Interaction of dichloride iron(II) clathrochelate with dimercaptomaleodinitrile: Synthesis of the precursor monoribbed-functionalized phthalocyaninoclathrochelates and the unexpected formation of a new thiophene-containing heterocyclic system in the ribbed chelate fragment of the clathrochelate framework

Article abstract of DOI:10.1021/ic701452g

Clathrochelate iron(II) FeBd₂(S₂C₂(CN) ₂Gm)(BF)₂ tris-dioximate with a ribbed wodinitrile fragment was synthesized as a precursor of the monoribbed-functionalized hybrid phthalocyaninoclathrochelates by nucleophilic substitution of the vic-dichloride FeBd₂(Cl₂Gm)(BF)₂ clathrochelate (1) with the potassium salt of dimercaptomaleodinitrile. Reaction of nitromethane with this salt was followed by the condensation of the reaction products with 1 to yield the clathrochelate with an annulated previously unknown thiazinothiophene heterocyclic system in the ribbed fragment. Both complexes were characterized on the basis of elemental analysis; MALDI-TOF mass spectrometry; IR, UV-vis, ⁵⁷Fe Moessbauer, and NMR spectroscopies; and X-ray crystallography.

Full text of DOI:10.1021/ic701452g

Inorg. Chem. 2008, 47, 2155-2161
Interaction of Dichloride Iron(II) Clathrochelate with
Dimercaptomaleodinitrile: Synthesis of the Precursor
Monoribbed-Functionalized Phthalocyaninoclathrochelates and the
Unexpected Formation of a New Thiophene-Containing Heterocyclic
System in the Ribbed Chelate Fragment of the Clathrochelate
Framework
Yan Z. Voloshin,*,† Oleg A. Varzatskii,‡ Alexander S. Belov,† Zoya A. Starikova,†
Kyrill Y. Suponitsky,† Valentin V. Novikov,† and Yurii N. Bubnov†
NesmeyanoV Institute of Organoelement Compounds, 119991, Moscow, Russia, and Vernadskii
Institute of General and Inorganic Chemistry, KieV-142, 03680, Ukraine
Received July 22, 2007
Clathrochelate iron(II) FeBd2(S2C2(CN)2Gm)(BF)2 tris-dioximate with a ribbed vic-dinitrile fragment was synthesized
as a precursor of the monoribbed-functionalized hybrid phthalocyaninoclathrochelates by nucleophilic substitution
of the vic-dichloride FeBd2(Cl2Gm)(BF)2 clathrochelate (1) with the potassium salt of dimercaptomaleodinitrile. Reaction
of nitromethane with this salt was followed by the condensation of the reaction products with 1 to yield the
clathrochelate with an annulated previously unknown thiazinothiophene heterocyclic system in the ribbed fragment.
Both complexes were characterized on the basis of elemental analysis; MALDI-TOF mass spectrometry; IR, UV–vis,
57Fe Mössbauer, and NMR spectroscopies; and X-ray crystallography.
Introduction
the case of polyenic clathrochelate complexes (i.e., three-
dimensional complexes with the encapsulated metal ion
coordinating five or more nitrogen and/or sulfur donor atoms
of not less than three macrocyclic fragments of an encap-
sulating ligand11), the rigid macrobicyclic framework of
metal tris-dioximates, tris-oximehydrazonates, and tris-azi-
neoximates allows one to fine-tune the spatial positions of
the substituents at this framework, the parts, and the
fragments of clathrochelate molecules. These features make
such systems especially attractive for the design of highly
integrated molecular logic gates.
Molecular electronics aims at designing molecular struc-
tures exhibiting a variety of physical characteristics. This
allows for the creation of devices that convert electron and
energy transfer processes into a logic function of electrical
signals. Controlling the direction of the current or the
localization of the charges in a molecular assembly in
response to one or several input signals results in the
development of a new concept of logic gates at the molecular
level. The characteristics of polynuclear metal complexes
determine their great potential in molecular logic devices:
metal ion centers are sensitive to photoexcitation as well as
to changes in the pH and electrochemical potential.1–10 In
Logic cells of this type can be constructed on the basis of
polynuclear clathrochelates, which are the derivatives of
ribbed-functionalized clathrochelates. The substituents in
* To whom correspondence should be addressed. E-mail: voloshin@
ineos.ac.ru.
(6) de Silv, A. P.; McClenaghan, N. D. Chem.sEur. J. 2004, 10, 574.
(7) de Silva, A. P. Nat. Mater. 2005, 4, 15.
(8) Ellenbogan, J. C.; Love, J. C. Proc. IEEE 2000, 88, 386.
(9) Lent, C. S.; Isaksen, B.; Lieberman, M. J. Am. Chem. Soc. 2003, 125,
1056.
(10) Jiao, J.; Long, G. J.; Rebbouh, L.; Grandjean, F.; Beatty, A. M.;
Fehlner, T. P. J. Am. Chem. Soc. 2005, 127, 17819.
(11) Voloshin, Y. Z.; Kostromina, N. A.; Krämer, R. Clathrochelates:
Synthesis, Structure, and Properties; Elsevier: Amsterdam, 2002.
†
Nesmeyanov Institute.
Vernadskii Institute.
‡
(1) Low, P. J. Dalton Trans. 2005, 2821.
(2) Braun-Sand, S. B.; Wiest, O. J. Phys. Chem. B 2003, 107, 9624.
(3) Lau, V. C.; Berben, L. A.; Long, J. R. J. Am. Chem. Soc. 2003, 124,
9042.
(4) Raymo, F. M. AdV. Mater. 2002, 14, 401.
(5) Balzani, V.; Credi, A.; Venturi, M. Chem. Phys. Chem. 2003, 4, 49.
10.1021/ic701452g CCC: $40.75
Published on Web 01/17/2008
2008 American Chemical Society
Inorganic Chemistry, Vol. 47, No. 6, 2008 2155

Voloshin et al.
Table 1. Crystallographic Data and Experimental Details for Clathrochelates 2 and 3
2
3
empirical formula
fw
C34H20B2F2FeN8O6S2 ·2.5C6H6
1011.44
C35H21B2F2FeN9O8S2 ·2.5C3H6O·0.5n-C7H16
1070.49
temp (K)
color, habit
cryst dimens (mm3)
cryst syst
space group
a (Å)
120
100
dark orange, plate
0.25 × 0.20 × 0.05
triclinic
dark red, plate
0.20 × 0.15 × 0.05
triclinic
j
j
P1
P1
11.876(2)
16.576(3)
26.185(5)
89.197(6)
76.916(5)
69.042(4)
4676(2)
11.931(1)
11.972(1)
19.233(2)
80.312(2)
80.917(2)
68.869(2)
2511.7(4)
2
b (Å)
c (Å)
R (deg)
ꢀ (deg)
γ (deg)
V (Å3)
Z
4
Dcal (g cm-3
F(000)
)
1.437
2076
4.80
1.415
1106
4.57
µ (mm-1
)
min/max transmn coeff
2θmax (deg)
reflns collected
0.813/0.976
52.00
28 224
0.892/0.977
54.00
25 811
indep reflns (Rint
)
18 049 (0.0716)
1105
0.0712 (5827 reflns)
0.0996
10 785 (0.0722)
690
0.0689 (6598 reflns)
0.1575
refined params
a
R1 [I > 2σ(I)]
b
Rw (all data)
GOFc
0.961
1.038
max/min residual peak
R1 ) (∑||Fo| - |Fc||)/∑|Fo|. Rw ) [∑(w(Fo - Fc )2)/∑w(Fo )2]1/2
0.459 and –0.383
1.325 and –0.629
GOF ) [∑(w(Fo - Fc )2)/(Nobsd - Nparam)]1/2
. .
a
b
c
2
2
2
2
2
chelate (ribbed) fragments of polyenic clathrochelates have
substantial steric and electronic effects on the polyhedron
geometry and central metal ion properties due to the direct
interaction of the highly conjugated π-system of a ligand
and the π- and σ-systems of the ribbed substituents. One
has an opportunity to use such substituents to change the
encapsulated metal ion properties and to affect the electronic
(and, therefore, the donor) characteristics of these substituents
by changing an encapsulated metal ion electronic configu-
ration via redox transitions.12 Varying the ribbed substituents
at a clathrochelate framework has been recognized as a
unique opportunity to stabilize unusual oxidation states of
an encapsulated metal ion. In particular, a new approach to
the synthesis of air-stable cobalt(I) complexes used a
macrobicyclic hexachloride ligand with six strongly electron-
withdrawing substituents in chelate π-conjugated R-dioxi-
mate fragments.13 Di- and triribbed-functionalized macro-
bicyclic iron and ruthenium(II) mono-, di-, tri-, tetra-, and
hexa-substituted tris-dioximates have previously been ob-
tained starting from their reactive tri- and hexachloride
clathrochelate precursors.12,14–20 Monoribbed-functionalized
(i.e., containing one or two functionalizing substituents in
one of the three dioximate fragments) iron(II) clathrochelates
have also been synthesized starting from the corresponding
mono- and dichloride precursors.18–23 The synthesis of
ribbed-functionalized clathrochelates with substituents, which
are able to coordinate a metal ion to produce polynuclear
complexes with interaction through the clathrochelate frame-
work metal centers, is of particular interest.12 We have
attempted to obtain a series of macrobicyclic monoribbed-
functionalized iron(II) tris-dioximates with a ribbed Vic-
dinitrile fragment, in particular, in the present study, to
synthesize complex 2, as a precursor of the monoribbed-
functionalized hybrid phthalocyaninoclathrochelates, under
different reaction conditions. Moreover, it was an unexpected
success that we isolated a chlathrochelate with an annulated
heterocyclic system of a new type when we changed the
reaction conditions. Such types of substituents are very
important for the design of DNA intercalators as well.
Experimental Procedures
General Procedures. The reagents used, FeCl2 ·4H2O, R-ben-
zyldioxime (H2Bd), BF3 ·O(C2H5)2, sorbents, and organic solvents,
were obtained commercially (Fluka). The dichloroglyoxime (de-
(18) Voloshin, Y. Z.; Zavodnik, V. E.; Varzatskii, O. A.; Belsky, V. K.;
Vorontsov, I. I.; Antipin, M. Y. Inorg. Chim. Acta 2001, 321, 116.
(19) Voloshin, Y. Z.; Varzatskii, O. A.; Palchik, A. V.; Vorontsov, I. I.;
Antipin, M. Y.; Lebed, E. G. Inorg. Chim. Acta 2005, 358, 131.
(20) Voloshin, Y. Z.; Varzatskii, O. A.; Palchik, A. V.; Starikova, Z. A.;
Antipin, M. Y.; Lebed, E. G.; Bubnov, Y. N. Inorg. Chim. Acta 2006,
359, 553.
(12) Voloshin, Y. Z.; Varzatskii, O. A.; Kron, T. E.; Belsky, V. K.;
Zavodnik, V. E.; Palchik, A. V. Inorg. Chem. 2000, 39, 1907.
(13) Voloshin, Y. Z.; Varzatskii, O. A.; Vorontsov, I. I.; Antipin, M. Y.
Angew. Chem., Int. Ed. 2005, 44, 3400.
(14) Voloshin, Y. Z.; Varzatskii, O. A.; Palchik, A. V.; Stash, A. I.; Belsky,
V. K. New J. Chem. 1999, 23, 355.
(15) Voloshin, Y. Z.; Varzatskii, O. A.; Kron, T. E.; Belsky, V. K.;
Zavodnik, V. E.; Strizhakova, N. G.; Nadtochenko, V. A.; Smirnov,
V. A. Dalton Trans. 2002, 1203.
(21) Voloshin, Y. Z.; Zavodnik, V. E.; Varzatskii, O. A.; Belsky, V. K.;
Palchik, A. V.; Strizhakova, N. G.; Vorontsov, I. I.; Antipin, M. Y.
Dalton Trans. 2002, 1193.
(16) Voloshin, Y. Z.; Varzatskii, O. A.; Palchik, A. V.; Strizhakova, N. G.;
Vorontsov, I. I.; Antipin, M. Y.; Kochubey, D. I.; Novgorodov, B. N.
New J. Chem. 2003, 27, 1148.
(22) Voloshin, Y. Z.; Belov, A. S.; Lebedev, A. Y.; Varzatskii, O. A.;
Antipin, M. Y.; Starikova, Z. A.; Kron, T. E. Russ. Chem. Bull. Int.
Ed. 2004, 53, 1171.
(17) Voloshin, Y. Z.; Varzatskii, O. A.; Vorontsov, I. I.; Antipin, M. Y.;
Lebedev, A. Y.; Belov, A. S.; Strizhakova, N. G. Russ. Chem. Bull.
Int. Ed. 2004, 53, 92.
(23) Voloshin, Y. Z.; Varzatskii, O. A.; Starikova, Z. A.; Antipin, M. Y.;
Lebedev, A. Y.; Belov, A. S. Russ. Chem. Bull. Int. Ed. 2004, 53,
1439.
2156 Inorganic Chemistry, Vol. 47, No. 6, 2008

Dichloride Fe(II) Clathrochelate with Dimercaptomaleodinitrile
Scheme 1
Scheme 2
obtained as described previously20 (see Supporting Informa-
tion).
Scheme 3
Syntheses. FeBd2(S2C2(CN)2Gm)(BF)2 (2). The complex
FeBd2(Cl2Gm)(BF)2 (1) (0.75 g, 1 mmol) was dissolved/suspended
in acetonitrile (25 mL), and then the solution of potassium salt of
mercaptomaleodinitrile (0.26 g, 1.2 mmol) in dry DMF (10 mL)
was added under argon. The reaction mixture was stirred for 40
min and then precipitated with water (50 mL). The precipitate was
filtered, dried in air, and extracted with methylene dichloride (40
mL, in two portions). The extract was dried with Na2SO4 and rotary
evaporated to dryness. The solid residue was dissolved in methylene
dichloride, and the solution was filtered through Silasorb SPH-300
(eluent: methylene dichloride-hexane 7:3 mixture). The head dark-
orange elute was rotary evaporated to dryness, and the solid residue
was reprecipitated from methylene dichloride with hexane. The
precipitate was washed with hexane and dried in vacuo. Yield:
noted as H2Cl2Gm) was obtained by chlorination of glyoxime
(H2Gm) as described in ref 24. The complex FeBd2(Cl2Gm)(BF)2
(1) was prepared as described in ref 21. Potassium salt of
dimercaptomaleodinitrile was synthesized as described in ref 25.
Analytical data (C, H, and N contents) were obtained with a
Carlo Erba model 1106 microanalyzer. The iron content was
determined spectrophotometrically with 5-sulfosalicylic acid.26,27
The MALDI-TOF, IR, UV–vis, NMR, and Mössbauer data were
(24) Ponzio, G.; Baldrocco, F. Gazz. Chim. Ital. 1930, 60, 415.
(25) Engler, E. M.; Patel, V. V. Chem. Commun. 1975, 387.
(26) Rodionova, T. V.; Beklemishev, M. K.; Dracheva, L. V.; Zolotov,
Y. A. Zh. Anal. Khim. 1992, 47, 1211.
(27) Stryjewska, E.; Krasnodebska, B.; Biala, H.; Teperek, J.; Rubel, S.
Chem. Anal. 1994, 39, 483.
Inorganic Chemistry, Vol. 47, No. 6, 2008 2157

Voloshin et al.
Figure 1. ORTEP view (50% probability of thermal ellipsoids) of clathrochelate molecule 2 (type A).
Figure 2. ORTEP view (50% probability of thermal ellipsoids) of clathrochelate molecule 3.
0.12 g (15%). Found: C, 50.11; H, 2.48; N, 13.53; Fe, 6.80. Calcd
for C34H20N8O6S2B2F2Fe: C, 50.03; H, 2.47; N, 13.73; Fe, 6.84%.
MS (MALDI-TOF): m/z (I, %): (positive range): 816(100) [M]+•;
790(30) [M - CN]+•; and 778(90) [M - CCN]+• and (negative
aqueous solution of tetra-n-butylammonium sulfate (0.6 mL, 0.4
mmol) were added to the reaction mixture under stirring. The
reaction mixture was left for 40 h at room temperature, and the
aqueous and organic phases were separated. The additional portion
of the clathrochelate products was extracted with benzene (20 mL).
The combined benzene extract was dried with Na2SO4 and rotary
evaporated to dryness. The solid residue was dissolved in methylene
dichloride and filtered through the Silasorb SPH-300 (eluent:
methylene dichloride). The head orange-red elute was evaporated
to dryness and reprecipitated from methylene dichloride with
hexane. The precipitate obtained was chromatographically separated
on Silasorb SPH-300 (eluent: methylene dichloride-hexane 2:1
mixture). The head dark-orange elute, containing mainly the
dichloride precursor, was thrown out, and the second red-violet elute
was collected. This elute was evaporated to dryness, and the solid
residue was washed with a small amount of methanol and hexane
and dried in vacuo. Yield: 0.20 g (23%). Found: C, 48.11; H, 2.63;
N, 14.32; S, 7.26; Fe, 6.26. Calcd for C36H23N9O7S2B2F2Fe: C,
1
range): –816 [M]-•. H NMR (CD2Cl2): δ (ppm) 7.25 (m, 20H,
Ph). 13C{1H} NMR (CD2Cl2): δ (ppm) 111.4 (s, CtN), 114.2 (s,
CdC), 128.4 (s, Ph), 128.9, 130.4, 130.8 (three s, Ph), 132.3 (s,
SCdN), 158.3 (s, PhCdN). IR (KBr): 1549 ν(SCdN), 1581
ν(PhCdN), 906, 937, 1064, 1107 ν(N-O), 1219 m ν(B-O) +
ν(B-F), 2229 ν(CtN). UV–vis (methylene dichloride): λmax (10-3
ꢀ, mol-1 L cm-1) 234(29), 262(11), 282(15), 309(11), 402(5.1),
468(22), 513(12) nm. Mössbauer 57Fe (mm s-1): IS ) 0.33, QS )
0.51.
FeBd2(TPHGm)(BF)2 (3). The complex FeBd2(Cl2Gm)(BF)2 (1)
(0.75 g, 1 mmol) was dissolved/suspended in nitromethane (10 mL),
and then the potassium salt of dimercaptomaleodinitrile (0.44 g, 2
mmol) was added under argon. The reaction mixture was stirred
for 2 h, and then benzene (50 mL), water (20 mL), and a 40%
2158 Inorganic Chemistry, Vol. 47, No. 6, 2008

Dichloride Fe(II) Clathrochelate with Dimercaptomaleodinitrile
Scheme 4
are caused by nucleophilic substitutions with the trans-form
of dimercaptomaleodinitrile: this results in the formation of
polymeric products. Low yield was also caused by both the
high reactivity and the thiophilicity of 2; similar behavior is
observed for the dichloride clathrochelate precursor 1.
Attempts to optimize the reaction conditions by the choice
of a solvent and to obtain 2 in higher yield failed. An
unexpected result was obtained when nitromethane was used
as a solvent: its reaction with the potassium salt of dimer-
captomaleodinitrile followed by the condensation of the
reaction products, which probably contain nitrothiophene 4,
with precursor 1 led to clathrochelate complex 3 with an
annulated thiazinothiophene heterocycle in the ribbed frag-
ment (Scheme 2).
The formation of clathrochelate 3 under the conditions of
interphase catalysis can be explained by hindering of the
dimercaptomaleodinitrile dianion-tetra-n-butylammonium
cation ionic pair phase transfer. At the same time, the
monocharged and lipophilic 2-cyano-3-mercapto-4-amino-
5-nitrothiophene anion, formed by the condensation of
dimercaptomaleodinitrile with nitromethane, can be ef-
ficiently transferred to the organic phase in the form of an
ionic pair with the Bu4N+ cation followed by nucleophilic
substitution with Vic-dihalogenide clathrochelate 1 (Scheme
2).
The feasible route for the formation of the substituted
nitrothiophene 4 is shown in Scheme 2. Attempts to isolate
pure heterocycle 4 failed because of the low stability of this
product and the presence of almost inseparable impurities.
Nevertheless, in situ condensation with reactive dichloride
precursor 1 gave the clathrochelate derivative 3 of this
heterocycle, and this complex proved to be sufficiently stable
to be isolated chromatographically. The second possible
pathway to this complex (nucleophilic substitution with one
of the two thiolate groups of mercaptomaleodinitrile at the
first step) is also shown in Scheme 2.
A literature search for structural fragment 5 (Scheme 3)
has revealed only two articles,31,32 and they describe the
different systems. This allows one to conclude that a
previously unknown heterocyclic system has been obtained.
The synthesized complexes 2 and 3 were characterized
by spectroscopic methods and X-ray crystallography. The
asymmetric unit cell of crystal 2 contains two crystallo-
graphically independent clathrochelate molecules A and B
with similar molecular structures (Figure 1) as well as the
benzene solvate molecules. The coordination polyhedron of
the encapsulated iron(II) ion possesses a distorted trigonal-
prismatic (TP) geometry. The almost parallel triangular bases
of the TP coordination polyhedron are formed by N1 ·N3 ·N5
and N2 ·N4 ·N6 nitrogen atoms, whereas its ribbed fragments
are formed by N1· · · N2, N3· · · N4, and N5· · ·N6
chelate cycles. The average distortion angle in passing
from a TP ( ) 0°) to a trigonal antiprism (TAP, ) 60°)
and the height h of the coordination polyhedron (the distance
between the centers of the TP triangular bases) are equal to
48.03; H, 2.42; N, 14.4; S, 7.33; Fe, 6.38%. MS (MALDI-TOF):
m/z: (positive range) 875 [M]+•; (negative range) –874 [M - H+]-.
1H NMR (CD2Cl2): δ (ppm) 10.08 (br s, 1H, NH), 7.26 (m, 20H,
Ph). 13C{1H} NMR (CD2Cl2): δ (ppm) 106.0 (s, CtN), 110.0 (s,
CCN), 126.3 (s, CNO2), 128.40, 128.41 (both s, Ph), 129.31 (s,
Ph), 129.33 (s, NCCS), 130.0 (s, NCCS), 130.7 (s, Ph), 130.83,
130.86 (both s, Ph), 132.3 (s, SCdN), 135.9 (s, NCdN), 157.5 (s,
PhCdN), 157.8 (s, PhCdN). IR (KBr): 1547 ν(SCdN + NCdN),
1576 ν(PhCdN), 899, 933, 1061, 1109 ν(N-O), 1221 m ν(B-O)
+ ν(B-F), 1620 δ(N-H), 2216 ν(CtN). UV–vis (methylene
dichloride): λmax (10-3 ꢀ, mol-1 L cm-1) 254 (30), 283 (18), 305
(14), 335 (5.6), 365 (5.5), 392 (4.8), 440 (8.7), 479 (19), 512 (6.0),
538 (10), 571 (6.8) 601 (4.2) nm. Mössbauer 57Fe (mm s-1): IS )
0.36, QS ) 0.63.
X-ray Crystallography. Details of the crystal data collection
and refinement parameters for 2 and 3 are listed in Table 1. Single
crystals of these complexes were grown from isooctane-benzene
and acetone-heptane mixtures at room temperature.
The single-crystal X-ray diffraction experiments for complexes
2 and 3 were carried out with Bruker SMART 1K and SMART
APEX II CCD diffractometers, using graphite monochromated Mo
KR radiation (λ ) 0.710 73 Å). Reflection intensities were
integrated using SAINT software28 and corrected for absorption
by semiempirical methods (SADABS program29).
The structures were solved by the direct method and refined by
a full-matrix least-squares method against F2 of all data, using the
SHELXTL software.30 Non-hydrogen atoms were refined with
anisotropic displacement parameters. The positions of hydrogen
atoms were calculated and included in refinement in isotropic
approximation by the riding model with Uiso(H) ) nUeq(C), where
n ) 1.5 for methyl groups and 1.2 for the other groups.
Results and Discussion
The easiest pathway to the precursor of the ribbed-
functionalized phthalocyaninoclathrochelates is based on the
condensation of reactive Vic-clathrochelate 1 with a salt of
dimercaptomaleodinitrile dianion (Scheme 1).
Despite the fact that the Vic-dichloride iron(II) clathro-
chelate easily reacts with thiolate anions,12,14–17,19–23 in
CH3CN/DMF, its nucleophilic substitution with the potas-
sium salt of dimercaptomaleodinitrile under different condi-
tions led to the target complex 2 only in low yield (∼15%).
The formation of a mixture of byproducts with low chro-
matographic mobility was also observed. These side reactions
(28) SMART and SAINT, Release 5.0, Area Detector Control and Integra-
tion Software; Bruker AXS: Madison, WI, 1998.
(29) Sheldrick, G. M. SADABS: A Program for Exploiting the Redundancy
of Area Detector X-Ray Data; University of Göttingen: Göttingen,
Germany, 1999.
(30) Sheldrick, G. M. SHELXTL, version 5.1; Bruker AXS: Madison, WI,
1997.
(31) Grol, C. J.; Rollema, H.; Dijkstra, D.; Westerink, B. H. C. J. Med.
Chem. 1980, 23, 322.
(32) Grol, C. J.; Rollema, H. J. Med. Chem. 1975, 18, 857.
Inorganic Chemistry, Vol. 47, No. 6, 2008 2159

Voloshin et al.
Table 2. Main Geometrical Parameters of Clathrochelate Molecules 2, 3, and 6
2
param
Fe-N (Å)
type A
type B
3
622
1.890(5)-1.920(5)
av 1.901(6)
1.299(7)-1.330(7)
av 1.312(7)
1.356(6)-1.377(6)
av 1.365(3)
1.498(8)
1.486(8)
1.471(8)
1.512(8)
1.450(8)
1.484(8)
1.418(8)
1.448(7)
1.469(7)
1.741(6)
1.752(6)
1.720(8)
1.727(8)
1.367(9)
110.6(5)
110.8(5)
110.9(5)
112.6(5)
114.1(4)
111.8(5)
119.1(4)
117.3(4)
118.3(4)
119.5(4)
118.9(4)
119.7(4)
29.7
1.884(5)-1.904(5)
av 1.897(5)
1.286(7)-1.331(7)
av 1.307(6)
1.358(6)-1.381(6)
av 1.368(6)
1.496(7)
1.489(7)
1.454(7)
1.509(7)
1.447(7)
1.487(7)
1.436(7)
1.457(7)
1.493(7)
1.760(7)
1.748(6)
1.723(7)
1.736(7)
1.365(9)
109.3(4)
110.4(5)
109.8(5)
112.1(5)
112.0(5)
111.0(5)
117.8(4)
117.4(4)
119.3(4)
119.7(4)
120.6(4)
120.0(4)
30.0
1.898(3)-1.916(3)
av 1.905(3)
1.299(5)-1.314(5)
av 1.307(5)
1.376(4)–1.387(4)
av 1.381(6)
1.494(6)
1.907(2)-1.919(2)
av 1.912
N-C (Å)
N-O (Å)
1.295(3)-1.310(4)
av 1.305(4)
1.362(3)-1.374(3)
av 1.369(3)
1.498(4)
1.481(4)
1.486(4)
1.501(4)
1.489(4)
B1-O1 (Å)
B1-O3 (Å)
1.486(5)
1.487(5)
1.505(5)
1.470(5)
1.484(5)
1.454(5)
1.464(5)
1.462(5)
B1-O5 (Å)
B2-O2 (Å)
B2-O4 (Å)
B2-O6 (Å)
1.483(4)
1.434(4)
C1-C2 (Å)
C3-C4 (Å)
C5-C6 (Å)
C1-S1 (Å)
1.740(5)
1.738(5)
1.724(3)
1.726(3)
1.429(6)
111.4(2)
111.1(2)
112.7(2)
112.6(2)
112.7(2)
113.3(2)
117.7(2)
118.2(2)
119.3(2)
119.8(2)
119.5(2)
119.6(2)
15.6
C2-S2 (Å)
S1-C9 (Å)
S2-C7 (Å)
C7-C9 (Å)
N1-O1-B1 (deg)
N2-O2-B2 (deg)
N3-O3-B1 (deg)
N4-O4-B2 (deg)
N5-O5-B1 (deg)
N6-O6-B2 (deg)
Fe-N1-C1 (deg)
Fe-N2-C2 (deg)
Fe-N3-C3 (deg)
Fe-N4-C4 (deg)
Fe-N5-C5 (deg)
109.4(3)
108.7(3)
112.5(3)
112.6(3)
112.5(3)
111.1(3)
118.3(3)
118.7(3)
119.3(3)
119.8(3)
119.9(3)
119.5(3)
2.4
Fe-N6-C6 (deg)
a
∆
(deg)
(deg)
b
24.4
39.3
2.324
24.6
39.4
2.318
25.8
39.2
2.314
23.5
39.1
2.333
Rc (deg)
hd (Å)
a Bend S · · ·S (S· · ·N) angle. b Distortion angle. c Bite angle (half the chelate angle). d Distance between the coordination polyhedron bases (the height
of the distorted TP).
24.4° and 2.325 Å, respectively. The encapsulated iron(II)
ion lies almost on the line that connects these centers (the
corresponding angle is equal to 177.9°).
The dithiacyclohexane ribbed fragment of molecule 2 is
nonplanar: the 1,4-dithiino-2,3-dicarbonitrile substituent has
a boat conformation, and the dihedral angle ∆ between its
planar fragments with a bend along the S1 · · · S2 line is
approximately 30°.
chelate framework than the corresponding values for two
diphenyl-substituted chelate cycles because of the effect of
the high conjugation of the 1,4-dithiine moiety on the
geometry of the functionalized dioximate ring.
Both crystals 2 and 6 contain benzene solvate molecules
(2·2.5C6H6 and 6·1.5C6H6). However, their crystal packings
are different: in 6·1.5C6H6, the crystal packing is determined
by weak S2 · · ·F interactions, as well as by the diazine cycle
of the quinoxaline system · · · solvate benzene molecule
attractive interactions, whereas in 2 · 2.5C6H6, the crystal
packing is dictated by van der Waals interactions.
The asymmetric unit cell of crystal 3 contains one
clathrochelate molecule, 2.5 solvate acetone molecules, and
half a disordered solvate heptane molecule. The crystal
packing of 3 is determined by van der Waals interactions.
The molecular structure of clathrochelate 3 (Figure 2)
closely resembles that of complex 2. The coordination
polyhedron of the encapsulated iron(II) ion adopts a distorted
TP geometry. TP triangular bases are formed by the
N1· N3· N5 and N2 · N4· N6 nitrogen atoms. The average
distortion angle , bite angle R, and height h values are listed
in Table 2.
The clathrochelate framework of the previously described22
dithiine-containing clathrochelate 6 (Scheme 4) is identical
to that of clathrochelate molecule 2, but their functionalized
ribbed fragments are different (the tricyclic 1,4-dithiino-2,3-
quinoxaline fragment in the case of complex 6 instead of
the monocyclic 1,4-dithiino-2,3-dicarbonitrile one in 2). The
TP iron(II) coordination polyhedron in molecule 6 is slightly
less distorted than that in clathrochelate 2. This might be
accounted for by the influence of a bulkier tricyclic system
that reduces the lability of the clathrochelate framework of
6: the dithiine fragment in this molecule is drastically
flattened (the bend along the S1 · · · S2 line is half that in
molecule 2).
The B-O (B1-O1 and B2-O2) distances are higher and
the N-O-B (N1-O1-B1 and N2-O2-B2) and Fe-N-C
(Fe-N1-C1 and Fe-N2-C2) bond angles are smaller in
the 1,4-dithiine-containing chelate fragment of the clathro-
As in the case of clathrochelate 2, in molecule 3, the B-O
bond lengths are slightly longer, and the N-O-B and
2160 Inorganic Chemistry, Vol. 47, No. 6, 2008

Dichloride Fe(II) Clathrochelate with Dimercaptomaleodinitrile
Fe-N-C bond angles are slightly smaller in the NS-
containing chelate fragment than those in phenyl-substituted
fragments (Table 2). The NS-containing six-membered cycle
is nearly planar (mean deviation is equal to 0.028 Å), and
the C1-C2 bond is slightly shorter than the C3-C4 and
C5-C6 bonds. An intramolecular weak hydrogen bond is
formed by the NH group and the O8 atom of the adjacent
nitro substituent.
annulated heterocyclic fragment. In the case of complex 2,
the number of bands that were assigned to the π-π*
transitions in both the clathrochelate framework and the
ribbed dithiadinitrile fragment is significantly less.
57Fe Mössbauer parameters (isomeric shift [IS] and quad-
rupole splitting [QS]) of the clathrochelates 2 and 3
characterize them as low-spin iron(II) N6 complexes with a
TP-TAP geometry. QS values allow one to deduce the
distortion angle values for these complexes with the use
of a modern partial QS concept.33 The distortion angle
values for complexes 2 and 3 were calculated using a simple
model:33 QS ) PQS(12 - 18 cos2 R/cos2( /2)), where PQS
is the partial quadrupole splitting with an approximate value
of +0.5 mm s-1 for macrobicyclic tris-diiminates. The
slightly increased QS values obtained for the synthesized
compounds (see Experimental Procedures) as compared to
those calculated from this equation (0.50 mm s-1 for 2 and
0.46 mm s-1 for 3) can be accounted for by the fact that the
molecules have no C3 symmetry axis passing through the
apical boron atoms and the central iron ion, and this induces
an additional increase in the electric field gradient.
The solution 1H and 13C{1H} NMR spectra of complexes
2 and 3 confirmed the composition and symmetry of their
molecules. The 1H NMR spectrum of clathrochelate 2
contains only the broadened signal of the phenyl substituent
1
protons at ∼7.3 ppm, whereas in the H NMR spectrum of
complex 3, besides the line of this type, a new signal appears
as the singlet line that is characteristic of the NH- proton
in the expected ratio of line integral intensities (20:1). The
13C NMR spectra of the clathrochelates obtained proved to
be much more informative. The 13C NMR spectrum of
complex 2 confirmed both the composition and the presence
of a symmetry plane passing through the middle of the
chelate C-C bonds, the encapsulated iron(II) ion, and the
middle of the CdC bond in the ribbed functionalized
fragment. In particular, the singlet signal, assigned to
azomethine carbon atoms in the PhCdN groups, was
observed at ∼156 ppm. Such symmetry was not observed
for molecule 3, and its 13C NMR spectrum contains two
signals that were assigned to the azomethine carbon atoms
of the nonequivalent PhCdN groups. This spectrum also
contains the signals of the heterocyclic fragment carbon
atoms.
We plan to carry out the tetramerization of the dinitrile
chlathrochelate 2 as well as the reaction of macrocyclization
with phthalodinitrile, which leads to the formation of
functionalized hybrid phthalocyanino-mono-, -di-, -tri-, and
-tetra-clathrochelates. The intercalation into the DNA struc-
ture of intensive colored chlathrochelate 3 with an annulated
highly conjugated π-system as a potential molecular probe
will also be studied.
Acknowledgment. The authors gratefully acknowledge the
support of the RFBR (Grants 05-03-33184, 06-03-32626, 06-
03-90903, and 07-03-12183) and RAS (Program 7).
The solution UV–vis spectrum of clathrochelate complex
3 also confirmed the absence of symmetry elements in this
molecule. Six bands of high intensity (ꢀ ) ∼4 to 20 × 103
mol-1 L cm-1) in the visible region were observed: they can
be assigned to the Fed f Lπ* charge transfer bands (CTBs).
In contrast, in the UV–vis spectrum of complex 2 (the
molecule of which has a symmetry plane), only two CTBs
were observed in this region. The spectrum of clathrochelate
complex 3 in the UV region contains the highly intensive
bands that were assigned to the π-π* transitions in the
conjugated R-dioximate fragments and some bands of close
intensity assigned to the π-π* transitions in the ribbed
Supporting Information Available: Details of MALDI-TOF,
IR, UV–vis, NMR, and Mössbauer data collections and listings of
crystal and refinement data, bond distances, angles, and thermal
parameters for 2 and 3. This material is available free of charge
via the Internet at http://pubs.acs.org.
IC701452G
(33) Voloshin, Y. Z.; Polshin, E. V.; Nazarenko, A. Y. Hyperfine Interact.
2002, 141–142, 309.
Inorganic Chemistry, Vol. 47, No. 6, 2008 2161