Crystal structures of triazine-3-thione derivatives by reaction with copper and cobalt salts

Article abstract of DOI:10.1021/ic052009d

The reaction of 5-methoxy-5,6-diphenyl-4,5-dihydro-2H-[1,2,4]triazine-3-thione L¹H₂OCH₃ with copper(II) chloride leads to the formation of an organic molecule L² containing two triazine rings linked by a new S-S bond. A binuclear copper(II) complex, 1, containing L¹ is also isolated. The reaction of L¹H₂OCH₃ with copper(I) chloride yields a hexanuclear cluster of copper(I), 2, in which the copper atoms form a distorted octahedron with the ligand L¹ acting as an NS chelate and sulfur bridge, giving to the copper ion a trigonal geometry by one N and two S atoms. In any reaction of the disulfide L² with metal salts, complexes containing this molecule are isolated. Reactions with copper(I) and copper(II) chloride and nickel(II) and cadmium(II) nitrate produce the S-S bond cleavage, giving complexes containing the triazine L¹ behaving as the NS anion, which show spectroscopic characteristics identical with those formed by reaction with L¹H₂OCH₃. However, the reaction with cobalt(II) nitrate gives a low-spin octahedral cobalt(III) complex, in which an asymmetric rupture of the disulfide L² has been produced, giving an unexpected complex with a new ligand and keeping the S-S bond.

Full text of DOI:10.1021/ic052009d

Inorg. Chem. 2006, 45, 3103−3112
Crystal Structures of Triazine-3-thione Derivatives by Reaction with
Copper and Cobalt Salts
Elena Lo´pez-Torres,*,† Ma Antonia Mendiola,† and Ce´sar J. Pastor‡
Departamento de Qu´ımica Inorga´nica and SerVicio Interdepartamental de InVestigacio´n,
UniVersidad Auto´noma de Madrid, 28049 Madrid, Spain
Received November 21, 2005
The reaction of 5-methoxy-5,6-diphenyl-4,5-dihydro-2H-[1,2,4]triazine-3-thione L1H2OCH3 with copper(II) chloride
leads to the formation of an organic molecule L2 containing two triazine rings linked by a new S
S bond. A
−
binuclear copper(II) complex, 1, containing L1 is also isolated. The reaction of L1H2OCH3 with copper(I) chloride
yields a hexanuclear cluster of copper(I), 2, in which the copper atoms form a distorted octahedron with the ligand
L1 acting as an NS chelate and sulfur bridge, giving to the copper ion a trigonal geometry by one N and two S
atoms. In any reaction of the disulfide L2 with metal salts, complexes containing this molecule are isolated. Reactions
with copper(I) and copper(II) chloride and nickel(II) and cadmium(II) nitrate produce the S−S bond cleavage, giving
complexes containing the triazine L1 behaving as the NS anion, which show spectroscopic characteristics identical
with those formed by reaction with L1H2OCH3. However, the reaction with cobalt(II) nitrate gives a low-spin octahedral
cobalt(III) complex, in which an asymmetric rupture of the disulfide L2 has been produced, giving an unexpected
complex with a new ligand and keeping the S−S bond.
Introduction
the other hand, in some cases reactions with disulfides induce
the reductive disulfide bond cleavage to give thiolate
complexes.9 Interconversion between disulfides RSSR and
the corresponding 2RS- is a very important redox process,
involved in a wide variety of manmade functional materials
and many biological systems,10,11 although factors that control
the biological RSSR/2RS- interconversion are not well
understood.
Current interest in developing the chemistry of multi-
nuclear transition-metal complexes draws inspiration from
two different fields such as chemistry of materials and
bioinorganic chemistry. In several cases, nature has selected
a mixed N/S coordination environment for the metal cofactor,
including blue copper proteins, iron and cobalt nitrile
hydratases, cytidine deaminase, bacteriophage T7 lysozime,
spinach carbonic anhydrase, alcohol dehydrogenase, and
peptide deformylase,12 so synthetic efforts have been applied
A great deal of the chemistry of metal thiolates involves
thiolate as the terminal or bridging ligand. Thiolates can bond
to only one metal,1 bridging between two or three metals, to
give binuclear, linear, or three-dimensional cluster com-
pounds or high polymers, and the bridges can consist of one,
three, or four thiolate S atoms.2-6 S-S bond formation may
occur in thiolate complexes with the reduction of some
external oxidant or the metal, which hampers the synthesis
of complexes with metals in their higher oxidation states.7
Reactions of copper(II) with thiolates usually lead to reduc-
tion with the formation of RSSR and copper(I) species.8 On
* To whom correspondence should be addressed. E-mail: elena.lopez@
uam.es.
† Departamento de Qu´ımica Inorga´nica.
‡ Servicio Interdepartamental de Investigacio´n.
(1) Lo´pez-Torres, E.; Mendiola, M. A.; Rodr´ıguez-Procopio, J.; Sevilla,
M. T.; Colacio, E.; Moreno, J. M.; Sobrados, I. Inorg. Chim. Acta
2001, 323, 130-138.
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Acta 2001, 324, 336-341.
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Chem. 2004, 43, 5222-5230.
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Chemistry II; Elsevier: Amsterdam, The Netherlands, 2004.
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8097.
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London, 1984; Parts 1 and 2.
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F. J.; Lezama, L.; Rojo, T. Eur. J. Inorg. Chem. 2003, 2639-2650.
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10.1021/ic052009d CCC: $33.50
Published on Web 03/07/2006
© 2006 American Chemical Society
Inorganic Chemistry, Vol. 45, No. 7, 2006 3103

Lo´pez-Torres et al.
Chart 1. Drawing of LH2OCH3
toward modeling of the active site of N,S-containing met-
alloproteins. One difficulty in handling alkylthiolate ligands
includes their facile oxidation to disulfide products as well
as their inherent propensity toward forming bridged poly-
nuclear species. The only relatively easy syntheses are those
of the neutral [MIIN2S2] complexes, of which there are several
examples, some of them published by us.1,4,13
In particular, multinuclear CuII complexes have been
receiving considerable attention, and some recent successes
include the synthesis of mixed N,S(alkylthiolate)-CuII
complexes as the first models for blue copper proteins.14,15
The flexibility of the coordination sphere around CuII, in
combination with steric requirements and crystal packing
forces, leads to structural diversity. The growing awareness
of the involvement of cluster compounds at the active sites
of biomolecules such as enzymes is another point of interest
in multinuclear CuII complexes.16,17 The chemistry of the
cluster of CuI with S ligands is extremely important in life
systems, and many technologies also utilize CuI-S clusters.
Yet, the structure types, the bonding, and the cluster redox
properties of CuI-S clusters are rather incompletely under-
stood. It has been determined that yeast and mammalian
metalloproteins (MT), proteins that contain a CuI-S cluster,
function as antioxidants.18 They can also be used as precur-
sors for new functional materials19 and heterogeneous
catalysts.20 There are few copper(I) thiosemicarbazone
complexes structurally characterized, but different structures
have been observed: monomeric, binuclear, tetranuclear, or
hexanuclear clusters.21-23
CuI-CuI bonding interactions have widely been invoked
to be a driving force for the self-assembly of CuI arrange-
ments and to play an important role with regard to the
photoluminescence of polynuclear CuI complexes containing
phosphine or pyridine ligands. Weak but real d10-d10 metal
bonding is well established for second and third transition
series metal complexes but, in the case of CuI, is unre-
solved.24 Although an electron diffraction study on CuO2
found evidence of Cu-Cu bonding,25 several studies on
binuclear CuI complexes have denied the existence of
Cu-Cu bonds.26-28
Reactions of 5-methoxy-5,6-diphenyl-4,5-dihydro-2H-
[1,2,4]triazine-3-thione L1H2OCH3 (Chart 1) with divalent
metal nitrates such as Co, Ni, Zn, Cd, Pb and some organo-
tin(IV) compounds afforded complexes in which the ligand
has lost the inserted OCH3 group acting as a monoanion
L1.29,30 Those complexes are NS chelates, besides in Zn, Cd,
and Pb derivatives the S atom acts as a bridge, giving
binuclear structures. Recently, we have observed different
behavior in reactions with mercury nitrate and methylmercury
chloride.31 In both complexes, L1 acts as monodentate ligand
by the S atom, giving a linear disposition for the Hg atom.
Following our interest in the reactivity of cyclic derivatives
from benzil and thiosemicarbazide with transition-metal salts,
which show variable oxidation states as well as a wide
geometry and coordinative preferences, in this paper we
report the structural characterization of compounds formed
by the reaction of L1H2OCH3 with copper(II) and copper(I)
chlorides and the reactivity of the new organic derivative
L2 with copper chlorides and cobalt(II), nickel(II), and
cadmium(II) nitrates.
Experimental Section
Physical Measurements. Microanalyses were carried out using
a Perkin-Elmer 2400 II CHNS/O elemental analyzer. IR spectra in
the 4000-400-cm-1 range were recorded as KBr pellets on a Jasco
FT/IR-410 spectrophotometer. 1H and 13C NMR spectra were
recorded on Bruker AMX-300 and AMX-500 spectrophotometers
using CDCl3 and DMSO-d6 as solvents and tetramethylsilane as
the reference. Fast atom bombardment (FAB) mass spectra were
recorded on a VG Auto Spec instrument using Cs as the fast atom
and m-nitrobenzyl alcohol (m-NBA) as the matrix. Matrix-assisted
laser desorption ionization time-of-flight (MALDI-TOF) mass
spectra were recorded using a Bruker Reflex III mass spectrometer
equipped with a nitrogen laser emitting at 337 nm, using ditranol
as the matrix. Conductivity data were measured using freshly
prepared N,N-dimethylformamide (DMF) solutions (ca. 10-3 M)
at 25 °C with a Metrohm Herisau model E-518 instrument.
Magnetic susceptibilities of powder samples were measured in the
(13) Calatayud, D. G.; Lo´pez-Torres, E.; Mendiola, M. A.; Pastor, C. J.;
Procopio, J. R. Eur. J. Inorg. Chem. 2005, 21, 4401-4409.
(14) Holland, P. L.; Tolman, W. B. J. Am. Chem. Soc. 1999, 121, 7270-
7271.
(15) Holland, P. L.; Tolman, W. B. J. Am. Chem. Soc. 2000, 122, 6331-
6332.
(16) Karlin, K.-D., Tyeklor, Z., Eds. Bioinorganic Chemistry of Copper;
Chapman and Hall: New York, 1993.
(17) Pal, S.; Barik, A. K.; Gupta, S.; Hazra, A.; Kar, S. K.; Peng, S.-M.;
Lee, G.-H.; Butcher, R. J.; El Fallah, M. S.; Ribas, J. Inorg. Chem.
2005, 44, 3880-3889.
(18) Liu, C. W.; Staples, R. J.; Fackler, J. P. Coord. Chem. ReV. 1998,
174, 147-177.
(19) Arnold, J. Prog. Inorg. Chem. 1995, 43, 353-418.
(20) Chiavelli, R. R.; Pecoraro, T. A.; Halbert, T. R.; Pan, W. H.; Stiefel,
E. J. J. Catal. 1984, 86, 226-230.
(21) Lhuachan, S.; Siripaisarnpupat, S.; Chaichit, N. Eur. J. Inorg. Chem.
2003, 263-267.
(26) Cotton, F. A.; Feng, X.; Matusz, M.; Poli, R. J. Am. Chem. Soc. 1998,
110, 7077-7083.
(22) Cowley, A. R.; Dilworth, J. R.; Donnelly, P. S.; Labisbal, E.; Sousa,
A. J. Am. Chem. Soc. 2002, 124, 5270-5271.
(27) Poblet, J. M.; Be´nard, M. Chem. Commun. 1998, 1179-1180.
(28) Liu, C. W.; Irwin, M. D.; Mohamed, A. A.; Fackler, J. P., Jr. Inorg.
Chim. Acta 2004, 357, 3950-3956 and references cited therein.
(29) Lo´pez-Torres, E.; Mendiola, M. A. Polyhedron 2005, 24, 1435-1444.
(30) Lo´pez-Torres, E.; Mendiola, M. A.; Pastor, C. J.; Procopio, J. R. Eur.
J. Inorg. Chem. 2003, 2711-2717.
(23) Asfield, L. J; Cowley, A. R.; Dilworth, J. R.; Donnelly, P. S. Inorg.
Chem. 2004, 43, 4121-4123.
(24) Che, C.-M.; Mao, Z.; Miskowsky, V. M.; Tse, M.-C.; Chan, C.-K.;
Cheung, K.-K.; Phillips, D. L.; Leung, K.-H. Angew. Chem., Int. Ed.
2000, 39, 4084-4088.
(25) Zuo, J. M.; Kim, M.; O’Keefe, M.; Spence, J. C. H. Nature 1999,
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press.
3104 Inorganic Chemistry, Vol. 45, No. 7, 2006

Crystal Structures of Triazine-3-thione DeriWatiWes
range 2-293 K with a SQUID magnetometer (MPMS, Quantum
Design) in a 1-T external magnetic field.
808 [ν(CS)]. Anal. Calcd for Cu6C90H60N18S6: C, 54.95; H, 3.43;
N, 12.82; S, 9.77. Found: C, 54.63; H, 3.56; N, 13.02; S, 9.81.
All reagents and other solvents were obtained from standard
commercial sources and were used as received. CuCl was synthe-
sized from copper sulfate pentahydrate and sulfur dioxide.
Slow evaporation of a chloroform solution gave single crystals
suitable for X-ray analysis.
The same complex was obtained from the disulfide L2 under
Preparation of 5-Methoxy-5,6-diphenyl-4,5-dihydro-2H-[1,2,4]-
triazine-3-thione, L1H2OCH3.32 Selected spectroscopic data: 1H
NMR (CDCl3, 300 MHz, 25 °C) δ 9.5 (1H, NH, s), 7.6 (2H, Ph,
m), 7.4 (2H, Ph, m), 7.3-7.1 (6H, Ph, m), 6.9 (1H, NH, s), 3.4
(3H, OCH3, s); 13C NMR (CDCl3, 300 MHz, 25 °C) δ 169.7 (CS),
142.4 (CN), 141.7, 129.3, 133.7, 126.5 (Ph), 83.2 (CR4), 50.7
(CH3O); IR (KBr, cm-1) 3184 (s) and 3131 (s) [ν(NH)], 1608 (w)
[ν(CdN)], 1550 (s) [δ(NCS)], 846 (w) [ν(CS)].
Preparation of Bis[5,6-diphenyl-1,2,4-triazine]-3,3′-disulfide,
L2.33 A solution of copper(II) chloride dihydrate (0.23 g, 0.70 mmol)
in methanol (50 mL) was added to a solution of L1H2OCH3 (0.41
g, 1.40 mmol) in methanol (50 mL). The mixture was stirred for 6
h at room temperature. The beige solid formed was filtered off,
washed several times with methanol, and dried in vacuo; yield 45%;
mp 205 °C; FAB+ (m/z) 529 ([C30H20N6S2 + 1]+, 100%); 1H NMR
(300 MHz, CDCl3, 25 °C) δ 7.6-7.2 (Ph, m); 13C NMR (300 MHz,
CDCl3, 25 °C) δ 167.8 (CS), 156.0, 155.3 (CN), 134.9, 134.8, 131.2,
129.9, 129.7, 128.7, 128.5 (Ph); IR (KBr, cm-1) 1599 (w) and 1581
(w) [ν(CdN)], 1480 (s) [δ(NCS)], 866 (w) [ν(CS)]. Anal. Calcd
for C30H20N6S2: C, 68.18; H, 3.79; N, 15.91; S, 12.12. Found: C,
67.82; H, 4.15; N, 15.85; S, 12.07.
several conditions:
To a suspension of 0.052 g (0.10 mmol) of L2 in methanol (20
mL) was added 0.020 g (0.20 mmol) of CuCl under an argon
atmosphere. The mixture was stirred under reflux for 48 h. The
red solution is concentrated until a red solid appears (yield 60%).
For the same conditions but in the presence of 0.004 g (0.10 mmol)
of LiOH‚H2O, the yield was 65%.
Preparation of [Co(L1S)3], 3. A total of 0.020 g (0.064 mmol)
of Co(NO3)2‚6H2O dissolved in ethanol (2 mL) was added over a
suspension of 0.100 g (0.19 mmol) of L2 and 0.010 g (0.19 mmol)
of LiOH‚H2O in the same solvent (10 mL). The mixture was stirred
under reflux for 7 days. Then the dark-green solid was filtered off,
washed with methanol, and vacuum-dried: yield 68%; mp 198 °C;
ΛM (DMF, Ω-1 cm2 mL-1) 4; FAB+ (m/z) 588 ([Co(L1)2 + 1]+,
20%), 620.0 ([Co(L1)(L1S) + 1]+, 25%), 650.9 ([Co(L1S)2]+, 30%),
851.0 ([Co(L1)3 + 1]+, 10%), 883.0 (Co(L1)2(L1S) + 1]+, 29%),
914.9 ([Co(L1)(L1S)2 + 1]+, 24%), 946.9 (Co(L1S)3 + 1]+, 5%);
13C NMR (DMSO-d6, 500 MHz, 25 °C) δ 184.2 (CS), 152.2, 153.2,
154.5 (CN), 135.0, 134.0, 133.6, 132.3, 130.1, 129.8, 128.8 (Ph);
IR (KBr, cm-1) 1598 (w) and 1577 (w) [ν(CdN)], 1508 (s)
[δ(NCS)], 804 [ν(CS)]. µeff
CoC45H30N9S6: C, 57.03; H, 3.17; N, 13.74; S, 20.28. Found: C,
57.25; H, 3.05; N, 13.54; S, 20.49.
) 0 µB. Anal. Calcd for
Slow evaporation of the solid dissolved in toluene gave single
crystals suitable for X-ray diffraction.
Preparation of [Cu(L1)2]2, 1. The red solution obtained after
discarding the disulfide was concentrated until a red solid ap-
peared: yield 40%; mp 215 °C; ΛM (DMF, Ω-1 cm2 mL-1) 11;
MALDI-TOF (m/z) 593.0 ([Cu(L1)2 + 1]+, a.i. 400), 919.0 ([Cu2-
Slow evaporation of a solution of the complex in DMF gave
single crystals suitable for X-ray analysis.
Preparation of [Ni(L1)2]. A total of 0.055 g (0.19 mmol) of
Ni(NO3)2‚6H2O dissolved in methanol (10 mL) was added over a
suspension of 0.10 g (0.19 mmol) of L2 and 0.008 g (0.19 mmol)
of LiOH‚H2O in methanol (25 mL). The mixture was stirred under
reflux for 12 h. Then the brown solid was filtered off, washed with
methanol, and vacuum-dried: yield 32%; ΛM (DMF, Ω-1 cm2
mL-1) 11; MALDI-TOF (m/z) 587.0 ([NiL2 + 1]+, a.i. 1900); IR
(KBr, cm-1) 1600 (w) and 1579 (w) [ν(CdN)], 1485 (s) [δ(NCS)],
and 817 (w) [ν(CS)]. Anal. Calcd for NiC30H20N6S2: C, 61.36; H,
3.41; N, 14.32; S, 10.91. Found: C, 61.03; H, 3.52; N, 14.16; S,
10.87.
1
(L1)3]+, a.i. 800); H NMR (300 MHz, CDCl3, 25 °C) δ 7.7-7.2
(Ph, m); IR (KBr, cm-1) 1599 (w) and 1578 (w) [ν(CdN)], 1484
(s) [δ(NCS)], 819 [ν(CS)]. Anal. Calcd for Cu2C60H40N12S4: C,
60.86; H, 3.38; N, 14.20; S, 10.82. Found: C, 60.82; H, 3.63; N,
14.65; S, 11.07.
A total of 0.052 g (0.1 mmol) of L2 dissolved in methanol (20
mL) was treated with 0.034 g (0.20 mmol) of CuCl2‚2H2O under
several conditions: at room temperature, at room temperature with
lithium hydroxide, under reflux, and under reflux in the presence
of LiOH‚H2O. In all of the reactions, complex 1 was isolated,
although with impurities of L2 and other copper compounds.
Preparation of [Cd(L1)2H2O]2. The synthesis was carried out
following the same procedure as described that above but with 0.058
g (0.19 mmol) of Cd(NO3)2‚4H2O. The yellow solid was filtered
off, washed with methanol, and vacuum-dried: yield 53%; ΛM
(DMF, Ω-1 cm2 mL-1) 5; FAB+ (m/z) 643.0 ([CdL2 + 1]+, 7%),
Preparation of [Cu(L1)]6, 2. A total of 0.200 g (0.67 mmol) of
L1H2OCH3 was dissolved in methanol (30 mL), and 0.066 g (0.67
mmol) of CuCl was added under an argon atmosphere. The yellow
mixture turned to red about 10 min later and was stirred at room
temperature for 12 h. After that, the reddish solid was filtered off,
washed with methanol, and vacuum-dried. The red solution was
concentrated until more red solid was obtained: yield 70%; mp
250 °C (dec); ΛM (DMF, Ω-1 cm2 mL-1) 7; MALDI-TOF (m/z)
657.4 ([Cu2(L1)2 + 1]+, a.i. 1450), 719.2 ([Cu3(L1)2]+, a.i. 1200),
948.1 ([Cu3(L1)3 + 1]+, a.i. 200), 1046.0 ([Cu4(L1)3]+, a.i. 3400),
752.9 ([Cd2L2 - 1]+, 3%), 1017.9 ([Cd2L3]+, 15%); IR (KBr, cm-1
)
1600 (w) and 1573 (w) [ν(CdN)], 1490 (s) [δ(NCS)], 812 (w)
1
[ν(CS)]; H NMR (300 MHz, DMSO-d6, 25 °C) δ 7.3-7.5 (Ph,
m); 13C NMR (300 MHz, DMSO-d6, 25 °C) δ 128.3, 128.5, 128.8,
129.0, 129.6, 130.4, 135.6, 135.8 (Ph), 150.8, 155.1 (CN), 180.7
(CS). Anal. Calcd for C30H22N6S2OCd: C, 54.68; H, 3.34; N, 12.76;
S, 9.72. Found: C, 54.92; H, 3.32; N, 13.05; S, 9.53.
1
1375.0 ([Cu5(L1)4]+, a.i. 2600), 1704.1 ([Cu6(L1)5]+, a.i. 150); H
X-ray Crystallography. Crystals of compounds were mounted
on a glass fiber and transferred to a Bruker SMART 6K CCD area-
detector three-circle diffractometer with a MAC Science Co., Ltd.,
rotating-anode (Cu KR radiation, λ ) 1.541 78 Å) generator
equipped with Goebel mirrors at settings of 50 kV and 110 mA.
X-ray data of L2 and complex 2 were collected at 100 K and those
of complex 3 at 298 K, with a combination of six runs at different
æ and 2θ angles, 3600 frames. The data were collected using 0.3°
wide ω scans and a crystal-to-detector distance of 4.0 cm.
NMR (DMSO-d6, 500 MHz, 25 °C) δ 7.3-7.5 (Ph, m); 13C NMR
(DMSO-d6, 500 MHz, 25 °C) δ 164.6 (CS), 158.5, 153.8 (CN),
135.9, 135.6, 131.2, 130.1, 129.7, 129.4, 128.9, 128.8 (Ph); IR (KBr,
cm-1) 1599 (w) and 1578 (w) [ν(CdN)], 1487 (s) [δ(NCS)], and
(32) Franco, E.; Lo´pez-Torres, E.; Mendiola, M. A.; Sevilla, M. T.
Polyhedron 2000, 19, 441-451.
(33) Blanco, M. A.; Lo´pez-Torres, E.; Mendiola, M. A.; Brunet, E.; Sevilla,
M. T. Tetrahedron 2002, 58, 1525-1531.
Inorganic Chemistry, Vol. 45, No. 7, 2006 3105

Lo´pez-Torres et al.
Scheme 1. Reactions of L1H2OCH3 and L2 with Cu and Co Salts
The substantial redundancy in data allows empirical absorption
corrections (SADABS)34 to be applied using multiple measurements
of symmetry-equivalent reflections (ratio of minimum-to-maximum
apparent transmission: 0.798 554 for the disulfide ligand L2,
0.837 882 for complex 2, and 0.753 359 for complex 3). The unit
cell parameters were obtained by full-matrix least-squares refine-
ments of 4286 reflections for the disulfide ligand, 6977 for complex
2, and 28 079 for complex 3.
The raw intensity data frames were integrated with the SAINT35
program, which also applied corrections for Lorentz and polarization
effects.
The software package SHELXTL/PC, version 6.14, package36 was
used for space group determination, structure solution, and refine-
ment. The space group determination was based on a check of the
Laue symmetry and systematic absences and was confirmed using
the structure solution. The structure was solved by direct methods
(SHELXS-97),37 completed with difference Fourier syntheses, and
refined with full-matrix least squares using SHELXL-97,38 minimiz-
ing ω(Fo2 - Fc2)2. Weighted R factors (Rw) and all goodness of fit
values (S) are based on F 2; conventional R factors (R) are based
on F. All non-H atoms were refined with anisotropic displacement
parameters. All scattering factors and anomalous dispersions factors
are contained in the SHELXTL/PC, version 6.14, program library.
All of the H atoms were localized by electron densities, but only
the H atoms bonded to chloroform in complex 2 were refined. All
of the other H-atom parameters were calculated, and atoms were
constrained as riding atoms, with U isotropic 20% larger than the
corresponding C atoms for the phenyl H atoms. Anisotropic thermal
parameters, H-atom parameters, and structure amplitudes are
available as Supporting Information.
Chart 2. Proposed Structure for Complex 1
new S-S bond. The formation of disulfides by thiol
oxidation is well documented, so the formation of this species
is more probable than the macrocyclic one, as X-ray
diffraction establishes.
CCDC 279180 for L2, 279182 for complex 2, and 279181 for
complex 3 contain the supplementary crystallographic data for
this paper. These data can be obtained free of charge at www.
ccdc.cam.ac.uk/conts/retrieving.html [or from the Cambridge Crys-
tallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ,
U.K.; fax (international) +44-1223/336-033; e-mail deposit@
ccdc.cam.ac.uk].
In this reaction, the CuII complex 1 can also be isolated.
Its analytical data correspond to the empirical formula
C30H20N6S2Cu, so the OCH3 group has also been lost. The
MALDI-TOF spectrum shows a peak at m/z 593.0 corre-
sponding to [Cu(L1)2 + 1]+ and a peak at m/z 919.0
corresponding to [Cu2(L1)3]+, which indicates the presence
of a dinuclear species. Experimental isotropic distribution
shows the same pattern as the theoretical one for both peaks.
Because of the fact that analytical data indicate the absence
of chloride groups, if the complex contains two metal ions,
it must contain four ligands to get the neutrality and one of
them is lost to form a monopositive ion. The way to get a
dinuclear species could be due to the formation of S bridges.
The ligands would act as a bidentate NS and a bidentate NS
and bridge via a S atom, as occurs in the complexes with
other metals, such as Cd, Ni, and Pb,29 giving a penta-
coordinate geometry for the Cu ion (see Chart 2). The redox
reaction in which the disulfide is obtained causes the
formation of CuI, but in the presence of O2, it is again
oxidized to CuII, which forms complex 1, as occurs in other
cases described in the literature.39,40
Results and Discussion
A summary of the studied reactions and the isolated
compounds is presented in Scheme 1.
The reaction of the ligand L1H2OCH3 with CuCl2‚2H2O
leads to the formation of the organic molecule L2, whose
analytical data indicate an empirical formula C15H10N3S.
From these data, it can be deduced that the molecule has
lost the OCH3 group, according to a mechanism previously
published.30 The FAB+ spectrum only shows a peak at 529.1
amu, the double of the empirical formula, corresponding to
the molecular ion [L2 + 1]+. For this molecular mass and
from L1H2OCH3, there are two possibilities: the opening
and subsequent combination of two triazine rings forming a
macrocycle or the formation of two triazines joined by a
On the other hand, the reaction of L1H2OCH3 with CuCl
permits the synthesis of complex 2, with ligand/metal ratio
1:1, where the ligand has lost the OCH3 group and acts as a
monoanion. The MALDI-TOF spectrum of complex 2
(34) Sheldrick, G. M. SADABS, Program for Empirical Absorption
Correction, version 2.03; Universita¨t Go¨ttingen: Go¨ttingen, Germany,
1997-2001.
(35) Sheldrick, G. M. SAINT+NT, SAX Area-Detector Integration Program;
version 6.04; Bruker AXS: Madison, WI, 1997-2001.
(36) Sheldrick, G. M. SHELXTL/PC, version 6.14; Bruker Analytical X-ray
Systems: Madison, WI, 2000.
(37) Sheldrick, G. M. SHELXS-97, Program for Structure Solution. Acta
Crystallogr., Sect. A 1990, 46, 467.
(38) SHELXL-97, Program for Crystal Structure Refinement; Universita¨t
Go¨ttingen: Go¨ttingen, Germany, 1997.
(39) Ferrer, P. E. G.; Williams, A. M.; Castellano, E. C.; Piro, O. E. Z.
Anorg. Allg. Chem. 2002, 628, 1979-1984.
(40) Itoh, S.; Nagagawa, M.; Fukuzumi, S. J. Am. Chem. Soc. 2001, 123,
4087-4088.
3106 Inorganic Chemistry, Vol. 45, No. 7, 2006

Crystal Structures of Triazine-3-thione DeriWatiWes
Figure 1. MALDI-TOF spectrum of complex 2. Inset: isotopic pattern of the peak at 1375.0 amu.
(Figure 1) shows several peaks corresponding to different
fragmentations of the cluster, because of the loss of Cu or
L1, although the peak corresponding to the molecular ion
cannot be observed. Experimental isotropic distribution
shows the same pattern as the theoretical one in every peak.
As the mass spectra have established, reactions between
ligand L1 and CuCl2‚2H2O lead to the formation of the CuII
complex 1, as well as those with L2, although with impurities
of other compounds. Thus, the S-S bond of ligand L2 is
reductively cleaved by the reaction with CuII ions to generate
the bis(thiolate)dicopper(II) complex. This reaction is favored
by the strong CuII-S bond and the disposition of the triazine
rings and phenyl groups in the disulfide, which hinder the
chelate behavior of the ligand, leading to the rupture of the
S-S bond.
the mother liqueur, an organic product was obtained and its
spectroscopic data suggest that the triazine ring remains, but
a OCH3 group is bonded to the C initially joined to the S
atom in L2. Measurements of magnetic susceptibility indicate
that the complex is diamagnetic, which confirms the oxida-
tion of the metal and the existence of a low-spin octahedral
complex. In the FAB+ spectrum of complex 3 (Figure 2), a
great number of peaks, corresponding to the loss of L1, L1S,
S, and/or Co, can be observed. These fragments agree with
a complex formed by three L1S ligands bonded to one CoIII
atom, with the peak at 946.9 amu being the molecular ion
[Co(L1S)3 + 1]+. Experimental isotropic distribution shows
the same pattern as the theoretical one in all of the peaks. In
this case, the rupture of the disulfide L2 is asymmetric,
keeping the S-S bond, which is an unusual behavior for a
disulfide molecule. To the best of our knowledge, this is the
first time that this type of reaction is described. Therefore,
the ligand bonded to the Co ion is L1S. So, with cobalt
nitrate, the complexes obtained from the ligands L1H2OCH3
and L2 are different: with L1H2OCH3, an octahedral
complex of CoIII with the ligand L1 acting as a bidentate NS
is obtained.29
In the reaction of L2 with CuCl, the CuI complex 2 is
isolated as the sole reaction product. The rupture of the ligand
can be explained in the same way as that for CuII. In both
reactions, a symmetric rupture of the disulfide ligand along
the S-S bond has happened.
With cobalt(II) nitrate, the disulfide ligand L2 yields
complex 3, with an empirical formula C45H30N9S6Co. This
formula indicates an important change in the ligand com-
position (C30H20N6S2) and suggests that the CoII ion has been
oxidized to CoIII. Oxidation of CoII salts in the presence of
thiosemicarbazone ligands in ethanol, methanol, and
chloroform is documented.41-43 The possibility of oxidation
increases with the presence of a basic medium. In fact, this
reaction only takes place in the presence of LiOH‚H2O,
which is not necessary in the reactions with Cu salts. From
This behavior differs with Cu salts, perhaps caused by a
less stable Co-S bond together with the favorable octahedral
arrangement for the CoIII complexes. This cleavage leads to
a complex with greater stability, containing five-membered
chelate rings, compared to four-membered ones.
With nickel and cadmium nitrates, two complexes with
formulae [Ni(L1)2] and [Cd(L1)2H2O]2 are isolated. The
formulae and spectroscopic data correspond to those com-
plexes previously isolated from the ligand L1H2OCH3,29 so
a symmetric rupture of the disulfide L2 has occurred, as seen
with Cu salts.
(41) John, R. P.; Sreekanth, A.; Prathapachandra Kurup, M. R.; Mobin, S.
M. Polyhedron 2002, 21, 2515-2521.
(42) Sau, D. K.; Butcher, R. J.; Chaudhuri, S.; Saha, N. Polyhedron 2004,
23, 5-14.
Crystallography. Crystallographic data of the compounds
are summarized in Table 1.
(43) Saha, N. C.; Butcher, R. J.; Chaudhuri, S. Polyhedron 2003, 22, 383-
390.
Inorganic Chemistry, Vol. 45, No. 7, 2006 3107

Lo´pez-Torres et al.
Figure 2. FAB+ spectrum of complex 3. Inset: isotopic pattern of the molecular ion.
Table 1. Crystal Data and Structure Refinement for L2 and Complexes 2 and 3
L2
2
3
formula
fw
C30H20N6S2
528.64
C92H62N18S6Cl6Cu6
2205.90
C45H30N9S6Co
948.07
cryst syst
space group
a/Å
b/Å
c/Å
triclinic
P1h
triclinic
P1h
orthorhombic
Pbca
18.4406(3)
20.4177(3)
23.5628(3)
90
90
90
8871.7(2)
8
1.420
6027
3888
1.028
54959
5.85400(10)
11.5205(3)
19.5150(4)
95.7120(10)
93.817(2)
101.781(2)
1276.88(5)
2
12.8145(3)
14.1021(4)
15.8709(4)
115.896(2)
104.918(2)
95.854(2)
2416.06(11)
1
R/deg
â/deg
γ/deg
V/Å3
Z
Dc/Mg m-3
abs coeff/mm-1
F(000)
1.375
2.144
548
1.042
1.516
4.615
112
0.935
GOF on F 2
reflns collected
independent reflns
final R1, wR2 [I > 2σ(I)]
R indices (all data)
8040
17934
4213 [R(int) ) 0.0359]
0.0626, 0.1716
0.0748, 0.1840
8280 [R(int) ) 0.0476]
0.0464, 0.1080
0.0668, 0.1167
8370 [R(int) ) 0.0451]
0.0455, 0.1206
0.0584, 0.1297
The crystal structure of L2 consists of discrete molecules
of C30H20N6S2. Each unit is formed by two rings of 5,6-
diphenyl-3-thione-1,2,4-triazine linked by a S-S bond
(Figure 3), which agrees with the spectroscopic data but rules
out the structure previously proposed for this ligand.33 The
molecule has a syn conformation with respect to the S-S
bond. The S-S bond distance is 2.043 Å, and the C-S-
S-C torsion angle has a value of 73.58°, which are within
the range expected for this type of compound.44 Bond
distances and angles in both triazine rings are almost identical
(Table 2).
After loss of a methanol molecule, all C-N bond distances
are very similar, which did not occur in the precursor
molecule L1H2OCH3, and have values between single and
double bonds; as occurs with the N-N bond distances,45 the
C-C bond distance is much shorter than that in L1H2OCH3.
These data indicate a strong electronic delocalization in the
triazine rings. The C-S bond distances are closer to the value
accepted for a single bond, as should be expected after the
formation of the S-S bond. The strong electronic delocal-
ization in both triazine rings gives them an aromatic character
so that stabilizes the new disulfide molecule.
Both triazine ligands can be considered planar, with a
maximum deviation of 0.044 Å for C3 and 0.038 Å for C17.
S1 is 0.0084 Å above and S2 0.038 Å below these planes.
The phenyl rings form, with respect to the triazine ligands,
dihedral angles of 60.20° for C4-C9, 30.75° for C10-C15,
35.98° for C19-C24, and 55.88° for C25-C30.
In the triazines, bond distances and angles are close to
120°, which indicates sp2 hybridization. In the ligand
L1H2OCH3, the angle of the C atom with the OCH3 group
has a value of 108.5°, corresponding to sp3 hybridization.
(44) Delgado, E.; Herna´ndez, E.; Mansilla, N.; Zamora, F.; Mart´ınez-Cruz,
(45) Sutton, E. Tables of Interatomic Distances, Configuration in Molecules
and Ions (Supplement); The Chemical Society: London, 1965.
L. F. Inorg. Chim. Acta 1999, 284, 14-19 and references cited therein.
3108 Inorganic Chemistry, Vol. 45, No. 7, 2006

Crystal Structures of Triazine-3-thione DeriWatiWes
Figure 3. Molecular structure of L2. Thermal ellipsoids are shown at 50% probability.
Table 2. Selected Bond Distances and Angles for L2
Table 3. Selected Bond Distances and Angles for Complex 2a
C1-N1
C1-N3
C1-S1
C2-N2
C2-C3
C2-C10
C3-N3
C3-C4
C16-N4
1.326(4)
1.335(4)
1.776(3)
1.331(4)
1.427(4)
1.486(4)
1.328(4)
1.487(4)
1.322(4)
C16-N6
C16-S2
C17-N6
C17-C18
C18-N5
N1-N2
N4-N5
S1-S2
1.340(4)
1.781(3)
1.331(4)
1.419(5)
1.345(4)
1.345(4)
1.336(4)
2.0335(11)
Cu1-N4
Cu1-S1
Cu1-S3
Cu2-N1
Cu2-S2
Cu2-S3#1
Cu3-N7
Cu3-S1#1
Cu3-S2
S1-C1
1.994(3)
C2-C3
1.496(6)
1.478(6)
1.340(5)
1.343(5)
1.342(6)
1.425(6)
1.481(6)
1.482(6)
1.340(5)
1.343(5)
1.332(6)
1.433(6)
1.479(6)
1.324(5)
1.487(6)
1.340(5)
1.345(5)
1.336(5)
2.2360(12)
2.2735(11)
1.977(4)
2.2456(13)
2.2555(11)
1.996(3)
2.2161(11)
2.2487(11)
1.761(4)
2.2161(11)
1.760(4)
1.751(4)
2.2555(11)
1.333(6)
1.341(5)
1.328(6)
C9-C10
C16-N4
C16-N6
C17-N5
C17-C24
C17-C18
C24-C25
C31-N7
C31-N9
C32-N9
C32-C39
C32-C33
C39-N8
C39-C40
N1-N2
S1-Cu3#1
S2-C16
S3-C31
S3-Cu2#1
C1-N3
N1-C1-N3
N1-C1-S1
N3-C1-S1
N2-C2-C3
N2-C2-C10
C3-C2-C10
N3-C3-C2
N3-C3-C4
C2-C3-C4
N4-C16-N6
N4-C16-S2
N6-C16-S2
N6-C17-C18
127.5(3)
120.3(2)
112.0(2)
119.8(3)
115.2(3)
124.9(3)
119.3(3)
116.3(3)
124.5(3)
127.5(3)
119.9(2)
112.6(2)
119.7(3)
N6-C17-C25
C18-C17-C25
N5-C18-C17
N5-C18-C19
C17-C18-C19
C1-N1-N2
116.5(3)
123.7(3)
119.6(3)
114.5(3)
125.9(3)
116.3(3)
120.5(3)
115.9(3)
116.8(3)
120.4(3)
115.6(3)
102.66(11)
102.69(11)
C1-N1
C2-N2
N4-N5
N7-N8
C2-N2-N1
C3-N3-C1
C2-C9
1.421(6)
C16-N4-N5
N4-N5-C18
C17-N6-C16
C1-S1-S2
N4-Cu1-S1
N4-Cu1-S3
S1-Cu1-S3
N1-Cu2-S2
N1-Cu2-S3#1
S2-Cu2-S3#1
N7-Cu3-S1#1
N7-Cu3-S2
S1#1-Cu3-S2
C1-S1-Cu3#1
C1-S1-Cu1
Cu3#1-S1-Cu1
C16-S2-Cu2
C16-S2-Cu3
Cu2-S2-Cu3
C31-S3-Cu2#1
C31-S3-Cu1
Cu2#1-S3-Cu1
N3-C1-N1
129.45(11)
114.41(11)
111.79(4)
125.63(10)
124.15(11)
106.70(4)
125.53(10)
110.94(10)
117.45(4)
104.54(13)
106.23(15)
88.64(4)
107.31(15)
99.01(13)
93.24(4)
106.97(14)
101.98(13)
100.08(4)
123.9(4)
117.7(3)
118.4(3)
119.7(4)
115.1(4)
125.1(4)
117.8(4)
115.5(4)
126.6(4)
N5-C17-C24
N5-C17-C18
C24-C17-C18
N6-C24-C17
N6-C24-C25
C17-C24-C25
N7-C31-N9
N7-C31-S3
N9-C31-S3
N9-C32-C39
N9-C32-C33
C39-C32-C33
N8-C39-C32
N8-C39-C40
C32-C39-C40
N2-N1-C1
119.6(4)
114.4(4)
126.0(4)
119.8(4)
116.0(4)
124.2(4)
122.5(4)
117.3(3)
120.2(3)
118.2(4)
117.0(4)
124.7(4)
119.2(4)
114.7(3)
126.1(4)
117.5(3)
122.3(3)
120.1(3)
119.9(4)
117.4(4)
119.1(3)
121.5(3)
118.9(3)
119.6(4)
117.4(4)
119.0(3)
120.5(3)
120.2(3)
119.5(3)
117.8(3)
C16-S2-S1
The molecules are linked together by π-π interactions
between the phenyl rings, with a distance of 3.613 Å.
The structure of complex 2 contains two molecules of
chloroform. One of them is included in the model, and the
other one is grossly disordered, which could not be modeled
satisfactorily. The contribution from this solvent molecule
was removed from the observed data using SQUEEZE in
the software program PLATON,46 and the atom count from
this CHCl3 is included in the empirical formula. This
procedure has been previously reported for other inorganic
neutral complexes.47
The molecular structure is shown in Figure 4, and selected
bond distances and angles are summarized in Table 3. The
crystal structure consists of hexanuclear units of [CuL1]6,
where the six CuI atoms form a distorted octahedron (Figure
5). The complex is centrosymmetric, with the inversion point
located at the center of the Cu6 octahedron. In the complex,
the CuI ions are three-coordinate by one N and two S atoms
N2-N1-Cu2
C1-N1-Cu2
C2-N2-N1
N3-C1-S1
C1-N3-C9
N1-C1-S1
C16-N4-N5
C16-N4-Cu1
N5-N4-Cu1
C17-N5-N4
C24-N6-C16
N8-N7-C31
N8-N7-Cu3
C31-N7-Cu3
C39-N8-N7
C32-N9-C31
N2-C2-C9
N2-C2-C3
C9-C2-C3
N3-C9-C2
N3-C9-C10
C2-C9-C10
N4-C16-N6
N4-C16-S2
N6-C16-S2
124.3(4)
118.1(3)
117.6(3)
a Symmetry transformations used to generate equivalent atoms: #1, -x
+ 2, -y, -z + 1.
(46) Spek, A. L. PLATON; The University of Utrecht: Utrecht, The
Netherlands, 2004.
(47) Arnanz, A.; Marcos, M.-L.; Moreno, C.; Farrar, F. H.; Lough, A. J.;
Yu, J. O.; Delgado, S.; Gonza´lez-Velasco, J. J. Organomet. Chem.
2004, 689, 3218-3231.
in a trigonal arrangement. There is no formal Cu-Cu
bonding, although metal-metal interactions are clearly
Inorganic Chemistry, Vol. 45, No. 7, 2006 3109

Lo´pez-Torres et al.
Figure 4. Molecular structure of complex 2. Thermal ellipsoids are shown at 50% probability. CHCl3 molecules are omitted for clarity.
distances increase from 1.628 Å in L1H2OCH3 to 1.751,
1.760, and 1.761 Å in complex 2, and there is also a decrease
in the C-N bond lengths. The coordination mode of the
ligand affords six four-membered chelate rings, and the
triazine rings are almost planar. In the complex, owing to
the deprotonation, there is a considerable electronic delo-
calization through the thiosemicarbazone backbone. As a
consequence, all of the C-N bonds have almost the same
length (Table 3), which does not occur in L1H2OCH3 (1.28-
1.459 Å). In the complex, N-N bond distances are inter-
mediate between the theoretical single and double bonds.45
In addition, the N-C-C angles are close to 120°, as would
be expected for sp2 hybridization, while in L1H2OCH3, they
are 108°, corresponding to sp3 hybridization.
There are three types of π-π interactions between the
phenyl rings, with values of 3.445, 3.483, and 3.483 Å. The
Cu‚‚‚Cu distance of 10.038 Å between two adjacent
molecules indicates that there is no intermolecular Cu‚‚‚Cu
interaction.
Figure 5. Cu atom arrangement in complex 2 generated with Mercury
1.4 from the crystal structure.
Selected bond distances and angles of complex 3 are listed
in Table 4. The complex is formed by discrete units of
[Co(L1S)3], where the CoIII ion is hexacoordinate with a N3S3
environment, in a not very distorted octahedral arrangement
(Figure 6), as can be observed in the bond distances and
angles.
present, with Cu‚‚‚Cu distances of 2.8125, 2.9777, and
3.0056 Å. The S atoms are also in an octahedral arrangement,
although it is more distorted than the one of the Cu atoms.
The NS bidentate ligand forms S atom bridges between
two Cu atoms. The ligand upon coordination is evident in
the observed bond lengths in the cluster. The C-S bond
3110 Inorganic Chemistry, Vol. 45, No. 7, 2006

Crystal Structures of Triazine-3-thione DeriWatiWes
Table 4. Selected Bond Distances and Angles for Complex 3
The aromatic rings form, with respect to the triazine rings,
dihedral angles of 34.32° for C3-C8, 54.67° for C10-C15,
138.21° for C18-C23, 128.69° for C25-C30, 134.61° for
C33-C38, and 131.60° for C40-C45.
There are two types of π-π interactions between the
phenyl rings with distances of 3.541 and 3.880 Å.
Co1-N7
Co1-N4
Co1-N1
Co1-S5
Co1-S1
Co1-S3
S1-S2
1.946(2)
1.956(2)
1.973(2)
2.2098(8)
2.2277(9)
2.2327(9)
2.0665(11)
1.732(3)
2.0544(13)
1.731(3)
2.0611(13)
1.339(4)
1.342(4)
1.315(4)
1.429(4)
S6-C31
C1-N3
C1-N1
C2-N3
C2-C9
C9-N2
C16-N4
C16-N6
C17-N6
C17-C24
C24-N5
C39-N9
N1-N2
N4-N5
N7-N8
1.721(3)
1.331(3)
1.340(4)
1.320(4)
1.424(4)
1.317(3)
1.330(4)
1.343(4)
1.329(4)
1.426(4)
1.324(3)
1.312(4)
1.336(3)
1.338(3)
1.338(3)
IR Spectroscopy. The IR spectrum of L1H2OCH3 is
reported in the Experimental Section. The absence of any
band in the 2600-cm-1 region in any complex suggests the
absence of any thiol tautomer.48 In the spectra of the disulfide
L2 and all of the complexes, there are no bands in the 3000-
3300-cm-1 region, which indicates the absence of N-H
bonds. Moreover, bands attributable to the nitrate group in
complex 3 are not observed.49 The absence of these bands
confirms that the ligand acts as a monoanion in all of the
complexes. The band corresponding to the CS moiety is
shifted to lower frequencies, indicating coordination of the
S atom to the metal ion. The presence of two bands
attributable to CdN bonds could indicate the formation of a
new imine group, due to the loss of the OCH3 group of the
ligand L1H2OCH3, although the great electronic delocaliza-
tion in the ring probably leads to there being only one CdN
band and the new band could be due to the hydrazinic CN.
These imine N atoms are noncoordinate to the metal ion.
S2-C1
S3-S4
S4-C16
S5-S6
C31-N9
C31-N7
C32-N8
C32-C39
N7-Co1-N4
N7-Co1-N1
N4-Co1-N1
N7-Co1-S5
N4-Co1-S5
N1-Co1-S5
N7-Co1-S1
N4-Co1-S1
N1-Co1-S1
S5-Co1-S1
N7-Co1-S3
N4-Co1-S3
N1-Co1-S3
S5-Co1-S3
S1-Co1-S3
S2-S1-Co1
C1-S2-S1
S4-S3-Co1
C16-S4-S3
S6-S5-Co1
C31-S6-S5
N3-C1-N1
N3-C1-S2
N1-C1-S2
N3-C2-C9
N3-C2-C3
C9-C2-C3
N2-C9-C2
N2-C9-C10
C2-C9-C10
N4-C16-N6
N4-C16-S4
91.41(10)
90.95(9)
91.10(9)
91.68(7)
91.89(7)
175.97(7)
93.64(7)
174.59(7)
90.75(7)
86.04(3)
174.91(7)
91.40(7)
93.24(7)
83.99(3)
83.42(4)
100.49(4)
102.34(10)
100.84(4)
102.71(12)
101.26(4)
102.50(11)
124.5(2)
114.4(2)
121.0(2)
118.9(2)
115.9(3)
125.1(3)
120.2(2)
115.0(2)
124.8(2)
124.1(3)
121.4(2)
N6-C16-S4
N6-C17-C24
N6-C17-C18
C24-C17-C18
N5-C24-C17
N5-C24-C25
C17-C24-C25
N9-C31-N7
N9-C31-S6
N7-C31-S6
N8-C32-C39
N8-C32-C33
C39-C32-C33
N9-C39-C32
N9-C39-C40
C32-C39-C40
N2-N1-C1
114.5(2)
118.9(3)
115.3(3)
125.8(3)
119.8(3)
114.2(3)
125.9(2)
123.9(3)
115.1(2)
121.0(2)
120.0(3)
114.1(3)
125.9(3)
119.6(3)
117.7(3)
122.7(3)
118.2(2)
119.18(17)
122.34(18)
119.7(2)
117.4(2)
118.7(2)
122.85(19)
118.29(18)
120.4(2)
117.9(3)
118.8(2)
117.55(17)
123.1(2)
120.0(2)
117.8(3)
NMR Spectroscopy. The NMR assignments for L1H2-
OCH3 and its derivatives are listed in the Experimental
N2-N1-Co1
C1-N1-Co1
C9-N2-N1
1
Section. The H NMR spectra of the ligand L2 and all of
the complexes only show a multiplet in the aromatic region,
corresponding to the phenyl rings of the ligand. The absence
of any signal corresponding to amine protons supports the
ligand deprotonation. The absence of the singlet attributable
to the OCH3 group at 3.4 ppm confirms the loss of the
inserted OCH3 group and the formation of a new CdN bond.
In all of the 13C NMR spectra, the signals corresponding
to the OCH3 group and the tetrasubstituted C atom have
disappeared and a new signal corresponding to an imine
group is observed. In the spectra of all of these complexes,
it can be observed that the imine groups are not bonded to
the metal ion, as the X-ray diffraction has established, and
that the signal corresponding to the thione group is deshield-
ed, suggesting the presence of metal-S bonds.
The 13C NMR spectrum of complex 3 shows one signal
corresponding to CS groups, three to CN, and seven to
aromatic C atoms. Two isomers of octahedral complexes with
asymmetric chelating ligands are possible. In the fac isomer,
the A end of each ligand is trans to a B end, and the three
ligands are equivalent. In the mer form, which has a triple
statistical probability, two of the A ends are trans to each
other, and all three ligands are chemically distinct.50 Thus,
if there is an isomer mixture, four sets of C resonances must
be observed, while if only the fac isomer is present, we would
C2-N3-C1
C16-N4-N5
C16-N4-Co1
N5-N4-Co1
C24-N5-N4
C17-N6-C16
N8-N7-C31
N8-N7-Co1
C31-N7-Co1
C32-N8-N7
C39-N9-C31
Of the two possible isomers, the complex shows a fac
disposition, with the N atoms in front of the S atoms. The
aromatic rings are placed toward the same place, as occurs
with the S atoms. The S atoms bonded to the Co ion are in
the corners of a 3-Å-sided triangle. The complex presents a
basket-type shape.
In the ligand, there is a S-S bond, as occurs in the free
ligand L2, although in the complex, these distances are
slightly longer than those in L2. The coordination mode of
the ligand affords three five-membered chelate rings. Bond
distances and angles in the triazine rings are very similar
and indicate a great electronic delocalization, which is
reflected in the similar values found in the C-N bond
distances. Moreover, they can be considered planar with
maximum deviations of 0.055 Å for C2, 0.022 Å for N4,
and 0.002 Å for N8.
(48) Fenton, D. E.; Cook, D. H.; Nowell, I. W. J. Chem. Soc., Chem.
Commun. 1977, 274-275.
(49) Nakamoto, K. Infrared and Raman Spectra of Inorganic and Coor-
dination Compounds, 5th ed.; Wiley: New York, 1997.
(50) Ebsworth, E. A. V., Rankin, D. W. H., Cradock, S., Eds. Structural
Methods in Inorganic Chemistry; Blackwell Scientific Publications:
Oxford, U.K., 1987.
The C-S bond distances are closer to the value expected
for a single bond and are shorter than those in L2, and the
S-S ones are similar to those found in other compounds
described in the literature.9,39
Inorganic Chemistry, Vol. 45, No. 7, 2006 3111

Lo´pez-Torres et al.
Figure 6. Molecular structure of complex 3. Thermal ellipsoids are shown at 50% probability. H atoms are omitted for clarity.
only see one set, as is observed, so we can establish that we
have the fac isomer.
In every complex, L1 and L1S act as NS bidentate ligands,
giving four- and five-membered chelate rings, respectively.
The structure of the complexes is determined by the structural
preferences of the metal ions, as well as by the ligand
configuration. Complex 1 consists of binuclear species, in
which the S atom of two thiosemicarbazone ligands acts as
a bridge between the Cu ions. Complex 2 is a hexanuclear
cluster where each CuI ion is bonded to one N and two S
atoms in trigonal geometry. Complex 3 is a monomeric
structure where the CoII ion has been oxidized to CoIII. The
metal octahedral N3S3 arrangement is formed by three
unexpected L1S ligands. In this case, the complexes obtained
from L1H2OCH3 and L2 are different.
Conclusions
The reaction of L1H2OCH3 with copper(II) chloride leads
to the formation of the organic molecule L2 containing a
S-S bond linking two triazine units, as well as a CuII
complex containing L1 acting as an anion. However, in the
reaction with copper(I) chloride, a hexanuclear CuI complex
is obtained. The different results are related to the facile
oxidation of L1H2OCH3 in the presence of CuII, whereas
this reaction is not possible with CuI.
We have studied the reactivity of the new disulfide with
copper chlorides and some nitrates such as cobalt(II), nickel-
(II), and cadmium(II). In any reaction, complexes containing
L2 are obtained, probably because of the important steric
requirements of the two triazine and four phenyl rings acting
as chelate ligands. Reactions with CuI, CuII, NiII, and CdII
give complexes in which the S-S bond has disappeared and
where the ligand is L1 acting as in those complexes prepared
from L1H2OCH3. The reaction with CoII leads to a CoIII
complex in which the disulfide has suffered an asymmetric
rupture along a C-S bond while keeping the S-S bond,
with this being the first time that this behavior is described;
therefore, L1S is the ligand coordinated to the Co atom.
Acknowledgment. We thank Prof. Regino Sa´ez and Dr.
Julio Romero of Universidad Complutense de Madrid for
the magnetic susceptibility measurements. We also thank
DGICYT for financial support (Project CT2005-07788/
BQU).
Supporting Information Available: X-ray crystallographic data
(CIF). This material is available free of charge via the Internet at
http://pubs.acs.org.
IC052009D
3112 Inorganic Chemistry, Vol. 45, No. 7, 2006