ReVN and TcVN complexes with a novel tetradentate hybrid benzamidine/thiosemicarbazone ligand

Article abstract of DOI:10.1016/j.inoche.2012.10.004

N-(diethylthiocarbamoyl)benzimidoyl chloride reacts with o-aminoacetophenone 4-methylthiosemicarbazone under formation of a novel N ₂S₂ benzamidine/thiosemicarbazone ligand (H₂L). The reaction of H₂L with [ReNCl₂(PPh₃) ₂] yields a red complex of the composition [ReN(L)]. The molecular structure of [ReN(L)] reveals a square-pyramidal environment around the Re atom, in which the organic ligand occupies all four positions of the equatorial plane. The reaction of H₂L with [TcNCl₂(PPh ₃)₂] results in a mixture of [TcN(L)] and a side-product of the composition [TcN(PPh₃){Et₂NC(S)NH}(L′)] (L′ = 1,10b-dimethyl-5-phenyl-1,10b-dihydro-[1,2,4]triazolo[1,5-c] quinazoline-2-thiolate). The formation of diethylthiourea and HL′ is the result of a metal-driven decomposition of H₂L followed by cyclization.

Full text of DOI:10.1016/j.inoche.2012.10.004

Inorganic Chemistry Communications 26 (2012) 72–76
Contents lists available at SciVerse ScienceDirect
Inorganic Chemistry Communications
journal homepage: www.elsevier.com/locate/inoche
ReVN and TcVN complexes with a novel tetradentate hybrid benzamidine/
thiosemicarbazone ligand
b
b,
Hung Huy Nguyen a, , Juan Daniel Castillo Gomez , Ulrich Abram
⁎
⁎
a
Department of Chemistry, Hanoi University of Science, 19 Le Thanh Tong, Hanoi, Viet Nam
Freie Universität Berlin, Institute of Chemistry and Biochemistry, Fabeckstr. 34-36, D-14195 Berlin, Germany
b
a r t i c l e i n f o
a b s t r a c t
Article history:
N-(diethylthiocarbamoyl)benzimidoyl chloride reacts with o-aminoacetophenone 4-methylthiosemicarbazone
under formation of a novel N2S2 benzamidine/thiosemicarbazone ligand (H2L). The reaction of H2L with
[ReNCl2(PPh3)2] yields a red complex of the composition [ReN(L)]. The molecular structure of [ReN(L)] reveals
a square-pyramidal environment around the Re atom, in which the organic ligand occupies all four positions
of the equatorial plane. The reaction of H2L with [TcNCl2(PPh3)2] results in a mixture of [TcN(L)] and a
side-product of the composition [TcN(PPh3){Et2NC(S)NH}(L′)] (L′ = 1,10b-dimethyl-5-phenyl-1,10b-
dihydro-[1,2,4]triazolo[1,5-c]quinazoline-2-thiolate). The formation of diethylthiourea and HL′ is the result
of a metal-driven decomposition of H2L followed by cyclization.
Received 28 August 2012
Accepted 3 October 2012
Available online 12 October 2012
Keywords:
Rhenium
Technetium
Thiourea derivatives
Thiosemicarbazones
Cyclization
© 2012 Elsevier B.V. All rights reserved.
X-ray structure
Tri-, tetra- or poly-dentate ligands are of particular interest for
medical or biological applications (including nuclear medical imaging
or therapeutic procedures), since they form stable or kinetically inert
complexes. Previous studies have shown that mono- and bidentate li-
gand systems may suffer from insufficient in vivo stability due to
rapid ligand exchange reactions with plasma components [1–7].
For common technetium(V) and rhenium(V) cores, ligands with ‘me-
dium’ and ‘soft’ donor atoms are particularly recommended [1–9]. Thus,
chelators with a mixed sulfur and nitrogen donor sphere should be very
suitable and some of them have found application in routine nuclear
medical procedures [10–12]. N-[N′,N′-(dialkylamino(thiocarbonyl)]
benzimidoyl chlorides (1) readily react with ammonia or primary
amines under formation of benzamidine-type compounds [13,14].
By the use of thiosemicarbazide in similar reactions, we were recent-
ly successful in the synthesis of a series of tridentate benzamidine/
thiosemicarbazide ligands [15,16]. These novel ligands form stable
complexes with both oxo- and nitridorhenium(V)/technetium(V)
cores [17,18]. Additionally, the organic ligands, their oxorhenium(V)
complexes and their gold(III) complexes show promising cytotoxic-
ity on breast cancer cell lines [18,19].
In a recent communication, we published ReO and TcO complexes
with a novel class of tetradentate thiocarbamoylbenzamidine ligands
derived from o-phenylenediamine (2) [20]. It could be shown that
the chelates are perfectly stable and resist ongoing ligand exchange.
This encouraged us to develop novel tetradentate ligands, which pos-
sess different coordination sites. Such hybrid ligands may provide
more flexibility for the coordination of various metal ions.
Here, we present the synthesis of a tetradentate thiosemicarbazone/
thiocarbamoylbenzamidine hybrid ligand (H2L) and its reactions with
[ReNCl2(PPh3)2] and [TcNCl2(PPh3)2] together with the structures of
their products.
N-(diethylthiocarbamoyl)benzimidoyl chloride 1a readily reacts
with o-aminoacetophenone 4-methylthiosemicarbazone in the pres-
ence of a supporting base like Et3N under formation of the ligand
H2L in high yields. In order to avoid undesired side-reactions, dry
EtOH was used instead of acetone for the preparation of the ligand
H2L [21]. The progress of the reaction can easily be controlled by
thin-layer chromatography, and the ligand H2L precipitates directly
from the reaction mixture as a pure yellow powder (Scheme 1).
The IR spectrum of H2L is characterized by broad bands of the νN\H vi-
brations in the region around 3200 cm−1 and sharp, intense absorptions
at 1717 cm−1 and 1686 cm−1 which are assigned to the νC_N stretches.
The 1H NMR spectrum of the uncoordinated ligand shows three different
N\H resonances at 7.64 ppm, 8.41 ppm and 12.62 ppm. Two sets of well
separated signals corresponding to the resonance of two ethyl groups of
the NEt2 moiety are observed in the 1H NMR spectrum of H2L. This indi-
cates that they are magnetically nonequivalent, which is due to a
hindered rotation around the C-NEt2 bond, which is common for
many uncoordinated thiocarbamoylbenzamidines as well as for
⁎
Corresponding authors.
E-mail addresses: nguyenhunghuy@hus.edu.vn (H.H. Nguyen),
abram@chemie.fu-berlin.de (U. Abram).
1387-7003/$ – see front matter © 2012 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.inoche.2012.10.004

H.H. Nguyen et al. / Inorganic Chemistry Communications 26 (2012) 72–76
73
N
N
NH2
NH2
O
4-methylthio-
semicarbazide
NH
S
S
1a,Et3N,EtOH
N
S
N
HN
HN
HN
HN
H2L
Scheme 1. Synthesis of H2L.
N
N
S
CH2Cl2,Et3N
N
N
N
[ReNCl2(PPh3)2]
+
H2L
Re
-PPh3,HNEt3Cl
S
N
HN
Scheme 2. Reaction of H2L with [ReNCl2(PPh3)2].
their rhenium(V) or technetium(V) complexes [14–19]. In contrast
to this behavior, the C\NHMe bond of the thiosemicarbazone unit
is flexible enough to give only one methyl signal at 3.08 ppm.
H2L readily reacts with [ReNCl2(PPh3)2] in boiling CH2Cl2 under
formation of a red solid of the composition [ReN(L)] [23]. The addi-
tion of a supporting base such as Et3N allows the synthesis to be car-
ried out at ambient temperature with higher yields (Scheme 2). The
product is only sparingly soluble in alcohols, but soluble in CH2Cl2
or CHCl3 and can be recrystallized from a CH2Cl2/MeOH solution.
The IR spectrum of [ReN(L)] reveals a moderate absorption at
3417 cm−1, which is assigned to the νN\H stretch of the MeNH-CS
group. The absorption band of the νC_N vibration is observed as a
very intense peak at 1527 cm−1. This corresponds to a strong
bathochromical shift of about 190 cm−1 and indicates chelate for-
mation with a large degree of π-electron delocalization within the
chelate rings. The 1H NMR spectrum of the compound shows the ab-
sence of N\H resonances of benzamidine and thiocarbazone moie-
ties and a high field shift of the signal corresponding to N\H in the
CS-NHMe residue to 5.28 ppm. This reflects that the organic ligand
is coordinated to Re in the form {L}2−. The hindered rotation around
the C\NEt2 bond results in two magnetically inequivalent ethyl
groups. Thus, two triplet signals of the methyl groups in the \NEt2
residue are observed in the 1H NMR spectrum of [ReN(L)] measured
at room temperature. However, the proton signals of the two meth-
ylene groups, which should consequently be two quartets, appear as
four well separated multiplet resonances at 3.58, 3.68, 4.32 and
4.40 ppm. This pattern of the methylene signals has previously
been rationalized by the rigid structure of the tertiary amine group,
which makes the methylene protons magnetically nonequivalent
with respect to their axial and equatorial positions [24].
A crystallographic study of single crystals of [ReN(L)] shows a
five-coordinate rhenium(V) complex (Fig. 1) [25]. The rhenium atom
has a distorted square-pyramidal environment with the terminal
nitrido ligand in apical position. The ligand {L}2− is equatorially
Table 1
Selected bond lengths (Å) and angles (°) in [ReN(L)] and [TcN(L)].
[ReN(L)]
[TcN(L)]
M–N1
M–S1
M–S12
M–N5
1.668(4)
2.347(1)
2.340(1)
2.054(4)
2.120(4)
105.7(1)
110.3(1)
106.7(2)
100.9(2)
1.617(5)
2.359(1)
2.347(2)
2.057(4)
2.119(4)
105.2(2)
110.3(2)
107.8(2)
101.6(2)
M–N9
N1–M–S1
N1–M–S12
N1–M–N5
N1–M–N9
Fig. 1. Ellipsoid representation of the molecular structure of [ReN(L)] [27].

74
H.H. Nguyen et al. / Inorganic Chemistry Communications 26 (2012) 72–76
N
N
N
N
N
H
N
N
N
CH2Cl2,Et3N
N
N
N
S
S
S
[TcNCl2(PPh3)2] + H2L
Tc
+
Tc
N
-PPh3,HNEt3Cl
PPh3
S
N
HN
main product
side product
Scheme 3. Reaction of H2L with [TcNCl2(PPh3)2].
coordinated via its N2S2 donor set. The Re atom is situated 0.604(1)Å
above the basal plane toward the nitrido ligand. The N1–Re–N/S angles
fall in the range between 100.9(2) and 110.3(1)°. The Re\N1 bond
length of 1.668(4)Å is in the expected range for rhenium–nitrogen tri-
ple bonds [9]. More bond lengths and angles are summarized in Table 1.
The reaction of H2L with the analogous technetium precursor
[TcNCl2(PPh3)2] proceeds in a slightly different way [28]. Besides the
main product [TcN(L)], which can be obtained as large orange-red crys-
tals, an unexpected yellow side-product is formed in moderate yields
(Scheme 3). Both compounds are sparingly soluble in MeOH and crys-
tallize from the reaction mixture after the addition of MeOH as big crys-
tals which can be separated mechanically.
are strongly high-field shifted. Despite the fact that in the 1H NMR spec-
trum of [TcN(L)], the CH3-NH signal of the thiosemicarbazone moiety
appears as a doublet at 3.05 ppm due to coupling with the adjacent
N–H proton, the corresponding resonance of the yellow side-product
is a singlet at 3.66 ppm and another methyl signal appears at
1.41 ppm. This resonance is at an even higher field than that in the spec-
trum of the uncoordinated H2L. From the 1H NMR discussion, we can
conclude that the main skeleton of the organic ligand ‘{L}2− is not
maintained in the side-product. The 31P NMR spectrum reveals a singlet
at 48.86 ppm and, thus, indicates the presence of a PPh3 ligand in the
coordination sphere of the metal.
However, the structure of the compound could not be deduced
unambigously from the spectroscopic methods, and an X-ray diffrac-
tion study was performed also for this complex [32]. Fig. 2 depicts an
ellipsoid presentation of its molecular structure. The structural study
confirms the assumed decomposition of the ligand H2L during the re-
action with the technetium precursor and the formation of a hetero-
cyclic thiol/thione HL′ and N,N-diethylthiourea (see also Scheme 4).
The coordination environment of the technetium atom is best de-
scribed as a distorted square pyramid with an apical nitrido ligand.
The basal plane contains three ligands: the heterocyclic thiolato li-
gand {L′}−, which binds monodentate via its sulfur atom, a bidentate
N,N-diethylthioureido ligand and PPh3, which is arranged in a trans
position to the nitrogen donor atom. The bonding situation in the li-
gand {L′}− reveals the sp2 hybridization of the carbon atoms C11
and C4. Although some delocalization of the π-electron density is
found in the skeleton of {L′}−, the C4–N5 and C11–N10 bond lengths
of 1.32(1)Å and 1.31(1)Å, respectively, are slightly shorter than the
other carbon–nitrogen bonds and indicate more double bond charac-
ter. The Tc–S12 distance of 2.373(2)Å is 0.03 Å shorter than the Tc–S1
bond length. Delocalization of the negative charge is also observed in
the four-membered chelate ring of the N,N-diethylthioureido ligand
and is reflected by the C2–N3 and C2–S1 bond lengths, which fall be-
tween the values of carbon–nitrogen and carbon–sulfur single and
double bonds.
IR and 1H NMR spectra of [TcN(L)] mainly exhibit the same patterns
as described for the rhenium complex described above, indicating a
similar bonding situation. An X-ray diffraction study confirms the anal-
ogous arrangement of the ligands [29]. The technetium atom also re-
veals a distorted square-pyramidal coordination sphere with an apical
{N}3− ligand. Since the molecular structures of [ReN(L)] and [TcN(L)]
are virtually identical, no extra figure of the Tc compound is shown in
this communication. Selected bond lengths and angles of the techne-
tium complex are contained in Table 1 and compared to the values of
the rhenium compound. The atomic labeling scheme of the rhenium
complex has also been applied for the Tc compound. With the reported
structural data, [TcN(L)] resembles the main features of the structures
of the hitherto only two TcVN complexes with tetradentate N2S2 ligands
[30,31].
The IR spectrum of the side-product is quite similar to that of
[ReN(L)], except that the N–H band is sharp and long-wave shifted to
3363 cm−1. However, the 1H NMR spectra of the two compounds are
completely different. In 1H NMR spectrum of the yellow compound,
the ethyl resonances still reflect the rigid structure of the tertiary
amine nitrogen atom of the thiourea group, but the observed signals
The solid state structure of [TcN(PPh3){Et2NC(S)NH}(L′)] contains
relatively large lipophilic voids, which are not filled by solvent mole-
cules and form channel-like structures along the crystallographic c
axis. They are bounded by the phenyl and alkyl residues of the li-
gands, which most probably avoids the stabilization of polar solvent
molecules such as methanol or CH2Cl2 inside these channels.
The formation of [TcN(PPh3){Et2NC(S)NH}(L′)] is reproducible and
clearly a result of the decomposition of H2L. However, it is worth men-
tioning that a similar decomposition is not found in the synthesis of the
analogous rhenium complex, whether under the same conditions, nor
with reflux. More interestingly, the technetium complex [TcN(L)] is
perfectly stable, even under reflux conditions in CH2Cl2 with and with-
out the addition of a base. Additionally, the purity of the ligand H2L was
confirmed by different spectroscopic methods as well as by elemental
analysis. These synthetic evidences suggest that the two technetium
compounds are formed independently and the decomposition of H2L
only occurs during the formation of [TcN(PPh3){Et2NC(S)NH}(L′)].
Fig. 2. Ellipsoid representation of the molecular structure of [TcN(PPh3){Et2NC(S)
NH}(L′)] [27]. Selected bond lengths and angles are summarized in Ref. [33].

H.H. Nguyen et al. / Inorganic Chemistry Communications 26 (2012) 72–76
75
N
+
N
N
N
N
NH
5N
N
Cl-
H
N
N
N
3NH
S
N
S
NH
S
N
NH
Et3N
Et N
3
Cl
PPh3
5
S
Tc
N
Tc
-HNEt3Cl
PPh3
- HNEt3Cl
S
Et2N
+
H
N
N
Cl
PPh3
3
Tc
N
S
4
Scheme 4. Proposed formation of [TcN(PPh3){Et2NC(S)NH}(L′)].
[14] L. Beyer, J. Hartung, R. Widera, Tetrahedron 40 (1984) 405.
[15] H.H. Nguyen, J. Grewe, J. Schroer, B. Kuhn, U. Abram, Inorg. Chem. 47 (2008) 5136.
[16] J. Schroer, U. Abram, Polyhedron 28 (2009) 2277.
[17] H.H. Nguyen, P.I.d.S. Maia, V.M. Deflon, U. Abram, Inorg. Chem. 48 (2009) 25.
[18] H.H. Nguyen, J.J. Jegathesh, P.I.d.S. Maia, V.M. Deflon, R. Gust, S. Bergemann, U.
Abram, Inorg. Chem. 48 (2009) 9356.
[19] P.I.d.S. Maia, H.H. Nguyen, D. Ponader, A. Hagenbach, S. Bergemann, R. Gust, V.M.
Deflon, U. Abram, Inorg. Chem. 51 (2012) 1604.
[20] J.D. Castillo Gomez, H.H. Nguyen, A. Hagenbach, U. Abram, Polyhedron 43 (2012)
123.
[21] Synthesis of 2-aminoacetophenone-N-(4-methylthiosemicarbazone). The compound
was synthesized from 2-aminoacetophenone and 4-methylthiosemicarbazone fol-
A possible mechanism is proposed in Scheme 4. It is supposed that
one of the chlorido ligands of [TcNCl2(PPh3)2] is first exchanged by
the thiourea sulfur atom of H2L. This is confirmed by a previously
published reaction pattern of [ReOCl2(PPh3)3] with a benzamidine
derived from glycine ester, in which an intermediate S-thiourea
monodentate product was successfully isolated [16]. Subsequently, a
phosphine ligand can be replaced either by the N5 or the N3 donor
atoms. The first situation results in the formation of a benzamidine
chelate ring and consequently produces [TcN(L)] (not shown in
Scheme 4). In the second case, an intermediate cationic complex
(3) is formed, in which the positive charge is partially located in the
atom C4. This allows a nucleophilic attack with subsequent bond
cleavage and cyclization. The resulting N,N-diethylthioureido ligand
remains coordinated to the technetium atom and forms the interme-
diate complex 4. The released heterocyclic thion 5 deprotonates and
replaces the chlorido ligand in 4 under formation of the final product
[TcN(PPh3){Et2NC(S)NH}(L′)].
In the present communication, we could show that the novel
benzamidine/thiosemicarbazone hybrid ligand forms stable com-
plexes with technetium and rhenium, but may be only partially suit-
able for applications in nuclear medical labeling procedures, since
during the reactions with common Tc compounds unexpected ligand
cleavage and cyclization reactions may occur. The fact that this be-
havior is not observed with the analogous rhenium compound, puts
a serious question mark over the more or less generally accepted
opinion that model studies with rhenium compounds are sufficient
to predict the behavior of analogous technetium complexes reliably.
lowing
a literature procedure [22]. Yield 70%. Elemental analysis: Calcd. for
C10H14N4S: C, 54.03; H, 6.35; N, 25.20; S, 14.42%. Found: C, 54.20; H, 5.82; N, 24.39;
S, 15.65%; IR (KBr, cm−1): 3237 (w), 2955 (w), 2900 (w), 1605 (vs), 1589 (vs),
1537 (m), 1480 (m), 1267 (s), 1110 (m), 1099 (m), 991 (m), 827 (m), 774 (s), 683
(s). 1H NMR (400 MHz, DMSO-d6, ppm): 2.30 (s, 3H, CH3), 3.00 (s, 3H, NCH3), 6.91
(t, J=7.0 Hz, 1H, C6H4), 7.01 (d, J=7.9 Hz, 1H, C6H4), 7.21 (t, J=7.3 Hz, 1H, C6H4),
7.44 (d, J=6.8 Hz, 1H, C6H4), 8.21 (s, br, 2H, NH), 10.20 (s, 1H, NH).Synthesis of
H2L. Solid N-[(diethylamino)(thiocarbonyl)]benzimidoyl chloride (1.018 g, 4 mmol)
was added to a mixture of 2-aminoacetophenone-N-(4-methylthiosemicarbazone)
(889 mg, 4 mmol) and triethylamine (1.01 g, 10 mmol) in 10 mL of absolute ethanol.
The mixture was stirred for 1 h at 50 °C. Upon cooling, H2L deposited as a yellow crys-
talline solid, which was filtered off, washed with cold MeOH and dried in vacuum.
Yield: 45% (616 mg). Elemental analysis: Calcd. for C22H28N6S2: C, 59.97; H, 6.40; N,
19.07; S, 14.55%. Found: C, 59.45; H, 6.02; N, 19.86; S, 15.02%; IR (KBr, cm−1): 3194
(m), 3051 (w), 2974 (m), 2928 (m), 2827 (w), 1717 (s), 1686 (s), 1608 (m), 1574
(s), 1539 (s), 1419 (s), 1335 (m), 1269 (s), 1246 (s), 1180 (m), 1134 (s), 1084 (m),
1026 (m), 898 (m), 759 (m), 694 (m). 1H NMR (400 MHz, CDCl3, ppm): 1.17
(t, J=7.1 Hz, 3H, CH3), 1.22 (t, J=7.1 Hz, 3H, CH3), 1.86 (s, 3H, CH3), 3.08 (s, 3H,
NCH3), 3.75 (q, J=7.1 Hz, 2H, NCH2), 3.88 (q, J=7.1 Hz, 2H, NCH2), 7.07
(t, J=7.1 Hz, 2H, Ph), 7.13–7.19 (m, 4H, Ph+C6H4), 7.26 (m, 3H, Ph+C6H4), 7.64
(s, 1H, NH), 8.41 (s, 1H, NH), 12.63 (s, 1H, NH). 13C NMR (400 MHz, CDCl3, ppm):
11.99 (CH2CH3), 13.53 (CH2CH3), 15.55 (N_CCH3), 31.40 (NCH3), 44.92 (NCH2),
45.63 (NCH2), 125.45, 126.21, 128.08, 129.03, 129.11, 129.44, 130.49, 132.31,
135.28, 136.67 (aromatic), 145.52 (MeC_N), 159.77 (C_N), 178.36 (C_S), 184.95
(C_S).
[22] D.X. West, A.A. Nassar, F.A. El-Saied, M.I. Ayad, Trans. Met. Chem. 24 (1999) 617.
[23] Synthesis of [ReN(L)]. A mixture of H2L (44 mg, 0.1 mmol), [ReNCl2(PPh3)2] (80 mg,
0.1 mmol) and three drops of Et3N in CH2Cl2 (5 mL) was stirred for 2 h at room tem-
perature. The solvent was removed to dryness and the residue was carefully washed
with MeOH, dried in vacuum and redissolved in a CH2Cl2/MeOH (1:1) mixture. Slow
evaporation of the solvent gave red crystals. Yield 75% (48 mg). Elemental analysis:
Calcd. for C22H26N7S2Re: C, 41.36; H, 4.10; N, 15.35; S, 10.04%. Found: C, 41.11; H,
4.19; N, 14.95; S, 10.13%; IR (KBr, cm−1): 3417 (m), 3050 (w), 2970 (m), 2924
(m), 1527 (vs), 1440 (m), 1342 (s), 1257 (m), 1219 (m), 1149 (w), 1072 (m),
1033 (w), 810 (w), 764 (m), 671 (w). 1H NMR (400 MHz, CDCl3, ppm): 1.32
(t, J=7.2 Hz, 3H, CH3), 1.36 (t, J=7.2 Hz, 3H, CH3), 3.11 (d, J=5.0, 3H, NCH3),
3.13 (s, 3H, N=C-CH3), 3.58 (m, 1H, NCH2), 3.68 (m, 1H, NCH2), 4.32 (m, 1H,
NCH2), 4.40 (m, 1H, NCH2), 5.28 (s, br, NH), 6.78 (d, J=8.0 Hz, 1H, C6H4), 6.93
(t, J=7.6 Hz, 1H, C6H4), 7.00 (t, J=7.7 Hz, 1H, C6H4), 7.10 (m, 3H, Ph), 7.27
(d, J=7.2 Hz, 2H, Ph), 7.75 (d, J=7.9 Hz, 1H, C6H4). FAB+ MS (m/z): 639, 90%,
Appendix A. Supplementary material
Supplementary data to this article can be found online at http://
dx.doi.org/10.1016/j.inoche.2012.10.004.
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integration, Tmin=0.2036, Tmax=0.3541. Structure solution and refinement:
SHELXS-97, SHELXL-97 [26], R1=0.0357, wR2=0.0978, GooF=1.157, CCDC de-
posit number: CCDC-898325.
[26] G.M. Sheldrick, SHELXS-97 and SHELXS-97 — a Programme Package for the
Solution and Refinement of Crystal Structures, University of Göttingen,
Germany, 1997..
[27] K. Brandenburg, H. Putz, Diamond — a Crystal and Molecular Structure Visualisa-
tion Software, , 2005. Bonn, Germany.
[28] Synthesis of [TcN(L)] and [TcN(PPh3){Et2NC(S)NH}(L′)]. Solid [TcNCl2(PPh3)2]
(70 mg, 0.1 mmol) was added to a stirred solution of H2L (44 mg, 0.1 mmol) in
[13] L. Beyer, R. Widera, Tetrahedron Lett. 23 (1982) 1881.

76
H.H. Nguyen et al. / Inorganic Chemistry Communications 26 (2012) 72–76
CH2Cl2 (5 mL). After adding 3 drops of Et3N, the mixture was stirred for addition-
al 15 min at room temperature. This resulted in complete dissolution of
[29] Crystal data for [TcN(L)]: triclinic, space group P(−)1, a=8.577(1), b=10.974(1),
a
c=13.672(1) Å, α=66.82(1), β=80.34(1), γ=78.64(1), V=1154.0(2)Å3, Z=2.
STOE-IPDS, Mo Kα radiation (λ=0.71073 Å), T=200 K, 11967 reflections mea-
sured, 6149 independent, 290 parameters, μ=0.830 mm−1, absorption correction:
none. Structure solution and refinement: SHELXS-97, SHELXL-97 [26], R1=0.0580,
wR2=0.0998, GooF=0.902, CCDC deposit number: CCDC-898326.
[TcNCl2(PPh3)2] and the formation of a red solution. The solvent was removed
under vacuum, and the residue was recrystallized from a CH2Cl2/MeOH mixture
to obtain large orange-red crystals of [TcN(L)] and yellow needles of [TcN(PPh3)
{Et2NC(S)NH}((L′)] which were separated mechanically.Data for [TcN(L)]: Yield
40% (21 mg). Elemental analysis: Calcd. for C22H26N7S2Tc: Tc, 17.9%. Found: Tc,
18.1%; IR (KBr, cm−1): 3418 (m), 3051 (w), 2970 (m), 2924 (m), 1547 (s),
1528 (vs), 1477 (m), 1431 (m), 1357m), 1338 (m), 1261 (m), 1226 (m), 1145
(w), 1091 (w), 1064 (m), 1037 (w), 810 (w), 756 (m), 675 (w). 1H NMR
(400 MHz, CDCl3, ppm): 1.34 (m, 6H, CH3), 2.97 (s, 3H, N_C-CH3), 3.05
(d, J=4.8, 3H, NCH3), 3.54 (m, 1H, NCH2), 3.66 (m, 1H, NCH2), 4.19 (m, 1H,
NCH2), 4.26 (m, 1H, NCH2), 5.15 (s, br, NH), 6.67 (d, J=7.9 Hz, 1H, C6H4), 6.89
(t, J=7.4 Hz, 1H, C6H4), 6.95 (t, J=7.6 Hz, 1H, C6H4), 7.10(m, 3H, Ph), 7.28
(d, J=7.1 Hz, 2H, Ph), 7.66 (d, J=7.9 Hz, 1H, C6H4).Data for [TcN(PPh3)
{Et2NC(S)NH}(L′)]: Yield 14% (12 mg). Elemental analysis: Calcd. for C40H41N7-
PS2Tc: Tc, 12.2%. Found: Tc, 12.4%. IR (KBr, cm−1): 3363 (m), 3044 (w), 2978
(m), 2931 (m), 1558 (vs), 1473 (m), 1434 (m), 1307 (s), 1269 (s), 1238 (s),
1184 (m), 1149 (w), 1095 (m), 1068 (m), 860 (w), 740 (s), 694 (s), 528 (m),
497 (m). 1H NMR (400 MHz, CDCl3, ppm): 0.49 (t, J=7.1 Hz, 3H, CH3), 0.88
(t, J=7.1 Hz, 3H, CH3), 1.41 (s, 3H, N=C\CH3), 2.25 (m, 1H, NCH2), 2.39
(m, 1H, NCH2), 3.12 (m, 2H, NCH2), 3.66 (s, 3H, NCH3), 5.76 (s, br, 1H, NH),
7.32 (m, 17H, Ph), 7.60 (m, 6H, Ph), 8.05 (d, J=7.7 Hz, 1H, Ph). 31P NMR
(400 MHz, CDCl3, ppm): 48.86 (s).
[30] F. Tisato, U. Mazzi, G. Bandoli, G. Cros, M.-H. Darbieu, Y. Coulais, R. Guiraud,
J. Chem. Soc., Dalton Trans. (1991) 1301.
[31] G. Cros, H.B. Tahar, D. de Montauzon, A. Gleizes, Y. Coulais, R. Guiraud, E. Bellande,
R. Pasqualini, Inorg. Chim. Acta 227 (1994) 25.
[32] Crystal data for [TcN(PPh3){Et2NC(S)NH}(L′)]×H2O: triclinic, space group P(−)1,
a=11.622(3), b=13.182(3), c=14.620(4)Å, α=92.45(2), β=92.73(2),
γ=110.76(2), V=2087.5(9) Å3, Z=2. STOE-IPDS, Mo Kα radiation
(λ=0.71073 Å), T=200 K, 21,440 reflections measured, 11,079 independent,
465 parameters, μ=0.522 mm−1, absorption correction: none. Structure solu-
tion and refinement: SHELXS-97, SHELXL-97 [26], R1=0.074, wR2=0.1682,
GooF=0.865, CCDC deposit number: CCDC-898327.
[33] Selected bond lengths and angles in [TcN(PPh3){Et2NC(S)NH}(L′)]: Tc–N1
1.617(8), Tc–S1 2.403(3), Tc–N3 2.097(7), Tc–S12 2.373(2), Tc–P 2.405(2), S1–
C2 1.767, S12–C11 1.742(9), C2–N3 1.32(1), C2–N6 1.33(1), C4–N5 1.33(1),
C4–N9 1.34(1), N10–C11 1.32(1), C11–N13 1.39(1), C7–N13 1.48(1), C7–N9
1.47(1); N1–Tc–S1 111.6(3), N1–Tc–N3 107.1(4), N1–Tc–S12 111.6, N1–Tc–P
94.9(3), N3–Tc–P 156.4(2), S1–Tc–S12 136.2(1).