Synthesis and complexation studies of 16-membered [1+1] selenaaza- and some related macrocycles

Article abstract of DOI:10.1016/j.ica.2010.03.020

A novel 16-membered [1+1] unsymmetrical selenaaza Schiff base macrocycle, 8,9,10,11-tetrahydo-7H-dibenzo-[d,o][1,3,7,10,13]diselenatriazacyclohexadecine (5) with N₃Se₂ donor set, has been synthesized by cyclocondensation of di(o-form

Full text of DOI:10.1016/j.ica.2010.03.020

Inorganica Chimica Acta 363 (2010) 2905–2911
Contents lists available at ScienceDirect
Inorganica Chimica Acta
journal homepage: www.elsevier.com/locate/ica
Synthesis and complexation studies of 16-membered [1+1] selenaaza- and
some related macrocycles
b
Tapash Chakraborty a, Kriti Srivastava a, Snigdha Panda a, Harkesh B. Singh a, , Ray J. Butcher
*
a Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400 076, India
b Department of Chemistry, Howard University, Washington, DC 20059, USA
a r t i c l e i n f o
a b s t r a c t
Article history:
A novel 16-membered [1+1] unsymmetrical selenaaza Schiff base macrocycle, 8,9,10,11-tetrahydo-7H-
dibenzo-[d,o][1,3,7,10,13]diselenatriazacyclohexadecine (5) with N3Se2 donor set, has been synthesized
by cyclocondensation of di(o-formylphenylseleno)methane and diethylenetriamine. Reduction of 5 with
NaBH4 afforded 6,7,8,9,10,11,12,13-octahydro-5H-dibenzo-[d,o][1,3,7,10,13]diselenatriazacyclohexade-
cine (6). Macrocycle, 10,11,12,13,14,15,16,26,27,28,29,30,31,32-tetradecahydrotetrabenzo[b,k,n,w][1,13,
5,9,17,21]diselenatetraazacyclotetracosine (2b) was synthesized similarly from di(o-formylphenyl)sele-
nide and 1,3-diaminopropane followed by reduction with NaBH4. Single crystal X-ray structures of 5
and 2b have been determined. Attempted complexation reactions of 5 with Zn(II), Cd(II), Hg(II), Pd(II)
and Cu(II) ions and those of 6 with Ag(I), Hg(II) and Pd(II) ions are reported. 28-Membered selenaaza
macrocycle 2c on reaction with HgCl2 and NH4PF6, provided a dinuclear Hg(II) complex 9. Complex 9
has been characterized by single crystal X-ray structure.
Received 1 February 2010
Received in revised form 8 March 2010
Accepted 10 March 2010
Available online 17 March 2010
Dedicated to Animesh Chakravorty
Keywords:
Schiff base macrocycle
Selenium
Mercury
[1+1] Cyclocondensation
Mercurous ion
Ó 2010 Elsevier B.V. All rights reserved.
1. Introduction
with the homo donor selenium coronands as well as with mixed
chalcogenacrowns.
A selenapyridinophane and its Ni(II) and
The design and synthesis of new macrocyclic ligands and the
study of their complexation properties has been an active area of
research because of their existing and potential applications in
many aspects of chemistry, medicine, and chemical industry
[1]. In this context, mixed donor chalcogen macrocycles have at-
tracted a great deal of interest [2]. Pinto and co-workers pio-
neered the chemistry of selenium coronands [3]. They
Cu(II) complexes have been described by Muralidharan et al.
[5]. A macrobicyclic cage incorporating N3Se3 donor set and its
Co(III) complex has been reported by Jackson and co-workers
[6]. There are a few reports on the synthesis of selenaaza crown
ethers [7].
Se Se
Se Se
Se
Se
Se
synthesized
a series of homo donor selenacrowns including
O
O
O
12-, 14-, 18- and 24-membered rings and studied their complex-
ation properties [3a–c]. Reid and co-workers [2a,4] have also
made a significant contribution in this area. They have reported
a series of complexes of transition metals and p-block elements
Se
Se
[9]aneO2Se
[8]aneSe2
[10]OSe2
[16]aneSe4
Our group has been involved in the synthesis and complexa-
tion studies of Schiff base selenaaza macrocycles and their re-
duced derivatives. Synthesis and complexation properties of
22-, 24-, and 28-membered selenaaza macrocycles 1a–d, have
been reported [8]. Recently, the complexation studies of mac-
rocycle 2a with various transition metal ions were reported
[8e].
* Corresponding author.
E-mail address: chhbsia@chem.iitb.ac.in (H.B. Singh).
0020-1693/$ - see front matter Ó 2010 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2010.03.020

2906
T. Chakraborty et al. / Inorganica Chimica Acta 363 (2010) 2905–2911
Interestingly the reaction of 2c [8a] with Hg(OAc)2/NH4PF6 provided
a dinuclear complex 2d, where a mercurous ion, Hg22þ was trapped
in the macrocyclic cavity [8c]. In continuation of our studies on
Schiff base selenaaza macrocycles, we report here the synthesis of
a novel [1+1] cyclocondensed 16-membered selenaaza Schiff base
macrocycle and its reduced derivative. Attempted complexation of
the 16-membered macrocycles with several metal ions is described.
In view of the interesting complexation behavior of 2c with
Hg(OAc)2, reactions of 2b and 2c with mercuric salts have also been
investigated.
reduced macrocycle 6 (Scheme 2). The 24-membered macrocycle
2b was similarly prepared by reduction of the corresponding Schiff
base macrocycle 1c [8d] with NaBH4. The 28-membered macrocy-
cle 2c was prepared by following the reported procedure [8a].
The precursors and the macrocycles were characterized by ele-
mental analysis, NMR (1H, 13C and 77Se), IR and mass spectrometry.
The 77Se NMR chemical shift of di(o-formylphenylseleno)methane,
4 (348 ppm) shows an upfield shift of 120 ppm with respect to 3
(468 ppm) indicating weaker intramolecular Seꢀ ꢀ ꢀO interaction
[9a]. The 77Se NMR chemical shift of the macrocycle 5 (286 ppm)
showed an upfield shift of ca. 60 ppm with respect to the bis-alde-
hyde 4. Interestingly, the 77Se NMR spectrum of 6 (303 ppm)
showed a small downfield shift of ca. 17 ppm with respect to the
Schiff base macrocycle 5. Macrocycle 2b showed the 77Se NMR sig-
nal at 326 ppm.
2. Result and discussion
2.1. Ligand syntheses
Bis(o-formylphenylseleno)methane, (4) was synthesized from
the reaction of in situ generated sodium selenolate with dibromo-
methane (Scheme 1). The precursor di(o-formylphenyl) diselenide
(3) was prepared from o-chlorobenzaldehyde and sodium disele-
nide [9] and crystallized from a chloroform/hexane solution.
The Schiff base selenaaza macrocycle 5 was obtained by cyclo-
condensation of 4 with diethylenetriamine without recourse to a
metal ion template as the major product. The MALDI-TOF analysis
of the crude precipitate obtained in the synthesis of 5 also showed
presence of the [2+2] cyclocondensed product along with the
molecular ion peak for the [1+1] cyclocondensed product. Macro-
cycle 5 was purified by crystallization from acetonitrile and its
structure was confirmed by the X-ray structure determination
(vide infra). Reduction of 5 with NaBH4 in ethanol provided the
2.2. Complexation studies
Reaction with AgClO4ꢀxH2O gave a pinkish white precipitate
whose elemental analysis indicated formation of a complex 7 with
1:1 composition (Scheme 3).
The 77Se NMR chemical shift of complex 7 (424 ppm) showed a
downfield shift of about 120 ppm compared to free ligand 6
(303 ppm) indicating coordination through both the selenium
atoms. However, the 1H NMR spectrum in DMSO-d6 was too
complex to interpret. Attempts to grow single crystals of 7 were
O
O
O
O
(i)
Se
Se
Se
Se
(ii)
4
3
Scheme 2. (i) H2NCH2CH2NHCH2CH2NH2, CH3CN, reflux, 24 h. (ii) NaBH4, EtOH,
Scheme 1. (i) Na, THF, naphthalene, (ii) CH2Br2.
reflux, 3 h.

T. Chakraborty et al. / Inorganica Chimica Acta 363 (2010) 2905–2911
2907
Table 1
Significant bond lengths (Å) and torsion angles (°) for 3.
Se1a–C1a
Se1a–Se2a
Se2a–C8a
C1a–Se1a–Se2a–C8a
C1b–Se1b–Se2b–C8b
1.925(3)
2.3347(5)
1.942(4)
Se1b–C1b
Se1b–Se2b
Se2b–C8b
ꢁ87.80(15)
90.53(14)
1.928(3)
2.3354(6)
1.932(4)
Scheme 3. Complexation of 6 with Ag(I): (i) AgClO4ꢀxH2O, MeOH, RT, 30 min.
unsuccessful. Based on elemental analysis and 77Se NMR data, a
definitive structure for 7 could not be assigned. Attempted com-
plexation reactions of 5 with HgCl2, Cu(OAc)2ꢀH2O, Zn(ClO4)2ꢀ6H2O
and Cd(ClO4)2ꢀH2O led to hydrolysis of the macrocycle. Reaction of
5 with Pd(COD)Cl2, followed by addition of NH4PF6 afforded a red-
dish orange precipitate of indefinite composition. Reactions of 6
with HgCl2/NH4PF6 and Pd(COD)Cl2 also afforded products of
indefinite composition. Similarly, the reaction of 2b with
Hg(OAc)2/NH4PF6 afforded a white precipitate. It was found to be
insoluble in common organic solvents and was sparingly soluble
in DMSO, CH3CN and CH3OH. The 77Se NMR was recorded in CD3CN
(313 ppm). It shows an upfield shift of 13 ppm with respect to the
free ligand (326 ppm). Though the elemental analysis data indi-
cated formation of a complex of stoichiometry [2bꢀHg2](PF6)2 (8),
the small 77Se NMR chemical shift and absence of 1J(199Hg–77Se)
coupling are not supportive of any coordination through selenium.
Fig. 1. ORTEP diagram of ligand 3. Thermal ellipsoids are drawn at the 50%
probability level.
2.2.1. Reaction of 2c with HgCl2
On addition of an equimolar mixture of HgCl2 and NH4PF6 to a
refluxing solution of macrocycle 2c in methanol, a white precipi-
tate of 9 was obtained (Scheme 4). The filtrate on standing for long
afforded a small amount of crystalline solid suitable for X-ray anal-
ysis. It was found to be insoluble in all common organic solvents
and only sparingly soluble in DMSO, CH3CN and CH3OH. The 1H
and 13C NMR spectra were too complex and no satisfactory infor-
mation could be obtained.
T-shaped. The difference between the torsion angles C1a–Se1a–
Se2a–C8a [ꢁ87.80(15)°], C1b–Se1b–Se2b–C8b [90.53(14)°] in the
two moieties of the asymmetric unit is significant compared to
the almost identical values of the corresponding torsion angles in
the reported polymorph (ꢁ86.28 and ꢁ86.32°) [10].
2.3.2. Crystal structure of 4
Attempts to record 77Se NMR spectrum in hot CD3OD showed
signals at 299 and 1180 ppm, indicating dissociation and decom-
position of the complex on heating. The 77Se NMR signal of the free
ligand in CDCl3 appeared at d 328 ppm [8a]. The elemental analysis
did not give satisfactory result. This may be due to improper com-
bustion of the heavy metal complex [8c]. The crystallographic data
(vide infra) showed the macrocycle to entrap two Hg(II) ions.
Compound 4 crystallized in the space group P21/n of the mono-
clinic system. The unit cell contains four discrete molecules. Se-
lected bond lengths and bond angles and torsion angles are
shown in Table 2 and the ORTEP diagram is shown in Fig. 2. Geom-
etry around both the selenium atoms is T-shaped.
The nonbonding intramolecular distances, Se1ꢀ ꢀ ꢀO1 (2.751 Å)
and Se2ꢀ ꢀ ꢀO2 (2.770 Å), are less than the sum of their van der
Waals radii (3.40 Å) [11] showing a significant nonbonded interac-
tion. These Seꢀ ꢀ ꢀO distances are smaller than the Seꢀ ꢀ ꢀO distance
(2.812 Å) observed in di(o-formylphenyl) selenide [8a], however,
these distances are greater than those observed in 3 (2.751 Å,
2.3. Crystal structures
2.3.1. Crystal structure of 3
The structure of diselenide 3 has been reported earlier [10]. It
was isolated as colorless plates from CHCl3/Et2O in chiral space
group Pca21 of the orthorhombic system. The crystallization of 3
from CHCl3/hexane afforded a new polymorph as colorless needles
in the space group P21/c of the monoclinic system. Selected bond
lengths and torsion angles are shown in Table 1 and the ORTEP dia-
gram is shown in Fig. 1. The structure is quite similar to the
reported structure. The geometry around each selenium atom is
Table 2
Significant bond lengths (Å), bond angles (°) and torsion angles (°) for 4.
Se1–C1A
1.909(5) C1A–Se1–
C
1.943(5) C1B–Se2–C 101.1(2) C1B–Se2–C–Se1
1.913(5) Se1–C–Se2 106.8(2) C1A–Se1–C–Se2
100.6(2) Se2–C
1.961(5)
Se1–C
Se2–C1B
179.0(2)
73.9(3)
Scheme 4. Complexation of 2c with HgCl2. (i) HgCl2 + NH4PF6 (1:1, 2 equiv).

2908
T. Chakraborty et al. / Inorganica Chimica Acta 363 (2010) 2905–2911
Selected bond lengths and bond angles are given in Table 3 and
the ORTEP diagram is shown in Fig. 3. The molecular structure of
5 in the solid state shows that the molecule is unsymmetrical
and puckered with only one Seꢀ ꢀ ꢀN intramolecular interaction be-
tween Se2 and N3 (2.744 Å); the sum of the van der Waals radii of
selenium and sp2 hybridized nitrogen being 3.4 Å [11]. This dis-
tance is shorter than the Seꢀ ꢀ ꢀN distances in 1d (2.814 Å) [8a]
and 1b (2.816 Å and 2.782 Å) [8f], however, longer than that in
1a (2.723 Å and 2.729 Å) [8d]. The angle C–Se2–N3 is almost linear
(173.90°). The other imine nitrogen atom N1 is turned away from
the nearest Se atom Se1. The geometry around Se2 is T-shaped
whereas the geometry around Se1 is V-shaped. The impact of intra-
molecular coordination is not evident from the trans-C(sp3)–Se
bond lengths: C–Se1 [1.961(2) Å] and C–Se2 [1.962(2) Å] being al-
most equal. The distance C18–Se2 [1.923(2) Å] is shorter than the
distance C1–Se1 [1.936(1) Å]. These bond lengths are comparable
to the corresponding lengths reported for the similar compounds
1a–d [8].
Fig. 2. ORTEP diagram of ligand 4. Thermal ellipsoids are drawn at the 50%
probability level.
2.3.4. Crystal structure of 2b
Macrocycle 2b crystallized in the P21/c space group of the
monoclinic system. The unit cell contains two discrete molecules.
Selected bond lengths and bond angles are given in Table 4 and OR-
TEP diagram is shown in Fig. 4.
Table 3
Significant bond lengths (Å) and bond angles (°) for 5.
C–Se1
C–Se2
C1–Se1
C18–Se2
C7–N1
N1–C8
1.961(2)
1.962(2)
1.936(2)
1.923(2)
1.257(3)
1.461(3)
C6–C7–N1
N1–C8–C9
C9–N2–C10
C1–Se1–C
C18–Se2–C
Se1–C–Se2
122.1(2)
110.32(19)
112.88(18)
96.17(9)
99.21(10)
108.57(11)
Unlike the case of Schiff base macrocycles 1a–d and 5, where
there is one short (much shorter than the sum of the van der Waals
radii) and one long (much longer than the sum of the van der
Waals radii) Seꢀ ꢀ ꢀN distance per Se atom, the intramolecular Seꢀ ꢀ ꢀN
distances: Seꢀ ꢀ ꢀN1a (3.284 Å) and Seꢀ ꢀ ꢀN1b (3.074 Å) in the re-
duced Schiff base macrocycle 2b are almost equal and only margin-
ally shorter than the sum of the van der Waals radii of Se and N
(3.45 Å) [11]. The transannular Seꢀ ꢀ ꢀSe distance (6.395 Å) is much
longer than the sum of the van der Waals radii (3.8 Å). The geom-
etry around the Se atom is V-shaped with the C1a–Se–C1b angle
being 96.27(7)°.
Table 4
Significant bond lengths (Å) and bond angles (°) for 2b.
Se–C1a
Se–C1b
C7a–N1a
N1a–C8a
1.9366(18)
1.9274(17)
1.460(3)
C1a–Se–C1a
C7a–N1a–C8a
C7b–N1b–C8b
Se–C1a–C2a
96.27(7)
113.27(16)
112.72(15)
120.68(13)
1.467(3)
Fig. 3. ORTEP diagram of 5. Thermal ellipsoids are drawn at the 50% probability
level.
2.720 Å, 2.729 Å, 2.725 Å) [10]. The O1–Se1–C and O2–Se2–C an-
gles are almost linear. The two fragments of the molecule on either
side of the central carbon atom are planar and inclined almost per-
pendicular to each other.
2.3.3. Crystal structure of 5
Macrocycle 5 crystallized in the space group P21/c of the mono-
clinic system. The unit cell contains four discrete molecules.
Fig. 4. ORTEP diagram of 2b. Thermal ellipsoids are drawn at the 50% probability
level; hydrogen atoms and solvent molecules are removed for clarity.

T. Chakraborty et al. / Inorganica Chimica Acta 363 (2010) 2905–2911
2909
Table 5
point apparatus in capillary tubes and were uncorrected. Nuclear
magnetic resonance spectra, 1H (400 MHz) and 13C (100.57 MHz)
were recorded on a Varian VXR 400S and 77Se (57.22) on a Varian
VXR 300S spectrometer. Chemical shifts are cited with respect to
Me4Si as internal standard (1H, 13C) and Me2Se as external standard
Significant bond lengths (Å) and bond angles (°) for 9.
Hg1–N1
Hg1–N2
Hg1–N3
Hg1–Cl1
Hg1–Cl1i
Hg1–F11
2.333(10)
2.301(11)
2.481(9)
2.412(3)
3.026(3)
2.747(7)
N1–Hg1–N3
N2–Hg1–Cl1
Cl1–Hg1–F11
N1–Hg1–N2
N1–Hg1–Cl1
Cl1–Hg1–N3
N2–Hg1–N3
143.8(3)
163.3(3)
166.5
77.5(4)
116.4(3)
96.0(2)
74.0(3)
(
77Se). Elemental analyses were performed on a Carlo Erba elemen-
tal analyser model 1106. The IR spectra were recorded as KBr pel-
lets on a Nicolet Impact 400 FTIR spectrometer. The ESI mass
spectra were recorded on
spectrometer.
a Q-Tof micro (YA-105) mass
4.1. Syntheses of ligands
4.1.1. Synthesis of di(o-formylphenylseleno)methane (4)
To a mixture of sodium (0.46 g, 20 mmol) and catalytic amount
of naphthalene (0.256 g, 2 mmol) in dry tetrahydrofuran (50 mL)
was added di(o-formylphenyl) diselenide (3.68 g, 10 mmol) and
the reaction mixture stirred overnight. To this, dibromomethane
was added in excess and the mixture stirred at room temperature
for 1 h. The reaction mixture was quenched with 20 mL of metha-
nol and 50 mL of water and extracted with dichloromethane
(3 ꢂ 50 mL). The solution was dried over anhydrous sodium sul-
fate, filtered and concentrated to give a yellow solid which was
recrystallized from chloroform. Yield: 1.2 g (32%); mp 150–
152 °C. Anal. Calc. for C15H12O2Se2: C, 47.14; H, 3.16. Found: C,
47.06; H, 2.61%. 1H NMR (CDCl3): d 4.16 (s, 2H, SeCH2Se), 7.38–
7.42 (m, 2H), 7.52–7.54 (m, 2H), 7.55–7.66 (m, 2H), 7.83–7.85
(2H), 10.13 (s, –CHO). 13C NMR (CDCl3): d 14.94 (SeCH2Se),
125.88, 129.01, 134.27, 134.64, 135.55, 138.29 (aromatic C),
192.68(–CHO). 77Se NMR (CDCl3): d 348. ESI-MS: m/e 383 (M+),
199 (C8H7OSe+). IR(cmꢁ1): 1694, 1661.
Fig. 5. ORTEP diagram of 9. Thermal ellipsoids are drawn at the 50% probability
level; hydrogen atoms and solvent molecules are removed for clarity.
2.3.5. Crystal structure of 9
ꢀ
The dinuclear mercury complex 9 crystallized in the P1 space
group of the triclinic system. The unit cell contains two discrete
molecules. Selected bond lengths and bond angles are given in Ta-
ble 5 and ORTEP diagram is shown in Fig. 5.
4.1.2. Synthesis of Schiff base macrocycle (5)
In a 250 mL three-neck round bottomed flask bis-aldehyde 4
(764 mg, 2 mmol) was suspended in 125 mL of acetonitrile. To this
diethylenetriamine (0.2 mL, 2 mmol) was added via a syringe and
the reaction mixture was refluxed for 24 h. It was then allowed
to cool when a white turbidity appeared. Upon further cooling a
white crystalline solid precipitated out. The precipitate was filtered
and air dried. Yield: 480 mg, 53%; mp 168–170 °C. Anal. Calc. for
Geometry around mercury centers is distorted tetrahedral
where each mercuric ion bonded to three nitrogen atoms and a
chloride ion. Another Clꢁ and a PFꢁ6 ions are within its van der
Waals radius. The molecule is centrosymmetric and one half of
the molecule represents the asymmetric unit. The Hg1–N [2.333
(10) Å], Hg1–N2 [2.301 (11) Å], Hg1–N3 [2.481 (9) Å] distances
are marginally greater than the sum of the covalent radii of Hg
(1.49 Å) and N (0.75 Å), however, smaller than the sum of their
van der Waals radii (3.1 Å) [11]. The transannular Seꢀ ꢀ ꢀSe distance
(10.354 Å) is smaller than that in Hg22þ trapped macrocycle
(11.1962 Å) [8c]. The Seꢀ ꢀ ꢀHg distances (5.309 and 5.692 Å) are
much greater than the sum of their van der Waals radii indicating
no Se–Hg interaction in the solid state.
C19H21N3Se2: C, 50.79; H, 4.71; N, 9.35. Found: C, 50.98; H, 4.28;
N, 9.57%. 1H NMR (CDCl3): d 1.71 (b, NH), 3.03–3.05 (m, 4H),
3.87–3.90 (m, 4H), 3.91(s, 2H), 7.25–7.28 (m, 4H), 7.52–7.54 (m,
2H), 7.70–7.72 (m, 2H), 8.79 (s, 2H). 13C NMR (CDCl3): d 23.19
(SeCH2Se), 49.97 (CH2NH), 61.20 (CH2N@C), 127.17, 130.33,
130.77, 133.05, 135.48, 136.74 (aromatic C), 162.86 (C @N). 77Se
NMR (CDCl3): d 286. IR(cmꢁ1): 1637.
3. Conclusion
4.1.3. Synthesis of reduced Schiff base macrocycle (6)
In conclusion, a 16-membered [1+1] selenaaza Schiff base mac-
rocycle and its reduced derivative and a 24-membered [2+2] re-
duced selenaaza Schiff base macrocycle have been synthesized.
Attempted complexation of the reduced 16-membered macrocycle
with Ag(I) indicated formation of a to 1:1 complex. The 28-mem-
bered reduced selenaaza macrocycle afforded a binuclear mercuric
ion (Hg2+) complex.
To a suspension of 5 (450 mg, 1 mmol) in 35 mL of ethanol was
added sodium borohydride in excess and the reaction mixture re-
fluxed for 3 h. The reaction mixture was cooled, quenched with
water (50 mL) and extracted with dichloromethane (50 mL ꢂ 2).
The organic phase was dried over anhydrous sodium sulfate, fil-
tered and concentrated to give a white solid. It was recrystallized
from dichloromethane/acetonitrile (1:2). Yield: 355 mg, 78%; mp
137–139 °C. Anal. Calc. for C19H25N3Se2: C, 50.34; H, 5.56; N,
9.27. Found: C, 50.16; H, 5.11; N, 9.95%. 1H NMR (CDCl3): d 1.73
(b, NH), 2.69–2.72 (m, 4H, CH2NH), 2.80–2.83 (m, 4H,
ArCH2NHCH2), 3.87 (s, 4H, ArCH2), 4.19 (s, 2H, SeCH2Se), 7.19–
7.27 (m, 6H), 7.54–7.56 (m, 2H). 13C NMR (CDCl3): d 21.50
(SeCH2Se), 48.82 (CH2NH), 49.30 (CH2NHCH2Ar), 54.91 (ArCH2NH),
127.40, 128.49, 130.28, 132.73, 133.34, 141.50 (aromatic C). 77Se
NMR (CDCl3): d 303. IR(cmꢁ1): 1651, 3455.
4. Experimental
All reactions were carried out under nitrogen or argon using
standard vacuum-line techniques. Solvents were purified and dried
by standard procedures and were distilled prior to use. Ligands 1d,
2c [8a], 1c [8d], and 3 [9] were prepared by the reported proce-
dures. Melting points were recorded on a Veego VMP-I melting

2910
T. Chakraborty et al. / Inorganica Chimica Acta 363 (2010) 2905–2911
Table 6
Crystal data and structure refinement for 3, 4, 5, 2b and 9.
3
4
5
2b
9
Formula
C
14H10O2Se2
C15H12O2Se2
382.17
monoclinic
P21/n
8.3118(2)
11.2184(4)
15.2597(5)
90
103.952
90
1380.92(7)
4
C19H21N3Se2
449.31
monoclinic
P21/c
17.8402(7)
5.43560(10)
20.6628(8)
90
114.833(5)
90
1818.45(11)
4
1.641
200(2)
4.76–32.62
4.072
C34H40N4Se2
666.62
monoclinic
P21/c
9.7112(6)
5.8603(3)
26.4561(15)
90
94.500(1)
90
1500.99(15)
2
1.466
223
2.1–28.3
2.494
0.0274
C36H46Cl2F12Hg2N6P2Se2
1482.73
Formula weight
Crystal system
Space group
a (Å)
b (Å)
c (Å)
368.14
monoclinic
P21/c
7.84939(15)
17.0080(3)
19.9127(4)
90
93.9223(18)
90
2652.17(9)
8
1.844
295(2)
4.45–77.42
6.899
triclinic
ꢀ
P1
7.8967(18)
12.006(3)
12.657(3)
102.947(4)
94.861(4)
107.253(4)
1102.1(4)
1
2.234
103(2)
1.84–28.30
8.890
0.0637
a
(°)
b (°)
c
(°)
V (Å3)
Z
Dcalc (Mg mꢁ3
T (K)
)
2.298
296(2)
4.54–32.57
6.686
0.0622
0.1030
4270/0/172
1.222
h (°)
Absorption coefficient (mmꢁ1
)
Final R(F) [I > 2
r
(I)]a
r
0.0399
0.0536
5542/0/325
1.040
0.0351
0.0562
5993/0/221
0.835
wR(F2) indices[I > 2
(I)]
0.0631
3646/0/208
1.042
0.1583
5125/30/318
1.057
Data/restraints/parameters
Goodness of fit (GOF) on F2
ꢄ
ꢂ
ꢃꢅ
1=2
ꢀ
ꢁ
h
ꢀ
ꢁi
2
ꢀ
ꢁ
2
P
P
P
P
Definitions: RðFoÞ ¼ kFoj ꢁ jFck= jFoj and wR Fo2
¼
w
F2o ꢁ F2c
=
w
Fc2
:
a
4.1.4. Synthesis of reduced Schiff base macrocycle 2b
4.2.3. Synthesis of complex 9
To a suspension of 1c (662 mg, 1 mmol) in 50 mL of ethanol was
added sodium borohydride in excess and the reaction mixture re-
fluxed for 5 h. Then it was cooled, quenched with water (50 mL)
and extracted with dichloromethane (50 mL ꢂ 2). The organic
phase was dried over anhydrous sodium sulphate, filtered and con-
centrated to give a white solid. It was recrystallized from CHCl3/
CH3CN (1:1). Yield: 450 mg, 68%; mp 162–164 °C. Anal. Calc. for
Ligand 2c (174 mg, 0.24 mmol) was dissolved in 35 mL of meth-
anol at ambient temperature. To this an equimolar mixture of
HgCl2 and NH4PF6 (0.48 mmol each) in 10 mL of methanol was
added to give a white precipitate. It was stirred for 30 min, filtered
under vacuum, washed with methanol and dried under vacuum. X-
ray quality crystals were obtained from the mother liquor. Yield:
290 mg, 81%; mp 205–207 °C. Anal. Calc. for C36H46Cl2F12Hg2N6
P2Se2: C, 29.16; H, 3.13; N, 5.67. Found: C, 26.74; H, 2.62; N,
5.74%. 77Se NMR (CD3CN): d 299, 1180. IR(cmꢁ1): 3213, 1588,
842, 562.
C34H40N4Se2: C, 61.63; H, 6.08; N, 8.46. Found: C, 62.05; H, 5.25;
N, 8.34%. 1H NMR (CDCl3): d 1.68 (q, 4H, CH2CH2CH2), 2.70 (t, 8H,
NHCH2CH2), 3.85 (s, 8H, ArCH2NH), 7.08 (t, 4H, J = 7.5 Hz), 7.19
(dd, 4H, J = 7.3 Hz), 7.24 (dd, J = 7.7 Hz), 7.33 (dd, 4H, J = 7.5 Hz).
13C NMR (CDCl3): d 30.09 (CH2CH2CH2), 47.94 (NH2CH2CH2),
127.49, 128.08, 129.75, 132.98, 134.30, 141.78 (aromatic C). 77Se
NMR(CDCl3): d 326. MALDI-TOF: m/e 663 (M+). IR(cmꢁ1): 3299,
3230, 1583, 1562.
4.3. Crystal structure determination of 3, 4, 5, 2b and 9
The diffraction measurements for 3 and 4 were performed at
room temperature whereas 5, 2b and 9 were performed at
200(2) K, 223 K and 103(2) K, respectively on an Oxford Diffraction
Gemini diffractometer with Cu K
with graphite-monochromated Mo K
a
radiation (k = 1.54184 Å) (3) and
radiation (k = 0.71073 Å) (4,
4.2. Syntheses of complexes
a
5, 2b and 9). The data were corrected for Lorentz, polarization and
absorption effects. The structures were determined by routine hea-
vy-atom methods using SHELXS 97 [12] and Fourier methods and re-
fined by full-matrix least squares with the non-hydrogen atom
anisotropic and hydrogen with fixed isotropic thermal parameters
of 0.07 Å2 by means of the SHELXL 97 [13] program. The hydrogens
were partially located from difference electron-density maps, and
the rest were fixed at predetermined positions. Scattering factors
were from common sources [14]. Some details of the data collec-
tion and refinement are given in Table 6.
4.2.1. Synthesis of complex 7
To a methanolic solution (20 mL) of 6 (135 mg, 0.3 mmol), Ag-
ClO4ꢀxH2O (62 mg, 0.3 mmol) was added and the mixture stirred
at room temperature for 30 min. A pinkish white precipitate ap-
peared after 15 min. The reaction mixture was further stirred for
15 min. The precipitate was then filtered, washed with methanol
and dried under vacuum. Yield: 90 mg, 45%, mp 195–197 °C. Anal.
Calc. for C19H25F12AgClN3O4Se2: C, 34.54; H, 3.81; N, 6.36. Found: C,
34.48; H, 3.42; N, 6.46%. 77Se NMR (CD3CN): d 424. IR(cmꢁ1): 3268,
1560.
5. Supplementary material
4.2.2. Synthesis of complex 8
CCDC 763923, 763924, 763925, 763926 and 148628 contain the
supplementary crystallographic data for this paper. These data can
be obtained free of charge from The Cambridge Crystallographic
Data Centre via www.ccdc.cam.ac.uk/data_request/cif.
To a methanolic solution (20 mL) of 2b (200 mg, 0.3 mmol),
Hg(OAc)2 (191 mg, 0.6 mmol) was added and the reaction mixture
refluxed for 30 min. Then NH4PF6 was added in excess to afford a
white precipitate. The reaction mixture was refluxed for 15 min.
more. It was filtered, washed with methanol and dried under vac-
uum. Yield: 322 mg, 79%, mp 189–191 °C. Anal. Calc. for
Acknowledgements
C
34H40F12Hg2N4P2Se2: C, 30.17; H, 2.98; N, 4.14. Found: C, 30.42;
We are thankful to the Department of Science and Technology
(DST), India for funding this work. Additional help from the Sophis-
ticated Analytical Instrument Facility (SAIF), Indian Institute of
H, 2.73; N, 4.61%. 77Se NMR (CD3CN): d 313. IR(cmꢁ1): 3259,
1584, 839, 558.

T. Chakraborty et al. / Inorganica Chimica Acta 363 (2010) 2905–2911
2911
(b) W. Levason, J.M. Manning, M. Nirwan, R. Ratnani, G. Reid, H.L. Smith, M.
Webster, Dalton Trans. (2008) 3486. and references cited therein.
[5] S. Muralidharan, M. Hojjatie, M. Firestone, H. Freiser, J. Org. Chem. 54 (1989)
393.
[6] R. Bhula, A.P. Arnold, G.J. Gainsford, W.G. Jackson, Chem. Commun. (1996) 143.
[7] (a) X. Wei, L. Xiufang, L. Xueran, X. Hansheng, Wuhan Univ. J. Nat. Sci. 2 (1997)
464;
Technology, Bombay, for 300 MHz NMR spectroscopy is gratefully
acknowledged. We gratefully acknowledge Dr. A. Panda for help in
the synthesis of the macrocyclic ligand 2b. T.C. and K.S. are also
grateful to the Council of Scientific and Industrial Research, India
for providing fellowship.
(b) X. Hansheng, X. Guangya, W. Jun, L. Xiufang, Wuhan Univ. J. Nat. Sci. 4
(1999) 85;
(c) Y. Liu, J.-R. Han, Y. Chen, A. Yu, Z.-Y. Duan, H.-Y. Zhang, Supramol. Chem. 17
(2005) 623;
References
(d) Y. Liu, J.-R. Han, Y.-L. Zhao, H.-Y. Zhang, Z.-Y. Duan, J. Inclusion Phenom.
Macrocyclic Chem. 51 (2005) 191.
[8] (a) A. Panda, S.C. Menon, H.B. Singh, R.J. Butcher, J. Organomet. Chem. 623
(2001) 87;
[1] (a) L.F. Lindoy (Ed.), The Chemistry of Macrocyclic Ligand Complexes,
Cambridge University Press, Cambridge, 1989;
(b) B. Dietrich, P. Viout, J.-M. Lehn, Macrocyclic Chemistry: Aspects of Organic
and Inorganic Supramolecular Chemistry, Wiley-VCH, Weinheim, 1993;
(c) J.-M. Lehn, Supramolecular Chemistry: Concepts and Perspectives, Wiley-
VCH, Weinheim, 1995;
(d) J.W. Steed, J.L. Atwood (Eds.), Supramolecular Chemistry, Wiley,
Chichester, 2000;
(b) S. Panda, H.B. Singh, R.J. Butcher, Chem. Commun. (2004) 322;
(c) S. Panda, H.B. Singh, R.J. Butcher, Inorg. Chem. 43 (2004) 8532;
(d) A. Panda, S.C. Menon, H.B. Singh, C.P. Morley, R. Bachman, T.M. Cocker, R.J.
Butcher, Eur. J. Inorg. Chem. 6 (2005) 1114;
(e) S. Panda, H.B. Singh, R.J. Butcher, Eur. J. Inorg. Chem. 7 (2006) 172;
(f) U. Patel, H.B. Singh, R.J. Butcher, Eur. J. Inorg. Chem. 7 (2006) 5089.
[9] (a) S. Panda, S.S. Zade, H.B. Singh, G. Wolmershäuser, J. Organomet. Chem. 690
(2005) 3142;
(b) L. Syper, J. Mlochowski, Tetrahedron 44 (1988) 6119.
[10] S. Kumar, S. Panda, H.B. Singh, G. Wolmershäuser, R.J. Butcher, Struct. Chem.
18 (2007) 127.
[11] A. Bondi, J. Phys. Chem. 68 (1964) 441.
[12] G.M. Sheldrick, SHELXS 97, Program for the Solution of Crystal Structures,
University of Göttingen, Germany, 1990.
(e) H. Dodziuk, Introduction to Supramolecular Chemistry, Kluwer Academic
Pub., Dordrecht, 2002.
[2] (a) W. Levason, S.D. Orchard, G. Reid, Coord. Chem. Rev. 225 (2002) 159;
(b) A. Panda, Coord. Chem. Rev. 253 (2009) 1056.
[3] (a) R.J. Batchelor, F.W.B. Einstein, I.D. Gay, J.H. Gu, B.D. Johnston, B.M. Pinto, J.
Am. Chem. Soc. 111 (1989) 6582;
(b) R.J. Batchelor, F.W.B. Einstein, I.D. Gay, J.H. Gu, B.D. Johnston, B.M. Pinto,
X.M. Zhou, J. Am. Chem. Soc. 112 (1990) 3706;
(c) R.J. Batchelor, F.W.B. Einstein, I.D. Gay, J. Gu, S. Mehta, B.M. Pinto, X.M.
Zhou, Inorg. Chem. 35 (1996) 3667;
(d) R.J. Batchelor, F.W.B. Einstein, I.D. Gay, J.H. Gu, S. Mehta, B.M. Pinto, X.M.
Zhou, Inorg. Chem. 39 (2000) 2558.
[13] G.M. Sheldrick, SHELXL 97, Program for Refining Crystal Structures, University of
Göttingen, Germany, 1997.
[14] D.T. Cromer, J.T. Waber, International Tables for X-ray Crystallography, vol. IV,
Kynoch Press, Birmingham, 1974. p. 99, 149.
[4] (a) W. Levason, J.M. Manning, P. Pawelzyk, G. Reid, Eur. J. Inorg. Chem. (2006)
4380;