Synthesis and characterization of thiosemicarbazone derivatives of 2-ethoxy-3-methoxy-benzaldehyde and their rhenium(I) complexes

Article abstract of DOI:10.1016/j.poly.2008.06.018

The ligands (HL¹, HL² and HL³) have been prepared and their reaction with fac-[ReX(CO)₃(CH₃CN)₂] (X = Br, Cl) in chloroform gave the adducts [ReX(CO)₃(HL)] (1a X = Cl, R = H; 1a′ X = Br, R = H; 1b X = Cl, R = CH₃; 1b′ X = Br, R = CH₃; 1c X = Cl, R = Ph; 1c′ X = Br, R = Ph) in good yield. All the compounds have been characterized by elemental analysis, mass spectrometry (FAB), IR and ¹H NMR spectroscopic methods, and the structures of the ligands have been elucidated by X-ray diffraction. In the case of HL¹, we have tried the reaction with [ReX(CO)₅] (X = Br, Cl) in toluene and we proved the formation of the adduct also by this way by the isolation of single crystals of 1a′ · 1/2C₇H_8.. In 1a′, the rhenium atom is coordinated by the sulfur and the azomethine nitrogen atoms, forming a five-membered chelate ring, as well as three carbonyl carbon and bromine atoms. The resulting coordination polyhedron can be described as a distorted octahedron. The study of the crystals obtained by slow evaporation of methanol solutions of the adducts 1b and 1c showed the formation of dimer structures based on rhenium(I) thiosemicarbazones [Re₂(L²)₂(CO)₆] (2b) and [Re₂(L³)₂(CO)₆] · 2(CH₃OH) (2c) · 2(CH₃OH). The thiosemicarbazonate complexes [Re₂(L)₂(CO)₆] (2) were obtained by reaction of the adducts with NaOH in dry methanol. In 2b and 2c · 2(CH₃OH) the dimer structures are established by Re-S-Re bridges, where S is the thiolate sulfur from a N,S-bidentate thiosemicarbazonate ligand. In both structures the rhenium coordination sphere is similar though, they are different in the ligand direction since centrosymmetric dimers are formed in 2c meanwhile in 2b are in the same diamond Re₂S₂ face.

Full text of DOI:10.1016/j.poly.2008.06.018

Polyhedron 27 (2008) 2867–2876
Contents lists available at ScienceDirect
Polyhedron
journal homepage: www.elsevier.com/locate/poly
Synthesis and characterization of thiosemicarbazone derivatives
of 2-ethoxy-3-methoxy-benzaldehyde and their rhenium(I) complexes
*
Ara Núñez-Montenegro, Rosa Carballo, Ezequiel M. Vázquez-López
Departamento de Química Inorgánica, Facultade de Química, Edificio de Ciencias Experimentais, Universidade de Vigo, E-36310 Vigo, Galicia, Spain
a r t i c l e i n f o
a b s t r a c t
The ligands (HL1, HL2 and HL3) have been prepared and their reaction with fac-[ReX(CO)3(CH3CN)2]
(X = Br, Cl) in chloroform gave the adducts [ReX(CO)3(HL)] (1a X = Cl, R = H; 1a0 X = Br, R = H; 1b X = Cl,
R = CH3; 1b0 X = Br, R = CH3; 1c X = Cl, R = Ph; 1c0 X = Br, R = Ph) in good yield. All the compounds have
been characterized by elemental analysis, mass spectrometry (FAB), IR and 1H NMR spectroscopic meth-
ods, and the structures of the ligands have been elucidated by X-ray diffraction. In the case of HL1, we
have tried the reaction with [ReX(CO)5] (X = Br, Cl) in toluene and we proved the formation of the adduct
also by this way by the isolation of single crystals of 1a0 ꢀ ½C7H8.
Article history:
Received 6 April 2008
Accepted 17 June 2008
Available online 26 July 2008
Keywords:
Thiosemicarbazone
Rhenium complexes
Carbonyl complexes
X-ray
In 1a0, the rhenium atom is coordinated by the sulfur and the azomethine nitrogen atoms, forming a five-
membered chelate ring, as well as three carbonyl carbon and bromine atoms. The resulting coordination
polyhedron can be described as a distorted octahedron.
The study of the crystals obtained by slow evaporation of methanol solutions of the adducts 1b and 1c
showed the formation of dimer structures based on rhenium(I) thiosemicarbazones [Re2(L2)2(CO)6]
(2b) and [Re2(L3)2(CO)6] ꢀ 2(CH3OH) (2c) ꢀ 2(CH3OH). The thiosemicarbazonate complexes [Re2(L)2(CO)6]
(2) were obtained by reaction of the adducts with NaOH in dry methanol.
In 2b and 2c ꢀ 2(CH3OH) the dimer structures are established by Re–S–Re bridges, where S is the thiolate
sulfur from a N,S-bidentate thiosemicarbazonate ligand. In both structures the rhenium coordination
sphere is similar though, they are different in the ligand direction since centrosymmetric dimers are
formed in 2c meanwhile in 2b are in the same diamond Re2S2 face.
Ó 2008 Elsevier Ltd. All rights reserved.
1. Introduction
The literature for cardiac perfusion tracers suggest that ether
groups can be used to modulate lipophility and physicochemical
The use of the fac-[M(CO)3]+ (M = 99mTc and Re) core has been
explored widely as diagnostic or radio- and chemotherapeutic
agents. For example, Alberto’s group has recently shown that
[M(H2O)3(CO)3]+ forms complexes with guanine with rate con-
stants of the same order of magnitude as one of the active deriva-
tives of cisplatin [Pt(NH3)2(H2O)2]2+ [1,2]. However, this compound
interacts unspecifically with potential coordination sites of human
proteins in serum [3]. Therefore, to maintain the availability of the
fragment fac-[M(CO)3]+ in relevant concentrations for therapeutic
use, the protection of coordination sites is required by ligands that
must also be sufficiently labile to be displaced by targeted mole-
cules. In addition, from a therapeutic point of view, the presence
of three carbonyl groups reduces molecular weight of the agent
and its non-specific uptake could decrease [4].
parameters (molecular weight and volume) that greatly influence
cardiac uptake, membrane diffusion, and plasma protein binding.
In fact, ether substituents are commonly employed in commercial
cardiac perfusion agents such as CARDIOLITEÒ (BMS) and MYO-
VIEWÒ (G.E. Healthcare).
Thiosemicarbazones (TSCs) are very versatile ligands that can
coordinate as neutral ligands or in their deprotonated form, so they
can have an important variety of coordination modes [5–7]. The
inclusion of potential donors groups has been explored to increase
ligand denticity or the introduction of organic/metal–organic
groups that give the complex molecule different properties. The
introduction of 2-pyridincarbaldehyde, 2-acetylpyridine [8], 2,20-
dipyridilcetone [9] and 4-acetylpyridine [10] fragments showed
the effects of these donors groups in the thiosemicarbazide chain
proximities on the coordination behaviour, or the ferrocenylcarbal-
dehyde group [11] allowed to study the capacity of the TSCs to
communicate the metal and the redox units through the TSC chain.
Furthermore, these types of ligands and their complexes have
received considerable attention according to their biological activ-
ity. In a recent revision of the pharmacological properties of thio-
On the other hand, the studies of Tc(I) tracers agents designed
for cardiac perfusion suggested that they must be sufficiently lipo-
philic for their incorporation and retention in the myocardium [4].
* Corresponding author.
E-mail address: ezequiel@uvigo.es (E.M. Vázquez-López).
0277-5387/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2008.06.018

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A. Núñez-Montenegro et al. / Polyhedron 27 (2008) 2867–2876
semicarbazone complexes, Quiroga and Navarro have observed the
sensible increase in the number of studies of their antibacterial,
antiviral, antifungal and antitumour activity [12]. For instance, a
report of CuII, ZnII, CdII or HgII complexes with thiosemicarbazone
derived from vanillin shows their activity against pathogen fungus
belonging to the groups Alternaria (sp.), Paecilomyces (sp.) and Pest-
alotia (sp.) [13].
In the present work we have chosen thiosemicarbazones with
the group 2-ethoxy-3-methoxy-benzaldehyde, which can be con-
sidered a ester derivative similar of vanillin, and the fragment
fac-[Re(CO)3]+. Besides the interesting bioinorganic properties
mentioned above, the exploration of the coordinative behaviour
of these ligands against tricarbonylrhenium(I) and the structures
resulting of their molecular association and their spectroscopic
behaviour, is also worth to be studied.
contains a signal corresponding to the molecular ion, although the
peak due to the species [MꢁX]+ is more intense.
Furthermore, facial geometry around the rhenium atom is sug-
gested by the three strong bands
m
(C„O) in IR (sometimes col-
The ligand bands
lapsed) in the range 1889–2027 cmꢁ1
.
corresponding to the N–H groups appear between 3181 and
3508 cmꢁ1 and are hardly modified by coordination. Regarding
the typical bands from the thiosemicarbazide fragment, the fre-
quencies of the band C@N, in the free ligands in the range 1543–
1556 cmꢁ1, shift to the region 1555–1630 cmꢁ1 in the spectra of
all the complexes. Nevertheless, the band corresponding to the
C@S mode shifts from 783 to 788 cmꢁ1 in free ligands to 740–
771 cmꢁ1 in the rhenium complexes, in agreement with the coor-
dination of the ligand by the sulfur atom. This behaviour has been
observed in other TSC complexes and it is consistent with the S,N
coordination of the ligand [8,11,14,15].
In general, all proton signals in the 1H NRM spectra in acetone-
d6 of the complexes are shifted at low field (around 0.5 ppm) re-
spect the free ligands. Differently, the signal of the N(2)–H proton
moves around 2 ppm. Similar behaviour has been observed in rhe-
nium(I) complexes of hydrazones [16] and thiosemicarbazones
[11,14], where the N(2)–H group is a member of the chelate ring
resulting after the S,N-coordination. However, when the thiosemi-
carbazone is coordinated as a S-monodentate ligand, the N(2)–H
proton signal behaves as the rest of the ligand signals [10].
To explore the influence of temperature and nature of the rhe-
nium precursor in the reaction product, the reaction of HL1 with
[ReX(CO)5] were tested in toluene. In the bromine derivative, the
2. Results and discussion
2.1. Synthesis and spectroscopic characterization
The ligands derived from 2-ethoxy-3-methoxy-benzaldehyde
thiosemicarbazone were obtained by refluxing a mixture metha-
nol/water solution for 2 h (Scheme 1).
Reaction of the three ligands with fac-[ReX(CO)3(CH3CN)2]
afforded six adducts (Scheme 2) with general formula fac-[Re-
X(CO)3(HL)] (1).
Elemental analysis and mass spectrometry confirmed the stoi-
chiometry [ReX(CO)3(HL)]. The mass spectra of the metallic species
Scheme 1.
[ReX(CO)3(NCCH3)2]
CHCl3, r.t.
OMe
OEt
H
R
X
H
N
1
N
S
1a
H
Cl
Br
H
N
1a'
H
MeO
OEt
N
RHN
H
NHR
C7H8, b.p.
[ReBr(CO)5] + HL1
1b
Me
Me
Cl
Br
1b'
S
(OC)3XRe
1c
Ph
Ph
Cl
Br
1c'
NaOH
OMe
R
H
2a
2b
2c
H
OEt
N
N
Me
Ph
(OC)3Re
NHR
2
S
2
Scheme 2.

A. Núñez-Montenegro et al. / Polyhedron 27 (2008) 2867–2876
2869
characterization of the product showed the formation of the same
adduct, [ReBr(CO)3(HL1)] (1a0), exclusively. However when the
chloride derivative was used, the spectroscopic data suggested
the coexistence of the compound 1a and also some product deri-
vate of the deprotonation.
quencies of C@N bonds shift to a larger wavenumbers than in free
ligands (1610–1710 cmꢁ1).
The 1H NMR spectra of these compounds in acetone-d6 show all
the proton signals shifted at low field respect to the free ligands
and as expected the signals for N(2)–H are absent.
On the other hand, the X-ray study of the crystals obtained from
methanol solutions 1b and 1c showed the formation of binuclear
thiosemicarbazonate complexes (Scheme 2). In a process similar
to observed in the rhenium(I) complex of ferrocenylaldehyde thio-
semicarbazone [11], the deprotonation of the TSC ligand induces
the labilization of the halogen in a position occupied by sulfur
atom from other TSC coordinated.
These complexes 2a, 2b and 2c were obtained by reaction of
bromine derivatives, 1a0, 1b0 and 1c0, with NaOH in methanol. In
all of them, the three carbonyl IR bands are consistent with the fa-
2.2. Crystal and molecular structure of the ligands
The molecular structures of the free ligands are shown in Fig. 1
along with the atomic numbering scheme used. Crystal data and
selected bond lengths and angles are listed in Tables 1 and 2,
respectively.
Ligands HL1 and HL2 crystallized as mono- and hemi-hydrates,
respectively, and the water molecule is linked by hydrogen bond
to the oxygen atom of the ethoxy group (O(1)W). The role of this
molecule in both structures is discussed in detail below. In HL2,
two TCS ligand molecules per asymmetric unit were identified
showing differences between distances and angles statistically
insignificant and, consequently, the average values are including
in Table 2.
cial geometry around rhenium atom, and the m(C@S) bands at 714–
740 cmꢁ1, suggest some weakening of the bond. The vibration fre-
In all the cases, the distances C(1)–S(1), C(2)–N(3), N(2)–N(3)
and N(2)–C(1) suggest that, in spite of the usual delocalization of
p
electrons along the thiosemicarbazide chain [17], the canonical
form of the free ligand depicted in Scheme 1 is likely the main form
in solid state.
The molecular structure of these ligands shows E configuration
around C(1)–N(2), N(2)–N(3), N(3)–C(2) and C(2)–C(3) bonds.
However, Z configuration in the C(1)–N(1) bond has been linked
with the existence of intramolecular hydrogen-bonding interac-
tions N(1)–HꢀꢀꢀN(3). The distance N(1)–N(2) decrease from
HL1 ꢂ HL2 > HL3 (Table 3). Before conclude that the shortening is
due to the increasing of the interaction strength, note that the an-
gle N(1)–C(1)–S(1) widen following the same path. Thus, these
findings are also compatible with the increase of steric hindrance
of the R group linked to N(1) and the sulfur atom.
In the three cases, the molecule of the ligand can be considered
planar: the angles between the ideal plane of the thiosemicarba-
zide chain N(1)/S(1)/C(1)/N(2)/N(3)/C(2) and the carbon atoms
that define the phenyl ring are 7.34(3)°, 6.67(8)° and 2.4(2)° for
HL1, HL2 and HL3, respectively.
Table 1
Crystal data, data collection and refinement of the structures of HL1 ꢀ H2O, HL2 ꢀ 1/
2H2O and HL3
Compound
HL1 ꢀ H2O
HL2 ꢀ 1/2H2O
HL3
Empirical formula
Molecular weight
Space group
Unit cell dimensions
a (Å)
C11H17N3O3S
271.34
C2/c
C12H18N3O2.5
276.35
P21/n
S
C17H19N3O2S
329.41
C2/c
20.260(5)
7.0868(19)
20.581(5)
113.081(5)
2718.4(12)
8
14.893(3)
10.0714(17)
19.671(3)
101.779(3)
2888.4(8)
8
30.219(6)
5.6664(11)
20.127(4)
101.714(4)
3374.6(12)
8
b (Å)
c (Å)
b (°)
V (Å3)
Z
Dcalc (Mg/m3)
1.326
0.243
1.271
0.227
1.297
0.205
l
(mmꢁ1
)
h Range (°)
Reflections collected
2.19–28.04
7029
1.92–28.05
14981
2.07–28.03
7626
Independent reflections (Rint
)
3010
(0.0863)
0.969/0.672
6149 (0.0297) 3408
(0.0518)
Maximum/minimum
transmission
0.930/0.894
0.966/0.865
Goodness-of-fit on F2
0.775
1.065
0.906
Final R1/wR2 indices [I > 2
r(I)]
0.0548/
0.0909
0.1902/
0.1160
0.0444/
0.1127
0.0765/
0.1243
0.0648/
0.1603
0.1445/
0.1957
R1/wR2 indices (all data)
Fig. 1. Molecular structures of HL1 ꢀ H2O (A), HL2 ꢀ 1/2H2O (B) and HL3 (C).

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A. Núñez-Montenegro et al. / Polyhedron 27 (2008) 2867–2876
The HL3 molecules are also coupled N(2)–HꢀꢀꢀS(1)#5 by hydrogen
bond (Fig. 2E) and the dimers are associated in a herringbone pat-
tern by weak interactions involving methoxy and aromatic C–H
Table 2
Selected bond lengths (Å) and bond angles (°) for HL1 ꢀ H2O, HL2 ꢀ 1/2H2O and HL3
HL1 ꢀ H2O
HL2 ꢀ 1/2H2Oa
HL3
groups as H-donors and oxygen atom (ethoxy) or
acceptors, respectively (Fig. 2F).
p-clouds as
S(1)–C(1)
N(1)–C(1)
N(1)–C(9)
N(2)–C(1)
N(2)–N(3)
N(3)–C(2)
C(2)–C(3)
1.691(3)
1.320(3)
1.686(11)
1.323(3)
1.442(3)
1.352(2)
1.374(2)
1.276(2)
1.464(3)
1.681(4)
1.329(4)
1.414(4)
1.349(4)
1.373(4)
1.275(4)
1.456(5)
2.3. Crystal and molecular structure of [ReBr(HL1)(CO)3] ꢀ ½C7H8
(1a0 ꢀ ½C7H8)
1.340(3)
1.376(3)
1.276(3)
1.462(4)
Single crystals of the complex 1a0, obtained from the mother li-
quor (toluene) contains one solvent molecule per each two mole-
cules of the complex. The toluene molecule is in the cell origin
and, consequently, disordered. In the final model we have consid-
ered the methyl group on two alternate positions with occupation
factors 50% and the aromatic ring centre at the origin. Moreover,
two independent molecules that correspond to the two enantiomer
of the fac configuration (OC-6-33) appear in the asymmetric,
although there are also differences concerning the relative orienta-
tion of the aromatic ring and the bromo ligand.
N(1)–C(1)–N(2)
N(1)–C(1)–S(1)
N(2)–C(1)–S(1)
C(1)–N(2)–N(3)
C(2)–N(3)–N(2)
N(3)–C(2)–C(3)
C(1)–N(1)–C(9)
117.7(2)
122.6(2)
119.8(2)
119.8(2)
114.7(2)
120.7(3)
116.8(18)
124.2(15)
119.0(16)
120.1(17)
115.8(17)
120.9(19)
124.7(18)
114.2(3)
127.9(3)
117.9(3)
120.8(3)
115.3(3)
121.5(3)
132.9(3)
a
Average values and standard deviation estimated by the expressions
P
P
P
x ¼ ð xj=r2j Þ= 1=rj2 and r2ðxÞ ¼ 1= 1=r2j
.
The molecular structure of (1a0 ꢀ ½C7H8) together the number-
ing scheme used is depicted in Fig. 3A. Crystal data and relevant
interatomic distances and angles relative to the coordination
sphere are included in Tables 4 and 5, respectively.
Table 3
Parameters (Å, °) of H-bonding interactions in HL1 ꢀ H2O, HL2 ꢀ 1/2H2O and HL3
D–HꢀꢀꢀAa
HL1 ꢀ H2O
d(D–H)
d(HꢀꢀꢀA)
d(DꢀꢀꢀA)
\(DHA)
The ligand HL1 is coordinated to Re(I) through the sulfur and
azomethine nitrogen N(3) atoms. This coordination mode changes
the configuration of the bond C(1)–N(2) from E, observed in the
structure of free ligand HL1 (vide supra), to Z to forms a five-mem-
bered chelate ring. This ring is approximately planar and the angles
respect to the aromatic ring are 39.4(3)° (Re(1) molecule) and
50.3(4)° (Re(2) molecule). The rhenium atom is octahedrally coor-
dinated to three carbonyl carbon atoms in fac arrangement, a bro-
mine atom, the azomethine nitrogen and the sulfur atom of the
thiosemicarbazone, main distortion being in the angle S–Re–N
(<80°) due to the formation of the chelate ring. The bond distances
in Re–N(3), Re–S and Re–Br are statistically equivalent in both mol-
ecules and they are very similar to observed previously in others
fac-Re(CO)3 adducts with TSC chelate ligands [8,9,11,14].
N(1)–H(1A)ꢀꢀꢀN(3)
N(1)–H(1A)ꢀꢀꢀO(1W)
N(2)–H(2)ꢀꢀꢀS(1)#1
N(1)–H(1B)ꢀꢀꢀO(1W)#2
O(1W)–H(1W)ꢀꢀꢀS(1)#2
O(1W)–H(2W)ꢀꢀꢀO(1)#3
0.86
0.86
0.86
0.86
0.83(3)
0.91(4)
2.29
2.22
2.54
2.39
2.58(4)
2.02(4)
2.637(3)
2.965(3)
3.394(3)
3.136(4)
3.330(3)
2.923(4)
104.5
145.2
171.1
145.2
150(3)
175(4)
HL2 ꢀ ½H2O
N(1A)–H(1A)ꢀꢀꢀN(3A)
N(1B)–H(1B)ꢀꢀꢀN(3B)
N(1A)–H(1A)ꢀꢀꢀO(1W)
N(2A)–H(2AN)ꢀꢀꢀS(1B)
N(2B)–H(2BN)ꢀꢀꢀS(1A)
O(1W)–H(1W)ꢀꢀꢀO(1A)#4
0.86
0.86
0.86
0.86
0.86
0.88(3)
2.23
2.27
2.28
2.59
2.55
2.15(3)
2.624(2)
2.652(2)
2.988(3)
3.4365(18)
3.3900(18)
3.009(3)
107.8
107.3
139.5
167.5
165.4
164(3)
HL3
N(1)–H(1)ꢀꢀꢀN(3)
0.86
0.86
2.13
2.64
2.601(3)
3.441(3)
113.9
154.5
N(2)–H(2)ꢀꢀꢀS(1)#5
Aside the change of the configuration in the bond C(1)–N(2), the
coordination of HL1 to rhenium modifies also the configuration
about the C(2)–N(3) bond to Z. Both changes and the non-planar
structure of the ligand are likely due to steric hindrances between
the aromatic ring, and its ether group, with the fragment {Re(CO)3}.
Finally, respect to the molecular structure, the non-planar
structure of TSC and the metallic fragment asymmetry, allows
the coexistence of two possible distributions of 2-ethoxy-3-meth-
oxy-benzaldehyde fragment: one with the group positioned to the
direction occupied by the bromine atom and the other in the oppo-
site direction. Both are in the crystal and probably coexist also in
solution but, in contrast to ferrocenyl derivatives, they no produce
different signals in the 1H NMR spectrum [11].
The description of the molecular packing in the crystal is com-
plex since the two enantiomers are associated in different fashion.
Beside the weak C–Hꢀꢀꢀacceptor interactions, the Re(1) molecule is
associated with other symmetrically equivalent molecules (Fig. 3B)
by hydrogen bonds between N–H azomethine and thioamide
groups and the bromine atom (N(1A)–H(1A1)ꢀꢀꢀBr(1)#1 = 0.86,
2.557, 3.372(8) Å, 158.54; N(2A)–H(2A2)ꢀꢀꢀBr(1) = 0.86, 2.939,
3.465(8) Å, 147.78°; #1 = ꢁx + 2, ꢁy + 2, ꢁz + 1). These associa-
tions, and the metric values from these interactions, have been ob-
served in other rhenium(I) thiosemicarbazones derived from
ferrocenylcarbaldehyde [11] and b-keto esters [14]. In the present
case, the two interactions are reinforced by an additional interac-
tion which involve the thioamide nitrogen and the ethoxy group
from the partner molecule.
a
Symmetry transformations used to generate equivalent atoms: #1 = ꢁx, y,
ꢁz + ½; #2 = ꢁx, ꢁy + 2, ꢁz + 1; #3 = ꢁx ꢁ ½, y + ½, ꢁz + ½; #4 = ꢁx, ꢁy, ꢁz;
#5 = ꢁx, ꢁy ꢁ 1, ꢁz + 1.
The molecular association in HL1 ꢀ H2O is strongly dominated by
the presence of the water molecule. Two HL1 molecules are associ-
ated with two water molecules by N(1)–HꢀꢀꢀO(1W) interactions
(Table 3) showing in both cases the water molecule an acceptor
hydrogen behaviour (Fig. 2A). The interaction between a sulfur
atom from TSC and the water, which is now a H-bond donor, prob-
ably assists to the formation of these ‘‘virtual molecular-tetramer”.
These units are associated by N(2)–HꢀꢀꢀS(1) interactions along the c
axis. In turn, these chains are associated by hydrogen bonds be-
tween water and the oxygen atoms, O(1), from a neighbouring eth-
oxy group in the brick-wall-like arrangement showed in Fig. 2B.
As mentioned before, two molecules of HL2 can be observed per
asymmetric unit. Though important differences are not observed in
molecular distances and angles, the differences become more
marked when the crystal packing is considered. One of the HL2
molecules is associated with other, crystallographically equivalent
(labelled A in Fig. 2C) by two water molecules as in HL1, involving
two hydrogen bonds pairs N(1A)–HꢀꢀꢀO(1W) and O(1W)–HꢀꢀꢀO(1A)
(Table 3). These molecules are also associated with molecules non-
crystallographically equivalent (labelled B) by N(2A)–HꢀꢀꢀS(1B) and
N(2B)–HꢀꢀꢀS(1A) interactions (Fig. 2C). These units formed by four
ligand molecules and two water molecules are packed by weak
contacts O(1W)–Hꢀꢀꢀ
p
, in a herringbone pattern as usually observed
In addition, the interactions between molecules containing
Re(2) atom, involve the bromine atom in a very similar way to
in aromatic derivatives.

A. Núñez-Montenegro et al. / Polyhedron 27 (2008) 2867–2876
2871
Fig. 2. Supramolecular association in HL1 ꢀ H2O (A and B), HL2 ꢀ ½H2O (C and D) and HL3 (E and F).
Re(1) molecules, but now, the N(1B)–H group establishes H-bonds
(N(1B)–H(1B2)ꢀꢀꢀO(1B)#2 = 0.86, 2.50, 2.934(11) Å, 111.9°; N(1B)–
H(1B2)ꢀꢀꢀO(2B)#2 = 0.86, 2.19, 3.042(10) Å, 171.5°; #2 = ꢁx, 1 ꢁ y,
ꢁz) with the ether groups of a neighbouring molecule. Conse-
quently, dimers are associated in chains running parallel to a axis
(Fig. 3C).

2872
A. Núñez-Montenegro et al. / Polyhedron 27 (2008) 2867–2876
Fig. 3. The molecular structure (A) and crystal packing (B–D) in 1a0 ꢀ ½C7H8.
Finally, the molecular packing is completed with weak interac-
occupied by the halogen atom creates dimers. A difference be-
tween both, is that in 2c this interaction produces centrosymmet-
ric dimers, similar to observed in the ferrocenylcarbaldehyde
thiosemicarbazonates [11] but in 2b both thiosemicarbazonate
groups are in the same side of the Re2S2 fragment. This different
group orientation and the formation of the Re2S2 diamond, does
not impose important differences in bond lengths and angles
(Table 6).
tions between donor C–H groups and carbonyl as acceptors and
can be described considering the packing of the chains of Re(2)
molecules, in b direction, hosts the Re(1) dimers and toluene mol-
ecules (Fig. 3D).
2.4. Crystal and molecular structure of [Re2(L2)2(CO)6] (2b) and
[Re2(L3)2(CO)6] ꢀ 2CH3OH (2c ꢀ 2CH3OH)
The rhenium atoms retains its octahedral coordination, but now
interacts with two sulfur atoms, and the sulfur belonging to the
partner in the dimer, is farther away than its own sulfur. In fact,
the Re–S–Re bridge is relatively asymmetric, as in others dimer
structures based on this type of interaction [18,19]. In the diamond
Re2S2, the bond angles close to 90° and the distance Re–Re is too
long (>3.75 Å) for means any significant bonding interaction.
As observed in ferrocenyl derivatives [11], the Re–N(3) and Re–
S(1A) distances are statistically equivalents to the observed in 1a0.
However, the C(1)–S(1) distance is longer than in the free ligands
or the adduct 1b, in agree with a higher thiol character. In addition,
the angle between the plane of benzaldehyde ring and the TSC
Single crystals of 2b and 2c were obtained by slow concentra-
tion from methanol solutions of the previously isolated adducts.
The observed disorder of the methyl or the ethoxy group was mod-
ulated by refinement of two alternate positions for these groups
with occupancies of 80% and 25%. Crystal and structure refinement
data for both compounds are showed in Table 4. Relevant length
bonds and angles are included in Table 5 meanwhile the molecular
structures, showing the numbering scheme used are depicted in
Fig. 4.
The ligand deprotonation and the interaction of the rhenium
with the sulfur atom of a neighbouring molecule at the position

A. Núñez-Montenegro et al. / Polyhedron 27 (2008) 2867–2876
2873
Table 4
In 2c, the presence of methanol affects the association of the
centrosymmetric dimers. The two molecules of methanol are sym-
metrically independents and they are associated by O(2M)–
HꢀꢀꢀO(1M) bonds and at the same time, one of them establishes a
hydrogen chelate bond with two oxygen atoms of the methoxy
and ethoxy group (O(1M)–H(1M)ꢀꢀꢀO(2) = 0.82, 2.083, 2.844(8) Å,
154.08°; O(1M)–H(1M)ꢀꢀꢀO(1) = 0.82, 2.592, 3.221(7) Å, 134.56°).
The other methanol molecule behaves as hydrogen bond acceptor
Crystal data and structure refinement of rhenium(I) complexes
Compound
1a0 ꢀ ½C7H8
2b
2c ꢀ 2(CH3OH)
Empirical formula
Formula weight
Space group
Unit cell dimensions
a (Å)
C15.5H15N3O5SReBr C30H32N6O10S2Re2 C40H36N6O10S2Re2
623.49
1073.14
P21/c
1325.44
ꢀ
ꢀ
P1
P1
8.0343(9)
15.5310(17)
16.9500(18)
93.907(2)
98.804(2)
96.164(2)
2070.3(4)
4
2.000
7.930
1.88–28.03
13435
10.6586(9)
16.9065(15)
21.3813(19)
7.9039(6)
12.6770(9)
13.6465(10)
64.4370(10)
82.0500(10)
89.9540(10)
1218.99(16)
1
1.806
5.177
1.78–28.01
8019
b (Å)
c (Å)
with the N–H group of a neighbour dimer (N(1)–H(1)ꢀꢀꢀO(2M)#1
=
0.86, 1.976, 2.830(8) Å, 171.65°; #1 = ꢁx, ꢁy, 2 ꢁ z). These interac-
tions make ribbons running transverse to the crystallographic
directions a and b.
a
(°)
b (°)
91.009(2)
c
(°)
V (Å3)
3852.3(6)
4
1.850
6.588
1.91–28.03
24785
Z
Dcalc (Mg/m3)
l
(mmꢁ1
)
3. Experimental
h Range (°)
Reflections
collected
3.1. Materials and methods
Independent
reflections (Rint
Maximum/
minimum
9455 (0.0462)
0.530/0.357
9143 (0.0857)
0.433/0.279
5596 (0.0223)
0.541/0.233
All solvents used for synthesis were dried over appropriate dry-
ing agents, degassed using a vacuum line and distilled under an Ar
atmosphere [20]. Adducts [ReX(CO)3(CH3CN)2] were synthesized
by Farona and Kraus’ published methods [21] from the correspond-
ing [ReX(CO)5] [22].
)
transmission
Goodness-of-fit on
0.966
0.997
1.097
F2
Final R1/wR2 indices 0.0527/0.0945
[I > 2 (I)]
0.0521/0.1150
0.1371/0.1481
0.0264/0.0652
0.0311/0.0781
Elemental analyses were carried out on a Fisons EA-1108. Melt-
ing points (mp) were determined on a Gallenkamp MFB-595 and
are uncorrected. Mass spectra were recorded on a VG Autospec
Micromass spectrometer operating under FAB conditions (nitro-
benzyl alcohol matrix). Infrared spectra were recorded from KBr
pellets on a Bruker Vector 22FT. The 1H NMR spectra were obtained
on a Bruker ARX-400 spectrometer from acetone-d6 solutions.
r
R1/wR2 indices (all
0.1382/0.1209
data)
Table 5
Relevant interatomic distances (Å) and angles (°) for the complex
[ReBr(CO)3(HL1)] ꢀ ½C7H8 (1a0 ꢀ ½C7H8)
3.2. General synthesis of the ligands HL1, HL2 and HL3
Re(1)–C(101)
Re(1)–C(102)
Re(1)–C(103)
Re(1)–N(3A)
Re(1)–S(1A)
Re(1)–Br(1)
S(1A)–C(1A)
N(1A)–C(1A)
C(1A)–N(2A)
N(2A)–N(3A)
1.919(12)
1.869(12)
1.875(13)
2.196(8)
Re(2)–C(201)
Re(2)–C(202)
Re(2)–C(203)
Re(2)–N(3B)
Re(2)–S(1B)
Re(2)–Br(2)
S(1B)–C(1B)
N(1B)–C(1B)
C(1B)–N(2B)
N(2B)–N(3B)
1.933(16)
1.893(13)
1.794(18)
2.204(8)
To a mixture of a water solution (15 mL) of thiosemicarbazide
and a methanol solution (15 mL) of 2-ethoxy-3-methoxy-benzal-
dehyde was added one H2SO4(c) drop. To avoid the precipitation
of 2-ethoxy-3-methoxy-benzaldehyde some methanol (about
15 mL) was added. The reaction mixture was heated under reflux
for 2 h. The resulting solid was filtered off and vacuum dried over
KOH/CaCl2. Single crystals were obtained after slow evaporation of
the mother liquor.
2.462(3)
2.455(3)
2.6380(12)
1.682(10)
1.318(11)
1.346(11)
1.374(10)
2.6452(14)
1.680(11)
1.312(12)
1.350(11)
1.359(10)
C(102)–Re(1)–C(101)
C(102)–Re(1)–C(103)
C(103)–Re(1)–C(101)
C(102)–Re(1)–N(3A)
C(103)–Re(1)–N(3A)
C(101)–Re(1)–N(3A)
C(102)–Re(1)–S(1A)
C(103)–Re(1)–S(1A)
C(101)–Re(1)–S(1A)
N(3A)–Re(1)–S(1A)
C(102)–Re(1)–Br(1)
C(103)–Re(1)–Br(1)
C(101)–Re(1)–Br(1)
N(3A)–Re(1)–Br(1)
S(1A)–Re(1)–Br(1)
N(2A)–C(1A)–S(1A)
C(1A)–N(2A)–N(3A)
C(2A)–N(3A)–N(2A)
86.6(5)
89.4(5)
88.9(4)
174.5(4)
95.7(4)
95.4(4)
98.6(3)
92.4(3)
174.7(3)
79.3(2)
88.8(3)
176.2(3)
94.4(3)
85.97(19)
84.54(8)
122.7(8)
121.0(8)
118.0(8)
C(202)–Re(2)–C(201)
C(203)–Re(2)–C(202)
C(203)–Re(2)–C(201)
C(202)–Re(2)–N(3B)
C(203)–Re(2)–N(3B)
C(201)–Re(2)–N(3B)
C(202)–Re(2)–S(1B)
C(203)–Re(2)–S(1B)
C(201)–Re(2)–S(1B)
N(3B)–Re(2)–S(1B)
C(202)–Re(2)–Br(2)
C(203)–Re(2)–Br(2)
C(201)–Re(2)–Br(2)
N(3B)–Re(2)–Br(2)
S(1B)–Re(2)–Br(2)
N(2B)–C(1B)–S(1B)
C(1B)–N(2B)–N(3B)
C(2B)–N(3B)–N(2B)
90.0(5)
86.9(6)
89.6(7)
174.5(5)
93.3(5)
95.5(4)
95.4(4)
92.2(6)
174.4(3)
79.1(2)
94.8(4)
178.2(4)
89.9(5)
85.0(2)
88.17(9)
122.2(8)
121.7(8)
117.3(8)
3.2.1. Data for HL1
Thiosemicarbazide (500 mg, 5.49 mmol)/2-ethoxy-3-methoxy-
benzaldehyde (0.5 mL, 3.08 mmol). White crystalline solid. Yield:
1783 mg (89.2%). M.p.: 185 °C. Anal. Calc. for C11H15N3O2S: C,
52.1; H, 6.0; N, 16.6; S, 12.6. Found: C, 52.2; H, 6.1; N, 16.4; S,
12.6%. Mass spectrum [m/z (%)]: 254.11(100) [M]+. IR data (KBr,
cmꢁ1): 3482m, 3442m, 3282m
m
m
(NH); 1543s
m(C@N); 783w
(C@S). 1H NMR data (ppm): 10.55s (1) d(N(2)–H); 8.55s (1)
d(C(2)–H); 7.83s (1) d(N(1)–H); 7.62m (1) d(C(7)–H); 7.43s (1)
d(N(1)–H); 7.05s (1) d(C(6,8)–H); 7.04s (1) d(C(6,8)–H); 4.06m (2)
d(O(4)–R2); 3.85s (3) d(O(5)–R3); 1.34m (3) d(O(4)–R2).
3.2.2. Data for HL2
4-Methyl-3-thiosemicarbazide (500 mg, 4.75 mmol)/2-ethoxy-
3-methoxybenzaldehyde (0.5 mL, 3.08 mmol). Yellow crystalline
solid. Yield: 810 mg (81.0%). M.p.: 154 °C. Anal. Calc. for
C
12H17N3O2S: C, 51.9; H, 6.4; N, 15.7; S, 11.9. Found: C, 51.6; H,
6.8; N, 15.5; S, 11.7%. Mass spectrum [m/z (%)]: 268.09(100) [M]+.
IR data (KBr, cmꢁ1): 3508m, 3334m, 3311m
(NH); 1556s
(C@N); 788w
(C@S). 1H NMR data (ppm): 10.49s (1) d(N(2)–H);
plane (12° and 15° in 2b and 9.5° in 2c) shows a more planar ligand
in complexes 2b and 2c than in 1a0.
m
In the supramolecular structure of 2b, dimers are associated by
hydrogen bonds between the N–H thioamide nitrogen group and
the oxygen atom of the ethoxy group of a neighbour dimer
(N(1A)–H(1A2)ꢀꢀꢀO(1A)#1 = 0.86, 2.268, 2.934(7) Å, 134.32°;
#1 = 1 ꢁ x, ½ + y, ½ ꢁ z). This interaction links the units [Re2-
(L2)2(CO)6] in chains running parallel along b axis (Fig. 4C).
m
m
8.52s (1) d(C(2)–H); 8.26s (1) d(N(1)–H); 7.57m (1) d(C(7)–H);
7.05s (1) d(C(6,8)–H); 7.04s (1) d(C(6,8)–H); 4.05m (2) d(O(4)–
R2); 3.84s (3) d(O(5)–R3); 3.14d (3) d(N(1)–R1); 1.34t (3) d(O(4)–
R2).

2874
A. Núñez-Montenegro et al. / Polyhedron 27 (2008) 2867–2876
Fig. 4. Molecular structures (hydrogen atoms are omitted for clarity) and the crystal packing in 2b (A and C) and 2c ꢀ 2(CH3OH) (B and D).
3.2.3. Data for HL3
4-Phenyl-3-thiosemicarbazide (500 mg, 2.99 mmol)/2-ethoxy-
3-methoxybenzaldehyde (0.5 mL, 3.08 mmol). White crystalline
solid. Yield: 771 mg (77.1%). M.p.: 204 °C. Anal. Calc. for
perature after dropwise addition of diethyl ether until saturation.
Yellow solid formed was filtered off and vacuum dried.
3.3.1. Data for 1a (HL1, X = Cl)
C
17H19N3O2S: C, 61.9; H, 5.9; N, 12.7; S, 9.7. Found: C, 61.7; H,
6.0; N, 12.7; S, 9.6%. Mass spectrum [m/z (%)]: 330.09(100) [M]+.
IR data (KBr, cmꢁ1): 3508m, 3333m, 3298m
(NH); 1556s
(C@N); 788w
(C@S). 1H NMR data (ppm): 10.77s (1) d(N(2)–H);
Yield: 227 mg (89.7%). M.p.: 177 °C. Anal. Calc. for
C
14H15ClN3O5SRe: C, 30.1; H, 2.7; N, 7.5; S, 5.7. Found: C, 29.9; H,
m
2.6; N, 7.3; S, 5.4%. Mass spectrum [m/z (%)]: 559 (16.3) [M]+,
524 (100) [MꢁBr]+, 467 (26.3) [Mꢁ2CO]+, 438 (9.7) [Mꢁ3CO]+. IR
m
m
9.88s (1) d(N(1)–H); 8.64s (1) d(C(2)–H); 7.75d (1) d(C(7)–H);
7.73d (2) d(N(1)–R1); 7.36t (2) d(N(1)–R1); 7.19t (1) d(N(1)–R1);
7.06s (1) d(C(6,8)–H); 7.05s (1) d(C(6,8)–H); 4.10m (2) d(O(4)–
R2); 3.88s (3) d(O(5)–R3); 1.36m (3) d(O(4)–R2).
data (KBr, cmꢁ1): 3442m
m(NH); 2027vs, 1922vs, 1903vs m(COfac);
1630vs m(C@N); 757w m
(C@S). 1H NMR data (ppm): 12.49s (1)
d(N(2)–H); 8.78s (1) d(C(2)–H); 8.20s (2) d(N(1)–H); 7.47d (1)
d(C(6)–H); 7.23m (2) d(C(7,8)–H); 4.18m (2) d(O(4)–R2); 3.89s (3)
d(O(5)–R3); 1.27t (3) d(O(4)–R2).
3.3. General synthesis of the complexes [ReX(CO)3(HL)] (1)
3.3.2. Data for 1a0 (HL1, X = Br)
To a solution of the corresponding HL ligand in freshly distilled
chloroform (15 mL) was added the corresponding equimolecular
quantity of fac-[ReX(CO)3(CH3CN)2] (X = Cl, Br). The yellow mixture
was stirred at room temperature for 1 h. The resulting yellow solu-
tion was concentrated in vacuo to ca. 3 mL and stored at room tem-
Yield: 240 mg (88.6%). M.p.: 195–202 °C. Anal. Calc. for
C
14H15BrN3O5SRe: C, 27.8; H, 2.5; N, 6.7; S, 5.3. Found: C, 27.5; H,
2.3; N, 6.1; S, 5.1%. Mass spectrum [m/z (%)]: 603 (19.7) [M]+,
524 (100) [MꢁBr]+, 467 (24.3) [Mꢁ2CO]+, 438 (10.3) [Mꢁ3CO]+.
IR data (KBr, cmꢁ1): 3441m, 3420m
m(NH); 2027vs, 1923vs,

A. Núñez-Montenegro et al. / Polyhedron 27 (2008) 2867–2876
2875
3.3.5. Data for 1c (HL3, X = Cl)
Table 6
Relevant interatomic distances (Å) and angles (°) of [Re2(L2)2(CO)6] (2b) and
[Re2(L3)2(CO)6] ꢀ 2CH3OH (2c ꢀ 2CH3OH)
Yield: 69 mg (34.8%). M.p.: 214 °C. Anal. Calc. for
C
20H19ClN3O5SRe: C, 37.7; H, 3.0; N, 6.6; S, 5.0. Found: C, 37.6; H,
3.0; N, 6.6; S, 5.0%. Mass spectrum [m/z (%)]: 635 (7.4) [M]+, 600
(29.0) [MꢁBr]+, 543 (7.7) [Mꢁ2CO]+. IR data (KBr, cmꢁ1): 3441m
2b
2c ꢀ 2(CH3OH)
Re(1)–N(3A)/N(3)
Re(1)–S(1A)/S(1)
Re(1)–S(1B)/S(1)a
Re(1)–C(103)
Re(1)–C(101)
Re(1)–C(102)
2.191(9)
2.458(3)
2.549(3)
1.903(14)
1.918(12)
1.936(13)
2.213(12)
2.470(3)
2.202(3)
2.4588(8)
2.5467(9)a
1.914(4)
1.917(4)
1.915(4)
m
m
(NH); 2026vs, 1916vs, 1889vs m(COfac); 1555s m(C@N); 743w
(C@S). 1H NMR data (acetone-d6, ppm): 12.56s (1) d(N(2)–H);
10.24s (1) d(N(1)–H); 8.91d (1) d(C(2)–H); 7.48m (5) d(N(1)–R1);
7.38m (1) d(C(6)–H); 7.26m (2) d(C(7,8)–H); 4.18m (2) d(O(4)–
R2); 3.90d (3) d(O(5)–R3); 1.25t (3) d(O(4)–R2).
Re(2)–N(3B)
Re(2)–S(1B)
Re(2)–S(1A)
Re(2)–C(203)
Re(2)–C(202)
Re(2)–C(201)
S(1A)/S(1)–C(1A)/C(1)
C(1A)/C(1)–N(2A)/N(2)
N(2A)/N(2)–N(3A)/N(3)
C(2A)/C(2)–N(3A)/N(3)
S(1B)–C(1B)
2.557(3)
3.3.6. Data for 1c0 (HL3, X = Br)
1.894(14)
1.901(14)
1.921(13)
1.780(11)
1.276(12)
1.384(10)
1.285(11)
1.754(15)
1.311(16)
1.281(14)
1.413(16)
Yield: 177 mg (76.6%). M.p.: 193 °C. Anal. Calc. for
C
20H19BrN3O5SRe: C, 35.4; H, 2.8; N, 6.2; S, 4.7. Found: C, 35.6; H,
2.8; N, 6.1; S, 4.9%. Mass spectrum [m/z (%)]: 679 (11.8) [M]+,
600 (100) [MꢁBr]+, 571 (10.4) [MꢁCO]+, 543 (16.3) [Mꢁ2CO]+,
1.790(3)
1.303(5)
1.403(3)
1.299(5)
514 (14.2) [Mꢁ3CO]+. IR data (KBr, cmꢁ1): 3441m
m
(NH); 2024vs,
1924vs, 1898vs m(COfac); 1565s m(C@N); 740w m
(C@S). 1H NMR
data (ppm): 12.54s (1) d(N(2)–H); 10.20s (1) d(N(1)–H); 8.85d (1)
d(C(2)–H); 7.45m (5) d(N(1)–R1); 7.35m (1) d(C(6)–H); 7.24m (2)
d(C(7,8)–H); 4.15m (2) d(O(4)–R2); 3.86d (3) d(O(5)–R3); 1.21m
(3) d(O(4)–R2).
C(1B)–N(2B)
N(2B)–N(3B)
C(2B)–N(3B)
N(3A)/N(3)–Re(1)–S(1A)/S(1)
N(3A)/N(3)–Re(1)–S(1B)/S(1)a
S(1A)/S(1)–Re(1)–S(1B)/S(1)a
N(3B)–Re(2)–S(1B)
79.0(2)
90.3(2)
82.84(9)
77.5(4)
77.19(7)
83.56(7)a
82.02(3)
a
3.4. General synthesis of complexes [Re2(L)2(CO)6] (2)
N(3B)–Re(2)–S(1A)
90.9(3)
S(1B)–Re(2)–S(1A)
82.43(9)
96.95(9)
96.88(10)
117.8(9)
116.4(9)
115.2(15)
110.2(13)
To a solution of the corresponding adduct fac-[ReBr(CO)3(HL)] 1,
in 15 mL of dry methanol was added the corresponding equimolar
amount of NaOH. The yellow mixture was refluxing for 1 h. The
pale yellow solid formed was filtered out and vacuum dried.
a
Re(1)–S(1A)–Re(2)/Re(1)a
Re(2)–S(1B)–Re(1)
97.98(3)
C(1A)/C(1)–N(2A)/N(2)–N(3A)/N(3)
C(2A)/C(2)–N(3A)/N(3)–N(2A)/N(2)
C(1B)–N(2B)–N(3B)
114.0(3)
116.5(3)
3.4.1. Data for 2a (L1)
C(2B)–N(3B)–N(2B)
Yield: 36 mg (21.1%). M.p.: 215–250 °C. Anal. Calc. for
a
Equivalents atoms generated by symmetry transformations: x + 1, ꢁy + 1,
C
28H28N6O10S2Re2: C, 30.1; H, 2.7; N, 7.5; S, 5.7. Found: C, 29.9;
H, 2.6; N, 7.3; S, 5.4%. Mass spectrum [m/z (%)]: 1046 (39.5) [M]+.
IR data (KBr, cmꢁ1): 3448m,
(NH); 2021vs, 1908vs (COfac);
1737m (C@N); 717w
(C@S). 1H NMR data (ppm): 9.22s (1)
ꢁz + 1.
m
m
1905vs m(COfac); 1624s m(C@N); 757w m
(C@S). 1H NMR data (ppm):
m
m
12.53s (1) d(N(2)–H); 8.72d (1) d(C(2)–H); 8.19s (2) d(N(1)–H);
7.37s (1) d(C(6)–H); 7.21m (2) d(C(7,8)–H); 4.17m (2) d(O(4)–R2);
3.86d (3) d(O(5)–R3); 1.23m (3) d(O(4)–R2).
d(N(1)–H), 8.85s (1) (C(2)–H); 7.78s (1) d(N(1)–H); 7.65s (1)
d(C(6,8)–H); 7.24s (1) d(C(6,8)–H); 7.07s d(C(7)–H); 4.16m (2)
d(O(4)–R2); 3.88s (3) d(O(5)–R3); 1.33t (3) d(O(4)–R2).
This compound was also obtained as 1a0 ꢀ ½C7H8 crystals by
heating a solution of HL1 and [ReBr(CO)5] in toluene for 20 h. Yield:
143 mg (50%).
3.4.2. Data for 2b (L2)
Yield: 64 mg (59.8%). M.p.: 248–253 °C. Anal. Calc. for
C
30H32N6O10S2Re2: C, 33.5; H, 3.0; N, 7.8; S, 5.9. Found: C,
33.3; H, 2.8; N, 7.7; S, 5.6%. Mass spectrum [m/z (%)]: 1074
(9.8) [M]+. IR data (KBr, cmꢁ1): 3443m, 3376m
(NH); 2028vs,
2015vs, 1917vs, 1895vs (COfac); 1714s (C@N); 740w (C@S).
3.3.3. Data for 1b (HL2, X = Cl)
Yield: 162 mg (72.3%). M.p.: 190–202 °C. Anal. Calc. for
m
C
15H17ClN3O5SRe: C, 31.4; H, 3.0; N, 7.3; S, 5.6. Found: C, 31.9; H,
m
m
m
3.2; N, 7.5; S, 5.5%. Mass spectrum [m/z (%)]: 573 (13.0) [M]+,
538 (100) [MꢁBr]+, 481 (21.4) [Mꢁ2CO]+, 453 (8.8) [Mꢁ3CO]+. IR
1H NMR data (ppm): 8.49s (2) d(N(1)–H, C(2)–H); 7.63d (1)
d(C(6,8)–H); 7.14d (1) d(C(6,8)–H); 7.05t d(C(7)–H); 4.15m (2)
d(O(4)–R2); 3.87s (3) d(O(5)–R3); 2.86s (3) d(N(1)–R1); 1.35t (3)
d(O(4)–R2). Single yellow crystals of 2b suitable for X-ray diffrac-
tion were obtained by slow evaporation of a methanol solution
of 1b.
data (KBr, cmꢁ1): 3398m
m(NH); 2023vs, 1899vs m(COfac); 1576s
m
(C@N); 757w m
(C@S). 1H NMR data (ppm): 12.41s (1) d(N(2)–
H); 8.77s (1) d(C(2)–H); 8.17s (1) d(N(1)–H); 7.45d (1) d(C(6)–H);
7.27d (2) d(C(7,8)–H); 7.21m (1) d(C(7,8)–H); 4.18m (2) d(O(4)–
R2); 3.90d (3) d(O(5)–R3); 3.18d (3) d(N(1)–R1); 1.27t (3) d(O(4)–
R2).
3.4.3. Data for 2c (L3)
3.3.4. Data for 1b0 (HL2, X = Br)
Yield: 21 mg (19.5%). M.p.: >250 °C. Anal. Calc. for
C
40H36N6O10S2Re2: C, 40.0; H, 3.0; N, 7.0; S, 5.3. Found: C, 39.9;
H, 2.9; N, 6.9; S, 5.1%. Mass spectrum [m/z (%)]: 1198 (71.4) [M]+.
IR data (KBr, cmꢁ1): 3430m
(NH); 2021vs, 1923vs (COfac);
1707m (C@N); 715w
(C@S). 1H NMR data (ppm): 9.56s (1)
Yield: 219 mg (83.6%). M.p.: 219 °C. Anal. Calc. for
C
15H17BrN3O5SRe: C, 29.2; H, 2.8; N, 6.8; S, 5.2. Found: C, 29.4; H,
2.9; N, 6.7; S, 5.1%. Mass spectrum [m/z (%)]: 617 (10.0) [M]+,
538 (100) [MꢁBr]+, 509 (8.6) [MꢁCO]+, 481 (21.1) [Mꢁ2CO]+, 453
m
m
m
m
(12.6) [Mꢁ3CO]+. IR data (KBr, cmꢁ1): 3445m, 3283m
m
(NH);
d(N(1)–H); 8.87s (1) d(C(2)–H); 7.77d (2) d(C(6,8)–H); 7.46d (1),
7.36t (2), 7.30d (2) d(N(1)–R1); 7.09t (1) d(C(7)–H); 4.24m (1),
4.16m (1) d(O(4)–R2); 3.92s (3) d(O(5)–R3); 1.32t (3) d(O(4)–R2).
Yellow single crystals of 2c ꢀ 2(CH3OH) suitable for X-ray diffrac-
tion were obtained by slow evaporation of a methanol solution
of 1c.
2023vs, 1930vs, 1906vs m(COfac); 1596s m(C@N); 771w m
(C@S). 1H
NMR data (ppm): 12.37s (1) d(N(2)–H); 8.67s (1) d(C(2)–H);
8.14s (1) d(N(1)–H); 7.35s (1) d(C(6)–H); 7.20m (2) d(C(7,8)–H);
4.16m (2) d(O(4)–R2); 3.86d (3) d(O(5)–R3); 3.14t (3) d(N(1)–R1);
1.23m (3) d(O(4)–R2).

2876
A. Núñez-Montenegro et al. / Polyhedron 27 (2008) 2867–2876
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3.5. X-ray data collection, structure determination and refinement
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Crystallographic data were collected on a Bruker SMART CCD-
1000 diffractometer at 293 K using graphite monochromated Mo
Ka radiation (k = 0.71073 Å), and were corrected for Lorentz, polar-
ization and absorption effects [23]. The structures were solved by
direct methods using the program SHELX 97 [24]. All non-hydrogen
atoms were refined with anisotropic thermal parameters. Hydro-
gen atoms were inserted at calculated positions and refined as rid-
ers [24]. Graphics were produced with PLATON [25] and MERCURY [26].
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Chem. 656 (2002) 1.
Acknowledgements
[12] A.G. Quiroga, C. Navarro Ranninger, Coord. Chem. Rev. 248 (2004) 119.
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44 (2005) 834.
This research was supported by the European Rural Develop-
ment Found and The Directorates General for Research of Galician
Government and Spanish Ministry of Education and Science
through projects PGIDIT06PXIB314373PR and CTQ2006-05642/
BQU.
[16] P. Barbazán, R. Carballo, U. Abram, G. Pereiras-Gabián, E.M. Vázquez-López,
Polyhedron 25 (2006) 3343.
Appendix A. Supplementary data
[17] G.J. Palenik, D.F. Rendle, W.S. Carter, Acta Crystallogr., Sect. B 30 (1974) 2390.
[18] G. Thiele, G. Liehr, E. Lindner, Chem. Ber. 107 (1974) 442.
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[20] D.D. Perrin, W.L.F. Armarego, Purification of Laboratory Chemicals, 3rd ed.,
Oxford, 1988.
[21] M.F. Farona, K.F. Kraus, Inorg. Chem. 9 (1970) 1700.
[22] S.P. Schmidt, W.C. Trogler, F. Basolo, Inorg. Synth. 28 (1990) 160.
[23] G.M. Sheldrick, SADABS, University of Göttingen, Germany, 1996.
[24] G.M. Sheldrick, SHELX-97, Program for the Solution and Refinement of Crystal
Structures, v.2, University of Göttingen, Germany, 1997.
[25] A.L. Spek, PLATON, 2002, v. 21.08.03, University of Utrecht, The Netherlands,
2002.
CCDC 683875, 683876, 683877, 683678, 683679 and 683680
contain the supplementary crystallographic data for HL1 ꢀ H2O,
HL2 ꢀ ½H2O, HL3 ꢀ ½C7H8, 2b, 2c ꢀ 2(CH3OH). These data can be ob-
tained free of charge via http://www.ccdc.cam.ac.uk/conts/retriev-
ing.html, or from the Cambridge Crystallographic Data Centre, 12
Union Road, Cambridge CB2 1EZ, UK; fax: (+44) 1223-336-033;
or e-mail: deposit@ccdc.cam.ac.uk.
[26] I.J. Bruno, J.C. Cole, P.R. Edgington, M.K. Kessler, C.F. Macrae, P. McCabe, J.
Pearson, R. Taylor, Acta Crystallogr., Sect. B 58 (2002) 389.
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