Zinc(II) complexes with dangling functional organic groups

Article abstract of DOI:10.1002/ejic.201200558

Zinc(II) complexes with dangling functional organic groups were synthesized by reaction of zinc acetate with a series of bifunctional p-substituted benzene derivatives (a combination of carboxylate, oximate, amino, β-ketoimine, and salicylaldime groups).

Full text of DOI:10.1002/ejic.201200558

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FULL PAPER
DOI: 10.1002/ejic.201200558
Zinc(II) Complexes with Dangling Functional Organic Groups
Jingxia Yang,[a] Michael Puchberger,[a] Renzhe Qian,[b] Christian Maurer,[a] and
Ulrich Schubert*[a]
Keywords: Coordination polymers / Zinc / Carboxylate ligands / Schiff bases
Zinc(II) complexes with dangling functional organic groups
were synthesized by reaction of zinc acetate with a series of
ime or β-ketoimine group. When the second group was an
amine or salicylaldimine moiety, these groups were addition-
bifunctional p-substituted benzene derivatives (a combina- ally coordinated. From the reaction with p-aminobenzoic
tion of carboxylate, oximate, amino, β-ketoimine, and salicyl-
aldime groups). Selective coordination to carboxylate groups
was observed when the second functional group was an ox-
acid, the compound [Zn2(OOCCH3)(OOC–C6H4–NH2)3]ϱ was
crystallized. It is a three-dimensional coordination polymer
with bridging aminobenzoate ligands.
Introduction
Single-source precursors are mainly used in chemical
vapor deposition and sol–gel processing to introduce two
different elements into the final material. Typical single-
source precursors for sol–gel processing are bimetallic alk-
oxides in which the two metals are bridged by alkoxo
groups, which are then lost upon sol–gel processing (i.e.,
upon formation of mixed-oxide systems).[1] An unexploited
possibility is the option to utilize single-source precursors
to control the spatial arrangement of two components in
the final material. This requires a different composition of
the bimetallic precursor. Our approach is to link the indi-
vidual metal components through organic groups. Possible
synthesis routes of such precursors are shown in Scheme 1.
Silica-based mixed-metal oxides are mostly prepared by
route 1 because of the availability of a variety of alkoxy-
silanes (RO)3Si(CH2)3X, in which X is a coordinating group
(such as an amino[2] or β-diketonate group[3]). When (RO)3-
Si(CH2)3X is treated with metal ions or metal alkoxide moi-
eties (M), a bimetallic precursor [(RO)3Si(CH2)3X]nM is
formed. Sol–gel processing of such precursors was used to
prepare nanocomposite materials.[4] A recent example of
route 3 (the coupling of two ligands through appropriate
organic groups) is the coupling of 3-isocyanatopropyltri-
ethoxysilane with metal hydroxyacetates.[5]
Scheme 1. Synthesis routes for bimetallic precursors with organic
linkers.
A generalization of this method for the preparation of
mixed oxides of any two metallic elements is less straight-
forward. Routes 1 and 2 require bifunctional organic com-
pounds XЈ–Y–X with two different coordinating groups (X
and XЈ, Y = inert spacer). The challenge is that the func-
tional groups must selectively react with just one metal
component [i.e., coordination of either metal to both coor-
dination groups (which would lead to coordination poly-
mers) must be avoided].
We have previously given an example for route 1 by coor-
dinating lysine to titanium and zirconium alkoxides (chelate
formation by the carbonyl oxygen atom and the α-amino
group) followed by the coordination of metal ions to the
dangling ω-amino group.[6] The use of lysine cannot be gen-
eralized, however, because substitution of the metal alk-
oxides competes with lactam formation.[7]
[a] Institute of Materials Chemistry, Vienna University of
Technology,
1060 Wien, Austria
E-mail: uschuber@mail.zserv.tuwien.ac.at
Homepage: http://www.imc.tuwien.ac.at/
[b] Institute of Organic Chemistry, University of Vienna,
1090 Vienna, Austria
In this paper, we investigate the selectivity issue for Zn2+
ions (for proof of principle) by using various bifunctional
p-substituted benzene derivatives and report the synthesis
of complexes Zn(XЈ–Y–X)2. In a follow-up paper, we will
report on the following steps, specifically the coordination
Supporting information for this article is available on the
WWW under http://dx.doi.org/10.1002/ejic.201200558.
Re-use of this article is permitted in accordance with the Terms
and Conditions set out at http://onlinelibrary.wiley.com/journal/
10.1002/(ISSN)1099-0682c/homepage/2005_onlineopen.html
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J. Yang, M. Puchberger, R. Qian, C. Maurer, U. Schubert
FULL PAPER
of Ti(OR)4 to the dangling group X according to route 2, absence of signals for acetate groups in the NMR spectra
and sol–gel processing of the single-source precursor.[8] indicated that acetic acid, formed by the substitution reac-
Benzene derivatives were chosen to avoid backbiting of the tion, was removed during the workup procedure.
ligand, and the dangling groups X according to their ability
FTIR measurements confirmed these results. In the spec-
to coordinate to metal alkoxide moieties.[9] The complex trum of POBC-H (Figure 1, a), the bands at 1685, 1611,
Zn(PSBO)2 (PSBO-H = salicyliden-p-aminoacetophenone 1290, and 988 cm–1 correspond to νC=O, νC=N, νC–O, and
oxime), which has a dangling oxime functionality, was pre- νN–O, respectively. After coordination to Zn2+ (Figure 1, b),
viously reported[10] but is included here for comparison. the νC=O band was shifted from 1685 to 1549 cm–1 and that
Complexes MЈ–XЈ–Y–X are not only suitable building of νC–O from 1290 to 1410 cm–1. In contrast, the bands of
blocks for the preparation of mixed oxides by following νC=N and νN–O shifted only slightly, from 1611 to 1602 cm–1
route 2, but might also be useful as a new type of metal– for νC=N and from 988 to 979 cm–1 for νN–O
.
organic linker for metal–organic framework (MOF) struc-
tures.
The structures of zinc complexes are well documented
(see the literature[11] for classification and analysis of struc-
tural data). Therefore, this article does not deal with new
structures, but instead concentrates on testing the possibil-
ity of selective coordination of bifunctional ligands.
Results and Discussion
Given the high tendency of Zn2+ to form carboxylate
complexes, four benzoic acid derivatives with a second func-
tional group capable of coordinating to alkoxide moieties
in the para position were initially chosen, namely, p-carb-
oxybenzaldehyde oxime (POBC-H), p-[(3-hydroxy-1-meth-
yl-2-butenylidene)amino]benzoic acid (PSBCA-H), p-salic-
ylidene-p-aminobenzoic acid (PSBC-H), and p-amino-
benzoic acid (PABC-H) (Scheme 2).
Figure 1. FTIR spectra of POBC-H and Zn(POBC)2.
Similar results were obtained for PSBCA-H. The appear-
ance of two OH signals in the 1H NMR spectrum con-
firmed that the enol–imine form is the predominant tauto-
mer in the liquid phase (Figure S3 in the Supporting Infor-
mation), as previously reported.[12] In the crystalline state,
the keto–enamine tautomer was found.[12] An HMBC spec-
trum (Figure S4 in the Supporting Information) showed
that the resonance at δ = 12.81 ppm can be assigned to
COOH and the resonance at δ = 12.61 ppm to the enol OH
Scheme 2. Benzoic acid derivatives used as ligands.
1
The H NMR spectrum of POBC-H showed two signals group. After reaction with half a molar equivalent of zinc
in the region of acidic protons (Figure S1 in the Supporting acetate, the resonance of the COOH proton had disap-
Information). The heteronuclear multiple-bond correlation peared, whereas the other resonance was not significantly
(HMBC) spectrum allowed us to assign the peak at δ = shifted. In the 13C NMR spectra, the COO resonance was
12.99 ppm to COOH and the peak at δ = 11.52 ppm to shifted from δ = 166.72 to 170.87 ppm, whereas that of
NOH (Figure S2 in the Supporting Information). After re- C=C(Me)OH was slightly shifted from δ = 142.69 to
action of zinc acetate with two molar equivalents of POBC- 140.95 ppm. The other signals were almost unchanged.
H, the signal for COOH had disappeared, and the aromatic
PSBCA-H and the derived Zn complex were also charac-
protons ortho to the COO group had shifted from δ = 7.71 terized by FTIR (Figure S5 in the Supporting Information).
to 7.63 ppm. Furthermore, the COO signal in the 13C NMR The absorption bands of PSBCA-H for νCOO, νC=N, νC–O
,
spectrum was shifted from δ = 166.9 to 171.1 ppm (Fig- and νC–N are at 1695, 1595, 1286, and 1025 cm–1, respec-
ure S1 in the Supporting Information). The NMR spectro- tively. After reaction with Zn2+, νCOO shifted to 1579 cm–1
scopic data thus indicated coordination of the COO group and νC–O to 1314 cm–1. The bands for νC=N and νC–N were
1
to Zn2+. The signal of the NOH group in the H NMR unchanged at 1598 and 1026 cm–1. The NMR and FTIR
spectrum was also slightly shifted, from δ = 11.52 to spectra indicated that Zn2+ was coordinated to the carb-
11.37 ppm, but the C=N signal in the 13C NMR spectrum oxylate group and that the Schiff base moiety was un-
was not, which means the NOH was not coordinated. The changed.
2
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Zinc(II) Complexes with Dangling Functional Organic Groups
Based on the NMR and IR spectroscopic results, the 1317 to 1405 cm–1. The bands for C=N and CPh–O ap-
structures shown in Scheme 3 are proposed for Zn- peared at the same wavenumber as that of PSBC-H, but
(POBC)2 and Zn(PSBCA)2, in which the COO groups are with decreased intensity. Elemental analysis of the resulting
coordinated to Zn and the Y groups are dangling. This solid showed that the carbon content was slightly higher
composition was also supported by elemental analyses and than calculated for Zn(PSBC)2. Together with the spectro-
TGA measurements (by which the ZnO proportion is deter- scopic results this might indicate that the solid could be a
mined after burning off all organic components) (Fig- mixture of compounds with different coordination of the
ures S6 and S7 in the Supporting Information).
zinc ions. The important information in the context of this
work, however, is that there is no coordination selectivity
between the carboxylate and salicylaldimine group.
Zn(PABC)2 was previously prepared from a 1:2 ratio of
Zn(NO3)2·6H2O and PABC-H.[13] Its structure is a three-
dimensional coordination polymer with PABC as a bridg-
ing ligand. Each zinc atom is coordinated by two NH2
groups and three oxygen atoms (one of a bridging and two
of a chelating carboxylate group). Formation of a 3D net-
work structure was also observed when Zn(NO3)2·6H2O
was treated with 4-tetrazolyl benzene carboxylate.[14]
The spectra obtained by treating Zn(OAc)2 with PABC-
Scheme 3. Suggested structure of Zn(POBC)2 and Zn(PSBCA)2.
Somewhat different results were obtained for PSBC-H, a H in a 1:2 molar ratio were not very meaningful. When
carboxylate-substituted salicylaldimine. According to 1H a 1:4 ratio was employed, however, colorless crystals were
1
and 13C NMR spectroscopic data (Figures S8 and S9 in the obtained after 4 weeks. The COOH signal in the H NMR
Supporting Information), the coordination situation of spectrum disappeared and that of NH2 shifted from δ =
PSBC is more complex. When the employed Zn(OAc)2/ 5.87 to 5.51 ppm. This indicated that both NH2 and COO
PSBC ratio was 1:2 as before, the NMR spectra showed were coordinated to Zn2+. A single-crystal X-ray structure
that the COOH signal at δ = 12.97 ppm had disappeared analysis showed that a three-dimensional coordination
after the reaction, thus indicating that the carboxylate polymer with the composition [Zn2(OAc)(OOC–C6H4–
group was coordinated to Zn2+. This was confirmed by 13
NMR spectroscopy, in which the COO signal shifted from
C
NH2)3]ϱ was formed (Figure 2).
In the crystal structure of Zn2(OAc)(PABC)3, each PABC
δ = 166.82 to 170.98 ppm. Although there was only one molecule is coordinated to one zinc atom through the
signal for the COO group in the 13C NMR spectrum of amino group and to two other zinc atoms through the
the obtained Zn–PSBC complex, there were two signals for bridging carboxylate group. The acetate ligands are bridg-
salicylaldimine moieties. The first half of the groups were ing–chelating (i.e., the carboxylate group chelates one zinc
not coordinated. The 1H NMR spectroscopic signal for the atom, whereas one of the cyrboxylate oxygen atoms bridges
OH group shifted from δ = 12.71 to 12.89 ppm, and inte- two zinc atoms). There are two kinds of differently hexaco-
gration of the both the OH and N=CH signal (at δ = ordinated zinc atoms. One is coordinated by the oxygen
9.0 ppm) was reduced to 50%. The 13C NMR spectroscopic atoms of three bridging PABC ligands [in a mer arrange-
signal of the C–OH carbon was not shifted. The second half ment, O–Zn–O 96.0(1)–100.6(1)°], two amino groups, and
of the salicylaldimine moieties was coordinated to Zn2+. A one oxygen of an acetate ligand. The other type of zinc
second N=CH signal was observed at δ = 8.71 ppm with atoms is also coordinated by the oxygen atoms of three
50% intensity. Furthermore, part of the CH=N signal was bridging PABC ligands [in a mer arrangement, O–Zn–O
shifted from δ = 164.20 to 168.88 ppm.
111.4(2)–118.8(1)°] in addition to one amino group and the
When the experiment was repeated with a Zn(OAc)2/ chelating acetate ligand.
1
PSBC-H ratio of 1:3, the chemical shifts in the H NMR
The results with the functional carboxylic acids POBC-
spectrum were almost the same as for the 1:2 reaction. H, PSBCA-H, PSBC-H, and PABC-H showed a clear pref-
When both compounds were treated in a 1:1 ratio, the sig- erence for the coordination of the carboxylate group to
nal for OH was also present in the 1H NMR spectrum, Zn2+, a weaker tendency to coordinate salicylaldimine or
but with a decreased intensity. This indicated that both the amino groups, and no coordination of oximate or β-keto-
COOH and salicylaldimine group of PSBC can coordinate, iminate groups. This order of coordination ability was
but that coordination of COO was preferred.
cross-checked for a series of substituted methylphenyl
IR spectra confirmed the NMR spectroscopic results. ketoximes. Oximate groups are especially suitable for the
The spectrum of PSBC-H shows the stretching vibrations coordination of metal alkoxide moieties.[15]
of C=O, C=N, COO, and CPh–O at 1677, 1621, 1317, and
No differences were observed in the NMR spectra of PA-
1283 cm–1, respectively. After reaction of PSBC-H with BOM-H or PSBOA-H (Scheme 4) solutions before and af-
Zn(OAc)2, the IR spectra were almost the same for the ter the addition of zinc acetate. This indicates that no coor-
three samples prepared with different Zn/PSBC-H ratios dination occurred. Apparently, Ph–NH2 groups can only
(Figure S10 in the Supporting Information). The C=O coordinate to Zn2+ in a supportive manner, as observed for
band shifted from 1677 to 1590 cm–1 and that of COO from Zn2(OAc)(PABC)3 or Zn2(PABC)2.
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Figure 2. (a) Crystal structure of [Zn2(OAc)(OOC–C6H4–NH2)3]ϱ. (b) Section from the coordination polymer with four zinc atoms (two
Zn atoms are pairwise located behind one another) showing the arrangement of the PABC ligands. The acetate ligands are perpendicular
to the plane of the drawing (linear arrangement with the Zn–Zn axis).
ions and because the assignment of the NMR spectroscopic
signals is slightly different to what has been reported.
When PSBO-H was treated with Zn(OAc)2, the reso-
nance for C–OH at δ = 13.03 ppm disappeared and that of
N=CH shifted from δ = 8.98 to 8.80 ppm, whereas the sig-
nal of N–OH at δ = 11.26 ppm was nearly unchanged (Fig-
ures S11 and S12 in the Supporting Information). In the
13C NMR spectra, the imine C=N signal shifted from δ =
163.4 to 170.8 ppm and that of C–O from δ = 160.3 to
170.1 ppm. In the FTIR spectra (see Figure S13 in the Sup-
Scheme 4. Other benzene derivatives used for reaction with
Zn(OAc)2.
porting Information) the stretching vibrations of C=Nimine
,
C=Noxime, C–O, and N–O were observed at 1615, 1592,
1271, and 1002 cm–1 for PSBO-H. In the Zn–PSBO com-
plex, these bands were at 1604, 1589, 1293, and 1006 cm–1.
The complex Zn(PSBO)2 was already described by Can-
polat et al. (Scheme 5).[10] The spectroscopic data are in-
cluded here to illustrate the coordination selectivity of Zn2+
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Zinc(II) Complexes with Dangling Functional Organic Groups
Measurements: 1H and 13C solution NMR spectra were recorded
with a Bruker AVANCE 300 DPX (300.13 MHz for 1H, 75.47 MHz
for 13C) equipped with a 5 mm broadband-inverse probe head and
a z gradient unit. Infrared spectra were recorded with a Bruker
Tensor 27 working in ATR Micro Focusing MVP-QL with a ZnSe
crystal, and by using OPUS software version 4.0 for analysis. Ther-
mogravimetric analyses (TGA) were performed with a Netzsch Iris
TG 209 C instrument in a platinum crucible under synthetic air
with a heating rate of 10 °Cmin–1 from 40 to 900 °C. The theoreti-
cal values for the elemental analyses were calculated for the water-
free complexes; minor deviations of the found values therefore may
be due to small proportions (less than one equivalent) of water.
Scheme 5. Suggested structure of Zn(PSBO)2.
All spectroscopic data, as well as elemental analysis and
TGA data (Figure S14 in the Supporting Information), sup-
port the exclusive coordination of the salicylaldimine group
and formation of the complex Zn(PSBO)2 (Scheme 5).
p-Carboxybenzaldehyde Oxime (POBC-H): p-Carboxybenzalde-
hyde (4.5 g, 30 mmol) and NH2OH·HCl (3.13 g, 45 mmol) was dis-
solved in ethanol (90 mL) and then mixed with NaOAc (3.7 g,
45 mmol) in water (270 mL). The solution was heated at reflux for
5 h. The solution was then extracted three times by ethyl acetate
(EtOH/ethyl acetate ratio 1:4), once with brine, and dried with
Na2SO4. Evaporating the solvent from the mixture of EtOH and
ethyl acetate under reduced pressure resulted in 4.31 g of the E
Conclusion
1
isomer of POBC-H (yield: 87%). H NMR ([D6]DMSO): δ = 7.71
Reaction of various bifunctional p-substituted benzene
derivatives with zinc acetate showed that selective coordina-
tion of one of the functional groups is possible, whereas the
second, noncoordinated functional group is still available
for the coordination of another metal moiety. Among the
investigated functional groups, the preference for coordina-
tion to Zn2+ is –COOH Ͼ salicylaldimine Ͼ –NH2 ϾϾ
oxime, β-ketoimine. We found no indication for an interac-
tion of the latter two functional groups with Zn2+. During
the reaction, the acetate ligands of the employed zinc salt
must be replaced by the corresponding group. There is no
correlation between the coordination preference and the
(d, 2 H, Ph), 7.94 (d, 2 H, Ph), 8.21 (s, 1 H, CH=N), 11.52 (br. s,
1 H, NOH), 12.99 (br. s, 1 H, OH) ppm. 13C NMR ([D6]DMSO):
δ = 126.40 (Ph), 129.66 (Ph), 131.11 (C–C=NOH), 137.16 (C–
COOH), 147.51 (C=N), 166.90 ppm (COOH) ppm.
p-[(3-Hydroxy-1-methyl-2-butenylidene)amino]benzoic
Acid
(PSBCA-H): Acetylacetone (3.1 g, 31 mmol) was dissolved in eth-
anol (10 mL) and then added into a solution of p-aminobenzoic
acid (4.1 g, 30 mmol) in ethanol (40 mL). The solution was heated
at reflux for 5 h, and a clear yellow solution was obtained. The
solution was kept at room temperature for crystallization. The light
yellow crystals of PSBCA were isolated from the mother liquor,
1
washed by diethyl ether, and dried at 70 °C; yield 5.26 g (80%). H
acidity of the corresponding groups. Thus, steric effects and NMR ([D6]DMSO): δ = 2.02 (s, 3 H, N=C–CH3), 2.14 [s, 3 H,
C(OH)CH3], 5.33 (s, 1 H, CH), 7.26 (d, 2 H, Ph), 7.90 (d, 2 H,
Ph), 12.61 [s,1 H, C(CH3)OH], 12.81 (br. s, 1 H, COOH) ppm. 13C
NMR ([D6]DMSO): δ = 19.85 (N=C–CH3), 29.13 [C(OH)CH3],
99.28 (CH), 122.14 (Ph), 126.27 (C–N=C), 130.59 (Ph), 142.69 (C–
COO), 158.38 (C=N), 166.72 (COOH), 195.98 [C(CH3)OH] ppm.
the metal–ligand bond strength appear to be additional pa-
rameters that influence the substitution of the acetate
groups.
The coordination selectivity allowed us to prepare the
complexes Zn(XЈ–Y–X)2 (X = dangling organic group)
with XЈ = COO and X = oxime or β-ketoimine, as well as
X = salicylaldiminate and X = oxime. The combination of
carboxylate groups with salicylaldimine or amino groups
resulted in complexes in which both groups were coordi-
nated.
Dangling oxime groups are especially interesting because
they have been proven to react with metal alkoxides and
form stable oximate-substituted metal alkoxide deriva-
tives.[15] Reaction of the Zn(POBC)2 complex with Ti-
(OR)4 to give a bimetallic Zn/Ti single-source precursor
and its use to prepare ZnO/TiO2 mixed oxides will be re-
ported in a follow-up article.[8]
p-Salicyliden-p-aminobenzoic Acid (PSBC-H): 2-Hydroxybenzalde-
hyde (3.8 g, 31 mmol) was dissolved in ethanol (10 mL), and then
added into a solution of p-aminobenzoic acid (4.1 g, 30 mmol) in
ethanol (40 mL). A yellow solid precipitated immediately. After the
addition of ethanol (40 mL), the reaction mixture was heated at
reflux for 5 h. Then the precipitate was filtered, washed with several
portions of ethanol, and recrystallized from methanol. Dark yel-
low, needle-shaped crystals of PSBC-H were isolated, washed with
diethyl ether, and dried at 70 °C; yield 4.19 g (58%). 1H NMR
([D6]DMSO): δ = 12.97 (br. s, 1 H, COOH), 12.71 (br. s, 1 H,
C6H4OH), 9.00 (s, 1 H, N=CH), 8.04 (d, 2H), 7.72 (d, 1 H), 7.51
(d, 2H), 7.42 (d, 1 H), 7.04 (t, 2 H) ppm. 13C NMR ([D6]DMSO):
δ = 166.82 (COOH), 164.74 (CH=N), 160.27 (CPhOH), 152.13,
133.78, 132.57, 130.68, 128.76, 121.48, 119.26, 116.65 (CPh) ppm.
p-Salicyliden-p-aminoacetophenone Oxime (PSBO-H): A solution
of salicylaldenhyde (3.17 g, 26 mmol) in ethanol (50 mL) was added
dropwise to a solution of p-aminoacetophenone oxime (PABOM;
3.75 g, 25 mmol) in absolute ethanol (30 mL). The mixture was
heated to 60 °C with stirring, and a yellow solid precipitated. After
stirring overnight, the precipitate was filtered while hot, washed
with cold ethanol and diethyl ether, recrystallized from acetone/
water, and dried at 70 °C to a constant weight; yield 3.36 g (61%).
1H NMR ([D6]DMSO): δ = 13.03 (s, 1 H, C–OH), 11.26 (s, 1 H,
Experimental Section
Materials: Zinc acetate dihydrate, p-carboxybenzaldehyde, sodium
acetate, hydroxylamine hydrochloride, p-aminoacetophenone, p-
aminobenzoic acid (PABC-H), salicylaldehyde (2-hydroxybenzalde-
hyde), and acetylacetone were used as received. The solvents used
in the reactions were of analytical reagent grade and dried using
standard procedures.
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J. Yang, M. Puchberger, R. Qian, C. Maurer, U. Schubert
to-detector distance of 5.0 cm using graphite-monochromated Mo-
FULL PAPER
N–OH), 8.98 (s, 1 H, N=CH), 7.71 (d, 2 H, Ph), 7.64 (d, 1 H,
C6H4), 7.44 (d, 2 H, C6H4), 7.38 (d, 1 H, C6H4), 6.98 (t, 2 H, Kα radiation (λ = 71.073 pm). Data were collected with φ and ω
C6H4), 2.16 (s, 3 H, CH3) ppm. 13C NMR ([D6]DMSO): δ = 163.4
(N=CH), 160.3 (C–OH), 152.4 (C=N), 148.1, 135.5, 133.4, 132.5,
126.6, 121.4, 119.3, 119.1, 116.6 (C6H4), 11.4 (CH3) ppm.
scans and a 0.5° frame width. The data were corrected for polariza-
tion and Lorentz effects, and an empirical absorption correction
(SADABS[16]) was employed. The cell dimensions were refined with
all unique reflections. SAINT PLUS software[17] was used to inte-
grate the frames. Details of the X-ray investigations are given in
Table 1.
Zn(POBC)2: A solution of Zn(OAc)2·2H2O (1.09 g, 5 mmol) in eth-
anol (20 mL) was added to a solution of POBC-H (10 mmol) in
ethanol (40 mL) at 50 °C. The solution became clear after stirring
for 2 h. The solvent was then removed under reduced pressure, and
a white powder was obtained. The powder was extracted several
times with diethyl ether and then dried at 120 °C to constant
Table 1. Crystallographic data for [Zn2(OAc)(OOC–C6H4–NH2)3]ϱ.
Empirical formula
Mr
Crystal system
Space group
a [pm]
b [pm]
c [pm]
C48H48N6O17Zn4
1242.4
monoclinic
C2/c
2407.0(1)
1417.02(7)
1852.8(1)
126.991(2)
5047.4(5)
4
1
weight; yield 1.76 g (89%). H NMR ([D6]DMSO): δ = 7.63 (d, 2
H, Ph), 7.94 (d, 2 H, Ph), 8.18 (s, 1 H, CH=N), 11.37 (br. s, 1 H,
OH) ppm. 13C NMR ([D6]DMSO): δ = 125.91 (Ph), 129.83 (Ph),
135.32 (C–COO), 147.80 (C=N), 171.10 (COO) ppm.
C16H12N2O6Zn (393.66): calcd. C 48.77, H 3.05, N 7.11; found C
47.47, H 3.32, N 6.05. TGA weight loss: calcd. (%) for ZnO 79.3;
found 80.1.
β [°]
V [pm3]·106
Z
Zn(PSBCA)2: A solution of Zn(OAc)2·2H2O (1.09 g, 5 mmol) in
ethanol (20 mL) was added to a hot solution of PSBCA-H
(10 mmol) in ethanol (40 mL) at 50 °C. A colorless solid precipi-
tated immediately. After further stirring for 2 h, the precipitate was
filtered while hot, washed with cold ethanol and diethyl ether, and
then dried at 120 °C to constant weight; yield 1.57 g (62%). 1H
NMR ([D6]DMSO): δ = 2.01 (s, 3 H, N=C–CH3), 2.10 [s, 3 H,
C(OH)CH3], 5.29 (s, 1 H, CH), 7.20 (d, 2 H, Ph), 7.93 (d, 2 H,
Ph), 12.58 (s,1 H, OH) ppm. 13C NMR ([D6]DMSO): δ = 19.72
(N=C–CH3), 29.05 [C(OH)CH3], 98.54 (CH), 122.22 (Ph), 130.68
(Ph), 140.95 (C–COO), 158.96 (C=N), 170.87 (COO), 195.53
[C(OH)CH3] ppm. C24H24N2O6Zn (501.84): calcd. C 57.39, H 4.78,
N 5.58; found C 56.96, H 4.92, N 5.42. TGA weight loss: calcd.
(%) for ZnO 83.8; found 82.7.
Dcalcd. [Mgm–3]
μ [mm–1]
Crystal size [mm]
1.635
1.957
0.20ϫ0.20ϫ0.20
Measured, unique reflections 21773, 4455
θmax [°]
25.00
R1, wR2 [IϾ2σ(I)]
Reflections/parameters
Weighting scheme
0.0464, 0.1631
4455/384
w = 1/[σ2(F02) + (0.1146P)2 +
16.3637P[a]
δρmax., δρmin [eÅ–3]
[a] P = (F2o +2F2c)/3.
3.481, –0.466
The structures were solved by direct methods (SHELXS97[18]). Re-
finement was performed by the full-matrix least-squares method on
the basis of F2 (SHELXL97) with anisotropic thermal parameters
for all non-hydrogen atoms. Hydrogen atoms were inserted in cal-
culated positions and refined riding with the corresponding atom;
those bonded to oxygen and nitrogen atoms were identified in the
electron density map.
Reaction of Zinc Acetate with PSBC-H: The procedure was the
same as for the synthesis of Zn(PSBCA)2. A yellow precipitate was
obtained; yield 1.81 g (66%). 1H NMR ([D6]DMSO): δ = 12.89 (br.
s, 1 H, CPh–OH), 9.00 and 8.71 (s, 1 H, N=CH), 8.00 (d) and 7.7–
6.5 ppm (6 H, C6H4) ppm. 13C NMR ([D6]DMSO): δ = 170.98
(COO), 164.20 and 168.88 (C=N), 160.28 (CPhOH), 150.93 (CPhN),
137.5–116.0 (C6H4) ppm. C56H38N4O12Zn2 [Zn(PSBC)2]: calcd. C
61.55, H 3.48, N 5.13; found C 59.25, H 3.65, N 5.01. TGA weight
loss: calcd. (%) for ZnO 85.1; found 85.0.
CCDC-883699 contains the supplementary crystallographic data
for this paper. These data can be obtained free of charge from The
Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/
data_request/cif.
Supporting Information (see footnote on the first page of this arti-
Zn2(OAc)(OOC–C6H4–NH2)3: Zn(OAc)2·2H2O (0.55 g, 2.5 mmol)
was added to a solution of PABC-H (1.37 g, 10 mmol) in ethanol
(20 mL). After stirring for 10 min, a colorless solid precipitated.
The solution was sealed and kept for 4 weeks, during which time
the precipitate transformed into light yellow crystals; yield 0.32 g
(43%). 1H NMR ([D6]DMSO): δ = 7.64 (d, 2 H, Ph), 6.51 (d, 2 H,
Ph), 5.51 (s, 2 H, NH2), 1.82 ppm (s, 1 H, CH3) ppm.
1
cle): H and 13C NMR spectra, as well as IR spectra and TGA of
all complexes.
Acknowledgments
This work was supported by the Austrian Fonds zur Förderung der
wissenschaftlichen Forschung (FWF) (project no. P22536).
Zn(PSBO)2: The procedure was the same as for the synthesis of
Zn(PSBCA)2. A light yellow precipitate was obtained; yield 1.74 g
1
(61%). H NMR ([D6]DMSO): δ = 11.21 (s, 1 H, OH), 8.80 (s, 1
[1] Review article: M. Veith, J. Chem. Soc., Dalton Trans. 2002,
2405–2412.
H, N=CH), 7.60 (d, 2 H), 7.50 (d, 1 H), 7.37 (d, 1 H), 7.31 (d, 2
H), 6.73 (d, 1 H), 6.66 (d, 1 H), 2.09 (s, 3 H, CH3) ppm. 13C NMR
([D6]DMSO): δ = 170.8 (N–CH), 170.1 (C–OH), 152.1 (C=N),
148.5, 137.5, 135.9, 135.4, 126.8, 122.7, 121.3, 118.7, 114.6 (C6H4),
11.3 (CH3) ppm. C30H26N4O4Zn (571.94): calcd. C 62.94, H 4.55,
N 9.79; found C 63.23, H 4.58, N 9.73. TGA weight loss: calcd.
(%) for ZnO 85.8; found 85.3.
[2] U. Schubert, S. Amberg-Schwab, B. Breitscheidel, Chem. Ma-
ter. 1989, 1, 576–578; B. Breitscheidel, J. Zieder, U. Schubert,
Chem. Mater. 1991, 3, 559–566; C. Lembacher, U. Schubert,
New J. Chem. 1998, 22, 721–724; G. Trimmel, U. Schubert, J.
Non-Cryst. Solids 2001, 296, 188–200; G. Trimmel, C. Lem-
bacher, G. Kickelbick, U. Schubert, New J. Chem. 2002, 26,
759–765.
[3] W. Rupp, N. Hüsing, U. Schubert, J. Mater. Chem. 2002, 12,
2594–2596; V. Torma, H. Peterlik, U. Bauer, W. Rupp, N.
Hüsing, S. Bernstorff, M. Steinhart, G. Goerigk, U. Schubert,
X-ray Structure Analysis: Single-crystal X-ray diffraction experi-
ments were performed at 100 K with a Bruker-AXS SMART
APEX II diffractometer with a CCD area detector and a crystal-
6
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Job/Unit: I20558
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Date: 15-08-12 15:07:32
Pages: 8
Zinc(II) Complexes with Dangling Functional Organic Groups
Chem. Mater. 2005, 17, 3146–3153; H. Peterlik, H. Rennhofer,
V. Torma, U. Bauer, M. Puchberger, N. Hüsing, S. Bernstorff,
U. Schubert, J. Non-Cryst. Solids 2007, 353, 1635–1644.
Review articles:U. Schubert, Adv. Eng. Mater. 2004, 6, 173–
176; U. Schubert, Polym. Int. 2009, 58, 317–322.
S. C. Warren, M. R. Perkins, A. M. Adams, M. Kaperman,
A. A. Burns, H. Arora, E. Herz, T. Suteewong, H. Sai, Z. Li,
J. Werner, J. Song, U. Werner-Zwanziger, J. W. Zwanziger, M.
Grätzel, F. J. DiSalvo, U. Wiesner, Nat. Mater. 2012, 11, 460–
467.
U. Schubert, S. Tewinkel, F. Möller, Inorg. Chem. 1995, 34,
995–997; U. Schubert, S. Tewinkel, R. Lamber, Chem. Mater.
1996, 8, 2047–2055.
[12] T. S. B. Baul, C. Masharing, S. Basu, C. Pettinari, E. Rivarola,
S. Chantrapromma, H. K. Fun, Appl. Organomet. Chem. 2007,
22, 114–121.
[13] I. R. Amirasanov, G. N. Nadzhafov, B. T. Usubaliev, A. A.
Musaev, E. M. Movsumov, K. S. Mamedov, Zh. Strukt. Khim.
1980, 21, 140–145; L. Li, D. Sun, Z. Wang, X. Song, S. Sun,
Solid State Sci. 2009, 11, 1040–1043.
[14] Q. Wie, D. Yang, T. E. Larson, T. L. Kinnibrugh, R. Zou, N. J.
Henson, T. Timofeeva, H. Xu, Y. Zhao, B. R. Mattes, J. Mater.
Chem. 2012, 22, 10166–10171.
[15] S. O. Baumann, M. Bendova, H. Fric, M. Puchberger, C. Visi-
nescu, U. Schubert, Eur. J. Inorg. Chem. 2009, 3333–3340; S. O.
Baumann, M. Puchberger, U. Schubert, Dalton Trans. 2011,
40, 1401–1406; S. O. Baumann, M. Bendova, R. Potzmann, M.
Puchberger, U. Schubert, Eur. J. Inorg. Chem. 2011, 573–580.
[16] SADABS, Bruker AXS Inc., Madison, Wisconsin, USA, 2001.
[17] SAINT PLUS, Bruker AXS Inc., Madison, Wisconsin, USA,
2007.
[4]
[5]
[6]
[7]
O. Metelkina, U. Schubert, Monatsh. Chem. 2003, 134, 1065–
1069.
[8] J. Yang, J. Akbarzadeh, C. Maurer, H. Peterlik, U. Schubert,
J. Mater. Chem., submitted.
[9] U. Schubert, J. Mater. Chem. 2005, 15, 3701–3715; U. Schu-
[18] G. M. Sheldrick, SHELXS-97, Program for Crystal Structure
Determination, University of Göttingen, Göttingen, Germany,
1997.
bert, Acc. Chem. Res. 2007, 40, 730–737.
[10] E. Canpolat, M. Kaya, Pol. J. Chem. 2005, 79, 959–965.
[11] M. Melnik, K. Györyová, J. Skorsˇepa, C. E. Holloway, J. Co-
ord. Chem. 1995, 35, 179–279.
Received: May 24, 2012
Published Online: ᭿
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© 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
7

Job/Unit: I20558
/KAP1
Date: 15-08-12 15:07:32
Pages: 8
J. Yang, M. Puchberger, R. Qian, C. Maurer, U. Schubert
FULL PAPER
Precursor Chemistry
Zinc(II) complexes with dangling func-
tional organic groups were synthesized by
reaction of zinc acetate with a series of bi-
functional p-substituted benzene deriva-
tives. Selective coordination to carboxylate
groups was observed when the second func-
tional group was an oxime or β-ketoimine
group.
J. Yang, M. Puchberger, R. Qian,
C. Maurer, U. Schubert* ................... 1–8
Zinc(II) Complexes with Dangling Func-
tional Organic Groups
Keywords: Coordination polymers / Zinc /
Carboxylate ligands / Schiff bases
8
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