Electroactive 1,5-benzodiazepines bearing either a tetrathiafulvalene or a ferrocene moiety

Article abstract of DOI:10.1016/j.tet.2013.04.005

The synthesis of a series of electroactive 1,5-benzodiazepines bearing either a ferrocene or tetrathiafulvalene core, acting as the electroactive moiety, is reported. The electron donating ability of these redox active 1,5-benzodiazepines is described tog

Full text of DOI:10.1016/j.tet.2013.04.005

Accepted Manuscript
Electroactive 1,5-benzodiazepines bearing either a tetrathiafulvalene or a ferrocene
moiety
Rachedine Kaoua, Bellara Nedjar-Kolli, Thierry Roisnel, Yann Le Gal, Dominique
Lorcy
PII:
S0040-4020(13)00517-6
10.1016/j.tet.2013.04.005
TET 24205
DOI:
Reference:
To appear in: Tetrahedron
Received Date: 6 February 2013
Revised Date: 19 March 2013
Accepted Date: 1 April 2013
Please cite this article as: Kaoua R, Nedjar-Kolli B, Roisnel T, Le Gal Y, Lorcy D, Electroactive 1,5-
benzodiazepines bearing either a tetrathiafulvalene or a ferrocene moiety, Tetrahedron (2013), doi:
10.1016/j.tet.2013.04.005.
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ACCEPTED MANUSCRIPT
Electroactive 1,5-benzodiazepines bearing either a
tetrathiafulvalene or a ferrocene moiety
b
a
a
a
*
Rachedine Kaoua,a,b,c Bellara Nedjar-Kolli, Thierry Roisnel, Yann Le Gal, Dominique Lorcy
*
a SCR, UMR 6226 CNRS-Université de Rennes 1, Campus de Beaulieu, Bât 10A, 35042 Rennes cedex, France.
b Laboratoire de chimie organique USTHB, 16111 Alger, Algérie. c Institut des Sciences Université Mohamed Akli
Ouelhadj Bouira (UMAOB), 10000 Bouira, Algérie.
H
H
N
N
HN
HN
O
O
R = Me3TTF, Fc
R
R
O
O
O
Me
1

ACCEPTED MANUSCRIPT
Electroactive 1,5-benzodiazepines bearing either a tetrathiafulvalene or a
ferrocene moiety
b
a
a
Rachedine Kaoua,a,b,c Bellara Nedjar-Kolli, Thierry Roisnel, Yann Le Gal, Dominique
*
Lorcy a*
a Sciences Chimiques de Rennes (SCR), UMR 6226 CNRS-Université de Rennes 1, Campus
de Beaulieu, Bât 10A, 35042 Rennes cedex, France. Fax : (+33)-2-23-23-67-38 E-mail :
dominique.lorcy@univ-rennes1.fr
b Laboratoire de chimie organique Université des Sciences et de la Technologie "Houari
Boumédienne"(USTHB), 16111 Alger, Algérie.
c Institut des Sciences Université Mohamed Akli Ouelhadj Bouira (UMAOB), 10000 Bouira, Algérie.
Abstract The synthesis of a series of electroactive 1,5-benzodiazepines bearing either a
ferrocene or tetrathiafulvalene core, acting as the electroactive moiety, is reported. The
electron donating ability of these redox active 1,5-benzodiazepines is described together with
their molecular structures, investigated by X-ray diffraction studies.
Keywords: dehydroacetic acid, tetrathiafulvalene, dihydropyrone, ferrocene, 1,5-
benzodiazepine.
1. Introduction
2

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Benzodiazepines, an important class of N-heterocyclic compounds, exhibit a wide range of
biological and pharmacological activities which have contributed to their use as active
ingredient in numerous drugs.1 Various structures of benzodiazepines have been described
and the 1,5-benzodiazepine scaffold exerts similar biological activity to that of their well
known 1,4-isomers.2 Among the various analytical methods which have been used to detect
these drugs or their metabolites into biological fluids the electrochemical detection is worth
mentioning. This method mainly relies on the reduction of the azomethine bond of the
diazepine ring.3,4 However this imine bond is reduced at quite high potential (Ep = -0.8 V vs
Ag/AgCl).5 Therefore, it would be of interest to graft on the benzodiazepine scaffold an
electroactive moiety which is either easily reduced or oxidized in order to facilitate their
electrochemical detection. For that purpose, two electrophores, the tetrathiafulvalene (TTF)6
and the ferrocene (Fc)7 could be of interest as they both exhibit easily accessible and
reversible oxidation processes. Different strategies have been studied with the aim of forming
the 1,5 benzodiazepine ring. They mainly rely on the condensation reactions of o-
phenylenediamine either with α−β unsaturated carbonyl compounds,8 β-haloketones,9 or
ketones under acid catalysis conditions.10 An efficient synthesis of 1,5-benzodiazepine
bearing a pyronyl side chain in the 2 position has also been described using o-
phenylenediamine, DHA (dehydroacetic acid) and aromatic aldehydes in the presence of
catalytic amount of acid.11 Similarly, tetronic acid is known also to react with o-
phenylenediamine to lead to binucleophilic enaminone intermediate. Subsequent reaction of
this intermediate with various electrophiles represents a versatile access to different
heterocyclic structures, including benzofurodiazepine.12,13,14 Therefore the reaction of o-
phenylenediamine with DHA or tetronic acid in the presence of different aromatic aldehydes
under acid catalysis conditions leads easily to 1,5-benzodiazepine. Thus, we decided to
investigate these approaches for the synthesis of electroactive benzodiazepines using either
3

ACCEPTED MANUSCRIPT
trimethyl-tetrathiafulvalene carboxaldehyde (Me3TTFCHO) or ferrocenecarboxaldehyde
(FcCHO) as the electrophile. Herein, we report the synthesis of a series of redox-active 3,4-
dihydro-1,5-benzodiazepines where the electroactive lead is played by either the TTF moiety
or the Fc core using as starting compounds DHA or tetronic acid. The structural and
electrochemical properties are also reported.
2. Results and discussion
The chemical strategy we used for the synthesis of the electroactive 1,5-benzodiazepines
bearing a DHA moiety and a ferrocene (Fc) or a TTF core is outlined in Scheme 1. It relies on
the reaction of o-phenylenediamine (o-PDA) with DHA in ethanol to afford the imine
structure 1. Subsequent reaction of 1 with ferrocene carboxaldehyde or Me3TTFCHO in the
presence of a catalytic amount of trifluoroacetic acid leads to the formation of the 1,5-
1
benzodiazepine 2 and 3 respectively. H NMR analysis of these derivatives reveals that the
CH2-CH of the seven-membered ring appears as an AMX system with a large anisochrony
consistent with a 1,5-benzodiazepine structure.15 The difference in the chemical shift observed
for these protons in 2 (HA, δ = 2.58 ppm; HM, δ = 4.50 ppm; HX, δ = 5.02 ppm) compared to 3
(HA, δ = 2.85 ppm; HM, δ = 4.17 ppm; HX, δ = 5.35 ppm), and especially to the HM one, can be
infer to the different electron donor character of the TTF compared to the Fc core.
4

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Scheme 1.
NH2
N
OH
O
O
HO
EtOH
NH2
CH3
+
O
NH2
o-PDA
Me
Fe
O
O
Me
DHA
1
CHO
H
N
N
HO
1
CF3CO2H, EtOH, ∆
O
Fe
O
Me
2
Me
Me
CHO
Me
H
S
S
S
S
N
N
HO
Me
S
1
S
CF3CO2H, EtOH, ∆
O
O
Me
3
S
S
Me
Me
The formation of 1,5-benzodiazepine according to this strategy leads usually to a seven-
membered ring with one imine belonging to the ring. However, for the benzodiazepine
bearing a DHA moiety two tautomeric forms, the enamine and the enol, can be written as
depicted in Scheme 2. The chemical shift for the H atom involved in the hydrogen bonding
between the DHA and the benzodiazepine is observed at 15.43 ppm for 2 and 15.33 ppm for 3
which is in accordance with either the enolic form or the enamine one (scheme 2). However,
1H NMR studies carried out on analogous systems indicate the presence of the enamine
structure rather than the enol one.15,16
5

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H
O
H
H
H
N
N
N
N
O
O
R
R
O
O
O
R = Fc, Me3TTF
Me
Me
enamine
enol
Scheme 2. Two tautomeric structures of benzodiazepines 2 and 3.
Single crystals suitable for an X-ray diffraction study were obtained for 2 by recrystallization
in EtOH and for 3 by recrystallization in 1,4-dioxane. Compound 2 bearing a Fc moiety
crystallizes in the monoclinic system, space group P21/c with two independent molecules (A
and B). Compound 3 crystallizes in the triclinic system, space group P-1 with one
independent molecule and two solvent molecules. The molecular structures of these
derivatives are represented in Figure 1 and selected bond lengths are listed in Table 1. Both
molecular structures exhibit similar trends. Unambiguously, these benzodiazepines crystallize
under the enamine tautomeric form (scheme 2) and as the E isomer (Scheme 3) with hydrogen
bonds between the N-H•••O=C (1.870(38) Å mole A and 1.792(36) Å mole B in 2 and
1.829(34)Å in 3).17
H
H
H
H
N
N
N
N
O
O
R
R
O
O
O
R = Fc, Me3TTF
O
Me
Me
Z
E
Scheme 3. Two configurations of the enamine form of benzodiazepines 2 and 3.
It can be observed that the 3,4-dihydro-1,5-benzodiazepine is not planar with the folding of
the seven-membered ring which adopts a boat conformation along the N…N hinge. The bond
lengths of the seven membered ring are of comparable values for 2 and 3 indicating that there
is no influence of the nature of the electroactive moiety. The dihedral angles between the
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ACCEPTED MANUSCRIPT
protons involve in the AMX H1 NMR pattern amounts to 177.9 Å and 64.2 Å for
benzodiazepine 2 mole A while for 3 they amount to 173.1 and 54.9° (Scheme 4). The latter
dihedral angle is slightly smaller in 3 compared to the one observed in 2 probably due to the
steric hindrance generated by the TTF core. Nevertheless, these dihedral angles determined in
1
the solid state by X-ray diffraction studies are in accordance with those determined by H
NMR in solution on benzodiazepine analogues by using the coupling constant and the Karplus
type equation.15 This indicates that in solution and in the solid state the seven membered ring
exhibit similar conformation.
HA
N
HA
N
TTF
Fc
HM
HM
HX
HX
Dihedral angles in 2
Mole A
HM-C-C-HX : 59.43(35) Å
HA-C-C-HX : 176.91(26) Å
Mole B
Dihedral angles in 3
HM-C-C-HX : 54.89(28) Å
HA-C-C-HX : 173.10(21) Å
HM-C-C-HX : 64.19(36) Å
HA-C-C-HX : 177.92(28) Å
Scheme 4.
Concerning the redox moieties, TTF and Fc, the bond lengths and the bond angles are in the
usual range for such molecules and confirm that these compounds 2 and 3 are under the
neutral state.
7

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Fig. 1. Molecular structure of 1,5-benzodiazepines 2 molecule A (top) and 3 (bottom).
Table 1
Selected bond lengths (Å) of the benzodiazepine ring in 2, 3 and 5.
H
a
N
b
C-N (a) N-C (b)
C-C (c)
C-C (d)
C-N €
N-C (f)
f
R
N
H
c
e
d
molecule A of 2
molecule B of 2
compound 3
1.408(7)
1.412(7)
1.405(3)
1.479(4)
1.486(4)
1.475(4)
1.532(5) 1.501(5)
1.517(6) 1.493(5)
1.528(4) 1.501(4)
C=Cd
1.334(5) 1.415(6)
1.323(5) 1.418(6)
1.326(3) 1.418(3)
H
a
N
b
f
R
N
H
c
e
d
molecule A of 5
1.425(4)
1.423(3)
1.504(3)
1.478(3)
1.493(4) 1.356(3)
1.493(4) 1.348(3)
1.347(3) 1.412(3)
1.340(3) 1.410(3)
molecule B of 5
The other approach used to synthetize electroactive 1,5-benzodiazepines is depicted in
Scheme 5 and relies on the reaction of tetronic acid with o-phenylenediamine.12-14 This
reaction affords the 4-(2-aminophenylamino)furan-2(5H)-one 4. In refluxing EtOH, 4 in the
8

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presence of FcCHO or Me3TTFCHO and two drops of trifluoroacetic acid leads to the desired
benzodiazepine 5 and 6 respectively.
H
CHO
N
HN
O
Scheme 5.
Fe
Fe
O
CF3CO2H, EtOH, ∆
NH2
O
EtOH
5
NH2
HN
O
+
O
∆
O
NH2
o-PDA
CF3CO2H, EtOH, ∆
tetronic acid
O
H
S
4
Me
Me
CHO
N
O
HN
O
S
S
S
S
Me
S
Me
6
S
S
Me
Me
The benzodiazepine 5 crystallizes in the triclinic system, space group P-1 with two
independent molecules and two molecules of EtOH. The molecular structure of 5 is depicted
in Figure 2 and selected bond lengths of the diazepine ring are collected in Table 1. Within
this compound the diazepine ring is less distorted compared with compounds 2 and 3, due to
the presence of the fused furanone ring. The C–N bond lengths (Table 1), within this ring are
of comparable values than the one observed for 2 and 3. Both sets of data are consistent with
the presence of an enamine form with an exocyclic "ene" structure for 2 and 3 and an intra
"ene" diazepine ring for 5 as the C–N (e) bond (Table 1) is smaller than the C–N (b) bond.
Intermolecular hydrogen bonds are observed between two neighboring molecules as shown in
Figure 2. This intermolecular hydrogen bonds involve the same N-H atoms of the diazepine
ring either as a donor or as an acceptor of hydrogen bonds with one molecule of EtOH and the
the exocyclic O atom of another molecule 5.
9

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Fig. 2. Molecular structure of 1,5-benzodiazepine 5 showing the hydrogen bonds between
EtOH and the N of 5 and between the N-H and the O=C.
Electrochemical investigations were carried out by cyclic voltammetry and the oxidation
potentials are collected in Table 1 together with the oxidation potentials of the Me3TTFCHO
and FcCHO precursors. The cyclic voltammograms show that the benzodiazepines 3 and 6
containing one TTF core display two reversible monoelectronic processes corresponding to
the reversible oxidation of the TTF to the cation radical species and to the dicationic one
(Fig.3.). Contrariwise, the benzodiazepine substituted by a ferrocene moiety, 2 and 5 display
one reversible monoelectronic oxidation process corresponding to the oxidation of the Fc to
the Fc+ (Fig.3.).
In both families, the ferrocene/benzodiazepines and the
TTF/benzodiazepines one, the presence of the DHA core induces a decrease of the overall
donating ability as the first oxidation potential for 2 and 5 is anodically shifted by 120 mV for
2 and 50 mV for 5 compared with 3 and 6. For all these electroactive benzodiazepines, the
oxidation process is observed at easily accessible oxidation potentials especially for the
TTF/benzodiazepines due to the presence of the electron rich TTF core.
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1,2
2
3
0,8
0,4
0,0
-0,4
-0,8
0,0
0,4
0,8
1,2
E (V vs SCE)
Fig. 3. Cyclic voltammograms of 2 (red) and 3 (blue) in 0.1 M CH2Cl2 -[NBu PF . E in V vs
]
4
6
SCE, v = 100 mVs-1.
Table 2
Oxidation potentials of the benzodiazepines 2, 3, 5 and 6, E in
V vs. SCE, CH2Cl2 0.1 M, Pt working electrode with 0.1 M n-
NBu4PF6 scanning rate100mV/s
compound
E1
E2
∆E mV
0.55
0.43
0.74
0.47
0.28
0.23
0.43
0.27
-
-
-
-
-
2
5
FcCHO
-
Fc
0.81
0.78
0.95
0.80
530
550
520
530
3
6
Me3TTFCHO
Me3TTF
3. Conclusion
In summary, we have developed the synthesis of electroactive 1,5-benzodiazepines using a
simple and compatible approach with the electroactive moiety such as the ferrocene and the
11

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TTF. As evidenced by X-ray diffraction studies, the diazepine rings adopt the enamine form
with intramolecular hydrogen bonds between the N-H of the enamine and the carbonyl of
DHA. All these benzodiazepines exhibit reversible oxidation processes at low oxidation
potentials thanks to the presence of the electrophore TTF or Fc. Further investigations of the
influence of the redox active moiety on the biological activity of these benzodiazepines will
be investigated in due course.
4. Experimental
4.1. General
1
13
H NMR and C NMR spectra were recorded on a Bruker Avance 300 III spectrometer with
tetramethylsilane as internal reference. Chemical shifts are reported in ppm. Mass spectra and
elemental analysis results were performed by the Centre de Mesures Physiques de l'Ouest,
Rennes. Melting points were measured using a Kofler hot stage apparatus and are
-3
uncorrected. Cyclic voltammetry were carried out on a 10 M solution of the compounds in
dichloromethane, containing 0.1 M nBu NPF as supporting electrolyte. Voltammograms
4
6
-1
2
were recorded at 0.1 Vs on a platinum disk electrode (A = 1mm ). The potentials were
measured versus Saturated Calomel Electrode. Me3TTFCHO was prepared according to
published procedure.18 All the reagents were purchased and used without additional
purification.
4.2. Synthesis and characterization
4.2.1. General procedure for the synthesis of 1,5-benzodiazepines (2-3)
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A solution of o-phenylenediamine (1.08 g, 0.01 mol) and DHA (1.68 g, 0.01 mol) in 50 mL of
EtOH was stirred for 3h. The precipitate was filtered, washed with diethyl ether and dried.
Compound 1 was obtained in 90 % yield and used in the next step without further
purification. To a stirred suspension of 1 (0.12 g, 0.5 mmol) in 10 mL of EtOH was added 0.5
mmole of the aldehyde (0.137 g for FcCHO and 0.107 g for Me3TTFCHO) and two drops of
CF3CO2H. The mixture was then refluxed for 6 h and the reaction was monitored by TLC.
The resulting mixture was allowed to stand at room temperature and the precipitate was
filtered and washed with water. The precipitate was dissolved in 30 mL of CH2Cl2 and
washed with water dried over MgSO4. The solvent was evaporated and the residue was
recrystallized in EtOH for 2 and in dioxane for 3.
1
Benzodiazepine 2 was obtained as yellow powder in 74 % yield. Mp = 212 °C; H NMR
(CD3Cl) ∂ (ppm) 2.18(s, 3H, CH3), 2.58(dd, 1H, J=12.4, J=11.4, CH2), 4.13(s, 1H, H-N),
4.16-4.23(m, 4H, Fc), 4.28(s, 5H, Fc), 4.5(dd, 1H, J=12.4, 3.3, CH2), 5.02(dd, 1H, J=11.4,
3.3, CH2), 5.80(s, 1H, CH=C), 6.81-6.93(m, 1H, H-Ar), 6.94-7.07(m, 1H, H-Ar), 7.12-
7.25(m, 2H, H-Ar) 15.43(s, 1H, NH); 13C NMR (CD3Cl) δ 19.9 (C84), 36.6 (C67), 64.2(Cp),
65.2 (C66), 66.3(Cp), 68.2(Cp), 68.6 (Cp), 92.7 (Cp), 96.4 (C77), 107.4 (C79), 121.6 (Ar),
121.8 (Ar), 122.4 (Ar), 126.7 (Ar), 128.4(Ar), 140.1 (C69), 163.2 (C80), 163.7 (C82), 172.9
(C76), 184.8.(C78); UV-vis (CH2Cl2) λ (ε L.mol-1cm-1) : 238 (29910), 322 (11360), 375
(14940) ; HRMS calcd for C25H22N2O3Fe56 M+. 454.09798. Found 454.0977.
1
Benzodiazepine 3 was obtained as brown powder in 67 % yield. Mp = 152 °C; HNMR
(CD3Cl) ∂ (ppm) 1.91 (s, 3H, CH3), 1.93 (s, 3H, CH3), 2.15 (s, 3H, CH3), 2.17(s, 3H, CH3),
2.84(dd, 1H, J=12.2, J=10.9, CH2), 3.88 (s, 1H, NH), 4.17(dd, 1H, J=12.2, 3.4, CH2), 5.35(dd,
1H, J=10.9, 3.4, CH2), 5.79(s, 1H, CH=C), 7.21-7.25(m, 1H, H-Ar), 7.02-7.10 (m, 2H, H-Ar),
7.14-7.18 (m, 1H, H-Ar), 15.33(s, 1H, NH); 13C NMR (CD3Cl) δ 13.3 (CH3TTF), 13.4
13

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(CH3TTF), 13.5 (CH3TTF), 19.2 (C28), 34.6 (C20), 62.7 (C10), 96.1 (C21), 107.1 (C23),
107.3 (C=C TTF), 121.1 (Ar), 121.5 (Ar), 122.6 (Ar), 122.8(C=C TTF), 124.3(C=C TTF),
125.9 (Ar), 128.3 (Ar), 132.9 (C=C TTF), 140.4 (C12), 161.9 (C24), 164.6 (C26), 171.7
(C19), 182.1 (C22); UV-vis (CH2Cl2) λ (ε L.mol-1cm-1) : 240 (23890), 279 (16210), 322
(20150), 368 (15670) ; HRMS calcd for C24H22N2O3S4 M+. 514.05133. Found 514.0513; Anal
calcd for C24H22N2O3S4 C, 56.01; H, 4.31; N, 5.44; S, 24.92 Found: C, 55.89; H, 4.32; N,
5.36; S, 24.80.
4.2.2. General procedure for the synthesis of 1,5-benzodiazepines (5-6)
A solution of o-phenylenediamine (1.08 g, 0.01 mol) and tetronic acid (1 g, 0.01 mol) in 25
mL of EtOH was refluxed for 30 min. The mixture was cooled to room temperature and the
precipitate was filtered recovered by filtration. Compound 4 was recrystallized in EtOH. To a
stirred suspension of 4 (950 mg, 0.5 mmol) in 10 mL of EtOH was added 0.5 mmole of the
aldehyde (0.137 g for FcCHO and 0.107 g for Me3TTFCHO) and two drops of CF3CO2H. The
mixture was then refluxed for 6 h and the reaction was monitored by TLC. The resulting
mixture was allowed to stand at room temperature and the precipitate was filtered and washed
with water. The precipitate was dissolved in 30 mL of CH2Cl2 and washed with water dried
over MgSO4. The solvent was evaporated and the residue was recrystallized in EtOH for 5
and in DMF for 6.
1
Benzodiazepine 5 was obtained as yellow powder in 73 % yield. Mp = 248 °C; H NMR
(DMSO-d6) ∂ (ppm) 3.75 (m, 1H, H-Ferr), 3.88 (m, 1H, H-Ferr), 3.96 (m, 1H, H-Ferr), 4.09
(m, 1H, H-Ferr), 4.11 (s, 5H, H-Ferr), 4.82 (d, 2H, J = 4.9 Hz, CH2), 4.88 (d, J=4.5 Hz, 1H,
CH), 5.78 (d, J=4.9 Hz, 1H, NH), 6.62-6.72(m, 3H, H-Ar), 6.78-6.82(m, 1H, H-Ar), 9.70(s,
1H, NH); 13C NMR (DMSO-d6) δ 52.6 (CH, diazepine), 65.7 (Cp), 66.0 (Cp), 66.1 (Cp), 66.6
(Cp), 67.4 (CH2), 68.4 (Cp), 93.2 (Cp), 98.3 (C=C, diazepine), 119.3(C=C, diazepine), 120.4
14

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(Ar), 122.5 (Ar), 122.7 (Ar), 130.9 (Ar), 138.2 (Ar), 158.6 (Ar), 172.9 (CO2); UV-vis
(CH2Cl2) λ (ε L.mol-1cm-1) : 243 (21300), 307 (7710), 451 (750); HRMS calcd for
C21H18N2O2Fe56 M+. 386.07177. Found 386.0729.
1
Benzodiazepine 6 was obtained as brown powder in 63 % yield. Mp = 278 °C; H NMR
(DMSO-d6) ∂ (ppm) 1.84 (s, 3H, CH3), 1.87 (s, 3H, CH3), 2.15 (s, 3H, CH3), 4.84 (s, 2H,
CH2), 4.98 (d, 1H, J=3.8 Hz, CH), 5.98 (d, 1H, J=3.7 Hz, NH), 6.82-6.94 (m, 4H, H-Ar), 9.91
13
(s, 1H, NH) ; C NMR (DMSO-d6) 13.3 (CH3TTF), 13.4 (CH3TTF), 14.1 (CH3TTF), 51.9
(CH, diazepine), 66.1 (CH2), 95.7 (C=C, diazepine), 113.7 (C=C TTF), 119.8 (C=C,
diazepine), 121.1 (Ar), 122.7 (Ar), 123.4 (Ar), 125.3 (C=C TTF), 130.9 (Ar), 136.7 (Ar),
158.2 (Ar), 172.2 (CO2); UV-vis (DMF) λ (ε L.mol-1cm-1) : 267 (19280), 314 (30270), 467
(530); HRMS calcd for C20H18N2O2S4 M+. . 446.02512 Found . 446.0252. Anal calcd for
C20H18N2O2S4 C, 53.78; H, 4.06; N, 6.27; S, 28.72. Found: C, 53.32; H, 4.09; N, 6.10; S,
28.81.
4.3. Crystallography
Single-crystal diffraction data were collected on APEX II Bruker AXS diffractometer, Mo-Kα
radiation (λ = 0.71073 Å), for compounds 2, 3 and 5 (Centre de Diffractométrie X, Université
de Rennes, France). The structures were solved by direct methods using the SIR97 program19,
and then refined with full-matrix least-square methods based on F2 (SHELX-97)20 with the aid
of the WINGX program.21 All non-hydrogen atoms were refined with anisotropic atomic
displacement parameters. Except nitrogen linked hydrogen atoms that were introduced in the
structural model through Fourier difference maps analysis, H atoms were finally included in
their calculated positions.
15

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Crystal data for 2 (2(C25H22FeN2O3)); M = 908.59. T = 150(2) K; monoclinic P21/c, a =
6.2447(11), b = 27.047(5), c = 23.789(4) Å, β = 95.263(9) °, V = 4001.0(12) Å3, Z = 4, d =
1.508 g.cm-3, ꢀ = 0.785 mm-1. A final refinement on F2 with 9103 unique intensities and 573
parameters converged at ωR(F2) = 0.0964 (R(F) = 0.0492) for 5215 observed reflections with
I > 2σ(I).
Crystal data for 3 (C24 H22 N2 O3 S4, 1.5(C4 H8 O2)); M = 646.83. T = 150(2) K; triclinic P -1,
a = 7.6361(3), b = 11.8253(4), c = 17.0490(6) Å, α = 96.626(2), β = 92.349(2), γ = 99.234(2)
°, V = 1506.63(9) Å3.Z = 2, d = 1.426 g.cm-3, ꢀ = 0.362 mm-1. A final refinement on F2 with
6744 unique intensities and 389 parameters converged at ωR(F2) = 0.1188 (R(F) = 0.0526) for
4826 observed reflections with I > 2σ(I).
Crystal data for 5 (C21H18Fe1N2O2); M = 864.58. T = 150(2) K; triclinic P-1, a = 10.9619(7),
b = 13.7303(9), c = 14.9665(10) Å, α = 83.262(3), β = 73.607(3), γ = 66.771(2) °, V =
1985.8(2) Å3, Z = 2, d = 1.446 g.cm-3, ꢀ = 0.787 mm-1. A final refinement on F2 with 8853
unique intensities and 533 parameters converged at ωR(F2) = 0.0802 (R(F) = 0.0358) for 7242
observed reflections with I > 2σ(I).
5. Supplementary material
Crystallographic data for structural analysis have been deposited with the Cambridge
Crystallographic Data Centre, CCDC n° 922159-922161 for compounds 2, 3 and 5. Copies of
this information may be obtained free of charge from The CCDC, 12 Union road, Cambridge
CB2 1EZ, UK (Fax: +44-1223-336033; e-mail: deposit@ccdc.cam.ac.uk or www:
http://www.ccdc.cam.ac.uk).
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