Syntheses, structures and magnetic properties of mono- and di-manganese inclusion compounds

Article abstract of DOI:10.1016/S0020-1693(01)00489-3

Mono- and di-manganese inclusion compounds 1 and 2 are reported. Two mono-manganese molecules Mn(bpy)₂(NO₃)₂ (bpy = 2,2′-bipyridine) and [Mn(bpy)₂(NO₃)(H₂O)]·NO₃ coexist in the mole ratio of 1:1 in the structure of 1, while two di-manganese molecules [Mn₂O(bpy)₂(phtha)₂(H₂O) ₂]·(NO₃)₂ (phtha = phthalate) and [Mn₂O(bpy)₂(phtha)₂(NO₃)(H ₂O)]·NO₃ in the structure of 2. Refluxing Mn(NO₃)₂/bpy/phthalic acid reaction mixtures in CH₃CN leads to the isolation of 1, further concentration of the reaction solution in raising temperature results in 2. The Mn₁ and Mn₂ units in the inclusion compounds 1 and 2 are similar to other reported Mn₁ and Mn₂ analogs, respectively. The Jahn-Teller distortion was observed to give rise to the elongation along the O_terminal-Mn-O_carboxyl axes for all the four Mn(III) sites in 2, leading to unexpected longer Mn(III)-O_aqua than Mn(II)-O_aqua in 1. Extensive hydrogen bonding interactions among H₂O, NO₃^- and COOH were observed in the two inclusion compounds. Cyclic voltammetry of 2 in DMF displays two quasi-reversible redox couples at +0.10/+0.22 and -0.43/-0.36 V assigned to the Mn(III)Mn(IV)/2Mn(III) and 2Mn(III)/Mn(III)Mn(II), respectively. Variable temperature magnetic susceptibilities of 1 and 2 were measured. The data were fit to a model including axial zero-field splitting term and a good fit was found with D = 1.77 cm^-1, g = 1.98 and F = 1.48 × 10^-5 for 1. For 2, the least-squares fitting of the experimental data led to J = 2.37 cm^-1, g = 2.02 and D = 0.75 cm^-1 with R = 1.45 × 10^-3.

Full text of DOI:10.1016/S0020-1693(01)00489-3

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Inorganica Chimica Acta 320 (2001) 159–166
Syntheses, structures and magnetic properties of mono- and
di-manganese inclusion compounds
Changneng Chen a, Hongping Zhu a, Deguang Huang a, Tingbin Wen a, Qiutian Liu a,*,
Daizheng Liao b, Jianzhong Cui b
a State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou,
Fujian 350002, China
b Department of Chemistry, Nankai Uni6ersity, Tianjin 300071, China
Received 24 January 2001; accepted 17 May 2001
Abstract
Mono- and di-manganese inclusion compounds 1 and 2 are reported. Two mono-manganese molecules Mn(bpy)2(NO3)2
(bpy=2,2%-bipyridine) and [Mn(bpy)2(NO3)(H2O)]·NO3 coexist in the mole ratio of 1:1 in the structure of 1, while two
di-manganese molecules [Mn2O(bpy)2(phtha)2(H2O)2]·(NO3)2 (phtha=phthalate) and [Mn2O(bpy)2(phtha)2(NO3)(H2O)]·NO3 in
the structure of 2. Refluxing Mn(NO3)2/bpy/phthalic acid reaction mixtures in CH3CN leads to the isolation of 1, further
concentration of the reaction solution in raising temperature results in 2. The Mn1 and Mn2 units in the inclusion compounds 1
and 2 are similar to other reported Mn1 and Mn2 analogs, respectively. The Jahn–Teller distortion was observed to give rise to
the elongation along the OterminalꢀMnꢀOcarboxyl axes for all the four Mn(III) sites in 2, leading to unexpected longer Mn(III)ꢀOaqua
than Mn(II)ꢀOaqua in 1. Extensive hydrogen bonding interactions among H2O, NO3− and COOH were observed in the two
inclusion compounds. Cyclic voltammetry of 2 in DMF displays two quasi-reversible redox couples at +0.10/+0.22 and
−0.43/−0.36 V assigned to the Mn(III)Mn(IV)/2Mn(III) and 2Mn(III)/Mn(III)Mn(II), respectively. Variable temperature
magnetic susceptibilities of 1 and 2 were measured. The data were fit to a model including axial zero-field splitting term and a
good fit was found with D=1.77 cm−1, g=1.98 and F=1.48×10−5 for 1. For 2, the least-squares fitting of the experimental
data led to J=2.37 cm−1, g=2.02 and D=0.75 cm−1 with R=1.45×10−3. © 2001 Elsevier Science B.V. All rights reserved.
Keywords: Crystal structures; Magnetic properties; Manganese complexes; Phthalate complexes; Inclusion complexes
1. Introduction
bidentate and tridentate N-containing ligands such as
bipyridine and carboxylic acid gives rise to the di-man-
ganese complexes containing the m-oxo-bis-m-carboxy-
lato unit [3,4]. Up to now acetate and benzoate have
always been reported as the bis-m-carboxylato unit,
while the use of dicarboxylic acid in the reaction has
rarely been studied for preparing poly-manganese com-
pound [5]. We are interested in the formation of the
di-manganese complexes in the presence of dicarboxylic
acid, since this assembly may have potential interest for
the further aggregate of the manganese cluster, leading
to a polynuclear Mn cluster. Here we report the synthe-
ses of mono- and di-manganese complexes and their
structural characterization. Their magnetic properties
are also discussed.
During the past two decades, modeling the structure,
the spectroscopic properties and the reactivity of man-
ganese cluster in photosystem II are of major interest to
inorganic chemists. A great deal of Mn complexes with
Mn(II, III, IV) centers and O,N-donor atoms have been
synthesized as a model of the water oxidation center [1].
Di-manganese complexes with m-oxo-bis-m-carboxylato
unit have attracted more attention since the unit was
proposed as the active site in the ribonucleotide reduc-
tase [2]. In the previous known researches, the use of
* Corresponding author. Fax: +86-591-371-4946.
E-mail address: lqt@ms.fjirsm.ac.cn (Q. Liu).
0020-1693/01/$ - see front matter © 2001 Elsevier Science B.V. All rights reserved.
PII: S0020-1693(01)00489-3

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C. Chen et al. / Inorganica Chimica Acta 320 (2001) 159–166
2. Experimental
yield based on phthalic acid. Anal. Found: C, 47.59; H,
3.17; Mn, 11.16; N, 9.39. Calc. for C72H58Mn4N12O33:
C, 47.02; H, 3.18; Mn, 11.95; N, 9.14%. IR (KBr,
cm−1): 3400 (m, br), 3112 (w), 1737 (s), 1610 (s), 1589
(m), 1447 (m), 1384 (s), 1307 (m), 1249 (w), 1173 (w),
1075 (w), 1034 (w), 826 (w), 771 (m), 728 (m), 652 (w),
477 (w), 334 (w).
All manipulations were performed under aerobic
conditions with materials as received.
2.1. Synthesis
2.1.1. [Mn2(bpy)4(NO3)3(H2O)]NO3 (1) and
[Mn4(bpy)4(o-HOOCC6H4COO)4(v-O)2(H2O)3(NO3)]-
2.2. X-ray crystallography and structure solution
(NO3)3 (2)
Solid 2,2%-bipyridine (0.50 g, 3.20 mmol),
Mn(NO)3·4H2O (0.64 g, 2.55 mmol), and phthalic acid
(0.41 g, 2.47 mmol) were mixed in 50 ml of acetonitrile
and stirred for 3 h at room temperature (r.t.). Then the
solution was continuously stirred and refluxed for 2 h.
After filtration to remove the light yellow precipitate,
the filtrate was allowed to stand for several days to
deposit bright yellow crystals which were collected and
dried in vacuo, yielding 0.45 g (yield 56% based on bpy)
of 1. Anal. Found: C, 48.19; H, 3.39; Mn, 10.61; N,
16.89. Calc. for C40H34Mn2N12O13: C, 48.01; H, 3.42;
Mn, 10.98; N, 16.80%. IR (KBr, cm−1): 3441 (m, br),
1594 (s), 1472 (m), 1437 (s), 1384(s), 1313 (w), 1247 (w),
1173 (w), 1150 (w), 1097 (w), 1058 (w), 1013 (m), 820
(w), 773 (s), 737 (m), 651 (w), 625 (w).
In the preceding procedure, the filtrate of reaction
mixture containing 1 was concentrated at rising temper-
ature to remove 30 ml of the solvent, accompanying the
color change from light yellow to dark brown. The
concentrated solution was allowed to stand at r.t. for
several days to deposit dark brown crystals, which were
collected and dried in vacuo, affording 2 with 14.5%
Crystalline samples were selected from the reaction
solutions for 1 and 2, and were coated with epoxy resin
and mounted. Data were collected on AFC 5R Rigaku
diffractometer and Siemens Smart CCD for 1 and 2,
respectively. The data collections were performed using
ꢀ–2q scan mode with the maximum q of 26° for 1, and
ꢀ mode in the range of 2.02BqB25.03° for 2. For 1
9232 unique reflections were obtained for which
Lorentz polarization correction was applied. For 2 8594
unique reflections obtained were reduced by Siemens
Saint and corrected by SADABS (0.7594–1.0000). The
crystallographic data of the two compounds are listed
in Table 1.
The structure was solved by a combination of direct
methods and Fourier techniques for each compound
and the Mn atoms were located from initial E-maps.
The positions of the remaining non-hydrogen atoms
were obtained from subsequent iterations of least-
squares refinement and difference Fourier maps phased
on the already located atoms. Hydrogen atoms were
geometrically located and added to the structure factor
calculations but their positions were not refined. Com-
pound 2 contains both almost the same dinuclear man-
(
ganese cluster units in cell which seems to have P1
feature. However, the refinement with a symmetrical
center leaded to a vague description of a tetranuclear
Mn cluster. Consequently, space group P1 was selected
and used to give two Mn2 clusters coexisting in an
inclusion compound. The structures of 1 and 2 were
refined by full-matrix least-squares technique using an-
isotropic thermal parameters for all the non-hydrogen
atoms except for the oxygen atom (O45) in the solvate
H2O of 2. One of the oxygen atoms in external NO3−
group which is not coordinated to the Mn atom in 2
was found to be disordered at two positions (O31 and
O31%) with the occupancies of 0.2 and 0.8, respectively.
For 1 the final refinement included 604 variable
parameters for 3089 [I\1.0|(I)] reflections, and con-
verged to R=0.0585 and Rw=0.0751. For 2, 1139
variable parameters and 6041 [I\2.0|(I)] reflections,
of which one reflection (hkl 0, 0, 1) with too high
D(F2)/esd value was omitted, were refined to give final
R=0.0543 and Rw=0.1407. The highest and the mini-
Table 1
Crystallographic data for compounds 1 and 2
Empirical formula
Formula weight
Temperature (°C)
u(Mo Ka)
Space group
Unit cell dimensions
C40H34Mn2N12O13
1000.67
20
0.71069
Pbca (no. 61)
C72H68Mn4N12O38
1929.14
20
0.71073
P1 (no. 1)
,
a (A)
14.39(1)
17.12(1)
34.70(1)
10.007(2)
10.284(2)
20.283(4)
78.98(3)
80.95(3)
85.67(3)
2021.1(7)
1
1.585
0.713
0.0543
0.1407
,
b (A)
,
c (A)
h (°)
i (°)
k (°)
3
,
V (A )
Z
8545(18)
8
1.56
0.64
0.0585
0.0751
zcalc (g cm−3
)
v (mm−1
)
a
R
b
Rw
1, w=1/[S2(F)+(0.030F)2+1.0]−F; 2, w=1/[S2(Fo2)+(0.1000P)2+
0.0000P], where P=(Fo2+2Fc2)/3.
mum residual peaks in the final difference Fourier map
−3
a R=ꢀꢁꢁFoꢁ−ꢁFcꢁꢁ/ꢀꢁFoꢁ.
,
had a height of 0.37 and −0.09 e A
for 1, and 0.638
−3
b Rw=[ꢀw(ꢁFoꢁ−ꢁFcꢁ)2/ꢀwFo2]1/2
.
and −0.513 e A
for 2. All calculations were per-
,

C. Chen et al. / Inorganica Chimica Acta 320 (2001) 159–166
161
Fig. 1. ORTEP representation of the two components in compound 1 at the 30% probability level.
formed by using MULTAN-83 (
and SHELXTL 93 [7] for 2.
M
olEN) program [6] for 1
[Mn2(m - O)(bpy)2(o - HOOCC6H4COO)2(H2O)(NO3)]-
(NO3) in a molar ratio of 1:1. Recently, linking simple
Mn species by poly-functional ligands to produce
higher nuclearity of manganese complex has attracted
more attention [9,10]. Compound 1 can be seen as a
building block to construct the di-manganese aggregate
2. It is noted that the two mono-manganese compo-
nents wrapped up in 1 are available to aggregate with
each other to produce the di-manganese aggregate with
terminal ligands H2O or NO3−. On heating and concen-
trating the reaction solution, a peripheral basic bpy
ligand would be abstracted by phthalic acid from 1 to
give an intermediate fragment, which was oxidized by
air and linked together to give the di-Mn(III) species.
Similar di-Mn(III) complexes have been reported,
which were formed in an assembly system in the pres-
ence of an oxidizer, such as MnO−4 [3b]. A condensa-
tion mechanism has been suggested by Rajasekharan
[3c] to explain the formation of [Mn2(m-O)(bpy)2-
(OAc)2(H2O)(NO3)](ClO4), in which m-O comes from
the dehydration of hydroxyl groups contained in the
MnꢀOH moieties. It may be reasonable to consider that
the bridging m-oxo anion results from the dehydration
of the Mn(III)ꢀOH group, which comes from the oxi-
dation of the Mn(II) site and then the deprotonation of
the aqua ligating to the oxidized Mn site.
-
2.3. Other physical measurements
The IR spectra were recorded on a Bio-Rad FTS-40
Model spectrophotometer. The variable temperature
susceptibilities were measured on a Model CF-1 super-
conducting extraction sample magnetometer with the
crystalline sample kept in a capsule at 5–300 K. Dia-
magnetic corrections of −509×10−6 and −466.5×
10−6 emu mol−1 were used for compounds 1 and 2,
respectively. Electrochemical measurement was per-
formed in the cyclic voltammetric mode on a CV-1B
cyclic voltammeter in DMF with an SCE reference
electrode, graphite working electrode, and Pt auxiliary
electrode. The supporting electrolyte was Et4NBF4.
3. Results and discussion
3.1. Synthesis
Some mononuclear Mn complexes [8] with bpy lig-
and have been synthesized by reaction of bpy with
simple inorganic Mn salt and have been structurally
characterized. Compound 1 is an inclusion compound
containing [Mn(bpy)2(NO3)(H2O)]NO3 and Mn(bpy)2-
(NO3)2 molecules in a molar ratio of 1:1. Though the
former has been reported [8a], compound 1 is still an
interesting example among the mononuclear Mn com-
plexes for structural and chemical studies. Especially,
the further reaction of 1 with phthalic acid in the
reaction solution caused condensation of the mononu-
clear complex and produced di-manganese compound
2. It is interesting that 2 is also an inclusion compound
composed of two di-manganese molecules [Mn2(m-
3.2. Structure
The structure of the inclusion compound 1 is repre-
sented in Fig. 1. Selected bond distances and angles are
listed in Table 2. The structure consists of two mononu-
clear Mn molecules Mn(bpy)2(NO3)2 and [Mn(bpy)2-
(NO3)(H2O)]NO3. The structure of the latter has been
reported by Chen [8a], and the structure of the former
is also normal for the mononuclear Mn complexes
containing the [Mn(bpy)2]2+ core. The ligands form
O)(bpy)2(o-HOOCC6H4COO)2(H2O)2](NO3)2
and

162
C. Chen et al. / Inorganica Chimica Acta 320 (2001) 159–166
[Mn(bpy)2(NO3)(H2O)]NO3 than that in Mn(bpy)2-
(NO3)2 (87.0°). This seems to be in contradiction with
the larger stereo effect of NO3− than that of H2O.
However, strong hydrogen bonding interactions be-
a distorted octahedral coordination sphere about the
Mn atom with the bpy bite angle NꢀMnꢀN ranging
from 71.1 to 72.4° and the MnꢀN distance ranging
,
from 2.248 to 2.366 A. These values are close to those
tween ligated H2O and discrete NO3− (O0···O10, 2.59
found in other mononuclear Mn(II) bpy complexes [8].
It is noted that in the inclusion compound the MnꢀN
bond lengths trans to Onitrate, Nbpy and Oaqua average
−
,
A), and between the aqua and ligated NO3 belonging
,
to the other molecule (O0···O5, 2.76 A) were observed
as shown in Fig. 2. These interactions enable the
OaquaꢀMnꢀOnitrate angle in [Mn(bpy)2(NO3)(H2O)]+ to
become larger.
,
2.316(30), 2.269(10) and 2.250(6) A, respectively, show-
ing stronger trans-effect of the NO3− group than the
other two. A larger OꢀMnꢀO angle (98.4°) is found in
Fig. 3 illustrates the structure of the other inclusion
compound 2. It consists of two di-manganese cluster
Table 2
cations,
[Mn2(m-O)(bpy)2(phtha)2(H2O)2]2+
and
,
Selected bond lengths (A) and bond angles (°) for compound 1
[Mn2(m-O)(bpy)2(phtha)2(H2O)(NO3)]+, three nitrate
anions as well as five solvate H2O molecules. Selected
bond distances and angles are listed in Table 3. It is
necessary to point out that the structural difference of
the two components constructing the inclusion com-
pound is displayed only in their terminal ligands. A
series of di-manganese compounds have been reported
some of which were suspected to be a mixture [3b,c] of
two Mn2 clusters (H2O, NO3− or OH− ligation) with
indefinite proportion. This implies that the terminal
ligands in these compounds are labile and easy to
exchange with each other, leading to the formation of
the mixture that is difficult to purify, or in the rare
situation, leading to the formation of di-molecule inclu-
sion compounds, such as 1 and 2. Both di-manganese
ions in 2 possess similar structural parameters as shown
in Table 3, except for the identity of the terminal
ligands (NO3− and H2O). In fact, all the atoms of the
two Mn2 components are related by a symmetrical
center located in the middle of the line joining two
Mn(III) sites (Mn2···Mn4 and Mn1···Mn3), except the
atoms in the terminal ligands. In comparison to the
other m-oxo bis-m-carboxylato di-manganese com-
pounds, our di-manganese complexes exhibit a close
similarity in the structural parameters of the core
Mn1ꢀO0
Mn1ꢀO1
Mn1ꢀN11
Mn1ꢀN12
Mn1ꢀN21
Mn1ꢀN22
2.133(6)
2.275(6)
2.248(6)
2.250(6)
2.319(6)
2.289(6)
Mn2ꢀO4
Mn2ꢀO8
Mn2ꢀN31
Mn2ꢀN32
Mn2ꢀN41
Mn2ꢀN42
2.236(6)
2.359(8)
2.262(6)
2.286(7)
2.366(7)
2.254(6)
O0ꢀMn1ꢀO1
98.4(2)
94.8(2)
167.1(2)
92.3(2)
92.4(2)
114.1(2)
86.2(2)
153.3(2)
83.9(2)
72.4(2)
71.2(2)
159.3(2)
88.7(2)
89.1(2)
100.1(2)
O4ꢀMn2ꢀO8
87.0(2)
154.8(2)
86.4(2)
80.1(3)
102.7(2)
98.7(3)
77.4(3)
160.9(2)
125.8(3)
71.1(2)
71.2(2)
155.0(2)
87.8(2)
87.6(2)
93.9(2)
O0ꢀMn1ꢀN11
O0ꢀMn1ꢀN12
O0ꢀMn1ꢀN21
O0ꢀMn1ꢀN22
O1ꢀMn1ꢀN11
O1ꢀMn1ꢀN12
O1ꢀMn1ꢀN21
O1ꢀMn1ꢀN22
N11ꢀMn1ꢀN12
N21ꢀMn1ꢀN22
N11ꢀMn1ꢀN22
N12ꢀMn1ꢀN21
N11ꢀMn1ꢀN21
N12ꢀMn1ꢀN22
O4ꢀMn2ꢀN31
O4ꢀMn2ꢀN32
O4ꢀMn2ꢀN41
O4ꢀMn2ꢀN42
O8ꢀMn2ꢀN31
O8ꢀMn2ꢀN32
O8ꢀMn2ꢀN41
O8ꢀMn2ꢀN42
N31ꢀMn2ꢀN32
N41ꢀMn2ꢀN42
N32ꢀMn2ꢀN42
N32ꢀMn2ꢀN41
N31ꢀMn2ꢀN41
N31ꢀMn2ꢀN42
Mn(III)2(m-O)(m-RCOO)2, such as Mn···Mn, MnꢀOoxo
,
MnꢀOaqua, MnꢀOcarboxyl, and MnꢀOꢀMn values (Table
4), exhibiting that the terminal ligands (NO3−, H2O,
Cl−, or N−3 ) ligating to the Mn site have no serious
effect on their core structures. The evidence for a
Jahn–Teller elongation of Mn(III) with high spin d4
was observed. The MnꢀOcarboxyl distances are divided
,
into two sets differing by 0.17–0.2 A, and the
,
MnꢀOaqua distances (2.182, 2.191, 2.256 A) for the
Mn3+ oxidation state are unexpectedly longer than
,
that (2.133 A) in 1 and other Mn(II) complexes [8a,c].
It is reasonable to consider that the Jahn–Teller distor-
tion gives rise to the elongation along the
OterminalꢀMnꢀOcarboxyl axes for all the Mn(III) sites in 2.
Interestingly, in compound 2 the longest MnꢀOaqua
,
distance is Mn2ꢀO24 of 2.256 A, this even longer
Fig. 2. Packing diagram of unit cell of 1. Hydrogen bonds are
indicated by dotted lines. The peripheral hydrogen bonds have been
omitted.
distance is probably due to the hydrogen bonding
−
,
(O22···O24, 2.865 A) with the NO3 group coordinated

C. Chen et al. / Inorganica Chimica Acta 320 (2001) 159–166
163
Fig. 3. Structure of compound 2 showing two Mn2 units, anions and solvate H2O molecules. Hydrogen bonding interactions between the
components are also shown by dotted lines.
Table 3
,
Selected bond lengths (A) and bond angles (°) for compound 2
[Mn2O(m-phth)2(bpy)2(H2O)2]2+
[Mn2O(m-phth)2(bpy)2(H2O)(NO3)]+
Mn1ꢀMn2
Mn1ꢀO1
Mn1ꢀO5
Mn1ꢀN1
Mn1ꢀN2
Mn1ꢀO3
Mn1ꢀO2
3.148(3)
1.769(9)
Mn3ꢀMn4
Mn3ꢀO11
Mn3ꢀO15
Mn3ꢀN6
Mn3ꢀN5
Mn3ꢀO13
Mn3ꢀO23
3.155(3)
Mn2ꢀO1
Mn2ꢀO4
Mn2ꢀN3
Mn2ꢀN4
Mn2ꢀO6
Mn2ꢀO24
1.776(11)
2.003(10)
2.087(12)
2.105(13)
2.172(11)
2.256(12)
1.773(10)
1.938(11)
2.040(13)
2.047(12)
2.125(10)
2.311(10)
Mn4ꢀO11
Mn4ꢀO14
Mn4ꢀN8
Mn4ꢀN7
Mn4ꢀO16
Mn4ꢀO12
1.839(10)
1.927(11)
2.049(13)
2.087(13)
2.135(11)
2.191(11)
1.999(10)
2.046(13)
2.070(12)
2.171(11)
2.182(11)
O1ꢀMn1ꢀO5
O1ꢀMn1ꢀN1
O5ꢀMn1ꢀN1
O1ꢀMn1ꢀN2
O5ꢀMn1ꢀN2
N1ꢀMn1ꢀN2
O1ꢀMn1ꢀO3
O5ꢀMn1ꢀO3
N1ꢀMn1ꢀO3
N2ꢀMn1ꢀO3
O1ꢀMn1ꢀO2
O5ꢀMn1ꢀO2
N1ꢀMn1ꢀO2
N2ꢀMn1ꢀO2
O3ꢀMn1ꢀO2
Mn1ꢀO1ꢀMn2
C51ꢀO3ꢀMn1
C61ꢀO5ꢀMn1
C5ꢀN1ꢀMn1
C1ꢀN1ꢀMn1
C6ꢀN2ꢀMn1
C10ꢀN2ꢀMn1
98.4(5)
93.5(5)
168.1(5)
170.4(5)
90.6(5)
77.6(5)
91.4(4)
91.3(5)
89.1(5)
85.1(4)
96.8(5)
87.1(4)
90.8(5)
O1ꢀMn2ꢀO4
O1ꢀMn2ꢀN3
O4ꢀMn2ꢀN3
O1ꢀMn2ꢀN4
O4ꢀMn2ꢀN4
N3ꢀMn2ꢀN4
O1ꢀMn2ꢀO6
O4ꢀMn2ꢀO6
N3ꢀMn2ꢀO6
N4ꢀMn2ꢀO6
O1ꢀMn2ꢀO24
O4ꢀMn2ꢀO24
N3ꢀMn2ꢀO24
N4ꢀMn2ꢀO24
O6ꢀMn2ꢀO24
97.5(4)
91.4(5)
170.8(5)
168.2(5)
94.2(5)
76.9(5)
96.8(4)
89.5(4)
92.1(4)
84.3(4)
94.7(5)
84.2(4)
92.6(4)
85.5(5)
167.5(5)
O11ꢀMn3ꢀO15
O11ꢀMn3ꢀN6
O15ꢀMn3ꢀN6
O11ꢀMn3ꢀN5
O15ꢀMn3ꢀN5
N6ꢀMn3ꢀN5
99.3(5)
167.5(5)
93.1(5)
89.2(5)
171.4(5)
78.3(5)
99.2(5)
87.3(5)
82.4(5)
91.7(5)
92.2(4)
89.0(4)
86.8(4)
90.3(4)
168.4(4)
126.6(10)
130.4(10)
121.9(8)
117.6(11)
122.5(11)
125.5(9)
116.7(10)
O11ꢀMn4ꢀO14
O11ꢀMn4ꢀN8
O14ꢀMn4ꢀN8
O11ꢀMn4ꢀN7
O14ꢀMn4ꢀN7
N8ꢀMn4ꢀN7
100.9(5)
170.3(5)
88.8(5)
91.4(5)
167.5(5)
78.9(5)
91.7(4)
90.2(5)
87.5(5)
87.3(5)
93.0(4)
91.0(5)
87.5(5)
90.5(5)
174.8(5)
121.8(5)
128.5(10)
132.4(10)
124.4(10)
115.3(9)
126.9(11)
116.7(11)
O11ꢀMn3ꢀO13
O15ꢀMn3ꢀO13
N6ꢀMn3ꢀO13
N5ꢀMn3ꢀO13
O11ꢀMn3ꢀO23
O15ꢀMn3ꢀO23
N6ꢀMn3ꢀO23
N5ꢀMn3ꢀO23
O13ꢀMn3ꢀO23
C71ꢀO13ꢀMn3
C81ꢀO15ꢀMn3
N9ꢀO23ꢀMn3
C35ꢀN5ꢀMn3
C31ꢀN5ꢀMn3
C40ꢀN6ꢀMn3
C36ꢀN6ꢀMn3
O11ꢀMn4ꢀO16
O14ꢀMn4ꢀO16
N8ꢀMn4ꢀO16
N7ꢀMn4ꢀO16
O11ꢀMn4ꢀO12
O14ꢀMn4ꢀO12
N8ꢀMn4ꢀO12
N7ꢀMn4ꢀO12
O16ꢀMn4ꢀO12
Mn3ꢀO11ꢀMn4
C71ꢀO14ꢀMn4
C81ꢀO16ꢀMn4
C41ꢀN7ꢀMn4
C45ꢀN7ꢀMn4
C50ꢀN8ꢀMn4
C46ꢀN8ꢀMn4
87.0(5)
171.9(4)
125.2(6)
130.4(9)
131.8(10)
116.9(11)
123.9(11)
115.8(10)
122.7(11)
C51ꢀO4ꢀMn2
C61ꢀO6ꢀMn2
C11ꢀN3ꢀMn2
C15ꢀN3ꢀMn2
C16ꢀN4ꢀMn2
C20ꢀN4ꢀMn2
125.4(9)
131.0(11)
125.7(11)
116.0(10)
115.9(11)
123.4(11)
to Mn3. The presence of the nitrate and carboxyl
groups and the presence of coordinate and solvate H2O
molecules make extensive hydrogen bonding interac-
tions in the lattice of the inclusion compound as shown
in Fig. 3. All the hydrogen bonding interactions are
listed in Table 5. The importance of the hydrogen
bonding interactions for the formation of the inclusion
compounds can also not be ignored. These hydrogen
bonds make the two components (Mn2 or Mn1) insepa-
rably combine with each other to become an inclusion
compound. For 1 O0···O5 links the two Mn1 compo-
nents, while O22···O24 links the two Mn2 components
in 2. The hydrogen bonding interactions including O45
must be mentioned which occur between two

164
C. Chen et al. / Inorganica Chimica Acta 320 (2001) 159–166
Table 4
Comparison of the structural data for complexes containing Mn2(m-O)(bpy)2bis-(m-carboxylato) moiety
Complex
MnꢀMn
3.148(3)
3.155(3)
3.141(1)
3.152(2)
MnꢀN MnꢀO (oxo)
MnꢀO (aqua)
2.219
MnꢀO (carboxyl)
MnꢀOoxoꢀMn Ref.
[Mn2O(m-phth)2(bpy)2(H2O)2]2+
[Mn2O(m-phth)2(bpy)2(H2O)(NO3)]+
Mn2O(m-PhCOO)2(bpy)2(OH)(NO3)
[Mn2O(m-AcO)2(bpy)2(H2O)2]+
2.077
2.056
2.073
2.071
1.773
1.806
1.777
1.797
2.001
2.172
1.933
2.130
1.971
2.158
1.943
2.170
1.936
1.939
2.180
125.2(6)
a
a
2.191
121.8(2)
2.15 b
124.12(11)
122.7(2)
[3b]
[3a]
2.286
[Mn2O(m-AcO)2(bpy)2(H2O)2]+
3.139
3.137(2)
2.064
2.069
1.787
1.786
2.315
2.224
123.0
122.9
[3c]
[3c]
[Mn2O(m-AcO)2(bpy)2(H2O)(NO3)]+
a This work.
b MnꢀOH.
Mn2···Mn2 moieties. In addition, to link to the NO3−
other by at least 7.49 A. It is believed that the two
Mn(II) ions do not undergo magnetic exchange interac-
tion though the hydrogen bonding interactions were
found between the two molecules. The magnetic prop-
erties of 1 are illustrated as the temperature dependence
,
,
,
group (O45···O21, 2.863 A; O45···O23, 2.874 A) coordi-
nated to the Mn2···Mn2 moiety, O45 links to COOH in
,
the adjacent Mn2···Mn2 moiety (O45···O18A, 2.822 A),
leading to the formation of molecular polymeric chains.
A projection of the crystal packing is shown in Fig. 4,
exhibiting the network structure of hydrogen bonding
interactions for compound 2.
Table 5
,
Hydrogen bonding interactions (A) in inclusion compound 2
O24···O22
O24···O4
O45···O21
O45···O23
O44···O18A
O2···O42
O12···O41
O43···O19
O43···O17
O44···O9
2.865
2.860
2.863
2.874
2.822
2.689
2.629
2.499
2.791
2.579
2.872
Ligand to ligand H2O···NO3
Ligand to ligand H2O···COOH
Solvent to ligand H2O···NO3
Solvent to ligand H2O···NO3
Solvent to ligand H2O···COOH
Ligand to solvent H2O···H2O
Ligand to solvent H2O···H2O
Solvent to ligand H2O···COOH
Solvent to ligand H2O···COOH
Solvent to ligand H2O···COOH
Solvent to ligand H2O···COOH
3.3. Electrochemistry
The electrochemical property of the inclusion com-
pound 2 has been examined by cyclic voltammetry
shown in Fig. 5. A quasi-reversible redox was observed
at +0.10/+0.22 V with broadened features. The ex-
change equilibrium between monodentate ligands and
the solvent may make broad features for cyclic voltam-
metry. In comparison with the behavior of the other
Mn2(III)(m-O)1–2(RCOO)2–1 species, [3a,4,11] the redox
of compound 2 occurs in more negative potential.
However, on the oxidation side, the scan to +2.0 V
has not found additional oxidation features. So the
redox at +0.10/+0.22 V would be assigned to the
Mn(III)2/Mn(III)Mn(IV) couple. Interestingly, com-
pound 2 exhibits the other quasi-reversible redox at
−0.43/−0.36 V, showing more abundant redox fea-
tures. It is considered that the participation of the
dicarboxylic acid varies the electrochemical behavior of
the Mn(III)2 unit by intra- and intermolecular hydrogen
bonding interactions which stabilize the Mn(III)2 unit
so as to avoid damage in the reduction process. The
redox at −0.43/−0.36 V could be tentatively assigned
to the Mn(III)Mn(II)/Mn(III)2 couple.
O44···O7
3.4. Magnetic properties
Compound 1 consists of two mononuclear Mn(II)
molecules. The two Mn(II) ions belonging to the re-
spective molecules keep themselves apart from each
Fig. 4. Packing diagram of unit cell of 2·5H2O, showing the network
structure formed by hydrogen bonding interactions.

C. Chen et al. / Inorganica Chimica Acta 320 (2001) 159–166
165
Fig. 5. Cyclic voltammogram of 2 (1 mM) in DMF with scan speed
200 mV s−1. Peak potentials are indicated.
Fig. 7. Experimental molar susceptibility (M) and effect magnetic
moment (veff) of temperature dependence for compound 2. The solid
line represents the calculated values.
and F=1.48×10−5. This fitting result supports the
occurrence of significant zero-field splitting in the
Mn(II) ions.
The magnetic behavior of 2 is represented in Fig. 7 as
the temperature dependence of veff and M, respectively.

M
is the corrected molar magnetic susceptibility per
Mn2···Mn2 unit. At room temperature veff is equal to
9.65 BM close to that expected for uncoupled four
S=2 spins (9.79 BM for gMn=2). The effective mag-
netic moment smoothly increases with the decrease of
Fig. 6. Experimental molar susceptibility (M) and effect magnetic
moment (veff) of temperature dependence for compound 1. The solid
line represents the calculated values.
the temperature, reaching a maximum value (veff
=
10.78 BM) around 14 K, and finally slightly decreases
below 14 K. This behavior is quite characteristic of a
ferromagnetic interaction between the neighboring
Mn(III) ions. The structure of the complex consists of
both virtually isolated and very similar binuclear Mn2
units. The expected veff value of 12.65 BM is not
reached for two isolated S=4 ground states, indicating
zero-field splitting effect in the ground state for per
binuclear Mn2 unit. To take this effect into account, an
of the effective magnetic moments (veff) and molar
susceptibilities (M) in Fig. 6. At room temperature, veff
amounts to 8.32 BM, which is the value expected for
two independent spins S=5/2 (8.37 BM for g=2).
When the temperature decreases in the range 300–30
K, the veff value remains quite constant (8.32–8.29
BM). At lower temperature (TB30 K), a decrease in
veff was observed, which may arise from zero-field
splitting of S=5/2. To take this effect into account, the
theoretical expression of magnetic susceptibility for the
complex is as follows:
expression of the magnetic susceptibility  of the
bi
binuclear Mn2 unit was used from the spin Hamiltonian
in zero field. This expression is based on the fact that
only zero-field splitting for the ground state was consid-
ered [12] and that the Zeeman splitting was treated
isotropically for the sake of simplicity [13]:
Ng2i2 1+9 exp(−2D/KT)+25 exp(−6D/KT)
ꢃ
n
z
ꢂ=
4KT
1+exp(−2D/KT)+exp(−6D/KT)
(1)
Ng2i2 (9/KT+8/D)−11 exp(−2D/KT)/2D−5 exp(−6D/KT)/2D
ꢃ
n
x
Þ=
(2)
(4)
4
1+exp(−2D/KT)+exp(−6D/KT)
2Þ+
ꢂ
=
(3)
2
.
.
.
H= −2JS1·S2−D[SZ−S(S+1)/3]
3
where D is the axial zero-field splitting parameter for
the Mn(II) ion and gx=gz=g. A least-squares fitting
of the experimental data led to D=1.77 cm−1, g=1.98
where D is the axial zero-field splitting parameter for
the S=4 state. Using Eq. (4), a susceptibility equation
for the binuclear Mn2 unit is given as follows:

166
C. Chen et al. / Inorganica Chimica Acta 320 (2001) 159–166
[3] (a) J.B. Vincent, H.L. Tsai, A.G. Blackman, S. Wang, P.D.W.
2Ng2i2
KT
A
B
ꢃ n
bi=
(5)
Boyd, K. Folting, J.C. Huffman, E.B. Lobkovsky, D.N. Hen-
drickson, G. Christou, J. Am. Chem. Soc. 115 (1993) 12353;
(b) M. Corbella, R. Costa, J. Ribas, P.H. Fries, J.-M. Latour, L.
28D
3KT
7D
−8D
ꢄ ꢅ ꢄ ꢅ ꢄ ꢅ
A=16 exp
+9 exp
+4 exp
3KT
−8J
3KT
−14J
8
Ohrstro¨m, X. Solans, V. Rodr´ıguez, Inorg. Chem. 35 (1996)
1857;
−17D
ꢄ ꢅ ꢄ ꢅ ꢄ ꢅ
(c) K.R. Reddy, M.V. Rajasekharan, S. Sukumar, Polyhedron
23 (1996) 4161;
(d) S. Me´nage, J.J. Girerd, A. Gleizes, J. Chem. Soc., Chem.
Commun. (1988) 431;
+exp
+14 exp
+5 exp
3KT
KT
KT
−18J
ꢄ ꢅ
+exp
KT
(e) J.B. Vincent, K. Folting, J.C. Huffman, G. Christou,
Biochem. Soc. Trans. 16 (1988) 822;
(f) A.G. Blackman, J.C. Huffman, E.B. Lobkovsky, G. Christou,
J. Chem. Soc., Chem. Commun. (1991) 989.
[4] (a) K. Wieghardt, U. Bossek, D. Ventur, J. Weiss, J. Chem. Soc.,
Chem. Commun. (1985) 347;
−20D
3KT
28D
7D
3KT
ꢄ ꢅ ꢄ ꢅ ꢄ ꢅ
B=exp
+2 exp
+2 exp
3KT
−17D
−8D
3KT
−8J
KT
ꢄ ꢅ ꢄ ꢅ ꢄ ꢅ
+2 exp
+2 exp
+7 exp
3KT
(b) J.E. Sheats, R.S. Czernuszewicz, G.C. Dismukes, A.L.
Rheingold, V. Petrouleas, J. Stubbe, W.H. Armstrong, R.H.
Beer, S.J. Lippard, J. Am. Chem. Soc. 109 (1987) 1435;
(c) K. Wieghardt, U. Bossek, B. Nuber, J. Weiss, J. Bonvoisin,
M. Corbella, S.E. Vitols, J.J. Girerd, J. Am. Chem. Soc. 110
(1988) 7398;
−14J
KT
−18J
−20J
ꢄ ꢅ ꢄ ꢅ ꢄ ꢅ
+5 exp
+3 exp
+exp
KT
KT
For 2 containing tetranuclear manganese, which con-
sists of two independent binuclear Mn2 units, the mag-
netic susceptibility equation becomes
(d) F.J. Wu, D.M. Kurtz, K.S. Hagen, P.D. Nyman, P.G.
Debrunner, V.A. Vankai, Inorg. Chem. 29 (1990) 5174;
(e) S. Mahapatra, T.K. Lal, R. Mukherjee, Inorg. Chem. 33
(1994) 1579;
4Ngi2
KT
A
ꢃ n
tetra=2bi=
(6)
B
(f) K. Wieghardt, U. Bossek, J. Bonvoisin, P. Beauvillain, J.J.
Girerd, B. Nuber, J. Weiss, J. Heinze, Angew. Chem., Int. Ed.
Engl. 25 (1986) 1030.
The least-squares fitting of the experimental data led
to J=2.37 cm−1, g=2.02 and D=0.75 cm−1 with
R=1.45×10−3. As reported in literature [3a,b,4a,d]
for a series of (m-oxo)bis(m-carboxylato)dimanganese-
(III) complexes, the two Mn(III) ions undergo a weak
magnetic exchange interaction in the range −5BJB
10 cm−1. It should be pointed out that the values for D
and J are overall values. In the case of the coexistence
of two Mn2 sites in compound 2, the different Mn sites
may cause the change of the J value. Refering to other
dinuclear Mn(III) analogs, weak magnetic exchange
occuring between the Mn(III) sites is expected for com-
pound 2. However, it is difficult to discuss precisely
which structural features will result in the weak ferro-
magnetic exchange for compound 2. A further study
will be required.
[5] (a) R.C. Squire, S.M.J. Aubin, K. Folting, W.E. Streib, G.
Christou, D.N. Hendrickson, Inorg. Chem. 34 (1995) 6463;
(b) M.W. Wemple, H.L. Tsai, S. Wang, J.P. Clude, W.E. Streib,
J.C. Huffman, D.N. Hendrickson, G. Christou, Inorg. Chem. 35
(1996) 6437;
(c) Z.-H. Jiang, S.-L. Ma, D.-Z. Liao, S.-P. Yan, G.-L. Wang,
X.-K. Yao, R.-J. Wang, J. Chem. Soc., Chem. Commun. (1993)
745.
[6]
M
olEN, An Interactive Structure Solution Procedure, Enraf–No-
nius, Delft, The Netherlands, 1990.
[7] G.M. Sheldrick, SHELXTL 93, Program for the Refinement of
-
Crystal Structure, University of Go¨ttingen, Germany.
[8] (a) X.-M. Chen, X.-Y. Huang, Y.-J. Xu, Y.-J. Zhu, J. Chem.
Crystallogr. 25 (1995) 605;
(b) X.-M. Chen, R.-Q. Wang, Z.-T. Xu, Acta Crystallogr., Sect.
C 51 (1995) 820;
(c) X.-M. Chen, K.-L. Shi, Acta Crystallogr., Sect. C 51 (1995)
358;
(d) P.O. Lumme, E. Lindell, Acta Crystallogr., Sect. C 44 (1988)
463;
(e) X.-L. Yu, Y.-X. Tong, X.-M. Chen, T.C.W. Mak, J. Chem.
Crystallogr. 27 (1997) 441.
Acknowledgements
This work was supported by State Key Basic Re-
search and Development Plan of China (G1998010100)
and NNSFC (Nos. 29733090, 29973047 and 39970177).
[9] C. Philouze, M. Henry, N. Auger, D. Vignier, M. Lance, M.
Nierlich, J.-J. Girerd, Inorg. Chem. 38 (1999) 4.
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