Cyclopalladized complexes on the matrix of phenyland naphthyl-derivatives of oxazole and oxazoline with ethylenediamine

Full text of DOI:10.1134/S1070363210020337

ISSN 1070-3632, Russian Journal of General Chemistry, 2010, Vol. 80, No. 2, pp. 370–371. © Pleiades Publishing, Ltd., 2010.
Original Russian Text © O.A. Rodionova, G.O. Finagenova, M.V. Puzyk, K.P. Balashev, 2010, published in Zhurnal Obshchei Khimii, 2010, Vol. 80, No. 2,
pp. 343–344.
LETTERS
TO THE EDITOR
Cyclopalladized Complexes on the Matrix of Phenyl-
and Naphthyl-Derivatives of Oxazole and Oxazoline
with Ethylenediamine
O. A. Rodionova, G. O. Finagenova, M. V. Puzyk, and K. P. Balashev
Herzen Russian State Pedagogical University,
nab. R. Moyki 48, St. Petersburg, 191186 Russia
e-mail: balashevk@mail.ru
Received April 27, 2009
DOI: 10.1134/S1070363210020337
1
The aryl-substututed derivatives of oxazole belong
to effective organic luminophors used as the activating
additives in the liquid and plastic scintillators [1]. At
the same time the reaction of phenyl- and naphthyl-
substituted oxazoles with the compounds of Pt(II) and
Ir(III) [2, 3] results in their cyclometallation that
changes sufficiently their optical properties.
The results of Н NMR (CD3CN) and IR (KBr)
spectroscopy confirm the composition of complexes
obtained in solution and in solid phase. The cyclo-
palladization leads not only to the deprotonation of
phenyl and naphthyl substituents of oxazole and
oxazoline ligands, but to the magnetic nonequivalence
of amine protons of ethylenediamine due to the
difference in the trans-effect of the donor atoms N and
С of cyclometallated ligand. The IR spectra of com-
plexes are characterized by both low-frequency shift of
the stretching С=N vibrations of heterocyclic ligand
and characteristic [4–6] change in the out-of-plane
bending С–Н vibrations as a result of metallation of
phenyl or naphthyl groups.
In the present work the results on synthesis and
study of spectral properties are presented of the
cyclopalladized complexes [Pd(C^N)En]ClO4 on the
basis of oxazole and oxazoline derivatives [(C^N)–,
deprotonated forms of 2-phenyl-2-oxazoline (pho–),
2,5-diphenyloxazole (dpo–), 2-(1-naphthyl)-5-phenyl-
oxazole (npo–), 2-phenylbenzoxazole (bo–); En is 1,2-
diaminoethane].
Ph
Ph
O
N
O
O
N
O
4
−C
pho−
−C
N
−C
dpo−
−C
N
npo−
bo−
Compared to the free heterocyclic ligands, the
characteristic result of cyclopalladization is the
presence of the long-wave optical transitions in the
absorption and emission electron spectra of complexes,
which are caused [7] by the spin-permitted and spin-
prohibited transitions between the orbitals located on
the metal complex fragment {Pd(C^N)}. Similar to the
cyclometallated complexes of Pd(II), Pt(II), and Ir(III)
on the base of coumarin dye [2, 3, 8], the cyclo-
metallation of 2,5-diphenyloxazole dye leads to
increasing efficiency of the intercombination conver-
sion of singlet excited states into triplet due to the
increase in the spin-orbital interaction in the metal
complex {M(dpo)} fragments. It determines the logical
decrease in the fluorescence intensity in the series
Hdpo > {Pd(dpo)} > {Pt(dpo)} = {Ir(dpo)2}.
370

CYCLOPALLADIZED COMPLEXES ON THE MATRIX
371
1
Syntheses of the cyclopalladized complexes were
carried out by the general procedure [9] involving the
dimer complexes [Pd(C^N)(μ-CH3COO)] preparation
on refluxing of palladium acetate with equivalent
amount of the heterocyclic ligand H(C^N) in the acetic
acid solution. The subsequent substitution of the bridge
acetate ligands with ethylenediamine in methanol and
the precipitation of the reaction product with sodium
perchlorate gave rise to the precipitation of [Pd(C^N)En]·
ClO4 from solution. The precipitate was filtered off,
washed with cold methanol, ether, and dried in air.
Yield 60–70%.
palladium(II) perchlorate [Pd(bo)En]ClO4. Н NMR
spectrum (CDCN3) ), δ, ppm: 7.71 m, 7.70 d.d (3JHH
4
6.9 Hz, JHH 2.1 Hz), 7.51 m (2Н), 7.40 m, 7.31 d.t
(3JHH 7.4 Hz, JHH 1.8 Hz), 7.28 d (3JHH 7.3 Hz, JHH
4
4
1.3 Hz), 7.13 d.d (3JHH 7.0 Hz, JHH 1.6 Hz). IR
4
spectrum (KBr), ν, cm–1: 1611 (C=N), 739 (C6H4).
Absorption spectrum (CH3CN), λmax, nm (ε×10–33
,
mol–1 cm–1): 233 pl (19.8), 296 pl (10.4), 308 pl (9.3),
346 (7.0), 364 (4.6). Phosphorescence parameters (77
K, DMFA:toluene, 1:1), λmax, nm, (τ, μs): 488, 523,
546, 557 (120).
1
The Н NMR and electron absorption spectra were
(2-Phenyl-3-ido)-2-oxazolinethylenediamine
obtained on JNM-ECX400A and SF-2000 spectro-
meters respectively at 293K in CD3CN and CH3CN
solutions. The IR spectra were recorded on a Shimadzu
IR Prestige–21 spectrophotometer (KBr). The lumine-
scence was studied in the glassy solutions
DMF:toluene (1:1) at 77 K on a KSBU-1 device using
a FEU-100 photoelectronic multiplier and impulse
laser photoexcitation LGI-21 (λ = 337 nm, τ = 10 ns)
as described earlier [10]. The fluorescence spectra
were registered at 298 K in CH3CN solutions on a
FLUORAT-PANORAMA spectrofluorometer.
1
palladium(II) perchlorate [Pd(pho)En]ClO4. Н NMR
spectrum (CDCN3), δ, ppm: 7.28 d.d (3JHH 7.4 Hz, 4JHH
4
1.5 Hz), 7.21 d.t (3JHH 7.4 Hz, JHH 1.5 Hz), 7.13 d.t
4
4
(3JHH 7.4 Hz, JHH 1.5 Hz), 7.02 d.d (3JHH 7.4 Hz, JHH
1.5 Hz), 4.77 d.d (3JHH 9.6, 9.4 Hz), 4.01 m (2Н), 3.86
d.d (3JHH 9.6, 9.4 Hz), 3.25 m (2Н), 2.83 m (2Н), 2.76
m (2Н). IR spectrum (KBr), ν, cm–1: 1647 (C=N), 741
(C6H4). Absorption spectrum (CH3CN), λmax, nm
(ε×10–3, mol–1 cm–1): 229 (29.0), 296 (6.5), 330 (3.0).
Phosphorescence parameters (77 K, DMF:toluene,
1:1), λmax, nm, (τ, μs): 448, 480, 520, 560 40).
REFERENCES
(2-Phenyl-3-ido)-5-phenyloxazolethylenediamine
1
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7.62 m, 7.61 s, 7.53 t (3JHH 8.0 Hz; 2H), 7.48 d.d (3JHH
7.4, 6.5 Hz), 7.25 m (2Н), 7.09 m. IR spectrum (KBr),
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,
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4
4
7.3 Hz, JHH 1.2 Hz), 8.10 d.d (3JHH 8.2 Hz, JHH
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7.4 Hz), 7.66 t (3JHH 7.7 Hz), 7.62 s, 7.51 m, 7.33 d.d
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287 pl (14.6), 348 pl (14.2), 368 (20.6), 387 (18.1).
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1:1), λmax, nm, (τ, μs): 573, 620 (40).
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(2-Phenyl-3-ido)-benzoxazolethylenediamine
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 80 No. 2 2010