Synthesis and crystal structures of two isostructural cobalt(III) complexes [Co(C15H21N2O)(C8H 7O2)(N3)] and [Co(C15H 21N2O)(C8H7

Article abstract of DOI:10.1080/15533174.2011.568437

Two isostructural mononuclear cobalt(III) complexes, [Co(C ₁₅H₂₁N₂O)(C₈H₇O ₂)(N₃)] (1) and [Co(C₁₅H₂₁N ₂O) (C₈H₇O₂

Full text of DOI:10.1080/15533174.2011.568437

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Synthesis and Crystal Structures of Two Isostructural
Cobalt(III) Complexes [Co(C15H21N2O)(C8H7O2)(N3)]
and [Co(C15H21N2O)(C8H7O2)(NCS)]
Li-Jun Liu a
a Experimental Center , Linyi Normal University , Linyi Shandong, P. R. China
Published online: 25 May 2011.
To cite this article: Li-Jun Liu (2011) Synthesis and Crystal Structures of Two Isostructural Cobalt(III) Complexes
[Co(C15H21N2O)(C8H7O2)(N3)] and [Co(C15H21N2O)(C8H7O2)(NCS)], Synthesis and Reactivity in Inorganic, Metal-Organic, and
Nano-Metal Chemistry, 41:5, 531-534
To link to this article: http://dx.doi.org/10.1080/15533174.2011.568437
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Synthesis and Reactivity in Inorganic, Metal-Organic, and Nano-Metal Chemistry, 41:531–534, 2011
Copyright ꢀ Taylor & Francis Group, LLC
C
ISSN: 1553-3174 print / 1553-3182 online
DOI: 10.1080/15533174.2011.568437
Synthesis and Crystal Structures of Two Isostructural
Cobalt(III) Complexes [Co(C15H21N2O)(C8H7O2)(N3)] and
[Co(C15H21N2O)(C8H7O2)(NCS)]
Li-Jun Liu
Experimental Center, Linyi Normal University, Linyi Shandong, P. R. China
2-[1-(2-piperidin-1-ylethylimino)ethyl]phenol derived from 1-
(2-hydroxyphenyl)ethanoneand 2-piperidin-1-ylethylamine has
not been prepared. In this article, the author describes the syn-
thesis and characterization of two new isostructural cobalt(III)
complexes with the Schiff base and 2-acetylphenolate. The crys-
tal structures of the complexes have been investigated by single
crystal X-ray diffraction.
Two isostructural mononuclear cobalt(III) complexes,
[Co(C15H21N2O)(C8H7O2)(N3)] (1) and [Co(C15H21N2O)
(C8H7O2)(NCS)] (2), were synthesized and characterized by
elemental analysis, IR spectra, and X-ray single crystal structure
determination. X-ray structural analysis indicates that both
complexes crystallizing in the monoclinic space group P21/c, with
a = 13.190(2) Å, b = 12.842(2) Å, c = 18.428(2) Å, β = 134.040(2)◦,
V = 2243.9(5) Å3, Z = 4 for 1, and a = 8.1284(8) Å, b = 15.6112(15)
Å, c = 18.9260(17) Å, β = 106.060(3)◦, V = 2307.9(4) Å3, Z =
4 for 2. The Co atom in each complex is coordinated by one
Schiff base ligand, one 2-acetylphenolate ligand, and one pseu-
dohalide ligand (N3 for 1 and NCS for 2), forming an octahedral
geometry.
EXPERIMENTAL
Materials and Methods
All chemicals and solvents used for the syntheses were of an-
alytical grade. 1-(2-Hydroxyphenyl)ethanone and 2-piperidin-
1-ylethylamine were purchased from Aldrich Chemical Com-
pany, and other chemicals were obtained from commercial
sources and used without further purification. Elemental analy-
ses were performed on a Perkin-Elmer 240C analytical instru-
ment. The metal analysis was carried out by titration. IR spectra
in the 4,000-400 cm−1 range were measured with a Thermo
Nicolet 320 FT-IR spectrometer using KBr discs.
Keywords cobalt, crystal structure, Schiff base, synthesis
INTRODUCTION
Schiff bases are considered as a very important class of
organic compounds that have wide applications in coordina-
tion chemistry and biological aspects.[1–3] Mono- and multin-
uclear complexes of cobalt in its varied oxidation states have
become a central theme of current research because of their po-
tentially applications in many fields.[4–6] In the last few years,
cobalt complexes with multi-dentate Schiff base ligands have
been widely used to mimic cobalamine (B12) coenzymes.[7–9]
Among the N, O containing chelators, the tridentate mono-
condensed Schiff base ligands have received much attention for
the synthesis of mono- and polynuclear complexes. The copper,
nickel, zinc, and manganese complexes with tridentate mono-
condensed Schiff bases have widely been reported; however,
the cobalt complexes with such ligands have been reported on
relatively less. A literature search reveals that the Schiff base
Synthesis of the Schiff Base
2-[1-(2-piperidin-1-ylethylimino)ethyl]phenol (HL1)
To a vigorously stirred methanol solution (30 ml) of
1-(2-hydroxyphenyl)ethanone (0.136 g, 1 mmol), a methanol
solution (20 ml) of 2-piperidin-1-ylethylamine (0.128 g, 1
mmol) was added. The mixture was stirred for about 30 min and
then refluxed for 30 min. The resulting solution was evaporated
under vacuum to remove the solvent to give a yellow gummy
product. Anal. calc. for C15H22N2O: C, 73.13; H, 9.00; N,
11.37%. Found: C, 73.32; H, 9.08; N, 11.23%.
Synthesis of [Co(C15H21N2O)(C8H7O2)(N3)] (1)
To a methanol solution (10 ml) of cobalt nitrate hexahy-
drate (29.1 mg, 0.1 mmol), a methanol solution (10 ml) of HL1
(24.6 mg, 0.1 mmol) and 1-(2-hydroxyphenyl)ethanone (13.6
mg, 0.1 mmol) was added dropwise and the mixture was stirred
for 10 min. Then to the mixture was added a minimum volume of
aqueous solution of sodium azide (6.5 mg, 0.1 mmol) under stir-
Received 9 August 2010; accepted 6 October 2010.
The author acknowledges the Experimental Center of Linyi Normal
University for supporting this work.
Address correspondence to Li-Jun Liu, Experimental Center, Linyi
Normal University, Linyi Shandong 276005, P. R. China. E-mail:
xiaoerduoaa@hotmail.com
531

532
L.-J. LIU
TABLE 1
Crystallographic parameters of 1 and 2
ring. The resulting mixture was further stirred for 1 h at ambient
temperature to give a deep brown solution. The solution, on
slow evaporation, gave brown single crystals of the complex.
The crystals were filtered off and dried in air. Yield 27.3 mg
(57% based on Co). Anal. calc. for C23H28CoN5O3: C, 57.38;
H, 5.86; N, 14.55; Co, 12.24%. Found: C, 57.10; H, 5.97; N,
14.70; Co, 12.45%.
1
2
Empirical formula
Formula weight
Temperature (K)
Wavelength (Å)
Crystal system
Space group
Unit cell dimensions
a (Å)
C23H28CoN5O3
481.43
298(2)
0.71073
monoclinic
P21/c
C24H28CoN3O3S
497.48
298(2)
0.71073
monoclinic
P21/c
Synthesis of [Co(C15H21N2O)(C8H7O2)(NCS)] (2)
Complex 2 was obtained using the same procedure as de-
scribed for complex 1 taking sodium azide in place of ammo-
nium thiocyanate (7.6 mg, 0.1 mmol). The brown crystals of
2 were filtered off and dried in air. Yield 33.0 mg (66% based
on Co). Anal. calc. for C24H28CoN3O3S: C, 57.94; H, 5.67;
N, 8.45; Co, 11.85%. Found: C, 57.73; H, 5.75; N, 8.31; Co,
12.03%.
13.190(2)
12.842(2)
18.428(2)
134.040(2)
2243.9(5)
4
1.425
0.800
1008
8.1284(8)
15.6112(15)
18.9260(17)
106.060(3)
2307.9(4)
4
b (Å)
c (Å)
β (◦)
V (Å3)
Z
ρcalc (g cm−3
)
1.432
0.865
1040
µ (mm−1
F(000)
)
X-Ray Crystallography
Diffraction intensities for both complexes were collected
on a Bruker SMART 1000 CCD area diffractometer equipped
with graphite monochromated Mo Kα radiation with a radia-
tion wavelength of 0.71073 Å using the ω-scan technique at
298(2) K. Absorption corrections were performed using the
SADABS program.[10] The structures were solved by direct
method and refined by full-matrix least-squares against F2 us-
ing SHELXTL.[11] All non-hydrogen atoms were refined with
anisotropic displacement parameters. Hydrogen atom isotropic
displacement parameters were all treated as riding on the parent
atoms (1.2 or 1.5 Ueq for the carbon H atoms). All hydrogen
atoms were generated geometrically and were included in the
refinement in the riding model approximation. Selected crys-
tallographic data are summarized in Table 1. Coordinate bond
lengths and angles are listed in Table 2.
Crystal size (mm)
θ Range for data
collection (∞)
Max. and min.
transmission
Reflections collected
Unique (Rint)
Observed reflections [I > 3032
2σ(I)]
0.20 × 0.20 × 0.18 0.30 × 0.30 × 0.28
2.21–26.99
2.24–27.00
0.8564, 0.8694
0.7813, 0.7937
17886
4885
18570
5028
3665
Restraints
0
0
Parameters
291
1.021
291
1.021
Goodness-of-fit on F2
Final R indices [I > 2σ(I)] R1 = 0.0445, wR2 R1 = 0.0364, wR2
= 0.1033
R1 = 0.0885, wR2 R1 = 0.0610, wR2
= 0.1221 = 0.0982
0.343 and –0.298 0.430 and –0.266
= 0.0834
R indices (all data)
Largest diffraction peak
and hole (eÅ−3
)
RESULTS AND DISCUSSION
A 1:1 molar ratio of 1-(2-hydroxyphenyl)ethanone and 2-
piperidin-1-ylethylamine in methanol was reacted to prepare the
unsymmetrical tridentate Schiff base ligand. The Co atom read-
ily adopts octahedral coordination in the complexes. The reac-
tion of the tridentate Schiff bases (L) bearing NNO donors with
cobalt salts usually gives [CoL2] complexes,[12–15] which made
the pseudohalides difficult to coordinate to the Co atom. In the
present work, the bidentate 1-(2-hydroxyphenyl)ethanone was
used as a secondary ligand. A tridentate Schiff base ligand and
M are in the range 20–30 ꢀ−1 cm2 mol−1, indicating they are
non-electrolytes.[16] Microanalytical analyses of the complexes
are in agreement with the formulae proposed by the single crys-
tal X-ray determination.
Infrared Spectra
Comparison of the IR spectra of the complexes with that
a bidentate 1-(2-hydroxyphenyl)ethanone supplied five donors, of the free ligands gives information regarding bonding sites
which made the small ligands such as azide and thiocyanate of the ligands. The complexes display intense peaks at 1605
easily furnish the octahedral coordination of the Co atoms. and 1577 cm−1 due to the carbonyl (C O) and azomethine
The air-stable, moisture-insensitive complexes were obtained (C
N) stretching, respectively, which are shifted by about
as deep brown crystals, which are soluble in a range of common 20–30 cm−1 to lower frequencies compared to the free ligands.
organic solvents such as methanol, ethanol, dichloromethane, The shift of these bands towards lower frequencies compared
acetonitrile, dimethylformamide, and dimethylsulphoxide, but to those of the free ligands indicates the coordination of the
are insoluble in water. The molar conductance values of the carbonyl O and imine N atoms to the metal center. For the
complexes measured in methanol at the concentration of 10−3 complexes, the phenolic C O stretching is observed at about

SYNTHESIS AND STRUCTURES OF COBALT(III) COMPLEXES
533
TABLE 2
Selected bond distances (Å) and bond angles (◦) for 1 and 2
1
Co1-O1
Co1-O3
Co1-N2
1.863(2)
1.9113(19) Co1-N1
Co1-O2
1.927(2)
1.903(2)
1.941(3)
86.16(8)
89.04(9)
91.80(8)
91.04(10)
177.27(9)
88.12(9)
92.63(9)
2.046(2)
94.86(10)
177.77(9)
86.23(9)
91.36(10)
90.92(9)
176.67(9)
90.91(8)
87.11(10)
Co1-N3
O1-Co1-N1
N1-Co1-O3
N1-Co1-O2
O1-Co1-N3
O3-Co1-N3
O1-Co1-N2
O3-Co1-N2
N3-Co1-N2
2
O1-Co1-O3
O1-Co1-O2
O3-Co1-O2
N1-Co1-N3
O2-Co1-N3
N1-Co1-N2
O2-Co1-N2
Co1-O1
Co1-O3
Co1-N2
1.8654(16) Co1-O2
1.8583(16) Co1-N1
2.0537(19) Co1-N3
1.9058(16)
1.8927(18)
1.910(2)
O3-Co1-O1
O1-Co1-N1
O1-Co1-O2
O3-Co1-N3
N1-Co1-N3
O3-Co1-N2
N1-Co1-N2
N3-Co1-N2
88.51(8)
95.08(8)
86.71(7)
174.10(8)
90.36(9)
91.87(8)
88.12(8)
90.35(8)
O3-Co1-N1
84.26(8)
93.50(7)
177.09(8)
89.57(9)
91.96(8)
FIG. 1. Molecular structure of 1 drawn with 30% probability ellipsoids for
non-hydrogen atoms.
O3-Co1-O2
N1-Co1-O2
O1-Co1-N3
O2-Co1-N3
O1-Co1-N2
O2-Co1-N2
other, with the dihedral angles of 70.3(3)◦ for 1 and 84.5(3)◦
for 2, respectively. The phenolic hydroxyls are deprotonated
on complexation. The azide and thiocyanate groups are nearly
linear and show bent coordination modes with the Co atoms.
In 1, N3-N4-N5/Co1-N3-N4 = 175.0(3)/120.2(2)◦; In 2,
N3-C24-S1/Co1-N3-C24 = 179.0(2)/175.4(2)◦.
176.80(7)
90.10(7)
1250 cm−1. The presence of new bands in the spectra of
the complexes in the range 420–580 cm−1 can be attributed
to the Co-O and Co-N stretching vibrations. The intense
absorption band of the azide ligand in 1 is observed at 2022
cm−1, and that of the thiocyanate ligand in 2 is observed
at 2071 cm−1
.
Crystal Structures
The molecular structures of the complexes 1 and 2 are shown
in Figures 1 and 2, respectively. The Co atom in each complex is
hexacoordinated with a N3O3 coordination mode arising from
one Schiff base ligand, one 1-(2-hydroxyphenyl)ethanone, and
one pseudohalide (azide for 1 and thiocyanate for 2). The coor-
dination is best described as a slightly distorted octahedral, with
the three trans angles lying in the ranges 176.7(1)–177.8(1)◦
for 1 and 174.1(1)–177.1(1)◦ for 2. The cis angles around
the Co atoms are also close to the ideal values for octahedral
geometry, ranging from 86.2(1) to 94.9(1)◦ for 1, and from
84.3(1) to 95.1(1)◦ for 2. The corresponding bond distances in
both complexes are comparable to each other. The distances of
Co1-N2 in both complexes are longer than those of the Co1-N1,
and both comparable to the Co-N distances observed in other
cobalt(III) complexes with Schiff bases.[14,15] The two benzene
rings in each complex are approximately perpendicular to each
FIG. 2. Molecular structure of 2 drawn with 30% probability ellipsoids for
non-hydrogen atoms.

534
L.-J. LIU
CONCLUSION
of some cobalt(II) tetra-halogens-dimethyl salen complexes. Inorg. Chim.
Acta 2007, 360, 2139–2144.
Two new cobalt(III) complexes have been synthesized and
characterized by various physicochemical studies. Conductivity
measurements show that both complexes have non-electrolytic
nature. The crystallographic study shows that the Co coordi-
nation spheres are distorted octahedrally. To the best of the
author’s knowledge, this is the first report of the crystal struc-
tures of complexes with the Schiff base 2-[1-(2-piperidin-1-
ylethylimino)ethyl]phenol.
6. Zhang, J.; Pan, F.; Cheng, H.; Du, W. Synthesis, crystal structures, and an-
tibacterial activity of cobalt(III) complexes with bidentate Schiff base lig-
ands. Synth. React. Inorg. Met.-Org. Nano-Met. Chem. 2010, 40, 211–215.
7. Amirnasr, M.; Schenk, K.J.; Gorji, A.; Vafazadeh, R. Synthesis
and spectroscopic characterization of [CoIII(salophen)(amine)2]ClO4
(amine
=
morpholine, pyrrolidine, and piperidine) complexes.
The crystal structures of [CoIII(salophen)(morpholine)2]ClO4 and
[CoIII(salophen)(pyrrolidine)2]ClO4. Polyhedron 2001, 20, 695–
702.
8. Cini, R.; Moore, S.J.; Marzilli, L.G. Strong trans influence methoxymethyl
ligand in B12 cobaloxime and imine/oxime model complexes: Structural,
spectroscopic, and molecular mechanics investigations. Inorg. Chem. 1998,
37, 6890–6897.
9. Polson, S.M.; Cini, R.; Pifferi, C.; Marzilli, L.G. Synthesis and x-ray struc-
tures of elusive imine/oxime-type organocobalt B12 complexes. NMR study
suggesting steric strain within the axially ligated benzimidazole. Inorg.
Chem. 1997, 36, 314–322.
10. Sheldrick, G.M. Program SADABS: Area-Detector Absorption Correction;
University of Go¨ttingen: Germany, 1996.
11. Sheldrick, G.M. A short history of SHELX. Acta Crystallogr. 2008, A64,
112–122.
SUPPLEMENTARY MATERIALS
CCDC 787914 and 787915 contain the supplementary
crystallographic data for complexes 1 and 2, respec-
tively. These data can be obtained free of charge via
http://www.ccdc.cam.ac.uk/conts/retrieving.html, or from the
Cambridge Crystallographic Data Centre, 12 Union Road,
Cambridge CB2 1EZ, UK; fax: +44 1223 336 033 or email:
deposit@ccdc.cam.ac.uk.
12. Gupta, S.K.; Hitchcock, P.B.; Kushwah, Y.S.; Argal, G.S. Synthesis, struc-
ture and DNA binding studies of a mononuclear cobalt(III) complex with
a NNO donor Schiff base derived from 4-methyl-2,6-dibenzoylphenol
and ethane-1,2-diamine. Inorg. Chim. Acta 2007, 360, 2145–
2152.
13. Benson, T.H.; Bilton, M.S.; Gill, N.S.; Sterns, M. Isomers of bis[(R)-
N-(aminopropyl)salicylaldiminato]cobalt(III) and chromium(III) cations.
Circular dichroism and X-ray structure analysis. Chem. Commun. 1976,
936–937.
REFERENCES
1. Constable, E.C.; Zhang, G.; Housecroft, C.E.; Zampese, J.A. Mix and
match: Templating chiral Schiff base ligands to suit the needs of the metal
ion. Dalton Trans. 2010, 39, 5332–5340.
˙
2. So¨nmez, M.; C¸ elebi, M.; Berber, I. Synthesis, spectroscopic and biologi-
cal studies on the new symmetric Schiff base derived from 2,6-diformyl-
4-methylphenol with N-aminopyrimidine. Eur. J. Med. Chem. 2010, 45,
1935–1940.
14. Zhu, Q.-Y.; Wei, Y.-J.; Wang, F.-W. Anion-controlled synthesis, charac-
terization, and crystal structures of a pair of Schiff base cobalt com-
plexes. Synth. React. Inorg. Met.-Org. Nano-Met. Chem. 2007, 37, 557–
561.
3. Abdel-Aal, W.S.; Hassan, H.Y.; Aboul-Fadl, T.; Youssef, A.F. Phar-
macophoric model building for antitubercular activity of the individual
Schiff bases of small combinatorial library. Eur. J. Med. Chem. 2010, 45,
1098–1106.
15. Wei, Y.-J.; Wang, F.-W. Syntheses, characterization, and crystal structures
of two structurally similar Schiff base cobalt(III) complexes. Synth. React.
Inorg. Met.-Org. Nano-Met. Chem. 2006, 36, 723–727.
16. Geary, W.J. The use of conductivity measurements in organic solvents for
the characterisation of coordination compounds. Coord. Chem. Rev. 1971,
7, 81–122.
4. Saghatforoush, L.A.; Chalabian, F.; Aminkhani, A.; Karimnezhad, G.;
Ershad, S. Synthesis, spectroscopic characterization and antibacterial ac-
tivity of new cobalt(II) complexes of unsymmetrical tetradentate (OSN2)
Schiff base ligands. Eur. J. Med. Chem. 2009, 44, 4490–4495.
5. Pui, A.; Policar, C.; Mahy, J.P. Electronic and steric effects in cobalt
Schiff bases complexes: Synthesis, characterization and catalytic activity