3,5-Di-tert-butyl-o-benzoquinone complexes of lanthanides

Article abstract of DOI:10.1016/j.jorganchem.2011.10.015

Lanthanide semiquinolates Ln(SQ)₃ (SQ-3,5-di-tert-butyl-o- benzosemiquinone) were prepared by the reactions of Dy, Tm, Yb with 3 equiv of 3,5-di-tert-butyl-o-benzoquinone (Q). Crystallization of thulium product from DME yields structurally characterized cluster Tm₃(SQ) ₄(Cat)₂(QH)(DME)₂ (1) (Cat-3,5-di-tert-butyl- catecholate, QH-o-hydroxyphenolate). The reactions of Q with excess of metal (Sm, Eu, Tm, Yb) afford catecholates Ln₂(Cat)₃. For samarium product Sm₄(Cat)₆(THF)₆ (2) X-ray diffraction study was performed. In the reaction of EuI₂ with Li ₂(Cat) ate-complex EuLi₄(LiI)₂(SQ) ₂(Cat)₂(THF)₆ (3) was isolated. X-ray analysis revealed that a molecule of the complex contains two semiquinone groups, two catecholate ligands, Eu²⁺ cation, four Li⁺ cations and two LiI species bonded by bridging O and I atoms. Catecholates of Eu(II), Sm(II) as well as trivalent Ce, Nd, Gd, and Tb were obtained by treatment of corresponding lanthanide silylamides Ln[N(SiMe₃)₂] _n (n = 2, 3) with the 3,5-di-tert-butyl-catechol. It was established that gadolinium product Gd₄(Cat)₆(THF)₆ (4) is isostructural to samarium complex 2. Terbium catecholate Tb₂(Cat) ₃ in THF solution revealed photoluminescence typical for Tb ³⁺ cation.

Full text of DOI:10.1016/j.jorganchem.2011.10.015

Journal of Organometallic Chemistry 698 (2012) 35e41
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Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
3,5-Di-tert-butyl-o-benzoquinone complexes of lanthanides
*
D.M. Kuzyaev , D.L. Vorozhtsov, N.O. Druzhkov, M.A. Lopatin, E.V. Baranov, A.V. Cherkasov,
G.K. Fukin, G.A. Abakumov, M.N. Bochkarev
G.A. Razuvaev Institute of Organometallic Chemistry of Russian Academy of Sciences, Russian Federation, Tropinina 49, 603950 Nizhny Novgorod, Russian Federation
a r t i c l e i n f o
a b s t r a c t
Article history:
Lanthanide semiquinolates Ln(SQ)3 (SQ-3,5-di-tert-butyl-o-benzosemiquinone) were prepared by the
reactions of Dy, Tm, Yb with 3 equiv of 3,5-di-tert-butyl-o-benzoquinone (Q). Crystallization of thulium
product from DME yields structurally characterized cluster Tm3(SQ)4(Cat)2(QH)(DME)2 (1) (Cat-3,5-di-
tert-butyl-catecholate, QH-o-hydroxyphenolate). The reactions of Q with excess of metal (Sm, Eu, Tm, Yb)
afford catecholates Ln2(Cat)3. For samarium product Sm4(Cat)6(THF)6 (2) X-ray diffraction study was
performed. In the reaction of EuI2 with Li2(Cat) ate-complex EuLi4(LiI)2(SQ)2(Cat)2(THF)6 (3) was isolated.
X-ray analysis revealed that a molecule of the complex contains two semiquinone groups, two cat-
echolate ligands, Eu2þ cation, four Liþ cations and two LiI species bonded by bridging O and I atoms.
Catecholates of Eu(II), Sm(II) as well as trivalent Ce, Nd, Gd, and Tb were obtained by treatment of
corresponding lanthanide silylamides Ln[N(SiMe3)2]n (n ¼ 2, 3) with the 3,5-di-tert-butyl-catechol. It was
established that gadolinium product Gd4(Cat)6(THF)6 (4) is isostructural to samarium complex 2.
Terbium catecholate Tb2(Cat)3 in THF solution revealed photoluminescence typical for Tb3þ cation.
Ó 2011 Elsevier B.V. All rights reserved.
Received 22 June 2011
Received in revised form
17 August 2011
Accepted 6 October 2011
Keywords:
3,5-Di-tert-butyl-o-benzoquinone
Lanthanides
Catecholate
Europium diiodide
Photoluminescence
1. Introduction
tert-butyl-catecholate ligands. Their photoluminescence properties
and molecular structures of some of them were investigated. Unfor-
Quinone complexes of transition and non-transition metals
belong to a number of the well-investigated classes of coordination
compounds [1]. However, in a literature there are only a few
examples of o-quinone complexes of lanthanides. In the paper [2]
complexes of supposed composition Ln(SQ)3 were characterized
by EPR spectroscopy. In other works the catecholates
[Ln(C6H4O2)3]2Na6(H2O)20 (Ln ¼ Gd, Ho) [3] and [Ce(C6H4O2)4]
Na4(H2O)21 [4], heteroleptic complexes Tp2Gd(SQ)(CHCl3)2 [5],
[Tp2Gd2(SQ)4] [6], (TpMe2)2Sm(SQ) [7] (Tp e hydrotris(pyrazol-1-
yl)borate) and catecholate-iodide [3,6-(t-Bu)2C6H2O2]TmI2(DME)2
[8] were considered. At the same time, broad coordination ability of
lanthanides, on the one hand, and existence of quinones in three
states (neutral ligand, radical-anion and dianion), on the other
hand, give the grounds to assume a big variety of arrangement of
quinone derivatives of rare earth metals.
tunately, electroluminescent properties of the products remained not
investigated because of their high air sensitivity and low thermal
stability.
2. Results and discussion
The complexes of trivalent lanthanides with benzoquinone Q
were prepared by interaction of Q with respective metals or by
treatment of silylamide complexes Ln[N(SiMe3)2]3 with 3,5-di-tert-
butyl-catechol. The latter pathway was applied as well for prepa-
ration of Sm(II) and Eu(II) complexes. Alternatively, the Eu(II)
derivative has been obtained by the metathesis reaction of EuI2
with lithium catecholate Li2Cat.
Besides, presence of system of conjugated bonds in the [OCCO]Ln
groupings can cause the ligand-centered or/and metal-centered
luminescence which so far was not investigated for such complexes.
Here, wereportfulldetails of thesynthesisandcharacterizationofthe
trivalent Ce, Nd, Sm, Eu, Gd, Tb, Tm, Yb as well as Sm(II) and Eu(II)
complexes with 3,5-di-tert-butyl-o-benzosemiquinolate and 3,5-di-
2.1. Complexes of trivalent lanthanide
The metal shavings of Dy, Tm, Yb activated by iodine readily
interact with Q at room temperature in a THF medium. The type of
formed products depends on molar ratio of the reagents. It was
found that addition of excess amount of Q to the metal shavings
causes color change of the reaction mixture from red to deep blue.
The products were isolated as blue stable in air solids soluble in the
most of organic solvents. The compounds decompose without
* Corresponding author. Fax: þ7 831 4627497.
E-mail address: kuzyaev@iomc.ras.ru (D.M. Kuzyaev).
0022-328X/$ e see front matter Ó 2011 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2011.10.015

36
D.M. Kuzyaev et al. / Journal of Organometallic Chemistry 698 (2012) 35e41
sublimation at heating over 180 ꢀC in vacuum. The products were
identified by elemental analysis and IR spectroscopy as semi-
quinonato complexes of composition Ln(SQ)3.
saturation for the Tm(1) and Tm(2) atoms which reaches 97.2(2)%
[9]. The semiquinone and catecholate nature of chelate quinone
ligands is confirmed by their CeO distances, which are 1.274(3)e
1.313(3) Å and 1.335(4), 1.391(3) Å respectively for SQ (1.29 Å) and
Cat (1.35 Å) ligands [10].
O
Reactions of Q with excess of metallic Sm, Eu, Tm and Yb in THF
afford catecholates of trivalent lanthanides Ln2(Cat)3(THF)x. One of
the intermediates of the reaction is corresponding semiquinolate as
we can suppose from appearance of blue color of the reaction
solutions. Subsequent heating of the reaction mixtures at 80 ꢀC in
ultrasonic bath led to change of the color from blue to brown (Sm),
black (Eu), green (Tm) and yellow (Yb). The products were isolated
as amorphous air-sensitive solids and were identified by IR spec-
troscopy and elemental analysis. Oxidation degree of metal in the
products was confirmed by their magnetic moments: Sm 2.0 (1.6)
mB, Eu 3.2 (3.5) mB, Tm 7.3 (7.6) mB and Yb 4.1 (4.5) mB which are close
to magnetic moments of respective Ln3þ ions (indicated in brackets
[11]). Some deviations of found meff values from the literature data
imply exchange spin coupling between metal ions in these
complexes.
O
THF
.
Ln
Ln +
3
O
3
O
Ln = Dy, Yb, Tm
Real structure of the products evidently is more complicated
than is represented on the scheme because crystallization of
thulium
compound
from
DME
yielded
the
cluster
Tm3(SQ)4(Cat)2(QH)(DME)2 (1). The one can assume that cat-
echolate ligands are formed due to reduction of semiquinone by
thulium at an initial stage of the reaction. Formation of hydrox-
yphenolate group is caused probably by partial hydrolysis of the
product by traces amount of water remained in the solvent.
Complex 1 is a trinuclear cluster (Fig. 1). The Tm(1), O(7), C(43)
and C(46) atoms lies on twofold axis. Consequently the OH-group
(O(8)eH(8)) is disordered in two symmetrically related positions.
Thulium atoms are linked to each other via bridging m2-oxygen
atoms of the semiquinone (SQ) (O(4), O(4A)), the cateholate (Cat)
(O(6), O(6A)) and the hydroxyphenolate ligands (O(7)). A coordi-
nation number of the thulium atoms is 8. The six-membered Tm(1)
O(4)Tm(2)O(7)Tm(2A)O(4A) metallocycle is not plane. The mean
deviation from planarity is 0.160 Å. The m3-oxygen atoms (O(6),
O(6A)) are disposed over and under center of the Tm(1)O(4)Tm(2)
O(7)Tm(2A)O(4A) fragment forming hexagonalebipyramidal skel-
eton. The Tm(1,2)-O(terminal), Tm(1,2)-m2-O, Tm(1,2)-m3-O and
Tm(2)-O(DME) distances vary in the ranges of 2.177(2)e2.357(2) Å,
2.297(2)e2.390(2) Å, 2.377(2)e2.518(2) Å and 2.435(2)e2.452(2)
Å, respectively. Noticeable overlap between these intervals can be
caused the steric factors, which significantly affects on formation of
distances in ionic TmeO bond lengths. This assumption is
confirmed by very high values of the coordination sphere
O
O
O
O
THF
Ln
Ln
+
3/2
Ln = Sm, Eu, Tm, Yb
The structure of the products has been established with an
example of the samarium complex which turned out four-nuclear
cluster Sm4Cat6(THF)6 (Fig. 2) (2).
Fig. 1. Molecular structure of 1 with ellipsoids of 30% probability. The thermal ellip-
soids correspond to 30% probability. Semiquinone and catecholate ligands are pre-
sented by OCCO fragments for clarity. Selected bond lengths (Ǻ) and angles (ꢀ): Tm(2)e
O(6A) 2.5177(18); Tm(2)eO(1S) 2.452(2); Tm(2)eO(2S) 2.435(2); Tm(1)eO(1)
2.3313(18); Tm(1)eO(2) 2.295(2); Tm(2)eO(3) 2.357(2); Tm(2)eO(4) 2.3101(19);
Tm(1)eO(4) 2.3896(19); Tm(2)eO(5) 2.177(2); Tm(2)eO(7) 2.2973(18); O(1)eC(1)e
C(2) 116.4(2); O(2)eC(2)eC(1) 116.3(3); O(5)eC(29)eC(30) 117.3(3); O(6)eC(30)e
C(29) 115.3(3).
Fig. 2. Molecular structure of complexes 2 (Ln ¼ Sm) and 4 (Ln ¼ Gd). The thermal
ellipsoids correspond to 30% probability. The catecholate ligands and THF molecules
are presented by OCCO fragments and oxygen atoms for clarity.

D.M. Kuzyaev et al. / Journal of Organometallic Chemistry 698 (2012) 35e41
37
Complex 2 lies in the inversion center. The Sm2Cat3(THF)3
fragments in 2 are linked to each other via bridging m3-oxygen
atoms O(6, 6A) and m2-oxygen atoms O(1, 1A). The Sm(1) atom is
coordinated by five oxygen atoms (O(1,2,3,5,6)) of catecholate
ligands and two oxygen ones of THF molecules. Also, there are
shortened distances between the Sm(1) atom and the C(29), C(30)
atoms of the catecholate ligand. The Sm(1)eC(29, 30) distances
(2.847(3) and 2.895(3) Å, respectively) slightly exceed the sum of
ionic and van-der-waals radii of the corresponding atoms: Sm3þ
(CN 9) 1.132 Å [12], C 1.7 Å [13]. As a result of these interactions, the
five membered Sm(2)O(5)C(29)C(30)O(6) metallocycle is not plane.
The dihedral angle between the Sm(2)O(5)O(6) and O(5)C(29)C(30)
O(6) planes is equal 44.0ꢀ that is significantly exceeds the dihedral
angle in the Sm(2)O(3)C(15)C(16)O(4) fragment (7.9ꢀ). In contrast
to the Sm(1) atom, the Sm(2) atom is coordinated by four oxygen
atoms of catecholate ligands (O(3e6)), two oxygen atoms of
symmetry related ones (O(1A) and O(6A)) and one oxygen atom of
THF molecule.
borate]europium(II) [14]) luminescent properties of which were
studied. For preparation of the Eu(II) catecholate we used two
ways: exchange reaction of EuI2 with lithium catecholate Li2(Cat)
and interaction of 3,5-di-tert-butyl-catechol with Eu[N(SiMe3)2]2.
The first reaction proceeds in THF at 75 ꢀC and affords, besides LiI,
the
catecholate
Eu(Cat)(THF)2(DME)4
and
ate-complex
{EuLi4(SQ)2(Cat)2(LiI)2(THF)6}(3) as an air-sensitive pale-yellow
crystals. Value of magnetic moment for the Eu(Cat)(THF)2(DME)4
coincides with that for Eu2þ. Divalent state of europium in the ate-
complex 3 is confirmed by its structure and charge balance.
In a molecule of 3 the two-fold axis passes through the euro-
pium atom Eu(1) (Fig. 3). The fragments of quinone ligands O(1)e
C(1)C(2)O(2), O(3)C(15)C(16)O(4) as well as iodine I(1) and lithium
Li(1e3) atoms with THF molecules are symmetrically independent.
Eight-coordinated europium atom is bonded to the Li(1e3) atoms
via m3-bridging oxygen atoms O(2), O(4) and O(1A) of quinone
ligands. The I(1)eLi(1) distance is 2.752(4) Å and noticably shorter
than the I(1)eLi(2) (2.935(4) Å) and the I(1)eLi(3) (2.954(5) Å)
distances. Also the Li(1)eO(2,4) distances are 1.962(4) and 1.957(5)
Å that is significantly longer than the Li(2,3)eO(2,4) distances
(1.888(4), 1.922(4) Å). Apparently, the Li(1) atom stronger interacts
with iodine atom while the Li(2,3) atoms have more strong inter-
action with oxygen atoms of the quinone ligands.
Analogous catecholates of trivalent Ce, Gd, Nd, Tb were obtained
by the reactions of silylamides Ln[N(SiMe3)2]3 with 3,5-di-tert-
butyl-catechol.
O
HO
The EueO bond lengths vary in the range of 2.373(2)e2.449(2) Å
which are longer than the GdeO distances in Na6[Gd(Cat)3]2
(2.347e2.372 Å) [3] and comparable with the SmeO distances in
Sm(TpMe)2(SQ) (2.386e2.428 Å) [7]. It should be noted, that the
CeO distances (1.345(3)e1.377(3) Å) correspond to a dianionic
THF
Ln
Ln[N(SiMe3)2]3
+
- 3HN(SiMe3)2
O
3/2
HO
Ln = Ce, Gd, Nd, Tb
The products, isolated in high yields as air-sensitive colored
solids, were identified by IR spectroscopy and elemental analysis.
X-ray structure determination revealed that gadolinium cat-
echolate (4) is isostructural to the samarium complex 2 (Fig. 2). The
comparison of distances in 2 and 4 shows that GdeO bond lengths
in 4 are systematically shorter as compared with the SmeO
distances in 2 (Table 1). Other structural regularities in complexes 2
and 4 have a similar character.
2.2. Complexes of Sm(II) and Eu(II)
Quinone complexes of divalent lanthanides are of special
interest because: (i) no one of such compounds were synthesized
up to now and (ii) there is only one compound of divalent lantha-
nide with anionic organic ligands (bis[tris(dimethylpyrazolyl)
Table 1
Bond lengths and angles in 2 and 4.
ꢀ
Bond
d, Å
Angle
u
,
2
4
2
4
Ln(1)eO(1)
Ln(1)eO(2)
Ln(1)eO(4)
Ln(1)eO(5)
Ln(1)eO(6)
Ln(2)eO(3)
Ln(2)eO(4)
Ln(2)eO(5)
Ln(2)eO(6)
2.343(2) 2.308(2) Ln(1)eO(1)eLn(2A) 111.50(9) 112.30(8)
2.241(2) 2.248(2) Ln(1)eO(4)eLn(2)
2.292(2) 2.262(2) Ln(1)eO(5)eLn(2)
2.458(2) 2.455(2) Ln(1)eO(6)eLn(2)
99.18(8)
92.33(8)
93.15(7)
97.99(7)
91.00(6)
91.84(6)
2.537(2) 2.521(2) Ln(1)eO(6)eLn(2A) 104.22(8) 104.31(7)
2.188(2) 2.186(2) Ln(2)eO(6)eLn(2A) 112.01(8) 115.11(8)
2.416(2) 2.391(2) O(1)eLn(1)eO(4)
2.513(2) 2.468(2) O(1)eLn(1)eO(5)
2.399(2) 2.366(2) O(4)eLn(1)eO(5)
101.77(8) 103.42(7)
126.55(7) 124.61(6)
75.45(8)
75.96(7)
77.45(7)
76.30(7)
Ln(2)eO(6A) 2.411(2) 2.391(2) O(4)eLn(1)eO(6)
Ln(2)eO(1A) 2.381(2) 2.363(2) O(4)eLn(2)eO(1A) 134.69(8) 131.99(7)
O(1)eC(1)
O(2)eC(2)
C(1)eC(2)
O(3)eC(15)
O(4)eC(16)
C(15)eC(16) 1.410(5) 1.417(4)
O(5)eC(29)
O(6)eC(30)
1.363(4) 1.374(3) O(5)eLn(2)eO(1A) 151.72(8) 151.02(6)
1.346(4) 1.346(4) O(4)eLn(2)eO(5)
1.400(5) 1.419(4) O(4)eLn(2)eO(6)
1.348(4) 1.352(3) O(6)eLn(2)eO(6A)
1.367(4) 1.363(3)
72.34(7)
76.39(7)
67.99(8)
74.90(7)
77.00(6)
64.89(8)
Fig. 3. Molecular structure of complex 3. The thermal ellipsoids correspond to 30%
probability. The catecholate ligands and THF molecules are presented by OCCO frag-
ments and oxygen atoms for clarity. Selected bond lengths (Ǻ) and angles (ꢀ): I(1)e
Li(1) 2.752(4); I(1)eLi(2) 2.935(4); I(1)eLi(3) 2.954(5); Eu(1)eO(4) 2.3734(15); Eu(1)e
O(2) 2.3774(15); Eu(1)eO(1) 2.4356(15); Eu(1)eO(3) 2.4486(19); C(15)eC(16)
1.427(3); O(3)eC(15) 1.360(3); O(4)eC(16) 1.345(3); C(1)eC(2) 1.416(3); O(1)eC(1)
1.377(3); O(2)eC(2) 1.359(2); Li(2)eLi(1)eLi(3) 61.04(15); Li(2)eLi(3)eLi(1) 57.27(14);
Li(1)eLi(2)eLi(3) 61.69(15); O(1)eC(1)eC(2) 116.26(18); O(2)eC(2)eC(1) 117.98(18).
1.355(4) 1.371(3)
1.377(4) 1.387(3)
C(29)eC(30) 1.414(4) 1.412(4)

38
D.M. Kuzyaev et al. / Journal of Organometallic Chemistry 698 (2012) 35e41
800.0
600
400
200
0.0
form of all quinone ligands [10]. However, charge balance shows,
that complex 3 contains two anion-radical semiquinone groups,
two dianion catecholate ligands, Eu2þ cation and four Liþ cations,
besides two neutral LiI molecules. Apparently CeO distances in this
case are not well distinguished due to charge exchange interaction
between SQ and Cat ligands similar to those observed in the
phenanthrene-o-iminoquinone complexes of Nd and Dy [15].
In order to avoid the ate-complex formation catecholates of
divalent Eu and Smwere synthesized by treatment of corresponding
silylamide complexes with 3,5-di-tert-butyl-catechol. Products
were isolated in high yield as amorphous air-sensitive solids.
300.0
350
400
450
500
nm
550
600
650
700.0
O
HO
THF
Ln
Ln[N(SiMe3)2]2
Ln = Sm, Eu
+
Fig. 5. Luminescence spectrum of Tb2(Cat)3 in THF solution (lex 312 nm).
- 2HN(SiMe3)2
O
HO
300e350 nm with maximum at 310 nm, which coincides with the
absorption bands of the ligands. It testifies about effective excita-
tion energy transfer from ligands to Tb3þ cation and, consequently,
about conformity of energy of frontal orbitals of the ligands [16] to
energy of resonance 5D4 level of Tb3þ cation.
3. UV/VIS spectra and photoluminescent properties of
prepared lanthanide complexes
Absorption spectra of semiquinonato complexes Ln(SQ)3 (Ln ¼
Dy, Yb, Tm) in THF solution have two bands in near UV region with
maxima at 305 and 380 nm. The band at 380 nm reveals vibrational
structure with maxima at 348, 363 and 378 nm (Fig. 4) which can be
assigned to intraligand electron transfer under UV-irradiation. In
a visible region one broad band of low intensity at 750 nm is
observed which stipulates blue color of the complexes. Appearance
of this band can be attributed to a ligand-metal charge transfer.
Spectraof trivalentCe, Nd,Gd, Tb,Tm, YbaswellasSm(II)andEu(II)
catecholates are similar to those of the semiquinonato complexes but
thebandat305 nmisobservedasashoulderwhilethebandat380 nm
has noticeable vibrational structure only for Tm2(Cat)3. Absorption
peak at 378 nm is the most intensive in this region. It should be noted
that intensities of bandsat a region of 380 nm for these compounds are
varying in wide range depending on the metals. Differences are
observed as well in long-wave region of spectra: a band at 750 nm in
the cases of Eu, Tm, and Sm derivatives is noticeably stronger than that
in the spectra of Gd, Tb and Yb compounds.
4. Experimental
4.1. Physical measurements and materials
All experiments were performed in evacuated tubes using stan-
dard Schlenk techniques, thus excluding traces of air and water.
Solvents were purified by distillation from sodium/benzophenone
ketyl (THF and DME) and sodium (hexane). THF for electron spec-
troscopy was treated with NdI2 before use [17]. 3,5-Di-tert-butyl-o-
benzoquinone, 3,5-di-tert-butyl-catechol, Dy, Yb, Tm, Sm, Eu were
purchased from Aldrich company. Silylamide complexes of lantha-
nides Ln[N(SiMe3)2]n (n ¼ 2, 3) were prepared according to the
published procedures [18e20]. IR spectra were recorded on a Spe-
cord M-75 instrument in region of 4000e450 cmꢁ1. Samples were
prepared under argon atmosphere as Nujol mulls. Magnetic
susceptibility measurements were carried out according to known
procedures [21]. Absorption spectra were recorded on a UV/VIS
instrument “PerkineElmer Lambda-25” from 200 to 500 nm. Emis-
sion spectra were registered from 300 to 700 nm on a fluorescent
spectrometer “PerkineElmer LS-55”. Registration of absorption and
emission spectrawere performed in 1 cm fluorescent quartz cuvette.
Among the prepared benzoquinone complexes only terbium
catecholate Tb2(Cat)3 has shown photoluminescence (Fig. 5).
Emission spectrum of it in a THF solution has a typical for Tb3þ
cation set of bands with maxima at 490, 540, 585 and 625 nm,
which are stipulated by f-f transitions 5D4 / 7Fn (n 0e6). Excitation
spectrum shows intensive energy absorption at region of
4.2. Synthesis details
4.2.1. Reaction of Tm with Q (1:3)
RedsolutionofquinoneQ(0.394 g,1.79 mmol)in10 mlofTHFwas
added to thulium shavings (0.127 g, 0.75 mmol) activated by iodine
(3 mg, 0.01 mmol). During 3 h colorof the reaction mixture gradually
changed to dark blue. The resulting solution was filtered and solvent
was removed by condensation in vacuo. Crystallization of the residue
fromDME gave blue crystals of1 (0.107 g,18%) which were used for X-
ray analysis. Found (%):C, 56.68, H, 7.60. C106H161O18Tm3. Calculated
(%): C, 56.80, H, 7.58. DME was evaporated from mother liquor in
vacuo and residue was washed by cold hexane. Blue amorphous solid
of Tm(SQ)3(DME)3 (0.381 g, 58%) was obtained. Found (%): C, 58.87, H,
8.44.C54H90O12Tm. Calculated(%):C,58.95,H,8.18.IR(Nujol), n :
/cmꢁ1
2385 w, 1663 s, 1623 m, 1582 m, 1514 s, 1487 s, 1359 m, 1273 w,
1245 m,1204 w,1095 w,1070 w,1026 m, 984 m, 953 w, 906 w, 891 m,
870 w, 858 w, 828 w, 802 w, 791 w, 745 m, 722 m, 673 w, 656 m,
598 w, 572 m, 537 w, 514 w, 463 w, 433 w.
Fig. 4. Absorption spectra of Tm(SQ)3(1) and Tm2(Cat)3 (2) in THF solution.

D.M. Kuzyaev et al. / Journal of Organometallic Chemistry 698 (2012) 35e41
39
4.2.2. Reaction of Dy with Q (1:3)
overnight. Formedpale-yellowcrystalsof3(0.196 g,8%)wereisolated
by decantation and used for X-ray analysis. IR (Nujol),
/cmꢁ1: 3428 s,
Red solution of Q (0.648 g, 2.94 mmol) in 10 ml of THF was added
to dysprosium shavings (0.178 g, 1.10 mmol) activated by iodine
(3 mg, 0.01 mmol). Within 3 h color of the reaction mixture
changed to dark blue. The resulting solution was filtered, solvent
was removed by condensation in vacuo and solid residue was
washed with cold hexane to give blue powder of Dy(SQ)3(THF)
(0.813 g, 93%). Found (%): C, 61.17, H, 7.34. C46H68O7Dy. Calculated
n
1598 m, 1549 w, 1520 w, 1417 w, 1317 m, 1234 m, 1202 w, 1174 w,
1144 w, 1113 w, 1075 w, 1032 m, 983 m, 918 w, 871 m, 824 w, 806 w,
731 w, 660 w, 560 m. After removal of solvent from mother liquor
resulting solid was dissolved in 10 ml DME. Cooling and concentra-
tionofthesolutionledtoformationcolorlesscrystalsoflithiumiodide
which was separated by decantation. DME was evaporated from the
mother liquor and residue was washed by cold hexane to give yellow
solid of Eu(Cat)(THF)2(DME)4 (0.553 g, 46%). Found (%): C, 52.28, H,
(%): C, 61.69, H, 7.59. IR (Nujol), n
/cmꢁ1: 2385 w, 2281 w, 1584 s,
1515 s, 1489 s, 1359 s, 1331 w, 1294 w, 1247 m, 1204 m, 1096 s,
1072 w, 1028 s, 985 s, 906 m, 860 m, 828 m, 803 m, 791 m, 744 m,
723 w, 671 m, 655 m, 598 m, 573 s, 536 m, 506 m, 459 m, 440 m.
8.59. C38H76O12Eu. Calculated (%): C, 52.03, H, 8.67. IR (Nujol), n :
/cmꢁ1
2388 w, 2290 w, 2062 w, 1948 w, 1707 w, 1585 m, 1546 s, 1416 w,
1359 w, 1315 s, 1242 s, 1199 w, 1178 w, 1118 w, 1081 w, 1023 m, 975 s,
913 w, 853 s, 829 m, 808 s, 776 m, 746 s, 723 w, 662 s, 591 m, 524 m
4.2.3. Reaction of Yb with Q (1:3)
Under conditions of previous experiment 0.531 g (97%) of
Yb(SQ)3(THF) was obtained from quinone Q (0.40 g, 1.82 mmol) and
Yb shavings (0.115 g, 0.66 mmol). Found (%): C, 60.68, H, 7.35.
C46H68O7Yb. Calculated (%): C, 60.97, H, 7.50. IR spectrum of the
product is analogous to that for complex Dy(SQ)3(THF).
4.2.9. Reaction of Gd[N(SiMe3)2]3 with 3,5-di-tert-butyl-catechol
Solution of Gd[N(SiMe3)]3 (0.389 g, 0.61 mmol) in 10 ml THF was
added to solution of 3,5-di-tert-butyl-catechol (0.203 g, 0.91 mmol)
and reaction mixture left stirred overnight. The resulting solutionwas
filtered and solvent was removed by condensation in vacuo. Washing
of residue by cold hexane yielded 0.29 g (91%) pale-green solid of
Gd2(Cat)3(THF). Found (%): C, 53.00, H, 7.10. C46H68O7Gd2. Calculated
4.2.4. Reaction of Sm with Q (1:1)
A mixture of Sm shavings (0.177 g,1.18 mmol) activated by iodine
(3 mg, 0.01 mmol) and quinone Q (0.220 g, 1.00 mmol) in 15 ml of
THF was placed to ultrasonic bath at 75 ꢀC for 6 h. The resulting
solution was filtered and solvent was removed by condensation in
vacuo. Washing of residue by cold hexane yielded 0.308 g (90%) of
brown amorphous solid of Sm2(Cat)3(THF). meff ¼ 2.0 mB. Found (%):
C, 53.10, H, 7.16. C46H68O7Sm2. Calculated (%): C, 53.45, H, 6.58. IR
(%): C, 52.75, H, 6.50. IR (Nujol), n
/cmꢁ1: 1583 m, 1547 w, 1522 w,
1419 m, 1317 m, 1248 s, 1202 w, 1177 w, 1148 w, 1113 w, 1075 w,
1028 m, 977 s, 931 m, 846 m, 810 w, 745 m, 660 m, 619 w, 594 w,
548 w, 525 w. The product was recrystallized from hexane to yield
colorless crystals of 4 which were used for X-ray diffraction study.
(Nujol),
n
/cmꢁ1: 2381 w, 2285 w, 1723 w, 1581 s, 1527 s, 1417 m,
4.2.10. Reaction of Tb[N(SiMe3)2]3 with 3,5-di-tert-butyl-catechol
Under conditions of previous experiment from 0.290 g
(0.45 mmol) of Tb[N(SiMe3)]3 and 0.151 g (0.68 mmol) of 3,5-di-tert-
butyl-catechol gray solid of Tb2(Cat)3(THF)2 (0.224 g, 88%) was ob-
tained. Found (%): C, 53.00, H, 6.47. C50H76O8Tb2. Calculated (%): C,
53.48, H, 6.77. IR spectrum of the product is analogous to that for
complex Gd2(Cat)3(THF).
1359 m, 1315 s, 1259 s, 1234 w, 1203 m, 1174 w, 1114 w, 1098 w,
1074 w, 1028 s, 981 s, 914 m, 875 m, 859 m, 829 m, 809 m, 791 w,
772 w, 744 s, 665 s, 654 w, 597 m, 581 m, 547 w, 528 m, 499 w,
482 w, 439 m. The product was recrystallized from THF to yield
colorless crystals of 2 which were used for X-ray diffraction study.
4.2.5. Reaction of Eu with Q (1:1)
Underconditions of previousexperiment from 0.421 g (1.91 mmol)
of Q and 0.309 g (2.03 mmol) of Eu shavings 0.773 g (78%) of
Eu2(Cat)3(THF) as black solid was obtained. meff ¼ 3.2 mB. Found (%): C,
52.83, H, 6.54. C46H68O7Eu2. Calculated (%): C, 53.28, H, 6.56. IR spec-
trum of the product is analogous to that for complex Sm2(Cat)3(THF).
4.2.11. Reaction of Ce[N(SiMe3)2]3 with 3,5-di-tert-butyl-catechol
Under conditions of previous experiment from 0.257 g
(0.41 mmol) of Ce[N(SiMe3)2]3 and 0.138 g (0.62 mmol) of 3,5-di-
tert-butyl-catechol dark-violet solid of Ce2(Cat)3(THF)3 (0.187 g,
79%) was obtained. Found (%): C, 56.13, H, 7.51. C54H84O9Ce2.
Calculated (%): C, 56.00, H, 7.30. IR spectrum of the product is
analogous to that for complex Gd2(Cat)3(THF).
4.2.6. Reaction of Yb with Q (1:1)
A total of 0.407 g (87%) of yellow Yb2(Cat)3(THF) was obtained
from 0.288 g (1.31 mmol) of Q and 0.243 g (1.40 mmol) of Yb
4.2.12. Reaction of Nd[N(SiMe3)2]3 with 3,5-di-tert-butyl-catechol
Under conditions of previous experiment from 0.250 g
(0.40 mmol) of Nd[N(SiMe3)2]3 and 0.135 g (0.61 mmol) of 3,5-di-
tert-butyl-catechol pale-blue solid of Nd2(Cat)3(THF) (0.233 g, 96%)
was obtained. Found (%): C, 53.71, H, 7.05. C46H68O7Nd2. Calculated
(%): C, 54.08, H, 6.66. IR spectrum of the product is analogous to that
for complex Gd2(Cat)3(THF).
shavings under conditions of previous experiment. meff ¼ 4.1 mB
.
Found (%): C, 50.81, H, 6.30. C46H68O7Yb2. Calculated (%): C, 51.20, H,
6.30. IR spectrum of the product is analogous to that of
Sm2(Cat)3(THF).
4.2.7. Reaction of Tm with Q (1:1)
Underconditions of previous experimentfrom0.260 g(1.18 mmol)
of Q and 0.219 g (1.30 mmol) of Tm shavings 0.320 g (52%) of green
solid of Tm2(Cat)3(THF)8 was obtained. meff ¼ 7.3 mB. Found (%): C,
55.90, H, 7.53. C74H124O14Tm2. Calculated (%): C, 56.39, H, 7.87. IR
spectrum of the product is analogous to that of Sm2(Cat)3(THF).
4.2.13. Reaction of Sm[N(SiMe3)2]2(THF)4 with 3,5-di-tert-butyl-
catechol
Under conditions of previous experiment from 0.250 g
(0.31 mmol) of Sm[N(SiMe3)2]2(THF)4 and 0.073 g (0.33 mmol) of
3,5-di-tert-butyl-catechol green solid of Sm(Cat)(THF) (0.192 g,
98%) was obtained. Found (%): C, 48.45, H, 6.55. C18H28O3Sm.
Calculated (%): C, 48.82, H, 6.32. IR spectrum of the product is
analogous to that for complex Gd2(Cat)3(THF).
4.2.8. Reaction of EuI2 with Li2(Cat)
To a suspension of lithium catecholate in THF (prepared from
0.305 g (1.384 mmol) of 3,5-di-tert-butyl-catechol and excess of Li)
a solution of EuI2(THF)2 (0.758 g, 1.378 mmol) in 15 ml THF was
added. Reaction mixture was stirred at 75 ꢀC for 5 h. Gradual disso-
lution of precipitate of lithium catecholate was observed. After
filtration,THFwasremovedundervacuumandtheresultingsolidwas
extracted by hexane (3ꢂ10 ml). The extract was concentrated and left
4.2.14. Reaction of Eu[N(SiMe3)2]2(DME)2 with 3,5-di-tert-butyl-
catechol
Under conditions of previous experiment from 0.345 g
(0.53 mmol) of Eu[N(SiMe3)2]2(DME)2 and 0.117 g (0.53 mmol) of

40
D.M. Kuzyaev et al. / Journal of Organometallic Chemistry 698 (2012) 35e41
Table 2
The details of crystallographic, collection and refinement data for 1e4.
Complex
1
2
3
4
Empirical formula
Formula weight
Temperature [K]
Wavelength [Å]
Crystal system
Space group
C114H181O22Tm3
2410.38
100(2)
0.71073
Monoclinic
C2/c
C124H200O22Sm4
2644.24
100(2)
0.71073
Monoclinic
P2(1)/c
C83H135EuI2Li6O14
1804.31
100(2)
0.71073
Tetragonal
I4(1)
C114H182O18Gd4
2469.60
100(2)
0.71073
Monoclinic
P2(1)/n
Unit cell
dimensions
a [Å]
14.2086(5)
33.6469(13)
25.6266(10)
90
90.4740(10)
90
15.0017(4)
14.7697(4)
28.6779(8)
90
101.0580(10)
90
25.3572(6)
25.3572(6)
14.6810(4)
90
90
90
14.0644(6)
16.3956(7)
24.4673(11)
90
91.1280(10)
90
b [Å]
c [Å]
a
b
g
[ꢀ]
[ꢀ]
[ꢀ]
Volume [Å3]
Z
12 251.0(8)
4
6236.2(3)
2
9439.7(4)
4
5640.9(4)
2
Density
1.307
1.408
1.270
1.454
(calculated) [g cmꢁ3
Absorption
]
2.215
1.920
1.372
2.383
coefficient [mmꢁ1
]
Crystal size [mm3]
0.40 ꢂ 0.15 ꢂ 0.09
2.22e26.00
0.25ꢂ 0.07 ꢂ 0.06
1.95e26.00
0.20ꢂ 0.18ꢂ 0.17
2.27e26.50
0.38ꢂ 0.27ꢂ 0.10
1.68e26.00
q
range for data
collection [ꢀ]
Limiting indices
ꢁ17 ꢃ h ꢃ 17,
ꢁ41 ꢃ k ꢃ 41,
ꢁ31 ꢃ l ꢃ 31
51 949/11953
ꢁ18 ꢃ h ꢃ 18,
ꢁ18 ꢃ k ꢃ 18,
ꢁ35 ꢃ l ꢃ 35
52 554/12173
ꢁ31 ꢃ h ꢃ 23,
ꢁ31 ꢃ k ꢃ 28,
ꢁ16 ꢃ l ꢃ 18
29 772/9408
ꢁ17 ꢃ h ꢃ 17,
ꢁ20 ꢃ k ꢃ 20,
ꢁ30 ꢃ l ꢃ 30
47 788/11057
Reflections
collected/unique
R(int)
0.0399
0.0374
0.0224
0.0545
Completeness (to
Absorption
correction
q
)
99.1% (26.00)
Semi-empirical from
equivalents
99.4% (26.00)
Semi-empirical from
equivalents
99.4% (26.50)
Semi-empirical
from equivalents
0.8003 and 0.7710
99.7% (26.00)
Semi-empirical
from equivalents
0.7471 and 0.4970
Max. and min.
transmission
Refinement
method
Data/restraints
/parameters
Final R indices
[I > 2sigma(I)]
0.7750 and 0.4007
0.8935 and 0.6454
Full-matrix
Full-matrix
Full-matrix
Full-matrix
least-squares on F2
11 953/141/621
least-squares on F2
12 173/116/726
least-squares on F2
9408/112/521
least-squares on F2
11 057/30/635
R1¼ 0.0396,
wR2 ¼ 0.1003
R1 ¼ 0.0618,
wR2 ¼ 0.1093
1.033
R1 ¼ 0.0429,
wR2 ¼ 0.1098
R1 ¼ 0.0582,
wR2 ¼ 0.1169
1.043
R1 ¼ 0.0281,
wR2 ¼ 0.0711
R1 ¼ 0.0311,
wR2 ¼ 0.0725
1.015
R1 ¼ 0.0381,
wR2 ¼ 0.0957
R1 ¼ 0.0496,
wR2 ¼ 0.1019
1.063
R indices (all data)
Goodness-of-fit on F2
Absolute structure
parameter
e
e
ꢁ0.019(8)
e
Largest diff. peak
2.629 and ꢁ1.662
1.685 and ꢁ1.201
1.052 and ꢁ0.585
2.687 and ꢁ0.849
and hole [e/Å3]
3,5-di-tert-butyl-catechol yellow solid of Eu(Cat)(THF) (0.187 g,
79%) was obtained. Found (%): C, 48.32, H, 6.81. C18H28O3Eu.
Calculated (%): C, 48.64, H, 6.30. IR spectrum of the product is
analogous to that for complex Gd2(Cat)3(THF).
positions, one of them is disordered in two positions; in 2 four THF
molecules in common positions; in 3 half of hexane molecule in
special position and in 4 one hexane molecule disordered in two
special positions. Details of crystallographic, collection and refine-
ment data for 1e4 are given in Table 2.
CCDC- 825653 (1), 825 654 (2), 825 655 (3) and 825 656 (4)
contain the supplementary crystallographic data for this paper.
These data can be obtained free of charge at www.ccdc.cam.ac.uk/
conts/retrieving.html [or from the Cambridge Crystallographic Data
Center, 12, Union Road, Cambridge CB2 1EZ, UK; fax:
(internat.) þ44-1223/336-033; Email: deposit@ccdc.cam.ac.uk.
4.3. Crystallographic data for 1e4
Intensity data for 1e4 were collected on a Smart Apex diffrac-
tometer with graphite monochromated Mo-Ka radiation
(l 0.71073 Å) in the uef scan mode (u
0.3ꢀ, 10 s on each frame). The
intensity data were integrated by SAINT program [22]. SADABS [23]
was used to perform area-detector scaling and absorption correc-
tions. The structures were solved by direct (1, 2 and 4) and Pat-
terson (3) methods and were refined on F2 using all reflections with
SHELXTL package [24]. All non-hydrogen atoms were refined
anisotropically. Hydrogen atoms were placed in calculated posi-
tions and refined in the “riding-model” (Uiso(H) 1.5Ueq(C) in CH3-
groups and Uiso(H) 1.2Ueq(C) in other ligands), except for one
hydrogen atom of OH group in 1, obtained from differential Fourier-
synthesis and refined isotropically. There are solvent molecules in
1e4 per one Ln complex: in 1 two DME molecules in special
5. Conclusions
In this paper, semiquinonato complexes of lanthanides Ln(SQ)3
(Ln ¼ Dy, Tm, Yb) were obtained by treatment of metal with excess of
quinone Q. Catecholates of trivalent (Sm, Eu, Tm, Yb, Ce, Gd, Nd, Tb)
and divalent (Eu, Sm) lanthanides were prepared by three ways: (i)
interaction of equimolar amounts lanthanide and quinone Q, (ii)
exchange reaction of EuI2 with lithium catecholate; (ii) treatment of
silylamides Ln[N(SiMe3)2]n (n ¼ 2, 3) with 3,5-di-tert-butyl-catechol.

D.M. Kuzyaev et al. / Journal of Organometallic Chemistry 698 (2012) 35e41
41
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Photoluminescense properties of the prepared benzoquinone
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625 nm, is typical for metal-centered emission of Tb3þ complexes.
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Acknowledgements
The work was supported by the Russian Foundation for Basic
Research (Grants No. 10-03-00190, 11-03-97037).
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