Cobalt(II), nickel(II) and copper(II) compounds derived from template reactions of enantiomerically pure 2-amino-thiazoles

Article abstract of DOI:10.1016/j.poly.2009.12.003

Herein we report the syntheses and structural analyses of three coordination compounds Co(L)₂ (3), Ni(L)₂, (4) and Cu(L)₂ (5) (L = bis[(4R,5R)-4-methyl-5-phenyl-4,5-dihydro-thiazol-2-yl]-amine) prepared by template reactions from the optically active ligand (4R,5R)-4-methyl-5-phenyl-4,5-dihydro-thiazol-2-yl-amine (1) and CoCl₂·6H₂O, NiBr₂·3H₂O or Cu(OAc)₂·H₂O The template reactions involve the condensation of two molecules of thiazol-2-yl-amine and elimination of one NH₃. The resulting bidentate ligand coordinates to the metal ion through the imine nitrogen atoms forming a six-membered ring, presenting an electronic delocalization which averages the four M-N bond lengths. The distorted tetrahedral geometry of the metal atoms gives place to complex electronic spectra for compounds 3-5. A mixed ionic compound (6) formed by three cations (4S,5S)-3,4-dimethyl-5-phenyl-thiazolidin-2-ylidene ammonium, one dianion tris-(thiocyano)bromide cobaltate and one bromide, obtained from reaction of (4S,5S)-3,4-dimethyl-5-phenyl-thiazolidin-2-ylidene ammonium thiocyanate (2) and CoBr₂ is also described. Compounds 3-6 were characterized in the solid state by UV-Vis-NIR and IR spectroscopy, mass spectrometry and X-ray diffraction analyses. Metal···H-C, S···H-C interactions were observed in 3-6, whereas in 6, also Br···H-N, Br···H-C and Br···S, S···S short contacts were found.

Full text of DOI:10.1016/j.poly.2009.12.003

Polyhedron 29 (2010) 1007–1014
Contents lists available at ScienceDirect
Polyhedron
journal homepage: www.elsevier.com/locate/poly
Cobalt(II), nickel(II) and copper(II) compounds derived from template reactions
of enantiomerically pure 2-amino-thiazoles
a
b
b
b
Raúl Ramírez-Trejo , Angelina Flores-Parra , José Adrián Peña-Hueso , Edgar Mijangos ,
b,
a,
*
*
Rosalinda Contreras , Norah Barba-Behrens
a
Departamento de Química Inorgánica, Facultad de Química, Universidad Nacional Autónoma de México, C.U., Coyoacán, México, D.F. 04510, Mexico
Departamento de Química, Centro de Investigación y de Estudios Avanzados, A.P. 14-740, México, D.F. 07000, Mexico
b
a r t i c l e i n f o
a b s t r a c t
Article history:
Herein we report the syntheses and structural analyses of three coordination compounds Co(L)2 (3),
Received 5 September 2009
Accepted 2 December 2009
Available online 5 December 2009
Ni(L)
by template reactions from the optically active ligand (4R,5R)-4-methyl-5-phenyl-4,5-dihydro-thiazol-
-yl-amine (1) and CoCl O, NiBr ꢀ3H O or Cu(OAc) ꢀH O The template reactions involve the conden-
ꢀ6H
sation of two molecules of thiazol-2-yl-amine and elimination of one NH . The resulting bidentate ligand
2 2
, (4) and Cu(L) (5) (L = bis[(4R,5R)-4-methyl-5-phenyl-4,5-dihydro-thiazol-2-yl]-amine) prepared
2
2
2
2
2
2
2
3
Keywords:
coordinates to the metal ion through the imine nitrogen atoms forming a six-membered ring, presenting
an electronic delocalization which averages the four M–N bond lengths. The distorted tetrahedral geom-
etry of the metal atoms gives place to complex electronic spectra for compounds 3–5. A mixed ionic com-
pound (6) formed by three cations (4S,5S)-3,4-dimethyl-5-phenyl-thiazolidin-2-ylidene ammonium, one
dianion tris-(thiocyano)bromide cobaltate and one bromide, obtained from reaction of (4S,5S)-3,4-
Transition metal bis(tricyclic) compounds
Bis[4,5-dihydrothiazole-2-yl]amine
Template reactions
2
dimethyl-5-phenyl-thiazolidin-2-ylidene ammonium thiocyanate (2) and CoBr is also described. Com-
pounds 3–6 were characterized in the solid state by UV–Vis–NIR and IR spectroscopy, mass spectrometry
and X-ray diffraction analyses. MetalꢀꢀꢀH–C, SꢀꢀꢀH–C interactions were observed in 3–6, whereas in 6, also
BrꢀꢀꢀH–N, BrꢀꢀꢀH–C and BrꢀꢀꢀS, SꢀꢀꢀS short contacts were found.
Ó 2009 Elsevier Ltd. All rights reserved.
1
. Introduction
Thiazoles have shown fungicide [1] and promising activity for
knowledge, bis[4,5-dihydrothiazol-2-yl]amines have not been re-
ported before, there are only two examples of their unsaturated
analogues. One of them is the synthesis of bis[thiazol-2-yl]amine
by a traditional method [17] and the other one is a patent [18]
where compounds bearing three bis[thiazol-2-yl]amines coordi-
nated to Co(III) are used as optical recording materials. The metal-
lic template reactions to give bis(azolyl)-amines, as far as we know,
have not been described before.
The synthesized compounds are optically active and therefore
they could have possible application in asymmetric synthesis, as
it has been found for zinc(II) and copper(II) coordination com-
pounds derived from bis-oxazolidines, which are remarkable
enantioselective catalysts on Friedel-Crafts or Michael reactions
[19–23].
the treatment of Alzheimer disease [2], their derivatives have an
important role as nitric oxide synthase inhibitors [3–6] and have
been used in the evaluation of possible glycosidase inhibitors
[
7–9]. They are also found in natural antibiotics, as is the case of
2+
2+
3+
micacocidin, which was isolated with Zn , Cu or Fe , where
the chelating groups are the imino nitrogens of the thiazole rings
[
10–13]. Thiazoline derivatives have been applied as ionic liquids,
in chiral recognition and asymmetric synthesis [14,15]. Rhodium
coordination compounds with chiral thiazolidines have been used
as catalysts in asymmetric hydrosilation [16].
Herein we report the reactions of the 2-amino-thiazoles
[
(4R,5R)-4-methyl-5-phenyl-4,5-dihydro-thiazol-2-yl-amine
(1)
Compounds 1 and 2 were obtained in previous works [24–28],
Scheme 1. They are prepared from the optically active ethanol-
amine, through the synthesis of the chloro derivatives, which af-
ford the thiazolidine by reaction with NaCN. The reaction to
obtain compound 1 gives a mixture of two diasteromers the cis
and trans in 85–15 ratio. From crystallization in methanol, the
trans isomer, is obtained pure. Compound 1 has an imine and a sul-
fur atom as possible coordination sites, whereas 2 is an ionic com-
pound, where the cation has only a sulfur atom as a basic site. Both
and (4S,5S)-3,4-dimethyl-5-phenyl-thiazolidin-2-ylidene ammo-
nium thiocyanate (2)] with transition metal ions. We found that
the metal atom induces the template condensation reaction of
two 4,5-dihydro-thiazole molecules to give the bis[4,5-dihy-
drothiazol-2-yl]amine coordinated to the metal atom. To our
*
Corresponding authors.
E-mail address: norah@servidor.unam.mx (N. Barba-Behrens).
0
277-5387/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2009.12.003

1
008
R. Ramírez-Trejo et al. / Polyhedron 29 (2010) 1007–1014
O
S
2
2
eq.
OH
Cl
+
1
) 2 eq. NaSCN
Cl
Cl
Cl
S
N
H
H
ethanol
N
-
H C
NH2
H C
NH Cl
3
3
3
2) NaOH
H C
3
1
+
SCN-
O
S
eq.
OH
Cl
Cl
2 eq. NaSCN
-
ethanol
S
H
N
+
H C
NH
CH3
H C
NHCl
N
CH3
H
3
3
2
H C
3
CH3
2
Scheme 1. Synthesis of compounds 1 and 2.
heterocycles contain labile amine and iminium protons which can
be substituted by heteroatoms generating more complex ligands
2
SOCl (59 g, 36 mL), after maintaining the reaction mixture at 0°
for 4 h, acetone was added (100 mL). (4R,5R)-(2-Chloro-1-
methyl-2-phenyl-ethyl)-amine hydrochloride (yield 72%) was
recovered as a white solid (24.59 g, 119 mmol). It was washed
three times with acetone and then dissolved in ethanol. To this
solution, NaSCN (19.29 g, 238 mmol) was added and the reaction
mixture maintained under reflux for 4 h. The resultant NaCl was
filtered off and the yellow solution concentrated to the half of its
original volume under vacuum. Then NaOH (4.8 g, 119 mmol)
was added. The reaction product is a 85:15 mixture of the cis:trans
isomers, from this mixture the trans isomer (4R,5R) was isolated by
[
29,30]. Compounds 1 and 2 were used in the synthesis of novel
transition metal compounds 3–6, which were characterized in
the solid state by UV–Vis–NIR reflectance and IR spectroscopy,
mass spectrometry and X-ray diffraction analyses, Schemes 2
and 3.
2
. Experimental
2.1. Physical measurements
crystallization in methanol as colorless needles (1.31 g, 4.1%). Mp.
1
1
51–153 °C with dec. NMR (methanol-d
3
) H d: H
5
4.52 (d 6.7 Hz),
FT IR spectra were recorded with a (Perkin–Elmer 1600) spec-
13
ꢁ1
4 3
H 4.25 (m), CH 1.32 (d 6.5 Hz), NH 4.99, aromatics 7.33 (m). C d:
trophotometer using KBr pellets (4000–400 cm ). The UV–Vis–
ꢁ1
169.7 (C@N), 141.8 (C ), 130.2 (C ), 129.2 (C ), 129.4 (C ), 71.4 (C–
NIR spectra (diffuse reflectance, 40 000–4000 cm ) were recorded
on a Cary-5E (Varian) spectrophotometer. High resolution mass
spectra were obtained by LC/MSD TOF on Agilent Technologies
instrument with APCI as ionization source. The fast atom bombard-
ment mass spectra (FAB+ mass) were performed with a JEOL
SX102A instrument with an inverted geometry, in a matrix of 3-
nitrobenzyl alcohol, in the 0–2200 m/z range. NMR spectra were
recorded on a JEOL GSX-270. Elemental analyses were carried out
with a Fisons EA 1180 analyzer.
i
o
m
p
ꢁ
1
Ph), 60.8 (C–Me), 20.05 (CH
3
). IR (KBr):
m
max [cm ] 3449 (N–H),
= ꢁ155.
3
352 (N–H), 1573 (C@N), 1452 (C–N), 698 (C–S). ½ꢂ
a
CDCl
3
+
MS: m/z 192 (95) [M] , 70(100), 177(93), 69(80), 57(69), 149(67).
Anal. Calc. for C10 S: C, 62.47; H, 6.29; N, 14.57; S, 16.68.
12 2
H N
Found: C, 62.11; H, 6.32; N, 14.89; S, 17.34%.
2.3.2. (4S,5S)-3,4-Dimethyl-5-phenyl-thiazolidin-2-ylidene
ammonium thiocyanate, 2
2.2. Materials
An ethanolic solution (100 mL) of (1S,2S)-(2-chloro-1-methyl-
2
-phenyl-ethyl)-methylamine hydrochloride [5.05 g, 23 mmol,
The inorganic salts CoCl
O and methanol (J.T. Baker) were used without further purifi-
cation.
2
ꢀ6H
2
O, CoBr
2
, NiBr
2
ꢀ3H
2
O, Cu(OAc)
2
ꢀ
prepared from (1R,2S)-N-methyl-2-methyl-1-phenyl-ethanol-
amine] and NaSCN (3.72, 45.9 mmol) was refluxed for 8 h, then
the precipitate was filtered and dissolved in ethanol. The solution
H
2
was concentrated, and crystals were obtained (3.22 g, 53%). Mp.
1
2
2
.3. Synthesis
165–168 °C. NMR (methanol-d
m), CH 1.39 (d 6.3 Hz), N–CH
32.80 (N–Me), C 69.77 C
128.66, C 167.47. IR (KBr):
H), 1600 (C@N), 1493 (C–N), 1452 (C–N), 699 (C–S).
3
)
H d: H
5
4.92 (d 4.9 Hz), H
4
4.41
1
3
(
3
3
3.22 (s), aromatic 7.43 (m). C d:
16.64 C 138.29, C 129.07,
max [cm ] 3060 (N–H), 3029 (N–
.3.1. (4R,5R)-4-Methyl-5-phenyl-4,5-dihydro-thiazol-2-yl-amine, 1
To obtain compound 1, (1S,2R)-2-methyl-1-phenyl-ethanol-
amine (25 g, 165 mmol) was reacted with three equivalents of
4
5
53.39 CH
3
i
o
ꢁ
1
C
p
2
m
N
S
S
N
N
S
N
H
H
1) NaOH
H C
M
CH3
N
3
H C
3
CH3
2
) MX2
M
H C
3
2+
N N
3
4
5
Co
2+
Ni
Cu
S
-
-
-
N S
2+
1
X = Cl , Br or AcO
.
.
Scheme 2. Synthesis of coordination compounds 3–5.

R. Ramírez-Trejo et al. / Polyhedron 29 (2010) 1007–1014
1009
_
+
+
SCN
2-
Br
S
H
H
CoBr2
S
H
H
3
+
Co
N
3
N
SCN
NCS
+
Br
methanol
N
CH3
N
CH3
SCN
H C
H C
3
3
2
6
Scheme 3. Synthesis of the mixed ionic compound 6.
max [cm 1]: 1517 (C@N), 1467 (C–
Ni + H+ 791, Mass + TOF calc.
Ni + H 791.1629, found: 791.1633). Anal. Calc. for
Niꢀ4H O: C, 55.62; H, 5.60; N, 9.73; S, 14.85. Found: C,
55.92; H, 5.40; N, 9.22; S, 14.05%.
ꢁ
2
.3.3. Cobalt(II) compound 3, general procedure
Compound 1 (96 mg, 0.5 mmol) was dissolved in methanol
55%). Dec. at 145 °C. I.R. (KBr)
40 6 4
N), 698 (C–S). (Mass FAB C40H N S
for C40H N S
40 6 4
m
+
(
50 mL) and a NaOH solution (1.1 ml, 0.25 M) was added. The mix-
ture was stirred for 15 min followed by the addition of CoCl
ꢀ6H
30 mg, 0.125 mmol). The reaction mixture was set aside for
2
2
O
C H
40 40
N
S
6 4
2
(
4
days. The coral colored solid was filtered off and redissolved in
methanol. After slow evaporation of the solvent, red crystals of 3,
2
.3.5. Copper(II) compound 5
Following the same procedure as for compound 3. Compound 1
suitable for diffraction analyses were obtained (49 mg, 48%). Dec.
ꢁ
1
at 145 °C. IR (KBr),
mmax [cm ] 1509 (C@N), 1473 (C–N), 698 (C–
(
0
96 mg, 0.5 mmol), methanol (50 mL), a NaOH solution (1.1 mL,
.25 M) and Cu(OAc) O (30 mg, 0.125 mmol) were added. Crys-
+
S). Mass FAB C H N S Co + H 792. Mass + TOF calc. for
40 40 6 4
2
ꢀH
2
C
C
6
40
H
H
40
N
N
6
S
S
4
Co + H+ 792.1607, found: 792.1596. Anal. Calc. for
tallization from methanol afforded dark green needles of com-
pound 5 (20 mg, 20%). IR. (KBr)
Co: C, 60.66; H, 5.09; N, 10.61; S, 16.19. Found: C,
ꢁ1
40
40
6
4
m
max [cm ]: 1524 (C@N), 1475
0.91; H, 5.32; N, 10.29; S, 16.35%.
Cu + H+
(
C–N), 698 (C–S). Mass + TOF calc. for
C
40
40
H N
S
6 4
7
5
1
96.1571, found: 796.1574. Anal. Calc. for C40
7.70; H, 5.33; N, 10.09. S, 15.40. Found: C, 57.27; H, 4.96; N,
0.12; S, 14.75%.
H
40
N
6
S
4
Cuꢀ2H
2
O: C,
2
.3.4. Nickel(II) compound 4
Following the same procedure for compound 3. To a methanolic
solution (50 mL) of compound 1 (96 mg, 0.5 mmol), a NaOH solu-
tion (1.1 mL, 0.25 M) and NiBr O (33 mg, 0.125 mmol) were
added. A light green solid was filtered and dissolved in acetone,
crystallization from acetone afforded dark green crystals (54 mg,
2
ꢀ3H
2
2.3.6. Cobalt(II) compound 6
Compound 2 (100 mg, 0.38 mmol) was dissolved in methanol
2
(50 mL), followed by the addition of anhydrous CoBr (83 mg,
Table 1
Crystal data, data collection and refinement details.
Chemical formula
Formula weight (g molꢁ1)
Crystal size (mm)
Crystal color
Crystal system
Space group
a (Å)
C
40
H
40
N
6
S
4
Co(3)
C
40
H
40
N
6
S
4
Ni(4)
C
40
H
40
N
6
S
4
Cu(5)
14 15 5 4 2
C H N S Br Co(6)
338.31
791.97
791.77
796.59
0.38 ꢃ0.25 ꢃ0.15
0.45 ꢃ0.1 ꢃ0.02
0.38 ꢃ0.2 ꢃ0.1
0.32 ꢃ0.2 ꢃ0.2
dark pink
dark green
dark green
blue
monoclinic
P2
monoclinic
P2
monoclinic
P2
trigonal
P6
3
15.4208(2)
15.4208(2)
10.9354(2)
90.00
1
1
1
9.1170(1)
12.7538(2)
17.2515(3)
90.00
97.435(1)
90.00
1989.37(5)
2
1.322
9.0424(4)
12.6861(7)
17.2486(9)
90.00
97.317(4)
90.00
1962.52(17)
2
1.340
9.15790(10)
12.6488(2)
17.2716(3)
90.00
98.2336(7)
90.00
1980.06(5)
2
1.336
b (Å)
c (Å)
a
(°)
b (°)
(°)
90.00
c
120.00
2254.49
6
1.495
2.468
3
V (Å )
Z
D
l
3
calc (g/cm )
ꢁ
1
(mm
)
0.678
0.744
0.799
F(0 0 0)
826
828
830
1034
T (K)
293
293
293
293
h
h
min
max
1.19
30.50
3.07
29.46
1.19
30.55
3.05
30.49
Index range
ꢁ12 6 h 6 12
ꢁ11 6 h 6 11
ꢁ17 6 k 6 14
ꢁ22 6 l 6 21
10 516
ꢁ10 6 h 6 12
ꢁ18 6 k 6 18
ꢁ24 6 l 6 24
36 255
24 472
11 025 [I > 2.5
581
0.0281
0.032
1.03
ꢁ21 6 h 6 21
ꢁ21 6 k 6 21
ꢁ15 6 l 6 15
46 305
4417
ꢁ
18 6 k 6 17
23 6 l 6 24
ꢁ
Reflections measured
Independent reflections
Reflections
Number of parameters
R
26 236
10 854
7215 [I > 3.0
581
6799
r
(I)]
4983 [I > 2.5
r
(I)]
r(I)]
3139 [I > 2.5
179
r(I)]
491
0.037
0.034
1.06
0.031
0.030
0.95
0.048
0.047
0.98
R
S
w
Maximum
D
/
r
0.001
0.39
0.000
0.33
0.001
0.44
0.000
0.47
3
D
D
q
q
Maximum (e Å )
minimum (e Å )
3
ꢁ0.50
ꢁ0.38
ꢁ0.54
ꢁ0.47
Flack parameter
0.00(1)
0.00(1)
0.00(1)
0.22(2)
h
i
¼P
jFo ꢁhF ij= F ; R
P
¼P
jjF
jꢁjF
jj= P
jF
j; wR
¼
P
wðFo ꢁF Þ= wðF Þ
P
1=2
.
2
2
o
2
o
2
2
c
2
2
o
2
R
int
1
o
c
o
2

1
010
R. Ramírez-Trejo et al. / Polyhedron 29 (2010) 1007–1014
Fig. 1. (a) Tetrahedral cobalt(II) compound 3, electronic transitions due to low symmetry effects; (b) electronic transitions for [Co(SCN)
3
Br]2 in compound 6.
ꢁ
0
.38 mmol). The solution was stirred for 72 h. Solvent evaporation
3. Results and discussion
let blue crystals of compound 6 (20 mg, 16%). MS: m/z 207(12)
+
[
M] , 58(100), 118(78), 206(71), 117(66), 122(47). Mass + TOF calc.
Reactions of compound 1 with cobalt(II) and nickel(II) halides or
with copper(II) acetate, afforded compounds 3–5 (Scheme 2). The
coordination compounds were prepared by a template reaction
which involves condensation of one pair of 2-amino-thiazoles
and elimination of one NH3 molecule. In the coordination com-
pounds 3–5, the ligand forms three fused rings. The central ring
is a six-membered metallocycle. Two ligands are bound to a metal
atom, giving tetracoordinated metal centers.
for C10
H
13
N
2
S 207.0954, found: 207.0954. Mass ꢁTOF calc. for
Co 232.8586, found: 232.8592. Anal. Calc. for
CoBr
ꢀHSCN: C, 43.11; H, 4.79; N, 12.23; S, 18.66.
C
C
3
N
3
S
3
36
H
45
N
9
S
6
2
Found: C, 43.51; H, 4.91; N, 12.13; S, 18.96%.
2
.4. X-ray crystallographic study
The electronic spectra of the tetrahedral cobalt(II) 3 and nickel(II)
compounds merit some comments. As we will discuss below, the
Suitable single crystals of compounds 3–6 were mounted on a
4
glass fiber and covered with a small amount of perfluoro ether
oil. Data were collected at 293 K. Crystal data, data collection and
structure refinement details are given in Table 1. All data were
measured using standard procedures [31] on a Nonius Kappa
CCD instrument with CCD area detector using graphite-monochro-
X-ray structures show that the metal ion geometry is far from a reg-
ular tetrahedron, giving place to several electronic transitions due to
4
4
4
2 1 1
low symmetry effects, where the T terms, T (F), T (F) and T (P),
4
4
split into E and A, and the spin orbit coupling is a less important
perturbation than the lower symmetry field [34]. For the orange
cobalt(II) compound 3, these electronic transitions were observed
mated Mo Ka radiation at 293 K. Intensities were measured using
u + scans. A summary of data collection and refinements is given
x
in Table 1. All structures were solved using direct methods, using
2
SHELX-97 [32] and the refinement (based on F of all data) was per-
formed by full-matrix least-squares techniques with Crystals 12.87
Table 3
Selected bond angles (°) for 3–5.
[
33]. All non-hydrogen atoms were refined anisotropically. For
C
40
H
40
N
6
S
4
Co
C
40
H
40
N S
6 4
Ni
40 40 6 4
C H N S Cu
compounds 3 and 5, all hydrogen atoms were found in the differ-
ence map and their positions refined, while for compounds 4 and
(3)
(4)
(5)
Bond angles
6, all hydrogen atoms were found in the difference map and al-
(
(
(
N3)–(M1)–(N9)
N3)–(M1)–(N33)
N3)–(M1)–(N39)
92.9(11)
90.6(1)
123.5(1)
107.6(1)
107.1(1)
141.6(1)
90.8(1)
91.7(1)
134.7(1)
102.8(1)
102.2(1)
142.6(1)
91.8(1)
lowed to ride on their respective atoms, except for H18, H24,
H25, H35, H48, H51, H121, H193, H421 and H493 for compound
126.2(1)
108.0(1)
107.5(1)
134.3(1)
92.4(1)
130.3(3)
121.1(2)
130.9(3)
130.2(3)
120.1(3)
131.2(3)
4
and H7, H8, H141 and H142 for compound 6, whose coordinates
(N9)–(M1)–(N33)
(
(
(
(
(
(
N9)–(M1)–(N39)
N33)–(M1)–(N39)
N3)–(C2)–(N6)
C2)–(N6)–(C8)
N6)–(C8)–(N9)
N33)–(C32)–(N36)
were refined.
130.4(3)
119.0(3)
130.5(3)
129.9(3)
119.6(3)
130.7(3)
130.1(3)
119.4(3)
131.6(3)
130.5(3)
119.0(3)
131.0(3)
Table 2
Selected bond lengths (Å) for 3–5.
C
40
H
40
N
6 4
S Co
C
40
H
40
6
N S
4
Ni
C
40
H
40
6
N S
4
Cu
(C32)–(N36)–(C38)
(N36)–(C38)–(N39)
(3)
(4)
(5)
Bond lengths
(
(
(
(
(
(
(
(
(
(
(
(
M1)–(N3)
M1)–(N9)
M1)–(N33)
M1)–(N39)
C2)–(N3)
C2)–(N6)
C8)–(N6)
C8)–(N9)
C32)–(N33)
C32)–(N36)
C38)–(N36)
C38)–(N39)
1.969(2)
1.963(2)
1.950(2)
1.956(2)
1.310(4)
1.343(4)
1.334(4)
1.313(4)
1.305(3)
1.345(4)
1.338(3)
1.320(3)
1.934(3)
1.935(2)
1.946(2)
1.943(3)
1.301(4)
1.338(4)
1.330(4)
1.305(4)
1.298(4)
1.343(5)
1.328(4)
1.297(4)
1.959(2)
1.936(2)
1.938(2)
1.932(2)
1.293(4)
1.348(4)
1.335(4)
1.308(4)
1.304(4)
1.347(4)
1.337(4)
1.309(4)
Table 4
Selected data for C12
15 3 2
H N SCoBr (6).
Bond lengths (Å)
Co15)–(N17)
(Co15)–(Br16)
(C10)–(N9)
(C10)–(N14)
(C10)–(S11)
(C7)–(S11)
Bond angles (°)
1.97(1)
(Br16)–(Co15)–(N17)
(N9)–(C10)–(S11)
(N9)–(C10)–(N14)
(S11)–(C10)–(N14)
(C7)–(S11)–(C10)
109.6(2)
114.8(7)
124.8(7)
120.4(7)
92.0(4)
2.366(3)
1.32(1)
1.29(1)
1.728(7)
1.83(1)

R. Ramírez-Trejo et al. / Polyhedron 29 (2010) 1007–1014
1011
cluded, which its X-ray structure will be discussed below.
2
ꢁ
Compound 6 contains a cobaltate ion, [Co(SCN)
3
Br] , where the
expected electronic transitions for a cobalt(II) center in a regular
4
4
ꢁ1
tetrahedral geometry,
m
2
T
1
(F)
A
2
(F) at 7008 cm
(F) at 15 657 cm , are observed. Nickel(II) compound
, presents a similar tetrahedral low symmetry field spectrum, with
and m
3
4
4
ꢁ1
T
1
(P)
A
2
4
ꢁ
1
electronic transitions at 6793, 8745, 11 991, 16 917, 21 292 cm
and a broad charge transfer band at 25 658 cm . For the copper(II)
compound 5, transitions at 8646 and 15 714 cm , and a broad
charge transfer band at 23 796 cm , are observed.
ꢁ1
ꢁ1
ꢁ1
X-ray diffraction analyses of coordination compounds 3–5,
showed the same general structure. The metal atom is bound by
two bis(thiazolyl)amines through the imine nitrogen atoms. Se-
lected bond lengths and angles are summarized in Tables 2–4.
Fig. 2 shows the atom numbering scheme of the cobalt(II) com-
pound 3.
Fig. 2. Compound 3 ORTEP diagram with ellipsoids at 20% of probability.
In compounds 3–5, the metal atom participates in two six-
membered rings. The four metal–nitrogen bond lengths in each
compound are similar and relatively short (from 1.93 to 1.97 Å),
while the C–N bond lengths in the six-membered metallacycles
vary from 1.29 to 1.34 Å in between single and double bonds
S
N
S
N
N
(
the average distance of C–N and C@N bonds is 1.33 Å), indicating
M
an electronic delocalized -system with the participation of the
p
ꢁ
1
metal atom. The broad charge transfer band (10 000 cm ) in
their electronic spectra also shows the electronic delocalization,
as it has been observed in similar coordination compounds with
six-membered delocalized metallacycles derived from 2-(2-ben-
zothiazolylamino)benzothiazole [35], Scheme 4.
N
N
S
S N
Scheme 4. Coordination compounds derived from 2-(2-benzothiazolylamino)ben-
zothiazole M2 = Co, Ni, Zn, Hg [35].
+
In these compounds, the pentacyclic aromatic systems are al-
most perpendicular, which is not the case, of the present
compounds.
Molecules 3–5 are not symmetric. The four M–N bond lengths
present small differences as well as the angles around the metal
atoms. This effect is the result of a significant distortion, originated
ꢁ
1
at 8676, 11 749, 19 106, 21 526 cm and a broad charge transfer
band at 27 117 cm as shown in Fig. 1. In this figure, for comparison
purposes, the electronic spectrum of the cobalt(II) compound 6 is in-
ꢁ1
Fig. 3. Structure for the copper(II) compound 5, showing the rings conformation. C–Me is marked as E for equatorial position and A for axial position. Hydrogen and phenyl
groups have been omitted for clarity. The table shows the N–M–N angles in degrees for 3–5.
Fig. 4. X-ray diffraction structures of 4-methyl-5-phenyl-4,5-dihydro-selenazol-2-yl-amine (left) and (4S,5S)-3,4-dimethyl-5-phenyl-thiazolidin-2-yliden-ammonium ion
(
right) [25].

1
012
R. Ramírez-Trejo et al. / Polyhedron 29 (2010) 1007–1014
Fig. 5. Intramolecular SꢀꢀꢀH–C hydrogen bond distances in Å for compound 3.
Fig. 7. Dihedral angle between the planes of the fused tricycles in compound 5.
by the thiazole rings conformation. The three compounds present
the same conformational arrangement. Three of the thiazolyl rings
in each compound presents two substituents (methyl and phenyl)
in axial positions, whereas the fourth ring presents the substitu-
ents in equatorial position as is shown in Fig. 3 for the copper(II)
compound. The equatorial C–Me is marked as E, the axial C–Me
as A.
A possible explanation of this peculiar conformational behavior
can be found from the comparison between the solid state struc-
ture of the selenium analogue of compound 1 and the thiazolidini-
um cation of compound 6 (Fig. 4).
In the thiazolidinium ion, the steric effect of the endocyclic N–
Me group, which is in the ring plane, induces the C–Me and C–phe-
nyl to adopt axial positions. On the other hand, in the selenium
compound, the lack of a substituent at the endocyclic nitrogen
atom drives the C–Me group to adopt an equatorial position. In
compounds 3–5, one ring may adopt the more favored conforma-
tion with the methyl and phenyl groups in equatorial positions,
Fig. 8. Compound 6 ORTEP diagram with ellipsoids at 50% of probability.
E
by opening the contiguous N –M–NA1 angle. However, for the
other three rings, the steric effect makes their substituents to be
in axial positions (Fig. 3). The fact that one of the four rings has a
different conformation, explains the significant distortion in the
discussed compounds.
where the three equatorial C–H protons have shorter distances
P
2+
than the sum of van der Waals radii ( vdWr C–HꢀꢀꢀM, M = Ni, Co
or Cu (2.0 (M) + 1.2 (H) = 3.2 Å [37]), indicating a hydrogen bond-
ing interaction, while for the axial hydrogen (C–H, 3.286 Å) this
interaction does not occur. Additionally, protons from the methyl
groups may interact with the metal ions [38].
The structure adopted by the compounds is driven by the rings
conformation, which is also favored by different intramolecular
hydrogen bonding interactions. In Fig. 5, SꢀꢀꢀH–C hydrogen bonds
(
between an ortho proton of the phenyl group and the sulfur atom)
The tetrahedral distortion of the metal centers can be evaluated
according to Houser and co-workers [39] as a seesaw geometry
for compound 3 are shown, where the sulfur is acting as a Lewis
base. The SꢀꢀꢀH contacts (2.69–3.13 Å) are similar or shorter than
the reported distance of the highest incidence (3.21 Å) of this type
of contacts [36]. Other hydrogen interactions are depicted in Fig. 6,
(k
4
= 0.62, 0.67 and 0.70 for copper(II) 5, nickel(II) 4 and cobalt(II)
compounds). The distortion is also appreciated from the dihedral
angle between the planes of the fused tricycles. For cobalt(II) and
3
.
. .
Fig. 6. Co H–C hydrogen bond distances in Å for compound 3, (a) and (b). Spacefill representation of (b) is depicted in (c).

R. Ramírez-Trejo et al. / Polyhedron 29 (2010) 1007–1014
1013
Fig. 9. Intermolecular N–H Br (a) and C–HꢀꢀꢀBrꢁ(b) hydrogen bonds and SꢀꢀꢀS interactions (b) in compound 6.
.
. . ꢁ
nickel(II) compounds, the dihedral angle between the planes de-
scribed by the N–M bonds is near 70°, whereas in the copper(II)
compound this angle is only 59° (Fig. 7).
are stabilized in the coordination compounds, where one ligand
has both heterocycles with the phenyl and methyl groups in axial
positions, while the second ligand has a heterocycle with these
groups in equatorial positions, and on the other one, in axial posi-
tions. A mixed ionic compound formed by three (4S,5S)-3,4-di-
methyl-5-phenyl-thiazolidin-2-ylidene ammonium cations, one
tris-(thiocyano)bromide cobaltate dianion and one bromide, ob-
tained from reaction of (4S,5S)-3,4-dimethyl-5-phenyl-thiazoli-
2
The reaction of the thiocyanate salt 2 with CoBr in methanol
gave blue crystals of compound 6, which is a mixed ionic com-
pound (Scheme 3). X-ray diffraction analysis for this compound
shows three thiazol-2-ylidin ammonium cations, a bromide ion
and a tetrahedral cobaltate dianion. The latter has three thiocya-
nate groups and one bromide, Fig. 8. This compound presents di-
verse intermolecular interactions which are described below.
The Co–N (1.97(1) Å) and Co–Br (2.366(3) Å) bond lengths indi-
cate a strong coordination of the thiocyanate and the bromide to
the cobalt(II) atom, Table 4. The uncoordinated bromide is in close
contact with six N–H protons (2.59–2.83 Å), forming a slightly
irregular trigonal antiprism arrangement, with the bromide ion is
in its center. Sulfur–bromide short contacts are also present, where
the sulfur atom acts as a Lewis acid and the bromide anion as an
electron donor (Fig. 9a).
2
din-2-yliden-ammonium thiocyanate (2) and CoBr is described.
MetalꢀꢀꢀH–C, SꢀꢀꢀH–C interactions were observed in 3–6, whereas
in 6, also BrꢀꢀꢀH–N, BrꢀꢀꢀH–C and BrꢀꢀꢀS, SꢀꢀꢀS short contacts were
found.
5
. Supplementary data
CCDC 741947, 741948, 741949 and 741950 contains the sup-
plementary crystallographic data for 3, 4, 5 and 6. These data can
be obtained free of charge via http://www.ccdc.cam.ac.uk/conts/
retrieving.html, or from the Cambridge Crystallographic Data Cen-
tre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: (+44) 1223-336-
Sulfur–sulfur interactions are important in the structural stabil-
ization of crystalline arrangements of thiazolidines [40]. In the
present compound, three thiazolidine rings are interacting with
one cobaltate molecule. These are strong interactions, due to their
0
33; or e-mail: deposit@ccdc.cam.ac.uk.
almost perfect alignment and distance (3.44 Å), which is shorter
P
than the sum of the van der Waals radii ( vdWr 3.6 Å, [34]). In
Fig. 9b, this type of contacts is shown, where the thiazolidine
S11, behaves as an electron acceptor, while the cobaltate S19, as
an electron donor [41–42]. In this way, the sulfur–sulfur interac-
tions, together with Br–H bonds (2.9 Å) constitute a columnar mo-
tive of alternating thiazolidines and cobaltate dianions.
Acknowledgements
R.R. thanks for the post-doctoral DGAPA-UNAM fellow scholar-
ship. J.A.P.-H. thanks the Conacyt scholarship. E.M. post-doctoral
scholarship from Conacyt-060894. Financial support by DGAPA
IN206707 and Conacyt-060894 is acknowledged.
4
. Summary
References
[
1] M. Kaeriyama, S. Suga, A. Hashimoto, S. Sakai, Jpn. Kokai Tokkyo Koho (1983).
CODEN: JKXXAF JP 58157794 A 19830919 Showa. CAN 100:103397 AN
1984:103397.
Novel polydentate enantiomerically pure ligands were obtained
by metal template reactions. Condensation of two molecules of the
4R,5R)-4-methyl-5-phenyl-4,5-dihydro-thiazol-2-yl-amine, in the
presence of cobalt(II), nickel(II) and copper(II) ions, gave the corre-
sponding coordination compounds 3–5. These transition metals
compounds have in common a planar electronic delocalized
six-membered metallaring, where the metal ions show a great dis-
tortion from a regular tetrahedral geometry, originating complex
electronic spectra. Two conformations for the bis-thiazolyl ligand
(
[2] N. Kobayashi, K. Ueda, N. Itoh, S. Suzuki, G. Sakaguchi, A. Kato, A. Yukimasa, A.
Hori, Y. Kooriyama, H. Haraguchi, K. Yasui, Y. Kanda, PCT Int. Appl. (2008) 2.
CODEN: PIXXD2 WO 2008133273 A1 20081106 CAN 149:534229 AN
2008:1339943.
[3] K. Shankaran, K.L. Donelly, S.K. Shah, R.N. Guthikonda, M. MacCoss, J.L. Humes,
S.G. Pacholok, S.K. Grant, T.M. Kelly, K.K. Wong, Bioorg. Med. Chem. Lett. 14
(
2004) 4539.
[
4] A.A. Mandrugin, T.P. Trofimova, V.M. Fedoseev, S.Y. Proskuryakov, L.I. Shtein,
A.N. Proschin, A.N. Pushin, Pharm. Chem. J. 41 (2007) 640.

1
014
R. Ramírez-Trejo et al. / Polyhedron 29 (2010) 1007–1014
[
5] T. Castaño, A. Encinas, C. Pérez, A. Castro, N.E. Campillo, C. Gil, Bioorg. Med.
Chem. 16 (2008) 6193.
[26] A. Cruz, D. Macías-Mendoza, E. Barragán-Rodríguez, H. Tlahuext, H. Nöth, R.
Contreras, Tetrahedron Asymmetry 8 (1997) 3903.
[
[
[
[
6] H. Li, C.S. Raman, P. Martásek, V. Král, B.S.S. Masters, T.L. Poulos, J. Inorg.
Biochem. 81 (2000) 133.
7] S. Knapp, D. Vocadlo, Z. Gao, B. Kirk, J. Lou, S.G. Withers, J. Am. Chem. Soc. 118
[27] A. Cruz, A. Flores-Parra, H. Tlahuext, R. Contreras, Tetrahedron Asymmetry 6
(1995) 1933.
[28] A. Flores-Parra, P. Suarez-Moreno, S.A. Sánchez-Ruíz, M. Tlahuextl, R. Sálas-
Coronado, A. Cruz, H. Nöth, R. Contreras, Tetrahedron Asymmetry 9 (1998)
1661.
(
1996) 6804.
8] G.E. Whitworth, M.S. Macauley, K.A. Stubbs, R.J. Dennis, E.J. Taylor, G.J. Davies,
I.R. Greig, D.J. Vocadlo, J. Am. Chem. Soc. 129 (2007) 635.
9] T.K. Ritter, C.H. Wong, Tetrahedron Lett. 42 (2001) 615.
[29] E.V. Bakhmutova, H. Nöth, R. Contreras, B. Wrackmeyer, Z. Anorg. Allg. Chem.
627 (2001) 1846.
[
[
10] S. Kobayashi, H. Nakai, Y. Ikenishi, Y. Sun, M. Ozaki, Y. Hayase, R. Takeda, J.
Antibiot. 51 (1998) 328.
11] S. Kobayashi, S. Hidaka, Y. Kawamura, M. Ozaki, Y. Hayase, J. Antibiot. 51
[30] E.V. Bakhmutova, A. Cruz, R. Ramírez-Trejo, R. Contreras, B. Wrackmeyer,
Magn. Reson. Chem. 39 (2001) 739.
[31] Siemens, XSCAnS (release 2.21) Users Manual, Siemens Analytical X-ray
Instruments Inc., Madison, WI, USA, 1996.
(
1998) 323.
[
[
[
12] A. Ino, Y. Hasegawa, A. Murabayashi, Tetrahedron Lett. 39 (1998) 3509.
13] A. Ino, A. Murabayashi, Tetrahedron 55 (1999) 10271.
14] J. Levillain, G. Dubant, I. Abrunhosa, M. Gulea, A.C. Gaumont, Chem. Commun.
[32] G.M. Sheldrick, Acta Crystallogr., Sect. A 64 (2008) 112.
[33] P.W. Betteridge, J.R. Carruthers, R.I. Cooper, K. Prout, D.J. Watkin, J. Appl.
Crystallogr. 36 (2003) 1487.
(
2003) 2914.
[34] A.B.P. Lever, Inorganic Electronic Spectroscopy, second ed., Elsevier,
Amsterdam, 1984.
[35] F. Téllez, A. Peña-Hueso, N. Barba-Behrens, R. Contreras, A. Flores-Parra,
Polyhedron 25 (2006) 2363.
[
[
[
[
15] P. Wasserscheid, A. Bösmann, C. Bolm, Chem. Commun. (2002) 200.
16] H. Li, J. Yao, B. He, Sci. China, B: Chem. 40 (1997) 485.
17] H. Beyer, G. Berg, Chem. Ber. 89 (1956) 1602.
18] R. Takahashi, K. Kunimoto, P. Sutter, U. Lehmann, PCT Int. Appl. (2005) 2.
CODEN: PIXXD2 WO 2005081239, A1 20050901, CAN 143:257116, AN
[36] J.A. van den Berg, K.R. Seddon, Cryst. Growth Des. 3 (2003) 643.
[37] S.S. Batsanov, Inorg. Mater. 37 (2001) 871.
2
005:962534.
[38] M. Brookhart, M.L.H. Green, G. Parkin, Proc. Natl. Acad. Sci. USA 17 (2007)
6908.
[
[
19] W. Zhuang, T. Hansen, K.A. Jørgensen, Chem. Commun. (2001) 347.
20] K.B. Jensen, J. Thorhauge, R.G. Hazell, K.A. Jørgensen, Angew. Chem., Int. Ed. 40
[39] L. Yang, D.R. Powell, R. Houser, Dalton Trans. 2 (2007) 955.
[40] D.E. Lynch, Acta Crystallogr., Sect. C C60 (2004) o677.
[41] F. Téllez, A. Cruz, A.H. López-Sandoval, I. Ramos-García, M. Gayosso, R. Castillo-
Sierra, B. Paz-Michel, H. Nöth, A. Flores-Parra, R. Contreras, Eur. J. Org. Chem.
(2004) 4203.
(
2001) 160.
[
[
[
[
21] J. Zhou, Y. Tang, Chem. Commun. (2004) 432.
22] S. Yamazaki, Y. Iwata, J. Org. Chem. 71 (2006) 739.
23] R. Rasappan, M. Hager, A. Gissibl, O. Reiser, Org. Lett. 8 (2006) 6099.
24] A. Cruz, I.I. Padilla-Martínez, E.V. García-Báez, R. Contreras, Tetrahedron
Asymmetry 18 (2007) 123.
[42] A. Esparza-Ruiz, A. Peña-Hueso, J. Hernández-Díaz, A. Flores-Parra, R.
Contreras, Cryst. Growth Des. 7 (2007) 2031.
[
25] R. Ramírez-Trejo, Ph.D. Thesis, Cinvestav México, 2005.