A novel high-spin tridecanuclear NiII cluster with an azido-bridged core exhibiting disk-like topology

Article abstract of DOI:10.1039/c2cc16221k

A high-spin tridecanuclear Ni^II cluster, [Ni^II ₁₃(N₃)₁₈(dpo)₄(Hdpo) ₂(H₂hpo)₄(H₂O)(MeOH)] [Ni ^II₁₃(N₃)₁₈(dpo)₄(Hdpo) ₂(H₂hpo)₄(H₂O)₂] (1) (Hdpo = 1-(dimethylamino)propan-2-one oxime and H₂hpo = 1-(hydroxyamino)propan-2-one oxime) with a purely azido-bridged core, is reported with dominant ferromagnetic coupling between Ni^II ions. The latter molecule exhibits a unique planar core topology with the largest N ₃^-:Ni^II ratio reported to date. The Royal Society of Chemistry 2012.

Full text of DOI:10.1039/c2cc16221k

View Article Online / Journal Homepage / Table of Contents for this issue
Dynamic Article Links
ChemComm
Cite this: Chem. Commun., 2012, 48, 1287–1289
www.rsc.org/chemcomm
COMMUNICATION
II
A novel high-spin tridecanuclear Ni cluster with an azido-bridged core
exhibiting disk-like topologyw
a
a
a
a
a
Gabriel Brunet, Fatemah Habib, Cyril Cook, Thushan Pathmalingam, Francis Loiseau,
a
a
ab
ab
Ilia Korobkov, Tara J. Burchell, Andre M. Beauchemin and Muralee Murugesu*
´
Received 6th October 2011, Accepted 29th November 2011
DOI: 10.1039/c2cc16221k
II
A high-spin tridecanuclear Ni cluster, [Ni (N ) (dpo) (Hdpo) -
II
1
II
II
m -OH by m -N in high nuclearity clusters of Co , Ni and
II
3
3 18
4
2
4
4
3
II
(
H
2
hpo)
O) ] (1) (Hdpo = 1-(dimethylamino)propan-2-one oxime and
hpo = 1-(hydroxyamino)propan-2-one oxime) with a purely
4
(H
2
O)(MeOH)]
[Ni 13(N
3
)
18(dpo)
4
(Hdpo)
2
(H
2
hpo)
4
-
Fe resulted in ferromagnetic coupling, however no purely
azido-bridged complex has been reported. Herein, we describe
II
a tridecanuclear Ni cluster, 1, exhibiting a heptanuclear
(H
2
2
H
2
ꢀ
II
azido-bridged core, is reported with dominant ferromagnetic coupling
II
between Ni ions. The latter molecule exhibits a unique planar core
disk-like core and the highest N
3
: Ni ratio reported to date.z
To the best of our knowledge, compound 1 is an unprecedented
II
ꢀ
II
: Ni ratio reported to date.
topology with the largest N
3
example of a purely m
with an N
3
-N
3
bridged planar core for a Ni cluster
ꢀ
3
II
: Ni ratio of 1.4 : 1. In addition to azide-based
ligands, our synthetic strategy focuses on employing chelating
ligands which arrest the formation of coordination networks/
sheets and form well-isolated complexes while maximizing
intramolecular ferromagnetic interactions.
Organizing building blocks on a molecular scale has been a
challenging task which led to the investigation of self-assembled
1
molecular precursors. In such molecules, controlling the inter-
actions between metal ions provides a way to control the overall
spin ground state of a complex. This consequently can have
significant implications on its physical properties such as
The Hdpo chelating ligand was synthesized through Cope-type
hydroamination of 3-(dimethylamino)-1-propyne (dmp) with
aqueous hydroxylamine in n-propanol (eqn (1)). Interestingly,
2
Single-Molecule Magnet (SMM) behaviour. Transition metal
complex 1 also shows the incorporation of a new ligand (H
which is accessed in situ during the crystallization process and
results from partial conversion of Hdpo to H hpo (eqn (2)).
3
hpo)
complexes with characteristic oxido/hydroxido-bridged core
structures are relatively well-known for exhibiting magnetic
interactions that are ferro- or antiferromagnetic in nature
3
2d,3
A detailed proposed mechanism of this conversion is described
without definite predictability.
Using chelating ligands to
in Scheme S1 (ESIw).
encapsulate a portion of metal oxido/hydroxido layers under
basic solvolytic conditions has been a method of choice in
nanoscale cluster chemistry where several factors can influence
the nature of the interactions such as bridging ligands as well
ð1Þ
2
d,3c,4
as their bridging modes, distances and angles.
In order to
exert a degree of control, oxido/hydroxido bridging moieties
can be replaced by azide groups where the type of magnetic
5
interaction promoted depends highly on the bridging mode. It
has been well-documented that end-on (EO) and end-to-end
(
EE) bridging modes promote ferromagnetic and antiferro-
6
ð2Þ
magnetic interactions, respectively. Therefore, azide groups
provide a unique way of isolating similar structural cores with
The reaction of NiCl ꢁ6H O (0.059 g, 0.25 mmol) with Hdpo
2
2
7
(0.029 g, 0.25 mmol) and sodium azide (0.033 g, 0.50 mmol) in
predominantly ferromagnetic coupling between metal centres.
1
0 mL of MeOH resulted in a clear green solution from which
Recently, several attempts have been made towards this goal by
1f,8
Perlepes and co-workers
II
dark-brown hexagonal crystals of [Ni 13(N
)
18(dpo)
4
(Hdpo)
2
-
-
who demonstrated that replacing
3
II
O)(MeOH)] [Ni 13(N
(
(
H
H
2
hpo)
O)
4
(H
2
3
)
18(dpo)
(Hdpo) (H hpo)
4 2
2
4
2
2
], 1A and 1B, were isolated (full experimental details
a
Department of Chemistry, University of Ottawa, 10 Marie-Curie,
Ottawa, ON K1N6N5, Canada. E-mail: m.murugesu@uottawa.ca;
Fax: +1 613 562 5170; Tel: +1 613 562 5800-2733
Centre for Catalysis Research and Innovation, 30 Marie-Curie,
Ottawa, ON K1N6N5, Canada
w Electronic supplementary information (ESI) available: Experimental
and structural details, bond distances, angles and torsion angles,
ligand NMR spectra. CCDC 847307. For ESI and crystallographic
data in CIF or other electronic format see DOI: 10.1039/c2cc16221k
are included in the ESIw, caution should be taken during
synthesis and handling as azide salts and related complexes
can be potentially explosive). It is noteworthy that the single-
crystal X-ray crystallography (see Table S1 (ESIw) for parameters)
revealed two clusters of {Ni } in the same unit cell which differ
b
13
only by one terminal ligand. In molecule A, terminal H O and
2
MeOH are coordinated to Ni(6) and Ni(8), respectively, while
This journal is c The Royal Society of Chemistry 2012
Chem. Commun., 2012, 48, 1287–1289 1287

View Article Online
2
in molecule B (Fig. S2, ESIw), terminal H O molecules are
II
coordinated to the corresponding Ni centres, Ni(19) and Ni(21).
Complex 1 consists of both units A and B differing by one
terminal solvent molecule which are arranged in layers that
correspond to an ABA ordering. Although the packing
arrangement along the c-axis shows overlapping A and B
units within the layer, they are in fact positioned one in front
of the other. This can be seen clearly in the packing diagram
along the b-axis (Fig. S5, ESIw) with the shortest intra-layer
II
II
˚
Ni –Ni distance of 8.71 A between Ni(6) and Ni(20). Moreover,
the layers are arranged in an anti-parallel fashion permitting the
closest packing possible with the shortest inter-layer distance of
˚
8
.88 A between Ni(5) and Ni(21). Overall complex 1 consists of
ꢀ
II
.4 : 1 N3 : Ni ratio which makes this system potentially
1
attractive for high-energy materials study. The initial ‘‘shock test’’
reveals that the latter complex is rather stable. Further studies are
currently underway to examine the energetic content and methods
of release for this complex. The structure of 1A consists of thirteen
II
octahedral Ni ions arranged in a disk-like fashion (Fig. 1, top,
with a fully labelled core structure in Fig. S3, ESIw). The
coordination environment of the central Ni(7) atom consists of
Fig. 2 Packing of 1 along the c-axis in an ABA arrangement in both
a- and b-directions. Complex 1 consists of both units A and B which
differ by one terminal coordinated solvent molecule.
six N atoms exclusively from m
3
-N
Ni ions coordinate to both N- and O-based ligands. Complex
A is rich in azide groups which display electronic versatility
3
groups while the remaining
II
II
central core consists of seven Ni ions bridged solely via six
1
by bridging in two different modes: EO and EE. The planar
m
3
-N
moieties which alternate above and below the mean
3
plane (Fig. 1, bottom). The outer shell consisting of six
II
Ni centres is linked to the planar core through m
3
-N
3
, m-N
3
as well as oxime-based ligands which are highlighted in Fig. 1
in orange and black. Ni(6) and Ni(8) are connected to the
ꢀ
central core exclusively through N
3
moieties resulting in their
II
orientation within the plane. The remaining four Ni centres
are slightly out of the mean plane as illustrated in Fig. 2 due to
twisting of the oxime bridges. Both Ni(12) and Ni(1) are above
˚
the plane by 0.43 and 0.42 A, respectively, while Ni(13) and
˚
Ni(2) are below the plane by 0.44 and 0.42 A, respectively.
Selected bond distances, angles and torsion angles are listed in
Table S2 (ESIw). Within the outer shell, Ni(1) and Ni(2) as well
ꢀ
ꢀ
as Ni(12) and Ni(13) are bridged by N
3
in an EE fashion.
ꢀ
Bidentate Hdpo as well as tridentate dpo and H
2
hpo oxime-
based ligands serve as capping agents in 1A forming five-
membered rings with peripheral Ni atoms resulting in isolated
molecular entities. Additionally, compound 1A exhibits near
II
symmetry through the central Ni ion as well as the mean
C
2
plane of the core. Packing arrangements along the a-, b- and c-axes
are shown in Fig. S4 and S5 (ESIw), and Fig. 2, respectively.
Magnetic studies were performed on a polycrystalline sample
of 1. The direct current (dc) magnetic susceptibility under an
applied dc field of 1000 Oe is plotted as wT vs. T and shown in
3
ꢀ1
ꢀ1
Fig. 3. The room temperature wT value of 18.86 cm K mol is
slightly higher than the expected value of 13.00 cm K mol for
3
II
thirteen non-interacting Ni ions with g = 2.0. As the
temperature decreases, the wT value continuously increases
reaching a maximum of 58.27 cm K mol at 5.5 K then
3
ꢀ1
3
ꢀ1
drops to 56.36 cm K mol at 2.5 K. The increase of wT with
decreasing temperatures is indicative of strong ferromagnetic
coupling between the metal centres which is evident even at
room temperature since the wT value is slightly higher than the
aforementioned theoretical value. The observed ferromagnetic
Fig. 1 Top: partially labelled tridecanuclear structure of complex 1A.
ꢀ
II
shown in black. Colour code: green (Ni ), blue (N), red (O). Bottom:
ꢀ
Hdpo and dpo ligands are shown in orange while H
2
hpo ligands are
side view of 1A with the mean plane shown in dark green.
coupling is induced by the EO-N
3
bridges which tend to
1
288 Chem. Commun., 2012, 48, 1287–1289
This journal is c The Royal Society of Chemistry 2012

View Article Online
energy triggered via an applied magnetic field. To achieve such
goals we are currently pursuing the isolation of high-energy
materials with controllable magnetic properties.
We thank the University of Ottawa, the Canada Foundation
for Innovation (CFI), FFCR and NSERC (Discovery and RTI
grants) for financial support.
Notes and References
z Crystal data for 1: C85
190
H N148Ni26O34, M = 5356.31, green block,
˚
monoclinic, P2
1
, a = 19.046(3), b =29.147(6), c = 23.518(4) A, a =
3
˚
9
2
0.001, b = 100.48(1)1, g = 90.001, V = 12838(4) A , Z = 2, T =
00(2) K, l = 0.71073 A, ymax = 21.971, 78 643 reflections collected of
= 0.0763 [based on I > 2s(I)],
˚
which 9914 were independent, R
wR = 0.2366 (based on F and all data), GOF on F = 1.041. CCDC
1
2
2
2
8
47307.
1
(a) K. E. Vostrikova, D. Luneau, W. Wernsdorfer, P. Rey and
M. Verdaguer, J. Am. Chem. Soc., 2000, 122, 718; (b) G. Schmid,
¨
M. Baumle, M. Geerkens, I. Heim, C. Osemann and T. Sawitowski,
Fig. 3 Temperature dependence of the magnetic susceptibility for
under an applied dc field of 1000 Oe. Inset: M vs. H/T plot showing
1
Chem. Soc. Rev., 1999, 28, 179; (c) O. M. Yaghi, M. O’Keeffe,
N. W. Ockwig, H. K. Chae, M. Eddaoudi and J. Kim, Nature, 2003,
423, 705; (d) G. E. Kostakis and A. K. Powell, Coord. Chem. Rev.,
non-saturation and non-superposition of the magnetization curves at
different temperatures.
2
(
009, 253, 2686; (e) M. Murrie, Chem. Soc. Rev., 2010, 39, 1986;
f) C. Papatriantafyllopoulou, E. Diamantopoulou, A. Terzis, N. Lalioti,
promote magnetic-orbital orthogonality due to sharp bridging
V. Tangoulis and S. P. Perlepes, Inorg. Chem. Commun., 2008, 11, 454.
(a) D. Gatteschi, A. Caneschi, L. Pardi and R. Sessoli, Science,
1994, 265, 1054; (b) T. C. Stamatatos, K. A. Abboud,
W. Wernsdorfer and G. Christou, Angew. Chem., Int. Ed., 2007,
5b,c,6b
angles.
ground state of 9 r S
Fig. 3, inset) shows non-saturation as well as non-superposition
The maximum value of wT indicates a large spin
2
T
r 10 for g = 2. The M vs. H/T plot
(
4
3
6, 884; (c) L. M. C. Beltran and J. R. Long, Acc. Chem. Res., 2005,
8, 325; (d) M. Murugesu, R. Clerac, W. Wernsdorfer, C. E. Anson
and A. K. Powell, Angew. Chem., Int. Ed., 2005, 44, 6678.
of the magnetization curves at low temperatures (2.5 K) and high
applied magnetic fields (up to 7 T). This indicates the presence of
low-lying excited states which significantly complicate the
calculations of the spin ground state for 1. Additionally, in
order to obtain a reasonable fit of the magnetic susceptibility,
all six different magnetic exchange pathways (Fig. S6, ESIw)
must be taken into consideration rendering the Hamiltonian
equation quite complicated. The value of M at 2.5 K and 7 T
´
3 (a) D. Foguet-Albiol, K. A. Abboud and G. Christou, Chem.
Commun., 2005, 4282; (b) N. Hoshino, A. M. Ako, A. K. Powell
and H. Oshio, Inorg. Chem., 2009, 48, 3396; (c) P. King,
W. Wernsdorfer, K. A. Abboud and G. Christou, Inorg. Chem.,
2004, 43, 7315; (d) D. J. Price, S. R. Batten, B. Moubaraki and
K. S. Murray, Chem. Commun., 2002, 762; (e) E. K. Brechin,
S. G. Harris, A. Harrison, S. Parsons, A. G. Whittaker and R. E. P.
Winpenny, Chem. Commun., 1997, 653; (f) J. C. Goodwin, S. J. Teat
and S. L. Heath, Angew. Chem., Int. Ed., 2004, 43, 4037;
(g) A. Ferguson, A. Parkin, J. Sanchez-Benitez, K. Kamenev,
W. Wernsdorfer and M. Murrie, Chem. Commun., 2007, 3473;
of 17.76 m
Moreover, the presence of two types of {Ni13} complexes
1A and 1B) further complicates the detailed analysis of the
B
is in good agreement with g E 2 and 9 r S r 10.
T
(
(h) E. Rather, J. T. Gatlin, P. G. Nixon, T. Tsukamoto, V. Kravtsov
exact spin ground state. Alternating current (ac) magnetic
measurements were performed on 1 in order to probe other
potential properties such as slow magnetic relaxation characteristic
of SMM behaviour. However, no out-of-phase, frequency-
dependent signal was detected even at low temperatures (down
to 2.5 K) indicating the absence of such SMM behaviour.
and D. W. Johnson, J. Am. Chem. Soc., 2005, 127, 3242;
(i) J. C. Goodwin, R. Sessoli, D. Gatteschi, W. Wernsdorfer,
A. K. Powell and S. L. Heath, J. Chem. Soc., Dalton Trans., 2000, 1835.
(a) C. J. Milios, A. Vinslava, P. A. Wood, S. Parsons,
W. Wernsdorfer, G. Christou, S. P. Perlepes and E. K. Brechin,
J. Am. Chem. Soc., 2007, 129, 2754; (b) S. Mukherjee, R. Bagai,
K. A. Abboud and G. Christou, Inorg. Chem., 2011, 50, 3849.
4
5
(a) A. Escuer and G. Aromı, Eur. J. Inorg. Chem., 2006, 4721;
´
In conclusion, an in-depth study of a novel, high-spin
II
Ni } cluster has been reported focusing on its unique
(b) Y. Z. Zhang, H. Y. Wei, F. Pan, Z. M. Wang, Z. D. Chen and
S. Gao, Angew. Chem., Int. Ed., 2005, 44, 5841; (c) A. M. Ako,
I. J. Hewitt, V. Mereacre, R. Clerac, W. Wernsdorfer, C. E. Anson
´
and A. K. Powell, Angew. Chem., Int. Ed., 2006, 45, 4926.
(a) Y. Z. Zhang, W. Wernsdorfer, F. Pan, Z. M. Wang and S. Gao,
Chem. Commun., 2006, 3302; (b) J. Ribas, A. Escuer, M. Monfort,
{
1
3
architectural features as well as magnetic properties. In recent
years, complexes with planar oxido/hydroxido-bridged core
structures have been investigated where the prediction of
ferromagnetic interactions in such systems was not possible.
We were able to alleviate this problem by promoting predo-
minantly EO azido bridges between metal centres thus leading
to dominant ferromagnetic interactions. To our knowledge,
this is the first transition metal complex containing a single
bridging mode, m -N , within the core as well as m-N and
6
7
R. Vicente, R. Corte
1999, 193–195, 1027.
(a) X. T. Wang, B. W. Wang, Z. M. Wang, W. Zhang and S. Gao,
Inorg. Chim. Acta, 2008, 361, 3895; (b) G. Aromı, S. Parsons,
´
s, L. Lezama and T. Rojo, Coord. Chem. Rev.,
´
W. Wernsdorfer, E. K. Brechin and E. J. L. McInnes, Chem.
Commun., 2005, 5038; (c) M. L. Tong, M. Monfort,
J. M. Clemente-Juan, X. M. Chen, X. H. Bu, M. Ohba and
S. Kitagawa, Chem. Commun., 2005, 233.
8 (a) G. S. Papaefstathiou, S. P. Perlepes, A. Escuer, R. Vincente,
M. Font-Bardia and X. Solans, Angew. Chem., Int. Ed., 2001,
40, 884; (b) A. K. Boudalis, Y. Sanakis, J. M. Clemente-Juan,
B. Donnadieu, V. Nastopoulos, A. Mari, Y. Coppel,
J.-P. Tuchagues and S. P. Perlepes, Chem.–Eur. J., 2008, 14, 2514;
3
3
3
ꢀ
3
II
m -N in the outer shell resulting in the highest N : Ni ratio
3
3
ꢀ
reported to date of 1.4 : 1. Complexes with such a high N3 to
metal ratio provide a route to novel high-energy materials, where
energy storage and release could potentially be controlled by
molecular architectures. Extension of this synthetic methodology
may provide new avenues for molecular nanoscale materials with
multiple applications. One of which could be the release of
(
c) C. Papatriantafyllopoulou, E. Diamantopoulou, A. Terzis,
V. Tangoulis, N. Lalioti and S. P. Perlepes, Polyhedron, 2009,
28, 1903.
This journal is c The Royal Society of Chemistry 2012
Chem. Commun., 2012, 48, 1287–1289 1289