Self-assembly of a pentanuclear {Cu5} complex resulting from the trapping of a Cu2+ ion by two {Cu2} building units

Article abstract of DOI:10.1016/j.poly.2013.02.051

The compound [Cu₅(μ₃-OH)₂(H ₂bpmp)₂(μ_1,1-OAc)₂(μ _1,1,3-OAc)₂(OAc)₂]·2H₂O (1·2H₂O) (H₃bpmp = 2,6-bis-[(3-hydroxy-

Full text of DOI:10.1016/j.poly.2013.02.051

Accepted Manuscript
Self-Assembly of a Pentanuclear {Cu } Complex Resulting from the Trapping
5
2+
of a Cu Ion by Two {Cu } Building Units
2
Aloke Kumar Ghosh, Rodolphe Clérac, Corine Mathonière, Debashis Ray
PII:
S0277-5387(13)00153-8
DOI:
http://dx.doi.org/10.1016/j.poly.2013.02.051
POLY 9960
Reference:
To appear in:
Polyhedron
Received Date:
Accepted Date:
9 January 2013
15 February 2013
Please cite this article as: A.K. Ghosh, R. Clérac, C. Mathonière, D. Ray, Self-Assembly of a Pentanuclear {Cu5}
2+
Complex Resulting from the Trapping of a Cu Ion by Two {Cu } Building Units, Polyhedron (2013), doi: http://
2
dx.doi.org/10.1016/j.poly.2013.02.051
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1
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Self-Assembly of a Pentanuclear {Cu } Complex Resulting from the Trapping
5
2+
of a Cu Ion by Two {Cu } Building Units
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[
a]
[b,c]
[d,e]
[a]
Aloke Kumar Ghosh, Rodolphe Clérac, Corine Mathonière and Debashis Ray*
[a]
Department of Chemistry, Indian Institute of Technology, Kharagpur 721 302, India
Fax: (+91) 3222-82252; Tel: (+91) 3222-283324; E-mail: dray@chem.iitkgp.ernet.in
[b]
[c]
[d]
[e]
CNRS, CRPP, UPR 8641, Pessac, F-33600, France.
Univ. Bordeaux, CRPP, UPR 8641, Pessac, F-33600, France.
CNRS, UPR 9048, ICMCB, Pessac, F-33600, France
Univ. Bordeaux, ICMCB, UPR 9048, Pessac, F-33600, France.
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Abstract
The compound [Cu
5
(µ
3
-OH)
2
(H
2
bpmp)
2
(µ1,1-OAc)
2
(µ1,1,3-OAc)
2
(OAc)
2
]·2H
2
O
2
(1·2H O)
(H
defective cubanes at a Cu vertex, has been obtained via µ
two dinuclear Cu(II) phenoxido-bridged {Cu (H bpmp)} fragments. Antiferromagnetic
interactions within the complex lead to an S = ½ ground state for the pentanuclear arrangement.
3
bpmp = 2,6-bis-[(3-hydroxy-propylimino)-methyl]-4-methyl-phenol), featuring two fused
2
+
3
-OH-bridge-driven self-assembly of
2
2
T
Keywords. Self-assembly / pentanuclear / trapping / Schiff base / hydroxido and acetato bridges
/ antiferromagnetic interactions
Page 1 of 53

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6
1. Introduction
In recent years, high-nuclearity coordination complexes have attracted major interest in the
areas of both synthetic chemistry and molecular magnetism [1,2]. The synthetic strategy
2
involving the self-assembly processes of dinuclear {Cu } building blocks around a central oxido
or metal ion and appropriate bridging/blocking ligands is a fascinating approach as the final
outcome can never be totally predicted beforehand [3]. Because of the biological and
biochemical importance of multicopper oxidase enzymes as dominant oxidizing agents toward
different substrates in laccase [4,5], ascorbate oxidase and nitrite reductase [6], the understanding
and synthetic control of the chemical aggregation of multi-copper coordination complexes is one
of the major research areas in coordination chemistry [7]. Such coordination compounds are in
general prepared via metal ion coordination driven self-assembly reactions with the use of
suitable bridging and blocking ligands [8]. Among these Cu-based systems, the pentanuclear
assembly with a ‘vertex-shared defective dicubane’ core is not commonly encountered [9]. In
5
these {Cu } systems, the vertices are composed of either metal ions or oxygen donor atoms from
oxido, hydroxido or acetato groups. Existing copper complexes involving all these three ligands
as bridges and comprising multiple fused cubanes are extremely scarce [10a-d]. In this
perspective, the reactivity of hexadenate/dinucleating phenolate Schiff base ligands like H
(Chart 1, 2,6-bis-[(3-hydroxy-propylimino)-methyl]-4-methyl-phenol) with copper(II) in the
presence of acetate anions have been explored. The use of the H bpmp ligand in transition-metal
3
bpmp
3
chemistry is relatively new, the only compound known is a dinuclear hydroxido-bridged
copper(II) complex [11,12]. It is worth noting that use of two closely related ligands, Hbip and
Hcip (Chart 1, R = benzyl; Hbip: 2,6-bis(benzyl imino methyl)-4-methylpheno and R =
cyclohexyl; Hcip: 2,6-bis(cyclohexyl imino methylene)-4-methylphenol), led to interesting
Page 2 of 53

4
4
4
5
7
8
9
0
systems, consisting of {Cu
4
} complexes, showing chemical reactivity and core conversion
reactions [13,14].
Chart 1.
5
5
1
2
5
5
5
5
5
5
5
6
6
6
6
6
6
6
3
4
5
6
7
8
9
0
1
2
3
4
5
6
In this work, the coordinating and aggregating abilities of H
3
bpmp (Scheme S1), together with
the varying binding properties of acetate ions, have been exploited for the preparation of a novel
5 3 2 2 2 2 2 2 2 2
pentanuclear complex, [Cu (µ -OH) (H bpmp) (µ1,1-OAc) (µ1,1,3-OAc) (OAc) ]·2H O (1·2H O).
2. Experimental Section
2.1 Materials and Physical Methods.
The chemicals used were obtained from the following sources: copper(II) acetate monohydrate
from S.D. Fine Chemicals, triethylamine from Merck, India and 3-amino-1-propanol from
Aldrich Chemical Co. Inc. US. All other chemicals and solvents were reagent-grade materials
and were used as received without further purification. 2,6-Diformyl-4-methylphenol (2-
hydroxy-5-methyl-benzene-1,3-dicarbaldehyde) was prepared following a literature procedure
[15]. The elemental analyses (C, H, N) were performed with a Perkin-Elmer model 240 C
elemental analyzer. Fourier transform infrared (FTIR) spectra were recorded on a Perkin-Elmer
RX1 spectrometer. Solution electrical conductivity measurements and electronic spectra were
Page 3 of 53

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0
1
2
3
4
5
6
7
8
9
0
1
2
3
carried out using a Unitech type U131C digital conductivity meter with a solute concentration of
-3
about 10 M and a Shimadzu UV 3100 UV-vis-NIR spectrophotometer, respectively. The
magnetic susceptibility measurements were obtained with the use of a Quantum Design SQUID
magnetometer, MPMS-XL. This magnetometer works between 1.8 and 400 K for dc applied
fields ranging from -7 to 7 T. Measurements were performed on microcrystalline samples of
2
22.13 mg for 1·2H O. The magnetic data are corrected for the sample holder and the diamagnetic
contributions.
2.2 Synthesis
3 3
H bpmp Ligand. The H bpmp Schiff-base ligand was prepared from the single step
condensation of 2,6-diformyl-4-methylphenol (1.0 g, 6.1 mmol) and 3-amino-1-propanol (0.91 g,
12.2 mmol) in methanol (20 mL) in air at room temperature (28 °C), under stirring for 2 h.
Complete evaporation of the solvent in air over 12 h yielded an orange colored semi-solid
product which was used directly for the reaction without further characterization. Yield: 1.32g
(78%).
5 3 2 2 2 2 2 2
[Cu (µ -OH) (µ-bpmp) (µ1,1-OAc) (µ1,1,3-OAc) (OAc) ]·2H O.
8
8
8
8
8
8
4
5
6
7
8
9
A methanolic solution (10 mL) of Cu(OAc)
2
·H
2
O (0.599 g, 3.00 mmol) was slowly added to the
(139
H
3
bpmp ligand (0.278 g, 1.00 mmol) in methanol (20 mL), followed by addition of NEt
3
mL, 0.101 g, 1.00 mmol). The resulting solution was stirred for 2 h at room temperature. The
solvent was evaporated in air to give a green solid that was isolated, washed with cold methanol
4
and dried under vacuum over P O10. Green crystals suitable for X-ray analysis were obtained
5 4 22
from a MeOH solution after two weeks. Yield: 0.492 g, 76%. Anal. Calcd. for C42H66Cu N O
Page 4 of 53

-
1
9
9
9
0
1
2
(1296.71 g mol ): C, 38.90; H, 5.13; N, 4.32. Found: C, 38.82; H, 5.22; N, 4.22. Selected FT-IR
-
1
bands (KBr, cm ; s = strong, vs = very strong, m = medium, br = broad): 3387(br), 2926(s),
1638(s), 1578(s), 1396(vs), 1334(s), 1076(vs), 918(m), 681(m), Molar conductance, (MeOH
M
-
1
2
-1
-1
-1
9
9
3
4
solution, Ω cm mol ): 6.3. UV-vis spectra [ max, nm ( , L mol cm )] (MeOH solution) : 666
(235), 370 (5120), 210 (17700).
9
9
5
6
2.3 X-ray crystallography
9
9
9
7
8
9
The diffraction data of the complex 1·2H
diffractometer using single crystals, with graphite-monochromated Mo-K
Å) by the -scan method at 293 K. Information concerning X-ray data collection and structure
refinement of the compound is summarized in Table 1. For complex 1·2H O, a total of 7960
2
O was collected on a Bruker APEX-II CCD X-ray
α
radiation (λ = 0.71073
1
1
1
1
00
01
02
03
2
reflections were recorded with Miller indices hmin = -16, hmax = 16, kmin = -19, kmax = 20, lmin = -
2
23, lmax = 22 .In the final cycles of full-matrix least squares on F , all non-hydrogen atoms were
assigned anisotropically. The structure was solved using the SHELX-97 [16] program system.
1
04
2
Table 1. Crystallographic data for 1·2H O
compound
formula
M
2
1·2H O
42 5 4 22
C H66Cu N O
1296.71
space group
crystal system
a/Å
P 2 /c
1
monoclinic
11.4604(7)
13.7598(8)
17.3334(10)
103.317(2)
b/Å
c/Å
β/deg
Page 5 of 53

3
V/Å
T/K
Z
2659.85(3)
293
3
-3
D
c
/g cm
F(000)
crystal size/mm
1.619
1334
0.36 x 0.25 x 0.15
20.47
-1
µ(Mo-Kα)/cm
measured Refl.ns
unique Ref.ns
39472
7960
R
int
0.0377
obs. refl.ns I≥2σ(I) 5671
θ
min- θmax/°
1.83 -31.86
hkl ranges
-16, 16;-19, 20; -23,22
0.0367
2
R(F ) (obs.refl.ns)
2
wR(F ) (all refl.ns) 0.1009
no. variables
GOF
347
1.026
-3
∆ρmax; ∆ρmin (e Å ) 0.621; -0.481
2
2 1/2
2
2
1
1
05
06
1 o c o 2 o c o o o
R = ( F F )/ F . wR = [ w( F F ) / w(F ) ] . w = 0.75/( (F ) +0.0010F ).
1
1
1
1
1
1
1
1
07
08
09
10
11
12
13
14
3. Results and Discussion
3.1 Synthetic Considerations. H
following a reported procedure, [17] and its reactions with copper(II) salts have been
3
bpmp was prepared (Scheme S2 in the Supporting Information)
investigated (Scheme 1). The reaction of Cu(OAc)
2
·H
2
O with H
3
bpmp in MeOH and NEt
3
gave
was
[Cu (µ-H bpmp) (µ -OH) (OAc)
5
2
2
3
2
(µ1,1-OAc)
2
(µ1,1,3-OAc)
2
2
]·2H O. Complex 1·2H O
2
2
obtained as a precipitate in 76% yield from MeOH, as summarized in eq. 1, clearly accounting
for the formation the two hydroxido bridges from water molecules present in the organic solvent
medium. The elemental analysis, molar conductivity and single-crystal X-ray diffraction (vide
Page 6 of 53

1
1
15
16
infra) data confirm the given formula [Cu
5 2 2 3 2 2 2 2
(µ-H bpmp) (µ -OH) (µ1,1-OAc) (µ1,1,3-OAc) (OAc) ]
for 1.
1
1
17
18
Scheme 1. Schematic representation of the non-formation of {Cu2} and {Cu4}, and formation of
{Cu } assemblies
1
1
1
1
1
1
1
1
19
20
21
22
23
24
25
26
5
4H
3
bpmp + 5Cu
2
(OAc)
4
·2H
2
O + 8NEt
3
2[Cu
5
(µ-H
2
bpmp)
2
(µ -OH)
3
2
(µ1,1-OAc)
2
(µ1,1,3-OAc)
2
(OAc)
2 2
]·2H O
+ 8(HNEt
3
)(OAc) + 2H
2
O
···· (1)
5 2
The vertex-shared {Cu }complex 1 results from the binding of two µ-H bpmp ligands in front of
II
a Cu /AcO system, as opposed to tetranuclear or dinuclear complexes (Scheme 1).
1
1
1
27
28
29
3.2 Description of the Crystal Structure. The crystallographic asymmetric unit consists of one-
2
half of the pentanuclear unit and one interstitial solvent H O molecule. The second half of the
Page 7 of 53

1
1
1
1
1
30
31
32
33
34
complex is generated from the above mentioned unit by symmetry operations (-x, 1-y, -z).
II
Complex 1 is a centrosymmetric pentanuclear Cu species formed of two defective cubanes
II
around the central Cu , with a [Cu
5
O10] core (Figures 1 and S1-S4). Important bond lengths and
2
Table 2. Selected inter-atomic distances (Å) and angles (º) for the complex 1·2H O
Distances
O(3)-Cu(2)
O(4)-Cu(1)
Cu(1)-O(2)
Cu(1)-O(2)*
Cu(1)-O(6)
Cu(1)-O(6)*
Cu(1)-O(4)*
Cu(1)-Cu(2)
Cu(1)-Cu(2)*
Cu(2)-O(2)
1.925(1)
2.253(1)
1.981(1)
1.981(1)
2.009(1)
2.009(1)
2.253(1)
2.969(3)
2.969(3)
1.9325(1)
Cu(2)-N(1)
Cu(2)-O(1)
Cu(2)-O(6)*
Cu(2)-Cu(3)
Cu(3)-O(2)
Cu(3)-O(8)
Cu(3)-N(2)
Cu(3)-O(1)
O(6)-Cu(2)
1.953(2)
1.970(1)
2.376(1)
3.058(4)
1.930(1)
1.935(1)
1.941(2)
1.984(1)
2.376(1)
Angles
O(2)-Cu(1)-O(2)*
O(2)-Cu(1)-O(6)*
O(2)*-Cu(1)-O(6)* 92.8(7)
O(2)*-Cu(1)-O(6)
O(2)*-Cu(1)-O(6)
O(6)-Cu(1)-O(6)*
O(2)-Cu(1)-O(4)*
O(2)-Cu(1)-O(4)
180.0
87.1(7)
O(2)-Cu(2)-N(1)
O(3)-Cu(2)-O(1)
O(2)-Cu(2)-O(1)
N(1)-Cu(2)-O(1)
O(3)-Cu(2)-O(6)*
O(2)-Cu(2)-O(6)*
N(1)-Cu(2)-O(6)*
O(1)-Cu(2)-O(6)*
O(3)-Cu(2)-Cu(1)
O(2)-Cu(2)-Cu(1)
N(1)-Cu(2)-Cu(1)
O(1)-Cu(2)-Cu(1)
O(6)*-Cu(2)-Cu(1)
O(3)-Cu(2)-Cu(3)
O(2)-Cu(2)-Cu(3)
N(1)-Cu(2)-Cu(3)
O(1)-Cu(2)-Cu(3)
O(6)*-Cu(2)-Cu(3)
Cu(1)-Cu(2)-Cu(3)
O(2)-Cu(3)-O(8)
O(2)-Cu(3)-N(2)
O(8)-Cu(3)-N(2)
O(2)-Cu(3)-O(1)
O(8)-Cu(3)-O(1)
170.4(7)
166.3(7)
77.1(6)
93.3(7)
102.2(7)
78.6(6)
100.3(7)
86.0(6)
84.7(5)
41.2(5)
140.9(6)
94.5(4)
42.3(4)
130.5(5)
37.6(5)
132.8(6)
39.5(4)
80.2(4)
63.9(7)
94.6(7)
167.4(8)
97.1(8)
76.8(6)
167.2(7)
92.8(7)
87.1(7)
180.0
88.8(6)
91.1(6)
O(6)*-Cu(1)-O(4)* 87.3(7)
O(6)*-Cu(1)-O(4)
O(2)-Cu(1)-O(4)
O(2)*-Cu(1)-O(4)
O(6)*-Cu(1)-O(4)
O(6)*-Cu(1)-O(4)* 87.3(7)
O(4)*-Cu(1)-O(4)
O(2)-Cu(1)-Cu(2)
O(2)-Cu(1)-Cu(2)* 139.9(5)
O(6)*-Cu(1)-Cu(2) 52.8(4)
O(6)*-Cu(1)-Cu(2)* 127.1(4)
O(4)-Cu(1)-Cu(2)* 105.2(4)
O(4)-Cu(1)-Cu(2)
O(2)*-Cu(1)-Cu(2) 139.9(5)
O(2)*-Cu(1)-Cu(2)* 40.0(5)
92.6(7)
91.1(6)
88.8(6)
92.6(7)
180.0
40.0(5)
74.7(4)
O(6)-Cu(1)-Cu(2)
127.1(4)
O(6)-Cu(1)-Cu(2)* 52.8(4)
N(2)-Cu(3)-O(1)
92.1(7)
Page 8 of 53

O(4)-Cu(1)-Cu(2)
O(4)*-Cu(1)-Cu(2) 105.2(4)
Cu(2)-Cu(1)-Cu(2)* 180.0
O(3)-Cu(2)-O(2)
O(3)-Cu(2)-N(1)
Cu(3)-O(2)-Cu(1)
74.7(4)
O(2)-Cu(3)-Cu(2)
O(8)-Cu(3)-Cu(2)
N(2)-Cu(3)-Cu(2)
O(1)-Cu(3)-Cu(2)
Cu(3)-O(2)-Cu(2)
Cu(2)-O(2)-Cu(1)
37.6(5)
131.6(5)
131.0(6)
39.1(4)
104.6(8)
98.6(7)
93.6(7)
95.8(7)
109.3(8)
*
: -x, 1-y,- z
1
35
1
1
36
37
angles are listed in Table 2, where the bridges between the metal ions are ensured by two water
derived µ -OH anions, four acetato ligands (two each in µ1,1,3, µ1,1 modes) and two µ-phenoxido
moieties from deprotonated H bpmp ligands.
3
1
1
38
39
2
1
1
40
41
5 2 2 3 2 2
Figure 1. View of the pentanuclear unit of [Cu (µ-H bpmp) (µ -OH) (µ1,1-OAc) (µ1,1,3-
1
1
1
1
1
1
42
43
44
45
46
47
OAc) (OAc) ]·2H O in 1·2H
2
2
2
2
O
6
The central Cu(1) adopts an octahedral coordination sphere with an O donor environment
made from the coordination of hydroxido (O(2)) and acetate (O(4) and O(6)) groups, having long
Cu(1)-O(4) apical bonds (2.253 Å) as expected from a Jahn-Teller distortion along the z axis.
II
(Figure S5). The remaining coordination sites of the square pyramidal Cu ions (Addison [18] τ
Page 9 of 53

1
1
48
49
values 0.06 and 0.003) are completed by peripheral imine groups from H
2
bpmp ligands.
Interestingly, both the alcohol arms of the ligand H bpmp remain uncoordinated and one of them
2
1
1
1
50
51
52
is engaged in inter-molecular hydrogen-bonding interactions with water molecules of
crystallization (Figure S6). The other uncoordinated arms show intra-molecular hydrogen-
bonding interactions with free carbonyl oxygen atoms of bridging µ1,1 acetate groups. There are
1
1
1
53
54
55
all together three different types of acetate groups present in the compound (Figure S7). The
affinity of the copper(II) ions for long distance binding along the apical Jahn-Teller axis is
responsible for the binding of six AcO ions in these three different modes. Inspection of Figure 1
1
1
1
1
1
1
1
1
56
57
58
59
60
61
62
63
suggests that the formation of 1 occurs through the trapping of an [Cu(OAc)
two hitherto unknown {Cu } fragments, [Cu (µ-H bpmp) (µ-OH)(OAc) ]. During this assembly,
the double hydroxido bridge of the {Cu } fragments extends its binding capacity to µ -OH and
one of the acetato group to µ1,1-OAc. The trapped acetato groups of [Cu(OAc) (H O) ] are
converted to the µ1,1 mode and one acetato group on each metal ion of the {Cu } fragments is
2 2 2
(H O) ] species by
2
2
2
2
2
2
3
2
2
2
2
transformed to the µ1,1,3 mode. Three different types of acetato ligands in µ1,1,3, µ1,1 and
monodentate binding modes stabilize the coordination complex by satisfying the geometry and
coordination demands of the copper(II) centers. These three different types of AcO binding
1
1
1
1
1
64
65
66
67
68
modes in a single acetate rich complex are rather exceptional. The two hydroxido bridges have
the primary control on the formation of the {Cu
minerals shattuckite, Cu (OH) (SiO , cornubite, Cu
hydroxide in the copper selenite chloride compound, Cu
5
} entity, like that observed in the copper-based
5
2
3
)
4
5
(OH)
2
(AsO
4
)
2
and chloride in the place of
II
5
Cl
2
(SeO
3
)
4
[19a,b]. The five Cu atoms
of the complex are at five vertices of a ‘vertex shared opened-dicubane’ [20], where one vertex
Page 10 of 53

1
1
1
1
1
69
70
71
72
73
of each cubane is missing and the octahedral copper(II) center occupies a mutual vertex of each
opened-cubane (Figure S8).
3.3 FT-IR Spectroscopy. The presence of lattice uncoordinated alcohol groups, lattice water
molecules and hydroxido ligands in 1 is manifested by one broad band of medium intensity at
-
1
ν
3387 cm , assigned to (OH). The broadness and relatively low frequency are both indicative
1
1
74
75
-1
of hydrogen bonding. Several bands for 1 also appear in the 1638 1396 cm region for this
ν
ν as
ν s
(COO) and (COO) are expected in this
1
76
complex. Contributions from (C=N), (OH),
1
1
77
78
region for three different types of acetato coordination, but overlap with the stretching vibrations
of the aromatic ring of the ligand occasionally renders the assignments and discussion of the
ν C=N
1
1
79
80
shifts of the stretching frequencies during coordination difficult. The
stretching frequency
-l
-1
is observed at 1638 cm for complex 1. The bands at 1578 and 1396 cm in the spectrum of 1
ν as
ν s
(COO) carboxylate modes, respectively. The
1
1
81
82
are tentatively assigned to the
(COO) and
-1
ν as
ν s
(COO), is 182 cm as expected for the µ1,1,3-bridging
parameter , where =
(COO)
1
1
1
1
1
1
1
83
84
85
86
87
88
89
mode of the acetate ligation [20]. As noted earlier, the bands assignable to µ1,1-bridging and non-
bridging modes are difficult to assign in this range.
3.4 Electronic UV-Vis Spectra. Complex 1 in MeOH solution shows multiple bands in the 900-
-1
-1
200 nm region. A broad absorption band (λ), with a maximum at 666 nm (ε = 235 L mol cm )
for 1, is due to a d-d transition, available for copper(II) bound to the H bpmp ligand. A shoulder
3
-1
-1
-
II
-
II
at 370 nm (ε = 5120 L mol cm ), for this complex is possibly due to HO Cu and PhO Cu
Page 11 of 53

1
1
90
91
ligand-to-metal charge transfer (LMCT) transitions [21]. The intense absorption at 210 nm (ε =
-1
-1
17700 L mol cm ) for 1 is from intraligand π π * transitions.
1
1
1
1
1
1
1
1
2
2
2
2
92
93
94
95
96
97
98
99
00
01
02
03
2
3.5 Magnetic Properties: The solid-state magnetic properties of 1·2H O were investigated using
dc susceptibility measurements in the 1.8-300 K temperature range under a magnetic field of 1 T.
3
-1
At room temperature, the χT product is 0.89 cm K mol . This χT value is far from the theoretical
3
-1
2+
9
value of 1.875 cm K mol expected for five isolated paramagnetic Cu ions (d , S = ½) with g
2
+
= 2, indicating that strong and dominant antiferromagnetic interactions exist between the Cu
ions in the complex. Upon cooling, the χT product continuously decreases to reach a value close
to 0.47 below 70 K. Using the structure of 1 as a guide, the complex can be viewed as an
assembly of dinuclear units, each formed by the two external Cu(II) ions, linked together by a
central Cu(II) ion. The bridging geometry in the dinuclear units is made of one µ-phenoxido and
3
one µ -hydroxido group, with Cu(2)-O(2)-Cu(3) and Cu(2)-O(1)-Cu(3) angles of 104.69 and
101.31°, respectively (Figure 2).
2
2
04
05
2
Figure 2. The metallic core of 1·2H O
II
2
2
2
06
07
08
Generally speaking for the Cu ions, the magnetic interactions mediated through their apical
positions are much weaker than those mediated by their basal sites. Therefore, if one considers
II
only the magnetic pathways that involve basal bonds around each Cu ion, 1 can be viewed as
Page 12 of 53

II
2
2
2
2
2
09
10
11
12
13
the sum of two dinuclear units linked by a central Cu ion. As a consequence, the complex can
II
be topologically viewed as two spin dimers composed of two S = ½ Cu ions and one isolated S
II
= ½ spin (the central Cu ion). As a first approximation, the magnetic data were modelled using
an isotropic spin Heisenberg Hamiltonian to estimate the value of the exchange interaction in
each dimmer, as given in eq. 2.
2
14
H = −2J S • S
(2)
{
}
Cu,1
Cu,2
2
2
2
2
15
16
17
18
i
where, J is the exchange interaction within the dinuclear Cu(II) units; S the spin operators for
each center with S = ½. The application of the van Vleck equation [22,23] allows the
determination of the low field analytical expression of the magnetic susceptibility, including the
Curie component of the central Cu(II) spin, as given in eq. 3 [24].
2
2
2
2
2
Nµ g
Nµ g
1
B
Cu2,3
B
Cu1
χT = 2 ×
+
2
19
(3)
kB
3+ exp −2J k T
4kB
(
)
B
2
2
2
2
20
21
22
23
As shown in Figure 3, this model reproduces the experimental χT vs. T data very well with the
II
best set of parameters being gCu2,3= 2.16(5) (the Zeeman factor of the Cu ions in the dimer
II
units), gCu1 = 2.24(5) (the Zeeman factor of the central Cu ion) and J/k
B
= -400(3) K.
Page 13 of 53

2
2
24
25
Figure 3. Temperature dependence of the T product ( being the molar magnetic susceptibility
defined as M/H) at 1 T for 1·2H O. The solid line is the best fit obtained using the isotropic
2
2
2
2
26
27
28
29
2
dinuclear S = ½ Heisenberg model described in the text. Inset: Field dependence of the
magnetization at 1.8, 3, 5 and 7 K plotted as M vs. H/T. The solid lines are the best fits obtained
with the S = ½ Brillouin function.
2
2
2
2
2
2
2
2
2
30
31
32
33
34
35
36
37
38
T
The sign of the magnetic interactions implies that the two dinuclear Cu units possess an S = 0
spin ground state. It is worth mentioning that this fit, with a single intramolecular magnetic
interaction (the interaction between the external and central Cu(II) centers being negligible),
works remarkably well and therefore it is not reasonable to add into the model the second (much
II
weaker) intra-molecular magnetic interaction involving the central Cu ion without facing over
parametrization and multiple solutions. The field dependence of the magnetization in the 1.8-8 K
range was also measured. These data shows that the magnetization at 1.8 K under 7 T is
II
saturated at 1.16 µ
B
, as expected for one isolated S = ½ spin born by the central Cu ion with a g
factor higher than 2. The M vs H/T data can be fitted relatively well to an S = ½ Brillouin
Page 14 of 53

2
2
2
2
2
39
40
41
42
43
function with a g value of 2.30(5), corresponding to the gCu1 value obtained from the χΤ vs T
data.
4. Conclusion. In summary, a new pentanuclear {Cu
5
} complex, 1, has been synthesized by the
bpmp Schiff base ligand. This
combined action of AcO and HO anions, together with the H
3
2
2
2
2
2
2
2
2
2
2
2
2
2
44
45
46
47
48
49
50
51
52
53
54
55
56
aggregate possesses a geometry that can be described as double defective cubanes sharing a
central Cu(II) vertex that is stabilized by a set of bridging acetates in µ1,1 and µ1,1,3-modes, two
3
hydroxides in the µ -mode and phenoxido groups in a normal two centered bridging mode. These
bridges mediate within the pentanuclear complex 1, dominating antiferromagnetic interactions,
inducing an S
T
= ½ spin ground state. This work emphasizes the role of acetate ligands for the
-
self-assembly of two H
2
bpmp ligated {Cu
2
} fragments, which are responsible for the trapping of
2
+
the central Cu ion.
Acknowledgements. A.K.G. is thankful to the Council of Scientific and Industrial Research,
New Delhi, India for financial support. C.M. acknowledges the Institut Universitaire de France
(IUF) for financial support. R.C. and C.M. acknowledge the University of Bordeaux, Région
Aquitaine, GIS Advanced Materials in Aquitaine (COMET Project) and the CNRS for financial
support.
2
2
2
2
57
58
59
60
Appendix A. Supporting information. CCDC 832928 contains the supplementary
2
crystallographic data for 1·2H O. The data can be obtained free of charge from
www.ccdc.cam.ac.uk/conts/retrieving.html or from the Cambridge Crystallographic Data Centre,
12 Union Road, Cambridge CB2 1EZ, U.K.; fax, +44-1223/336-033; e-mail,
Page 15 of 53

2
2
61
62
deposit@ccdc.cam.ac.uk. Supplementary data associated with this article can be found, in the
online version.
2
2
63
64 References
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
[1] E. C. Yang, D. Ding, Z. Y. Liu, Y. L. Yang, X. J. Zhao, Cryst. Growth Des. 12 (2012) 1185-
1192.
[2] E. E. Moushi, C. Lampropoulos, W. Wernsdorfer, V. Nastopoulos, G. Christou, A. J.
Tasiopoulos, J. Am. Chem. Soc.132 (2010) 16146-16155.
[3] R. E. P. Winpenny, J. Chem. Soc., Dalton Trans. (2002) 1-10.
[4] E. I. Solomon, U. M. Sundaram, T. E. Machonkin, Chem. Rev. 96 (1996) 2563-2606.
[5] M. Alcalde, J. Polaina, A.P. MacCabe (eds.), Industrial Enzymes. 2007, pp. 461-476.
[6] M. Kumar, N. A. Dixon, A. C. Merkle, M. Zeller, N. Lehnert, E. T. Papish, Inorg. Chem. 51
(2012) 7004-7006.
[7] X. M. Zhang, J. Lv, F. Ji, H. S. Wu, H. Jiao, P. v. R. Schleyer, J. Am. Chem. Soc. 133 (2011)
4788-4790.
[8] S. Ali, C. A. Muryn, F. Tuna, R. E. P. Winpenny, Dalton Trans. 39 (2010) 124-131.
[9] Y. Ma, Y. Q. Wen, J. Y. Zhang, E. Q. Gao, C. M. Liu, Dalton Trans. 39 (2010) 1846-1854.
[10] (a) S. Majumder, S. Sarkar, S. Sasmal, E. C. Sañudo, S. Mohanta, Inorg. Chem. 50 (2011)
7540-7554. (b) K. Dhara, J. Ratha, M. Manassero, X-Y. Wang, S. Gao, P. Banerjee, J. Inorg.
Biochem. 101 (2007) 95-103. (c) C. P. Pradeep, S. Supriya, P. S. Zacharias, S. K. Das.
Polyhedron. 25 (2006) 3588-3592. (d) Z-B. Han, G-X. Zhang, M-H. Zeng, D-Q. Yuan, Q-R.
Fang, J-R. Li, J. Ribas, H-C. Zhou. Inorg. Chem. 49 (2010) 769-771.
Page 16 of 53

2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
00
01
02
03
04
[11] S. K. Mandal, K. Nag, J. Chem. Soc., Dalton. Trans. (1984) 2141-2149.
[12] A. Asokan, B. Varghese, P. T. Manoharan, Inorg. Chem. 38 (1999) 4393-4399.
[13] M. Sarkar, R. Clérac, C. Mathonière, N. G. R. Hearns, V. Bertolasi, D. Ray, Inorg. Chem.
49 (2010) 6575-6585.
[14] M. Sarkar, R. Clérac, C. Mathonière, N. G. R. Hearns, V. Bertolasi, D. Ray, Inorg. Chem.
50 (2011) 3922-3933.
[15] R. R. Gagne, C. L. Spiro, T. J. Smith, C. A. Hamann, W. R. Thies, A. K. Shiemke, J. Am.
Chem. Soc. 103 (1981) 4073-4081.
[16] G. M. Sheldrick, SHELX-97, Program for Crystal Structure and Refinement, University of
Göttingen, Germany, 1997.
[17] A. Sarkar, A. K. Ghosh, V. Bertolasi, D. Ray, Dalton Trans. 41 (2012) 1889-1895.
[18] W. A. Addison, T. N. Rao, J. Reedijk, J. V. Rijn, G. C. Verschoor, J. Chem., Soc. Dalton
Trans. (1984) 1349-1356.
[19] (a) Z. Johan, J. H. Novakit, Chem. der. Erde. 20 (1958) 49-50.(b) D. Zhang, H. Berger, R.
Kremer, D. Wulferding, P. Lemmens, M. Johnsson, Inorg. Chem. 49 (2010) 9683-9688.
[20] A. Escuer, G. Vlahopoulou, S. P. Perlepes, F. A. Mautner, Inorg. Chem. 50 (2011) 2468-
2478.
[21] L. Lei, K. D. Karlin, S. E. Rokita, J. Am. Chem. Soc.127 (2005) 520-521.
[22] J. H. van Vleck, The Theory of Electric and Magnetic Susceptibility; Oxford University
Press, 1932.
[23] K. Kambe, J. Phys. Soc. Jpn. 5 (1950) 48.
[24] C. J. O’Connor, Prog. Inorg. Chem. 29 (1982) 203-283.
Page 17 of 53

3
3
3
05 Graphical Abstract
06 Self-Assembly of a Pentanuclear {Cu } Complex Resulting from the Trapping
5
2
+
07 of a Cu Ion by Two {Cu } Building Units
2
[
a]
[b,c]
[d,e]
[a]
3
3
08
09
Aloke Kumar Ghosh, Rodolphe Clérac, Corine Mathonière, and Debashis Ray*
3
3
3
10
11
12
The binding of acetate anions in three different modes along with water derived µ
3
-hydroxido
groups dictate the stabilization of a pentanuclear copper(II) complex resulting from the self-
2
assembly of two dinuclear {Cu } units around a central copper ion.
3
3
13
14
Page 18 of 53

3
3
15
16 Supporting Information
3
3
17 Self-Assembly of a Pentanuclear {Cu } Complex Resulting from the Trapping
5
2
+
18 of a Cu Ion by Two {Cu } Building Units
2
3
3
3
3
3
3
3
3
19
[
a]
[b,c]
[d,e]
[a]
20
21
22
23
24
25
26
Aloke Kumar Ghosh, Rodolphe Clérac, Corine Mathonière and Debashis Ray*
[a]
Department of Chemistry, Indian Institute of Technology, Kharagpur 721 302, India
Fax: (+91) 3222-82252; Tel: (+91) 3222-283324; E-mail: dray@chem.iitkgp.ernet.in
[b]
[c]
[d]
[e]
CNRS, CRPP, UPR 8641, Pessac, F-33600, France.
Univ. Bordeaux, CRPP, UPR 8641, Pessac, F-33600, France.
CNRS, UPR 9048, ICMCB, Pessac, F-33600, France
Univ. Bordeaux, ICMCB, UPR 9048, Pessac, F-33600, France.
Page 19 of 53

3
3
27
28
3
Scheme S1. Different binding modes of H bpmp
3
3
29
30
3
Scheme S2. Synthesis of the H bpmp ligand.
3
31
3
32
[
1]
3
3
33
34
Figure S1. DIAMOND view of 1·2H
2
O showing the ligand with different colors; red, O; blue,
N; brown, Cu; pink, H
2
bpmp (the thermal ellipsoids are shown at 40% probability).
Page 20 of 53

3
35
3
3
36
37
Figure S2.View of the atom connectivity within the [Cu
5
] complex with three different types of
acetato binding modes in 1·2H O. Color code: brown, Cu; blue, N; red, O; black, C.
2
3
3
38
39
3
40
3
3
41
42
2
FigureS3. Molecular view of 1·2H O with the highlighted octahedral environment of the central
copper atom.
3
43
Page 21 of 53

O3
N1
O8*
N2*
7
9.85
2
.3760
Cu2
O6*
O4
Cu3*
O2 1.982 Cu1
O1
O1*
Cu3
O4*
O6
Cu2*
2
.625
N1*
N2
O8
O3*
3
44
3
3
3
45
46
47
2
Figure S4. Atom connectivity of the pentanuclear Cu(II) core in 1·2H O with the relevant inter-
atomic bond distances (Å) and angles (º). Atoms labelled with a ‘*’ are generated from the parent
atoms through the symmetry operation (-x, 1-y,- z).
3
48
3
3
49
50
3
3
51
52
Figure S5. Geometry of the coordination sphere around the crystallographically independent
copper(II) ions in complex 1.
Page 22 of 53

3
53
3
54
3
3
3
3
55
56
57
58
Figure S6. Ball and stick style representations of 1·2H
2
O emphasizing the intra- and inter-
] complex (top)
molecular hydrogen bonds (labelled as pink lines) established around the [Cu
5
and in the three-dimensional network viewed along the b axis (labelled in dotted green lines)
(bottom).
3
59
3
60
Page 23 of 53

3
61
Figure S7. Different coordinating modes of the acetate ligands in 1.
3
62
3
3
63
64
Figure S8. Vertex shared dicubane structure showing three colored (blue, green and pink)
tetragonal faces of two partial cubanes.
3
3
65
66
[1] W. T. Pennington, Applied crystallography. 1999. 32. 1028.
Page 24 of 53

3
3
67 Graphical Abstract
68
3
3
69 Self-Assembly of a Pentanuclear {Cu } Complex Resulting from the Trapping
5
2
+
70 of a Cu Ion by Two {Cu } Building Units
2
3
3
3
71
72
73
Aloke Kumar Ghosh, Rodolphe Clérac, Corine Mathonière and Debashis Ray*
3
3
3
74
75
76
3
The binding of acetate anions in three different modes along with water derived µ -hydroxido
groups dictate the stabilization of a pentanuclear copper(II) complex resulting from the self-
2
assembly of two dinuclear {Cu } units around a central copper ion.
3
3
77
78
3
79
Page 25 of 53

3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
00
01
02
03
04
data_publication_text
_publ_requested_journal
_publ_contact_author_name
_publ_contact_author_address
;Prof. Debashis Ray
Polyhedron
"'Prof. Debashis Ray'"
Department of Chemistry
Indian Institute of Technology
Kharagpur‐721302
India
;
_publ_contact_author_email
_publ_contact_author_phone
_publ_contact_author_fax
loop_
dray@chem.iitkgp.ernet.in
03222‐283324
03222‐255303
_publ_author_name
_publ_author_address
"'Prof. Debashis Ray', Aloke Kumar Ghosh"
;Prof. Debashis Ray
Department of Chemistry
Indian Institute of Technology
Kharagpur‐721302
India
;
Page 27 of 53

4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
05
06
07
08
09
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
data_platon
_audit_creation_method
_chemical_name_systematic
;
SHELXL‐97
?
;
_chemical_name_common
_chemical_melting_point
_chemical_formula_moiety
_chemical_formula_sum
'C42 H66 Cu5 N4 O22'
_chemical_formula_weight
?
?
'C42 H62 Cu5 N4 O20, 2(H2 O)'
1296.74
loop_
_atom_type_symbol
_atom_type_description
_atom_type_scat_dispersion_real
_atom_type_scat_dispersion_imag
_atom_type_scat_source
'C' 'C' 0.0030 0.0020
'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4'
'H' 'H' 0.0000 0.0000
'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4'
Page 28 of 53

430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
'Cu' 'Cu' 0.3200 1.2650
'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4'
'N' 'N' 0.0060 0.0030
'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4'
'O' 'O' 0.0110 0.0060
'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4'
_symmetry_cell_setting
'Monoclinic'
_symmetry_space_group_name_H‐M 'P 21/c'
loop_
_symmetry_equiv_pos_as_xyz
'x, y, z'
'‐x, y+1/2, ‐z+1/2'
'‐x, ‐y, ‐z'
'x, ‐y‐1/2, z‐1/2'
_cell_length_a
11.4604(7)
13.7598(8)
17.3334(10)
90.00
_cell_length_b
_cell_length_c
_cell_angle_alpha
_cell_angle_beta
_cell_angle_gamma
_cell_volume
103.317(2)
90.00
2659.9(3)
2
_cell_formula_units_Z
Page 29 of 53

4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
_cell_measurement_temperature 293(2)
_cell_measurement_reflns_used
_cell_measurement_theta_min
_cell_measurement_theta_max
?
?
?
_exptl_crystal_description
_exptl_crystal_colour
'block'
'green'
_exptl_crystal_size_max
_exptl_crystal_size_mid
_exptl_crystal_size_min
_exptl_crystal_density_meas
0.36
0.25
0.15
?
_exptl_crystal_density_diffrn 1.618
_exptl_crystal_density_method 'not measured'
_exptl_crystal_F_000
1334
_exptl_absorpt_coefficient_mu 2.047
_exptl_absorpt_correction_type 'empirical'
_exptl_absorpt_correction_T_min 0.547
_exptl_absorpt_correction_T_max 0.736
_exptl_absorpt_process_details ?
_exptl_special_details
;
?
;
Page 30 of 53