Synthesis, characterization and extraction studies of a new vic-dioxime and its complexes containing bis(diazacrown ether) moieties

Article abstract of DOI:10.1016/j.poly.2006.05.023

A new vicinal dioxime ligand containing bis(diazadioxa-12-crown-4 ethoxy) units (H₂L) has been synthesized by the reaction of cyanogendi-N-oxide with 3,4-bis(2-{10-[(4-methylphenyl)sulfonyl]-1,7-dioxa-4,10-diazacyclododecan-4-yl}ethoxy)aniline, which was prepared by the reduction of 4-[(4-methlyphenyl)sulfonyl]-10-[2-((4-nitro-2-{2-[10-phenylsulfonyl)-1,7-dioxa-4,10-diazacyclododecan-4-yl]ethoxy}phenoxy)ethyl]-1,7dioxa-4,10-diazacyclododecan. A mononuclear nickel(II) and copper(II) complexes with a metal:ligand ratio of 1:2 for H₂L were also synthesized. The mononuclear cobalt(III) complex of H₂L has been isolated with L′ = pyridine, together with chlorine as an axial ligand. In addition, a cobalt(III) complex containing the BF₂⁺ bridge macrocycle was synthesized using a precursor hydrogen-bridged cobalt(III) complex via the template effect. The extraction abilities of 1, 3, 6 and 10 were also evaluated in 1,2-dichloroethane by using several alkali (Li⁺, Na⁺, K⁺, Cs⁺) and transition metal picrates such as Ag⁺, Pb²⁺, Cd²⁺, Cu²⁺, Zn²⁺. The structure of the dioximes and their complexes are proposed according to elemental analyses, ¹H and ¹³C NMR, FT-IR UV-Vis and mass spectra.

Full text of DOI:10.1016/j.poly.2006.05.023

Polyhedron 25 (2006) 3165–3172
www.elsevier.com/locate/poly
Synthesis, characterization and extraction studies of a new
vic-dioxime and its complexes containing bis(diazacrown ether) moieties
a,
b
b
c
b
*
˘
˘
Ahmet Bilgin , Beytullah Ertem , Fatma Dinc¸ Agın , Yaßsar Go¨k , Selami Karslıoglu
a
Department of Science Education, Kocaeli University, 41300 Kocaeli, Turkey
Department of Chemistry, Karadeniz Technical University, 61080 Trabzon, Turkey
Department of Chemistry, Pamukkale University, Kınıklı Campus 20070 Kınıklı/Denizli, Turkey
b
c
Received 3 April 2006; accepted 16 May 2006
Available online 6 June 2006
Abstract
A new vicinal dioxime ligand containing bis(diazadioxa-12-crown-4 ethoxy) units (H2L) has been synthesized by the reaction of cya-
nogendi-N-oxide with 3,4-bis(2-{10-[(4-methylphenyl)sulfonyl]-1,7-dioxa-4,10-diazacyclododecan-4-yl}ethoxy)aniline, which was pre-
pared by the reduction of 4-[(4-methlyphenyl)sulfonyl]-10-[2-((4-nitro-2-{2-[10-phenylsulfonyl)-1,7-dioxa-4,10-diazacyclododecan-4-
yl]ethoxy}phenoxy)ethyl]-1,7dioxa-4,10-diazacyclododecan. A mononuclear nickel(II) and copper(II) complexes with a metal:ligand
ratio of 1:2 for H2L were also synthesized. The mononuclear cobalt(III) complex of Hþ2L has been isolated with L0 = pyridine, together
with chlorine as an axial ligand. In addition, a cobalt(III) complex containing the BF2 bridge macrocycle was synthesized using a pre-
cursor hydrogen-bridged cobalt(III) complex via the template effect. The extraction abilities of 1, 3, 6 and 10 were also evaluated in 1,2-
dichloroethane by using several alkali (Li+, Na+, K+, Cs+) and transition metal picrates such as Ag+, Pb2+, Cd2+, Cu2+, Zn2+. The struc-
1
ture of the dioximes and their complexes are proposed according to elemental analyses, H and 13C NMR, FT-IR UV–Vis and mass
spectra.
ꢀ 2006 Elsevier Ltd. All rights reserved.
þ
Keywords: vic-Dioxime; Bis(diazacrown ethers); Cobalt(III) complex; Template effect; BF2 capped complex; Extraction
1. Introduction
selectivities towards certain cations as compared to the cor-
responding monocycles analogues [2,3]. On the other hand,
bis(diazacrown ether) compounds have also been used as
carriers in transport experiments, giving rise to different
selectivities and efficiencies. This behaviour can be related
to the strong effect of the stability of the cation carrier com-
plex on the transport efficiency [4,5].
The chemistry of vic-dioximes and their numerous tran-
sition metal complexes have been widely investigated as
analytical reagents [6–8], models for biological systems
such as vitamin B12 [9], and compounds having columnar
stacking which is thought to be reason for their semicon-
ducting properties [10]. The exceptional stability and
unique electronic properties of these complexes can be
attributed to their planar structure, stabilized by hydrogen
bonding. In recent years, such attention has been given to
polynuclear metal complexes because of their role in
The topology of macrocyclic polyethers strongly con-
tributes to their cation complexation. The use of bicyclic
structures is an attractive strategy to enhance cation com-
plexing abilities and selectivities of monocyclic diazacrown
ethers. Macrobicyclic polyethers carrying two diazacrown
ether moieties at the end of a spacer possess different com-
plexing properties [1]. Usually, these bis(diazacrown ethers)
are more likely to form intramolecular sandwich-type com-
plexes with certain cations that are a little larger than the
crown ring cavities by means of a cooperative action of
two adjacent diazacrown rings. As a result of such a com-
plex formation, the bis(diazacrown ether) exhibits excellent
*
Corresponding author. Tel.: +90 262 3032438; fax: +90 262 3032403.
E-mail address: abilgin@kou.edu.tr (A. Bilgin).
0277-5387/$ - see front matter ꢀ 2006 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2006.05.023

3166
A. Bilgin et al. / Polyhedron 25 (2006) 3165–3172
certain biological systems and their potential to act as mul-
tielectron redox catalysts [11–14]. Some novel studies have
been exploring a group of macrocyclic dioxime complexes
of Co(III) in which the bridging protons of the bis-dioxime
3.81 mmol) and 70 mL dry acetonitrile were added to a
three-necked flask fitted with a condenser which was evac-
uated, refilled three times with argon, and connected to a
vacuum line. Under argon, the mixture was stirred at
45 ꢁC for 30 min. Compound 2 (1.764 g, 3.81 mmol) was
added to this mixture under argon and the reaction mixture
was heated and stirred at 95 ꢁC for 7 days. The reaction
mixture was cooled to room temperature and filtered off
and the precipitated salt was washed with 25 mL dichloro-
methane. The major liquor and washing solvents were
combined and evaporated and a pale yellow solid-oily
crude was obtained. The residue was purified in a silica
gel column using chloroform:petroleum ether:methanol
(7:2:1) as eluents. The second fraction was combined and
evaporated, 10–15 mL methanol was added and the mix-
ture was stirred at room temperature for 30 min. The pre-
cipitated pale yellow crystals were filtered off and dried in
vacuo.
þ
ligands have been replaced by BF2 groups, an alteration
that firms up the macrocyclic structure while removing
acidic protons from the vicinity of the O2 binding site
[15–17].
In this work the synthesis and characterization of a
(E,E)-dioxime containing bis(diazadioxa-12-crown-4 eth-
oxy) units and Ni(II), Cu(II) and Co(III) complexes of
H2L are reported. A cobalt(III) complex containing the
þ
BF2 bridge macrocycle is synthesized as well. In addition,
alkali and heavy metal extraction abilities of 1, 3, 6 and 10
are also examined.
2. Experimental
2.1. Materials
Compound 3: Yield: 2.92 g (89%); m.p. 190–192 ꢁC.
Anal. Calc. for C40H57N5O12S2: C, 55.62; H, 6.60; N,
8.11. Found: C, 55.25; H, 6.47; N, 8.22%. IR (KBr): mmax
(cmꢀ1): 3087, 3027, 2919–2851, 1597, 1587–1338, 1514–
1,2-Bis(2-hydroxyethoxy)benzene [18], 1,2-bis(2-chloro-
ethoxy)benzene [19], 1,2-bis(2-chloroethoxy)-4-nitroben-
zene [20], 1,2-bis(2-iodoethoxy)-4-nitrobenzene [20], 6-[(4-
methylphenyl)sulfonyl]-3,9-dioxa-6-aza-1,11-undecandiol-
bis(methanesulfanate) [21], benzyl-4-[(4-methylphenyl)sul-
1
1453, 1275–1229, 1160–1019. H NMR (CDCl3): d 8.01
(d, 1H, Ar–H), 7.84 (s, 1H, Ar–H), 7.32 (d, 1H, Ar–H),
7.61 (d, 4H, Ar–H), 6.90 (d, 4H, Ar–H), 4.52–4.40 (m,
4H, Ar–O–CH2), 4.13-3.95 (m, 4H, –CH2N), 3.76–3.52
(m, 16H, CH2CH2OCH2CH2), 3.18–2.80 (m, 16H,
CH2N), 2.36 (s, 6H, Ar–CH3). 13C NMR (CDCl3): d
154.05 (ArCO), 148.12 (ArCS), 143.29 (ArCH), 141.25
(ArCN), 135.67, 129.68, 127.2, 117.93, 111.12, 107.72
(ArC), 70.25–69.75 (OCH2), 56.08–55.06–60.63 (NCH2),
21.5 (CH3–Ar). MS (FAB positive): m/z 863 [M]+.
fonyl]-1,7-dioxa-4,10-diazacyclododecan
[21],
4-[(4-
methylphenyl)sulfonyl]-1,7-dioxa-4,10-diazacyclododecan
[21] and cyanogen di-N-oxide [22] were prepared according
to the literature procedures. Reagent grade chemicals were
used as received. Solvents were purified according to stan-
dard methods [23] before use. Silica gel (70–230 mesh) was
used for chromatographic separations.
2.2. Measurements
2.3.2. 3,4-Bis(2-{10-[(4-methylphenyl)sulfonyl]-1,7-dioxa-
4,10-diazacyclododecan-4-yl}ethoxy)aniline (4)
Melting points were determined using an electrothermal
Compound 3 (2.92 g, 3.38 mmol) was dissolved in
120 mL n-butanol at 60 ꢁC under an argon atmosphere
and degassed in a vacuum line. 0.417 g Pd/C (10%) was
added to the reaction mixture and heated at 125 ꢁC. At
reflux temperature, 5.96 mL hydrazinium hydrate (100%)
was added to this mixture dropwise over 30 min. After
14 h, the reaction mixture was filtered off using Celite as
the filtering agent and washed several times with n-butanol.
The major liquor and washing solvents were combined and
evaporated to dryness under reduced pressure. Diethyl
ether was added to the residue under argon and the result-
ing solution was kept in darkness, otherwise the amino
derivative can decompose. A little amount of the amino
derivative 4 was kept to take its IR, 1H NMR, 13C
NMR, elemental analysis and mass spectra. Compound 4
was used for the following reaction without any further
purification.
1
apparatus and were uncorrected. The H and 13C NMR
spectra were recorded on a Varian XL-200 spectrometer
and IR spectra were recorded on a Perkin–Elmer Spectrum
One spectrometer with the samples in KBr pellets. The
UV–Vis spectra were recorded on a model Schimadzu
1601 UV–Vis spectrometer using a 1 cm pathlength quartz
UV-cell. Fast atom bombardment mass spectra were
recorded on a Varian MAT 711 and VG Zap Spec spec-
trometers using m-nitrobenzyl alcohol as the matrix. The
elemental analysis and the metal contents of the com-
pounds were determined on a Hewlett-Packard 185 CHN
analyzer and on a Unicam 929 AA spectrophotometer.
2.3. Synthesis
2.3.1. 4-[(4-Methlyphenyl)sulfonyl]-10-[2-((4-nitro-2-{2-
[10-phenylsulfonyl)-1,7-dioxa-4,10-diazacyclododecan-4-
yl]ethoxy}phenoxy)ethyl]-1,7-dioxa-4,10-
diazacyclododecan (3)
Finely ground anhydrous Na2CO3 (4.0 g, 3.81 mmol),
compound 1 (2.5 g, 7.62 mmol), anhydrous NaI (0.572 g,
Compound 4: Yield: 2.32 g (84%); m.p. 128–131 ꢁC.
Anal. Calc. for C40H59N5O10S2: C, 57.62; H, 7.08; N,
8.40. Found: C, 57.40; H, 6.98; N, 8.57%. IR (KBr): mmax
(cmꢀ1): 3439–3362, 3060–3032, 2924–2856, 1621, 1597,
1
1511–1448, 1303–1225, 1159–1019. H NMR (CDCl3): d

A. Bilgin et al. / Polyhedron 25 (2006) 3165–3172
3167
6.95 (d, 1H, Ar–CH–C–O), 6.72 (s, 1H, Ar–N–CH–C–O),
6.35 (d, 1H, Ar–NH2–C–CH), 7.58 (d, 4H, Ar–SO2–C–
CH), 6.76 (d, 4H, H3C–AR–CH), 4.57 (br, s, 2H, NH2),
4.48–4.36 (m, 4H, Ar–O–CH2), 4.01–3.87 (m, 16H,
CH2CH2OCH2CH2), 3.72–3.46 (m, 4H, –CH2N), 3.15–
2.72 (m, 16H, CH2N), 2.34 (s, 6H, Ar–CH3). 13C NMR
(CDCl3): d 146.12 (ArCO), 143.36 (ArCS), 141.03 (ArCH),
138.11 (ArCN), 135.72, 129.65, 127.10, 108.22, 102.50
(ArC), 70.27–69.70–67.45 (OCH2), 56.08–55.04–50.59
(NCH2), 21.5. MS (FAB positive): m/z 833 [M]+.
Ar–CH), 6.88 (d, 4H, Ar–CH–C–O), 6.43 (s, 4H, Ar–N–
CH–C–O), 6.21 (d, 4H, Ar–NH–C–CH), 4.40–4.32
(m,16H,
Ar–O–CH2),
3.92–3.78
(m,
64H,
CH2CH2OCH2CH2), 3.67–3.39 (m, 16H, –CH2N), 3.09–
2.63 (m, 64H, CH2N), 2.37 (s, 24H, Ar–CH3). MS (FAB
positive): m/z 3556 [M+1]+.
2.3.5. [Cu(HL)2] (8)
A solution of CuCl2 Æ 2H2O (9 mg, 0.05 mmol) in 5 mL
ethanol was added to a solution of H2L 6 (175 mg, 1 mmol)
in 25 mL ethanol at 60 ꢁC. A distinct change in color and a
decrease in the pH of the solution (pH 2.38) was observed.
While heating and stirring at the same temperature, an
equivalent of ethanolic triethylamine (0.1 M) was added
in order to increase the pH to 5.0–6.0. After heating the
reaction mixture for 2 h in a water-bath, the precipitate
was filtered off, washed several times with water, ethanol
and diethyl ether and then dried in vacuo by P2O5.
Compound 8: Yield: 136 mg (76%); m.p. >300 ꢁC. Anal.
Calc. for C164H234N24O44S8: C, 55.26; H, 6.27; N, 9.43; Cu,
1.78. Found: C, 55.19; H, 6.13; N, 9.56; Cu, 1.63%. IR
(KBr): mmax (cmꢀ1): 3389, 3054–3021, 2920–2881, 1733,
1624, 1598, 1508–1446, 1303–1220, 1160–1020, 941. MS
(FAB positive): m/z 3561 [M+1]+.
2.3.3. H2L (6)
A cold solution, ꢀ10 ꢁC, of cyanogen di-N-oxide (5) in
25 mL dichloromethane, which was prepared from (E,E)-
dichloroglyoxime (0.785 g, 5 mmol), and 25 mL of an
aqueous solution at ꢀ10 ꢁC of 0.5 M Na2CO3 was added
to a cold solution of 3,4-bis(2-{10-[(4-methylphenyl)sulfo-
nyl]-1,7-dioxa-4,10-diazacyclododecan-4-yl}ethoxy)aniline
4 (2.36 g, 2.8 mmol) in 200 mL dichloromethane. The reac-
tion was continued for 10–12 h at the same temperature
and then evaporated to dryness. The crude product was
crystallized from a dichloromethane:ethanol mixture (9:1)
to yield champagne colored crystals.
Compound 6: Yield: 1.54 g (62%); mp 154–156 ꢁC (dec).
Anal. Calc. for C82H118N12O22S4: C, 56.23; H, 6.74; N,
9.60. Found: C, 56.09; H, 6.52; N, 9.76%. IR (KBr): mmax
(cmꢀ1): 3350, 3230, 3082-3042, 2922-2868, 1640, 1611,
1596, 1514–1448, 1289–1228, 1160–1020, 942. 1H NMR
(DMSO-d6): d 10.20 (s, 2H, OH), 7.86 (s, 2H, NH), 7.60
(d, 8H, Ar–SO2–C–CH), 6.78 (d, 8H, H3C–Ar–CH), 6.92
(d, 2H, Ar–CH–C–O), 6.49 (s, 2H, Ar–N–CH–C–O), 6.25
(d, 2H, Ar–NH–C–CH), 4.45–4.34 (m, 8H, Ar–O–CH2),
3.98-3.82 (m, 32H, CH2CH2OCH2CH2), 3.69–3.42 (m,
8H, –CH2N), 3.14–2.71 (m, 32H, CH2N), 2.35 (s, 12H,
Ar–CH3). 13C NMR (CDCl3): d 154.09, 148.17, 145.02
(C@N–O–H), 143.25, 141.30, 135.69, 129.68, 127.15,
117.95, 111.12, 107.80, 70.29, 69.77, 67.53, 56.10, 55.04,
50.61, 21.5. MS (FAB positive): m/z 1750 [M]+.
2.3.6. [Co(HL)2L0Cl] (9)
A solution of CoCl2 Æ 6H2O (24 mg, 0.1 mmol) in 10 mL
ethanol was added to a solution of H2L 6 (350 mg, 2 mmol)
in 75 mL ethanol at 60 ꢁC whilst bubbling oxygen through
the ligand solution. After 30 min, 0.01 mL pyridine (0.01 g,
0.1 mmol) in 5 mL ethanol was added to the mixture. The
reaction mixture was heated and stirred for 4–5 h with oxy-
gen passing through it. The total volume of the residue was
decreased to 1/4 and then filtered off, washed several times
with water, ethanol and diethyl ether and then dried in
vacuo by P2O5.
Compound 9: Yield: 206 mg (56%); m.p. >300 ꢁC. Anal.
Calc. for C169H239N25O44S8CoCIPy: C, 55.24; H, 6.51; N,
9.53; Co, 1.59. Found: C, 55.17; H, 6.38; N, 9.47; Co,
1.50%. IR (KBr): mmax (cmꢀ1): 3325, 3070, 3063–3025,
2924–2870, 1722, 1621, 1597, 1601, 1549–1510, 1286–
2.3.4. [Ni(HL)2] (7)
A solution of NiCl2 Æ 6H2O (12 mg, 0.05 mmol) in 5 mL
ethanol was added to a solution of H2L 6 (175 mg, 1 mmol)
in 25 mL ethanol at 60 ꢁC. A distinct change in color and a
decrease in the pH of the solution (pH 2.42) was observed.
While heating and stirring at the same temperature, an
equivalent of ethanolic triethylamine (0.1 M) was added
in order to increase the pH to 4.5–5.0. After heating the
reaction mixture for 2 h in a water-bath, the precipitate
was filtered off, washed several times with water, ethanol
and diethyl ether and then dried in vacuo by P2O5.
Compound 7: Yield: 146 mg (82%); m.p. >300 ꢁC. Anal.
Calc. for C164H234N24O44S8Ni: C, 55.34; H, 6.58; N, 9.45.
Found: C, 55.13; H, 6.35; N, 9.54%. IR (KBr): mmax
(cmꢀ1): 3392, 3060–3018, 2923–2865, 1718, 1627, 1618,
1597, 1506–1449, 1286–1220, 1159–1020, 946. 1H NMR
(DMSO-d6): d 16.80 (s, 2H, O–Hꢁ ꢁ ꢁO), 7.98 (br, s, 4H,
NH), 7.58 (d, 16H, Ar–SO2–C–CH), 6.73 (d, 16H, H3C–
1
1226, 1159–1020, 943. H NMR (DMSO-d6): d 16.85 (s,
2H, O–Hꢁ ꢁ ꢁO), 8.02 (br, s, 4H, NH), 7.71 (d, 2H, py-H),
7.50 (t, 2H, py-H), 6.84 (t, 1H, py-H), 7.60 (d, 16H, Ar–
SO2–C–CH), 6.79 (d, 16H, H3C–Ar–CH), 6.84 (d, 4H,
Ar–CH–C–O), 6.42 (s, 4H, Ar–N–CH–C–O), 6.21 (d, 4H,
Ar–NH–C–CH), 4.42–4.31 (m, 16H, Ar–O–CH2), 3.94–
3.76 (m, 64H, CH2CH2OCH2CH2), 3.65–3.37 (m, 16H, –
CH2N), 3.11–2.65 (m, 64H, CH2N), 2.35 (s, 24H, Ar–
CH3). MS (FAB positive): m/z 3671 [M+1]+.
2.3.7. [Co(LBF2)2L0Cl] (10)
A suspension of the diamagnetic cobalt (III) complex
[Co(HL)2L0Cl] 9 (0.734 g, 0.2 mmol) in 100 mL of freshly
distilled acetonitrile was brought to reflux temperature
under an argon atmosphere. The equivalent amount of
BF3 Æ OEt2 (0.1 mL, 0.4 mmol) was added to the above

3168
A. Bilgin et al. / Polyhedron 25 (2006) 3165–3172
suspension and the reaction mixture became red immedi-
ately. The solution was boiled under reflux with stirring
for 5 h and then allowed to cool to room temperature.
The solvent was concentrated to 10 mL under reduced
pressure; 20 mL of dry Et2O was then added dropwise
and the solution was allowed to stand at ꢀ18 ꢁC overnight,
whereupon the desired product precipitated. The claret red
solid was collected by filtration, washed with cold acetoni-
trile and Et2O and then dried in vacuo.
Compound 10: Yield: 512 mg (68%); m.p. >300 ꢁC. Anal.
Calc. for C169H237N25O44S8CoClB2F4: C, 53.84; H, 6.29;
N, 9.29; Co, 1.56. Found: C, 54.65; H, 6.78; N, 9.02, Co,
1.32%. IR (KBr): mmax (cmꢀ1): 3336, 3068, 3060–3022,
2950–2863, 1649, 1590, 1605, 1545–1510, 1284–1223,
1156–1030, 948, 875–843. 1H NMR (DMSO-d6): d 7.96
(br, s, 4H, NH), 7.68 (d, 2H, py-H), 7.47 (t, 2H, py-H),
6.80 (t, 1H, py-H), 7.59 (d, 16H, Ar–SO2–C–CH), 6.75
(d, 16H, H3C–Ar–CH), 6.81 (d, 4H, Ar–CH–C–O), 6.41
(s, 4H, Ar–N–CH–C–O), 6.19 (d, 4H, Ar–NH–C–CH),
4.39–4.27 (m, 16H, Ar–O–CH2), 3.92–3.70 (m, 64H,
CH2CH2OCH2CH2), 3.64–3.35 (m, 16H, –CH2N), 3.13–
2.64 (m, 64H, CH2N), 2.38 (s, 24H, Ar–CH3). MS (FAB
positive): m/z 3768 [M+1]+, 3785 [M+H2O]+ and 3686
[Mꢀpyr-2]+.
samples and the average value of percent picrate extracted,
with a standard deviation, was calculated. The picrate
extraction results are presented in Table 1. In the absence
of host, a blank experiment, no metal ion picrate extraction
was detected. The extractability was determined based on
the absorbance of the picrate ion in the aqueous solutions.
The extractability was calculated by using the equation
below:
Eð%Þ ¼ ½ðAbefore ꢀ AafterÞ=Abeforeꢃ ꢄ 100
where Abefore is the absorbance in the absence of ligand.
Aafter denotes the absorbance in the aqueous solution phase
after extraction.
3. Results and discussion
The synthesis of the nitro derivative 3 was performed by
starting with 1,2-bis(2-iodoethoxy)-4-nitrobenzene (2) [20]
and 4-[(4-methylphenyl)sulfonyl]-1,7-dioxa-4,10-diazacy-
clododecan (1) [21] in acetonitrile in the presence of
anhydrous Na2CO3 and NaI for a period of 7 days,
affording 4-[(4-methlyphenyl)sulfonyl]-10-[2-((4-nitro-2-{2-
[10-phenylsulfonyl)-1,7-dioxa-4,10-diazacyclododecan-4-yl]
ethoxy}phenoxy)ethyl]-1,7-dioxa-4,10-diazacyclododecan
(3) (Scheme 1). The template effect of sodium cations
accounts for the high yield obtained in the desired synthesis.
Final purification of the nitro derivative 3 by chromatogra-
phy [silica gel, chloroform:petroleum ether:methanol
(7:2:1)] afforded 3 in 89% yield, for which elemental analysis
and FAB mass spectral data were satisfactory: 863 [M]+. In
the 1H NMR spectrum of 3, the NH group of compound 1
disappeared as expected. It can also be observed in its IR
spectrum, confirming the formation of compound 3. The
NO2 functional group also can be seen at 1587–1338 cmꢀ1
in the IR spectrum of compound 3.
2.3.8. Measurement of alkali and heavy metal-binding
properties of 1, 3, 6 and 10
The extraction properties of 1, 3, 6 and 10 were investi-
gated under liquid–liquid phase and neutral conditions
using alkaline (Li+, Na+, K+, Cs+) and heavy metal
picrates (Ag+, Pb2+, Cd2+, Cu2+, Zn2+) as substrates and
measuring by UV–Vis spectra the amounts of metal picrate
in the aqueous phase before and after treatment with the
compounds. Alkali metal picrates (3 · 10ꢀ5 M) were pre-
pared from a mixture of the alkali metal hydroxides and
picric acid in deionized water whereas the heavy metal
picrates were prepared from a mixture of the metal nitrates
and picric acid in deionized water. We also prepared
3 · 10ꢀ3 M solutions of the compounds (1, 3, 6, 10) in
1,2-dichloroethane. Then equal volumes of both metal pic-
rate solutions and compound solutions were added into
plastic bottles and kept closed then shaken for 12 h by a
shaker at 25 1 ꢁC. Finally we took the aqueous phase
and measured the absorbance at maximum wavelength
(ꢂ358 nm). For each combination of host and metal pic-
rate, the picrate extraction was conducted on three different
The transformation of the nitro derivative 3 into the
amino derivative 4 was performed in the presence of n-
butanol using hydrazinium hydrate (100%) and Pd/C
(10%) for 14 h with a 84% yield. Since this method is more
advantageous than the others, we preferred to use this one.
No further purification was performed for compound 4
when it was obtained because of the characteristic property
of so many amino derivatives that they decomposes very
1
easily when exposed to light and heat. H NMR spectrum
of 4 showed a new signal due to NH2 protons at d = 4.52,
as expected. It is possible to see the NH2 stretching vibra-
Table 1
Alkaline and heavy metal picrate extractions from aqueous solutions into 1,2-dichloroethane by using 1, 3, 6 and 10a
Host molecule
Percent of metal picrate extracted (%)b
Li+
Na+
K+
Cs+
Ag+
Zn2+
Cd2+
Cu2+
Pb2+
1
3
9.3 0.1
42.3 0.1
78.3 0.1
82.1 0.1
85.5 0.1
22.6 0.1
48.7 0.1
58.3 0.1
62.9 0.1
0.4 0.1
1.6 0.1
2.8 0.1
6.7 0.1
39.1 0.1
69.3 0.1
78.1 0.1
81.6 0.1
27.5 0.1
43.6 0.1
46.3 0.1
49.2 0.1
18.6 0.1
30.2 0.1
34.5 0.1
37.8 0.1
36.7 0.1
56.9 0.1
60.4 0.1
68.7 0.1
11.8 0.1
29.8 0.1
37.3 0.1
45.6 0.1
15.2 0.1
18.6 0.1
23.4 0.1
6
10
a
Temperature 25 1 ꢁC; aqueous phase (10 ml), [picrate] = 3.0 · 10ꢀ3 M; organic phase (1,2-dichloroethane, 10 ml), [host molecule] = 3.0· 10ꢀ3 M.
Average and standard deviation for three independent measurements.
b

A. Bilgin et al. / Polyhedron 25 (2006) 3165–3172
3169
O
O
O
O
S
H3C
S
N
N
N
N
H3C
N
N
N
N
n-Butanol
Ar(g)
Reflux
I
I
O
N
O
O
O
O
O
S
O
O
NO2
O
O
NO2
O
O
NH2
O
O
O
O
Na2CO3
CH3CN
Ar(g)
H C
3
N
N H
2
+
+
NH2 NH2
10% Pd/C
O
N
O
O
S
O
S
H3C
H3C
O
O
O
O
5
1
2
3
4
CH2Cl2
Ar(g)
-10 ºC
O
O
O
S
O
S
H
H3C
N
N
N
N
N
N
N
CH3
H
O
N
O
O
O
N
O
O
O
O
O
O
O
N
O
N
H
O
S
O
S
H3C
H3C
H3C
N
CH3
H
O
O
O
O
H2L
6
NiCl2.6H2O
or
Ethanol
60 ºC
CuCl2.2H2O
H3C
CH3
O
O
N
S
S
CH3
O
O
N
O
N
O
O
N
O
O
O
O
S
S
O
O
N
O
O
N
O
O
O
N
H
M
H
N
O
O
O
O
H
N
O
N
O
N
H
N
N
H
N
O
N
H
N
O
O
N
N
O
N
O
O
N
O
O
N
O
O
O
S
S
O
N
N
O
O
O
O
N
O
O
O
CH3
S
S
O
H3C
CH3
7 : Ni(II)
8 : Cu(II)
Scheme 1. Synthesis of H2L and its complexes [Ni(II),Cu(II)].
tions at 3439 and 3362 cmꢀ1 in the IR spectrum of com-
pound 4. In addition to this information, at 1621 cmꢀ1 in
the IR spectrum of compound 4 there is a peak belonging
to NH2 bending. Elemental analysis data was very satisfac-
tory and FAB mass spectral data was: 833 [M]+, as
expected.
The novel vic-dioxime 6 was synthesized from the reac-
tion of compound 4 and cyanogen di-N-oxide 5 at ꢀ10 ꢁC

3170
A. Bilgin et al. / Polyhedron 25 (2006) 3165–3172
in dichloromethane in the presence of an aqueous solution
for this complex too, with the pyridine and chlorine ligands
in axial positions of the octahedral complex, according to
elemental analysis data. That there is a singlet peak at
of Na2CO3 (ꢀ10 ꢁC) for a period of 10–12 h in 62% yield.
1
In the H NMR spectrum of 6 there are singlet signals at
1
d = 10.20 and d = 7.86 due to the hydroxy imino groups
and NH protons respectively which can be identified easily
owing to deuterium-exchangeable characteristics of these
protons. The singlet chemical shifts of the hydroxy imino
groups indicate that the structure of this novel oxime deriv-
ative is (E,E). That the diamino glyoxime has the s-trans
d = 10.20 in place of the OH functional group in the H
NMR spectrum of complex 9 indicates the existence of
intramolecular hydrogen bonds (O–Hꢁ ꢁ ꢁO) which can be
easily observed by the deuterium-exchange method. The
chemical shifts for pyridine at d = 7.71, 7.50 and 6.84 indi-
cates the existence of an octahedral complex 9. The stretch-
ing vibrations of the OH functional group at 3230 cmꢀ1 for
compound 6 disappeared and a new peak was observed at
1722 cmꢀ1 which indicates of the existence of intramolecu-
lar hydrogen bonds. A broad C@N stretching vibration of
compound 9 at 1621 cmꢀ1 is lower than the stretching
vibration of the oxime derivative 6 (1640 cmꢀ1) which
proves that the oxime ligand coordinates with Co(III).
All these data show that all the relevant groups participate
in the formation of the complex.
1
form was determined by H NMR and X-ray structural
analyses [24]. Therefore, the same structure can be pro-
posed for this new oxime derivative 6, too. A 13C NMR
spectrum is one of the most convenient ways to prove the
true structure of vic-dioximes, and in the 13C NMR spec-
trum of 6 a singlet peak at d = 145.02 belongs to hydroxy
imino groups. That only one resonance is displayed relat-
ing to carbon atoms of oxime indicates that the structure
of this novel oxime derivative 6 is of the (E,E)-dioxime for-
mation [25]. In the IR spectrum of compound 6 there are
NH, OH, C@N and NO stretching vibrations at 3350,
3230, 1640 and 942 cmꢀ1, respectively. Both C@N and
OH stretching vibration data are harmonious with other
oxime derivatives whose structures are of the s-formation
[26]. Furthermore, FAB mass spectral data was 1750
[M]+, proving that the structure is the same as the pro-
posed structure. Elemental analysis data displays that the
desired compound is synthesized as well.
The BF2-bridged cobalt(III) complex 10 was obtained in
high yield, 68%, at moderate dilution (0.2 mmol) from the
hydrogen-bridged cobalt(III) complex and boron trifluo-
ride etherate (0.4 mmol) linking reagent (Scheme 2). This
reagent readily reacts with the O–Hꢁ ꢁ ꢁÆÆO bridge in the pre-
cursor molecule, yielding an extremely stable compound
containing two O–BF2–O bridges, and the single mole of
the axial ligand pyridine was retained, according to 1H
NMR and IR spectra and elemental analysis data of
[Co(LBF2)2L0Cl]. In the IR spectrum of the BF2þ-capped
cobalt(III) complex, the C@N stretching region can be used
to distinguish between the dihydrogen-bridged compound
and the diboron-bridged compound. This BF2-macrocycle
exhibits upward shifts of ca. 35 cmꢀ1 due to the strong elec-
tron-withdrawing influence of the BF2 groups incorporated
The mononuclear Ni(II) and Cu(II) complexes
[Ni(HL)2] and [Cu(HL)2], 7 and 8, were prepared from
the oxime derivative 6 and with a stoichiometric amount
of NiCl2 Æ 6H2O and CuCl2.2H2O respectively, in the pres-
ence of ethanol (Scheme 1). FAB mass spectral data for the
compounds 7 and 8 were 3556 [M+1]+ and 3561 [M+1]+
respectively. Both elemental analysis and FAB mass spec-
tral data showed that the metal:ligand ratio is 1:2 for com-
pounds 7 and 8. In the IR spectra of compounds 7 and 8,
in the macrocycle. The weak and broad band at 1722 cmꢀ1
,
concerning O–Hꢁ ꢁ ꢁO in-plane deformation of the short
hydrogen bond, disappeared upon encapsulation of the
H-bonded complex, with the concomitant appearance of
peaks around 1156–1030 and 875–843 cmꢀ1 for the B–O
C@N stretching vibrations are at 1624 and 1627 cmꢀ1
,
respectively. That the C@N stretching vibrations of com-
pounds 7 and 8 are lower than the stretching vibration of
the oxime derivative 6 (1640 cmꢀ1) proved that the oxime
ligand coordinates with the Ni(II) and Cu(II) cations in
the N,N0 style. In addition, the disappearance of functional
groups relating to d OH and m OH for compound 6, at 1427
and 3230 cmꢀ1, indicates that intramolecular hydrogen
bonds form with a peak at 1733 cmꢀ1 for each complex.
That there is a singlet peak at d = 16.80 in place of the
OH functional group in the 1H NMR spectrum of the
square planar complex 7 indicates the existence of intramo-
lecular hydrogen bonds (O–Hꢁ ꢁ ꢁO) which can be easily
observed by the deuterium-exchange method.
The mononuclear Co(III) complex, [Co(HL)2PyCl] 9,
was prepared from ligand 6, pyridine and an equivalent
amount of CoCl2 Æ 6H2O in the presence of ethanol
(Scheme 2). Whilst the reaction proceeded, oxygen gas
was passed through the reaction mixture in order to oxidize
Co(II) to Co(III). The FAB mass spectral data for com-
pound 9 was 3671 [M+1]+. The metal:ligand ratio is 1:2
1
and B–F groups, respectively [27]. In the H NMR spec-
trum of the BF2þ-capped macrocycle, the deuterium
exchangeable hydrogen-bridged protons belonging to the
H-bonded pseudomacrocylic precursor cobalt(III) complex
are no longer present after the formation of the BF2 bridge
[28]. This BF2-bridged cobalt(III) complex is also con-
firmed by its fast atom bombardment mass spectrum,
which gives a molecular ion peak at m/z = 3768 [M+1]+.
3.1. Solvent extraction of alkali and heavy metal cations
The alkali and heavy metal ion binding properties of
the compounds having diaza-12-crown-4 units was esti-
mated by solvent extraction of alkali- and heavy metal
picrates from the aqueous to an organic phase (Table
1). For comparison, the values obtained under the same
conditions for N-tosyl-diazadioxa-12-crown-4 (1) are
included in Table 1. In addition to compounds 3 and 6,
since the introduction of BF2 groups to complex 9 leads

A. Bilgin et al. / Polyhedron 25 (2006) 3165–3172
3171
O
O
O
S
O
S
H
H
H
3C
N
N
N
N
N
N
N
N
CH3
H
N
O
N
O
O
O
O
O
O
O
O
O
O
N
O
N
H
O
S
O
S
3C
CH3
H
O
O
H2
6
L
O
O
CoC l2.6H2
Ethanol
60 ºC
O
Pyridine
O2(g)
H
3C
CH3
O
O
S
S
H3
C
CH3
O
O
N
O
O
N
O
O
N
N
O
O
O
S
S
O
O
N
O
O
N
N
O
O
O
N
H
O
O
O
O
H
O
N
H
N
O
L'
Co
Cl
N
N
N
H
N
O
N
H
N
O
O
N
N
O
N
O
O
N
H
O
O
O
O
S
S
O
N
N
O
N
O
N
O
O
O
O
O
H
3C
CH3
S
S
O
O
9 (L': Pyridine)
H3
C
CH3
CH3
CH3CN
H
3C
BF3O(CH2CH3
)
Ar(g)
2
Reflux
O
O
S
S
H3
C
CH3
O
O
N
O
N
O
O
N
N
O
O
O
O
S
S
O
O
N
O
O
O
N
O
O
F
O
N
F
O
N
N
B
N
O
O
O
O
H
N
H
N
L'
Co
Cl
N
H
N
O
F
N
H
N
O
F
O
N
N
O
N
O
O
N
B
O
O
O
O
S
S
O
N
N
O
N
O
N
O
O
O
O
O
H
3C
CH3
S
S
O
O
H
3C
CH3
10 (L':Pyridine)
Scheme 2. Synthesis of complexes 9 and 10.
to an increase in the solubility, in addition to the bulky
diazacrown units just the BF2-bridged cobalt(III) complex
10 among the other complexes was used as an extractant.
In the case of all the host compounds, it might be
expected that the capability of extraction of the lithium
ion would be the highest among the alkali metal cations
on comparing its size to the cavity size, as the diameter
of the lithium ion is much more compatible with 12-mem-
bered macrocyclic units. Nevertheless the extraction was
highest for the sodium ion due to the bis-crown effect.
Therefore the sodium cation forms a sandwich type com-
plex by binding between two diazacrown units with a
metal:ligand ratio of 1:2. The capability of extraction
for alkali metal cations increased with compounds 1, 3,
6 and 10. However this increase was not so noteworthy
as compared to the increase of the 12-membered macrocy-
clic units. This might be due to steric hindrance of the
bulky diaza-12-crown-4 units.
We were not able to find extraction studies in the liter-
ature with heavy metal cations for compounds containing
bis(diaza-12-crown-4) moieties. Therefore this work
caused us to investigate and perform such a kind of study.
However, there are some reports on the extracting proper-
ties of tricyclic compounds. According to these studies,

3172
A. Bilgin et al. / Polyhedron 25 (2006) 3165–3172
compounds having (diaza-12-crown-4) subunits can form
dinuclear complexes with silver(I), zinc(II) and copper(II).
They can also form mononuclear complexes with other
cations such as mercury(II), lead(II) and cadmium(II)
[29–31].
ities of bis(diaza-12-crown-4) moieties synthesized in this
work follow the order 10 > 6 > 3 > 1.
Acknowledgements
Aza-crown ethers form stable complexes with the Ag+
cation by replacement of O atoms with N atoms in crown
ether moieties [31]. As can be easily figured out from Table
1, Ag+ has the highest extracting capability by forming
M2L type complexes since there are more diaza-12-
crown-4 units which can coordinate with cations that have
a small cation diameter. Also the compounds having diaza-
12-crown-4 units form ML type complexes with cations
having a bigger cation diameter. It means there are less
diaza-12-crown-4 units per cation which is why their
extracting capabilities are low. The other important fact
obtained from the data in Table 1 is that the sodium and
silver picrate capabilities of host molecules are closely par-
allel. It might be attributed the similarity of the cation
diameters between Na+ and Ag+.
The cation binding properties of the ligands depend
upon different factors such as macrocyclic effect, cavity
size and the type and number of donor atoms. Also, it
is known that vic-dioximes form stable complexes with
transition metal cations. In the case of compound 6, an
increase concerning its extraction capability might be
expected with the investigated metal cations having both
oximes and macrocyclic groups for complexation. Since
there is no noteworthy increase in its extraction capabil-
ity, it is not remarkable in our work. This can be easily
seen when it is compared to compound 3 or 10. The num-
ber of macrocyclic groups from 3 to 6 increases. It is dif-
ficult to comment whether or not the increase in
extraction capability is the result of oxime groups or the
increase in the number of macrocyclic groups, but,
according to these data, we can conclude that the macro-
cyclic effect and the number of donor atoms are much
more effective than oxime groups.
This study was supported by The Scientific and Techni-
cal Research Council of Turkey (TUBITAK), Project
Number: TBAG-2453(104T065) (Ankara, Turkey) and
the Research Fund of Karadeniz Technical University,
Project Number: 2002.111.2.8 (Trabzon/Turkey). We are
also indebted to Dr. Ayhan C¸ elik (University of Edin-
burgh/England) for assistance with some spectral data.
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H2L containing bis(diaza-12-crown-4) moieties and its
complexes [Ni(II), Cu(II), Co(III) and BF2-briged Co(III)]
have been synthesized in good yields and characterized.
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