Lanthanide pentafluorophenolates. Synthesis, structure and luminescent properties

Article abstract of DOI:10.1016/j.jorganchem.2013.03.052

The pentafluorophenolates of lanthanides Ln(OC₆F ₅)₃ (Ln = Nd (1), Tb (2), Er (3)) were prepared by the reactions of pentafluorophenol with appropriate silylamides Ln[N(SiMe ₃)₂]₃ in benzene or toluene solution. The same reactions in ether or methanol medium afforded the solvated complexes Ln(OC ₆F₅)₃(Et₂O)₃ (Ln = Nd (4), Eu (5), Tb (6), Er (7), Gd (8)) or Nd(OC₆F₅) ₃(MeOH)₃ (9), respectively. The phenanthroline complexes Ln(C₆F₅O)₃(phen) (Ln = Pr (10), Nd (11), Er (12)), Ln(OC₆F₅)₃(phen)₂ (Ln = Sm (13), Tb (14), Ho (15), Ln(OC₆F₅)₃(phen) ₂(Et₂O) (Ln = Eu (16), Yb (17)), and Ln(OC ₆F₅)₃(phen)(Et₂O)₃ (Ln = Eu (18), Nd (19), Ce (20), Dy (21)), Ln(OC₆F₅) ₃(phen)₂(H₂O) (Ln = Sm (22), Ho (23)), and Gd(OC₆F₅)₃(phen)₂(MeOH) (24) were obtained when the reactions were carried out in the presence of 1,10-phenanthroline. The complexes with pyridine Tb(OC₆F ₅)₃(py)₅ (25) and 2,2′-bipyridyl Ln(OC₆F₅)₃(bpy)₂ (Ln = Tb (26), Yb (27)) were synthesized similarly. Compounds 7, 22, 23, and 24 were characterized by X-ray analysis. The complexes Ln(OC₆F₅)₃ decompose above 150 C in vacuum to give lanthanide fluorides and octofluorodibenzo-p-dioxine. Phenanthroline derivatives are stable up to 310 C. Luminescence spectra of all the obtained complexes in visible region contain a broad band of ligand-centered emission peaked at 405-415 nm. Spectra of samarium 13, europium 5, 16, 18 and terbium 14, 25, 26 derivatives display also the characteristic narrow bands of Sm³⁺, Eu³⁺ and Tb ³⁺ ions.

Full text of DOI:10.1016/j.jorganchem.2013.03.052

Journal of Organometallic Chemistry xxx (2013) 1e7
Contents lists available at SciVerse ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Lanthanide pentafluorophenolates. Synthesis, structure and luminescent
properties
*
Alexander A. Maleev , Anatoly A. Fagin, Vasily A. Ilichev, Mikhail A. Lopatin, Alexey N. Konev,
Maksim A. Samsonov, Georgy K. Fukin, Mikhail N. Bochkarev
G.A. Razuvaev Institute of Organometallic Chemistry of Russian Academy of Sciences, Tropinina 49, 603950 Nizhny Novgorod, Russia
a r t i c l e i n f o
a b s t r a c t
Article history:
The pentafluorophenolates of lanthanides Ln(OC6F5)3 (Ln ¼ Nd (1), Tb (2), Er (3)) were prepared by the
reactions of pentafluorophenol with appropriate silylamides Ln[N(SiMe3)2]3 in benzene or toluene so-
Received 21 February 2013
Received in revised form
29 March 2013
lution. The same reactions in ether or methanol medium afforded the solvated complexes Ln(OC6
-
F5)3(Et2O)3 (Ln ¼ Nd (4), Eu (5), Tb (6), Er (7), Gd (8)) or Nd(OC6F5)3(MeOH)3 (9), respectively. The
phenanthroline complexes Ln(C6F5O)3(phen) (Ln ¼ Pr (10), Nd (11), Er (12)), Ln(OC6F5)3(phen)2 (Ln ¼ Sm
(13), Tb (14), Ho (15), Ln(OC6F5)3(phen)2(Et2O) (Ln ¼ Eu (16), Yb (17)), and Ln(OC6F5)3(phen)(Et2O)3
(Ln ¼ Eu (18), Nd (19), Ce (20), Dy (21)), Ln(OC6F5)3(phen)2(H2O) (Ln ¼ Sm (22), Ho (23)), and
Gd(OC6F5)3(phen)2(MeOH) (24) were obtained when the reactions were carried out in the presence of
1,10-phenanthroline. The complexes with pyridine Tb(OC6F5)3(py)5 (25) and 2,20-bipyridyl
Ln(OC6F5)3(bpy)2 (Ln ¼ Tb (26), Yb (27)) were synthesized similarly. Compounds 7, 22, 23, and 24 were
characterized by X-ray analysis. The complexes Ln(OC6F5)3 decompose above 150 ꢀC in vacuum to give
lanthanide fluorides and octofluorodibenzo-p-dioxine. Phenanthroline derivatives are stable up to
310 ꢀC. Luminescence spectra of all the obtained complexes in visible region contain a broad band of
ligand-centered emission peaked at 405e415 nm. Spectra of samarium 13, europium 5, 16, 18 and
terbium 14, 25, 26 derivatives display also the characteristic narrow bands of Sm3þ, Eu3þ and Tb3þ ions.
Ó 2013 Elsevier B.V. All rights reserved.
Accepted 29 March 2013
Dedicated to Professor V.I. Bregadze on
occasion of his 75th birthday.
Keywords:
Lanthanide
Pentafluorophenol
Phenanthroline
Photoluminescence
Electroluminescence
1. Introduction
(NIR) luminescence of the compounds of these metals with non-
fluorinated ligands. It should be noted that the NIR emitting
It is known that perfluorinated ligands increase the thermal and
chemical stability, solubility and volatility of organometallic com-
pounds including polynuclear derivatives [1]. The same effect the
C6F5 groups have on the properties of lanthanide complexes,
although thermal stability of the compounds in this case is reduced
compared to non-fluorinated analogs due to intramolecular inter-
action of o-F atoms with neighboring metal atom resulting in LnF3
formation [2]. Perfluorinated phenolate and thiophenolate ligands
in the lanthanide complexes attract the particular attention
because the absence in their molecules of the CeH bonds, which
are effective quenchers of luminescence, facilitates enhance of the
emission of these complexes. Among this class of compounds it is
known to date the perfluorinated phenolates of Eu [3], Nd, Er, Tm
[4] and thiophenolates of Ce, Sm, Eu, Ho, Yb [5], Nd [6], Er [7], and
Tm [8]. In all these cases the complexes contain coordinated mol-
ecules of DME, pyridine or THF. The compounds of Nd, Er, and Tm
excited by UV light displayed the metal-centered emission, in-
tensity of which really significantly exceeded the near-infrared
luminophores have attracted increasing intention, due to their
potential application in optical fiber communication, fluo-
roimmunoassay, in laser systems, security systems and other fields
[9]. It was of interest to prepare thermally stable and non-
hygroscopic lanthanide pentafluorophenolates which would be
suitable for OLEDs design. In this paper we report on the synthesis,
structure and photoluminescence characteristics of a set of new
stable C6F5O derivatives of Nd, Sm, Eu, Gd, Er, Tb, Tm, and Yb
potentially applicable for preparation of emissive layers.
2. Experimental section
2.1. General methods
The syntheses and manipulations of the compounds described
below were conducted with exclusion of air and water using
Schlenk techniques. Reagent-grade chemicals were used in all ex-
periments, and solvents were purified using standard procedures
and collected in a reaction vessel by condensation in vacuum.
Pentafluorophenol, 2,20-bipyridyl, 1,10-phenanthroline were pur-
chased from Aldrich and used without additional purification.
* Corresponding author.
E-mail address: maleev@iomc.ras.ru (A.A. Maleev).
0022-328X/$ e see front matter Ó 2013 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.jorganchem.2013.03.052
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2
A.A. Maleev et al. / Journal of Organometallic Chemistry xxx (2013) 1e7
Silylamides Ln[N(SiMe3)2]3 were prepared according to the pub-
lished procedures [10]. Content of metal was determined by com-
plexometric titration after removal of the split organic ligands.
hexaneand dried invacuum to give 0.334 g (94%) of9; m.p. in a sealed
capillary >120 ꢀC (dec.). Anal. Calcd for C21NdH12F15O6 (789.53): Nd,
18.27. Found: Nd, 17.87%. IR (Nujol, n
/smꢁ1): 3684m, 3648m, 3607m,
3328m, 1686w, 1650m, 1617m, 1592m, 1573m, 1503s, 1421m, 1246w,
1172m, 1104w, 1019s, 988s, 862m, 844m, 731m, 629w.
2.2. Physical measurements
IR spectra were recorded on a Specord M-75 spectrometer from
4000 to 450 cme1. The samples were prepared as Nujol mulls and as
films between KBr plates. UVevis spectra were recorded with a UV-
VIS-NIR UV-3600 Shimadzu spectrometer in a region from 300 to
1500 nm. The photoluminescence spectra were recorded from 400 to
800 nm on a spectrometer Fluorescence LS-55 (spectral resolution
1 nm) with excitation at 300e400 nm. Differential scanning calorim-
etry (DSC) was carried out on a DSC 204 F1 “Phoenix”(“Netzsch”)using
a dry nitrogen atmosphere (flow rate of 20 cm3 minꢁ1, heating rate of
5ꢀ minꢁ1 in alumina crucibles). Thermogravimetric analysis (TGA) was
carried out on a PYRIS-6-TGA (PerkineElmer) in nitrogen flow (heating
from 50 to 600 ꢀC, flow rate 20 cm3 minꢁ1, heating rate 10ꢀ minꢁ1).
2.6. Preparation of Pr(OC6F5)3(phen) (10)
To a solution of Pr[N(SiMe3)2]3 (0.152 g, 0.244 mmol) in 5 ml
toluene a solution of C6F5OH (0.135 g, 0.733 mmol) and 1,10-
phenanthroline (0.044 g, 0.244 mmol) in 5 ml toluene was added.
The pale green microcrystalline precipitate was deposited from a
solution in 15 h. The product was washed with hexane and dried in
vacuum to give 0.277 g (97%) of 10; m.p. in a sealed capillary
>300 ꢀC (dec.). Anal. Calcd for C30PrH8F15N2O3 (870.28): Pr, 16.19.
Found: Pr, 16.34%. IR (Nujol, n
/smꢁ1): 1650w, 1624w, 1592w, 1573w,
1503s, 1423m, 1346m, 1310w, 1243w, 1171m, 1142w, 1097w, 1013s,
984s, 863m, 843m, 732m, 635w, 623w.
Under the same condition were obtained Nd(OC6F5)3(phen) (11)
(yield 92%). Anal. Calcd for C30NdH8F15N2O3 (873.61): Nd, 16.51.
Found: Nd, 16.33% and Er(OC6F5)3(phen) (12) (yield 96%). Anal.
Calcd for C30ErH8F15N2O3 (896.63): Er, 18.65. Found: Er, 18.48%. IR
spectra of 11 and 12 are identical to that of 10.
2.3. Preparation of Nd(OC6F5)3 (1)
To a solution of Nd[N(SiMe3)2]3 (0.240 g, 0.37 mmol) in 4 ml
toluene a solution of C6F5OH (0.231 g, 1.25 mmol) in 3 ml toluene
was added. A mixture was stirred for 4 h at ambient temperature,
the formed volatile products were removed by condensation and the
residual solid was dissolved in 7 ml toluene. A solution was filtered,
concentrated to 3 ml and cold to ꢁ10 ꢀC. The light blue microcrys-
talline precipitate was deposited from a solution in 10 h. The product
was washed with hexane and dried in vacuum to give 0.236 g (92%)
of 1; m.p. in a sealed capillary >180 ꢀC (dec.). Anal. Calcd for
2.7. Preparation of Sm(OC6F5)3(phen)2 (13)
To a solution of Sm[N(SiMe3)2]3 (0.384 g, 0.61 mmol) in 4 ml
toluene a solution of C6F5OH (0.386 g, 2.10 mmol) and 1,10-
phenanthroline (0.22 g, 1.22 mmol) in 4 ml toluene was added. A
mixture was stirred for 4 h at ambient temperature, the formed vol-
atile products were removed by condensation in vacuum. The formed
microcrystalline precipitate was washed with hexane and dried in
vacuum to give 0.53 g (85%) of 13; m.p. in a sealed capillary >300 ꢀC
(dec.). Anal. Calcd for C42SmH16F15N4O3 (1059.94): Sm, 14.19. Found:
C
18NdF15O3 (693.41): Nd, 20.80. Found: Nd, 20.65%. IR (Nujol, n/
smꢁ1): 1686w, 1650m, 1617m, 1592m, 1573m, 1503s, 1421m, 1246w,
1172m, 1104w, 1019s, 988s, 862m, 844m, 731m, 629w.
Under the same condition were obtained Tb(OC6F5)3 (2) (yield
87%). Anal. Calcd for C18TbF15O3 (708.09): Tb, 22.44. Found: Tb, 22.51%
and Er(OC6F5)3 (3) (yield 94%). Anal. Calcd for C18ErF15O3 (716.43): Er,
23.34. Found: Er, 23.41%. IR spectra of 2, 3 are identical to that of 1.
Sm, 14.43%. IR (Nujol, n
/smꢁ1): 1650w, 1620w, 1592w, 1571w, 1503s,
1423m, 1243w, 1220w, 1207w, 1172m, 1144m, 1114m, 1104m, 1088m,
1049m, 1014s, 984s, 864m, 840m, 765m, 731m, 677m, 634w, 626w.
Under the same condition were obtained Tb(OC6F5)3(phen)2
(14) (yield 75%). Anal. Calcd for C42TbH16F15N4O3 (1068.5): Tb,
14.87. Found: Tb, 15.16% and Ho(OC6F5)3(phen)2 (15) (yield 80%).
Anal. Calcd for C42HoH16F15N4O3 (1074.51): Ho, 15.35. Found: Ho,
15.65%. IR spectra of 14 and 15 are identical to that of 13.
2.4. Preparation of Nd(OC6F5)3(Et2O)3 (4)
A mixture of Nd[N(SiMe3)2]3 (0.313 g, 0.50 mmol) and C6F5OH
(0.3 g,1.63 mmol) in 7 ml of diethyl ether was stirred for 2 h at room
temperature. A reaction solution was concentrated to 3 ml, cooled
to ꢁ10 ꢀC and kept at this temperature for a night. The formed pale
blue crystals were separated by decantation, washed with hexane
and dried in vacuum to give 0.36 g (79%) of 4. Anal. Calcd for
2.8. Preparation of Eu(OC6F5)3(phen)2(Et2O) (16)
To a solution of Eu[N(SiMe3)2]3 (0.082 g, 0.13 mmol) in 5 ml
diethyl ether a solution of C6F5OH (0.072 g, 0.391 mmol) and 1,10-
phenanthroline (0.047 g, 0.261 mmol) in 5 ml diethyl ether was
added. The pale pink microcrystalline precipitate was deposited
from a solution in 1 h. The solution was decanted from the pre-
cipitate. The formed microcrystalline precipitate was washed with
hexane and dried in vacuum to give 0.117 g (80%) of 16. Anal. Calcd
for C46EuH26F15N4O4 (1135.66): Eu, 13.38. Found: Eu, 13.65%. IR
C
30NdH30F15O6 (915.77): Nd, 15.75. Found: Nd, 15.57%. IR (Nujol, n/
smꢁ1): 1656w, 1630w, 1505s, 1248w, 1173m, 1131w, 1090w, 1020s,
988s, 871m, 844m, 671m, 655m, 630w, 570w.
Under the same condition were obtained Eu(OC6F5)3(Et2O)2 (5)
(yield 62%). Anal. Calcd for C26EuH20F15O5 (849.37): Eu, 17.89.
Found: Eu, 17.73%; Tb(OC6F5)3(Et2O)3 (6) (yield 87%). Anal. Calcd for
C
30TbH30F15O6 (930.46): Tb, 17.08. Found: Tb, 16.82%; Er(OC6
-
F5)3(Et2O)3 (7) (yield 88%). Anal. Calcd for C30ErH30F15O6 (938.79):
Er, 17.81. Found: Er, 17.90% and Gd(OC6F5)3(Et2O)3 (8) (yield 94%).
Anal. Calcd for C30GdH30F15O6 (928.78): Gd, 16.93. Found: Gd,
16.77%. IR spectra of 5, 6, 7, 8 are identical to that of 4.
(Nujol, n
/smꢁ1): 1650w, 1626w, 1592w, 1577w, 1503s, 1425m,
1245m, 1223w, 1210w, 1175m, 1145m, 1103m, 1090w, 1015s, 988s,
864m, 844m, 758w, 731m, 638w, 626w.
Under the same condition were obtained Yb(OC6F5)3(phe-
n)2(Et2O) (17) (yield 98%). Anal. Calcd for C46YbH26F15N4O4 (1156.74):
Yb,14.96. Found: Yb,15.24%. IR spectrumof 17 isidenticaltothatof 16.
2.5. Preparation of Nd(OC6F5)3(MeOH)3 (9)
To powder of Nd[N(SiMe3)2]3 (0.275 g, 0.44 mmol) a solution of
C6F5OH (0.244 g, 1.33 mmol) in 7 ml methanol was added and the
mixture was stirred for 4 h at 55 ꢀC. A solution was concentrated to
2 ml and cold to 5 ꢀC. The light blue microcrystalline precipitate was
deposited from a solution in 10 h. The product was washed with
2.9. Preparation of Eu(OC6F5)3(phen)(Et2O)3 (18)
To a solution of Eu[N(SiMe3)2]3 (0.092 g, 0.145 mmol) in 5 ml
diethyl ether a solution of C6F5OH (0.08 g, 0.435 mmol) and 1,10-
phenanthroline (0.026 g, 0.144 mmol) in 5 ml diethyl ether was
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A.A. Maleev et al. / Journal of Organometallic Chemistry xxx (2013) 1e7
3
added. The pale pink microcrystalline precipitate was deposited
from a solution in 1 h. The solution was decanted from the pre-
cipitate. The formed microcrystalline precipitate was washed with
hexane and dried in vacuum to give 0.147 g (92%) of 18. Anal. Calcd
for C42EuH38F15N2O6 (1103.7): Eu, 13.77. Found: Eu, 13.65%. IR
capillary >140 ꢀC (dec.). Anal. Calcd for C43TbH25F15N5O3 (1103.59):
Tb, 14.40. Found: Tb, 14.42%. IR (Nujol,
/smꢁ1): 1688w, 1648m,
1600m, 1511s, 1243m, 1220w, 1173m, 1158m, 1115w, 1070m, 1036m,
1017s, 990s, 883m, 756m, 701m, 632m, 625m.
n
(Nujol,
n
/smꢁ1): 1650w, 1626w, 1592w, 1578w, 1510s, 1425m,
2.13. Preparation of Tb(OC6F5)3(bpy)2 (26)
1245m, 1222w, 1208w, 1177m, 1146m, 1104m, 1090w, 1017s, 989s,
864m, 844m, 758w, 731m, 638w, 626w.
The mixture Tb[N(SiMe3)2]3 (0.205 g, 0.32 mmol), C6F5OH
(0.177 g, 0.96 mmol) and 2,20-bipyridyl (0.115 g, 0.638 mmol) in
10 ml toluene was dissolved. The white microcrystalline precipitate
was deposited from a solution in 5 min. The solution was decanted
from the precipitate. The formed microcrystalline precipitate was
washed with toluene and dried in vacuum to give 0.334 g (98%) of
26; m.p. in a sealed capillary >190 ꢀC (dec.). Anal. Calcd for
Under the same condition were obtained Nd(OC6F5)3(phe-
n)(Et2O)3 (19) (yield 96%). Anal. Calcd for C42NdH38F15N2O6
(1095.98): Nd, 13.16. Found: Nd, 13.34%; Ce(OC6F5)3(phen)(Et2O)3
(20) (yield 97%). Anal. Calcd for C42CeH38F15N2O6 (1091.85): Ce,
12.83. Found: Ce, 13.12% and Dy(OC6F5)3(phen)(Et2O)3 (21) (yield
94%). Anal. Calcd for C42DyH38F15N2O6 (1114.24): Dy, 14.58. Found:
Dy, 14.32%. IR spectra of 19e21 are identical to that of 18.
C
38TbH16F15N4O3 (1020.46): Tb, 15.57. Found: Tb, 15.15%. IR (Nujol,
n
/smꢁ1): 1650m, 1600m, 1577m, 1567m, 1510s, 1485m, 1320m,
2.10. Preparation of Sm(OC6F5)3(phen)2(H2O) (22)
1245m, 1175m, 1158m, 1117w, 1104w, 1062w, 1017s, 986s, 766m,
739m, 698w, 670w, 653w, 644w, 625w, 575w.
Crystallization of 13 (0.150 g, 0.142 mmol) from 5 ml benzene in
air led to formation of the colorless crystalline precipitate which
was washed with hexane and dried in vacuum to give 0.115 g (75%)
of 22. Anal. Calcd for C42SmH18F15N4O4 (1077.95): Sm, 13.95. Found:
Under the same condition were obtained Yb(OC6F5)3(bpy)2 (27)
(yield 93%). Anal. Calcd for C38YbH16F15N4O3 (1034.57): Yb, 16.73.
Found: Yb, 16.94%. IR spectrum of 27 is identical to that of 26.
Sm, 14.12%. IR (Nujol, n
/smꢁ1): 3655w, 3625w, 3577w, 3390w,
2.14. X-ray crystallography
3336w, 1651w, 1626m, 1593m, 1576m, 1503s, 1425m, 1262w,
1243w, 1223w, 1168m, 1144m, 1122w, 1104m, 1090w, 1015s, 986s,
927w, 892w, 864m, 844m, 805w, 731m, 637w, 623w.
The complex Ho(OC6F5)3(phen)2(H2O) (23) was prepared from
15 according to the above method (yield 89%). Anal. Calcd for
The X-ray data were collected on a Smart Apex diffractometer
(for 7 and 24, graphite-monochromator, MoKa-radiation,
u
-scan
¼ 0.71073 A, T ¼ 100(2) K) and an Agilent Xcalibur E
diffractometer (for 22 and 23, graphite-monochromator, MoKa-ra-
ꢀ
technique,
l
ꢀ
diation,
u-scan technique,
l
¼ 0.71073 A, T ¼ 100(2) K). SADABS [11]
C
42HoH18F15N4O4 (1092.52): Ho, 15.10. Found: Ho, 15.32%. IR spec-
(7 and 24) and ABSPACK (CrysAlis Pro) [12] (22 and 23) were used to
perform area-detector scaling and absorption corrections. SAINT
[13] (7 and 24) and Data Collection, Reduction and Correction
Program, CrysAlis Pro e Software Package, Agilent Technologies
(2012) [14] (22 and 23) were used to integration of experimental
data. The structures were solved by direct methods and were
refined on F2 using SHELXTL [15] package. All hydrogen atoms were
placed in calculated positions and were refined in the riding model.
trum 23 is identical to that of 22.
2.11. Preparation of Gd(OC6F5)3(phen)2(MeOH) (24)
To a solution of 8 (0.108 g, 0.12 mmol) in 3 ml methanol a solution
of 1,10-phenanthroline (0.045 g, 0.25 mmol) in 3 ml methanol was
added. A mixture was stirred for 4 h at 60 ꢀC. A solution was
concentrated to 3 ml and cold to 5 ꢀC. The colorless microcrystalline
precipitate was deposited from a solution in 10 h. The colorless
crystalline precipitate was washed with hexane and dried in vacuum
to give 0.103 g (82%) of 24. Anal. Calcd for C43GdH20F15N4O4
3. Results and discussion
(1098.87): Gd, 14.31. Found: Gd, 14.52%. IR (Nujol, n
/smꢁ1): 3686,
3.1. Synthesis
3648m, 3607m, 3330m, 1688w, 1650m, 1619m, 1592m, 1574m,
1500s, 1421m, 1258m, 1245m, 1221w, 1206w, 1173m, 1144w, 1104w,
1087w, 1047w, 1017s, 990s, 863m, 844m, 810w, 774w, 732m, 628w.
The reactions of amides Ln[N(SiMe3)2]3 easy proceeded at room
temperature in benzene or toluene to give non-solvated penta-
fluorophenolates in high yield. The same reactions in ether or
methanol afforded Et2O or MeOH solvated complexes.
PhH, PhCH3
Ln(OC6F5)3
Ln = Nd (1),Tb (2), Er (3)
Et2O
Ln[N(SiMe3)2]3
3 HOC6F5
Ln(OC6F5)3(Et2O)3
- 3 HN(SiMe3)2
Ln = Nd (4), Eu (5), Tb (6),
Er (7), Gd (8)
MeOH
Nd(OC6F5)3(MeOH)3 (9)
2.12. Preparation of Tb(OC6F5)3(py)5 (25)
The mixture of Tb[N(SiMe3)2]3 (0.218 g, 0.34 mmol) and C6F5OH
(0.188 g, 1.021 mmol) in 5 ml pyridine was dissolved. The white
microcrystalline precipitate was deposited from a solution by slow
condensation in vacuum. The precipitate was washed with hexane
and dried in vacuum to give 0.363 g (97%) of 25; m.p. in a sealed
The products were isolated as colorless or pale colored highly hy-
groscopic crystalline products readily soluble in benzene, ether and
THF. TGA and DSC analysis revealed that decomposition of
Ln(OC6F5)3 complexes begins at about 140 ꢀC. The complexes 4e9
lose the molecules of solvating Et2O or MeOH above 60 ꢀC. Heating
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A.A. Maleev et al. / Journal of Organometallic Chemistry xxx (2013) 1e7
of the products in dynamic vacuum at 150 ꢀC resulted in formation
LnF3 and octofluorodibenzo-p-dioxine, which was collected on the
cold walls of the vessel as colorless crystals characterized struc-
turally. Similar scheme of dioxine formation from perfluorinated
phenols was described earlier [16].
bipyridyl ligands not only enhanced the decomposition tempera-
ture of the perfluorinated phenolates but as well decreased their
hygroscopisity. The addition of water was not observed after
exposition of the products in air for 10 h.
In attempt to increase the thermostability and decrease the
hygroscopicity of the phenolates we closed the coordination sphere
of Ln3þ ions by ancillary 1,10-phenanthroline ligands which could
prevent the intramolecular F / Ln coordination (anticipating the
fluorine migration) and water solvolysis. The phenanthroline con-
taining complexes were obtained in two ways: (a) by stirring of a
mixture of Ln(OC6F5)3 and phenanthroline in benzene or toluene
and (b) the reaction of Ln[N(SiMe3)2]3 with pentafluorophenol in
toluene in the presence of phenanthroline.
3.2. Structures
The molecular structure of 7 is depicted in Fig. 1. According to X-
ray analysis data complex 7 adopts a monomeric structure where
erbium atom is bounded by three pentafluorophenolate ligands
and three molecules of diethyl ether. There are three independent
molecules of complex 7 in asymmetric unit. One molecule lies in
common position whereas other molecules are disposed on C2 axes.
These molecules have similar geometrical parameters. The Er atom
F
F
F
F
+ n Phen
a)
b)
Ln(OC6F5)3
F
O
F
F
F
N
N
F
O
Ln
O
F
n
Ln[N(SiMe3 ] +
+ n Phen
F
5
)
2 3
3 HOC6
F
F
F
n= 1-2
F
F
Depending on molar ratio of initial reagents the resulting
complexes contain one (10e12) or two (13e15) molecules of phe-
nanthroline. The same reactions in the ether or methanol solution
afforded the products containing both neutral ligands e phenan-
throline and ether (16e21) or MeOH (24). Crystallization of 13 and
15 from benzene in air led to formation of water containing com-
plexes 22 and 23. Besides 1,10-phenanthroline, the pyridine and
bipyridyl were used as the neutral coordinately bonded ligands.
The pyridinate 25 was isolated in 97% yield from the reaction Tb
[N(SiMe3)2]3 with C6F5OH in pyridine solution. The bipyridyl con-
taining products 26 and 27 were obtained similarly to their phe-
nanthroline analogs from silylamides, phenol and bipyridyl in
toluene medium.
As expected, the complexes with phenanthroline ligands 10e15
displayed significantly higher decomposition temperature (above
300 ꢀC) than their phenanthroline free counterparts. Upon heating
in vacuum the compounds sublimed without decomposition. The
effect of increasing the stability was also observed when the phe-
nolates were coordinated with pyridine and bipyridyl (compounds
25e27). The additional coordination of Et2O molecules to phe-
nanthroline containing compounds 10e15 led to some decrease in
thermal stability of the formed products 16e21 due to the easily
proceeding ether cleavage. The ancillary phenanthroline or
Fig. 1. Molecular structure of Er(OC6F5)3(Et2O)3 (7). Thermal ellipsoids are drawn at
ꢀ
ꢀ
the 30% probability level. Selected distances [A] and angles [ ]: EreO(1) 2.117(2), Ere
O(2) 2.139(2) EreO(3) 2.168(2), EreO(4) 2.321(2), EreO(5) 2.326(2), EreO(6) 2.408(2);
O(1)eEreO(2) 94.79(9), O(1)eEreO(3) 94.65(8), O(1)eEreO(4) 95.56(8), O(1)eEre
O(5) 91.52(8), O(1)eEreO(6) 176.02(7).
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A.A. Maleev et al. / Journal of Organometallic Chemistry xxx (2013) 1e7
5
has a distorted meridional octahedral environment. The Ere
O(OC6F5) and EreO(Et2O) distances vary in the range of 2.117(2)e
ꢀ
ꢀ
2.168(2) A and 2.321(2)e2.408(2) A respectively. In complex 7,
there are EreO(OC6F5) bonds trans to both phenolate and neutral
Et2O molecules, and there appears to be a slight but statistically
significant dependence of LneO bond length upon the identity of
the trans ligands. The EreO(OC6F5) bonds that are trans to phe-
ꢀ
ꢀ
nolates (2.139(2), 2.168(2) A) are longer by 0.022 and 0.051 A than
ꢀ
in the LneO phenolate bond trans to Et2O (2.117(2) A). The same
trends are noted in the bonds to Et2O, where the LneO(Et2O) bond
ꢀ
ꢀ
ꢀ
trans to the phenolate 2.408(2) A is 0.087 A and 0.082 A longer than
ꢀ
ꢀ
the LneO bonds trans to Et2O (2.321(2) A, 2.326(2) A). The analo-
gous trend is observed in complex (THF)3Yb(OC6F5)3 [4]. This
phenomenon of the trans effect was also noted in the thiolates and
selenolates (THF)3Ln(EC6F5)3 (Ln ¼ Er, Yb; E ¼ S, Se) [17]. According
to DFT calculations of these complexes the LneE interactions have a
covalent nature.
Complexes 22e24 have similar molecular structure (Fig. 2).
According to X-ray analysis the Ln atoms in 22e24 is bounded by
three pentafluorophenolate ligands, two 1,10-phenanthroline
molecules and oxygen atom (H2O in 22, 23 and MeOH in 24).
Thus a coordination numbers of Ln atoms in these complexes are
equal 8. The LneO(OC6F5) bond lengths range from 2.2597(8) to
ꢀ
ꢀ
2.3254(7) A in 22, from 2.2241(9) to 2.2642(8) A in 23 and from
ꢀ
2.236(2) to 2.261(2) A in 24. The LneN(1,10-phenanthroline) dis-
tances are 2.6034(10)e2.6656(9), 2.5482(8)e2.6112(9)
ꢀ
A
and
ꢀ
2.589(3)e2.660(3) A, respectively in 22e24. The main difference
between complexes 22e24 is reciprocal disposition of ligands and
neutral molecules in coordination sphere of Ln. In complex 22, only
two pentafluorophenolate ligands have face to face disposition
relative to two 1,10-phenanthroline molecules whereas in com-
plexes 23 and 24 all pentafluorophenolate ligands have approxi-
mately face to face disposition relative to two 1,10-phenanthroline
molecules.
Two pentafluorophenolate ligands (O(2)C5F5 and O(3)C5F5) in
22 are practically parallel 1,10-phenanthroline molecules (N(1)N(2)
C
12H8 and N(3)N(4)C12H8). The dihedral angles between appro-
priate planes are 16.1ꢀ and 17.0ꢀ. The distances between centers of
pentafluorophenolate ligands (A) and pyridine fragments (B) of
ꢀ
ꢀ
1,10-phenanthroline molecules are 3.445 A and 3.624 A (Fig. 2a).
Such distances allow supposing the presence of
pep interactions
between them [17]. Hereupon the Sm(1)O(2)C(7) (143.12(7)ꢀ) and
Sm(1)O(3)C(13) (142.69(7)ꢀ) bond angles are significantly less as
compared to the Sm(1)O(1)C(1) (174.17(7)ꢀ) bond angle. It should
ꢀ
be noted that the Sm(1)eO(2) (2.2980(7) A) and Sm(1)eO(3)
ꢀ
ꢀ
(2.3254(7) A) distances exceed the Sm(1)eO(1) (2.2597(8) A) bond.
As above mentioned all pentafluorophenolate ligands have
approximately face to face disposition relative to two 1,10-
phenanthroline molecules in 23. The dihedral angles between
planes B and D, A and D, C and E are 40.7ꢀ, 21.3ꢀ and 41.6ꢀ,
respectively (Fig. 2b). The distances between centers of penta-
fluorophenolate ligands (A, B and C) and pyridine fragments (D and
2.6230(9), O(1)eSm(1)eO(2) 96.36(3), O(1)eSm(1)eO(3) 121.75(3), O(1)eSm(1)e
O(1S) 77.58(3), O(1)eSm(1)eN(1) 79.83(3), O(1)eSm(1)eN(2) 140.80(3), O(1)eSm(1)e
N(3) 129.19(3), O(1)eSm(1)eN(4) 76.01(3); in 23: Ho(1)eO(1) 2.2425(8), Ho(1)eO(2)
2.2241(9), Ho(1)eO(3) 2.2642(8), Ho(1)eO(1S) 2.3749(9), Ho(1)eN(1) 2.5923(8),
Ho(1)eN(2) 2.5714(9), Ho(1)eN(3) 2.6112(9), Ho(1)eN(4) 2.5482(8), O(1)eHo(1)eO(2)
103.51(3), O(1)eHo(1)eO(3) 144.55(3), O(1)eHo(1)eO(1S) 85.80(3), O(1)eHo(1)eN(1)
137.18(3), O(1)eHo(1)eN(2) 74.56(3), O(1)eHo(1)eN(3) 74.74(3), O(1)eHo(1)eN(4)
76.98(3); in 24: Gd(1)eO(1) 2.236(2), Gd(1)eO(2) 2.258(2), Gd(1)eO(3) 2.261(2),
Gd(1)eO(4) 2.451(2), Gd(1)eN(1) 2.645(3), Gd(1)eN(2) 2.628(3), Gd(1)eN(3) 2.660(3),
Gd(1)eN(4) 2.589(3), O(1)eGd(1)eO(2) 144.75(8), O(1)eGd(1)eO(3) 96.02(8), O(1)e
Gd(1)eO(4) 91.47(7), O(1)eGd(1)eN(1) 139.12(8), O(1)eGd(1)eN(2) 76.53(8), O(1)e
Gd(1)eN(3) 72.44(8), O(1)eGd(1)eN(4) 86.42(8).
Fig. 2. Molecular structure of Sm(OC6F5)3(phen)2(H2O), 22 (a); Ho(OC6F5)3(-
phen)2(H2O), 23 (b); Gd(OC6F5)3(phen)2(MeOH), 24 (c). Thermalꢀellipsoids are drawn
ꢀ
at the 30% probability level. Selected distances [A] and angles [ ] in 22: Sm(1)eO(1)
2.2597(8), Sm(1)eO(2) 2.2980(7), Sm(1)eO(3) 2.3254(7), Sm(1)eO(1S) 2.606(1),
Sm(1)eN(1) 2.6656(9), Sm(1)eN(2) 2.603(1), Sm(1)eN(3) 2.6487(9), Sm(1)eN(4)
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6
A.A. Maleev et al. / Journal of Organometallic Chemistry xxx (2013) 1e7
Table 1
Absorption and luminescence spectra of pentafluorophenolates of Sm, Eu, Tb, Dy, Er
and Yb complexes in MeCN solution at room temperature (L ¼ OC6F5).
Complex (no.)
labs, nm
lem, nm
lex, nm Q.Y.
Sm(L)3(phen)2 (13)
266, 342
405, 564, 600,a 360
645
0.9
Eu(L)3(Et2O)3 (5)
Eu(L)3(phen)2(Et2O) (16) 266, 340
Tb(L)3 (2)
Tb(L)3(phen)2 (14)
267, 340
405, 618a
415, 618a
400
310
340
340
<0.01
<0.01
0.4
260, 340
264, 340
415, 490, 550,a 360
590, 625
0.05
Tb(L)3(bpy)2 (26)
266, 315
415, 490, 550a, 320
590, 625
0.1
Dy(L)3(phen)(Et2O)3 (21) 266, 327, 340
415
350
340
1.5
1.0
Er(L)3 (3)
261, 378, 521, 400
740, 780
Fig. 3. The disposition of solvate molecule of 1,10-phenanthroline in complex 23.
Thermal ellipsoids are drawn at the 30% probability level. The pentafluorophenolate
ligands are omitted for clarity.
Er(L)3(Et2O)3 (7)
267, 379, 520, 420
1450
310
350
<0.05
<0.05
Yb(L)3(phen)(Et2O) (17)
266, 326
410
a
Band used to determine quantum yield (Q.Y.).
ꢀ
ꢀ
E) of 1,10-phenanthroline molecules are 3.442 A, 3.994 A and
ꢀ
4.070 A (Fig. 2b). It should be noted that only one distance between
with the realization possibility of intramolecular pep interactions
ꢀ
centers of
p
-systems (3.442 A) clearly satisfies the geometrical
between them. Also such disposition of solvate molecule of 1,10-
phenanthroline additionally is stabilized the N/H(H2O) in-
teractions (Fig. 3). The N(1S, 2S)/H(H2O) distances are 2.01 and
criterion about the presence of
p
e
p
interaction between them
ꢀ
ꢀ
(3.8 A) [17]. However all HoOC bond angles (137.67(8)e143.23(7) )
are close to the Sm(1)O(2)C(7) and Sm(1)O(3)C(13) bond angles in
22 where appropriate pentafluorophenolate ligands take part in
ꢀ
2.05 A.
In common with 22, complex 24 does not contain solvate mol-
ecules. However the reciprocal disposition of pentafluorophenolate
ligands and 1,10-phenanthroline molecules relative to each other in
24 is similar to 23. The dihedral angles between planes C and E, B
intramolecular
pep interactions. As distinct from 22, complex 23
contains two solvate molecules in asymmetric unit (benzene and
1,10-phenanthroline). The solvate molecule of 1,10-phenanthroline
has offset disposition relative to coordinated 1,10-phenanthroline
molecule (Fig. 3). The dihedral angle between planes of these
molecules is 7.8ꢀ. The distances between centers of benzene frag-
ꢀ
ments of 1,10-phenanthroline molecules is 3.765 A that is agreed
Fig. 5. Excitation and emission spectra of Sm(OC6F5)3(phen)2 (13) (a) and
Tb(OC6F5)3(bpy)2 (26) (b) in MeCN solution at room temperature.
Fig. 4. Absorption spectra of Nd(OC6F5)3 (1) (a) and Er(OC6F5)3(Et2O)3 (7) (b).
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A.A. Maleev et al. / Journal of Organometallic Chemistry xxx (2013) 1e7
7
and D, A and D are 31.8ꢀ, 51.3ꢀ and 14.7ꢀ, respectively. The distances
between centers of pentafluorophenolate ligands (A, B and C) and
pyridine fragments (D and E) of 1,10-phenanthroline molecules are
emissive layers for the OLED devices by vacuum sublimation or
spin-coating method and investigate their electroluminescent
properties. These data will be published elsewhere.
ꢀ
ꢀ
3.612 Å, 3.994 A and 4.238 A (Fig. 2c). As with 23 only one distance
ꢀ
(3.612 A) between center of
p-systems satisfies the condition of
Acknowledgments
intramolecular interactions.
pep
This work was partially supported by the Russian Foundation for
Basic Research (grants No. 13-03-00097, 13-03-00891, 12-03-31273,
12-03-31474, 13-03-97046) and the Ministry of Education and
Science of the Russian Federation (agreement 8637).
3.3. Luminescence properties
Absorption spectra of the obtained complexes in THF or MeCN
solutions are dominated by spin allowed pep* transitions of OC6F5
at 267 with poorly resolved shoulder at 350 nm caused by ab-
sorption of ancillary ligands. Besides, in the cases of 1 and 7 the
bands of respectively Nd3þ and Er3þ ions were observed (Fig. 4)
which are consistent with previously published data [4].
The excitation spectra of the 13 and 26 monitored at 600 and
550 nm, respectively, are dominated by the strong broad band in
the UV region that corresponds to the excitation of the organic
chromophore (S0eS1) (Table 1). The excitation bands of fef tran-
sitions are too weak to be registered.
Appendix A. Supplementary material
CCDC 924233 (7), 924234 (22), 924235 (23), 924236 (24)
contain the supplementary crystallographic data for this paper.
These data can be obtained free of charge via www.ccdc.cam.ac.uk/
data_request/cif.
Appendix B. Supplementary material
The emission spectra were measured only in the UVevisible
region because of the limitation of the used tool. In THF or MeCN
solution the complexes exhibited the luminescence of the ligands
as a broad band at 405e415 nm. The spectra of Sm (13), Eu (5, 16,
18), and Tb (14, 25, and 26) complexes contained also narrow bands
of metal-centered emission: 560, 600, 650 nm of 4G5/2e6Hj (j ¼ 5/2,
7/2, 9/2) transitions for Sm3þ, 618 nm of 5D0e7F2 transition for Eu3þ
and 490, 550, 580, 660 nm of 5D4e7FJ (J ¼ 6e3) transitions for Tb
complexes (Fig. 5).
The quantum efficiency of obtained fluorinated phenolates is
considerably lower than literature values for similar phenolates of
Nd, Er and Tm emitting in NIR region [4] and is comparable with the
efficiency of more traditional coordination compounds of these
lanthanides.
Supplementary data related to this article can be found at http://
dx.doi.org/10.1016/j.jorganchem.2013.03.052.
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