Isolation of first row transition metal-carboxylate zwitterions

Article abstract of DOI:10.1039/c5ra05564d

Zwitterionic 3d metal carboxylates of Zn(ii), Cu(ii), Ni(ii) and Co(ii) have been isolated and structurally authenticated by X-ray crystallography. A series of 2-hydroxymethylpyridine-carboxylate ligands with different sizes and shapes demonstrate variabl

Full text of DOI:10.1039/c5ra05564d

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Lang, RSC Adv., 2015, DOI: 10.1039/C5RA05564D.
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DOI: 10.1039/C5RA05564D
ARTICLE
Isolation of first row transition metal–carboxylate
zwitterions†
Cite this: DOI: 10.1039/x0xx00000x
Mahsa Armaghan,abe W. Y. James Lu,a Di Wu,a Yao Wei,a Feng-Ling Yuan,c Seik
Weng Ng,f Mostafa M. Amini,e Wen-Hua Zhang,*ac David J. Young,*ad T. S.
Andy Hor*ab and Jian-Ping Langc
Received 00th January 2012,
Accepted 00th January 2012
Zwitterionic 3d metal carboxylates of Zn(II), Cu(II), Ni(II) and Co(II) have been isolated and
DOI: 10.1039/x0xx00000x
structurally authenticated by X-ray crystallography. A series of 2-hydroxymethylpyridine–
carboxylate ligands with different size and shape demonstrate variable coordination modes with
first row transition metals under different conditions, yielding a class of 17 complexes,
predominantly zwitterions. The nature of the ligands permits the carboxylates to be un-
coordinated, anionic and conjugated, thereby balancing the positive charges on the metal centers.
www.rsc.org/
these first row transition metal–carboxylate zwitterions and to
better understand the relationship between the structure of the
intermediates and the final MOFs, we have synthesized a series
Introduction
of
hydroxymethylpyridine–carboxylic
acids
or
Zwitterions, or inner salts, are neutral molecules with opposite
charges spatially separated in the same molecule.1 Naturally
occurring zwitterions are exemplified by the ubiquitous amino
hydroxymethylpyridine–carboxylate esters of different size and
shape (Chart 1) as ligands for Mn(II), Co(II), Ni(II), Cu(II) and
Zn(II) salts. We have been able to isolate an array of 17
molecular species, predominantly zwitterions. In doing so, we
have filled the literature gap in first row transition metal centered
zwitterions and have devised a general strategy for the synthesis
of zwitterionic coordination complexes.
+
– 2
acids, NH3 RCHCO2 . Synthetic metal–centered zwitterions,
with metal ions as the positive charge center have been reported
for the second and third row transition metals.3 The polarity and
solubility of these heavier metal centered zwitterions with borate,
carbanion, sulfonate, sulfate and phosphate-based ligands are
important for their roles in catalysis.3a The synthesis of first row
transition metal based zwitterions, particularly metal–
carboxylate zwitterions, is difficult because of the strong affinity
of carboxylate anions for hard metal cations.4 This hard acid–
base interaction has led to a plethora of discrete metal–
carboxylate clusters and, in the past 15 years, innumerable
metal–organic frameworks (MOFs) assembled from first row
transition metal ions and carboxylate-based organic ligands.5
Herein we report the synthesis of first row transition metal–
carboxylate zwitterions by employing functionalized 2-
hydroxymethylpyridine carboxylic acid or carboxylate ester
ligands.6
Examples
of
these
ligands,
ethyl
2-
(hydroxymethyl)isonicotinate
(
iso-ehmnH) and ethyl 6-
(hydroxymethyl)nicotinate (ehmnH) (Chart 1) were found to
react with Zn(NO3)2·6H2O to provide Zn–carboxylate
zwitterions
Zn(hmnH)2(H2O)2·2H2O
(hydroxymethyl)isonicotinate;
trans-Zn(iso-hmnH)2(H2O)2
(
1
)
and
=
=
cis-
2-
2-
(2
)
(
iso-hmnH
hmnH
(hydroxymethyl)nicotinate) which are intermediates in the
formation of MOFs.7 Complexes
and are polar species that
1
2
fluoresce blue and greenish-blue. To explore the diversity of
This journal is © The Royal Society of Chemistry 2013
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of iso-hmnH2 and hmnH2 with Co(NO3)2·6H2O or
Results and discussion
Ni(NO3)2·6H2O in DMF/H2O/MeCN in the presence of trace
amount of aqueous HNO3 provided diffraction qualVitieywcArryticsletaOlsnlionef
DOI: 10.1039/C5RA05564D
Reactions of Zn(NO3)2·6H2O with iso-ehmnH or ehmnH at
95 °C in DMF/H2O (1:1, v/v) yielded colorless and greenish-
orange solutions. Slow evaporation of these solutions at r.t. gave
rise to zwitterionic complexes trans-[Zn(iso-hmnH)2(H2O)2] (
and cis-[Zn(hmnH)2(H2O)2]·2H2O ( and are
zwitterions with the positive charges from Zn2+ remotely
neutralized by the two terminal carboxylates (Fig. 1). The
octahedral Zn center is completed by a pair of chelating pyridine
alcohol ligands and two coordinated water molecules. We
zwitterionic complexes trans-Co(iso-hmnH)2(H2O)2 (
Ni(iso-hmnH)2(H2O)2 ( ) and cis-[Ni(hmnH)2(H2O)2]·2H2O (
(Fig. S1, ESI
3
), trans
-
)
4
5
†
). Reaction of the corresponding metal chlorides,
1)
MCl2 (M = Co, Ni, Zn) yielded the same zwitterionic complexes
2
).7 Complex
1
2
as determined by single-crystal X-ray diffraction.
The strong Jahn-Teller effect for Cu(II) (d
9) makes the
reaction more susceptible to reaction variables such as ligand and
metal sources, counterions, solvents, temperatures etc. It was not
surprising, therefore, that we obtained different complexes (6–
11) from reactions involving Cu(II) and iso-hmnH2/hmnH2
under different reaction conditions (Scheme 1).
propose zwitterions
hydroxymethylpyridine is
1
and
a
2
are formed because
stronger chelator than the
carboxylate under these conditions and results in overall charge
neutrality. Notably, the isomeric ligands result in complexes of
opposite stereochemistry, viz trans in
study of the crystal packing of and
1
and cis in
2 (Fig. 1). The
1
2 also revealed extensive
hydrogen bonding interactions between coordinated water and
hydroxyl as donors and free carboxylates as acceptors (Fig. S4,
ESI†). These hydrogen bonding may also play a role in directing
the configuration of the ligands.
(a)
(a)
(b)
Fig.
[Cu(hmnH2)2(H2O)2][NO3]2 (
Symmetry codes for ( ): A –x, –y + 1, –z; and (
bond distances: C7–O2 1.213(5) Å, C7–O3 1.332(5) Å (
O3 1.203(3) Å ( ).
2
Structures of trans‐[Cu(iso‐hmnH2)2(NO3)2]∙2H2O
) (b) with the dissociated H2O molecules in
): A –x + 1, y +1, – z. Selected C–O
); C7–O2 1.324(4) Å, C7–
(
6
)
(a) and trans‐
7
6
omitted.
(b)
6
7
6
7
Fig.
[Zn(hmnH)2(H2O)2]∙2H2O (
Symmetry codes for ( ): A –x, –y + 1, –z; and (
distances: C7–O2 1.248(2) Å, C7–O3 1.249(2) Å (
1.264(2) Å ( ).
1
Structure of trans‐[Zn(iso‐hmnH)2(H2O)2]
) (b) with the dissociated H2O molecules in
): A –x, y, 0.5 – z. Selected C–O bond
); C7–O2 1.234(2) Å, C7–O3
(
1)
(a) and cis‐
2
2
omitted.
1
2
Reactions of Cu(NO3)2·3H2O with iso-hmnH2 or hmnH2 in
MeCN/MeOH at r.t. provided non-zwitterionic, octahedral
1
2
trans-[Cu(iso-hmnH2)2(NO3)2]·2H2O
(6
)
and
trans-
[Cu(hmnH2)2(H2O)2][NO3]2 (
7
) (Fig. 2). The ligands in both
cases invariably prefer
a
trans-arrangement, and could
Other metals salts MX2 (M = Co(II), Ni(II), Cu(II); X = NO3,
accommodate different secondary coordination groups (NO3
anion in and H2O in ).
When CuCl2·2H2O was used as the metal source, zwitterionic,
trigonal bipyramidal complexes [CuCl(iso-hmnH2)(iso
Cl) with iso-ehmnH and ehmnH resulted in amorphous, powdery
6
7
products under similar conditions as those for complexes
1 and
2
. We therefore hydrolyzed iso-ehmnH and ehmnH to their
-
respective acid forms iso-hmnH2 and hmnH2 (Chart 1). Reaction
2 | J. Name., 2012, 00, 1‐3
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hmnH)]·H2O (
which the 2+ charge on Cu is balanced by one Cl and one 2.648(6) Å,
carboxylate (Fig. 3a, 3c). The equatorial plane of the trigonal (Fig. 4a). The 2D network extends withinDtOhIe: 1b0c.10p3l9a/nCe5R(FA0ig5.5644bD)
bipyramid is formed by the terminal Cl and two cis O atoms from and stack of these sheets along the direction yields one
9
) and CuCl(hmnH2)(hmnH) (11) were isolated in uncoordinated O atoms in the neighboring carboxylate (O1···O3a
O1–H···O3a 179(7)
: –0.5 – , 0.5 + , 1.5 –

º
;
a
x
y
z)
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a
the pyridine alcohol ligands while the apical positions are dimensional channels wherein disordered DMF and H2O
occupied by two trans located N atoms. By contrast, the solvents reside (Fig. 4c). Powder X-ray diffraction confirmed the
reactions of CuCl2 with iso-hmnH2 in DMF/H2O or phase purity of
DMF/H2O/HNO3 under solvothermal conditions resulted in the indicated that the framework of
isolation of zwitterion trans-Cu(iso-hmnH)2(H2O)2 (10) which is after which decomposition follows accompanied by the loss of
structurally analogous to complex (Fig. 3b). DMF solvates (Fig. S3, ESI ).
8
(Fig. S2, ESI
†
). Thermogravimetric analysis
8
is stable till around 210 °C,
1
†
(a)
(b)
Scheme 1 Schematic presentation of the synthesis of complexes 6–11.
(c)
Fig. 3 Structures of [CuCl(iso‐hmnH2)(iso‐hmnH)]∙H2O (
hmnH)2(H2O)2] (10) (b) and [CuCl(hmnH2)(hmnH)] (11) (c) with the dissociated H2O
molecules in omitted. Selected C–O bond distances: C7–O2 1.264(3) Å, C7–O3
1.237(3) Å, C14–O5 1.321(3) Å, C14–O6 1.206(3) Å ( ); C7–O2 1.239(2) Å, C7–O3
9) (a), trans‐[Cu(iso‐
The reaction of hmnH2 with either Cu(NO3)2·3H2O or
CuCl2·2H2O under solvothermal conditions provided the same
9
9
1.260(2) Å (10); C7–O2 1.263(2) Å, C7–O3 1.241(2) Å, C14–O5 1.200(2) Å, C14–O6
1.315(2) Å (11).
2D,
non-zwitterionic
polymeric
) (Scheme 1). The Cu(II) center is
complex,
{[Cu(hmnH)2]·DMF·H2O}n (
8
octahedral with the equatorial plane containing a pair of
chelating N and O atoms from two trans-configuration hmnH
ligands. The axial positions are occupied by two monodentate
carboxylates. This results in an inter-connecting square-grid
structure that is further stabilized by strong hydrogen bonding
between the OH group of the pyridine alcohol moiety and the
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ehpbH (4,2,4-ehpbH = ethyl 4-(2-(hydroxymethyl)pyridin-4-
yl)benzoate; 3,2,4-mhpbH methyl 3-(2-
=
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(hydroxymethyl)pyridin-4-yl)benzoate; 4D,6O,3I:-1e0h.1p0b3H9/C=5ReAt0h5y5l644D-
(6-(hydroxymethyl)pyridin-3-yl)benzoate) (Chart 1). Reaction
of Zn(NO3)2·6H2O with 4,2,4-ehpbH, 3,2,4-mhpbH or 4,6,3-
ehpbH in DMF/H2O under solvothermal conditions gave rise to
zwitterions cis-Zn(4,2,4-hpbH)2(H2O)2
(12), trans-Zn(3,2,4-
hpbH)2(H2O)2 (13) and cis-[Zn(4,6,3-hpbH)2(H2O)2]·H2O (14
)
(4,2,4-hpbH
3,2,4-hpbH
4,6,3-hpbH
=
=
=
4-(2-(hydroxymethyl)pyridin-4-yl)benzoate;
3-(2-(hydroxymethyl)pyridin-4-yl)benzoate;
4-(6-(hydroxymethyl)pyridin-3-yl)benzoate)
(Scheme 2). Similar reaction of 3,2,4-mhpbH with
Co(NO3)2·6H2O and Ni(NO3)2·6H2O yielded trans-Co(3,2,4-
hpbH)2(H2O)2 (15) and trans-Ni(3,2,4-hpbH)2(H2O)2 (16) (Fig.
S1, ESI†) which are isostructural with zinc analogue 13
Reaction of 4,6,3-ehpbH with Mn(NO3)2·4H2O gave rise to a 2D
.
(a)
polymer [Mn(4,6,3-hpbH)2]n (17).
(b)
Scheme 2 Schematic presentation of the synthesis of cis‐Zn(4,2,4‐hpbH)2(H2O)2
(
12), trans‐Zn(3,2,4‐hpbH)2(H2O)2 (13) and cis‐[Zn(4,6,3‐hpbH)2(H2O)2]·H2O (14).
There are some notable differences in the structures of
complexes 12 16. The structures of 12 13 15 and 16 mirror
those of and (Scheme 2, Fig. 5a, 5b and Fig. S1, ESI ).
–
,
,
2
1
†
However, the stereochemistry of cis 14 in which the two pyridine
N atoms occupy equatorial and axial positions is in contrast to
homologue cis
2 in which both pyridine N atoms are trans
equatorial. Similarly, the cis stereochemistry of 12 and 14 is in
contrast to the trans stereochemistry of 13. The notable structural
diversity among these zwitterions presumably suggests the
varied
-donor ability and, therefore, trans influence of the
(c)
pyridine atom in their respective ligand.
Fig. 4 Structure of {[Cu(hmnH)2]∙DMF∙H2O}n (8) showing, (a) coordination
environment around Cu1, (b) 2D layer in bc plane and (c) stacking of the 2D layers
to generate 1D channels along the a axis. Symmetry codes: A –0.5 – x, 0.5 + y, 1.5
– z; B –x, 1 – y, 2 – z; C 0.5 + x, 0.5 – y, 0.5 + z.
We extended the spacers and conjugation in these ligands by
inserting a phenyl group between the ethyl carboxylate and
pyridinemethanol, viz. 4,2,4-ehpbH, 3,2,4-mhpbH and 4,6,3-
4 | J. Name., 2012, 00, 1‐3
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(a)
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DOI: 10.1039/C5RA05564D
(b)
(a)
(c)
Fig. 5 Structures of cis‐Zn(4,2,4‐hpbH)2(H2O)2 (12) (a), trans‐Zn(3,2,4‐hpbH)2(H2O)2
13) (b) and cis‐Zn(4,6,3‐hpbH)2(H2O)2∙H2O (14) (c) with the dissociated H2O
(
molecules in 14 omitted for clarity. Symmetry codes for (12): A – x, y, 0.5 – z; (13):
A – x, y, 0.5 – z; (14): A – x + 1, y, 0.5 – z. Selected C–O bond distances: C13–O2
1.251(5) Å, C13–O3 1.271(4) Å (12); C13–O2 1.239(2) Å, C13–O3 1.253(2) Å (13);
C13–O2 1.268(2) Å, C13– O3 1.239(2) Å (14).
(b)
Fig. 6 Crystal structure of [Mn(4,6,3‐hpbH)2]n (17) showing, (a) the coordination
environment around Mn1, and (b) the 2D layered structure in the ac plane.
Hydrogen atoms except those on O4 and O1 in (a) are omitted.
Although polymeric compound 17 has the same metal-to-
ligand ratio as that of compound
8, the coordination
environments around each metal center are distinctively different.
The pyridine alcohol pair chelating Mn in 17 resembles that
found in 14, where the N atoms are cis and O atoms trans. This
disposition imposes the remaining sites, occupied by a pair of
monodentate carboxylates, into a cis orientation (Fig. 6a). Each
Mn(II) center connects to four adjacent centers through a pair of
Conclusions
Hydroxymethylpyridine–carboxylate (ester) ligands exhibit rich
coordination chemistry by virtue of cooperative functionality
that reacts differently under a diverse conditions of metal cations,
pyridine alcohol chelators and
a pair of monodentate
solvents
and
temperatures,
predominantly
yielding
carboxylates to generate a two-dimensional layered structure in
the ac plane (Fig. 6b). The different ligand arrangement in 17
unprecedented zwitterions of first row transition metals. This
variable coordination behavior includes: I) both the
hydroxymethylpyridine and carboxylic acid remaining
relative to that of
8 also prevents hydrogen bonding between the
alcoholic OH group and the proximate C=O group from the
carboxylate on the same metal center. Instead, inter-layer
protonated (
intact but the carboxylic acid is deprotonated to yield a zwitterion
10 12 16); III) admixture of types I and II ( and 11); IV)
the hydroxymethylpyridine proton remains intact and the
carboxylic acid proton removed and bridges another metal center
(8 and 17) and V) both the hydroxymethylpyridine proton and
carboxylic acid protons are removed to form high dimensional
MOFs. The reasons behind these structural and stereochemical
6 and 7); II) hydroxymethylpyridine proton remains
hydrogen bonding (O1···O5a 2.564(3) Å,
165(3)º; O4···O3b 2.559(3) Å, O4–H4O···O3b 164(3)º;
3, – , – + 2; : – + 2, – + 1, – + 4) is evident and the close
stacking of adjacent layers block the apertures of the 2D layers,
making 17 non-porous (Fig. S5, ESI ).

O1–H1O···O5a
(1
–
5
,
,
–
9

a
: –
x +
y
z
b
x
y
z
†
outcomes may originate from the different -donor ability of the
ligand or/and the rich hydrogen bonding interactions between
coordinated water/alcoholic OH (donor) and free carboxylate
(acceptor), and is one of the subjects of our future study.
Zwitterion is a type of polar functionality, and including such
function within MOFs may result MOFs with increased uptake
capabilities towards gases such as CO2. We are working towards
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these goals using pyridine alcohol ligands presented herein and (w), 1383 (s), 1366 (s), 1294 (s), 1272 (s), 1253 (s), 1216 (s),
their derivatives.
1135 (s), 1110 (s), 1077 (s), 1027 (s), 878 (m), 859 (s), 812 (m),
785 (m), 761 (s), 722 (m), 694 (m), 667 (m), 643 V(miew),Ar5tic6le1O(nwlin)e,
DOI: 10.1039/C5RA05564D
476 (w), 457 (m), 422 (w), 407 (w) cm–1.
Experimental
Synthesis of 2-(hydroxymethyl)isonicotinic acid (iso-hmnH2)
iso-EhmnH (4.84 g, 26.7 mmol) was dissolved in THF/H2O (40
mL, v:v = 1:1). KOH (4.58 g, 81.6 mmol, 3 eq.) was added as
solid and the mixture stirred at 100 °C for 20 h and then cooled
to r.t. The mixture was further cooled in ice-water and then
HNO3 added to adjust the pH to 4–5. The solvent was removed
under vacuum. The organic part in the solid mixture was then
extracted twice with 400 mL of ethanol and the solvent removed.
All chemicals and solvents used were of A.R. grade and
purchased from commercial suppliers. They were used without
further purification unless otherwise specified. 1H NMR spectra
were recorded on a Bruker (400 MHz) NMR spectrometer using
CDCl3 or DMSO-d6 as solvent. MS (ESI) experiments were
performed on an LCQ ion-trap mass spectrometer. Infrared
spectra were obtained on a Perkin Elmer 2000 FT-IR
spectrometer using KBr pellet. Elemental analyses were
performed on a Perkin–Elmer PE 2400 CHNS elemental
analyzer. Thermogravimetric analysis (TGA) was performed on
a TA Instruments Q500 thermogravimetric analyzer at a heating
rate of 10 °C/min under a nitrogen gas flow in an Al2O3 pan.
Powder X-ray diffraction (PXRD) spectra were recorded with a
Bruker D8 GADDS (General Area Detector Diffraction System)
micro-diffractometer equipped with a VANTEC-2000 area
The powder contains inorganic material was added in hot iso
-
propanol and then filtered, evaporation of iso-propanol yielded
1
iso-hmnH2 as white powder. Yield 2.93 g, 72%. H NMR (400
MHz, DMSO-
(d,
= 4.8 Hz, 1H), 4.62 (s, 2H), 4.42 (broad, 9H) ppm. 13C {1H}
NMR (101 MHz, DMSO- 6): 167.6, 163.9, 150.1, 141.3, 121.8,
d6): δ 8.61 (d, J = 5.0 Hz, 1H), 7.91 (s, 1H), 7.65
J
d
δ
120.1, 64.9 ppm. MS (ESI, MeOH, 150 °C): 152.07 m/z: [M–H]–.
Anal. Calcd. (%) for C7H7NO3: C 54.90, H 4.61, N 9.15; found:
C 54.64, H 4.16, N 9.15. IR (KBr pellet): 3420 (s, br), 3048 (m,
sh), 2939 (w), 2870 (w), 2642 (w), 1959 (w), 1667 (s), 1630 (s),
1618 (s), 1584 (s), 1546 (s), 1450 (m), 1413 (m), 1384 (s), 1334
(m), 1281 (w), 1252 (w), 1215 (w), 1117 (w), 1102 (w), 1061 (s),
1045 (s), 1027 (m), 985 (w), 974 (w), 946 (w), 905 (w), 879 (m),
788 (s), 773 (s), 731 (m), 697 (m), 681 (m), 661 (m), 627 (m),
569 (m), 500 (m), 421 (m) cm–1.
detector with
Φ rotation method. The X-ray generated from a
sealed Cu tube was monochromated by a graphite crystal and
collimated by a 0.5 mm MONOCAP (λ Cu-Kα = 1.54178 Å).
The tube voltage and current were 40 kV and 40 mA,
respectively.
Synthesis of ethyl 2-(hydroxymethyl)isonicotinate
(iso-
ehmnH) and ethyl 2-(hydroxymethyl)nicotinate (ehmnH)
Synthesis of 2-(hydroxymethyl)nicotinic acid (hmnH2)
2-(Hydroxymethyl)nicotinic acid (hmnH2) was prepared using
the same method as iso-hmnH2. Yield: approximately 75 %. 1H
Ethyl 2-(hydroxymethyl)isonicotinate (iso-ehmnH) and ethyl 2-
(hydroxymethyl)nicotinate (ehmnH) were synthesized following
the published procedure.6a Yield 50% for iso-ehmnH over two
1
NMR (400 MHz, DMSO-
7.50 (d,
= 8.0 Hz, 1H), 5.38 (br, 4H), 4.61 (s, 2H) ppm. 13C {1H}
NMR (101 MHz, DMSO- 6): 167.4, 164.1, 149.5, 137.1, 129.3,
d6): δ 8.95 (s, 1H), 8.20–8.23 (m, 1H),
steps from pyridine-2,4-dicarboxylic acid. H NMR (400 MHz,
J
CDCl3):
Hz, 1H), 4.84 (s, 2H), 4.40 (q,
1.40 (t,
= 7.1 Hz, 3H) ppm. 13C {1H} NMR (101 MHz, CDCl3):
165.3, 161.8, 149.6, 138.9, 121.8, 120.3, 64.8, 62.2, 14.5 ppm.
δ
8.69 (d,
J
= 5.0 Hz, 1H), 7.86 (s, 1H), 7.77 (d,
J = 4.9
d
δ
J
= 7.1 Hz, 2H), 3.59 (br, 1H),
119.4, 64.2 ppm. MS (ESI, MeOH, 150 °C): 152.07 m/z: [M–H]–.
Anal. Calcd. (%) for C7H7NO3: C 54.90, H 4.61, N 9.15; found:
C 53.19, H 4.45, N 8.75. IR (KBr pellet): 3390 (s), 2914 (br),
2631 (w), 2524 (m), 2481 (m), 2450 (m), 2024 (w), 2001 (w),
1971 (w), 1935 (w), 1724 (s), 1641 (s), 1607 (s), 1542 (m), 1449
(s), 1396 (s), 1331 (m), 1315 (m), 1241 (m), 1134 (s), 1077 (s),
1026 (m), 1001 (m), 964 (w), 865 (s), 822 (s), 743 (s), 687 (m),
637 (s), 525 (m), 483 (m), 456 (m) cm–1.
J
δ
MS (ESI, CHCl3, 150 °C): 182.1 m/z : [M+H]+. Anal. Calcd. (%)
for C9H11NO3: C 59.66, H 6.12, N 7.73; found: C 59.84, H 5.45,
N 7.82. IR (KBr pellet): 3241 (br), 2988 (w), 2908 (w), 2830 (w),
1728 (s), 1607 (s), 1567 (s), 1479 (m), 1448 (m), 1398 (s), 1366
(m), 1299 (s), 1232 (m), 1204 (s), 1098 (s), 1063 (s), 1024 (s),
923 (w), 905 (w), 868 (m), 813 (w), 767 (s), 717 (m), 687 (s),
600 (w), 493 (w) cm–1.
Synthesis
yl)benzoate (4,2,4-ehpbH)
of
ethyl
4-(2-(hydroxymethyl)pyridin-4-
Yield 52% for ehmnH over two steps from pyridine-2,5-
dicarboxylic acid. H NMR (400 MHz, CDCl3): δ 8.85 (s, 1H),
1
Step 1. Methyl 4-chloro-2-pyridinecarboxylate (0.86 g, 5.0
mmol), 4-(methoxycarbonyl)phenylboronic acid (1.30 g, 7.2
mmol) and K3PO4 (10.6 g, 50 mmol) were mixed in toluene (80
mL), and de-aerated using N2. PdCl2(dppf) (0.29 g, 0.36 mmol)
was added, and the mixture stirred at 110 °C for 48h under N2
atmosphere. The solution was evaporated to dryness under
vacuum, extracted with CHCl3 and then dried over MgSO4.
Subsequent column purification with EA/hexane (1:1, v:v) gave
a white solid of methyl 4-(2-(methoxycarbonyl)pyridin-4-
yl)benzoate. Yield: 1.20 g, 88% based on methyl 4-chloro-2-
8.07 (d,
(s, 2H), 4.20 (q,
NMR (101 MHz, CDCl3):
120.3, 64.7, 61.8, 14.6 ppm. MS (ESI, CHCl3, 150 °C): 182.3
m/z: [M+H]+, 204.1 m/z: [M+Na]+. Anal. Calcd. for C9H11NO3:
C, 59.66; H, 6.12; N, 7.73%. found: C, 60.01; H, 6.35; N, 7.92%.
IR (KBr pellet): 3417 (sh), 3214 (s), 2986 (m), 2910 (m), 2840
(m), 2776 (w), 2704 (m), 2646 (w), 2574 (w), 2417 (w), 2262
(w), 2138 (w), 1992 (w), 1877 (w), 1860 (w), 1716 (s), 1659 (sh),
1626 (w), 1604 (s), 1575 (s), 1496 (w), 1476 (s), 1453 (s), 1399
J
= 8 Hz, 1H), 7.34 (d,
= 7 Hz, 2H), 1.21 (t,
165.5, 164.0, 150.3, 138.1, 125.6,
J
= 8 Hz, 1H), 5.26 (s, 1H), 4.65
J
J
= 7 Hz, 3H). 13C {1H}
δ
6 | J. Name., 2012, 00, 1‐3
This journal is © The Royal Society of Chemistry 2012

Page 7 of 15
Journal Name
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ARTICLE
pyridinecarboxylate. 1HNMR (400 MHz, CDCl3):
4.8 Hz, 1H), 8.41 (s, 1H), 8.37 (s, 1H), 8.15 (d, = 7.4 Hz, 1H), (w), 1747 (m), 1716 (s), 1600 (m), 1589 (w), 1549 (w), 1508 (w),
7.88 (d,
δ
8.82 (d,
J
=
66.66, H 4.28, N 5.11. IR (KBr pellet): 3410 (w), 3025 (w), 2958
J
J
= 7.5 Hz, 1H), 7.78 – 7.70 (m, 1H), 7.60 (m, 1H), 3.97 1468 (w), 1439 (s), 1406 (w), 1329 (s), 1303 (s), 1V2ie7w7A(rtsic)l,e 1O2nl4in3e
DOI: 10.1039/C5RA05564D
(s, 3H), 4.05 (s, 3H) ppm. 13C {1H} (101 MHz, CDCl3): δ 166.9, (s), 1185 (w), 1136 (w), 1109 (w), 1084 (w), 1059 (w), 1002 (w),
166.0, 150.8, 149.2, 149.0, 141.8, 131.5, 130.9, 127.5, 125.1, 977 (w), 914 (w), 897 (w), 878 (w), 857 (w), 835 (w), 785 (m),
123.5, 53.4, 52.7 ppm. MS (ESI, MeOH, 150 °C): 272.08 m/z
:
777 (w), 755 (s), 723 (m), 709 (w), 688 (w), 676 (w), 623 (w),
[M+H]+. Anal. Calcd. for C15H13NO4: C 66.41, H 4.83, N 5.16; 594 (w), 535 (w), 486 (w), 419 (w) cm–1.
found: C 66.44, H 4.31, N 5.15. IR (KBr pellet): 3417 (w), 3078 Step 2. Methyl 3-(2-(hydroxymethyl)pyridin-4-yl)benzoate was
(w), 3042 (w), 3001 (w), 2952 (w), 2851 (w), 1955 (w), 1824 (w), formed as a white solid in 80% yield. In situ transesterification
1
1729 (s), 1716 (s), 1600 (s), 1575 (w), 1543 (w), 1451 (m), 1441 was not observed. H NMR (400 MHz, CDCl3):
δ
8.60 (d,
J
J
=
=
(s), 1420 (w), 1397 (w), 1377 (w), 1321 (s), 1292 (s), 1251 (s), 4.9 Hz, 1H), 8.30 (s, 1H), 8.09 (d,
J
= 7.8 Hz, 1H), 7.81 (d,
1238 (m), 1195 (w), 1185 (w), 1133 (m), 1120 (s), 1105 (m), 7.7 Hz, 1H), 7.55 (m, 2H), 7.43 (d,
J
= 4.7 Hz, 1H), 4.84 (s, 2H),
166.9, 160.6,
788 (w), 767 (s), 721 (m), 708 (w), 700 (w), 656 (w), 583 (w), 149.6, 148.5, 138.8, 131.7, 130.5, 129.6, 128.6, 120.8, 118.8,
528 (w), 499 (w), 477 (w), 435 (w), 407 (w) cm–1. 64.9, 52.7 ppm. MS (ESI, MeOH, 150 °C): 244.07 m/z: [M+H]+.
1050 (m), 1016 (w), 997 (w), 914 (w), 874 (w), 847 (m), 830 (w), 3.95 (s, 3H) ppm. 13C NMR (101 MHz, CDCl3):
δ
Step 2. To a degassed EtOH (100 mL) solution containing methyl Anal. Calcd. (%) for C14H13NO3: C 69.12, H 5.39, N 5.76; found:
4-(2-(methoxycarbonyl)pyridin-4-yl)benzoate (1.20 g, 4.4 mmol) C 69.48, H 4.89, N 5.63. IR (KBr pellet): 3424 (w), 3146 (w),
and NaBH4 (0.11 g, 3.0 mmol) was slowly added CaCl2 (0.50 g, 3069 (w), 3039 (w), 2949 (w), 2919 (w), 2847 (w), 2637 (w),
4.42 mmol) at 0 °C with stirring. After the addition completed, 2054 (w), 1982 (w), 1933 (w), 1888 (w), 1835 (w), 1768 (w),
the mixture was stirred for 3 h at the same temperature. The 1725 (s), 1612 (m), 1599 (m), 1585 (w), 1551 (w), 1493 (w),
reaction was quenched by dropwise addition of concentrated 1478 (w), 1438 (w), 1402 (m), 1362 (w), 1321 (m), 1309 (m),
H2SO4. The resultant mixture was evaporated to dryness under 1293 (m), 1258 (s), 1215 (w), 1203 (m), 1173 (w), 1113 (s), 1088
vacuum, extracted with CHCl3, then dried over anhydrous (m), 1067 (w), 1034 (s), 1005 (m), 980 (w), 966 (w), 916 (w),
MgSO4. Removal of solvent followed by column purification 898 (w), 864 (m), 834 (w), 824 (m), 774 (w), 758 (s), 698 (m),
with EA/hexane (3:1,
v:v) gave a white solid of the 678 (w), 664 (w), 628 (m), 580 (w), 545 (w), 500 (w), 465 (w),
transesterfication product ethyl 4-(2-(hydroxymethyl)pyridin-4- 422 (w) cm–1.
yl)benzoate. Yield: 0.90 g, 79%. 1H NMR (400 MHz, CDCl3):
δ
8.64 (d,
8.4 Hz, 2H), 7.50 (s, 1H), 7.45 (d,
4.42 (q,
ppm. 13C NMR (101 MHz, CDCl3):
J
= 5.1 Hz, 1H), 8.16 (d,
J
J
= 8.4 Hz, 2H), 7.70 (d,
= 5.1 Hz, 1H), 4.85 (s, 2H), yl)benzoate (4,6,3-ehpbH)
J
=
Synthesis
of
ethyl
4-(6-(hydroxymethyl)pyridin-3-
J
= 7.1 Hz, 2H), 3.67 (s, 1H), 1.42 (t,
J
= 7.1 Hz, 3H) Ligand 4,6,3-ehpbH was synthesized following the same route
δ
166.5, 160.3, 149.6, 148.5, as described for 4,2,4-ehpbH.
142.7, 131.5, 130.7, 127.5, 121.0, 118.8, 64.8, 61.6, 14.7 ppm. Step 1. Methyl 4-(6-(methoxycarbonyl)pyridin-3-yl)benzoate
MS (ESI, MeOH, 150 °C): 258.15 m/z: [M+H]+. Anal. Calcd. for was formed as a white solid in 72% yield. 1H NMR (400 MHz,
C15H15NO3: C 70.02, H 5.88, N 5.44; found: C 70.23, H 5.55, N CDCl3):
5.28. IR (KBr pellet): 3428 (w), 3154 (w), 2983 (w), 2908 (w), (s, 1H), 8.16 (s, 1H), 8.06 (m, 1H), 7.71 (s, 1H), 7.68 (s, 1H),
2844 (w), 2822 (w), 1713 (s), 1665 (w), 1636 (w), 1603 (s), 1577 4.04 (s, 3H), 3.96 (s, 3H) ppm. 13C NMR (101 MHz, CDCl3):
(w), 1547 (w), 1480 (w), 1465 (w), 1444 (w), 1419 (w), 1398 (w), 166.9, 165.9, 148.7, 147.6, 141.4, 139.1, 135.8, 130.9, 127.8,
1364 (w), 1315 (w), 1290 (m), 1276 (s), 1183 (w), 1126 (m), 125.6, 53.4, 52.7 ppm. MS (ESI, MeOH, 150 °C): 271.99 m/z
δ 8.98 (d, J = 1.8 Hz, 1H), 8.23 (d, J = 8.1 Hz, 1H), 8.18
δ
:
1117 (m), 1105 (m), 1066 (m), 1048 (w), 1029 (w), 1018 (w), [M+H]+. Anal. Calcd. (%) for C15H13NO4: C 66.41, H 4.83, N
1104 (w), 981 (w), 880 (w), 867 (w), 849 (w), 831 (m), 771 (s), 5.16; found: C 66.49, H 4.97, N 5.15. IR (KBr pellet): 3418 (w),
742 (w), 733 (w), 702 (w), 659 (w), 612 (w), 586 (w), 521 (w), 2959 (w), 2919 (w), 2840 (w), 1720 (s), 1608 (w), 1589 (w),
495 (w), 443 (w), 435 (w), 428 (w) cm–1.
1578 (w), 1558 (w), 1476 (w), 1449 (w), 1430 (s), 1418 (w),
1364 (w), 1317 (s), 1288 (s), 1273 (s), 1240 (s), 1190 (m), 1130
Synthesis of methyl 3-(2-(hydroxymethyl)pyridin-4- (m), 1124 (m), 1104 (s), 1033 (w), 1018 (w), 1001 (w), 950 (m),
yl)benzoate (3,2,4-mhpbH) 875 (w), 851 (m), 828 (w), 799 (w), 767 (s), 701 (m), 683 (w),
Ligand 3,2,4-mhpbH was synthesized following the same route 644 (w), 628 (w), 522 (w), 521 (w), 486 (w), 411 (w) cm–1.
as described for 4,2,4-ehpbH. Step 2. Transesterfication product ethyl 4-(6-
Step 1. Methyl 3-(2-(methoxycarbonyl)pyridin-4-yl)benzoate (hydroxymethyl)pyridin-3-yl)benzoate was formed as a white
was formed as a white solid in 92% yield. 1H NMR (400 MHz, solid in 70% yield. 1H NMR (400 MHz, CDCl3): δ 8.81 (s, 1H),
CDCl3)
(s, 1H), 8.14 (d,
(d, = 3.3 Hz, 1H), 7.59 (t,
3H). 13C NMR (101 MHz, CDCl3):
δ
8.81 (d,
J
= 4.7 Hz, 1H), 8.41 (d,
= 7.8 Hz, 1H), 7.88 (d,
= 7.8 Hz, 1H), 4.04 (s, 3H), 3.96 (s,
166.8, 166.1, 150.8, 149.2, NMR (101 MHz, CDCl3): δ 166.6, 159.2, 147.5, 142.3, 135.7,
J
J
= 1.2 Hz, 1H), 8.36 8.16 (s, 1H), 8.14 (s, 1H), 7.92 (dd,
= 7.8 Hz, 1H), 7.73 1H), 7.64 (s, 1H), 7.37 (d, = 8.1 Hz, 1H), 4.83 (s, 2H), 4.41 (q,
= 7.1 Hz, 2H), 3.75 (s, 1H), 1.42 (t,
= 7.1 Hz, 3H) ppm. 13
J = 8.1, 2.1 Hz, 1H), 7.66 (s,
J
J
J
J
J
J
C
δ
149.1, 137.9, 131.7, 131.0, 129.8, 128.6, 125.0, 123.5, 53.4, 52.8 134.9, 130.7, 130.6, 127.4, 120.9, 64.6, 61.5, 14.7 ppm. MS (ESI,
ppm. MS (ESI, MeOH, 150 °C): 272.11 m/z: [M+H]+. Anal. MeOH, 150 °C): 258.16 m/z: [M+H]+. Anal. Calcd. for
Calcd. (%) for C15H13NO4: C 66.41, H 4.83, N 5.16; found: C C15H15NO3: C 70.02, H 5.88, N 5.44; found: C 69.70, H 5.16, N
This journal is © The Royal Society of Chemistry 2012
J. Name., 2012, 00, 1‐3 | 7

RSC Advances
Page 8 of 15
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ARTICLE
5.29. IR (KBr pellet): 3413 (w), 3184 (m), 3059 (w), 3029 (w), C14H16N2NiO8: C 42.15, H 4.04, N 7.02; found: C 42.45, H 3.88,
3007 (w), 2953 (w), 2896 (w), 2838 (w), 2708 (w), 2658 (w), N 7.03. IR (KBr pellet): 3303 (s), 3086 (sh), 3055 (sh), 2848 (w),
View Article Online
1717 (s), 1607 (m), 1576 (w), 1514 (w), 1481 (w), 1433 (m), 2507 (s, br), 1953 (w), 1794 (sh), 1599 (s), 1542 (s), 1456 (m),
DOI: 10.1039/C5RA05564D
1418 (w), 1377 (m), 1364 (m), 1319 (w), 1290 (s), 1276 (s), 1210 1421 (s), 1387 (s), 1342 (m), 1289 (m), 1258 (m), 1220 (w), 1126
(w), 1187 (m), 1103 (s), 1073 (s), 1023 (w), 1007 (s), 979 (w), (w), 1105 (w), 1066 (s), 1027 (w), 1007 (w), 897 (w), 866 (w),
965 (w), 874 (w), 840 (m), 770 (s), 701 (s), 652 (w), 630 (w), 779 (s), 719 (m), 701 (s), 602 (w), 547 (w), 506 (w), 429 (m) cm–
1
552 (w), 476 (w), 424 (w), 410 (w) cm–1.
.
Synthesis of trans-[Zn(iso-hmnH)2(H2O)2] (1)
Synthesis of cis-[Ni(hmnH)2(H2O)2]·2H2O (5)
Mixture of Zn(NO3)2·6H2O (30 mg, 0.1 mmol) and iso-ehmnH Complex
(36 mg, 0.2 mmol) were dissolved in DMF/H2O (6 mL, = 1:1) using the same reaction conditions described for the synthesis of
and the mixture heated at 95 °C for 72h to give a colorless . Yield: 28 mg, 64% based on Ni. Anal. Calcd. (%) for
solution which was filtered. Slow evaporation of the solution C14H20N2NiO10: C 39.47, H 4.50, N 6.58; found: C 39.47, H 4.82,
yielded colorless crystals of which were collected, washed with N 6.45, corresponding to – 0.5H2O. IR (KBr pellet): 3538 (s),
5 was synthesized from Ni(NO3)2·6H2O and hmnH2
v:v
3
1
5
H2O and drying under vacuum. Yield: 25 mg, 62% based on Zn. 3255 (s), 3077 (s), 3049 (s), 2919 (m), 2844 (w), 2510 (w), 2010
MS (ESI, MeOH and trace DMF/H2O, 150 °C): 369.7 m/z: [M- (w), 1903 (w), 1687 (w), 1620 (s), 1596 (s), 1558 (s), 1509 (w),
2H2O+H]+. Anal. Calcd. (%) for C14H16N2O8Zn: C 41.45, H 3.98, 1482 (w), 1456 (w), 1396 (m), 1367 (s), 1338 (s), 1280 (s), 1255
N 6.91; found: C 41.78, H 3.74, N 7.01. IR (KBr pellet): 3347 (w), 1156 (m), 1136 (m), 1036 (s), 1006 (w), 952 (w), 870 (w),
(m), 3054 (m), 2914 (m), 2841 (m), 2513 (m), 1956 (w), 1683 867 (w), 779 (m), 718 (w), 688 (w), 658 (w), 632 (w), 546 (w),
(s), 1602 (s), 1549 (s), 1454 (s), 1386 (s), 1289 (m), 1258 (m), 474 (w), 426 (w) cm–1.
1218 (m), 1125 (m), 1103 (m), 1074 (s), 1027 (m), 1008 (w), 898
(m), 867 (m), 779 (s), 717 (m), 699 (s), 554 (w), 499 (w), 427 (w) Synthesis of trans-[Cu(iso-hmnH2)2(NO3)2]·2H2O (6)
cm–1.
Cu(NO3)2·3H2O (48 mg, 0.20 mmol) and iso-hmnH2 (61 mg, 0.4
mmol) were dissolved in MeOH/MeCN (6 mL, = 2:1). The
mixture was briefly stirred at r.t. and the small amount of
v:v
Synthesis of cis-[Zn(hmnH)2(H2O)2]·2H2O (2)
Complex
using the same reaction conditions described for the synthesis of evaporate to give green crystals of
. Yield: 29 mg, 66 % based on Zn. MS (ESI, MeOH and trace on Cu. MS (ESI, MeOH, 150 °C): 278.0 m/z: [Cu(iso
2
was synthesized from Zn(NO3)2·6H2O and ehmnH precipitate was filtered off. The filtrate was allowed to slowly
6
. Yield: 42 mg, 40% based
1
-
DMF/H2O, 150 °C): 369.8 m/z: [M–2H2O+H]+. Anal. Calcd. (%) hmnH2)(NO3)]+, 368.0 m/z: [Cu(iso-hmnH2)2–H]+. Anal. Calcd.
for C14H20N2O10Zn·2H2O: C 41.45, H 3.98, N 6.91; found: C (%) for C14H18CuN4O14: C 31.73, H 3.42, N 10.57; found: C
41.33, H 4.05, N 6.89. IR (KBr pellet): 3403 (s), 3116 (s), 3077 37.07, H 3.91, N 8.97, roughly corresponding to trans-[Cu(iso
-
(s), 2934 (m), 2857 (w), 2703 (w), 2444 (m), 2222 (m), 2004 (w), hmnH2)2(NO3)2]·2H2O – 2H2O + 3MeOH (C 34.61, H 4.44, N
1892 (w), 1778 (m), 1713 (w), 1614 (s), 1589 (s), 1558 (s), 1490 9.50). IR (KBr pellet): 3434 (br, s), 2839 (w), 2782 (w), 2642
(s), 1446 (s), 1369 (s), 1340 (s), 1276 (s), 1259 (m), 1223 (m), (w), 2505 (w), 2422 (w), 1952 (w), 1731 (m), 1638 (s), 1615 (s),
1154 (s), 1128 (m), 1078 (s), 1038 (s), 1004 (w), 939 (s), 877 (s), 1561 (m), 1476 (w), 1384 (s), 1281 (m), 1258 (m), 1211 (w),
866 (s), 848 (w), 800 (s), 772 (s), 719 (w), 687 (s), 653 (s), 544 1181 (w), 1123 (w), 1097 (w), 1076 (w), 1036 (w), 988 (w), 902
(s), 496 (w), 477 (w), 444 (m), 421 (s) cm–1.
(w), 871 (w), 808 (w), 761 (m), 721 (m), 687 (m), 575 (w), 532
(w), 472 (w), 426 (w) cm–1.
Synthesis of trans-[Co(iso-hmnH)2(H2O)2] (3)
Co(NO3)2·6H2O (29 mg, 0.1 mmol) and iso-hmnH2 (30 mg, 0.2 Synthesis of trans-[Cu(hmnH2)2(H2O)2][NO3]2 (7)
mmol) were dissolved in DMF/H2O/MeCN (6 mL, = 1:1:1) Complex was synthesized from Cu(NO3)2·3H2O and hmnH2
and 5 drops (ca. 0.25 mL) of 68 % HNO3 added. The mixture using the same reaction conditions described for the synthesis of
was kept at 100 °C for 36 h to give a large amount of orange . Yield: 15% based on Cu. MS (ESI, MeOH, 150 °C): 368.01
v
:
v
:v
7
6
crystals which were collected and dried under vacuum. Yield: 34 m/z [Cu(hmnH2)2–H]+. Anal. Calcd. (%) for C14H18CuN4O14: C
mg, 85% based on Co. Anal. Calcd. (%) for C14H16CoN2O8: C 31.73, H 3.42, N 10.57; found: C 34.23, H 3.24, N 10.41,
42.12, H 4.04, N 7.02; found: C 42.23, H 4.02, N 6.82. IR (KBr corresponding to trans-[Cu(hmnH2)2(H2O)2][NO3]2 – 2H2O (C
pellet): 3296 (s), 3069 (sh), 3052 (sh), 2841 (w), 2498 (s, br), 34.05, H 2.86, N 11.35). IR (KBr pellet): 3424 (sh), 3182 (s),
1669 (sh), 1598 (s), 1564 (s), 1456 (m), 1420 (s), 1387 (s), 1342 3058 (s), 2932 (sh), 2579 (w), 2426 (w), 2008 (w), 1874 (w),
(m), 1289 (m), 1256 (m), 1218 (w), 1124 (w), 1103 (w), 1068 (s), 1763 (w), 1725 (s), 1714 (s), 1619 (s), 1558 (w), 1498 (m), 1435
1023 (w), 1009 (w), 910 (w), 896 (m), 867 (w), 778 (s), 718 (m), (sh), 1385 (s), 1280 (m), 1257 (m), 1226 (s), 1210 (s), 1129 (s),
699 (s), 545 (w), 503 (w), 428 (m) cm–1.
1046 (s), 1034 (s), 980 (m), 941 (w), 870 (m), 844 (w), 825 (m),
775 (s), 761 (s), 696 (sw), 643 (m), 535 (w), 499 (w), 429 (w)
cm–1.
Synthesis of trans-[Ni(iso-hmnH)2(H2O)2] (4)
Complex
hmnH2 using the same reaction conditions described for the Synthesis of {[Cu(hmnH)2]·DMF·H2O}n (8)
synthesis of . Yield: 78% based on Ni. Anal. Calcd. (%) for
4 was synthesized from Ni(NO3)2·6H2O and iso-
3
8 | J. Name., 2012, 00, 1‐3
This journal is © The Royal Society of Chemistry 2012

Page 9 of 15
Journal Name
RSC Advances
ARTICLE
Cu(NO3)2·3H2O (24 mg, 0.1 mmol) and hmnH2 (30 mg, 0.2 (s), 1499 (w), 1388 (s), 1375 (s), 1351 (w), 1331 (w), 1259 (s),
mmol) were dissolved in DMF/H2O/EtOH (6 mL, = 1:1:1) 1229 (s), 1211 (m), 1153 (w), 1136 (s), 1046 (s), 1031 (s), 996
v:v:v
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and 5 drops of 68% HNO3 added (ca. 0.25 mL). The mixture was (w), 983 (w), 945 (w), 884 (w), 872 (m),D8O6I:210(.m10)3,98/C052RA(s0)5,57647D8
kept at 100 °C for 36 h to give a light blue solution. Slow (s), 755 (m), 706 (w), 682 (w), 652 (w), 539 (m), 514 (w), 502
evaporation of the solution yielded light blue crystals of 8
, which (w), 471 (w), 425 (w) cm–1.
were collected and dried under vacuum. Yield: 15 mg, 33%
based on Cu. Anal. Calcd. (%) for C17H21CuN3O8: C 44.49, H Synthesis of cis-Zn(4,2,4-hpbH)2(H2O)2 (12)
4.61, N 9.16; found: C 44.60, H 3.57, N 8.32, corresponding to Zn(NO3)2·6H2O (11.2 mg, 0.038 mmol) and 4,2,4-ehpbH (19.3
[Cu(hmnH)2·0.5DMF·0.5H2O]n (C15.5H17CuN2.5O7: C 44.98, H mg, 0.075 mmol) were dissolved in DEF/EtOH/H2O (5 mL, v:v:v
4.14, N 8.46). IR (KBr pellet): 3469 (m), 3077 (m), 3048 (m), = 2:2:1) and transferred to a glass bottle with screw cap. The
2949 (w), 2907 (w), 2805 (w), 2661 (w), 2514 (w), 2431 (w), bottle was heated in a programmable oven smoothly from 25 ºC
1891 (w), 1714 (m), 1671 (s), 1618 (s), 1602 (s), 1557 (s), 1498 to 110 ºC within 4 h and at 110 ºC for 3 days, and then cooled to
(w), 1439 (w), 1391 (s), 1347 (s), 1282 (s), 1255 (w), 1235 (w), r.t.. The formed colorless crystals of 12 were collected by
1164 (m), 1135 (w), 1099 (w), 1063 (m), 1045 (s), 986 (w), 922 filtration, wash with DMF and dry under vacuum. Yield: 15 mg,
(w), 868 (m), 854 (m), 799 (m), 733 (s), 726 (w), 686 (w), 671 72% based on Zn. MS (ESI, MeOH and trace DEF, 150 °C):
(w), 657 (m), 573 (w), 520 (m), 475 (w), 434 (m) cm–1.
325.61 m/z: [Zn(4,2,4-hpbH)+MeOH]+. Anal. Calcd. (%) for
C26H24N2O8Zn: C 55.98, H 4.34, N 5.02; found: C 55.76, H 4.02,
N 4.94. IR (KBr pellet): 3285 (w), 2974 (w), 2923 (w), 2831 (w),
Synthesis of [CuCl (iso-hmnH2)(iso-hmnH)]·H2O (9)
CuCl2·2H2O (17 mg, 0.1 mmol) and iso-hmnH2 (30 mg, 0.2 2607 (w), 2567 (w), 1930 (w), 1676 (w), 1619 (s), 1601 (s), 1561
mmol) were dissolved in MeOH/MeCN (12 mL, = 2:1) and (s), 1542 (sh), 1509 (w), 1470 (w), 1410 (w), 1364 (s), 1334 (m),
the solution was slowly evaporated at r.t. to give blue crystals of 1282 (m), 1250 (w), 1193 (w), 1176 (w), 1134 (w), 1097 (w),
which were collected and dried under vacuum. Yield: 35 mg, 1087 (m), 1049 (m), 1017 (w), 965 (w), 885 (w), 868 (w), 838
v:v
9
82% based on Cu. Anal. Calcd. (%) for C14H15ClCuN2O7: C (m), 787 (s), 734 (w), 706 (w), 645 (w), 595 (w), 538 (w), 513
39.82, H 3.58, N 6.63; found: C 39.82, H 4.32, N 6.57. IR (KBr (w), 488 (w), 439 (w), 413 (w) cm–1.
pellet): 3520 (s), 3420 (s), 3095 (m), 3051 (m), 2971 (m), 2892
(m), 2779 (m), 2695 (m), 2632 (m), 2585 (m), 2541 (m), 1947 Synthesis of trans-Zn(3,2,4-hpbH)2(H2O)2 (13)
(w), 1921 (w), 1718 (m), 1621 (s), 1590 (s), 1568 (s), 1552 (s), Complex 13 was synthesized following the same route as
1491 (w), 1445 (m), 1382 (s), 1278 (s), 1248 (s), 1204 (s), 1116 described for 12. Yield 47% (based on Zn) as colorless crystals.
(w), 1100 (w), 1063 (s), 1035 (m), 909 (w), 893 (w), 863 (w), MS (ESI, MeOH and trace DEF, 150 °C): 325.56 m/z: [Zn(3,2,4-
784 (m), 765 (s), 714 (w), 700 (s), 683 (s), 652 (w), 590 (w), 539 hpbH)+MeOH]+. Anal. Calcd. (%) for C26H24N2O8Zn: C 55.98,
(w), 500 (w), 472 (m), 432 (m) cm–1.
H 4.34, N 5.02; found: C 55.41, H 4.23, N 4.99. IR (KBr pellet):
3266 (br), 3059 (w), 2931 (w), 2641 (w), 2503 (w), 1620 (s),
1591 (s), 1546 (vs), 1471 (w), 1447 (m), 1380 (vs), 1313 (w),
Synthesis of trans-Cu(iso-hmnH)2(H2O)2 (10)
CuCl2·2H2O (9 mg, 0.1 mmol) and iso-hmnH2 (15 mg, 0.2 mmol) 1274 (m), 1197 (w), 1167 (w), 1123 (w), 1077 (m), 1052 (s),
were dissolved in DMF/H2O (6 mL, = 1:1) and 5 drops of 68 % 1025 (m), 961 (w), 923 (w), 904 (w), 880 (w), 839 (m), 819 (w),
v:v
HNO3 (ca. 0.25 mL) added. The mixture was kept at 85 °C for 769 (s), 754 (m), 728 (w), 711 (w), 689 (w), 678 (s), 630 (m),
72h to give olive green crystals of 10 which was collected and 546 (w), 501 (m), 478 (w), 437 (w), 415 (w) cm–1.
dried under vacuum. Yield: 22 mg, 55% based on Cu. Anal.
Calcd. (%) for C14H16CuN2O8: C 41.64, H 3.99, N 6.94; found: Synthesis of cis-Zn(4,6,3-hpbH)2(H2O)2 (14)
C 41.10, H 3.65, N 7.00. IR (KBr pellet): 3385 (s), 3294 (s), 3130 Complex 14 was synthesized following the same route as
(s), 3088 (s), 3050 (s), 2905 (m), 2838 (m), 2721 (m), 1952 (w), described for 12. Yield 62% (based on Zn) as colorless crystals.
1618 (s), 1554 (s), 1494 (w), 1451 (m), 1384 (s), 1296 (m), 1278 MS (ESI, MeOH and trace DEF, 150 °C): 325.60 m/z: [Zn(4,6,3-
(m), 1259 (m), 1213 (w), 1125 (w), 1100 (w), 1076 (m), 1035 hpbH)+MeOH]+, 404.89 m/z: [Zn(4,6,3-hpbH)+NaCl+3H2O]+.
(w), 1006 (w), 972 (w), 911 (w), 898 (w), 866 (w), 790 (s), 782 Anal. Calcd. (%) for C26H26N2O9Zn: C 54.23, H 4.55, N 4.86;
(s), 699 (s), 661 (w), 581 (w), 544 (w), 503 (w), 487 (w), 434 (w) found: C 53.68, H 4.23, N 4.78. IR (KBr pellet): 3436 (br), 3103
cm–1.
(w), 3071 (w), 3037 (w), 2932 (w), 2906 (w), 2865 (w), 2725 (w),
2426 (w), 1950 (w), 1630 (w), 1609 (w), 1588 (m), 1566 (w),
1533 (m), 1489 (w), 1447 (w), 1415 (m), 1385 (s), 1369 (sh),
Synthesis of CuCl(hmnH2)(hmnH) (11)
CuCl2·2H2O (17 mg, 0.1 mmol) and hmnH2 (30 mg, 0.2 mmol) 1317 (w), 1301 (w), 1243 (w), 1215 (w), 1183 (w), 1138 (w),
were dissolved in MeOH/MeCN (12 mL, = 2:1) and the 1108 (w), 1062 (w), 1046 (m), 1025 (w), 1010 (w), 990 (w), 948
v:v
solution was slowly evaporated at r.t. to give blue crystals of 11 (w), 871 (w), 832 (w), 819 (w), 790 (s), 744 (w), 731 (w), 720
which were collected and dried under vacuum. Yield: 25 mg, 62% (w), 706 (w), 668 (w), 649 (w), 566 (w), 551 (w), 525 (w), 496
based on Cu. Anal. Calcd. (%) for C14H13ClN2O6Cu: C 41.59, H (w), 448 (w), 438 (w), 418 (w) cm–1.
3.24, N 6.93; found: C 40.73, H 3.15, N 6.78. IR (KBr pellet):
3185 (m), 3062 (m), 2921 (m), 2770 (m), 2607 (m), 2533 (m), Synthesis of trans-Co(3,2,4-hpbH)2(H2O)2 (15)
2500 (m), 2004 (w), 1886 (w), 1708 (s), 1616 (s), 1586 (s), 1557
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Co(NO3)2·6H2O (3.6 mg, 0.013 mmol) and 3,2,4-mhpbH (6.0 to r.t. during one and half days to provide colorless crystals of 17
.
mg, 0.025 mmol) were dissolved in DMF/EtOH/H2O (9 mL, Yield: 2 mg, 39.1% based on Mn. Anal. Calcd. (%) for
View Article Online
v:v:v = 4:4:1) and transferred to a 50 mL glass reactor with screw C26H20MnN2O6·H2O: C 58.99, H 4.19, ND5O.I2: 910;.1f0o3u9n/dC:5RCA05585.6445D,
cap. The bottle was transferred to a programmable oven and H 4.07, N 5.48. IR (KBr pellet): 3430 (br), 3057 (w), 2927 (w),
heated smoothly from 25 ºC to 110 ºC within 4 h and at 130 ºC 2887 (w), 2825 (w), 2821 (w), 2579 (br), 1606 (vs), 1593 (vs),
for 3 days before cooling to r.t. within 1.5 days to provide light 1570 (s), 1548 (s), 1519 (m), 1455 (s), 1388 (vs), 1308 (w), 1279
orange crystals of 15. Yield 6 mg, 51% (based on Co). Anal. (w), 1235 (w), 1224 (w), 1183 (w), 1141 (w), 1105 (w), 1066 (s),
Calcd. (%) for C26H24CoN2O8·0.5H2O: C 55.72, H 4.50, N 5.00; 1042 (m), 1009 (m), 969 (w), 941 (w), 930 (w), 872 (w), 833 (w),
found: C 55.40, H 4.32, N 5.00. IR (KBr pellet): 3234 (br), 3062 814 (w), 781 (s), 738 (w), 719 (w), 705 (m), 656 (m), 548 (m),
(s), 2925 (m), 2852 (m), 2641 (m), 2597 (m), 2509 (br), 1958 (w), 527 (m), 485 (w), 429 (w), 417 (w) cm–1.
1921 (w), 1619 (vs), 1591 (vs), 1565 (vs), 1545 (vs), 1474 (w),
1450 (m), 1398 (vs), 1378 (vs), 1312 (m), 1286 (m), 1273 (m), X-ray Crystallography
1200 (w), 1169 (w), 1122 (w), 1087 (w), 1073 (w), 1050 (vs),
Crystallographic measurements (except 12) were made on a
Bruker AXS APEX II diffractometer by using graphite-
monochromated Mo Kα (λ = 0.71073 Å) in the Institute of
Materials Research and Engineering. Complex 12 was measured
on an Agilent Technologies SuperNova Dual diffractometer with
Cu Kα (λ = 1.54178 Å) X-ray Source in University of Malaya.
The data were subjected for empirical absorption correction
1022 (m), 961 (w), 922 (w), 880 (m), 839 (m), 820 (m), 770 (vs),
754 (s), 732 (w), 690 (m), 679 (s), 629 (m), 592 (w), 549 (w),
502 (w), 484 (w), 437 (w), 418 (w) cm–1.
Synthesis of trans-Ni(3,2,4-hpbH)2(H2O)2 (16)
Complex 16 was synthesized following the same route as
described for 15 from Ni(NO3)2·6H2O and 3,2,4-mhpbH. Yield
41.6 % based on Ni. Anal. Calcd. (%) for C26H24N2NiO8·H2O: C
54.86, H 4.60, N 4.92; found: C 54.78, H 4.36, N 4.81. IR (KBr
pellet): 3275 (br), 3059 (w), 2924 (m), 2852 (w), 2503 (br), 1745
(w), 1621 (s), 1591 (m), 1565 (m), 1542 (vs), 1504 (w), 1476 (w),
1448 (m), 1440 (s), 1380 (vs), 1338 (w), 1313 (w), 1286 (w),
1274 (w), 1202 (w), 1167 (w), 1123 (w), 1087 (w), 1049 (s),
1026 (m), 963 (w), 921 (w), 901 (w), 880 (w), 840 (w), 820 (w),
770 (s), 755 (m), 730 (w), 689 (m), 679 (m), 631 (m), 549 (w),
503 (w), 481 (w), 459 (w), 439 (w) cm–1.
using SADABS8 (except 12
)
or spherical harmonics
implemented in SCALE3 ABSPACK scaling algorithm (12). All
crystal structures were solved by direct methods and refined on
F2 by full-matrix least-squares techniques with SHELXTL–97
program.9
For
8
, the DMF solvate adopts a symmetry induced disorder
1 instruction
and the symmetry was suppressed using PART
‒
with the occupancy factors further fixed at 0.50. For 14, the
dissociated water molecule is disordered by symmetry and
PART −1 was used to suppress the symmetry and the occupancy
factors were further fixed at 0.50. All the H atoms on the OH,
H2O and/or –COOH groups were found for the difference
Fourier map with O–H distances restrained to 0.83 Å while their
Synthesis of [Mn(4,6,3-hpbH)2]n (17)
Mn(NO3)2·4H2O (2.51 mg, 0.01 mmol) and 4,6,3-ehpbH (5.14
mg, 0.02 mmol) were dissolved in DMF/EtOH/H2O (4 mL, v:v:v
thermal parameter fixed to
the key crystallographic data for
U
iso(H) = 1.2
Ueq(O). A summary of
= 2:1:1). The solution was then placed in a 50 mL glass reactor
with screw cap in a programmable oven and heated smoothly
from r.t. to 110 ºC and kept at 110 ºC for 3 days before cooling
1
–
17 are listed in Table 1.
10 | J. Name., 2012, 00, 1‐3
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Table 1 Summary of Crystallographic Data for 1–17.
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View Article Online
Compounds
1
2
3
4
_________________________________________________________________________________________________________________
formula
FW
crystal system
space group
a (Å)
b (Å)
c (Å)
α (º)
C14H16N2O8Zn
405.66
Orthorhombic
Pbca
7.0534(4)
13.3638(8)
16.8646(10)
90.00
C14H20N2O10Zn
441.69
Monoclinic
C2/c
13.6211(6)
7.7315(4)
16.8791(8)
90.00
C14H16CoN2O8
399.22
Orthorhombic
Pbca
7.1867(3)
13.3223(6)
16.8797(7)
90.00
C14H16N2NiO8
399.00
Orthorhombic
Pbca
7.1353(4)
13.2866(8)
16.8095(10)
90.00
β (º)
γ (º)
V (Å3)
90.00
90.00
1589.66(16)
4
1.695
103.7790(10)
90.00
1726.41(14)
4
90.00
90.00
1616.12(12)
4
1.641
90.00
90.00
1593.61(16)
4
1.663
Z
ρ
calc (g cm–3)
1.699
F(000)
832
912
820
824
 (mm–1)
total reflns.
uniq. reflns.
obsd. reflns.
Rint
1.593
20767
1828
1528
0.0336
124
0.0233
0.0659
1.087
1.482
15177
2152
1944
0.0211
138
0.0234
0.0601
1.109
33694
4334
3448
0.0231
125
0.0358
0.1059
1.114
1.265
45407
5008
3552
0.0309
124
0.0323
0.0951
1.045
variables
a
R1
b
wR2
GOFc
1.085
0.376/–0.255
ρmax
ρ
min(e Å–3)
0.374/–0.301
0.588/–0.533
0.603/–0.496
/
_________________________________________________________________________________________________________________
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Table 1 Continued
View Article Online
______________________________________________________________________________________________D_O__I:_1_0_.1_0_3_9_/C_5_R_A_0_5_5_6_4_D
5
6
7
8
9
_________________________________________________________________________________________________________________
C14H20N2NiO10
435.03
Monoclinic
C2/c
C14H18CuN4O14
529.86
Monoclinic
P21/n
C14H18CuN4O14
529.86
Triclinic
P–1
C17H21CuN3O8
458.91
Monoclinic
P21/n
C14H15ClCuN2O7
422.27
Triclinic
P–1
13.3910(4)
7.7123(2)
16.9892(5)
90.00
104.4560(10)
90.00
8.5580(4)
10.3042(5)
12.2558(6)
90.00
108.0080(10)
90.00
7.256(6)
7.425(6)
9.897
89.716(17)
77.622(17)
86.150(19)
519.6(7)
1
7.451(2)
10.916(3)
12.454(4)
90.00
106.955(6)
90.00
7.7474(7)
9.0283(8)
11.6264(10)
81.603(2)
80.274(2)
81.512(2)
786.61(12)
2
1699.02(8)
4
1027.81(9)
2
968.9(5)
2
1.701
1.712
1.693
1.573
1.783
904
542
271
474
430
1.203
1.145
1.133
1.178
1.601
22722
14171
12033
15551
11032
3736
2456
2115
2231
2852
3266
2262
1954
1435
2564
0.0246
138
0.0182
163
0.0625
163
0.0983
163
0.0278
241
0.0277
0.0746
1.046
0.0527
0.1470
1.055
0.0350
0.0946
1.136
0.0719
0.2294
1.089
0.0279
0.0758
1.063
0.484/–0.269
2.473/–0.786
0.518/–0.759
1.705/–1.186
0.538/–0.514
_________________________________________________________________________________________________________________
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Table 1 Continued
View Article Online
______________________________________________________________________________________________D_O__I:_1_0_.1_0_3_9_/C_5_R_A_0_5_5_6_4_D
10
11
12
13
_________________________________________________________________________________________________________________
C14H16CuN2O8
403.83
Orthorhombic
Pbca
C14H13ClCuN2O6
404.25
Triclinic
P–1
C26H24N2O8Zn
557.84
Monoclinic
C2/c
C26H24N2O8Zn
557.84
Monoclinic
C2/c
6.9918(5)
13.1602(9)
17.1546(12)
90.00
90.00
90.00
7.5935(3)
7.7855(4)
14.6720(7)
83.0350(10)
86.3830(10)
61.4210(10)
756.08(6)
2
28.325(2)
7.1216(6)
12.6168(13)
90.00
114.533(14)
90.00
25.0244(9)
7.5228(3)
12.9729(5)
90.00
107.7859(7)
90.00
1578.45(19)
4
2315.3(4)
4
2325.47(15)
4
1.699
1.776
1.600
1.593
828
410
1152
1152
1.432
1.656
1.973
1.113
15498
33421
7792
10557
1805
4605
2402
2666
1501
4255
1991
2433
0.0296
124
0.0204
226
0.0929
180
0.0181
178
0.0247
0.0651
1.019
0.0242
0.0663
1.045
0.0572
0.1594
1.060
0.0289
0.0790
1.047
0.404/–0.336
0.449/–0.370
0.909/–0.959
0.483/–0.419
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Table 1 Continued
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______________________________________________________________________________________________D_O__I:_1_0_.1_0_3_9_/C_5_R_A_0_5_5_6_4_D
14 15 16 17
_________________________________________________________________________________________________________________
C26H26N2O9Zn
575.86
Monoclinic
C2/c
C26H24CoN2O8
551.40
Monoclinic
C2/c
C26H24N2NiO8
551.18
Monoclinic
C2/c
C26H20MnN2O6
511.38
Triclinic
P–1
26.264(2)
8.4871(8)
12.0334(11)
90.00
114.801(2)
90.00
25.051(11)
7.425(3)
12.951(6)
90.00
107.721(8)
90.00
24.917(4)
7.3870(11)
12.944(2)
90.00
107.482(4)
90.00
9.904(2)
10.165(2)
2.286(3)
77.470(3)
68.167(3)
85.302(3)
1120.9(4)
2
2434.9(4)
4
2294.8(16)
4
2272.6(6)
4
1.571
1.596
1.611
1.515
1192
1140
1144
526
1.069
0.806
0.912
0.636
7396
15227
11008
20302
2777
2637
2071
4246
2542
1495
1239
3197
0.0143
192
0.1697
178
0.1516
178
0.0544
322
0.0283
0.0857
1.043
0.0575
0.1167
0.988
0.0563
0.1290
1.009
0.0410
0.1069
1.017
0.414/–0.412
0.408/–0.437
0.482/–0.446
0.352/–0.377
_________________________________________________________________________________________________________________
2
2 2
2
a R1 = Σ||Fo|-|Fc||/Σ|Fo|. b wR2 = {Σ[w(Fo -Fc2)2]/Σ[w(Fo ) ]}1/2. c GOF = {Σ[w(Fo -Fc2)2]/(n-p)}1/2, where n is the number of reflections and p is
total number of parameters refined.
† Electronic Supplementary Information (ESI) available: CCDC numbers
Acknowledgements
984612, 984613 and 1013140–1013154. Crystal structures of
16, crystal packing diagram of 12 14 and 17, simulated and
TGA curves for See
3‒5, 15 and
This work was supported by IMRE assured funding 13-1C0203,
National Natural Science Foundation of China (No. 21401134),
Science and Technology Department of Jiangsu Province
(BK20140307) and Department of Education of Jiangsu
Province (14KJB150023). S.W.N. thanks the University of
Malaya (UM.C/625/1/HIR/247) for supporting this study.
1
,
2
,
‒
experimental PXRD patterns for
DOI: 10.1039/b000000x/
8
,
8.
1.
(a) R. Ramirez-Contreras, N. Bhuvanesh, J. Zhou and O. V. Ozerov,
Angew. Chem. Int. Ed., 2013, 52, 10313−10315; (b) J. Plešek, B.
Grüner, V. Šícha, V. Bőhmer and I. Císařová, Organometallics,
2012, 31, 1703−1715; (c) J. W. Dube, C. L. B. Macdonald and P. J.
Ragogna, Angew. Chem. Int. Ed., 2012, 51, 13026−13030; (d) T. T.
Ong, P. Kavuru, T. Nguyen, R. Cantwell, Ł. Wojtas and M. J.
Zaworotko, J. Am. Chem. Soc., 2011, 133, 9224−9227; (e) A. L.
Cresswell, M.-O. M. Piepenbrock and J. W. Steed, Chem. Commun.,
2010, 46, 2787−2789; (f) H. Li, A. J. A. Aquino, D. B. Cordes, F.
Hung-Low, W. L. Hase and C. Krempner, J. Am. Chem. Soc., 2013,
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Notes and references
a
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