Novel Complexes of Ligands Containing Phenol and Alcohol Groups: From Polynuclear Cluster, 1D Coordination Polymer to 2D Supramolecular Assemblies

Article abstract of DOI:10.1002/ejic.200300384

A series of Co^II, Cu^II, Zn^II, Ag ^I and mixed-valence cobalt complexes 1-9 with tridentate and tetradentate chelating ligands containing oxygen-bridging and hydrogen-bonding groups have been synthesized, four of which have been structurally characterized: [Co₆L₆¹(OH)(H₂O) ₃]Cl₂·10H₂O (1) [H₂L ¹ = N-(2-hydroxybenzyl)ethanolamine] is a hexanuclear Co ^III₃Co^II₃ complex, with a core of quadruple face-sharing defective cubane-like units; [CuNaL²(ClO ₄)]∞ (3) [H₂L² = N,N'-bis(2-hyroxybenzyl)ethylenediammel is a μ₃-phenoxo-and μ₄-perchlorato-bridged 1D heterometallic Cu^IINa ^I coordination polymer; the coordination moieties of [CuL ³]₄·4H₂O (6) [H₂L ³ = N,N'-bis(2-hyroxy-5-methylbenzyl)ethylenediamine] form a 2D hydrogen-bonded network structure of monophenoxo-bridged dimeric moieties; and the molecules of [Ag(H₂L²)(HL²)] (9) are connected to give an undulated 2D structure, consisting of hydrogen-bonded hexagonal units. The variety of these structures is discussed on the basis of the stereoelectronic preferences of the metal atoms, hydrogen bonds, disposition of the bridging groups, steric effect, and conformational flexibility of the ligands. Variable-temperature magnetic properties of 1 and 6 are also reported. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003).

Full text of DOI:10.1002/ejic.200300384

FULL PAPER
Novel Complexes of Ligands Containing Phenol and Alcohol Groups: From
Polynuclear Cluster, 1D Coordination Polymer to 2D Supramolecular
Assemblies
Yongshu Xie,[a] Qingliang Liu,*[a] Hui Jiang,[a] and Jia Ni[a]
Keywords: Copper / Cobalt / Silver / Coordination polymers / N,O ligands
A series of CoII, CuII, ZnII, AgI and mixed-valence cobalt
amine] form a 2D hydrogen-bonded network structure of
monophenoxo-bridged dimeric moieties; and the molecules
complexes 1−9 with tridentate and tetradentate chelating li-
gands containing oxygen-bridging and hydrogen-bonding of [Ag(H2L2)(HL2)] (9) are connected to give an undulated 2D
groups have been synthesized, four of which have been
structurally characterized: [Co6L16(OH)(H2O)3]Cl2·10H2O (1)
[H2L1 = N-(2-hydroxybenzyl)ethanolamine] is a hexanuclear
structure, consisting of hydrogen-bonded hexagonal units.
The variety of these structures is discussed on the basis of
the stereoelectronic preferences of the metal atoms, hydro-
gen bonds, disposition of the bridging groups, steric effect,
and conformational flexibility of the ligands. Variable-tem-
perature magnetic properties of 1 and 6 are also reported.
CoIII3CoII complex, with a core of quadruple face-sharing
3
defective cubane-like units; [CuNaL2(ClO4)]ϱ (3) [H2L2
=
N,NЈ-bis(2-hyroxybenzyl)ethylenediamine] is a µ3-phenoxo-
and µ4-perchlorato-bridged 1D heterometallic CuIINaI coor-
dination polymer; the coordination moieties of [CuL3]4·4H2O
(6) [H2L3 = N,NЈ-bis(2-hyroxy-5-methylbenzyl)ethylenedi- Germany, 2003)
( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Introduction
of the corresponding Schiff bases. The phenol and the alk-
Assemblies of polynuclear complexes, coordination poly-
mers and hydrogen-bonded supramolecular coordination
networks have potential applications and are aesthetically
appealing.[1Ϫ3] The assemblies of these frameworks are in-
fluenced by factors such as the structures of the ligands
and the stereoelectronic preferences of the metal ions.[4] The
assembly of metal atoms with chelating ligands containing
endogenous bridging atoms is one promising route to unex-
pected, interesting coordination structures, wherein the
most commonly utilized bridging atoms are from car-
boxylate functionalities.[5] In contrast, chelating ligands
containing phenol groups have been much less explored.[6]
We demonstrate here the successful construction of various
novel coordination architectures, utilizing chelating ligands
containing phenol and/or alkoxy groups (H2L1 Ϫ H2L3)
(Scheme 1), which have been synthesized by the reduction
oxy groups can act as bridging and hydrogen-bonding
functionalities. Compared with the corresponding Schiff
bases, H2L1ϪH2L3 have greater flexibility and confor-
mational freedom. In addition, the amino groups, which are
absent in the Schiff bases, may also affect the structures of
the products via intermolecular hydrogen bonds. Conse-
quently, these ligands may be promising for the construc-
tion of novel coordination assemblies, and so we have inves-
tigated several of their metal complexes. Our interest in li-
gands containing phenoxy and alkoxy groups also lie in
their relevance to the coordination environments of active
sites of metalloenzymes.[7]
Divalent metals with pseudooctahedral coordination
preferences, namely, CoII, CuII and ZnII, have been used for
the synthesis of the complexes. For comparison, the soft
metal AgI, which has a tetrahedral preference, has also been
used. Thus, a series of CoII, CuII, ZnII, AgI and mixed-
valence cobalt complexes have been synthesized, four of
which have been characterized by X-ray crystal analyses to
reveal structures varying from hexanuclear cluster, 1D bi-
Scheme 1. Molecular structures of the ligands (H2L1: n ϭ 1, H2LЈ: metallic coordination polymers to 2D supramolecular as-
n ϭ 2, H2L2: R ϭ H, H2L3: R ϭ CH3)
semblies. The structures of the complexes are discussed on
the basis of various structure-directing factors, including
[a]
Department of Chemistry, University of Science and
the metal coordination preferences, hydrogen bonds, bridg-
ing groups, steric effect, and conformational flexibility of
the ligands. Variable-temperature magnetic properties of
two of the complexes are also reported. The results ob-
Technology of China,
Hefei, 230026, P. R. China
E-mail: yshxie@ustc.edu.cn
Supporting information for this article is available on the
WWW under http://www.eurjic.org or from the author.
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DOI: 10.1002/ejic.200300384
Eur. J. Inorg. Chem. 2003, 4010Ϫ4016

Novel Complexes of Ligands Containing Phenol and Alcohol Groups
FULL PAPER
tained are valuable for the design and synthesis of further electron. The EPR parameters (3: g// ϭ 2.229, gЌ ϭ 2.004,
such novel complexes.
A// ϭ 186.4 G, Aiso ϭ 85.7 G; 6: g// ϭ 2.231, gЌ ϭ 2.006,
A// ϭ 188.7 G) are indicative of tetragonal coordination en-
1
2
Ϫy
2
vironments with (dx
)
ground states for complexes 3
and 6.[8]
Results
The electronic spectra of the copper and cobalt com-
plexes in DMF (Table 1) exhibit intraligand transitions, and
dϪd transitions in addition to strong LMCT bands, con-
firming the coordination of the deprotonated phenoxy
groups.
Structural Results: The crystal structure of 1 consists of
a discrete [Co6L16(OH)(H2O)3]2ϩ hexameric entity (Fig-
ure 2, a, Table S1 of the Supporting Information; see also
the footnote on the first page of this article), two noncoor-
dinated chloride counter anions, and ten water molecules of
crystallization. Bond lengths, charge balance considerations
Synthesis and Spectroscopic Results: To promote the de-
protonation and subsequent coordination of the phenol and
the alkoxy groups, complexes 1Ϫ8 were synthesized at alka-
line pH by the addition of stoichiometric aqueous NaOH
solution. For the AgI complex (9), Ag2O precipitates upon
the addition of NaOH, and the direct reaction of H2L2 with
AgNO3 in methanol resulted in a white precipitate of 9,
which was gradually dissolved by the addition of an excess
of concentrated ammoniacal solution. Probably, the coordi-
nated H2L2 is initially displaced by NH3, which then evap-
orates to allow H2L2 to reform complex 9, which gradually
crystallized. Attempts to synthesize AgI complexes of H2L1
and H2L3 gave only the free ligands, possibly due to the
weak coordinating abilities of the ligands and the instability
of the resulting complexes.
In the IR spectra of complexes 1Ϫ8, the coordination of
the phenol groups is exhibited by the shifting of ν(CϪO) to
higher wavenumbers. For complexes 3Ϫ5, and 7, the intense
bands near 1100 cmϪ1 show distinct splittings, indicative of
Ϫ
coordinated ClO4
.
Isotropic EPR spectra of complex 3 and 6 in DMF con-
taining four copper hyperfine lines are observed at 300 K
(Figure 1), while the spectra at 100 K have axial symmetries,
with four hyperfine peaks in the parallel region derived
from the coupling of the copper nucleus and the unpaired
Figure 2. Complementary views of the structure of 1 showing 20%
probability displacement ellipsoids. H atoms have been omitted
for clarity
Figure 1. EPR spectra of the complexes in DMF: (a) 3, 300 K; (b)
6, 300 K; (c) 3, 100 K; (d) 6, 100 K
Table 1. Electronic spectra of the complexes in DMF
Complexes
π Ǟ π*
λmax/nm (ε/dm3·molϪ1·cmϪ1
n Ǟ π*
)
L Ǟ M
d Ǟ d
1
3
4
6
7
264 (9.63 ϫ 103)
290 (5.30 ϫ 103)
290 (1.37 ϫ 104)
252 (2.46 ϫ 104)
286 (5.33 ϫ 103)
247 (1.42 ϫ 104)
358 (1.35 ϫ 103)
390 (1.22 ϫ 103)
373 (3.01 ϫ 103)
340 (704), 398 (781)
384 (1.55 ϫ 103)
598 (100)
605 (283)
584 (323)
598 (296)
592 (205)
268 (6.00 ϫ 103)
213 (1.51 ϫ 104)
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Y. Xie, Q. Liu, H. Jiang, J. Ni
FULL PAPER
and magnetic measurements (vide infra) reveal that the
The asymmetric unit of 3 (Table 2) consists of one CuII,
Ϫ
three inner cobalt atoms are CoII, and the outer ones are one (L2)2Ϫ, one ClO4 anion and two partially occupied
CoIII. Each CoIII has an N2O4 ligation, namely the two NaI atoms lying on the special positions of the inversion
phenoxo, two alkoxo and two amino groups of two fac- centers with occupation factors of 50%. Thus, 3 can be
(L1)2Ϫ ligands. The phenoxo and alkoxo groups of the understood as a 1:1 adduct of CuL2 with NaClO4, wherein
(L1)2Ϫ ligands, together with a µ3-hydroxo ligand, bridge (L2)2Ϫ coordinates with CuII as a tetradentate ligand in the
the six cobalt atoms, resulting in, apparently, the first equatorial plane. The neighboring CuL2 units are arranged
Co6O10 face-sharing quadruple defective cubane-like com- in an alternating up/down-up/down mode, and act as neu-
plex. The whole hexameric entity adopts a crown shape tral ligands to coordinate NaI atoms via the phenoxo O
(Figure 2, b), with the three phenyl rings at the upper rim atoms, affording an infinite zigzag arrangement of alternat-
tilted inward, and the phenyl rings at the lower rim tilted ing CuII and NaI centers along the a axis (Figure 4). The
outward. According to the ‘‘Harris’’ notation,[9] the upper final coordination polymer involves phenoxo and perchlor-
(L1)2Ϫ and lower (L1)2Ϫ ligands are involved in 321221311 ato groups in the unusual µ3- and µ4-bridging modes,
and 311312311 bridging modes, respectively (Figure 3). The respectively, and the final coordination geometries around
CoIIIϪN and CoIIIϪO distances are in the ranges CuII and NaI are elongated octahedral and irregular octa-
˚
1.944(7)Ϫ1.980(7) and 1.862(5)Ϫ1.956(5) A, respectively. hedral, respectively. This appears to be the first coordi-
The
CoIIϪO
distances
are
in
the
range nation polymer of H2L2.[10]
II
II
˚
1.991(5)Ϫ2.286(5) A, and the Co ϪOϪCo angles are
94.44(19)Ϫ107.8(3)°, with CoII···CoII separations of 3.240,
˚
3.253 and 3.270 A, respectively.
Figure 3. Bridging modes of (L1)2Ϫ in complex 1
Table 2. Selected bond lengths and angles for 3
Figure 4. One-dimensional linear structure of 3, showing the atom
labeling scheme at the 20% probability level with H atoms omitted
for clarity
˚
Bond lengths (A)
Cu(1)ϪO(2)
Cu(1)ϪO(6)
Cu(1)ϪN(2)
Na(1)ϪO(1)
Na(1)ϪO(2)
Na(2)ϪO(2)
1.914(3) Cu(1)ϪO(1)
2.640(5) Cu(1)ϪO(3)[a]
2.005(5) Cu(1)ϪN(1)
2.433(4) Na(1)ϪO(6)
2.616(4) Na(2)ϪO(3)[b]
2.453(4) Na(2)ϪO(1)
1.924(4)
2.672(5)
2.007(4)
2.450(5)
2.327(5)
The asymmetric unit of crystal 6 (Table 3) consists of four
crystallographically independent, and chemically similar,
CuL3 moieties and four water molecules of crystallization.
In each CuL3 moiety, the tetradentate (L3)2Ϫ ligand is coor-
2.569(4) dinated in the basal plane of CuII. The four CuL3 units are
connected into two dimers via axial monophenoxo bridg-
Bond angles (°)
O(2)ϪCu(1)ϪO(1)
O(1)ϪCu(1)ϪN(2)
O(1)ϪCu(1)ϪN(1)
84.4(2) O(2)ϪCu(1)ϪN(2)
175.7(2) O(2)ϪCu(1)ϪN(1)
93.9(2) N(2)ϪCu(1)ϪN(1)
95.6(2)
176.4(2)
86.4(2)
96.66(14)
83.34(14)
ing, with CuϪO bridging distances of 2.562(2) and
˚
2.490(3) A, and CuϪOϪCu angles of 98.49(10) and
O(1)ϪNa(1)ϪO(1)[b] 180.0
O(1)ϪNa(1)ϪO(6)[b]
103.56(10)°, respectively. The dimers are further connected
by multiple hydrogen bonds, i.e., every two water molecules
are connected via hydrogen bonds to form a structural unit,
which in turn connects the amino and the phenoxo func-
tionalities to form a 2D sheet approximately along the ab
O(1)[b]ϪNa(1)ϪO(6)[b] 83.34(14) O(1)ϪNa(1)ϪO(6)
O(1)[b]ϪNa(1)ϪO(6)
O(1)ϪNa(1)ϪO(2)
96.66(14) O(6)[b]ϪNa(1)ϪO(6) 180.000(1)
61.28(12) O(1)[b]ϪNa(1)ϪO(2) 118.72(12)
O(6)[b]ϪNa(1)ϪO(2) 105.80(13) O(6)ϪNa(1)ϪO(2)
74.20(13)
O(1)ϪNa(1)ϪO(2)[b] 118.72(12) O(1)[b]ϪNa(1)ϪO(2)[b] 61.28(12)
O(6)[b]ϪNa(1)ϪO(2)[b] 74.20(13) O(6)ϪNa(1)ϪO(2)[b] 105.80(13) plane (Figure 5). In the final structure, half of the water
O(2)ϪNa(1)ϪO(2)[b] 180.0
O(3)[b]ϪNa(2)ϪO(3)[a] 180.000(1)
molecules are quadruple-connecting, and the other half are
triple-connecting. Interestingly, a nearly planar six-mem-
bered ring is formed by Cu(4), O(7), O(8), and the water
molecule via hydrogen bonds.
O(3)[b]ϪNa(2)ϪO(2)
O(3)[a]ϪNa(2)ϪO(2)
96.6(2) O(3)[b]ϪNa(2)ϪO(2)[c] 83.4(2)
83.4(2) O(3)[a]ϪNa(2)ϪO(2)[c] 96.6(2)
O(2)ϪNa(2)ϪO(2)[c] 180.000(1) O(3)[b]ϪNa(2)ϪO(1)[c] 78.91(14)
O(3)[a]ϪNa(2)ϪO(1)[c] 101.09(14) O(2)ϪNa(2)ϪO(1)[c] 118.28(11)
O(2)[c]ϪNa(2)ϪO(1)[c] 61.72(11) O(3)[b]ϪNa(2)ϪO(1) 101.09(14)
In the crystal structure of the AgI complex 9 (Figure 6,
and Table 4), AgI is coordinated with four N atoms from
two L2 ligands, with one ligand in the protonated H2L2
form, and the other in mono-deprotonated (HL2)Ϫ. The
noncoordinated phenol and phenolate groups are involved
O(3)[a]ϪNa(2)ϪO(1)
78.91(14) O(2)ϪNa(2)ϪO(1)
61.72(11)
O(2)[c]ϪNa(2)ϪO(1) 118.28(11) O(1)[c]ϪNa(2)ϪO(1) 180.0
[a]
Symmetry transformations used to generate equivalent atoms:
Ϫ1 ϩ x, y, z. 2 Ϫ x, 2 Ϫ y, 2 Ϫ z. [c] 1 Ϫ x, 2 Ϫ y, 2 Ϫ z.
[b]
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Novel Complexes of Ligands Containing Phenol and Alcohol Groups
FULL PAPER
Table 3. Selected bond lengths and angles for 6
˚
Bond lengths (A)
Cu(1)ϪO(1)
Cu(1)ϪN(1)
Cu(2)ϪO(3)
Cu(2)ϪN(4)
Cu(3)ϪO(5)
Cu(3)ϪN(5)
Cu(4)ϪO(8)
1.911(2) Cu(1)ϪO(2)
1.989(3) Cu(1)ϪN(2)
1.925(2) Cu(2)ϪO(4)
2.016(3) Cu(2)ϪN(3)
1.918(2) Cu(3)ϪO(6)
1.990(3) Cu(3)ϪN(6)
1.923(3) Cu(4)ϪO(7)
2.009(3) Cu(4)ϪN(7)
2.490(2) Cu(2)ϪO(1)
1.913(2)
2.005(3)
1.952(3)
2.019(3)
1.919(2)
1.994(3)
1.953(2)
2.027(3)
2.562(3)
Cu(4)ϪN(8)
Cu(4)ϪO(6)[a]
Bond Angles (°)
O(1)ϪCu(1)ϪO(2)
O(2)ϪCu(1)ϪN(1)
O(2)ϪCu(1)ϪN(2)
O(3)ϪCu(2)ϪO(4)
O(4)ϪCu(2)ϪN(4)
O(4)ϪCu(2)ϪN(3)
O(5)ϪCu(3)ϪO(6)
O(6)ϪCu(3)ϪN(5)
O(6)ϪCu(3)ϪN(6)
O(8)ϪCu(4)ϪO(7)
O(7)ϪCu(4)ϪN(8)
O(7)ϪCu(4)ϪN(7)
88.88(10) O(1)ϪCu(1)ϪN(1)
94.06(11)
169.22(11) O(1)ϪCu(1)ϪN(2) 167.52(12)
92.85(11) N(1)ϪCu(1)ϪN(2) 86.52(12)
89.01(10) O(3)ϪCu(2)ϪN(4) 177.63(12)
162.48(12) O(3)ϪCu(2)ϪN(3)
92.12(11) N(4)ϪCu(2)ϪN(3)
89.52(10) O(5)ϪCu(3)ϪN(5)
166.20(11) O(5)ϪCu(3)ϪN(6) 167.66(11)
93.90(11) N(5)ϪCu(3)ϪN(6)
89.23(11) O(8)ϪCu(4)ϪN(8)
93.81(11)
85.74(12)
93.57(11)
85.93(12)
94.19(12)
160.38(11) O(8)ϪCu(4)ϪN(7) 177.69(11)
92.40(11) N(8)ϪCu(4)ϪN(7)
84.81(12)
Cu(4)ϪO(6)[a]ϪCu(3)[a] 103.56(11) Cu(2)ϪO(1)ϪCu(1) 98.49(10)
[a]
Symmetry transformations used to generate equivalent atoms: x,
Ϫ1 ϩ y, z.
Figure 6. Molecular structure and undulated 2-D sheet of complex
9, approximately along the bc plane
Table 4. Selected bond lengths and angles for 9
˚
Bond lengths (A)
Ag1ϪN3
Ag1ϪN1
2.298(3)
2.410(2)
Ag1ϪN2
Ag1ϪN4
2.331(2)
2.424(2)
Bond Angles (deg)
N3ϪAg1ϪN2
N2ϪAg1ϪN1
N2ϪAg1ϪN4
135.88(11)
76.48(9)
118.59(9)
N3ϪAg1ϪN1
N3ϪAg1ϪN4
N1ϪAg1ϪN4
130.47(9)
77.94(8)
124.34(8)
in intermolecular hydrogen bonds, resulting in an undulated
2D network of hexagonal units; each corner of the hexa-
gons is occupied by an AgI atom. Interestingly, the hydro-
˚
gen bond O3···H···O4A [O3···O4A 2.444(3) A, bond angle
of 173.56°] can be regarded as a (Ϫ)CAHB type; such
strong bonds have been observed mostly in systems con-
taining carboxylate and carboxylic acid molecules.[11] Their
occurrence between the phenolate and the phenol groups is
rather unusual.
Magnetic Studies: The magnetic behavior of 1 and 6 was
studied. With the decreasing of temperature, the observed
χMT for 1 (Figure S1, see Supporting Information) gradu-
ally decreases from 8.47 (300 K) to 3.02 cm3·molϪ1·K at
5 K, which is characteristic of an antiferromagnetically cou-
Figure 5. Molecular structure and 2-D sheet of complex 6, approxi-
mately along the ab plane
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Y. Xie, Q. Liu, H. Jiang, J. Ni
FULL PAPER
pled CoII moiety, and is consistent with the crystal struc- can be anticipated if similar polynuclear clusters of these
3
ture (vide supra). For 6, however, χMT (Figure S2, Support- two ligands are formed. Thus, the 1D heterometallic coordi-
ing Information) increases slowly from 0.633 (300 K) to a nation polymer and the weak axial monophenoxo-bridged
maximum of 0.737 cm3·molϪ1·K at 9 K, and then de- binuclear moieties are seen for 3 and 6, respectively. For
creased to 0.730 cm3·molϪ1·K at 5 K, indicating a net weak [CoL2NaClO4]·CH3OH (4), [ZnL2·NaClO4]·H2O (5), and
ferromagnetic interaction between the CuII centers due to [CoL3NaClO4]·1.5H2O (7), structures similar to that of 3
the coexistence of ferro- and antiferromagnetic interactions, may also be assigned.
which can be assigned to interactions within the dimers
For the complex of H2L2 with the soft AgI atom, which
with the bridging angles of 98.49° and 103.56° (vide su- prefers a tetrahedral coordination, the ligand acts in biden-
pra), respectively.
tate mode in complex 9 via coordination of the N atoms.
H2L2 is usually a tetradentate ligand,[10] but the unusual
bidentate coordination mode can be rationalized by the
tendency of AgI to coordinate with N rather than O atoms,
and by the tetrahedral preference of four-coordinate AgI,
Discussion
The unsymmetrical tridentate ligand H2L1 contains both which cannot be satisfied without great strain if the ligand
phenol and alkoxy groups. It forms the hexanuclear cluster coordinates in a tetradentate mode. Thus, the 1:2 complex
1, with both the phenoxy and alkoxy groups involved in [Ag(H2L2)(HL2)] is formed, irrespective of the molar ratio
bridging. A few polynuclear clusters have also been re- of the reagents, and the noncoordinated phenol groups are
ported for similar tridentate unsymmetrical ligands.[12,13] involved in intermolecular hydrogen bonds, resulting in an
While the number of polynuclear transition metal com- undulated 2D network.
plexes reported continues to grow rapidly, some nuclearities
The rich coordination modes of the ligands can also be
remain rare. Only a few hexanuclear cobalt complexes con- related to their conformational flexibility, as evidenced by
taining N or O donors have been reported,[14] along with the large values of 36.9°, 52.0° and 84.9° for the dihedral
some larger cobalt cages[15] and a number of hexanuclear angles between the two mean planes through the aromatic
cobalt-chalcogen clusters.[16] The occurrence of complex 1 rings of the same ligands in complexes 3, 6, and 9, respec-
may be related to the properly disposed bridging functional- tively. In contrast to the approximately planar trinuclear
ities from the (L1)2Ϫ ligand and the suitable chelate ring salen adduct [Cu(salen)]2NaClO4,[17] the totally different ar-
size. In contrast to the fac-coordination mode of (L1)2Ϫ in rangement in complex 3 provides a perfect match between
1, in the related tetranuclear cubane CuII complex [Cu4LЈ4] the coordination environment provided by the donor atoms
[LЈ ϭ N-(2-hydroxybenzyl)propanolamine, Scheme 1],[12] of (L2)2Ϫ and the pseudooctahedral coordination prefer-
the two O atoms from (LЈ)2Ϫ occupy the trans positions in ences of the CuII and NaI centers, and, also, the positive
the basal plane of the square pyramidal coordination poly- and the negative charges are exactly balanced. This perfect
hedron of CuII, which can be ascribed to the tendency for match gives extreme thermal stability to the novel coordi-
the six-membered chelate ring in [Cu4LЈ4] to span a larger nation polymer: no weight loss was observed for 3 until
distance, as compared to the corresponding five-membered about 328 °C. These subtle matching factors are delicate,
ring in complex 1. In [Cu4LЈ4], all the alkoxo groups act as and extremely sensitive to the structures of the ligands. As
µ3-bridges, with the phenoxo groups at the trans positions for H2L2, similar complexes with other divalent metals, na-
not involved in bridging. In contrast, the neighboring al- mely, the CoII complex [CoL2]·NaClO4·CH3OH (4) and the
koxo and phenoxo groups in complex 1 are involved in ZnII complex [ZnL2·NaClO4]·H2O (5) were also obtained;
more complicated bridging modes (vide supra), resulting in however, for H2L3, only the corresponding CoII complex
the larger nuclearity.
[CoL3NaClO4]·1.5H2O (7) was obtained. No NaClO4 is in-
Considering the distances between the O, N, and ClϪ cluded in the CuII and ZnII complexes of H2L3.
atoms, the water molecules, and the chlorides, form compli-
cated hydrogen-bond networks with the amino, phenoxo,
and alkoxo groups of the (L1)2Ϫ ligands. These multiple hy-
drogen bonds may contribute to the stability of the com-
Conclusions
plex, and thus the crystal structure can readily be deter-
Various novel coordination assemblies can be successfully
mined at room temperature. For the polynuclear CuII com- obtained by altering the ligands and metal atoms. For metal
plex of (L1)2Ϫ, the crystal structure cannot be obtained due atoms with octahedral coordination preferences, with in-
to its efflorescence during measurement.[8] In the ZnII com- creasing steric hindrance and the decreasing bridging ability
plex [ZnHL1Cl] (2), the alkoxy group is not deprotonated, of the ligands, the structures of the products vary from po-
even if an excess of NaOH is added, which can be ascribed lynuclear cluster and 1D heterometallic coordination poly-
to the weaker coordination of ZnII, as compared to CoII mer to weak axial monophenoxo-bridged binuclear moiet-
and CuII. The positive charge of ZnII is balanced by a chlo- ies. For the soft AgI atom, which prefers tetrahedral coordi-
ride, in addition to the deprotonated phenoxo group.
nation, H2L2 coordinates bidentately via the N atoms to
In contrast to H2L1, the tetradentate ligand H2L2 has an give a 1:2 complex. These results provide further insight
additional phenyl ring, and H2L3 has a further two methyl into the subtle structure-directing factors of metal com-
groups on the two phenyl rings Ϫ severe steric hindrance plexes, including the metal coordination preferences, the
4014
 2003 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
Eur. J. Inorg. Chem. 2003, 4010Ϫ4016

Novel Complexes of Ligands Containing Phenol and Alcohol Groups
FULL PAPER
[CoL2NaClO4]·CH3OH (4): Co(OAc)2·4H2O (100 mg, 0.40 mmol),
disposition of the bridging groups, the conformational flexi-
bility, the hydrogen bonds, and the steric effect of the li-
gands. This work may be valuable in our aim to design and
synthesize novel complexes; for example, coordination as-
semblies could arise by modifying the aliphatic chains or
the phenyl rings of the ligands or by adding further donor
groups into the phenyl rings.
H2L2 (117 mg, 0.40 mmol), aqueous NaOH (0.2 mL,
4 ,
0.8 mmol) and NaClO4 (49 mg, 0.40 mmol) were added success-
ively to methanol (50 mL). The resulting solution was boiled under
reflux for 4 h, and then concentrated in vacuo to give a yellowish
green powder that was collected and washed with diethyl ether and
dried (yield 153 mg, 79%). C17H22ClCoN2NaO7: calcd. C 42.21, H
4.58, N 5.79; found C 42.63, H 4.67, N 5.77. IR (KBr pellet, cmϪ1):
ν˜ ϭ 3424 br., 3226 m (NϪH), 2927 m, 1598 s, 1481 s, 1451 s, 1399
m, 1272 s (CϪO), 1116 s, 1106 s, 1085 s, 881 m, 759 s, 625 m, 594
w, 508 w.
Experimental Section
[ZnL2·NaClO4]·H2O (5): Complex 5 was prepared by a procedure
similar to that of 3, using Zn(ClO4)2·6H2O instead of
Cu(ClO4)2·6H2O (yield 173 mg, 91%). C16H20ClN2NaO7Zn: calcd.
C 40.36, H 4.23, N 5.88; found C 40.23, H 4.34, N 6.05. IR (KBr
pellet, cmϪ1): ν˜ ϭ 3440 br., 3254 m (NϪH), 2922 m, 1597 s, 1481
s, 1452 s, 1366 m, 1272 s (CϪO), 1110 s, 1039 s, 928 m, 877 m, 760
s, 733 m, 623 m, 591 m.
Physical Measurements: IR spectra were recorded with a Bruker
Vector-22 spectrometer (KBr Disc.). UV-Vis spectra were obtained
with a Shimadzu UV-Vis 2401 PC spectrophotometer. EPR meas-
urements were performed with a Bruker ER200D-SRC spec-
trometer at X-band (9.46 GHz). Microanalyses of C, H and N were
carried out with a GmbH VarioEL elemental analyzer. Magnetic
susceptibility data were collected with a Quantum Design Squid
magnetometer in the temperature range 5Ϫ300 K. The data were
corrected for the diamagnetism of the sample holder and for dia-
magnetic contributions with Pascal’s constants.
[CuL3]4·4H2O (6): The microcrystalline green solid complex 6 was
prepared by a procedure similar to that of 3, using H2L3 instead
of H2L2 (yield 128 mg, 84%). C72H96Cu4N8O12: calcd. C 56.90, H
6.37, N 7.37; found C 56.69, H 6.07, N 7.01. IR (KBr pellet, cmϪ1):
ν˜ ϭ 3443 br. (H2O), 3256 s (NϪH), 2919 m, 1642 w, 1488 vs, 1290
s, 1272 s (CϪO), 1254 s (CϪO), 1122 s, 1093 s, 1055 s, 998 w, 957
w, 863 m, 818 s, 796 s, 635 m, 500 m.
Caution! Perchlorate salts of metal complexes with organic ligands
are potentially explosive. Only a small amount of the material should
be used and it should be handled with extreme care.
Single crystals of 1, 3, and 6 were grown by slow evaporation of
their methanol solutions.
5-Methylsalicylaldehyde was prepared by the reaction of p-cresol
and CHCl3 in aqueous ethanol according to the ReimerϪTiemann
procedure. H2L1·HCl·1.5H2O was synthesized by the method re-
ported earlier;[8] H2L2 was prepared by a similar method., and
H2L3 was prepared in analogues fashion starting from 5-methyl-
salicylaldehyde and ethylenediamine.
CoL3NaClO4·1.5H2O (7): Complex 7 is a yellowish green powder
that was prepared by a procedure similar to that of 4, using H2L3
instead of H2L2 (yield 158 mg, 78%). C36H50Cl2Co2N4Na2O15:
calcd. C 42.66, H 5.53, N 4.97; found C 42.69, H 5.21, N 5.36. IR
(KBr pellet, cmϪ1): ν˜ ϭ 3442 br., 3226 m (NϪH), 2919 m, 1612 s,
1487 s, 1272 s (CϪO), 1118 s, 1108 s, 1082 s, 1046 s, 969 w, 927 w,
798 m, 625 m, 517 m.
[Co6L16(OH)(H2O)3]Cl2·10H2O (1): Co(OAc)2·4H2O (100 mg,
0.40 mmol), H2L1·HCl·1.5H2O (89 mg, 0.40 mmol), aqueous
NaOH (0.3 mL, 4 , 1.2 mmol), and a few drops of H2O2 were
added successively to methanol (100 mL). The resulting solution
was then boiled under reflux for 3 h, and concentrated in vacuo.
The so-obtained microcrystalline brown solid was collected and
washed with diethyl ether and dried (yield 97 mg, 87%).
C54H93Cl2Co6N6O26: calcd. C 38.91, H 5.62, N 5.04; found C
38.69, H 5.63, N 4.89. IR (KBr pellet, cmϪ1): ν˜ 3386 br. (H2O),
3190 s (NϪH), 1596 s, 1567 m, 1483 s, 1448 s, 1304 m, 1284 s
(CϪO), 1270 vs (CϪO), 882 m, 759 s, 685 s, 630 m, 602 w, 535 w.
[ZnL3]·2H2O (8): Complex 8 was prepared by a procedure similar
to that of 7, using H2L3 instead of H2L2 (yield 128 mg, 80%).
C18H26N2O4Zn: calcd. C 54.08, H 6.55, N 7.01; found C 54.24, H
6.24, N 7.05. IR (KBr pellet, cmϪ1): ν˜ ϭ 3408 br., 3253 m (NϪH),
2916 m, 2859 m, 1611 s, 1488 s, 1269 s (CϪO), 1127 m, 1047 m,
825 s, 790 s, 756 m, 726 w, 531 w, 492 m.
[Ag(H2L2)(HL2)] (9): A solution of AgNO3 (68 mg, 0.40 mmol) in
H2O (5 mL) was added to a solution of H2L2 (117 mg, 0.40 mmol)
in methanol (5 mL). The resultant precipitate was redissolved by
the addition of concentrated ammoniacal solution (5 mL). The re-
sulting solution was then filtered and left in a P2O5 desiccator in a
dark place to slowly evaporate. Single crystals were obtained after
several days in 35% yield (91 mg). C32H39AgN4O4: calcd. C 58.99,
H 6.03, N 8.60; found C 58.80, H 5.78, N 8.31. IR (KBr pellet,
cmϪ1): ν˜ ϭ 3300 m (NϪH), 2922 m, 2857 m, 1595 s, 1454 s, 1385
m, 1329 w, 1251 s (CϪO), 1186 m, 876 m, 829 m, 752 s, 504 m.
[ZnHL1Cl] (2):
A
solution of Zn(ClO4)2·6H2O (149 mg,
0.40 mmol), H2L1·HCl·1.5H2O (89 mg, 0.40 mmol), and aqueous
NaOH (0.2 mL, 4 , 0.8 mmol) was boiled under reflux for 4 h,
and then concentrated in vacuo. The resulting colorless solid was
collected and washed with diethyl ether and dried (yield 91 mg,
85%). C9H12ClNO2Zn: calcd. C 40.48, H 4.53, N 5.25; found C
40.59, H, 4.75, N 5.06. IR (KBr pellet, cmϪ1): ν˜ ϭ 3260 m (NϪH),
2922 w, 2859 w, 1597 s, 1569 m, 1483 s, 1453 s, 1277 s (CϪO), 1086
s, 1021 s, 874 m, 760 s, 623 m, 592 w, 528 w.
X-ray Crystallography: All measurements were made with a Rigaku
[CuNaL2(ClO4)]ϱ (3): The microcrystalline brown solid complex 3
RAXIS-IV image plate area detector with Mo-Kα radiation (λ ϭ
˚
was prepared by a procedure similar to that of 2, starting from 0.71073 A). The structures were solved by direct methods and ex-
Cu(ClO4)2·6H2O (0.142 g, 0.40 mmol), H2L2 (117 mg, 0.40 mmol),
and NaOH (0.2 mL, , 0.8 mmol) (yield 170 mg, 93%). refined anisotropically. Hydrogen atoms were included but not re-
panded using Fourier techniques. The non-hydrogen atoms were
4
C16H18ClCuN2NaO6: calcd. C 42.12, H 3.98, N 6.14; found C
fined. The final cycle of full-matrix least-squares refinement was
42.04, H 4.01, N 5.88. IR (KBr pellet, cmϪ1): ν˜ ϭ 3263 s (NϪH), based on observed reflections [I Ͼ 2.00σ(I)] and variable param-
3059 w, 2884 w, 1597 w, 1566 w, 1483 s, 1451 s, 1290 s, 1270 s eters. All calculations were performed by using the SHELX-97
(CϪO), 1116 s, 1108 s, 1088 s, 1055 m, 1038 m, 992 m, 958 w, 926
w, 883 m, 858 w, 755 s, 729 m, 626 s, 596 w, 570 m, 530 w, 408 w.
software package.[18] A summary of the crystal data is presented
in Table 5.
Eur. J. Inorg. Chem. 2003, 4010Ϫ4016
www.eurjic.org
 2003 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
4015

Y. Xie, Q. Liu, H. Jiang, J. Ni
FULL PAPER
Table 5. Details of X-ray structure determinations
Complexes
1
3
6
9
Empirical formula
Formula mass
Crystal System
Space group
T (K)
C54H93Cl2Co6N6O26
1666.85
C16H18ClCuN2NaO6
456.30
C72H96Cu4N8O12
1519.73
monoclinic
P21/c
C32H39AgN4O4
651.54
monoclinic
P21/c
triclinic
triclinic
¯
¯
P1
P1
293(2)
291(2)
7.456(2)
11.283(2)
11.326(2)
78.15(3)
89.07(3)
88.32(3)°
932.0(3)
2
291(2)
291(2)
˚
a (A)
15.363(3)
16.161(3)
14.981(3)
91.54(3)
106.17(3)
96.85(3)°
3539.7(12)
2
20.524(4)
12.765(3)
28.181(6)
90.00
98.64°
90.00
7299(3)
4
1.383
11.395(2)
13.044(3)
21.277(4)
90.00
95.00(3)
90.00
3150.5(11)
4
1.374
˚
b (A)
˚
c (A)
α (°)
β (°)
γ (°)
3
˚
V (A )
Z
Dcalcd. (Mg/m3)
1.541
1.528
1.626
1.374
µ (mmϪ1
)
1.214
0.681
No. of reflns. [I Ͼ 2σ(I)]
Final R1 [I Ͼ 2σ(I)]
wR2 (all data)
7703
1757
7318
4585
0.0424
0.0767
1.031
0.0842
0.2550
1.064
0.0683
0.1703
1.080
0.0736
0.1098
1.032
Goodness of fit
[7b]
3020Ϫ3028.
J. A. Cappuccio, I. Ayala, G. I. Elliott, I.
CCDC-183121 to -183124 contain the supplementary crystallo-
graphic data for this paper. These data can be obtained free of
charge at www.ccdc.cam.ac. uk/cont/retrieving.html [or from the
Cambridge Crystallographic Data center, 12 Union Road, Cam-
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 2003 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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Eur. J. Inorg. Chem. 2003, 4010Ϫ4016