Synthesis and Structural Characterization of Cationic 5-Hydroxy-1,3- diketonate Stabilized Dinuclear Complexes and Tetranuclear Lanthanoid Clusters

Article abstract of DOI:10.1021/ic1001732

5-Hydroxy-1,3-diketonate ligands have been found to stabilize dimeric complexes and tetrameric lanthanoid clusters dependent on the degree of steric bulk provided by the presence or absence of a methoxy group. Treatment of (R/S,Z)-1'-hydroxy-3-(hydroxy(phenyl)methylene)bi(cyclopentan)-2-one (Hhpb) and the p-methoxyphenyl derivative (Hhmb) with [LnCl₂(H ₂O)₆]Cl yields clusters of composition [Ln ₄(Cl)₂(O)(hpb)₆]Cl₂ (Ln = Nd (1), Ho (2), Tb (3), and Er (4)) and [Ln₂(hmb)₅]Cl (Ln = La (5), Nd (6), Tb (7), Dy (8), and Er (9)). Single crystal X-ray analysis of the tetranuclear cluster has revealed the lanthanoid core to be in a tetrahedral arrangement around a central μ₄-oxygen, bridged by symmetrical chlorides and shrouded in six bridging hpb ligands. The dimeric complexes are stabilized by three bridging and two terminal hmb ligands. In each instance, double or single cationic charges respectively are balanced by chloride anions.

Full text of DOI:10.1021/ic1001732

5016 Inorg. Chem. 2010, 49, 5016–5024
DOI: 10.1021/ic1001732
Synthesis and Structural Characterization of Cationic 5-Hydroxy-1,3-diketonate
Stabilized Dinuclear Complexes and Tetranuclear Lanthanoid Clusters
Philip C. Andrews, William J. Gee, Peter C. Junk,* and Jonathan G. MacLellan
School of Chemistry, Monash University, Victoria, Clayton 3800, Australia
Received January 28, 2010
5-Hydroxy-1,3-diketonate ligands have been found to stabilize dimeric complexes and tetrameric lanthanoid clusters
dependent on the degree of steric bulk provided by the presence or absence of a methoxy group. Treatment of (R/S,Z)-
10-hydroxy-3-(hydroxy(phenyl)methylene)bi(cyclopentan)-2-one (Hhpb) and the p-methoxyphenyl derivative (Hhmb) with
[LnCl2(H2O)6]Cl yields clusters of composition [Ln4(Cl)2(O)(hpb)6]Cl2 (Ln = Nd (1), Ho (2), Tb (3), and Er (4)) and
[Ln2(hmb)5]Cl (Ln = La (5), Nd (6), Tb (7), Dy (8), and Er (9)). Single crystal X-ray analysis of the tetranuclear cluster has
revealed the lanthanoid core to be in a tetrahedral arrangement around a central μ4-oxygen, bridged by symmetrical
chlorides and shrouded in six bridging hpb ligands. The dimeric complexes are stabilized by three bridging and two terminal
hmb ligands. In each instance, double or single cationic charges respectively are balanced by chloride anions.
Introduction
includes dinuclear,3 trinuclear,4 tetranuclear,5-10 penta-
nuclear,7,10-13 hexanuclear,14 octanuclear,11 nonanuclear,11,15-19
and dodecanuclear20 clusters. Of these cluster motifs, the
majority are neutral species, the exceptions being (i) nona-
nuclear compounds, which may be neutral,11 or either
positively17-19 or negatively charged,15,16 and (ii) a serendi-
pitous cationic trinuclear holmium complex.4
The chemistry of lanthanoid diketonate clusters has ex-
panded in recent years to include a diverse range of nuclea-
rities and structural motifs.1 The initial well-characterized
example of this family, an octanuclear erbium cluster, was
first reported in 1972.2 Since this time, the chemistry of
diketonate clusters has continually expanded and currently
The intrinsic luminescent,11,21-27 magnetic,12,28,29 and Le-
wis acidic properties of the lanthanoid metals means that
there is great potential for such clusters to find application
in chemical sensing, biological chemistry, medicine, and
catalysis.7 While simple mononuclear lanthanoid com-
pounds may already be considered to be ubiquitous in these
areas, exploring the unique chemistry of the clusters and
progressing from mere possibility to actual application has
*To whom correspondence should be addressed. E-mail: peter.junk@
sci.monash.edu.au.
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M. J. Alloys Compd. 2004, 374, 382.
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M. D. J. Alloys Compd. 2006, 406, 1046.
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r
pubs.acs.org/IC
Published on Web 04/29/2010
2010 American Chemical Society

Article
Inorganic Chemistry, Vol. 49, No. 11, 2010 5017
Scheme 1.a
a Reagents and conditions: (a) THF, -78 °C, 5 min; (b) 2 equiv LiHMDS, 5 min; (c) 1 equiv cyclopentanone, -78 °CfRT, 2 h.
been relatively slow. This is because the large majority of
lanthanoid oxo/hydroxo clusters have only been prepared
and isolated serendipitously, with little design or control.
However, a substantial numberand varietyofneutralclusters
now exist that makes it possible to gain some insight and
understanding into their chemistry. In contrast, there re-
mains a paucity of information on the synthesis, isolation,
and properties of analogous charged species.
An analysis of the structural types observed for the various
clusters suggests a trend inversely linking cluster size to the
degree of hindrance offered by the ligand. As such, the
dominance of neutral clusters in the literature can be attributed
to a bias in using compact ligands with open, easily accessible
chelation regions. Such ligands, while actively aiding cluster
growth by facilitating the conversion of coordinated water
molecules to the oxo- and hydroxo- components of the metal
cage core, promote a final neutral charge on the metal oxo/
hydroxo core through the lack of steric hindrance offered by
the ligands to incoming water molecules.
Figure 1. Molecular structure of Hhpb showing hydrogen bonding
interactions between two molecules. Thermal ellipsoids are shown at
50% probability.
Tetranuclear lanthanoid clusters 1-4 were characterized by
Raman and infrared spectroscopy, elemental and thermogravi-
metric analysis, mass spectrometry, and in the case of 1, single
crystal X-ray crystallography. Dinuclear lanthanoid clusters
5-9were characterized by infrared spectroscopy, elemental and
thermogravimetric analysis, mass spectrometry, and single
crystal X-ray crystallography for 5 and 7.
It follows that stable cationic cluster species of varying
nuclearity should be accessible through opposing this trend, that
is, designing and using ligands with sufficient steric bulk and with
multiple coordination sites that allow cluster growth but would
displace coordinated water from the cluster core. The lack of
coordination of water to the metal ions and sufficient shielding of
the ligands from secondary deprotonation would ensure that the
cationic charge of the cluster core could not be completely offset.
In this paper, we now report the syntheses of two new series of
cationic lanthanoid diketonate clusters, including the synthetic
pathway to a chloride-bridged tetrahedral motif using an air- and
moisture-stable methodology. The clusters are stabilized by two
new ligands: (R/S,Z)-10-hydroxy-3-(hydroxy(phenyl)methylene)-
bi(cyclopentan)-2-one (Hhpb) and the corresponding p-methox-
yphenyl derivative (Hhmb), which give clusters of composition
[Ln4(Cl)2(O)(hpb)6]Cl2 (Ln = Nd (1), Ho (2), Tb (3), and Er
(4)) and [Ln2(hmb)5]Cl (Ln = La (5), Nd (6), Tb (7), Dy (8),
and Er (9)). The cationic nature of the clusters is a result of ligand
design, whereby coordinating hydroxy groups of the tridentate
ligands are masked by bulky cyclopentane rings which prevent
basic attack, ensuring a monoanionic charge on each ligand.
The tricyclic 5-hydroxy-1,3-diketones, Hhpb and Hhmb,
were obtained in moderate yields by a rapid one-pot synthetic
procedure and have been fully characterized using standard
spectroscopic techniques including Hhpb by single crystal X-ray
diffraction. Cluster formation was achieved by a variation of
“ligand controlled hydrolysis”,30 whereby displacement of
already present coordinated water molecules with shielding
ligands culminates in a finite number of resultant hydroxo
and oxo species capable of generating the core structure.
Results and Discussion
The 5-hydroxy-1,3-diketones used in this study were
synthesized by a rapid, one-pot reaction proceeding via
formation of a 2-benzoylcyclopentanone intermediate. The
intermediate was treated with lithium hexamethyldisilazide
(LiHMDS) and cyclopentanone (Scheme 1), yielding the
desired ligands after purification by column chromato-
graphy. Moderate yields for both ligands were obtained,
ranging from 56% for Hhpb to 63% for Hhmb.
Solution state 1H NMR analysis of Hhpb and Hhmb
determined that each primarily exists as the enol tautomer,
as identified by resonances corresponding to the enolic
proton at 14.49 and 14.64 ppm, respectively. The minor keto
tautomer was detected as a triplet at 4.25 ppm for Hhpb and a
doublet of doublets at 4.21 ppm for Hhmb corresponding to
a proton at the R position. The ratio of keto and enol
tautomerism was determined to be 1:5 and 1:2.5, respectively.
A solid state structure of Hhpb was obtained by single crystal
X-ray diffraction (Figure 1). The enol form was identified via
assignment of residual electron density to the enol proton
H(1) and the hydroxy proton H(2). Furthermore, the planar
geometry (sum of bond angles is 359.99°) around C(2)
confirms the presence of the enol tautomer. In the extended
crystal structure, two antiparallel molecules are offset such
that they link through hydrogen bonding from the hydroxy
group of one molecule to the ketone oxygen of its neighbor.
(30) Wang, R.; Liu, H.; Carducci, M. D.; Jin, T.; Zheng, C.; Zheng, Z.
Inorg. Chem. 2001, 40, 2743.

5018 Inorganic Chemistry, Vol. 49, No. 11, 2010
Andrews et al.
Table 1. Selected Bond Lengths and Angles for 1a
˚
Bond Lengths, A
Nd(1)-O(1)*
Nd(1)-O(2)
Nd(1)-O(2)*
Nd(1)-O(3)
Nd(1)-O(4)*
Nd(1)-O(5)*
Nd(1)-O(10)
Nd(1)-Cl(1)
2.353(6)
2.534(6)
2.562(6)
2.453(6)
2.396(6)
2.443(6)
2.362(4)
2.850(2)
Nd(2)-O(5)
Nd(2)-O(6)
Nd(2)-O(7)*
Nd(2)-O(8)
Nd(2)-O(8)*
Nd(2)-O(9)
Nd(2)-O(10)
Nd(2)-Cl(1)
2.432(6)
2.508(6)
2.349(6)
2.467(6)
2.544(6)
2.461(6)
2.366(4)
2.844(2)
Bond Angles, deg
O(1)-Nd(1)*-O(2)
O(2)-Nd(1)-O(3)
O(4)-Nd(1)*-O(5)
67.9(2)
72.6(2)
71.6(2)
O(5)-Nd(2)-O(6)
O(7)-Nd(2)*-O(8)
O(8)-Nd(2)-O(9)
72.9(2)
68.9(2)
73.7(2)
a Symmetry operator (/): -x, y, -z þ 1/2.
69.5° and 73.1°) with the larger angle belonging to the “bite”
contained by the slightly elongated Nd-O(H) bonds. Due to
the steric bulk and coordinative saturation provided by the
ligand, only six shroud the core. This leaves a dicationic charge
which is balanced by two chloride anions in the outer coodina-
tion sphere of the cluster. These chloride ions are held to the
cluster by hydrogen bonding to two hydroxy groups with
Figure 2. Molecular structure of 1. Lattice solvent and H atoms
(excluding hydroxy) have been omitted for clarity.
Cationic lanthanoid clusters were synthesized by the reac-
tion of two equivalents of the respective ligand with one
equivalent of [LnCl2(H2O)6]Cl in the presence of methanolic
triethylamine. Subsequent removal of the methanol under
reduced pressure followed by dissolution in toluene resulted
in precipitation of triethylamine hydrochloride, enabling
isolation of solvated pure compounds after filtration. De-
pending on the ligand employed, tetrameric clusters of
composition [Ln4(Cl)2(O)(hpb)6]Cl2 (Ln = Nd (1), Ho (2),
Tb (3), and Er (4)) or dimeric complexes of [Ln2(hmb)5]Cl
(Ln = La (5), Nd (6), Tb (7), Dy (8), and Er (9)) were obtained.
Crystals of tetranuclear clusters (1-4) were difficult to
obtain; however, slow diffusion of diethyl ether into a solu-
tion containing 1 in wet dimethylformamide yielded single
crystals after four weeks (Figure 2). The solid state structure
was then determined by single crystal X-ray analysis.
˚
donor-acceptor distances of 3.007(7) and 3.018(7) A. The
remaining two hydroxy groups per cluster H-bond to DMF
˚
solvent molecules (donor-acceptor distance 2.645(10) A). A
number of solvent accessible voids exist between the clusters,
and these can tentatively be assigned to molecules of diethyl
ether. However, large amounts of disorder, thermal motion,
and the comparatively miniscule amount of electron density
mean that they cannot be satisfactorily modeled. One example
of this motif type has been reported previously containing
yttrium, albeit as a neutral species isolated in low yield.31
Exhaustive attempts at growing single crystals suitable for
X-ray crystallography for clusters 2-4 were unsuccessful;
hence, identification of these species was performed using
standard spectroscopic techniques. Recently, a literature pre-
cedent has emerged utilizing Raman spectroscopy to identify
the distinctive “fingerprints” inherent in a lanthanoid cluster
core.11 While the spectra themselves are complex and indivi-
dual resonances remain undetermined, the motif contains
unique Ln-Cl-Ln and Ln-O-Ln bands in an arrangement
active to Raman spectroscopy for analysis and comparison.
Unfortunately, the neodymium cluster was found to fluoresce
at a wavelength of 782 nm, coinciding with the emission
wavelength of the Renishaw diode laser. Similar luminescent
emissions have been observed from complexes incorporating
neodymium at approximately this wavelength.32 As a result,
analysis using a second laser source emitting at 514 nm was
undertaken, which elucidated weakened intensities for bands
in the region of 200 to 750 cm-1. The Raman spectra of 2-4
are compared with that of the known cluster 1 (Figure 3).
Consistent overlap of bands is observed between the four
species over the region of 800 to 2000 cm-1. At lower
wavenumbers, the peak intensities for 1 and 3 are too weak
for a definitive comparison, preventing confirmation of the
cluster motif by this technique alone.
The structure of 1 is shown in Figure 2, and a list of selected
bond lengths and angles is given in Table 1. The tetranuclear
cluster that resides on a 2-fold axis consists of a centralμ4-oxo
core with the Nd atoms bonded in a distorted tetrahedral
arrangement. Nd-O(oxide) distances are identical at
˚
˚
2.362(4) A and 2.366(4) A; the Nd-O-Nd angles average
107.4° and range from 100.1(3)° to 118.01(3)°. Within the
cluster core, two μ2-chloride anions bridge opposing pairs of
˚
˚
Nd atoms with Nd-Cl bonds of 2.850(2) A and 2.844(2) A
and Nd-Cl-Nd angles of 90.77(7)°. Nd atoms are also μ2-
bridged by the central O atom of each of the six ligands
surrounding the core. Each Nd is coordinated by three ligands.
Nd(1) is bound in a η2(O,O0) fashion to two ligands through the
diketyl moiety, and the third ligand binds η2(O0,OH) through
the central oxygen atom and the hydroxy oxygen atom. Nd(2) is
bound by two ligands in a η2(O0,OH) fashion and just one via
η2(O,O0) bonding. This gives each ligand an overall binding
mode of μ2-η2(O,O0)η2(O0,OH). Combined with the interac-
tions of the chloride and central oxide, these six Nd-O bonds
result in an overall coordination number of eight around the
metal centers. The outer diketyl oxygen atom has the shortest
˚
Nd-O bond lengths, averaging 2.37 A, whereas the central,
(31) Coles, M. P.; Hitchcock, P. B. Inorg. Chim. Acta 2004, 357, 4330.
bridging diketyl oxygen has Nd-O bond lengths averaging
ꢀ
(32) Gonc-alves, M. C.; Silva, N. J. O.; de Zea Bermudez, V.; Sa Ferreira,
˚
˚
2.50 A. The terminal OH average distance is 2.47 A. The two
“bite angles” provided by these ligands vary slightly (average
R. A.; Carlos, L. D.; Dahmouche, K.; Santilli, C. V.; Ostrovskii, D.; Correia
Vilela, I. C.; Craievich, A. F. J. Phys. Chem. B 2005, 109, 20093.

Article
Inorganic Chemistry, Vol. 49, No. 11, 2010 5019
Table 2. Assignment of Charged Species Observed for Clusters 1-4 by ESI(þ)-MS
cationic species
m/z (calculated)
m/z (found)
[Nd(hpb)(OH)(MeO)]Naþ MeOH
[Nd(hpb)(OH)(MeO)]Na 3MeOH
516.1
548.1
580.2
738.2
875.1
1115.2
1143.7
1157.7
1222.3
539.1
571.1
603.2
1200.8
1264.8
533.1
565.1
597.1
719.2
751.2
1157.3
1253.3
540.2
572.1
604.2
1203.3
516.2
548.2
580.2
738.1
876.3
1114.5
1142.6
1157.1
1223.2
539.2
571.3
603.2
1201.2
1265.1
532.9
564.9
597.0
720.8
752.8
1157.4
1252.8
540.2
572.2
604.2
1203.4
þ 3
þ 3
[Nd(hpb)(OH)(MeO)]Na 2MeOH
3
[Nd(hpb)2(MeO)]Naþ
[Nd2(O)(hpb)2(MeO)]þ
[Nd2(O)(hpb)3]þ
[Nd4(Cl)2(O)(hpb)6]2þ
[Nd4(OH)2(O)(hpb)6]2þ 2MeOH
[Nd4(OH)2(O)(hpb)6] 6MeOH
2þ 3
3
[Ho(hpb)(OH)(MeO)]Naþ MeOH
[Ho(hpb)(OH)(MeO)]Na 2MeOH
þ 3
þ 3
[Ho(hpb)(OH)(MeO)]Na 3MeOH
3
[Ho4(OH)2(O)(hpb)6]2þ 2MeOH
[Ho4(OH)2(O)(hpb)6] 6MeOH
2þ 3
3 þ
[Tb(hpb)(OH)(MeO)]Na MeOH
þ 3
[Tb(hpb)(OH)(MeO)]Na 2MeOH
þ 3
Figure 3. Raman spectra of Nd (1), Ho (2), Tb (3), and Er (4).
[Tb(hpb)(OH)(MeO)]Na 3MeOH
3
[Tb(hpb)2(H2O)]þ
[Tb(hpb)2(H2O)]Naþ MeOH
3
A comparison of the infrared spectra obtained for com-
plexes 1-4 illustrates identical features from 4000 to 500
cm-1. Twin resonances at 1592 and 1565 cm-1, correspond-
ing to the υ(CdC) and υ(CdO) vibrations, are prominent
and shifted to lower wavenumbers compared with the free
ligand at 1639 and 1607 cm-1. Broadened bands at 1447 and
1370 cm-1 correspond to aromatic υ(CdC) stretch absorp-
tions, and a medium intensity band at 1264 cm-1 was attri-
buted to a ketone-bending mode.33,34
[Tb4(OH)2(O)(hpb)6]2þ
[Tb4(OH)2(O)(hpb)6]2þ 6MeOH
[Er(hpb)(OH)(MeO)]Na MeOH
3 þ
þ 3
[Er(hpb)(OH)(MeO)]Na 2MeOH
þ 3
[Er(hpb)(OH)(MeO)]Na 3MeOH
3
[Er2(O)(OH)(hpb)3]Naþ
Scheme 2. Fragmentation Pathway Observed for Clusters 1-4
Elemental analyses performed on a vacuum-dried crystal-
line sample of 1 and bulk samples for compounds 2-4 gave
results consistent with solvates. As recrystallization proved
impossible for compounds 2-4, a low hydrogen percentage is
indicative of small amounts of lanthanoid chloride contain-
ing intermediates present in these samples. Thermogravi-
metric analysis was used to compare the thermal degradation
pathway for compounds 1-4. Weight loss percentages of
between 4.22% and 8.63% were observed over a temperature
range of 50 to 200 °C. We postulate that these losses represent
liberation of solvent molecules from the crystal lattice,
combined with four equivalents of HCl displaced by second-
ary deprotonation of the ligands. A comparison of the weight
loss profiles for complexes 1-4 from 200 to 650 °C shows a
near identical thermal degradation pathway. In all four cases,
the onset of the first incremental loss corresponding to 15%
by weight occurs within the range of 272.4-282.3 °C.
Secondary losses of 15% (onset temp: 275 °C) and 10%
(onset temp: 517 °C) were seen to occur in a similar con-
current manner. These losses are attributed to degradation of
the ligand to give simple volatile components. It is likely that
lanthanoid oxide species and charred remnants of the ligand
make up the remaining 50% by weight present after heating
has concluded.
The chloride bridged dicationic species [Ln4(Cl)2(O)(hpb)6]2þ
was observed only in the case of 1. Rapid hydrolysis to an
hydroxo bridged tetranuclear dication [Ln4(OH)2(O)(hpb)6]2þ
was instead observed for 1-3. Fragmentation of this species
was found to produce one of two possible cationic species, a
mononuclear cation, [Ln(hpb)(OH)(MeO)]Naþ, seen as domi-
nant peaks corresponding to methanol solvates, and the
dimeric species [Ln2(O)(hpb)3]þ observed for both 1 and 4.
Displacement of a single ligand by methanol or water gave the
final dimeric cation observed [Nd2(O)(hpb)2(OR)]þ (R = H,
Me). While there was no direct evidence of tetranuclear species
for erbium cluster 4 by ESI-MS, comparison of the Raman
spectrum with that of holmium cluster 2 (Figure 3) gives
considerable evidence to support the presence of an identical
core motif.
Varying the ligand to contain a p-methoxy phenyl group
(Hhmb) resulted in marked changes to the composition of the
cluster. Single crystals of compounds 5 and 7 were obtained
by slow evaporation of toluene solutions of these com-
pounds. X-ray crystallography determinations on com-
pounds 5 and 7 showed that they exhibit the same cationic
dimeric motif (Figure 4) with a varying number of solvent
molecules located in the crystal lattice. Terbium cluster 7 is
representative of series 5-9 as determined by mass spectro-
metry, infrared spectroscopy, and elemental analyses and is
discussed in further detail below. Only the X-ray crystal
structure of compound 7 will be discussed here, while
the data for compound 5 are available as Supporting
Information.
An analysis of 1-4 by electrospray mass spectrometry
(ESI-MS) gave cationic fragments formed by dissociation of
the cluster (Table 2). Dominant species are listed with the
proposed molecular formula. In each case, only the most
prominent isotope is reported.
Analyses of these fragments allow us to postulate the
fragmentation pathway (Scheme 2) for each cluster species.
(33) Nakamoto, K. Infrared and Raman Spectra of Inorganic and Co-
ordination Compounds, 4th ed.; Wiley-Interscience Publication: New York,
1986; p 259.
(34) Junge, H.; Musso, H. Spectrochim. Acta, Part A 1968, A24, 1219.

5020 Inorganic Chemistry, Vol. 49, No. 11, 2010
Andrews et al.
Figure 4. Molecular structure of 7. Lattice solvent and hydrogen atoms (excluding hydroxy) have been omitted for clarity. The structure of compound 5 is
similar.
˚
˚
Table 3. Selected Bond Lengths and Angles for 7
donor-acceptor distances of 3.021(6) A and 3.058(7) A. The
remaining two ligands can be considered as capping, as they
bond to only one metal each with an overall bonding mode of
η2(O,O0). These are more symmetrical interactions with outer
˚
Bond Lengths, A
Tb(1)-O(1)
Tb(1)-O(2)
Tb(1)-O(5)
Tb(1)-O(6)
Tb(1)-O(10)
Tb(1)-O(11)
Tb(1)-O(13)
Tb(1)-O(14)
2.311(5)
2.456(5)
2.337(5)
2.397(5)
2.424(5)
2.417(5)
2.291(6)
2.313(5)
Tb(2)-O(2)
Tb(2)-O(3)
Tb(2)-O(6)
Tb(2)-O(7)
Tb(2)-O(9)
Tb(2)-O(10)
Tb(2)-O(17)
Tb(2)-O(18)
2.412(5)
2.430(6)
2.415(5)
2.413(6)
2.286(6)
2.398(5)
2.272(6)
2.332(6)
˚
˚
Tb-O bonds of 2.291(6) A and 2.272(6) A and central Tb-O
˚
˚
bonds of 2.313(5) A and 2.332(16) A. The respective bite
angles are 73.3(2)° and 74.4(2)°. A single hydroxy group
from a capping ligand hydrogen-bonds to a chloride asso-
ciated with a neighboring cluster (donor-acceptor distance
˚
3.213(7) A), forming a pseudo polymer in the solid state
(Figure 5).
Bond Angles, deg
In compounds 5-9, the 5-hydroxy-1,3-diketonate hmb
anion binds by two different coordination modes: (a) as a
double chelator μ2-η2(O,O0)η2(O0,OH) or (b) as a bidentate
nonbridging ligand η2(O,O0) (Figure 6). In compounds 1-4,
however, only coordination mode (a) is observed.
O(1)-Tb(1)-O(2)
O(2)-Tb(2)-O(3)
O(5)-Tb(1)-O(6)
O(9)-Tb(2)-O(10)
O(10)-Tb(1)-O(11)
71.84(18)
O(17)-Tb(2)-O(18)
Tb(1)-O(2)-Tb(2)
Tb(1)-O(6)-Tb(2)
Tb(1)-O(10)-Tb(2)
74.4(2)
99.1(2)
100.7(2)
100.4(2)
73.86(18)
70.43(19)
73.29(19)
72.85(18)
The infrared spectra for complexes 5-9 show intense
bands at 1585 and 1553 cm-1, indicative of the υ(CdO)
and υ(CdC) vibrations. These bands are shifted to lower
wavenumbers relative to the ligand where they appear as an
unresolved broad band at 1598 cm-1. Most of the observed
bands mirror those seen for clusters 1-4, with the exception
of a well-defined para-substituted out of plane stretch ob-
The structure of 7 can be seen in Figure 4, and a selection of
bond lengths and angles are given in Table 3. Unlike the
cluster structure obtained using the Hhpb ligand, the addition
of the MeO group in the para position in Hhmb has resulted
in the formation of a dinuclear complex of composition
[{Tb2(hmb)5}Cl (toluene)2]. The two metal centers are μ2-
served at 840 cm-1 33,34
.
3
bridged by the central O atoms of three ligands with average
The thermogravimetric plots obtained for dimeric species
5-9 dried in vacuo display dramatic losses in weight percen-
tage between 100 and 300 °C. A thermal loss of lattice bound
toluene molecules (onset temp: 50-110 °C) was found to
overlap with the first decomposition loss of 18% (onset temp:
116 °C), hindering accurate determination of lattice bound
solvents. A second weight loss of between 14 and 24%
occurred at approximately 280 °C. Displacement of a biden-
tate ligand gives a weight loss of 16%, consistent with the first
weight loss. It is postulated that the second process is thermal
cleavage of the remaining ligands to yield volatile anisole.
Elemental analyses performed on the dried crystalline pro-
ducts gave results consistent with the solid-state dimer
˚
Tb-O distances of 2.43 A and near identical Tb-O-Tb
angles of 99.1(2)°, 100.7(2)°, and 100.4(2)° for O(2, 6, and 10).
These three ligands have overall binding modes of
μ2-η2(O,O0)η2(O0,OH), as was seen in 1. The outer O atoms
˚
of the diketyl groups are the shorter, averaging 2.31 A, with
˚
the Tb-O(hydroxy) bonds averaging 2.42 A. The average
diketyl ‘bite’ angles are 71.9°, which is not significantly
different from the hydroxy contained bite angles, which
average 72.5°. Tb(1) is bonded to two ligands in an η2(O,O0)
fashion and one via η2(O0,OH) bonding. The reverse, how-
ever, is true for Tb(2), and the two hydroxy groups which are
bound to the Tb(2) hydrogen-bond to the Cl anion with

Article
Inorganic Chemistry, Vol. 49, No. 11, 2010 5021
Figure 5. Extended structure of 7 showing hydrogen bonding interactions.
(intermediate A; Figure 7). With the assumption that the
coordination number of the lanthanoid centers remains
constant throughout the synthesis, coordination of the three
ligands to two [LnCl2(H2O)6]Cl units under basic conditions
results in displacement of three chloride ions and 11 coordi-
nated water molecules. The exchange of coordinated water
molecules forthe ligands (intermediateA) likely occurs dueto
favorable changes in entropy, as predicted by the chelate
effect.35 Two base mediated pathways continue from inter-
mediate A: either fusion with a second equivalent of inter-
mediate A mediated by deprotonation of the single
coordinated water, yielding the cationic cluster motif B after
liberation of one equivalent of water, or displacement of the
remaining coordinated chlorides and water molecule by
two equivalents of the ligand, resulting in the cationic dimer
motif C. The choice of pathway likely depends on numerous
factors such as identity of the ligand and differing solubilities
of both intermediates and products. In either case, cationic
products are generated due to the inability of the base to
penetrate the sterically bulky cyclopentane rings capping
each coordinated hydroxy group. As a result, the periphery
of the cluster is stabilized by sterically demanding, mono-
anionic ligands which crowd the coordination sphere of the
core, while minimizing counteraction of charge.
In addition to demonstrating control over the cationic
nature of the products, the first example of synthesis of tetr-
americ motif B using an air- and moisture-stable methodo-
logy is detailed. Prior reports of analogous chloride bridged
tetrameric species are typically air-sensitive39-46 or partially
hydrolyzed products of air-sensitive reaction mixtures.47,48
We have established that hydrated lanthanoid chloride salts
can be employed to synthesize such clusters, provided the
number of intermediate coordinated water molecules can be
limited and monoanionic charge on the ligands maintained.
Figure 6. Coordination modes (a) μ2-η2(O,O0)η2(O0,OH) and (b) η2(O,O0)
observed in lanthanoid species reported.
structures. The number of toluene molecules evident was in
all cases lower than that predicted by TGA, suggesting that
the lattice solvent is slowly lost in vacuo.
The clusters 5-9 were observed by ESI-MS as both cations
and dications. Cationic species corresponding with fragmen-
tation of the cluster were in most instances also observed. A
less complex fragmentation pathway was observed than for
clusters 1-4, whereby the multiply ionized cluster cleaves to
yield a combination of fragments including [Ln(hmb)2]þ,
[Ln(hmb)3]Hþ, and [Ln(hmb)4]2Hþ. A complete list of ob-
served fragments is provided in the Supporting Information,
as are the crystal data for 5.
The χMT value of 25.9 cm3 K mol-1 determined at 300 K
for dimer 7 is typical of two uncoupled TbIII ions, free of
magnetic exchange interactions. Across the range of 300 to
100 K, the nature of χT was found to be largely temperature
independent, which suggests a total population of all spin
states and that magnetic interactions between the two TbIII
ions are very weak. Below 50 K, however, the χT value
decreases rapidly down to 18.1 cm3 K mol-1 at 5 K, which
may be attributed to the depopulation of the Stark sublevels
of the TbIII ions. From this investigation, it has been
concluded that the coupling between the TbIII ions is very
weak, and the observed decrease in χT at lower temperatures
is predominantly due to thermal depopulation of the Stark
sublevels originating from the TbIII single ion, generated
when the free ion states are split by field and spin-orbit
coupling effects. Similar effects and conclusions have been
observed in both tetranuclear and mononuclear TbIII com-
pounds reported in the literature.36-38 An expanded discus-
sion and plot of molar magnetic susceptibility and χMT vs T
for 7 can be found as Supporting Information.
(39) Evans, W. J.; Sollberger, M. S.; Hanusa, T. P. J. Am. Chem. Soc.
1988, 110, 1841.
(40) Zhou, X.; Ma, H.; Wu, Z.; You, X.; Xu, Z.; Huang, X. J. Organomet.
Chem. 1995, 503, 11.
(41) Wang, J.; Li, S.; Zheng, C.; Li, A.; Hosmane, N. S.; Maguire, J. A.;
Roesky, H. W.; Cummins, C. C.; Kaim, W. Organometallics 2004, 23, 4621.
(42) Wang, J.; Li, S.; Zheng, C.; Hosmane, N. S.; Maguire, J. A.; Roesky,
H. W.; Cummins, C. C.; Kaim, W. Organometallics 2003, 22, 4390.
(43) Zhong-Sheng, J.; Jing-Wen, G.; Ge-Cheng, W.; Jing-Yu, H.; Qi, S.
Chin. J. Struct. Chem. 1990, 9, 140.
The postulated mechanism for the observed tetranuclear
clusters 1-4 and dimeric species 5-9 entails formation of
a dimeric species stabilized by three tridentated ligands
(44) Ji-Zhu, J.; Ge-Cheng, W.; Zhong-Sheng, J.; Wen-Qi, C. Chin. J.
Struct. Chem. 1992, 11, 369.
(35) Schwarzenbach, G. Helv. Chim. Acta 1952, 35, 2344.
(36) Chen, X.-M.; Wu, Y.-L.; Tong, Y.-X.; Sun, Z.; Hendrickson, D. N..
Polyhedron 1997, 16, 4265.
(45) Jing-Wen, G.; Qi, S.; Jing-Yu, H.; Yong-Hua, L. Chin. J. Struct.
Chem. 1990, 9, 184.
(46) Xiang-Gao, L.; Jing-Zhi, L.; Shong-Chen, J.; Yong-Hua, L.;
Guo-Zhi, L. Chin. J. Struct. Chem. 1991, 10, 60.
(47) Pi, C.; Wan, L.; Gu, Y.; Zheng, W.; Weng, L.; Chen, Z.; Wu, L. Inorg.
Chem. 2008, 47, 9739.
(48) Coles, M. P.; Hitchcock, P. B. Inorg. Chim. Acta 2004, 357, 4330.
€
(37) Bircher, R.; Abrahams, B. F.; Gudel, H. U.; Boskovic, C. Polyhedron
2007, 26, 3028.
(38) Caneschi, A.; Dei, A.; Gatteschi, D.; Poussereau, S.; Sorace, L.
Dalton Trans. 2004, 1048.

5022 Inorganic Chemistry, Vol. 49, No. 11, 2010
Andrews et al.
Figure 7. Postulated mechanism for the formation of tetrameric (B) and dimeric (C) motifs from a common precursor A. The omission of cyclopentane
rings and replacement of the farthest ligand of intermediate A with a bold annotated line has been undertaken for clarity. Each step is base-mediated.
Conclusions
for Hhpb or 0.68 g, 4.0 mmol of p-anisoyl chloride for Hhmb)
was next added with rapid stirring. After one minute, two
further equivalents of LiHMDS (5.0 mL, 8 mmol) were added
in one portion followed by stirring for an additional minute.
A second equivalent of cyclopentanone (0.33 g, 4.0 mmol) was
added and the solution allowed to warm to room temperature.
The reaction was quenched with water (∼10 mL) and acidified
to pH 5 with 1 M HCl. The solution was extracted with ethyl
acetate (3ꢀ 50 mL) and the organic extracts dried (MgSO4) and
concentrated to dryness under reduced pressure. The crude
product was then purified by column chromatography yielding
the 5-hydroxy-1,3-diketone.
We have shown that 5-hydroxy-1,3-diketonate ligands
stabilize cationic lanthanoid clusters. When treated with rare
earth salts, (R/S,Z)-10-hydroxy-3 (hydroxy(phenyl)methylene)-
bi(cyclopentan)-2-one (Hhpb) and the closely related
p-methoxyphenyl derivative (Hhmb) yielded tetranuclear
and dinuclear clusters, respectively. These are identified as
[Ln4(Cl2)(O)(hpb)6]Cl2 (Ln = Nd (1), Ho (2), Tb (3), and Er
(4)) and [Ln2(hmb)5]Cl (Ln = La (5), Nd (6), Tb (7), Dy (8),
and Er (9)). The cluster motif was found to change dependent
on the size and shape of the ligand; for example, the tetra-
nuclear compound adopts a tetrahedral motif stabilized by
coordination of the 5-hydroxyl group. Taken collectively, the
clusters provide the first successful attempt at synthesizing
and stabilizing cationic lanthanoid clusters through using
specifically tailored diketonate ligands.
(R/S,Z)-10-Hydroxy-3-(hydroxy(phenyl)methylene)bi(cyclopentan)-
2-one (Hhpb). Orange crystals (0.61 g, 56% yield). Mp:
1
86.3-87.3 °C. H NMR (CDCl3): δ (ppm) 1.69 (m, 2H, H11),
1.92 (dp, 4H, J = 8.0 Hz, H15 H16), 2.26 (m, 2H, H10 H12B), 2.47
(t, 2H, J = 8.0 Hz, H17), 2.51 (m, 1H, H12A), 2.78 (s, 1H, OH),
2.85 (t, J = 7.5 Hz, H14), 7.43 (m, 3H, m-PhH p-PhH), 7.75 (d,
2H, J = 6.0 Hz, o-PhH), 14.49 (s, 1H, OH). 13C NMR (CDCl3):
δ (ppm) 23.85 (C16); 24.01 (C15); 24.84 (C12); 26.34 (C11); 36.20
(C14); 56.02 (C17); 82.94 (C10); 110.02 (C8); 128.20 (C3 C7);
128.38 (C4 C6); 131.22 (C2); 134.23 (C5); 169.14 (C1); 211.59
(C9). IR (KBr): 3566s, 3447m, 2961m, 2873m, 1639s, 1607s,
1588s, 1568s, 1491m, 1472w, 1448m, 1365s, 1331m, 1279m, 1184m,
1163m, 1141m, 1083m, 1029w, 1001w, 975w, 932w, 872m, 801m,
782m, 698s, 669w, 640w, 596w, 529w, 450w cm-1. HRMS (ESI)
calcd for [M - H]-: 271.1334. Found: 271.1341.
Experimental Section
Materials and Equipment. Chemicals were purchased from
Sigma-Aldrich and were used as received. Solvents used were
reagent grade and purified by usual methods. 1H and 13C NMR
spectra were recorded on a Bruker AM 300 spectrometer and
Varian Unity Nova 500 spectrometer. Chemical shifts were
recorded on the δ scale and referenced against the solvent.
Protons and carbons are labeled according to the crystallo-
graphic labeling in Figure 1. Solid-state IR spectra were re-
corded on a Bruker Equinox 55 Infrared Spectrometer fitted
with a Specac Diamond ATR source. Raman spectroscopy was
performed with either a Renishaw RM2000 spectrometer fitted
with a 782 nm Renishaw diode laser or a Renishaw Invia
spectrometer fitted with a 514 nm argon ion laser. TGA analyses
was performed using a Setaram TG92 instrument with a heating
rate of 10 K/min under nitrogen in a range from 50 to 650 °C.
Melting points were measured on an SMP3 Stuart Scientific
Melting Point Apparatus in an open capillary and were uncali-
brated. Elemental analyses were performed by Campbell Micro-
analytical Laboratory, Department of Chemistry, University of
Otago, Dunedin, New Zealand. Powder diffraction analyses
were attempted on the crude microcrystalline samples (Ho, Tb,
and Er), and the more prominent features predicted by LAZY
Pulverix from the single crystal of the Nd species were observed,
albeit with broadening of the diffractogram peaks. The samples
subjected to powder diffraction were bulk crude samples and
were not recrystallized in the same manner as the samples used
for single crystal X-ray diffraction, and therefore some amor-
phous material is probably present, broadening the peaks.
Synthesis of Hhpb and Hhmb. To an anhydrous THF (5 mL)
solution of cyclopentanone (0.33 g, 4.0 mmol) cooled to -78 °C
was added LiHMDS (2.5 mL, 1.6 M in hexanes, 4.0 mmol). One
equivalent of acid chloride (0.56 g, 4.0 mmol of benzoyl chloride
(R/S,Z)-10-Hydroxy-3-(hydroxy(4-methoxyphenyl)methylene)-
bi(cyclopentan)-2-one (Hhmb). Yellow crystals (0.88 g, 73%
1
yield). Mp: 61.8-62.8 °C. H NMR (CDCl3): δ 1.60 (m, 4H,
H15 H16); 1.85 (m, 4H, H14 H15); 2.28 (m, 2H, H12); 2.81 (m, 2H,
H11); 2.91 (dd, J1 = 2.0, J2 = 11.0 Hz, H10); 3.51 (s, 1H, OH);
3.86 (s, 3H, CH3); 6.96 (d, 2H, J = 9.0 Hz, PhH); 7.77 (d, 2H,
J = 9.0 Hz, PhH); 14.64 (s, 1H, OH). 13C NMR (CDCl3): δ
24.14 (C16); 24.27 (C15); 25.00 (C12); 26.81 (C11); 36.30 (C14);
38.90 (C17); 55.65 (CH3); 55.89 (C10); 83.27 (C13); 109.06 (C8);
114.05 (C4 C6); 126.78 (C2); 130.46 (C3 C7); 162.32 (C5); 169.84
(C1); 210.89 (C9). IR (KBr): 3449m, 2954s, 2870m, 1733m,
1661m, 1598s, 1508s, 1455m, 1420w, 1374s, 1255s, 1172s, 1116s,
1061w, 1027m, 840m cm-1. HRMS (ESI) calcd for [M - H2O]þ:
285.1491. Found: 285.1484. HRMS (ESI) calcd for [M þ H]þ:
303.1596. Found: 303.1594. HRMS (ESI) calcd for [M þ Na]þ:
325.1416. Found: 325.1412.
General Procedure for Cluster Synthesis. To a round-bot-
tomed flask equipped with a stirrer bead were added the relevant
ligand and lanthanoid trichloride in a 2:1 molar ratio. The
starting materials were dissolved in methanol, followed by a
slow, dropwise addition of 4 equivalents of triethylamine.
Reaction times unless otherwise stated were 24 h. After this
time, the solvent was removed and the residue stirred in toluene
(∼2 mL) for 1 h. The solution was then filtered and left in an
open vial to slowly evaporate.

Article
Inorganic Chemistry, Vol. 49, No. 11, 2010 5023
[Nd4(Cl2)(O)(hpb)6]Cl2 (1). Pale yellow crystals. Yield: 24%.
Mp: 210-215 °C (dec). Anal. calcd for C102H114Cl4Nd4O19
1305m, 1247s, 1167s, 1110w, 1023s, 975 m, 840m cm-1. MS (ESI)
calcd for [Nd(hmb)2]þ: 744.2. Found: 744.5. MS (ESI) calcd for
3
2H2O: C, 51.1; H, 5.0. Found: C, 51.1; H, 5.0. IR (ATR): 3057
m, 2946 m, 1592s, 1565s, 1494s, 1370s, 1313w, 1264s, 1073 m,
1026 m, 922w, 876w, 827m, 791m, 710s, 692s cm-1. Raman:
1600, 1563, 1495, 1497, 1291, 1316, (br)1280, 1223, 1184, 1001,
879, 794, 568, 455, 128. MS (ESI) calcd for [Nd(hpb)(OH)-
[Nd2(hmb)5Cl]2Na2þ H2O: 945.2. Found: 945.4. MS (ESI) calcd
3
for [Nd2(hmb)5Cl]2Na2þ (H2O, EtOH): 968.3. Found: 969.4. MS
3
(ESI) calcd for [Nd(hmb)3]Hþ: 1046.3. Found: 1046.7.
[Tb2(hmb)5]Cl (7). Yellow crystals. Yield 34%. Mp: 150-160 °C
(dec). Anal. calcd for C90H110ClTb2O20 2Tol: C, 61.0; H, 6.2.
3
(MeO)]Naþ MeOH: 516.1. Found: 516.2. MS (ESI) calcd for
Found: C, 61.1; H, 6.2. IR (ATR): νmax 2945m, 1587s, 1556s,
1513w, 1435s, 1381s, 1304m, 1247s, 1167s, 1107w, 1026s, 975m,
840m cm-1. MS (ESI) calcd for [Tb(hmb)2]þ: 761.2. Found:
761.6. MS (ESI) calcd for [Tb(hmb)3]Hþ: 1063.4. Found: 1063.6.
MS (ESI) calcd for [Tb(hmb)4]2Hþ: 1365.5. Found: 1365.9. MS
(ESI) calcd for [Tb2(hmb)5]þ: 1823.6. Found: 1823.3.
3
[Nd(hpb)(OH)(MeO)]Naþ 3MeOH: 548.1. Found: 548.2. MS
3
(ESI) calcd for [Nd(hpb)(OH)(MeO)]Naþ 2MeOH: 580.2.
3
Found: 580.2. MS (ESI) calcd for [Nd(hpb)2(MeO)]Naþ: 738.2.
Found: 738.1. MS (ESI) calcd for [Nd2(O)(hpb)2(MeO)]þ: 875.1.
Found: 876.3. MS (ESI) calcd for [Nd2(O)(hpb)3]þ: 1115.5.
Found: 1114.5. MS (ESI) calcd for [Nd4(Cl)2(O)(hpb)6]2þ
:
1143.7. Found: 1142.6. MS (ESI) calcd for [Nd4(OH)2(O)-
[Dy2(hmb)5]Cl (8). Yellow crystals. Yield: 17%. Mp: 215-
225 °C (dec). Anal. calcd for C90H110ClDy2O20: C, 62.5; H, 5.9.
Found: C, 62.7; H, 6.0. IR (ATR): νmax 2945m, 1588s, 1559s,
1513w, 1433s, 1371s, 1306m, 1246s, 1166s, 1107w, 1026s, 987m,
838m, 764m, 716m, 666m, 621m cm-1. MS (ESI) calcd for
(hpb)6]2þ 2MeOH: 1157.7. Found: 1157.1. MS (ESI) calcd for
3
[Nd4(OH)2(O)(hpb)6]2þ 6MeOH: 1222.3. Found: 1223.2.
[Ho4(Cl2)(O)(hpb)6]Cl2 (2). Orange powder. Yield: 65%. Mp:
3
[Dy2(hmb)5Cl]2Na2þ 3H2O: 983.3. Found: 983.5. MS (ESI)
215-220 °C (dec). Anal. calcd for C102H114Cl4Ho4O19 Tol: C,
3
3
calcd for [Dy2(hmb)5Cl]2Na2þ (3H2O, EtOH): 1006.3. Found:
51.4; H, 4.8. Found: C, 51.1; H, 4.3. IR (ATR): νmax 2947m,
1596s, 1569s, 1495s, 1382s, 1314w, 1281s, 1074m, 1027m, 921w,
877w, 828m, 791m, 711s, 693s cm-1. Raman: 1602, 1563, 1496,
1480, 1445, 1317, 1293, 1271, 1222, 1179, 1158, 1028, 1001, 880,
847, 794, 728, 719, 664, 618, 569, 516, 454, 404, 301, 270, 218,
3
1006.1. MS (ESI) calcd for [Dy2(hmb)5Cl]2Na2þ (4H2O,
EtOH): 1015.3. Found: 1016.4.
3
[Er2(hmb)5]Cl (9). Brown crystals. Yield 28%. Mp: 220-225 °C
(dec). Anal. calcd for C102H114Cl4Er4O19: C, 57.4; H, 5.9.
Found: C, 57.8; H,5.7. IR (ATR): νmax 2948m, 1589s, 1562s,
1513w, 1434s, 1378s, 1290m, 1246s, 1167s, 1108w, 1027s, 911w,
838m, 761m, 717m, 664w, 622m cm-1. MS (ESI) calcd for
[Er2(hmb)5]Na2þ: 931.3. Found: 930.1. MS (ESI) calcd for
130. MS (ESI) calcd for [Ho(hpb)(OH)(MeO)]Naþ MeOH:
3
539.1. Found: 539.2. MS (ESI) calcd for [Ho(hpb)(OH)-
(MeO)]Naþ 2MeOH: 571.1. Found: 571.3. MS (ESI) calcd
3
for [Ho(hpb)(OH)(MeO)]Naþ 3MeOH: 603.2. Found: 603.2.
3
[Er2(hmb)5Cl]2Na2þ (H2O, EtOH): 992.3. Found: 992.2. MS
MS (ESI) calcd for [Ho4(OH)2(O)(hpb)6]2þ 2MeOH: 1200.8.
3
3
(ESI) calcd for [Er2(hmb)5Cl]2Na2þ (H2O, 2EtOH): 1015.8.
Found: 1201.2. MS (ESI) calcd for [Ho4(OH)2(O)(hpb)6]2þ
6MeOH: 1264.8. Found: 1265.1.
[Tb4(Cl2)(O)(hpb)6]Cl2 (3). Yellow powder. Yield: 58%. Mp:
3
3
Found: 1016.1. MS (ESI) calcd for [Er2(hmb)5Cl]2Na2þ
(2H2O, 2EtOH): 1024.8. Found: 1025.1. MS (ESI) calcd for
[Er(hmb)3]Hþ: 1072.4. Found: 1072.1. MS (ESI) calcd for
[Er(hmb)4]2Hþ: 1374.5. Found: 1374.3.
3
215-225 °C (dec). Anal. calcd for C102H114Cl4Tb4O19 H2O: C,
3
49.7; H, 4.7. Found: C, 49.7; H, 4.3. IR (ATR): νmax 2947m,
1594s, 1569s, 1495s, 1378s, 1314w, 1281s, 1074m, 1026m, 922w,
877w, 828m, 791m, 711s, 693s cm-1. Raman: 1601, 1497, 1445,
1316, 1273, 1273, 1162, 1146, 1027, 1002, 877, 834, 790, 618, 404,
X-Ray Crystallography. Crystalline samples of Hhpb, 1, and 7
were mounted on glass fibers in viscous hydrocarbon oil. Crystal
data were collected using either an Enraf-Nonius Kappa CCD
or a Bruker X8 APEX CCD instrument with monochromated
270, 217. MS (ESI) calcd for [Tb(hpb)(OH)(MeO)]Naþ MeOH:
3
˚
Mo KR radiation, λ = 0.71073 A. All data were collected at
533.1. Found: 532.9. MS (ESI) calcd for [Tb(hpb)(OH)-
(MeO)]Naþ 2MeOH: 565.1. Found: 564.9. MS (ESI) calcd for
123 K, maintained using an open flow of nitrogen from an
Oxford Cryostreams cryostat. Structural solution and refine-
ment was carried out using SHELXL-9749 utilizing the graphi-
cal interface X-Seed.50 Data were corrected for absorption using
the SADABS51 or SORTAV52 packages. Data collection and
refinement parameters are given in Table 4. Disordered solvent
within the lattice of 1 was initially modeled as Et2O and
sustained refinement well; however it did not account for all
residual electron density and encroached to closely to the main
residue. No other solvent molecules sustained refinement, and
therefore the residual electron density was removed using
PLATON Squeeze. The electron/cell count was given as 258
3
[Tb(hpb)(OH)(MeO)]Naþ 3MeOH: 597.1. Found: 597.0. MS
3
(ESI) calcd for [Tb(hpb)2(H2O)]þ: 719.2. Found: 720.8. MS
(ESI) calcd for [Tb(hpb)2(H2O)]Naþ MeOH: 751.2. Found:
3
752.8. MS (ESI) calcd for [Tb4(OH)2(O)(hpb)6]2þ: 1157.3.
Found: 1157.4. MS (ESI) calcd for [Tb4(OH)2(O)(hpb)6]2þ
6MeOH: 1253.3. Found: 1252.8.
3
[Er4(Cl2)(O)(hpb)6]Cl2 (4). Orange powder. Yield: 60%. Mp:
220-225 °C (dec). Anal. calcd for C102H114Cl4Er4O19: C, 50.3;
H, 4.7. Found: C, 50.3; H, 4.2. IR (ATR): νmax 2947m, 1594s,
1569s, 1495s, 1377s, 1315w, 1280s, 1074m, 1027m, 922w, 877w,
828m, 791m, 710s, 692s cm-1. Raman: 1600, 1563, 1497, 1480,
1444, 1318, 1293, 1273, 1222, 1177, 1157, 1030, 1002, 876, 843,
795, 725, 720, 666, 618, 570, 512, 454, 405, 302, 267, 218, 131. MS
3
˚
and the solvent accessible void as 2270 A . During refinement of
the structure of 7, considerable disorder in all of the toluene
solvent molecules meant that disordered components did not
sustain anisotropic refinement, and even when refined isotropi-
cally the phenyl rings had to be restrained as ideal hexagons.
Disorder in the methoxy groups of ligands 1 and 5 was also
refined isotropically. Their thermal parameters were refined
collectively, and the coordinates of C92 and C92A were fixed
together. The phenyl rings C12 to C17 were constrained using
the ISOR command as they appeared to have a very small
component of disorder; however this could not sustain refinement.
Large amounts of thermal movement in the flexible 5-membered
(ESI) calcd for [Er(hpb)(OH)(MeO)]Naþ MeOH: 540.2.
3
Found: 540.2. MS (ESI) calcd for [Er(hpb)(OH)(MeO)]Naþ
2MeOH: 572.1. Found: 572.2. MS (ESI) calcd for [Er(hpb)(OH)-
3
(MeO)]Naþ 3MeOH: 604.2. Found: 604.2. MS (ESI) calcd for
3
[Er2(O)(OH)(hpb)3]Naþ: 1203.3. Found: 1203.4.
[La2(hmb)5]Cl (5). Yellow crystals. Yield 26%. Mp: 210-218
°C (dec). Anal. calcd for C90H110ClLa2O20 Tol: C, 60.8; H, 6.2.
3
Found: C, 60.1; H, 6.4. IR (ATR): νmax 2944m, 1588s, 1554s,
1512w, 1434s, 1371s, 1307m, 1248s, 1168s, 1109w, 1029s, 841m
cm-1. MS (ESI) calcd for [La(hmb)2]þ: 741.2. Found: 741.6. MS
(ESI) calcd for [La(hmb)3]Hþ: 1043.3. Found: 1043.7. MS (ESI)
calcd for [La(hmb)4]2Hþ: 1345.5. Found: 1347.0. MS (ESI)
calcd for [La2(hmb)5]þ: 1783.5. Found: 1783.1.
(49) Sheldrick, G. M. Acta Crystallogr., Sect. A 2008, A64, 112.
(50) Barbour, L. J. XSEED: A graphical interface for use with the
SHELX97 program suite; University of Missouri: Columbia, MO, 1999.
[Nd2(hmb)5]Cl (6). Orange crystals. Yield 36%. Mp: 150-160 °C
(dec). Anal. calcd for C90H110ClNd2O20: C, 58.9; H, 6.0. Found: C,
60.0; H, 6.2. IR (ATR): νmax 2951m, 1585s, 1553s, 1433s, 1388s,
€
(51) Sheldrick, G. M. SADABS, version 2.03; University of Gottingen:
€
Gottingen, Germany, 1997.
(52) Blessing, R. H. J. Appl. Crystallogr. 1997, 30, 421.

5024 Inorganic Chemistry, Vol. 49, No. 11, 2010
Andrews et al.
Table 4. Crystallographic Data for Hhpb, 1, 5, 7
complex
Hhpb
1
5
7
empirical formula
fw
cryst syst
C17H20O3
272.33
monoclinic
P21/n
6.7644(4)
10.5736(6)
19.6341(15)
90
93.811(2)
90
1401.22(16)
4
1.291
0.087
584
2.08 to 25.00
0.0970
C108H128Nd4N2O21Cl4
2508.88
monoclinic
C2/c
29.0161(4)
26.7506(3)
16.0948(2)
90
108.0286(8)
90
11879.4(3)
4
1.403
C215H250Cl2La4O40
4100.70
triclinic
C104H121Tb2O20Cl
2044.30
monoclinic
P21/c
13.94790(10)
26.9161(3)
24.7997(2)
90
100.5081(4)
90
9154.24(14)
4
1.483
space group
˚
P1
a/A
14.5792(2)
17.1037(2)
22.3594(3)
109.0739(5)
98.7864(6)
107.3747(5)
4831.39(11)
2
1.409
0.970
2122
1.36 to 25.00
0.0638
˚
b/A
˚
c/A
R/deg
β/deg
γ/deg
˚
V/A
Z
Dc/g cm-1
μ/mm-1
F(000)
θ range/deg
Rint
1.871
5064
1.06 to 25.00
0.0794
1.634
4208
1.51 to 25.00
0.1151
final R indices [I > 2σ(I)] R1 = 0.0687, wR2 = 0.1878 R1 = 0.0700, wR2 = 0.1713 R1 = 0.0622, wR2 = 0.1831 R1 = 0.0787, wR2 = 0.2179
GOF 0.997 1.196 1.050 1.092
rings have also led to somewhat large thermal ellipsoids; however
this is common with such ligands, and further constraints would
not give a realistic model of the complex.
Crystallographic data (excluding structure factors) for the struc-
tures reported in this paper have been deposited with the Cam-
bridge Crystallographic Data Centre as supplementary numbers
763516-763519. Copies of the data can be obtained free of charge
on application to CCDC, 12 Union Road, Cambridge, CB2 1EZ,
U.K. (fax: þ44 (0) 1223 336033; e-mail: deposit@ccdc.cam.ac.uk).
Acknowledgment. We gratefully thank Dr. Boujemaa
Moubaraki for assistance with the magnetism measurements
and acknowledge financial support from the Australian Re-
search Council and Monash University.
Supporting Information Available: Assignment of charged
species observed for clusters 5-9, crystallographic data for 5,
and magnetic measurements for 7. This material is available free
of charge via the Internet at http://pubs.acs.org.