [FeIII(H
L)
F
2
](BF
)·1.5H
O (2·1.5H
O) and [Co (H
II
L)
](ClO
)
2
2
2
4
2
2
2
3
4
2
·1.5MeOH·0.25H O
2
(3·1.5MeOH·0.25H O).
III [a]
II [b]
2
·1.5H
2
O (M = Fe
)
2
3·1.5MeOH·0.25H O (M = Co )
M(1)–N(1)
M(1)–N(2)
2.211(2)/2.191(2)
2.0866(19)/2.1237(19)
2.107(8) [2.17(3)]
2.127(7) [2.34(2)]
M(1)–N(11)
M(1)–(12)
2.188(2)/2.151(2)
2.0892(19)/2.0959(19)
2.145(2)
2.155(2)
Fe(1)–F(1)
Fe(1)–F(2)
1.8618(14)/1.8729(14)
1.8634(14)/1.8538(14)
–
–
Co(1)–N(21)
Co(1)–N(22)
–
–
2.122(2)
2.151(2)
N(1)–M(1)–N(2)
N(1)–Co(1)–N(1A)
N(2)–Co(1)–N(2A)
N(1)–M(1)–N(11)
N(1)–M(1)–N(12)
N(1)–Fe(1)–F(1)
N(1)–Fe(1)–F(2)
N(1)–Co(1)–N(21)
N(1)–Co(1)–N(22)
N(2)–M(1)–N(11)
N(2)–M(1)–N(12)
N(2)–Fe(1)–F(1)
N(2)–Fe(1)–F(2)
N(2)–Co(1)–N(21)
N(2)–Co(1)–N(22)
N(11)–M(1)–N(12)
N(11)–Fe(1)–F(1)
N(11)–Fe(1)–F(2)
75.71(8)/74.98(7)
–
–
84.39(8)/82.78(7)
92.29(7)/96.58(7)
166.71(7)/163.19(7)
88.83(7)/89.60(7)
78.7(3) [74.0(7)]
[71.3(7)]
[81.6(6)]
94.1(3) [86.6(9)]
171.2(3) [105.1(6)]
–
–
93.1(2) [71.3(7)]
91.2(3) [99.3(9)]
89.5(3) [90.3(10)];
98.3(2) [167.8(10)]
–
–
–
–
92.62(8)/95.99(8)
164.25(9)/169.55(9)
92.25(7)/89.94(7)
97.97(7)/95.98(7)
–
–
75.84(8)/76.57(7)
90.68(7)/91.64(7)
165.63(7)/163.64(7)
–
169.5(3) [90.7(6)]
96.0(3) [94.7(10)]
77.50(9)
–
–
N(11)–Co(1)–N(21)
N(11)–Co(1)–N(22)
N(12)–Fe(1)–F(1)
N(12)–Fe(1)–F(2)
N(12)–Co(1)–N(21)
N(12)–Co(1)–N(22)
F(1)–Fe(1)–F(2)
97.73(9)
173.06(9)
–
–
98.47(7)/97.52(7)
91.84(7)/90.02(7)
–
–
98.55(7)/99.48(7)
–
–
90.74(9)
97.38(9)
–
N(21)–Co(1)–N(22)
77.50(9)
[
a] The second value describes the second complex cation found in the asymmetric unit [Fe(2), C(21)–C(28), C(31)–C(38), N(21)–N(23),
N(31)–N(33), S(21), S(31), F(3) and F(4)]. [b] Minor part of the disordered ligand is given in brackets.
II
The 3:1-type cobalt(II) complex [Co (H L) ](ClO ) ·
2
3
4 2
1
.5MeOH·0.25H O (3·1.5MeOH·0.25H O) crystallises with
2 2
one complex cation, two perchlorate counter ions and par-
tially occupied solvent molecules adding up to 1.5MeOH
and 0.25H O in the asymmetric unit. The cobalt(II) ion lies
2
in a distorted octahedral N coordination sphere, coordi-
6
nated by three bidentate ligands H L. One of the ligands is
2
disordered such that about 78% of the fac isomer and 22%
of the mer isomer occupy the total site (Figure 4). The crys-
tallographic data for the above mentioned complexes are
presented in Table S3 in the Supporting Information, and
selected distances and angles are collected in Table 2.
The overall molecular structures of the 2:1-type com-
plexes 5–8 (Figure 5 and Figures S2–S4 in the Supporting
Information) are very alike and feature N distorted octa-
6
hedrally coordinated metal(II) ions. The bidentate ligands
are cis-coordinated with the Nta donor atoms being trans
to each other and the Npy donor atoms being trans to the
NCX (X = S, Se) co-ligands. In 5, the thiocyanato co-ligand
is disordered with the sulfur atom occupying two sites. The
major part, with a site occupancy of 0.80, has an N–C–S
II
2 3
L)
]2+, the
Figure 4. View of the molecular structure of [Co (H
complex cation of 3·1.5MeOH·0.25H O. Disorder in one of the
2
ligands is shown. The minor part [(A), occupation 22%] is drawn
with open bonds. Hydrogen atoms, except for the amine groups,
angle of 177.8(3)°, and the minor part has an angle of have been omitted for clarity.
Eur. J. Inorg. Chem. 0000, 0–0
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FULL PAPER
II
II
II
II
Table 3. Selected distances [Å] and angles [°] for [Fe (H
NCS) ] (8).
2
L)
2
(NCS)
2
] (5), [Fe (H
2
L)
2
(NCSe)
2
] (6), [Co (H
2
L)
2
(NCS)
2
] (7) and [Ni (H
2
L)
2
-
(
2
II [a]
II [b]
II [b]
II [a]
5
(M = Fe )
6 (M = Fe )
7 (M = Co )
8 (M = Ni )
M(1)–N(1)
M(1)–N(2)
M(1)–N(20)
2.196(3)
2.158(2)
2.141(3)
75.58(9)
85.67(11)
95.30(16)
96.66(10)
171.43(9)
91.83(10)
96.66(10)
168.67(16)
95.85(9)
171.43(9)
95.85(9)
94.64(15)
75.58(9)
85.67(11)
91.83(10)
2.190(4)
2.157(4)
2.155(4)
75.56(14)
171.39(15)
96.9(2)
98.14(15)
85.41(14)
95.93(14)
98.14(15)
170.7(2)
90.46(14)
85.41(14)
90.46(14)
93.5(2)
2.141(3)
2.121(3)
2.110(3)
2.097(2)
2.079(2)
2.083(2)
78.59(8)
174.28(7)
95.06(13)
96.83(8)
85.93(9)
95.70(8)
96.83(8)
173.30(12)
88.89(8)
85.93(9)
88.89(8)
93.64(12)
78.59(8)
174.28(7)
95.69(8)
N(1)–M(1)–N(2)
N(1)–M(1)–N(20)
N(1)–M(1)–N(1A)
N(1)–M(1)–N(2A)
N(1)–M(1)–N(20A)
N(2)–M(1)–N(20)
N(2)–M(1)–N(1A)
N(2)–M(1)–N(2A)
N(2)–M(1)–N(20A)
N(20)–M(1)–N(1A)
N(20)–M(1)–N(2A)
N(20)–M(1)–N(20A)
N(1A)–M(1)–N(2A)
N(1A)–M(1)–N(20A)
N(2A)–M(1)–N(20A)
77.06(11)
85.20(13)
95.36(19)
97.23(12)
172.80(11)
89.90(12)
97.23(12)
171.7(2)
95.74(11)
172.79(11)
95.74(11)
95.15(18)
77.06(11)
85.20(13)
89.90(12)
75.55(14)
171.39(15)
95.93(14)
[
a] Symmetry operation used to generate equivalent atoms: A) –x + 1, y, 0.5 – z. [b] Symmetry operation used to generate equivalent atoms:
A) –x, y, 0.5 – z.
Magnetic Properties, Mössbauer and UV/Vis Spectroscopy
III
III
The Mössbauer spectrum of [(H L) Fe F(μ-O)FFe -
2
2
(
H L) ](BF ) (1) recorded at 80 K shows a well-formed,
2 2 4 2
symmetrical doublet with an isomeric shift (IS) of δ =
0
=
.48 mms–1 and a small quadrupole splitting (QS) of ΔE
Q
–1
1.08 mms , as expected for a ferric complex in the high-
[
56,57]
spin (HS) state (Figure 6, top).
This was confirmed by
magnetic susceptibility measurements recorded in the range
2
1
0
95–2 K (Figure 6, bottom). The χ T value at 295 K is
M
3
–1
.08 cm mol K, that is higher than the spin-only value of
3
–1
.75 cm mol K expected for two independent iron(III)
sites in the low-spin (LS, S = 1/2) state, but significantly
3
–1
less than the spin-only value of 8.75 cm mol K expected
for two independent iron(III) sites in the HS (S = 5/2) state.
This suggests strong antiferromagnetic interactions within
III
III
the Fe –O–Fe moiety. On lowering the temperature the
magnetic susceptibility decreases until reaching a plane at
II
3
–1
Figure 5. View of the molecular structure of [Fe (H
(
2
L)
2
(NCS)
2
]
about 35 K and χ T = 0.07 cm mol K, which again indi-
M
5). The minor occupancy of the disordered NCS co-ligand is not
cates antiferromagnetic coupling and the presence of a
small amount of uncoupled paramagnetic impurities. In-
deed, analysis of the magnetic data by using the isotropic
Heisenberg–Dirac–van Vleck (HDVV) exchange Hamilto-
nian [Equation (1)], which includes an additional term for
shown. Hydrogen atoms, except for the amine groups, have been
omitted for clarity. Symmetry operation used to generate equivalent
atoms: A) –x + 1, y, –z + 0.5.
Zeeman splitting, leads to a good fit with values of g =
1
73.3(15)°. The M–N distances in 5–8 follow the expected
–1
2.02, J = –88 cm , paramagnetic impurities PI = 1.6% and
II
II
II
trend Fe Ͼ Co Ͼ Ni . Intermolecular S ···S and
SNCS···SNCS (5, 7, 8) or SeNCSe···SeNCSe (6) short contacts
are a common structural feature in the crystal packing of
ta
ta
temperature-independent
paramagnetism
(TIP)
=
–6
3
–1
33ϫ10
cm mol . The J value indicates strong antiferro-
magnetic interactions and lies in the range of experimental
II
5–8. Crystallographic data for [Fe (H L) (NCS) ] (5),
2
2
2
values for oxido-bridged dinuclear iron(III) complexes of J
II
II
[
Fe (H L) (NCSe) ] (6), [Co (H L) (NCS) ] (7) and
–1 [39,42,49]
2
2
2
2
2
2
= –80 to –130 cm .
II
[
Ni (H L) (NCS) ] (8) are presented in Table S4 in the Sup-
2
2
2
porting Information, selected distances and angles are listed
in Table 3 and S···S and Se···Se short contacts are listed in
Table S2.
(1)
Eur. J. Inorg. Chem. 0000, 0–0
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Figure 7. Top: Mössbauer spectrum of 2·1.5H
2
O recorded at 7, 80
Figure 6. Top: Mössbauer spectrum of 1 recorded at 80 K. The line
and 200 K. The lines represent simulations with Lorentzian singlets
see text). Bottom: χ T vs. T plot for 2·1.5H O. The solid line rep-
resents the best fit (see text).
represents fitting with a Lorentzian doublet (see text). Bottom: χ
m
T
(
M
2
vs. T plot for 1. The solid line represents the best fit (see text).
III
Mössbauer spectra of [Fe (H L) F ](BF )·1.5H O
2
2
2
4
2
(
2·1.5H O) were recorded at 7, 80 and 200 K and show
2
(
2)
broad singlets with isomeric shifts in the range of δ = 0.31–
0
ure 7, top).
–
1
.38 mms , typical values for iron(III) compounds (Fig-
[
56,57]
No quadrupole splitting is observed at any
temperature, probably due to slow paramagnetic relaxation.
UV/Vis spectra of [Fe(H L) (NCS) ] (5) and [Fe(H L) -
2 2 2 2 2
The presence of slow paramagnetic relaxation is addition- (NCSe) ] (6) were recorded in propylene carbonate. The
2
–1
–1
ally confirmed by the decreasing line-widths (Γ) at higher spectra show intense bands (ε = 812–1837 m cm ) in the
temperatures (Γ = 1.74 mms at 7 K, Γ = 1.72 mms at range of λ = 329–428 nm, which have been assigned to
0 K and Γ = 1.44 mms at 200 K) as the spin-lattice re- charge-transfer (CT) transitions. Furthermore, absorption
–
1
–1
–
1
8
laxation becomes faster. Therefore the iron(III) ion is be- bands at λ = 967 and 959 nm for 5 and 6, respectively,
lieved to be in the HS state (S = 5/2) at all temperatures. are observed in the spectra, which have been assigned to
5
5
This is confirmed by magnetic measurements recorded for
T Ǟ E transitions of HS iron(II). Owing to the proxi-
2g g
the same compound over the temperature range of 295–2 K mate O symmetry of these compounds, these transitions
h
–
1
–1
(
Figure 7, bottom). At 295 K, the χ T value for 2·1.5H O are very weak (ε = 14 and 17 m cm , respectively). The
is 4.37 cm mol K, which is close to the spin-only case for octahedral ligand-field splitting parameter for 5 and 6 was
S = 5/2 high-spin Fe (4.375 cm mol K). Data analysis calculated directly from these transitions to be 10Dq =
using a fitting procedure to the spin Hamiltonian for zero- 10300 and 10400 cm , respectively, typical values for
M 2
3
–1
III
3
–1
–1
[
58]
field splitting and Zeeman interaction [Equation (2)] and iron(II) in the HS state.
This was also verified for both
including a term for temperature-independent paramagne- compounds by magnetic measurements and Mössbauer
–1
tism (TIP) provided values of g = 2.0, |D| = 1.2 cm and spectroscopy, respectively (see Figure S5 and S6 in the Sup-
–
6
3
–1
TIP = 106ϫ10 cm mol .
porting Information).
Eur. J. Inorg. Chem. 0000, 0–0
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FULL PAPER
3
–1
The χ T value for 5 at 300 K (4.08 cm mol K) is reagent-grade. 2-Amino-4-(2-pyridyl)thiazole (H
2
L) was synthe-
Melting points were determined
M
sised as reported elsewhere.[
59,60]
higher than the spin-only value for a S = 2 ion
3.00 cm mol K), but not unexpected because g values for
iron(II) are commonly larger than the value of 2.0 for the
free electron (expected 4.07 cm mol K for g = 2.33). Upon
lowering the temperature, χ T at first remains constant un-
til 80 K and then drops increasingly rapidly to finally reach
.17 cm mol K at 1.9 K, which suggests a large zero-field
3
–1
by using a Thiele melting-point apparatus. Elemental analyses were
carried out by using a VarioMICRO or an Elementar Vario EL
(
–
1
analyser. IR spectra were recorded over the range 4000–400 cm
3
–1
by using a Nicolet Magna 760 FTIR spectrometer. Mass spectra
were recorded with a Thermo Exactive spectrometer equipped with
an Orbitrap-analysator. UV/Vis spectra were recorded over the
range 300–1000 nm by using an AnalytikJena Specord S 300 VIS
M
3
–1
1
splitting. Indeed, data analysis using a fitting procedure to spectrometer. Temperature-dependent magnetic susceptibilities
the spin Hamiltonian for axial (D) and rhombic (E) zero- were measured with a SQUID magnetometer (Quantum Design
field splitting and Zeeman interaction [Equation (3)] pro- MPMS XL-5) in the range of 295 (or 300) to 2.0 K at a magnetic
–
1
field of 0.5 T (or 0.1 T). Magnetic data were simulated by using the
julX program.[ The powdered samples were contained in a gel
bucket and fixed in a non-magnetic straw. Each raw data file of
the measured magnetic moment was corrected for the diamagnetic
contribution of the sample holder. The molar susceptibility data
were corrected for diamagnetic contributions. Mössbauer spectra
vides values of g = 2.33, |D| = 17.1 cm and |E/D| = 0.29.
61]
(
3)
5
7
The Mössbauer spectrum of 6 recorded at 8 K shows a were recorded with a Co source in a Rh matrix by using an alter-
doublet with an isomeric shift of δ = 1.15 mms and a nating constant acceleration Wissel Mössbauer spectrometer oper-
quite large quadrupole splitting of 1.84 mms , as expected ated in transmission mode and equipped with a Janis closed-cycle
–
1
–
1
for an iron(II) HS complex.[
56,57]
helium cryostat. Isomer shifts are given relative to iron metal at
ambient temperature. Simulation of the experimental data was per-
formed by using the Mfit program.[
62]
Conclusions
Single-crystal X-ray diffraction data were collected by using a
The molecule 2-amino-4-(2-pyridyl)thiazole (H L) has Bruker APEX-II CCD diffractometer with a microfused sealed
2
been used as a ligand for the first time to prepare iron(III), tube radiation source using graphite-monochromated Mo-K
α
radi-
ation (λ = 0.71073 Å). The structures were solved by direct methods
iron(II), cobalt(II), nickel(II) and copper(II) complexes.
using SHELXS-97[ and refined against F for all data by using
63]
2
The 3:1-type iron(II) complexes of H L that, in analogy to
2
[63]
full-matrix least-squares techniques with SHELXL-97. All non-
hydrogen atoms were refined anisotropically, except for one boron
atom in 1·1.25MeOH and 1·MeCN. All hydrogen atoms were
placed at calculated positions by using riding models. The disorder
in 5 was modelled for the NCS co-ligand with an occupation factor
of 0.80 for the major part. One ligand of the cobalt complex
such complexes of the 2-pyridyl-substituted thiazole-based
ligands IV and V (Figure 1), might exhibit SCO behaviour,
did not form. Instead, in the reaction of H L with Fe-
2
(
BF ) ·6H O, metal oxidation occurred along with fluoride
4 2 2
abstraction from the anion to form ferric fluorido com-
plexes. When working in MeCN or using MeOH and sol- 3·1.5MeOH·0.25H O was modelled with a disordered location with
2
vent evaporation, the oxido-bridged complex [(H L) - an occupation factor of 0.78 for the fac isomer and 0.22 for the
2
2
III
III
Fe F(μ-O)FFe (H L) ](BF ) (1) was formed, a rare ex- mer isomer. Geometrical restraints were used to make the minor
ample of a μ-oxido-bridged dinuclear ferric complex with
F co-ligands. Vapour diffusion of TBME into the MeOH
reaction solution generated the mononuclear complex
2
2
4 2
part “similar” to the major part.
–
CCDC-976063 (for 8), -976064 (for 1·1.25MeOH), -976065 (for
1·MeCN),
-976066
(for
2·1.25MeOH),
-976067
(for
III
[
Fe (H L) F ](BF ) (2), a rare example of an FeN F co- 3·1.5MeOH·0.25H O), -976068 (for 5), -976069 (for 6) and -976070
2 2 2 4 4 2
2
ordination sphere and the first such complex featuring cis- (for 7) contain the supplementary crystallographic data for this pa-
–
per. These data can be obtained free of charge from The Cambridge
Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_
request/cif.
coordinated F co-ligands or bidentate N ligands. Com-
2
plexes 1 and 2 contain iron(III) ions in the HS state, which,
in the case of 1, are strongly antiferromagnetically coupled
–
1
(
J = –88 cm ). Eventually a 3:1-type complex of H L, Synthesis of Complexes 1–8
2
II
namely [Co (H L) ](ClO ) (3), was obtained with Co-
2
3
4 2
FFeIII(μ-O)FeIIIF(H
[(H
2
L)
2
2
L)
2
4 2
](BF ) (1)
(
ClO ) ·6H O, whereas the use of Cu(ClO )·6H O resulted
4 2 2 4 2
II
in the formation of [Cu (H L) ](ClO ) (4) and employ- From MeOH: A solution of H
ment of Fe(ClO ) ·6H O or Ni(ClO ) ·6H O did not afford
any isolable product. Complexes of the type [M(H L) -
NCX) ] (5: M = Fe, X = S; 6: M = Fe, X = Se; 7: M =
Co, X = S; 8: M = Ni, X = S) were obtained by treating
H L with “M(NCX) ”. Spin-crossover properties were not
observed for the ferrous HS complexes 5 and 6.
2
L (142 mg, 800 μmol) in MeOH
2
2
4 2
(
10 mL) was added to a solution of Fe(BF ·6H O (135 mg,
4
)
2
2
4
2
2
4 2
2
400 μmol) in MeOH (5 mL). Slow evaporation of the solvent re-
2
2
sulted in the formation of a red crystalline solid, which was iden-
tified by X-ray diffraction as complex 1·1.25MeOH. Filtration,
(
2
washing with Et
2
O and drying in vacuo gave the bulk material of
L) ](BF ·2H O (1·2H O), yield 37%.
(H L)
HBF
O] – H
(1084.22): calcd. C
2
2
FFeIII(μ-O)FeIIIF(H
[
(H L)
2
2
2
2
4
)
2
2
2
+
MS (ESI, MeOH): m/z = 961.0096 {[Fe
2
2
4
F
2
+
O](BF
4
)} ,
6
95.9616 {[Fe
2
(H
2
L)
4
F
2
O](BF
4
)
–
H
L)
2
L
–
4
} , 437.0027
+
2+
[Fe
2
(H
78.0436 (H
2
L)
4
F
2
O]2 , 338.4808 {[Fe
2
(H
2
4
F
10Fe
2
2
L – HF} ,
Experimental Section
+
1
3
L ). C32
H
32
B
2
N
12
O
3
S
4
F
2
General: All chemicals and reagents were purchased from commer-
35.45, H 2.97, N 15.50; found C 35.44, H 2.82, N 15.43. Single
cial sources and used as received. All solvents used were laboratory
crystals of 1·1.25MeOH suitable for X-ray diffraction analysis were
Eur. J. Inorg. Chem. 0000, 0–0
8
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Job/Unit: I40041
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+
obtained in an analogous reaction but by applying a 3:1 ligand-to-
metal-ion ratio.
(HL)] . C16
H
14
N
6
O
8
S
2
Cl
2
Cu (616.89): calcd. C 31.15, H 2.29, N
13.62, S 10.39; found C 31.23, H 2.18, N 13.75, S 10.00. Crystals
obtained by this procedure unfortunately were not of sufficient
quality for single-crystal X-ray diffraction analysis.
From MeCN: Single crystals of 1·MeCN suitable for X-ray diffrac-
tion methods were obtained as follows. A solution of H
2
L (106 mg,
00 μmol) in MeCN (20 mL) was added to a solution of Fe(BF
O (67.5 mg, 200 μmol) in MeCN (10 mL). Slow evaporation of
II
6
6
4
)
2
·
[Fe (H
2
L)
2
(NCS)
2
] (5): Under a protective atmosphere of argon,
H
2
KSCN (38.9 mg, 400 μmol) and a pinch of ascorbic acid were
added to a solution of FeSO ·7H O (74.8 mg, 200 μmol) in MeOH
(15 mL). After stirring at room temp. for 5 min the reaction mix-
ture was filtered. A solution of H L (70.9 mg, 400 μmol) in MeOH
O (135 mg, 400 μmol) in MeCN (5 mL). Slow (20 mL) was added whilst stirring to the clear solution of
2
the solvent resulted in the formation of a red crystalline solid. Sol-
vent-free bulk material of 1 was obtained as follows. A solution of
4
2
H
2
L (213 mg, 1.20 mmol) in MeCN (30 mL) was added to a solu-
2
tion of Fe(BF ·6H
4
)
2
evaporation of TBME into the reaction mixture resulted in the for-
mation of a red crystalline solid of 1, which was isolated by fil-
“Fe(NCS)
2
” thus obtained. A brown precipitate formed. The mix-
II
ture was filtered and the solid residue of [Fe (H L) (NCS) ] (5)
2 2 2
tration, washed with Et
Ͼ220 °C. IR (diamond, ATR): ν˜ = 3397 (br), 3261 (br), 3125 (br),
604 (vs), 1566, 1517, 1468 (s), 1447, 1364, 1283, 1225, 1163, 1045
vs), 1014 (vs), 928, 845, 788 (s), 755 (s), 725, 686, 664, 637, 593,
2
O and dried in vacuo, yield 30%, m.p.
was washed with MeOH and dried in vacuo, yield 76%, m.p.
Ͼ220 °C. IR (diamond ATR): ν˜ = 3270 (br), 3177, 3101, 2026 (vs),
1600 (vs), 1564, 1517 (vs), 1465 (s), 1443 (s), 1356 (s), 1317, 1282,
1257, 1222, 1155, 1103, 1064, 1047, 1012, 923, 885, 841, 788, 749
1
(
–
1
–1
5
{
20, 443, 423, 411 cm . MS (ESI, MeOH): m/z = 961.0081
(vs), 720, 685, 665, 637, 607, 589, 487, 465, 411 cm . UV/Vis (PC):
+
–1
–1
[Fe
2
(H
2
+
L)
4
F
2
O](BF
4
)} , 695.9612 {[Fe
2
(H
2
L)
4
F
2
O](BF
4
) – H
L) O] –
L – HF} , 178.0433
(1048.19): calcd. C 36.67, H 2.69,
2
L –
λ
max (ε) = 366 (1628), 424 (1837), 428 (1837), 967 (14 m cm ) nm.
2+
HBF
4
+
} , 437.0021 [Fe
2
(H
2
L)
4
F
2
O] , 426.9991 {[Fe
2
(H
2
4
F
2
C H N S Fe (526.45): calcd. C 41.07, H 2.68, N 21.28, S 24.36;
18 14 8 4
HF}2 , 338.4808 {[Fe
(H L) F O] – H
2+
found C 40.46, H 2.46, N 21.08, S 24.48. Single crystals suitable
for X-ray diffraction analysis were obtained by this method, but by
allowing the mixture to stand for 10 d without stirring.
2
2
4 2 2
+
(H
3
L ). C32
H
28
B
2
N12OS
4
F
10Fe
2
N 16.01; found C 36.77, H 2.99, N 16.24.
II
FeIII(H
[Fe (H L) (NCSe) ] (6): Under a protective atmosphere of argon,
[
2
L) ](BF ) (2): A solution of H
2
F
2
4
2
L (142 mg, 800 μmol) in
2
·6H O
2
2
2
a solution of FeSO
00 μmol) and a pinch of ascorbic acid in MeOH (5 mL) was
4 2
·7H O (74.8 mg, 200 μmol), KNCSe (57.6 mg,
MeOH (10 mL) was added to a solution of Fe(BF
4
)
2
4
(135 mg, 400 μmol) in MeOH (5 mL). Vapour diffusion of TBME
stirred for 5 min at room temp. The solvent was removed under
reduced pressure and the residue digested in MeCN (5 mL). The
resulting suspension was filtered to obtain a clear MeCN solution
into the dark-red reaction solution resulted in the formation of a
red crystalline solid, which was identified by X-ray diffraction as
complex 2·1.5MeOH. Filtration, washing with Et
2
O and drying in
](BF )·1.5H
O), yield 63%, m.p. Ͼ220 °C. IR (diamond ATR): ν˜ =
594, 3423 (br), 3274 (br), 3132, 1608 (vs), 1567, 1514, 1470 (s),
449, 1372, 1285, 1228, 1036 (vs), 1017 (vs), 930, 838, 791, 758 (s),
III
2 2
of “Fe(NCSe) ”. A solution of H L (70.9 mg, 400 μmol) in MeCN
vacuo gave the bulk material of [Fe (H
2·1.5H
2
L)
2
F
2
4
2
O
(
10 mL) was added whilst stirring. A brown precipitate of
(
2
II
[Fe (H
2
L)
2
(NCSe)
2
] (6) formed, which was collected by filtration,
3
1
7
washed with Et
2
O and dried in vacuo, yield 45%, m.p. Ͼ220 °C.
–1
IR (diamond ATR): ν˜ = 3270 (br), 3069 (br), 2038 (vs), 1598 (s),
31, 688, 665, 644, 586, 502 (vs), 467, 425, 412 cm . MS (ESI,
+
1513 (vs), 1453, 1351 (s), 1312, 1216, 1149, 1102, 1045, 921, 840,
MeOH) m/z = 460.0232 [Fe(H
2
L)
17BN
2
FCH
3
O] , 448.0032 [Fe(H
Fe (544.10): calcd. C
4.19, H 3.05, N 14.95, S 11.41; found C 34.60, H 3.11, N 14.94,
2 2
L) -
–
1
+
+
787, 744, 714 (s), 672, 588, 457, 410 cm . UV/Vis (PC): λ
max
(ε)
Fe
F
3
2
] , 178.0433 [H
3
L] . C16
H
6
O
1.5
F
6
S
2
–
1
–1
=
329 (812), 360 (1457), 959 (17 m cm ) nm. C18
H
14
N
8
S
2
Se
2
(
620.25): calcd. C 34.86, H 2.28, N 18.07, S 10.24; found C 34.89,
S 11.70.
–
1
H 2.15, N 18.27, S 10.30. Mössbauer at 8 K: IS = 1.15 mms , QS
1
Caution! While no problems were encountered in the course of this
–1
.84 mms . Single crystals of 6 suitable for X-ray diffraction
–
work, ClO
4
salts are potentially explosive and should be handled
analysis were obtained by this method, but from MeOH solution
and allowing the mother liquor to stand for 8 d without stirring.
with appropriate care.
II
II
[
2
(
3
Co (H
2
L)
3
](ClO
4
)
2
(3): A solution of Co(ClO
4
)
2
·6H
2
O (73.2 mg, [Co (H L) (NCS) ] (7): A mixture of CoSO ·7H O (112 mg,
2
2
2
4
2
00 μmol) in MeOH (5 mL) was added to a solution of H
106 mg, 600 μmol) in MeOH (10 mL). After 20 d in air
·1.5MeOH·0.25H O was isolated in the form of an orange crystal-
line material suitable for X-ray diffraction analysis. Filtration and
2
L
400 μmol) and KSCN (78.0 mg, 800 μmol) in MeOH (15 mL) was
stirred for 5 min at room temp. The reaction mixture was filtered
to obtain a clear solution of “Co(NCS) ” in MeOH and a solution
2
2
of H L (142 mg, 800 μmol) in MeOH (20 mL) was added. The mix-
2
II
drying in vacuo gave the bulk material [Co (H
2
L)
3
](ClO
4
)
2
·H
2
O
ture was allowed to stand at room temp. without stirring. After
10 d a yellow crystalline solid of [Co (H L) (NCS) ] (7) was col-
lected by filtration, washed with MeOH and dried in vacuo, yield
43%, m.p. Ͼ220 °C. IR (diamond ATR): ν˜ = 3272 (br), 3074, 2023
(brs), 1604 (s), 1558, 1524 (vs), 1465 (s), 1442 (s), 1356 (s), 1287,
1257, 1221, 1104 (s), 1065, 1045 (vs), 1014, 923, 885, 838, 788, 748
s), 722, 683, 665, 618, 589, 489, 463, 415, 402 cm . C18
529.54): calcd. C 40.83, H 2.66, N 21.16; found C 40.60, H 3.00,
N 20.87. Single crystals of 7 suitable for X-ray diffraction analysis
were obtained by this method.
II
(
3·H
2
O), yield 50%, m.p. Ͼ220 °C. IR (diamond ATR): ν˜ = 3443,
2
2
2
3
9
4
1
331, 3116, 1605 (s), 1517, 1468, 1445, 1351, 1284, 1074 (vs), 1018,
19, 846, 789, 753 (s), 713, 686, 666, 644, 620 (vs), 481, 466, 451,
29 cm . C24H N O S Cl Co (807.52): calcd. C 35.70, H 2.87, N
23 9 9 3 2
5.61, S 11.91; found C 35.29, H 2.47, N 15.41, S 11.61.
–
1
–
1
(
14 8 4
H N S Co
II
[
2
(
Cu (H
2
L)
2
](ClO
4
)
2
(4): A solution of Cu(ClO
4
)
2
·6H
2
O (74.1 mg,
(
2
00 μmol) in MeOH (5 mL) was added to a solution of H L
70.9 mg, 400 μmol) in MeOH (10 mL). The reaction mixture was
allowed to stand at room temp. After 1 d a dark crystalline solid
of [Cu (H
II
II
2
L)
2
](ClO
4
)
2
(4) had formed, which was collected by fil-
[Ni (H
2
L)
2
(NCS)
2
] (8): A mixture of NiSO
4
·6H
2
O (71.2 mg,
tration, washed with MeOH and dried in vacuo, yield 60%, m.p.
200 μmol) and KSCN (38.9 mg, 400 μmol) in MeOH (15 mL) was
Ͼ220 °C. IR (diamond ATR): ν˜ = 3344, 2160 (s), 2134, 1623 (s),
stirred for 5 min at room temp. The reaction mixture was filtered
1
4
604 (s), 1526 (s), 1467, 1047 (vs), 1019 (s), 795, 761, 716, 621 (vs), to obtain a clear MeOH solution of “Ni(NCS)
2
” and a solution of
–1
80 (s), 420 (s) cm . MS (ESI, MeOH): m/z = 208.5001 [Cu-
2
H L (38.9 mg, 400 μmol) in MeOH (20 mL) was added. The mix-
2+
+
(H
2
L)
2
]
,
515.9493 {[Cu(H
2
L)
2
]ClO
4
} , 415.9929 [Cu(H
2
L)-
ture was allowed to stand at room temp. without stirring. After
9 © 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 0000, 0–0

Job/Unit: I40041
/KAP1
Date: 22-05-14 11:22:15
Pages: 12
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FULL PAPER
II
1
2 2 2
2 d a blue crystalline solid of [Ni (H L) (NCS)
] (8) was collected [22] V. Niel, A. B. Gaspar, M. C. Muñoz, B. Abarca, R. Ballesteros,
J. A. Real, Inorg. Chem. 2003, 42, 4782–4788.
by filtration, washed with MeOH and dried in vacuo, yield 35%,
m.p. Ͼ220 °C. IR (diamond ATR): ν˜ = 3265 (br), 3074, 2037 (brs),
602 (s), 1562, 1522 (vs), 1465, 1442 (s), 1358 (vs), 1317, 1282,
257, 1221, 1153, 1105, 1067, 1047, 1014, 881, 837, 786, 748 (vs),
14 8 4
18 (s), 684, 664, 639, 589, 489, 466, 442, 414 cm . C18H N S Ni
529.29): calcd. C 40.85, H 2.67, N 21.17, S 24.23; found C 40.50,
H 2.27, N 20.98, S 23.78. Single crystals of 8 suitable for X-ray
diffraction analysis were obtained by this method.
[
[
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(
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1
Supporting Information (see footnote on the first page of this arti-
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, Mössbauer spectrum of 6, tables with short contacts in 2·1.5H O
and 5–8 and crystallographic data for the structures described in
[
[
[
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M
T vs. T plot of
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Acknowledgments
[32] L. Farkas, E. Kasztreiner, F. Andrasi, J. Borsi, I. Elekes, I. Pol-
This work was supported by the European Social Fund and the
Ministry of Science, Research and the Arts, Baden-Württemberg,
Germany within the Margarete-von-Wrangell-Programm and by
the Deutsche Forschungsgemeinschaft (DFG). Financial support
from the Fonds der Chemischen Industrie (FCI) is also gratefully
acknowledged. Prof. Annie K. Powell and Prof. Franc Meyer are
thanked for the allocation of technical equipment. The authors are
indebted to Maximilian Schmucker for technical assistance. J. K.
thanks Prof. Ingo Krossing and Prof. Harald Hillebrecht for their
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FULL PAPER
[
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Published Online: ᭿
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FULL PAPER
2-Pyridylazole Ligands
T. Huxel, S. Leone, Y. Lan, S. Demeshko,
J. Klingele* ..................................... 1–12
4 2 2
On treatment with Fe(BF ) ·6H O, the 2-
amino-4-(2-pyridyl)thiazole ligand forms
rare examples of either an oxido-bridged
–
2-Amino-4-(2-pyridyl)thiazole as Chelating
ferric complex with F co-ligands or a
Ligand: A Dinuclear Oxido-Bridged Ferric
Complex and Mononuclear 3d Metal
Complexes
mononuclear difluorido ferric complex
with FeF N coordination, depending on
2 4
the reaction conditions.
Keywords: N ligands / Chelates / Nitrogen
heterocycles / Iron / Fluorides
Eur. J. Inorg. Chem. 0000, 0–0
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© 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim