Expanding the series of [RE2Ca(OQ)8] structures: New heterobimetallic rare earth/alkaline earth 8-quinolinolate complexes

Article abstract of DOI:10.1002/zaac.201200138

A series of heterobimetallic complexes [RE₂Ca(OQ) ₈]·nHOQ (RE = Sm, Gd, Tb, Ho, Tm, Yb, Lu, Y, Sc) and the isostructural [Gd₂Mg(OQ)₈] were synthesised and structurally characterised. They were mainly obtained after direct reactions of the elemental rare earth metals with calcium metal in the presence of 8-hydroxyquinoline (HOQ) and a 1,3,5-tri-tert-butyl-benzene (tBuB) flux, and some complexes were synthesised by pseudo solid-state rearrangement reactions between powdered RE(OQ)₃ and AE(OQ)₂ (AE = Mg, Ca) in a 1,2,4,5-tetramethylbenzene (TMB) flux, at elevated temperatures. The linear trinuclear [RE₂Ca(OQ)₈] moieties show a six-coordinate central calcium atom flanked by two eight-coordinate rare earth atoms surrounded by six chelating-bridging OQ and two terminal chelating OQ ligands. The structurally novel [Sc₂Ca(OQ)₈] has a bent Sc-Ca-Sc backbone and exhibits an eight-coordinate central calcium and two seven-coordinate scandium ions.

Full text of DOI:10.1002/zaac.201200138

ARTICLE
DOI: 10.1002/zaac.201200138
Expanding the Series of [RE Ca(OQ) ] Structures: New Heterobimetallic
2
8
Rare Earth/Alkaline Earth 8-Quinolinolate Complexes
[a]
[a,b]
[a]
[a]
Glen B. Deacon, Peter C. Junk,*
Stuart G. Leary, and Aron Urbatsch
Dedicated to Professor Rudolf Hoppe on the Occasion of His 90th Birthday, A True Father of Solid State Chemistry
Keywords: Rare earths; Alkaline earth metals; Metal-organic complexes; Heterobimetallic compounds; X-ray diffraction
Abstract. A series of heterobimetallic complexes [RE
2
Ca(OQ)
RE = Sm, Gd, Tb, Ho, Tm, Yb, Lu, Y, Sc) and the isostructural
Gd Mg(OQ) ] were synthesised and structurally characterised. They calcium atom flanked by two eight-coordinate rare earth atoms sur-
8
]·nHOQ 1,2,4,5-tetramethylbenzene (TMB) flux, at elevated temperatures. The
(
[
linear trinuclear [RE Ca(OQ) ] moieties show a six-coordinate central
2
8
2
8
were mainly obtained after direct reactions of the elemental rare earth
metals with calcium metal in the presence of 8-hydroxyquinoline
rounded by six chelating-bridging OQ and two terminal chelating OQ
ligands. The structurally novel [Sc Ca(OQ) ] has a bent Sc-Ca-Sc
2
8
(
HOQ) and a 1,3,5-tri-tert-butyl-benzene (tBuB) flux, and some com-
backbone and exhibits an eight-coordinate central calcium and two
seven-coordinate scandium ions.
plexes were synthesised by pseudo solid-state rearrangement reactions
3 2
between powdered RE(OQ) and AE(OQ) (AE = Mg, Ca) in a
Introduction
luminescence applications and has also provided crystallisable
materials.[
8]
Structures of insoluble lanthanoid metal 8-quinolinolates
OQ) have long been elusive, despite their use in quantitative
To meet the challenge of obtaining rare earth/main group
and rare earth/transition metal heterobimetallic complexes of
the unsubstituted 8-quinolinolate and 8-quinaldinolate (MQ)
ligands as structurally characterisable single crystals, we have
devised two pseudo-solid state synthetic approaches. Firstly,
the direct reaction of neodymium and calcium metals in the
presence of HOQ in the flux 1,3,5-tri-tert-butylbenzene (tBuB)
(
[
1]
analysis for over 100 years. The first two structures of the
known simple homoleptic lanthanoid ‘Ln(OQ) ’ compounds,
sometimes represented as six coordinate monomers[ have
3
2]
only recently been determined to have the trinuclear form
[3]
[
Ln (OQ) ] (Ln = Ho, Er). Closely related heteroleptic
3 9
trinuclear
rare
earth
OQЈ
complexes
include
[
4]
at elevated temperatures gave [Nd
2
Ca(OQ)
yield.[ Secondly, rearrangement reactions between powdered
mixtures of ‘Ln(OQ) ’ and ‘Ca/Co(OQ) ’ in the flux 1,2,4,5-
tetramethylbenzene (TMB) at elevated temperatures yielded
8
] (1a) in low
[
Yb (OQ) (OAc)]·3CHCl , NH [Er (OQ) ]Cl(OH)·4(1,4-di-
3
8
3
4
3
8
9]
[5]
oxane), [Er (ClOQ) (OAc)]·6CHCl (ClOQ = 5-chloro-8-
3
8
3
quinolinolate)[5]
[6]
3
2
and [La (MQ) (NO )(HMQ)]·4MeOH
3 8 3
(MQ = 2-methyl-8-quinolinolate/8-quinaldinolate). These
[10]
[
Eu Ca(OQ) ] (1b) and [LaCo (OQ) ].
The last method
2
8
2
7
complexes potentially have desired properties such as
luminescence, which, in the case of the [Er (OQ) ] and
was also successfully used with 8-quinaldinolate reagents and
gave a wide range of structurally diverse homoleptic heterobi-
3
9
[
Yb(5,7-ClOQ) (H-5,7-ClOQ) Cl] (5,7-ClOQ = 5,7-dichloro-
2 2
metallic complexes, such as [Ln Mg(MQ) ] (Ln = Eu, Gd, Tb,
8-quinolinolate) complexes, has led to investigations relevant
2
8
Er) and [Eu Ba(MQ) ]·2TMB usually in low yields, and also
to infrared based communication technology and optical am-
3
11
plifiers.[
3b, 7]
Solubility and hence the capacity to achieve
3
7
3
gave the heteroleptic carbonato species [Ln (OQ) CO ] (Ln =
structurally characterisable compounds, is enhanced both by Eu, Er).[ The versatility of the synthetic approach was fur-
11]
halogen substituents in OQ and by formation of heteroleptic ther demonstrated by the isolation of polymeric alkali/lan-
complexes.[
3–7]
More elaborate functionalisation, especially in- thanoid heterobimetallic coordination polymers [AMLn(Q) ]
4 n
corporating other donors, has been used in conjunction with (Q = OQ: AM = Li, Ln = Tb, Ho, Er; AM = K, Ln = Er; Q =
MQ: AM = Rb; Ln = Tb, Er) and the structurally different
*
Prof. Dr. P. C. Junk
[12]
discrete alkali/lanthanoid [KYb (MQ) ] complex.
In a vari-
alloy with HOQ
at Ͼ190 C gave [LaNi (OQ) ]. We now report the synthesis
2
7
E-Mail: peter.junk@monash.edu; peter.junk@jcu.edu.au
[
[
a] School of Chemistry
Box 23
ant of the first method, reaction of the LaNi
5
o
[13]
2
7
Monash University
and extension of the [Ln Ca(OQ) ] series, to the smaller/heav-
ier rare earths including the first heterobimetallic scandium/
calcium OQ species, [Sc Ca(OQ) ], which has a structure quite
Clayton, VIC 3800, Australia
b] Present address: School of Pharmacy and
Molecular Sciences
2
8
2
8
James Cook University
Townsville, QLD 4811, Australia
different from the other [Ln Ca(OQ) ] complexes.
2
8
Z. Anorg. Allg. Chem. 2012, 638, (᭿), 1–8
© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
1

G. B. Deacon, P. C. Junk, S. G. Leary, A. Urbatsch
ARTICLE
Results and Discussion
ally dominated by the features of the OQ ligand, solvation by
HOQ having little effect. However, the solvated complexes
5·2HOQ, 6·2HOQ and 8·2HOQ show a strong absorption at
Synthesis
3
524/3423 cm–1 attributable to ν(OH) of the HOQ of crystalli-
Rare earth metal filings and pieces of calcium metal in the
presence of 8-hydroxyquinoline (HOQ) and an inert flux
sation. A similar band for 3 (shown to be unsolvated by X-
ray crystallography) suggests that the bulk single crystals also
contained 3·2HOQ. Low crystalline yields, and difficulties in
removing traces of powdered metal (eq. (1)) or reactants (eq.
(1,3,5-tri-tert-butylbenzene, tBuB) and a little mercury metal
(to clean and amalgamate/activate the metal surface) in an
evacuated thick glass tube at 130–190 °C gave a range of het-
erobimetallic complexes of the form [RE Ca(OQ) ]. High
melting (Ͼ360 °C) yellow single crystals of [RE Ca(OQ)
(2)) precluded obtaining satisfactory samples for microanaly-
2
8
sis. In several cases, semi-quantitative Ln:Ca ratios on bulk
crystals were obtained by EDAX and were found to be
2
8]
; RE = Ho, 5, Tm, 6, Lu, 8; n = 2) were handpicked from a
red glassy solid after reaction according to Equation (1) in low
·nHOQ (RE = Sc, 10, Sm, 2, Gd, 3; n = 0; RE = Y, 11; n =
2.0:1.1–1.3, approximating to the single crystal composition.
1
yield (3–5%). The amorphous red substance is, as previously Structural Discussion
shown by EDX measurements, mainly a calcium 8-quinolinol-
[
5
[
RE Ca(OQ) ]·nHOQ (RE = Sm, 2, Gd, 3, Tb, 4, Ho,
2 8
·2HOQ, Tm, 6·2HOQ, Yb, 7, Lu, 8·2HOQ) and
Gd Mg(OQ) ] (9)
2 8
ate species of unknown composition.[ Its insolubility in com-
mon laboratory solvents and intimate mixing with residual
metal makes isolation, purification and some characterisation
difficult.
9]
The linear trinuclear complexes are isostructural with
[8]
[Nd Ca(OQ) ]. The centrosymmetric structures possess two
2 8
peripheral rare earth atoms and are symmetry-related around
the central calcium atom, which is positioned on the inversion
centre (Figure 1, Table 1, Table 2). Each rare earth ion pos-
sesses one terminal chelating (N, O) OQ and three chelating-
bridging (N, O) OQ ligands, giving overall eight coordination
Rearrangement reactions between preformed ‘RE(OQ) ’ and and distorted dodecahedral stereochemistry. These ligands
3
‘
AE(OQ) ’ (AE = Mg, Ca) powders in a 1,2,4,5-tetrameth- bridge through their oxygen atoms to the central calcium atom
2
ylbenzene (TMB) flux at elevated temperatures according to in a distorted octahedral arrangement. In [Gd Mg(OQ) ] (9),
2
8
[11]
Equation (2) produced the isostructural [RE AE(QO) ] (AE = which is isotypic with [Eu Mg(OQ) ],
the smaller magne-
2
8
2
8
Mg; RE = Gd, 9; AE = Ca; RE = Tb, 4, Yb, 7) complexes. sium atom leads to the whole complex being slightly bent
The crystals were handpicked from the bulk residual powder, (Gd-Mg-Gd 176.60(2)°), and the entire complex is crystallo-
which, as previously shown by PXRD measurements, usually graphically unique. Bond lengths in complex 9 are very similar
also contains the complex, albeit as a microcrystalline mate- to those of the europium analogue[ and are not discussed in
11]
[
9–11]
rial.
Although the yields of single crystals by both synthe- detail. The holmium (5·2HOQ), thulium (6·2HOQ) and lute-
ses were very low, the amounts were sufficient for structure tium (8·2HOQ) derivatives are solvated by two molecules of
determinations in all cases (below), thus fulfilling our principal HOQ, in a hydrogen-bonded dimer (Figure 1(b)).
objective. Some syntheses by reaction (1) were carried out
with a 2Ln:Ca g atom ratio, but 3 and 5 were obtained with complexes can now be extended to the smaller/heavier rare
Observations on bond lengths previously made for 1a, 1b
near equal amounts of each metal, hence the [RE Ca(OQ) ] earths (Table 1, Table 2). As expected, Ca–O bond lengths are
2
8
composition/structure is evidently favoured. Reactions accord- little affected by the change of the lanthanoid metal and they
ing to eq. (1) produced both solvated (by 2 HOQ for 5, 6, 8 range from 2.287(5)–2.376(3) Å across the series. Ln–N dis-
and by 1 HOQ for 11) and unsolvated complexes. Although tances show little variation whether the ligands are terminal or
unsolvated 2 and 3 were obtained from reactions with a large bridging and the average Ln–N distance follows the lanthanoid
excess of Ln/Ca over HOQ, the structurally different contraction.[ Terminal Ln–O bond lengths are shorter (by
14]
[
Sc Ca(OQ) ] was obtained unsolvated despite use of a rela- about 0.09 Å) than their bridging counterparts and both also
2
8
tively higher amount of HOQ. Most reactions by (1) were car- follow the lanthanoid contraction.
ried out with an excess of the free metal reagents. In the syn-
Because of the poor quality of the crystals of
theses by (2) no products solvated by the flux were obtained, [Y Ca(OQ) ]·HOQ (11·HOQ), the structure only establishes
2
8
whereas the flux TMB was found in the lattice of structures of the connectivity as isostructural with Ln analogues and bond
the related MQ complexes [RE Mg(MQ) ]·1/3TMB (RE = Eu, lengths are not discussed. A mono HOQ solvate has also been
2
8
Gd, Tb).[ We have now isolated a sufficient number of the isolated for Nd (1a·HOQ) in addition to the unsolvated com-
11]
lanthanoid series of linear trimetallic [Ln Ca(OQ) ] com- plex (1a).[
9]
2
8
plexes, to give a more complete structural picture. The rare
earth metals scandium and yttrium also adopt the same stoichi-
ometry. Crystalline materials were identified by single crystal
X-ray diffractometry and infrared spectroscopy. All infrared
[
Sc Ca(OQ) ] (10)
2 8
The scandium derivative 10, despite possessing the same
–
1
spectra were essentially identical at 1750–650 cm , being tot- stoichiometry, displays large structural differences compared
2
www.zaac.wiley-vch.de © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Z. Anorg. Allg. Chem. 2012, 1–8

New Heterobimetallic Rare Earth/Alkaline Earth 8-Quinolinolate Complexes
Figure 1. Crystal structure of (a) [Tm
7), Lu (8·2HOQ)) and; (b) depicted with lattice HOQ molecules. Thermal ellipsoids are set at 50% probability. All hydrogen atoms are omitted
for clarity. The atom denoted # is generated by the symmetry operator 1–x, 2–y, 1–z.
2 8 2 8
Ca(OQ) ]·2HOQ (6·2HOQ), representative of [Ln Ca(OQ) ] (Sm (2), Gd (3), Tb (4), Ho (5·2HOQ), Yb
(
Table 1. Selected Bond lengths /Å for complexes 2–8 and for complexes [Ln
2
Ca(OQ)
] (Ln = Nd,[9] Eu[10]).
8
[Nd
2
CaOQ
8
] (1a)
2
[Eu
2
CaOQ ] (1b)
8
3
4
Ln(1)-O(1A)
Ln(1)-O(1B)
Ln(1)-O(1C)
Ln(1)-O(1D)
Ln(1)-N(1A)
Ln(1)-N(1B)
Ln(1)-N(1C)
Ln(1)-N(1D)
Ca(1)-O(1B)
Ca(1)-O(1C)
Ca(1)-O(1D)
Ln(1)-Ca(1)
2.335(4)
2.437(3)
2.431(3)
2.419(3)
2.602(4)
2.592(3)
2.610(4)
2.604(4)
2.321(3)
2.376(3)
2.309(3)
3.4505(11)
2.321(6)
2.410(5)
2.403(6)
2.395(5)
2.568(7)
2.573(6)
2.584(7)
2.581(7)
2.323(5)
2.369(5)
2.305(6)
3.4362(12)
2.300(3)
2.402(3)
2.382(2)
2.386(3)
2.549(4)
2.556(3)
2.557(4)
2.564(4)
2.323(3)
2.303(3)
2.376(3)
3.433(1)
2.299(3)
2.385(3)
2.376(3)
2.371(3)
2.532(4)
2.545(3)
2.560(4)
2.548(4)
2.322(3)
2.376(3)
2.307(3)
3.4282(11)
2.264(4)
2.371(4)
2.355(4)
2.365(4)
2.527(5)
2.533(4)
2.533(5)
2.553(5)
2.321(4)
2.297(4)
2.367(4)
3.4254(16)
5·2HOQ
6·2HOQ
7
8·2HOQ
Ln(1)-O(1A)
Ln(1)-O(1B)
Ln(1)-O(1C)
Ln(1)-O(1D)
Ln(1)-N(1A)
Ln(1)-N(1B)
Ln(1)-N(1C)
Ln(1)-N(1D)
Ca(1)-O(1B)
Ca(1)-O(1C)
Ca(1)-O(1D)
Ln(1)-Ca(1)
2.231(2)
2.348(2)
2.353(2)
2.327(2)
2.494(3)
2.524(3)
2.504(3)
2.516(3)
2.322(2)
2.340(2)
2.341(2)
3.3936(9)
2.208(3)
2.328(3)
2.333(3)
2.312(3)
2.472(4)
2.505(4)
2.485(4)
2.495(4)
2.318(3)
2.336(3)
2.334(3)
3.3818(9)
2.226(6)
2.317(6)
2.291(5)
2.314(5)
2.457(8)
2.493(6)
2.498(7)
2.476(7)
2.298(5)
2.368(6)
2.287(5)
3.3985(11)
2.200(3)
2.305(3)
2.325(2)
2.284(2)
2.451(3)
2.492(3)
2.467(3)
2.475(3)
2.320(3)
2.329(2)
2.337(3)
3.3741(9)
with the other complexes presented herein. It crystallises in the allows seven-coordination, whereas the larger ionic radius of
monoclinic space group P2 /n, whereas the preceding lan- the central Ca2+ (1.12 Å) allows eight-coordination. The pe-
1
¯
thanoid derivatives crystallise in the triclinic space group P1 ripheral scandium atoms each possess one terminal chelating,
Table 3, Table 4, Table 5). The calcium ion is not positioned two chelating-bridging (N,O) OQ ligands, and one OQ ligand
(
on a centre of inversion, whilst all the metal ions are now bound by oxygen to scandium, but chelating (O,N) to calcium,
unique and part of the asymmetric unit. The coordination num- as opposed to one terminal and three chelating-bridging OQ
bers for the metals are different in this complex (Figure 2). ligands in the preceding complexes. Eight-coordination for cal-
The small ionic radius of the rare earth metal scandium (0.807 cium is achieved by the four oxygen atoms from four adjacent
3
+
Å for Sc with CN = 7, interpolated from data of [14]) only chelating-bridging OQ ligands, and by the two oxygen and two
Z. Anorg. Allg. Chem. 2012, 1–8
© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.zaac.wiley-vch.de 3

G. B. Deacon, P. C. Junk, S. G. Leary, A. Urbatsch
ARTICLE
Table 2. Selected Bond lengths /Å for complexes 9 and 10.
83.82(12)°). The seven-coordinate scandium atom has a
capped trigonal anti-prismatic geometry with the three bridg-
ing oxygen atoms filling one face of the polyhedron whilst
O(1A), N(1A) and N(1C) fill the other face and N(1B) caps
the metal atom (Figure 2).
9
10
Gd(1)-O(1A)
Gd(1)-O(1B)
Gd(1)-O(1C)
Gd(1)-O(1D)
Gd(2)-O(1E)
Gd(2)-O(1F)
Gd(2)-O(1G)
Gd(2)-O(1H)
Gd(1)-N(1A)
Gd(1)-N(1B)
Gd(1)-N(1C)
Gd(1)-N(1D)
Gd(1)-N(1E)
Gd(2)-N(1F)
Gd2)-N(1G)
Gd(2)-N(1H)
Mg(1)-O(1B)
Mg(1)-O(1C)
Mg(1)-O(1D)
Mg(1)-O(1E)
Mg(1)-O(1F)
Mg(1)-O(1G)
Gd(1)-Mg(1)
Gd(2)-Mg(1)
2.2941(18)
2.3603(15)
2.3699(16)
2.3536(19)
2.3794(19)
2.3765(16)
2.3419(16)
2.2973(18)
2.559(2)
Sc(1)-O(1A)
Sc(1)-O(1B)
Sc(1)-O(1C)
Sc(1)-O(1D)
Sc(2)-O(1E)
Sc(2)-O(1F)
Sc(2)-O(1G)
Sc(2)-O(1H)
Sc(1)-N(1A)
Sc(1)-N(1B)
Sc(1)-N(1C)
Sc(2)-N(1E)
Sc(2)-N(1F)
Sc(2)-N(1G)
Ca(1)-O(1B)
Ca(1)-O(1C)
Ca(1)-O(1D)
Ca(1)-O(1E)
Ca(1)-O(1G)
Ca(1)-O(1H)
Ca(1)-N(1D)
Ca(1)-N(1H)
Sc(1)-Ca(1)
Sc(2)-Ca(1)
2.072(3)
2.174(3)
2.155(3)
2.048(3)
2.136(3)
2.054(3)
2.157(3)
2.093(3)
2.460(4)
2.421(4)
2.278(4)
2.330(4)
2.355(4)
2.431(4)
2.423(3)
2.417(3)
2.535(3)
2.438(3)
2.359(3)
2.548(3)
2.566(4)
2.515(4)
3.3416(14)
3.3441(15)
The larger ionic radius of eight-coordinate calcium
14]
(
1.12 Å)[ leads to a general lengthening of the bridging
Ca–O bonds when compared with the other heterobimetallic
complexes in which calcium is six coordinate. The average
Ca–O bond length in [Nd Ca(OQ) ] (Ca six-coordinate) is
2
8
2.543(2)
2.550(2)
2.335 Å, whereas in 10 (Ca eight-coordinate) it is 2.453 Å,
which corresponds well with the change in ionic radius
2.5670(18)
2.5412(18)
2.5306(19)
2.575(2)
2.5313(19)
2.0761(18)
2.0633(17)
2.1078(16)
2.1029(16)
2.0734(17)
2.0623(19)
3.2054(13)
3.2070(13)
(0.12 Å) of calcium from the change in coordination number.
However, Ca(1)–O(1D) and Ca(1)–O(1H) (oxygen atoms from
the two OQ ligands that chelate to calcium) are unusually long,
2.535(3) and 2.548(3) Å respectively. The remaining four
Ca(1)–O bond lengths of the bridging oxygen atoms are much
shorter and are only 2.409 Å (ave). As with Ca(1), Sc(1) shows
large variation in some of the bond lengths. The Sc(1)–N(1D)
bond is considerably shorter (by about 0.15–0.20 Å), than
Sc(1)–N(1A) and Sc(1)–N(1B) (2.460(4) and 2.421(4) Å
respectively). Previous crystallographically characterised scan-
2
1
1
dium quinolinolate complexes are [Sc(η -MQ) (η -MQ)(η -
2
[15]
HMQ)]·2H O,
and the dimeric [Sc(OQ) ] and the discrete
3 2
Sc(2NH Q) ] (2NH Q = 2-amino-8-quinolinolate).
2
[16]
[
2 3 2
nitrogen atoms of two chelating-bridging OQ ligands. There-
fore, two OQ ligands that formerly were coordinated to the
peripheral rare earth atoms in 1–9, have flipped by 180° and
the nitrogen atoms of these are now coordinated to the alkaline
earth metal.
Conclusions
We have synthesised a range of linear [Ln Ca(OQ) ] com-
2
8
The structure is bent (Sc–Ca–Sc angle 145.29(4)°). The cal- plexes now extending the sizes of the lanthanoid series from
cium ion adopts a 4,4-bicapped trigonal anti-prismatic geome- samarium to lutetium (and Y). The complexes are isostructural
try with the two chelating ligands (D and H) being bound to and their bond lengths follow the lanthanoid contraction. The
the calcium in a cis arrangement (N(1D)–Ca(1)–N(1H) is structurally new, bent [Sc Ca(OQ) ] (10) is the first structur-
2
8
Table 3. Crystallographic data for complexes 5·2HOQ, 6·2HOQ and 8·2HOQ.
Compound reference
5·2HOQ
62CaHo
6·2HOQ
8·2HOQ
2 10 10
62CaLu N O
Chemical formula
C
90
H
2
N
10
O
10
C
90
H62CaN10
O10Tm
2
C
90
H
Formula Mass
Crystal system
Space group
1813.44
triclinic
P1
1821.44
triclinic
P1
1833.52
triclinic
P1
¯
¯
¯
a /Å
b /Å
c /Å
α /°
β /°
γ /°
11.442(2)
12.448(3)
14.348(3)
96.62(3)
96.45(3)
112.47(3)
1848.3(6)
173(1)
11.445(2)
12.438(3)
14.306(3)
96.54(3)
96.51(3)
112.56(3)
1840.9(6)
123(1)
11.433(2)
12.431(3)
14.287(3)
96.63(3)
96.52(3)
112.64(3)
1833.7(6)
123(1)
Unit cell volume/Å3
Temperature/K
No. of formula units per unit cell, Z
No. of reflections measured
No. of independent reflections
1
1
1
28998
8438
31149
8410
14963
8124
R
int
0.0571
0.0320
0.0808
0.0462
0.0896
0.772
0.0659
0.0400
0.0870
0.0563
0.0925
1.057
0.0426
0.0334
0.0732
0.0444
0.0771
1.018
Final R
Final wR(F ) values (I Ͼ 2σ(I))
Final R values (all data)
1
values (I Ͼ 2σ(I))
2
1
2
Final wR(F ) values (all data)
Goodness of fit on F2
4
www.zaac.wiley-vch.de
© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Z. Anorg. Allg. Chem. 2012, 1–8

New Heterobimetallic Rare Earth/Alkaline Earth 8-Quinolinolate Complexes
Table 4. Crystallographic data for complexes 2–4.
Compound reference
2
3
4
Chemical formula
C
72
H48CaN
8
O
8
Sm
2
C
72
H48CaGd
2
N
8
O
8
72 8 8 2
C H48CaN O Tb
Formula Mass
Crystal system
Space group
1493.96
triclinic
P1
1507.76
triclinic
P1
1511.10
triclinic
P1
¯
¯
¯
a /Å
b /Å
c /Å
α /°
β /°
γ /°
11.308(2)
12.438(3)
13.885(3)
116.56(3)
95.57(3)
109.71(3)
1571.5(5)
123(1)
11.317(2)
12.413(3)
13.855(3)
116.57(3)
95.57(3)
109.74(3)
1565.5(5)
123(1)
11.344(2)
12.389(3)
13.852(3)
63.44(3)
66.29(3)
70.11(3)
1563.6(5)
123(1)
1
Unit cell volume/Å3
Temperature/K
No. of formula units per unit cell, Z
No. of reflections measured
No. of independent reflections
1
1
19462
6976
24093
7150
18607
6962
R
int
0.1284
0.0740
0.1337
0.1574
0.1628
1.002
0.0886
0.0454
0.1021
0.0574
0.1082
1.018
0.0850
0.0584
0.1445
0.0684
0.1522
1.039
Final R
Final wR(F ) values (I Ͼ 2σ(I))
Final R values (all data)
1
values (I Ͼ 2σ(I))
2
1
2
Final wR(F ) values (all data)
Goodness of fit on F2
Table 5. Crystallographic data for complexes 7–11.
Compound reference
7
9
10
11·HOQ
9 9 2
54CaN O Y
Chemical formula
C
72
H48CaN
8
O
8
Yb
2
C
72
H48Gd
2
MgN
8
O
8
C
72
H48CaN
8
O
8
Sc
2
C
81
H
Formula Mass
Crystal system
Space group
1539.34
triclinic
P1
1491.99
triclinic
P1
1283.18
monoclinic
1533.23
monoclinic
P2 /n
1
¯
¯
P2
1
/n
a /Å
b /Å
c /Å
α /°
β /°
γ /°
11.389(2)
12.303(3)
13.794(3)
116.27(3)
96.09(3)
110.21(3)
1547.4(5)
123(1)
12.457(3)
13.651(3)
18.496(4)
94.89(3)
95.56(3)
100.55(3)
3060.4(11)
123(1)
2
44170
13868
0.0288
0.0232
0.0512
0.0310
0.0549
1.055
12.950(3)
21.695(4)
21.361(4)
90
93.49(3)
90
5991(2)
123(1)
4
80197
13722
0.2933
0.0823
0.1236
0.2817
0.1750
0.971
15.310(3)
9.974(2)
23.513(5)
90
108.98(3)
90
3395.2(12)
123(1)
2
35098
7670
0.4450
0.0963
0.1139
0.3496
0.1707
0.945
Unit cell volume/Å3
Temperature/K
No. of formula units per unit cell, Z
No. of reflections measured
No. of independent reflections
1
27562
7087
R
int
0.1826
0.0684
0.1252
0.1524
0.1542
1.025
Final R
Final wR(F ) values (I Ͼ 2σ(I))
Final R values (all data)
1
values (I Ͼ 2σ(I))
2
1
2
Final wR(F ) values (all data)
Goodness of fit on F2
ally characterised heterobimetallic OQ complex incorporating
the small scandium metal. Compared (but see the homomet-
[16]
allic [Sc (OQ) ] ) with the [Ln Ca(OQ) ] complexes, the
2
6
2
8
metal ions in 10 exhibit a change in coordination number from
–9, with the calcium being eight-coordinate and scandium
1
ions being seven-coordinate. Reactions of the elemental metals
in the presence of HOQ and an inert flux (tBuB), leads to
crystallisation of above complexes, in low isolated yield. The
main product of the direct metal reactions is an amorphous
red substance of unknown composition. The pseudo solid-state
approach involving preformed M(OQ) powders in TMB is
x
becoming a general route to homoleptic heterobimetallic lan-
thanoid complexes,[
10–12]
albeit also in low yield. Despite the
low yields, the pseudo solid-state syntheses provide single
crystals suitable for structural characterisation of homoleptic
2 8
Figure 2. Crystal structure of [Sc Ca(OQ) ] (10). Thermal ellipsoids
are set at 50% probability. All hydrogen atoms are omitted for clarity. heterobimetallic OQ complexes.
Z. Anorg. Allg. Chem. 2012, 1–8
© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.zaac.wiley-vch.de
5

G. B. Deacon, P. C. Junk, S. G. Leary, A. Urbatsch
ARTICLE
and Hg (8 drops) at 140 °C for 3 d. Crystal yield: 0.05 g, 3%; m.p.
Experimental Section
–
1
Ͼ 360 °C, IR (Nujol mull, cm ): 3423s, 1595s, 1560s, 1490s, 1415s,
274vs, 1218s, 1121sh, 1103vs, 1055w, 820vs, 785vs, 740vs, 728vs.
Microprobe- Ho:Ca = 2.0:1.3.
Rare earth metal (99.9%) was from Rhone Poulenc, calcium (turnings,
9
1
9%), 1,3,5-tri-tert-butylbenzene (tBuB) and 1,2,4,5-tetramethylbenz-
ene (TMB) were from Aldrich. 8-Hydroxyquinoline (Ͼ99%) was from
Merck and all were used without further purification. Precursor [Tm
RE(OQ) ’ and ‘AE(OQ) ’ metal 8-quinolinolate complexes were pre- g, 0.75 mmol), HOQ (0.80 g, 5.52 mmol), tBuB (0.30 g, 1.22 mmol)
pared by mixing aqueous solutions of the metal chloride (either as and Hg (5 drops) at 140 °C for 3 d. Crystal yield: 0.05 g, 4%; m.p.
2
8
Ca(OQ) ]·2HOQ (6·2HOQ): Tm (0.20 g, 1.18 mmol), Ca (0.03
‘
3
2
–
1
purchased or from dissolution of the metal oxide in hydrochloric acid) Ͼ 360 °C, IR (Nujol mull, cm ): 3424w, 1593s, 1561m, 1488s,
and a stoichiometric amount of Na(OQ) (prepared by stoichiometric 1413m, 1383s, 1272vs, 1215m, 1105vs, 1053w, 819vs, 783s, 742vs,
reaction of HOQ with NaOH in EtOH and evaporation thereof), fil-
tration and subsequent drying of the precipitated complex. IR spectra
were recorded with a Perkin Elmer 1600 FTIR spectrophotometer as
nujol mulls on NaCl plates. EDX measurements were performed in
ultra-high vacuum with a Joel JSM 840A scanning microscope.
725s. Microprobe- Tm:Ca = 2.0:1.1.
[Yb
2 8 3 2
Ca(OQ) ] (7): Yb(OQ) (0.30 g, 0.50 mmol), Ca(OQ) (0.08 g,
0.25 mmol) and TMB (1.50 g, 11.17 mmol) at 210 °C for 20 d. Crystal
–
1
yield: 0.05 g, 12%; IR (Nujol mull, cm ): 1720w, 1599m, 1569s,
318m, 1280m, 1227w, 1168w, 1105s, 1029w, 960w, 860w, 821s,
807m, 782s, 643w.
1
Direct metal reactions: Synthesis of the complexes 2, 5·2HOQ,
6
·2HOQ, 8·2HOQ and 10 was achieved by reaction of freshly filed
RE metal (0.10–0.90 g) with pieces of calcium metal (0.025–0.16 g) [Lu
in the presence of HOQ (0.2–1.0 g) in the inert flux tBuB (0.3–1.0 g)
g, 0.63 mmol), HOQ (0.80 g, 5.52 mmol), tBuB (0.30 g, 1.22 mmol)
and a few drops of mercury in a thick-walled evacuated glass tube for and Hg (9 drops) at 190 °C for 3 d. Crystal yield: 0.04 g, 3%; m.p.
2
8
Ca(OQ) ]·2HOQ (8·2HOQ): Lu (0.20 g, 1.14 mmol), Ca (0.025
–
1
several days at temperatures ranging from 130–190 °C. The glass ves-
sels were charged under an inert atmosphere. The tBuB was removed 1280vs, 1220s, 1107vs, 1050w, 822m, 787m, 742m, 730s. Microprobe-
Ͼ 360 °C, IR (Nujol mull, cm ): 3424s, 1565s, 1488m, 1418s,
by sublimation and removal of the products from the tubes was con-
ducted in a Braun Glove Box where they were placed under thick
hydrocarbon oil and characterised by low temperature X-Ray crystal-
lography. The crystals and the predominantly formed red glassy solids
were separated by hand-picking from the hydrocarbon oil and washed
with hexane and allowed to dry before being characterised by EDX
and IR spectroscopy.
Lu:Ca = 2.0:1.1.
[Gd
2 8 3 2
Mg(OQ) ] (9): Gd(OQ) (0.29 g, 0.50 mmol), Mg(OQ) (0.07 g,
0.25 mmol) and TMB (1.50 g, 11.17 mmol) at 210 °C for 20 d. Crystal
–
1
yield: 0.06 g, 17%; IR (Nujol mull, cm ): 1720w, 1600m, 1568s,
1
8
317m, 1280m, 1228w, 1168w, 1105s, 1029w, 961w, 862w, 823s,
07m, 783s, 643w.
[
2 8
Sc Ca(OQ) ] (10): Sc (0.10 g, 2.22 mmol), Ca (0.05 g, 1.25 mmol),
Rearrangement reactions: Synthesis for complexes 3, 4, 7 and 9 were
achieved by heating ca. 0.50 g of the powdered reaction mixture
HOQ (0.80 g, 5.52 mmol), tBuB (0.30 g, 1.22 mmol) and Hg (7 drops)
at 190 °C for 3 d. Crystal yield: 0.09 g, 10%; m.p. Ͼ 360 °C, IR (Nujol
3 2
(Ln(OQ) and AE(OQ) ), with the desired stoichiometry of the precur-
–
1
mull, cm ): 1597s, 1565s, 1493s, 1425s, 1278vs, 1226s, 1106m, 820s,
87s, 742s, 728s. Microprobe- Sc:Ca = 2.00:1.11.
sor compounds and 1.5 g flux (1,2,4,5-tetramethylbenzene (TMB)) in
a sealed and evacuated thick walled glass tube above 200 °C for sev-
eral days. After visual examination confirmed that a reaction had oc-
curred, the flux was removed from the reaction mixture by sublimation
in an open-end oven at 150 °C for 2–4 hours. The cooled tubes were
opened in air and crystalline material (yellow-orange crystals unless
otherwise indicated) was handpicked from the bulk residual powder
and characterised by single X-ray crystallography.
7
[
Y
2
Ca(OQ)
8
]·HOQ (11·HOQ): Y (0.40 g, 4.50 mmol), Ca (0.16 g,
4
.00 mmol), HOQ (1.00 g, 6.90 mmol), tBuB (0.30 g, 1.22 mmol) and
Hg (10 drops) at 150 °C for 2 d. Crystal yield: 0.09 g, 7%; m.p.
Ͼ 360 °C, IR (Nujol mull, cm ): 3423s, 1595s, 1560s, 1490s, 1415s,
1
7
–
1
383s, 1274vs, 1218s, 1121sh, 1103vs, 1055w, 820vs, 785vs, 740vs,
28vs.
2 8
[Sm Ca(OQ) ] (2): Sm (0.90 g, 5.98 mmol), Ca (0.12 g, 2.99 mmol),
HOQ (1.0 g, 6.90 mmol), tBuB (1.00 g, 4.07 mmol) and Hg (7 drops)
at 140 °C for 4 d. Crystal yield: 0.06 g, 5%; m.p. Ͼ 360 °C, IR (Nujol
Crystallography
–1
mull, cm ): 1599s, 1566s, 1490s, 1426s, 1383s, 1275vs, 1228s,
110vs, 982w, 819vs, 785vs, 746vs, 728vs. Microprobe- Sm:Ca =
.0:1.3
Low-temperature single-crystal X-ray diffraction experiments were
performed with a Bruker Apex II KAPPA CCD (only for 9) or an
Enraf Nonius Kappa CCD with Mo-Kα radiation (λ = 0.71073 Å) and
equipped with an Oxford Instruments nitrogen gas cryostream. Single
crystals were mounted on a glass fibre in viscous hydrocarbon oil.
Crystals were quench-cooled to 123(2) K (173(2) K for 5·2HOQ).
Analysis of diffraction data collected with the Bruker Apex II KAPPA
CCD was performed by using SAINT+ within the APEX2 software
1
2
2 8
[Gd Ca(OQ) ] (3): Gd (0.50 g, 3.17 mmol), Ca (0.14 g, 3.50 mmol),
HOQ (0.20 g, 1.38 mmol), tBuB (0.20 g, 0.81 mmol) and Hg (7 drops)
at 170 °C for 4 d. Crystal yield: 0.01 g, 4%; m.p. Ͼ 360 °C, IR (Nujol
–1
mull, cm ): 3417s, 1596s, 1560s, 1495s, 1423m, 1279vs, 1224s,
100vs, 1052w, 820vs, 787vs, 742vs, 730vs. Microprobe- Gd:Ca =
.0:1.3.
1
2
[
17]
package.
by using SADABS.
8 3 2
] (4): Tb(OQ) (0.29 g, 0.50 mmol), Ca(OQ)
(0.08 g, Enraf Nonius Kappa CCD was performed by using DENZO. Empir-
Empirical absorption corrections were applied to all data
[
18]
Analysis of diffraction data collected with the
[
19]
[Tb
2
Ca(OQ)
[
20]
0
.25 mmol) and TMB (1.50 g, 11.17 mmol) at 210 °C for 20 d. Crystal
ical absorption corrections were applied to all data using SORTAV
–1
[19]
[21]
yield: 0.06 g, 16%; IR (Nujol mull, cm ): 1717w, 1596m, 1568s,
within WINGX.
The structures were solved using SHELXS
[
22]
1
8
317m, 1280m, 1223w, 1168w, 1105s, 1032w, 961w, 862w, 823s,
08m, 784s, 642w.
and refined using SHELXL-97
within the graphical interface
[
23]
X-SEED.
Unit cell and refinement data are given in Tables 3–5.
[
Ho
2
Ca(OQ)
8
]·2HOQ (5·2HOQ): Ho (0.50 g, 3.03 mmol), Ca (0.10
CCDC-873184, -873185, -873186, -873187, -873188, -873189,
-873190, -873191, -873192, -873193 contain the supplementary crys-
g, 2.50 mmol), HOQ (1.00 g, 6.89 mmol), tBuB (0.30 g, 1.22 mmol)
6
www.zaac.wiley-vch.de
© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Z. Anorg. Allg. Chem. 2012, 1–8

New Heterobimetallic Rare Earth/Alkaline Earth 8-Quinolinolate Complexes
tallographic data for this paper. These data (excluding structure factors)
can be obtained free of charge from The Cambridge Crystallographic
Data Centre via www.ccdc.cam.ac.uk/data_request/cif.
Bozoklu, C. Marchal, J. Pecaut, D. Imbert, M. Mazzanti, Dalton
Trans. 2010, 39, 9112–9122; e) F. Artizzu, M. L. Mercuri, A.
Serpe, P. Deplano, Coord. Chem. Rev. 2011, 255, 2514–2529.
[
8] a) M. Albrecht, O. Osetska, R. Fröhlich, J. C. G. Bünzli, A. Aeb-
ischer, F. Gumy, J. Hamacek, J. Am. Chem. Soc. 2007, 129,
1
4178–14179; b) M. Albrecht, M. Fiege, O. Osetska, Coord.
Acknowledgments
Chem. Rev. 2008, 252, 812–824; c) M. Albrecht, M. Fiege, P.
Kögerler, M. Speldrich, R. Fröhlich, M. Engeser, Chem. Eur. J.
We are grateful to the Australian Research Council (grant
DP0984775).
2
2
010, 16, 8797–8804; d) M. Albrecht, Z. Anorg. Allg. Chem.
010, 636, 2198–2204; e) M. Albrecht, O. Osetska, Eur. J. Inorg.
Chem. 2010, 4678–4682; f) J.-C. G. Bünzli, C. Piguet, Chem. Soc.
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Received: March 26, 2012
Published Online: ᭿
Z. Anorg. Allg. Chem. 2012, 1–8
© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.zaac.wiley-vch.de
7

G. B. Deacon, P. C. Junk, S. G. Leary, A. Urbatsch
ARTICLE
G. B. Deacon, P. C. Junk,* S. G. Leary, A. Urbatsch ...... 1–8
Expanding the Series of [RE Ca(OQ) ] Structures: New Het-
2
8
erobimetallic Rare Earth/Alkaline Earth 8-Quinolinolate Com-
plexes
8
www.zaac.wiley-vch.de
© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Z. Anorg. Allg. Chem. 2012, 1–8