Platinum(II) complexes with π-conjugated, naphthyl-substituted, cyclometalated ligands (RC∧N∧N): Structures and photo- and electroluminescence

Article abstract of DOI:10.1002/chem.200600686

The crystal structures and photophysical properties of mononuclear [(RC∧N∧N)PtX](ClO₄)_n ((RC∧N∧N) = 3-(6′-(2″-naphthyl)-2′-pyridyl)isoquinolinyl and derivatives; X = Cl, n = 0; X = PPh₃ or PCy₃, n = 1), dinuclear [(RC∧N∧N)₂Pt₂(μ-dppm)]-(ClO₄) ₂ (dppm = bis(diphenyphosphi-no)methyl) and trinuclear [(RC∧N∧N)₃Pt₃(μ-dpmp)](ClO₄) ₃ (dpmp = bis(diphenylphosphinomethyl)phenylphosphine) complexes are presented. The crystal structures show extensive intra- and/or intermolecular π...π interactions; the two (RC∧N∧N) planes of [(RC∧N∧N)₂Pt₂(μ-dppm)]-(ClO₄) ₂ (R = Ph, 3,5-tBu₂Ph or 3,5-(CF₃) ₂Ph) are in a nearly eclipsed configuration with torsion angles close to 0°. [(RC∧N∧N)PtCl], [(RC∧N∧N)₂Pt ₂-(μ-dppm)](ClO₄)₂, and [(RC∧N∧N) ₃Pt(μ-dpmp)](ClO₄)₃ are strongly emissive with quantum yields of up to 0.68 in CH₂Cl₂ or MeCN solution at room temperature. The [(RC∧N∧N)PtCl] complexes have a high thermal stability (T_d = 470-549°C). High-performance light-emitting devices containing [(RC∧N∧N)PtCl] (R = H or 3,5-tBu ₂Ph) as a light-emitting material have been fabricated; they have a maximum luminance of 63 000 cd m^-2 and CIE 1931 coordinates at x = 0.36, y = 0.54.

Full text of DOI:10.1002/chem.200600686

FULL PAPER
DOI: 10.1002/chem.200600686
Platinum(II) Complexes with p-Conjugated, Naphthyl-Substituted,
Cyclometalated Ligands (RC^N^N): Structures and Photo- and
Electroluminescence
Steven C. F. Kui,[a] Iona H. T. Sham,[a] Cecil C. C. Cheung,[a] Chun-Wah Ma,[a]
Beiping Yan,[a] Nianyong Zhu,[a] Chi-Ming Che,*[a] and Wen-Fu Fu[b]
Abstract: The crystal structures and
photophysical properties of mononu-
p···p interactions; the two (RC^N^N)
planes of [(RC^N^N)2Pt2(m-dppm)]-
(ClO4)2 (R=Ph, 3,5-tBu2Ph or 3,5-
of up to 0.68 in CH2Cl2 or MeCN solu-
tion at room temperature. The
[(RC^N^N)PtCl] complexes have a
ACHTREUNG
clear
[(RC^N^N)PtX]
A
G
((RC^N^N)=3-(6’-(2’’-naphthyl)-2’-
pyridyl)isoquinolinyl and derivatives;
X=Cl, n=0; X=PPh3 or PCy3, n=1),
(CF3)2Ph) are in a nearly eclipsed con-
figuration with torsion angles close to
08. [(RC^N^N)PtCl], [(RC^N^N)2Pt2-
high thermal stability (Td =470–
5498C). High-performance light-emit-
ting
devices
containing
dinuclear
[(RC^N^N)2Pt2
A
N
A
and
(ClO4)3 are
[(RC^N^N)PtCl] (R=H or 3,5-
tBu2Ph) as a light-emitting material
have been fabricated; they have a max-
imum luminance of 63000 cdmÀ2 and
CIE 1931 coordinates at x=0.36, y=
0.54.
A
G
ACHTREUNG
no)methyl)
[(RC^N^N)3Pt3
(dpmp=bis(diphenylphosphinome-
thyl)phenylphosphine) complexes are
presented. The crystal structures show
extensive intra- and/or intermolecular
and
(m-dpmp)]
trinuclear
(ClO4)3
G
ACHTREUNG
OLEDs
·
photoluminescence
·
Introduction
subtle changes in the local environment in which the PtII
complex is located.[1,3,5–11,16,17] Of particular interest is the in-
3
3
Platinum(II) complexes containing aromatic N-donor and/or
cyclometalated ligands are known to display a variety of
emissive excited states, including ligand-field (LF), metal-to-
ligand charge transfer (MLCT), intraligand (IL) p–p*, exci-
meric s*(p)!s(p*), and oligomeric metal–metal-to-ligand
terplay between MLCT/3IL and MMLCT emissive excited
states, which are strongly affected by PtII–PtII and/or ligand–
ligand interactions.[12,13,16–18] Several classes of diplatinum(II)
complexes of the type [Pt
A
(m-L)]n+, [Pt2
U
G
L)]n+ and [(C^N)Pt
A
ACHTREUNG
charge-transfer (MMLCT) ds*
relative energy of these excited states is strongly affected by
A
idyl; (C^N^N)=6-phenyl-2,2’-bipyridyl; L=guanidine, pyr-
azole, azaindole, diphenylformamidine, arginine or bis(di-
phenyphosphino)methyl; (C^N)=2-(2,4-difluorophenyl)pyr-
idyl; pz=pyrazolate derivatives) with intramolecular Pt–Pt
contacts ranging from 2.998 to 3.432 Š are known to be
[a] Dr. S. C. F. Kui, Dr. I. H. T. Sham, C. C. C. Cheung, C.-W. Ma,
Dr. B. Yan, Dr. N. Zhu, Prof. C.-M. Che
Department of Chemistry and the HKU-CAS Joint Laboratory on
New Materials
emissive.[4,13,17–20] However, except for [(C^N)Pt
C
3
A
The University of Hong Kong, Pokfulam Road
Hong Kong Special Administrative Region (China)
Fax : (+852)2857-1586
nuclear PtII complexes have a relatively low emission quan-
tum yield and short lifetime in solution at room tempera-
ture.[9,13,17,20]
E-mail: cmche@hku.hk
[b] Prof. Dr. W.-F. Fu
In the course of our studies on [(C^N^N)PtX] complexes
((C^N^N)=6-phenyl-2,2’-bipyridyl, X=Cl, PPh3, acetylide,
etc.), we have observed that: 1) the (C^N^N) ligand shows
a strong preference for a planar geometry and can therefore
be expected to disfavor the excited-state distortion that pro-
Technical Institute of Physics and Chemistry
Chinese Academy of Science
Peking 100101 (China)
Supporting Information for this article is available on the WWW
under http://www.chemeurj.org/ or from the author.
Chem. Eur. J. 2007, 13, 417 – 435
ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
417

motes radiationless decay;[11,21] 2) the p-conjugation and
strong s-donor strength of the deprotonated carbon donor
of the (C^N^N) ligand increase the energy gap between the
d–d and MLCT excited states;[21–24] and 3) the ability to vary
the ancillary ligand X and ease of modification of the
(C^N^N) ligand are advantageous for structural modifica-
tion of [(C^N^N)PtX] complexes with tuneable photophysi-
cal properties.[12,13,15,16,19,20] We therefore envisioned that the
nolinyl complexes [(RC^N^N)PtX]
1a–1 f; X=PPh3, n=1, 3c; X=PCy3 (Cy=cyclohexyl), n=
1, 4b and 4c), the dinuclear complexes [(RC^N^N)2Pt2(m-
(ClO4)2 (dppm=bis(diphenyphosphino)methyl, 2a–
(m-
(ClO4)3 (dpmp=bis(diphenylphosphinomethyl)phe-
G
dppm)]
dpmp)]
ACHTREUNG
AHCTREUNG
nylphosphine, 5b and 5d; Figure 1) are reported. Complexes
1a and 1d have been tested for the fabrication of OLEDs.
intra-
and
intermolecular
interactions
between
[(C^N^N)Pt]+ moieties could be varied by enhancing non-
covalent p···p interactions through the use of extended p-
conjugated cyclometalated ligands.[16,25] In this work, we
have replaced the 6-phenyl-2,2’-bipyridyl (C^N^N) ligand
with 3-(6’-(2’’-naphthyl)-2’-pyridyl)isoquinolinyl ligands (de-
noted as (RC^N^N) hereafter; Figure 1). The use of extend-
ed p-conjugated aromatic diimine ligands has been reported
Results and Discussion
The series of (RC^N^NH) ligands a–f was synthesized with
product yields of 55–88%. Attempts to prepare
[(RC^N^N)PtCl] by the reaction of (RC^N^NH) with
K2PtCl4 in acetonitrile solution[27] were unsuccessful. Howev-
er, we found that if glacial acetic acid was used as the sol-
vent, 1a–1 f could be obtained in yields of up to 92%
(Scheme 1). The mononuclear complexes 3c, 4b and 4c, di-
nuclear complexes 2a–2 f, and trinuclear complexes 5b and
5d were obtained by stirring [(RC^N^N)PtCl] with the re-
3
to lead to a relatively long-lived MLCT excited state, as in
the case of [Ru
A
yl)pyridyl; dtpH=2,9-bis
A
Here, the synthesis, crystal structures and emissive proper-
ties of the mononuclear 3-(6’-(2’’-naphthyl)-2’-pyridyl)isoqui-
Figure 1. Structures and numbering scheme of ligands a–f as well as complexes 1a–1 f, 2a–2 f, 3c, 4b, 4c, 5b and 5d for NMR peak assignment.
418
www.chemeurj.org
ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2007, 13, 417 – 435

Platinum(II) Complexes with Cyclometalated Ligands
FULL PAPER
Scheme 1. The synthesis of 1a–1 f, 2a–2 f, 3c, 4b, 4c, and 5b. The X and R groups and yields are given in parentheses.
spective PPh3, PCy3, dppm, or dpmp ligand in a MeCN/
CH2Cl2 solution (Scheme 1); they were isolated as ClO4
salts.
of the signals was observed in deuterated MeCN as the tem-
perature was lowered from 0 to À458C. No fluxional behav-
ior was observed for 2a–2 f.
À
The 31P NMR spectrum of 5d reveals two signals at d=
9.7 (central) and 11.7 ppm (terminal) with 195Pt satellites
(1JP,Pt =4042 and 4094 Hz, respectively), and its 195Pt-
Physical characterizations: The FAB-mass spectra reveal
prominent molecular ion [M+] peaks for 1a–1 f,
a
[MÀClO4]+ peak for 3c, 4b, and 4c, [MÀClO4]+ or [MÀ2-
A
A
(ClO4)]+,
(central) and À3886.5 ppm (terminal) with JP,Pt =3995 and
4070 Hz, respectively. The NMR spectroscopic data are con-
sistent with two chemically inequivalent phosphorus atoms
in 5d.[16]
or [MÀ3
U
ing scheme of ligands a–f and complexes 1a–1 f, 2a–2 f, 3c,
4b, 4c, 5b and 5d for NMR peak assignments are depicted
in Figure 1. The spatial relationship of the protons in the
[(RC^N^N)PtCl] complexes was assigned based on the re-
sults of 1H–1H correlation and NOESY 2D NMR experi-
ments.
Thermogravimetric analysis (TGA) revealed that the
[(RC^N^N)PtCl] complexes 1a–1 f decompose at tempera-
tures above 4708C (Td =470–5498C, Table 1). The mononu-
clear complexes with PPh3 or PCy3 ligands (3c, 4b and 4c)
have a lower Td (320–3768C) than their Cl congeners 1a–1 f.
The dinuclear complexes 2a–2 f decompose above 3708C
(Td =376–3858C) and the trinuclear complexes 5b and 5d
decompose at 421 and 3378C, respectively (Table 1). No
glass transition was observed in differential scanning calori-
metric (DSC) studies for 1a–1 f and 2a–2 f in scans up to
4008C, thus indicating that the glass-transition temperatures
(Tg) of these complexes are above 4008C.
The 31P NMR spectra of 2a–2 f show one intense signal
with 195Pt satellites (1JP,Pt ꢀ4250 Hz). Similar findings have
previously been obtained for [(C^N^N)2Pt2
(ClO4)2 (1JP,Pt ꢀ4110 Hz),[16,18,20] [(C^N^C)2Pt2
((C^N^C)=2,6-diphenylpyridyl and derivatives; 1JP,Pt
ꢀ4150 Hz)[28] and [(RC^N^C)2Pt2
ACHTREUNG
2,6-di-(2’-naphthyl)pyridyl
and
ꢀ4250 Hz).[25] There is a close match between the 31P NM R
spectrum of 2d and the simulated spectrum based on an
AA’XX’ system[29] (1JP,Pt =4200 and 2JP,Pt =80 Hz). The two
phosphorus atoms of the Pt-P-CH2-P-Pt bridge in 2a–2 f are
indistinguishable at room temperature; however, broadening
Cyclic voltammetry: The electrochemical data of 1a–1 f, 2a–
2 f, 3c, 4b, 4c, 5b, and 5d are summarized in Table 1. The
cyclic voltammograms of 1d and 2d are depicted in
Chem. Eur. J. 2007, 13, 417 – 435
ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
419

C.-M. Che et al.
Table 1. Thermogravimetric and electrochemical data[a] of 1a–1 f, 2a–2 f,
3c, 4b, 4c, 5b and 5d.
Figure 2. Complexes 1a–1 f, 3c, 4b, and 4c show one rever-
1
sible reduction couple (E = =À1.52 to À1.86 V versus
2
[b]
[Cp2Fe]+/0) in DMF solution at 298 K; this couple presuma-
1
Complex Td
Reduction E =
Quasi-reversible Anodic peak Epa
2
[8C] [V][c]
couple[c]
[V][c]
bly corresponds to reduction of the (RC^N^N) ligand. The
1a
1b
1c
1d
1e
1 f
2a
2b
2c
2d
2e
2 f
3c
4b
4c
5b
5d
470
484
509
532
479
549
385
378
376
380
379
381
376
320
349
421
337
À1.76
–
–
–
–
–
–
0.44
0.54
0.45
0.58
0.37
0.56
–
–
–
–
–
–
–
–
–
0.53
0.63
1
E = of this reduction couple for 1b occurs at À1.86 V, while
2
À1.86
it is anodically shifted to À1.66 V for 1 f due to the electron-
À1.73
withdrawing 3,5-(CF3)Ph substituent on the (RC^N^N)
À1.73
ligand. Complexes 1a–1 f show an irreversible oxidation
À1.70
wave in the range Epa =0.37–0.58 V versus Cp2Fe+/0
.
À1.66
À1.48
À1.67
The dinuclear complexes 2a–2d show two reduction cou-
À1.52
À1.75
1
ples in the ranges E = =À1.43 to À1.52 (reversible) and
2
À1.43
À1.69
À1.67 to À1.75 V (quasi-reversible), respectively, versus
À1.51
À1.69
À1.32, À1.53
À1.28, À1.48
À1.52
–
–
–
–
–
–
–
[Cp2Fe]+/0. The trinuclear complex 5b shows one reversible
1
reduction couple at E = =À1.68 V, whereas 5d shows two re-
2
1
versible couples at E = =À1.44 and À1.62 V, respectively.
2
À1.60
These reduction couples are presumably ligand-centered.
À1.55
The observation of two reversible reduction couples for the
dinuclear and trinuclear PtII complexes, whereas only one
ligand-centered reduction couple is observed for its mono-
nuclear congeners, suggests coupling between the
[(RC^N^N)Pt] units upon reduction.[13,16,20]
À1.68
À1.44, À1.62
[a] Determined in DMF at 298 K with 0.1m nBu4NPF6 as the supporting
electrolyte; scan rate=50 mVsÀ1
.
[b] Decomposition temperature.
[c] Value versus E = (Cp2Fe+/0) (0.11–0.13 V versus Ag/AgNO3 (0.1m in
1
2
MeCN) reference electrode).
Crystal structures: X-ray crystal data[30] as well as selected
bond distances and angles for 1a, 1c, 2a–2d, 2 f, 3c, 4b, 4c,
and 5b are listed in Table 2 and Table 3, respectively. Per-
spective views are depicted in the figures below. The coordi-
nation geometries of 1a, 1c, 3c, 4b, and 4c (Figure 3) are
similar to that of the 6-phenyl-2,2’-bipyridyl congener
[(C^N^N)PtCl]. In each case, the Pt atom adopts a distort-
ed square-planar geometry, as revealed by the N(1)-Pt(1)-
C(1) angle of 163.1(3)8 in 1a, the N(1)-Pt(1)-C(16) angle of
163.1(8)8 in 1c, the N(1)-Pt(1)-C(1) angle of 158.4(5)8 in 3c,
the N(2)-Pt(1)-C(16) angle of 156.3(2)8 in 4b and the N(2)-
Pt(1)-C(1) angle of 156.6(2)8 in 4c; these angles deviate sig-
nificantly from 1808. The coordinating O, N, Pt and Cl
atoms in 1a and 1c are close to co-planar, with the Cl atom
lying out of the plane by only 3.68 and 2.28, respectively. On
the other hand, the PPh3 or PCy3 groups of 3c, 4b and 4c
lie out of the plane by 7.08, 19.68 and 14.18, respectively. We
suggest that intermolecular p···p interactions between neigh-
boring [(RC^N^N)Pt
(PR3)]+ molecules would be enhanced
A
by bending of the phosphine ligand out of the PtII coordina-
tion plane such that the (RC^N^N) planes are in proximity.
À
The Pt N distances in 1a, 1c, 3c, 4b and 4c are 1.9–2.2 Š
(Table 3); these values are comparable to those in
[(C^N^N)Pt(PPh3)]ClO4 ((C^N^N)=6-phenyl-2,2’-bipyrid-
G
yl; Pt N=1.985 and 2.12 Š),[20] [(O^N^N)PtCl]·CH2Cl2
((O^N^N)=6-(2-hydroxyphenyl)-2,2’-bipyridyl; 2.00 Š),[31]
[(tBuO^N^N)PtCl] ((tBuO^N^N)=4,4’-di-tert-butyl-6-(2-
hydroxyphenyl)-2,2’-bipyridyl; 1.979 and 2.006 Š)[32] and [Pt-
À
A
N
throline; 1.960 and 1.978 Š).[33] The Pt Cl distances in 1a
(2.3136 Š) and 1c (2.314 Š) resemble those of
[(O^N^N)PtCl] and [(tBuO^N^N)PtCl] (2.3 Š).[31,32] For
À
À
3c, 4b, and 4c, the Pt P (2.253, 2.2826 and 2.2971 Š, respec-
Figure 2. Cyclic voltammograms of 1d (top, 10À4 m) and 2d (bottom,
10À4 m) in DMF containing 0.1m nBuNPF6 as supporting electrolyte at
À
tively) and Pt C distances (2.001, 2.054 and 2.041 Š, respec-
298 K. Scan rate: 50 mVsÀ1
.
tively) are similar to those in [(C^N^N)Pt
A
À
420
www.chemeurj.org
ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2007, 13, 417 – 435

Platinum(II) Complexes with Cyclometalated Ligands
FULL PAPER
Table 2. Crystal data of 1a, 1c, 2a–2d, 2 f, 3c, 4b, 4c, and 5b.
Complex
formula
1a
1c
3c
4b
4c
C24H15ClN2Pt·CHCl3
C30H19ClN2Pt·2.5CHCl3
C48H33ClN2O4PPt·CH3OH
C46H56ClN2O4PPt·2CH3CN
C48H52ClN2O4-
PPt·0.5CH3CN
1002.95
yellow
0.4”0.35”0.2
monoclinic
C2/c
26.188(5)
14.708(3)
24.052(5)
90
99.88(3)
90
FW
color
681.29
yellow
0.6”0.15”0.1
monoclinic
P21/n
7.926(2)
19.361(4)
15.290(3)
90
100.28(3)
90
2308.7(8)
4
936.43
yellow
995.32
yellow
1044.55
yellow
0.3”0.2”0.2
monoclinic
P21/n
16.423(3)
17.976(4)
17.270(4)
90
110.42(3)
90
4778.1(18)
4
crystal size [mm3]
crystal system
space group
a [Š]
0.50”0.10”0.06
triclinic
0.35”0.15”0.06
triclinic
¯
¯
P1 (no. 2)
P1 (no. 2)
10.306(2)
14.437(3)
24.212(5)
98.21(3)
100.58(3)
96.48(3)
3468.9(12)
4
1.793
4.726
1812
47.4
10.713(2)
13.300(3)
16.081(3)
71.77(3)
75.45(3)
77.53(3)
2082.8(7)
2
1.587
3.522
990
45.00
b [Š]
c [Š]
a [8]
b [8]
g [8]
V [Š3]
Z
9127(3)
8
1.460
3.214
4056
1calcd [gcmÀ3
]
1.960
6.558
1304
50.98
1.452
3.073
2128
51.24
m [mmÀ1
(000)
2qmax [8]
]
F
A
50.68
no. unique data
Gof [F2]
R[a]
4003
1.06
0.040
0.102
5398
0.89
0.061
0.11
2839
0.730
0.049
0.103
8321
0.833
0.035
0.072
7091
0.92
0.031
0.076
[b]
Rw
À3
residual 1 [eŠ
]
1.389, À1.314
1.276, À0.970
0.808, À0.597
0.851, À1.458
0.594, À0.602
CCDC number
601687
287984
287987
287985
287988
Complex
formula
2a
2b
2c
2d
2 f
5b
C73H52Cl2N4O8-
P2Pt2·0.5CH3CN·H2O
1674.75
yellow
0.30”0.20”0.15
monoclinic
P21/c
23.309(5)
14.645(3)
19.144(4)
90
94.91(3)
90
C81H68Cl2N4O8-
P2Pt2·2CH3CN
1830.52
yellow
0.35”0.30”0.25
monoclinic
C2/c
13.315(3)
27.131(5)
21.041(4)
90
98.47(3)
90
7518(3)
4
1.617
3.893
C85H60Cl2N4O8-
P2Pt2·3CH3CN
1910.54
C
101H92Cl2N4O8-
C89H56Cl2F12N4O8-
P2Pt2·6CH2Cl2
2569.95
orange
0.40”0.15”0.12
monoclinic
C2/c
22.067(4)
25.992(5)
18.102(4)
90
100.99(3)
90
C116H98Cl3N6O12-
P3Pt3·2CH3CN
2634.64
yellow
0.35”0.3”0.2
orthorhombic
P212121
14.402(3)
19.809(4)
38.566(8)
90
90
90
11002(4)
4
1.591
P2Pt2·2CH2Cl2·C4H10O
2256.78
orange
0.50”0.25”0.10
monoclinic
P21/n
15.672(3)
34.206(7)
19.870(4)
90
106.16(3)
90
10231(4)
4
1.465
2.977
FW
color
yellow
crystal size [mm3]
crystal system
space group
a [Š]
0.35”0.20”0.10
triclinic
¯
P1 (no. 2)
12.435(3)
15.434(3)
22.325(5)
108.25(3)
93.07(3)
105.80(3)
3869.9(15)
2
1.640
3.786
1894
50.98
b [Š]
c [Š]
a [8]
b [8]
g [8]
V [Š3]
6511(2)
4
1.708
4.487
3292
10192(4)
4
1.675
3.218
5048
Z
1calcd [gcmÀ3
]
m [mmÀ1
(000)
2qmax [8]
]
3.987
5224
48.80
F
A
3640
50.90
4544
51.10
50.64
50.68
no. unique data
Gof [F2]
R[a]
7641
0.87
0.049
0.11
6490
1.08
0.037
0.044
1.164, À1.653
287992
2
12856
0.93
0.042
0.062
12371
0.81
0.050
0.114
8066
0.93
0.046
0.072
14453
0.596
0.037
0.082
[b]
Rw
À3
residual 1 [eŠ
]
1.083, À1.221
1.222, À0.861
1.073, À1.041
0.839, À1.057
0.664, À0.614
CCDC number
287990
287986
287991
287987
601688
[a] R=ꢀjjFo jÀjFc jj/ꢀjFo j. [b] Rw =[ꢀw(jFojÀjFcj)2/ꢀwjFo j ]1/2
.
[20]
À
P=2.243, Pt C=2.00 Š). In the crystal structures of 1a,
1c, 3c, 4b and 4c, the molecules are oriented in pairs anti to
each other, with an intermolecular p···p stacking distance of
about 3.5 Š and Pt···Pt distances greater than 4 Š.
2.3 and 2.0–2.1 Š, respectively; Table 3) in these complexes
À
are similar to those in [(C^N^N)2Pt2
T
G
[20]
À
N=1.985 and 2.12, Pt P=2.248 and Pt C=2.024 Š). The
intramolecular Pt···Pt distance of 3.165(1) Š in 2a is slightly
Complexes 2a–2d and 2 f consist of two (RC^N^N)Pt
units bridged by a dppm ligand (Figure 4), while the three
(RC^N^N)Pt moieties in 5b are bridged by a dpmp ligand
shorter than those in [(C^N^N)2Pt2
(3.270),[13,16,18,20]
[(C^N^N)2Pt2(m-dppm)]
(3.245),[13,16,18,20] [(C^N^N)3Pt3
(m-dpmp)](ClO4)3·H2O (3.190
and 3.399), [(C^N^N)3Pt3(m-dpmp)]
A
(ClO4)2
E
ACHTREUNG
A
ACHTREUNG
À
À
À
(Figure 5). The Pt N, Pt P and Pt C distances (2.0–2.2, 2.2–
A
ACHTREUNG
Chem. Eur. J. 2007, 13, 417 – 435
ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org

C.-M. Che et al.
Table 3. Selected bond lengths [Š] and angles [8] for 1a, 1c, 2a–2d, 2 f, 3c, 4b, 4c, and 5b.
1a
À
À
À
À
Pt(1) C(1)
N(2)-Pt(1)-C(1)
2.088(5) Pt(1) N(1)
80.1(2) N(2)-Pt(1)-N(1)
1.997(8) Pt(1) N(2)
1.958(5) Pt(1) Cl(1)
163.1(3) N(2)-Pt(1)-Cl(1)
2.314(2)
176.4(2) C(1)-Pt(1)-Cl(1)
83.0(3)
N(1)-Pt(1)-C(1)
96.9(2)
97.4(5)
N(1)-Pt(1)-Cl(1) 99.9(2)
1c
1.94(2)
À
À
À
À
Pt(1) C(16)
2.08(2)
Pt(1) N(1)
2.12(2)
82.2(8)
Pt(1) N(2)
Pt(1) Cl(1)
2.314(6)
177.8(5) Cl(1)-Pt(1)-C(16)
C(16)-Pt(1)-N(2) 80.9(7)
Cl(1)-Pt(1)-N(1) 99.5(6)
N(1)-Pt(1)-N(2)
N(1)-Pt(1)-C(16) 163.1(8) N(2)-Pt(1)-Cl(1)
2a
À
À
À
À
À
Pt(1) C(1)
2.04(1)
2.16 (1) Pt(2) N(4)
81.6(5)
77.8(5)
Pt(1) N(1)
2.12(1)
2.04(1)
77.4(5)
Pt(1) N(2)
2.00(1)
2.252(4) Pt(1)···Pt(2)
94.8(5) N(1)-Pt(1)-P(1)
103.4(4) Pt(1)-P(1)-P(2)-Pt(2) 16.3(1)
2b
2.024(4) Pt(1) P(1)
Pt(1) P(1)
2.245(4) Pt(2) C(25)
3.165(1)
2.02(2)
82.7(5)
À
À
À
Pt(2) N(3)
Pt(2) P(2)
C(1)-Pt(1)-N(2)
N(3)-Pt(2)-N(4)
N(1)-Pt(1)-N(2)
C(25)-Pt(2)-P(2) 96.1(4)
C(1)-Pt(1)-P(1)
N(3)-Pt(2)-P(2)
105.9(3) C(25)-Pt(2)-N(4)
À
À
À
À
Pt(1) C(16)
2.007(5) Pt(1) N(1)
2.158(4) Pt(1) N(2)
2.248(1) Pt(1)···Pt(1*)
105.7(2) Pt(1)-P(1)-P(1*)-Pt(1*) 29.69(5)
3.198(7)
C(16)-Pt(1)-N(2) 81.8(2)
N(1)-Pt(1)-N(2)
77.9(2)
C(16)-Pt(1)-P(1) 94.5(2)
N(1)-Pt(1)-P(1)
2c
À
À
À
À
À
À
Pt(1) C(16)
2.010(8) Pt(1) N(1)
2.166(6) Pt(2) N(4)
2.150(6) Pt(1) N(2)
2.017(6) Pt(1) P(1)
2.243(2) Pt(2) C(46)
3.37(4)
2.032(7)
80.5(3)
À
À
Pt(2) N(3)
2.049(6) Pt(2) P(2)
2.261(2) Pt(1)···Pt(2)
N(1)-Pt(1)-P(1)
C(16)-Pt(1)-N(2) 81.8(3)
N(1)-Pt(1)-N(2)
77.7(2)
C(16)-Pt(1)-P(1) 94.6(2)
105.7(2) C(46)-Pt(2)-N(4)
N(3)-Pt(2)-N(4)
77.5(2)
C(46)-Pt(2)-P(2) 96.5(2)
N(3)-Pt(2)-P(2)
105.4(2) Pt(1)-P(1)-P(2)-Pt(2) 1.82(8)
2d
À
À
À
À
À
À
Pt(1) C(1)
2.05(1)
2.15(1)
82.2(4)
77.9(4)
Pt(1) N(1)
2.167(9) Pt(1) N(2)
2.027(9) Pt(2) P(2)
2.015(9) Pt(1) P(1)
2.247(3) Pt(1)···Pt(2)
93.7(3)
2.261(3) Pt(2) C(39)
3.29(6)
2.00(1)
81.7(4)
À
À
Pt(2) N(3)
Pt(2) N(4)
C(1)-Pt(1)-N(2)
N(3)-Pt(2)-N(4)
N(1)-Pt(1)-N(2)
C(39)-Pt(2)-P(2) 95.9(3)
77.2(4)
C(1)-Pt(1)-P(1)
N(3)-Pt(2)-P(2)
N(1)-Pt(1)-P(1)
107.0(3) C(39)-Pt(2)-N(4)
104.5(2) Pt(1)-P(1)-P(2)-Pt(2) 0.2(1)
2 f
2.152(6) Pt(1) P(1)
94.9(2) N(2)-Pt(1)-P(1)
3c
À
À
À
À
Pt(1) C(1)
2.031(8) Pt(1) N(1)
2.034(6) Pt(1) N(2)
2.255(2) Pt(1)···Pt(2)
106.0(2) Pt(1)-P(1)-P(1*)-Pt(2*) 0.20(7)
3.28(4)
C(1)-Pt(1)-N(1)
81.8(3)
N(1)-Pt(1)-N(2)
77.2(2)
C(1)-Pt(1)-P(1)
À
À
À
À
Pt(1) C(1)
N(2)-Pt(1)-N(1)
2.00(2)
77.8(4)
Pt(1) N(1)
N(2)-Pt(1)-C(1)
2.13(1)
81.1(5)
Pt(1) N(2)
N(2)-Pt(1)-P(2)
1.976(6) Pt(1) P(2)
173.1(3) C(1)-Pt(1)-P(2)
2.253(4) C(1)-Pt(1)-N(2)
96.4(5)
105.1(3)
96.4(5)
N(1)-Pt(1)-P(2)
4b
2.103(4) Pt(1) P(1)
C(16)-Pt(1)-P(1) 102.4(2) N(2)-Pt(1)-P(1)
À
À
À
À
Pt(1) C(16)
C(16)-Pt(1)-N(2) 156.3(2) N(1)-Pt(1)-N(2)
2.054(5) Pt(1) N(1)
2.023(4) Pt(1) N(2)
78.6(2)
2.283(2)
101.2(1) N(1)-Pt(1)-C(16)
79.6(2)
80.5(2)
N(1)-Pt(1)-P(1)
160.7(1)
4c
À
À
À
À
Pt(1) C(1)
2.041(6) Pt(1) N(1)
156.6(2) N(1)-Pt(1)-N(2)
165.9(1)
2.028(4) Pt(1) N(2)
77.8(2) C(1)-Pt(1)-P(1)
2.154(5) Pt(1) P(1)
99.9(1) N(2)-Pt(1)-P(1)
2.297(1)
103.3(1) N(1)-Pt(1)-C(1)
C(1)-Pt(1)-N(2)
N(1)-Pt(1)-P(1)
5b
À
À
À
À
À
Pt(1) C(1)
2.01(1)
2.06(1)
Pt(1) N(1)
2.157(9) Pt(1) N(2)
2.019(9) Pt(1) P(1)
2.263(3) Pt(3) N(6)
2.255(3) Pt(2) N(4)
2.024(8)
2.05(1)
À
À
À
À
À
Pt(2) C(29)
Pt(2) N(3)
2.172(8) Pt(2) P(2)
2.035(8) Pt(3) C(57)
À
À
Pt(3) N(5)
2.163(9) Pt(3) P(3)
2.260(3)
C(1)-Pt(1)-N(2)
N(1)-Pt(1)-P(1)
81.0(4)
C(1)-Pt(1)-N(1)
159.1(4) N(2)-Pt(1)-N(1)
78.2(3)
76.0(3)
C(1)-Pt(1)-P(1)
C(29)-Pt(2)-N(3)
N(6)-Pt(3)-N(5)
100.0(3) N(2)-Pt(1)-P(1)
157.2(3) N(4)-Pt(2)-P(2)
173.2(3)
174.3(3)
158.5(3)
100.9(2) N(4)-Pt(2)-C(29) 81.5(4)
N(3)-Pt(2)-P(2)
175.6(3) C(57)-Pt(3)-P(3) 98.4(3)
N(4)-Pt(2)-N(3)
C(29)-Pt(2)-P(2) 95.0(3)
N(6)-Pt(3)-P(3)
107.7(2) N(6)-Pt(3)-C(57) 80.5(4)
N(5)-Pt(3)-P(3) 103.1(2)
77.9(3)
C(57)-Pt(3)-N(5)
(3.364
and
3.617),
(3.217
(m-dpmp)]
3.647 Š).[16] In the dinuclear complexes, the intramolecular
Pt···Pt contacts are in the order: 2a (3.16(1)) 2b
[(tBuC^N^N)3Pt3
and 3.601)
(ClO4)3·2Et2O (3.466 and
G
1638 are indicative of the presence of weak d8···d8 and
ligand–ligand interactions across Pt1···Pt2···Pt3. These values
are similar to those in the trinuclear substituted (C^N^N)
ACHTREUNG
N
ACHTREUNG
analogues
3.62 Š,
[(C^N^N)3Pt3
1628),
N
R
(3.36,
<
ACHTREUNG
(3.198(7)) < 2 f (3.28(4)) < 2d (3.29(6)) < 2c (3.37(4) Š).
These values fall in the range of intermetal separations nor-
mally observed for platinum(II) complexes containing an ex-
tended linear chain structure (3.09–3.50 Š). There is no
close intermolecular Pt···Pt contact between adjacent
C
and
(3.47,
G
[(RC^N^N)2Pt2
(m-dppm)]2+ molecules. In the trinuclear
A
complex 5b, the intramolecular Pt1···Pt2 contact of 3.53 Š,
Pt2···Pt3 contact of 3.30 Š and the Pt1···Pt2···Pt3 angle of
422
www.chemeurj.org
ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2007, 13, 417 – 435

Platinum(II) Complexes with Cyclometalated Ligands
FULL PAPER
Figure 3. Molecular structures of a) 1a, b) 1c (torsion angle a(C11-C12-C25-C26)=318), c) 3c (a(C12-C13-C25-C26)=428), d) 4b, and e) 4c (a(C12-
C13-C25-C26)=288). The thermal ellipsoids are at 30% probability. All hydrogen atoms and solvent molecules have been omitted for clarity. The insets
show the out-of-plane angle of Cl, PPh3, or PCy3.
tion in p-stacking aromatic moieties due to electrostatic re-
pulsion.[35] Eclipsed p-stacking of aromatic moieties shows
an increased stability when the aromatic moieties bear an
electronegative atom such as nitrogen. In the literature, an
eclipsed alignment in metal complexes containing multiden-
tate N-donor ligands remains sparse.[34] In this work, the two
(RC^N^N) planes in 2a or 2b adopt a staggered configura-
tion such that a small deviation from co-planarity is ob-
throline)copper(I)–acetone solvate (ca. 3.7 Š)[37]) that are
displaced in parallel at an angle of 16–408.[35] The a(Pt-P-P-
Pt) torsion angles, between the two staggered (RC^N^N)Pt
moieties in 2a and 2b are 16.3(1)8 and 29.69(5)8, respective-
ly. These torsion angles are significantly smaller than that of
44.68 in the 6-phenyl-2,2’-bipyridyl congener [(C^N^N)2Pt2-
[13,16,18,20]
A
.
On the other hand, 2c, 2d and 2 f ex-
hibit an almost eclipsed alignment of the two
[(RC^N^N)Pt] planes, with estimated interplane distances
of about 3.3–3.4 Š. The a(Pt-P-P-Pt) angles of 2c, 2d and
2 f are 1.82(8)8, 0.19(13)8 and 0.20(7)8 respectively; these
angles are close to zero even though the complexes bear
bulky R groups on the ligand (Ph in 2c, 3,5-tBu2Ph in 2d
and 3,5-(CF3)2Ph in 2 f). Thus, the two (RC^N^N)Pt units
served. The interplanar distances of the Pt(RC^N^N) moi-
A
eties, as estimated by the Pt···Pt separations of around
3.2 Š, are slightly shorter than those (3.4–4.6 Š) reported
for most transition-metal pyridine or quinoline moieties[35]
(such as (2,2’-bipyridyl-N,N’)dicyanoplatinum(II) and -palla-
dium(II) (ca. 3.4 Š)[36] and 3,4,7,8-tetramethyl-1,10-phenan-
Chem. Eur. J. 2007, 13, 417 – 435
ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
423

C.-M. Che et al.
Figure 4. Molecular structures of a) 2a, b) 2b, c) 2c (torsion angle a(C11-C12-C25-C26)=218), d) 2d (a(C12-C13-C25-C26)=318), and e) 2 f (a(C12-
C13-C25-C26)=278). The thermal ellipsoids are at 30% probability. All hydrogen atoms and solvent molecules have been omitted for clarity.
of these dinuclear PtII complexes are nearly parallel to each
other and are related by a C2 axis passing through the CH2
moiety of the dppm ligand. We have observed previously
that when the extent of p-conjugation in the cyclometalated
ligand of dinuclear complexes (2c, 2d and 2 f, where R in-
volves a phenyl group) is increased, the extent of slipping or
offset between the ligand planes is decreased (i.e. the prefer-
ence for an eclipsed configuration is increased).
The three (RC^N^N)Pt units in 5b are partially stag-
gered, with a(Pt2-P-P-Pt3) and a(Pt1-P-P-Pt2) torsion
424
www.chemeurj.org
ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2007, 13, 417 – 435

Platinum(II) Complexes with Cyclometalated Ligands
FULL PAPER
longer parallel as in the dinuclear analogue 2b, presumably
due to the bulkiness of the tert-butyl group on the
(RC^N^N) ligand.
In previous work on the [(C^N^N)PtX] system,[13,16,18,20]
shorter Pt···Pt distances are accompanied by a larger torsion
angle between the two (C^N^N)Pt moieties. This was attrib-
uted to a repulsive effect between the (C^N^N) ligands in a
staggered rather than an eclipsed conformation.[35] In this
work, the extended p-conjugation in (RC^N^N) leads to in-
creased intramolecular metal–metal and ligand–ligand inter-
actions in the dinuclear [(RC^N^N)2Pt2
N
N
complexes. Such intramolecular interactions restrict the mo-
lecular motion of the flexible Pt-P-CH2-P-Pt moiety and
could be the reason for the enhancement of the correspond-
ing emission intensity in solution, as discussed in the follow-
ing section.
Absorption and emission spectroscopy of the mononuclear
complexes: The spectroscopic and photophysical data of 1a–
1 f, 3c, 4b, 4c, 5b and 5d are listed in Table 5. The absorp-
tion spectra of 1a–1 f, 3c, 4b and 4c reveal several intense
transitions at lmax values ranging from 250–390 nm. These
were assigned to be mainly due to intraligand transitions
since similar absorptions are found in the free (RC^N^NH)
ligand.
The broad absorption at 400–470 nm (eꢀ6800–
10000 cmÀ1 molÀ1 dm3) for 1a–1 f could be attributed to a
1MLCT (5d)Pt!p*(L) transition, although mixing with IL
could not be excluded. The absorption tail at around 500 nm
is
tentatively
assigned
to
a
3MLCT
transi-
tion.[11,13,16,18,20,36,38,39] The absorption spectra of 1d in CH2Cl2
and DMF solution are depicted in Figure 6 as an example.
The absorption band at around 450 nm exhibits only a small
solvatochromic shift (8 nm) on
Figure 5. Molecular structure of 5b. The thermal ellipsoids are at 30%
probability. All hydrogen atoms and solvent molecules have been omit-
ted for clarity. Top: View from the top; bottom: view from the side.
Table 4. Selected structural parameters regarding Pt···Pt interactions in dinuclear PtII complexes.
changing from CH2Cl2 to
DMF.
Complex
Pt···Pt distance
[Š]
Torsion angle
Pt1···Pt2···Pt3
angle [8]
Complexes
1a–1 f
[8]
[(RC^N^N)PtCl] are strongly
emissive, with lmax that depend
on the substituent group R.
The emission energy in solu-
tion follows the order: R=3,5-
(tBu)2Ph (1d, lmax =533 nm) >
phenyl (1c, 537) in CH2Cl2 (2”
10À5 m), and 3,5-F2Ph (1e, 614)
A
U
3.270
3.245
3.150
3.165
3.198
3.374
3.294
3.276
44.6
20.7
27.2
16.3
29.7
1.8
0.2
0.2
–
–
–
–
–
–
–
–
163
162
157
162
G
U
C
A
2a[b]
2b[b]
2c[b]
2d[b]
2 f[b]
5b
3.300, 3.533
3.194, 3.399; 3.364, 3.617
3.217, 3.601
3.466, 3.647
8.9, 29.3
15.5, 26.3; 4.7, 34.6
9.3, 29.6
G
>
3,5-(CF3)2Ph (1 f, 618) in
U
ACHTREUNG
DMF (2”10À5 m).
A
similar
N
8.9, 33.7
trend has also been observed
for the emission of the
[a] See references [13], [16], [18], and [20]. [b] In syn-form.
[(RC^N^N)Pt
A
plexes 4b and 4c in MeCN
angles of 29.38 and 8.98, respectively, and estimated inter-
plane distances of about 3.3–3.5 Š; these structural data re-
semble those in the trinuclear (C^N^N) analogues (5–358
and 3.2–3.7 Š).[16] The Pt···Pt distances and torsion angles
for the dinuclear and trinuclear complexes are listed in
Table 4. The displaced (RC^N^N)Pt planes in 5b are no
(8”10À5 m): R=phenyl (4c, 621 nm) < tBu (4b, 603). The
emission spectra recorded for 1e and 1 f in DMF solution
are not vibronically resolved. We assigned the emission of
1a–1 f, 3b, 4b and 4c at 525–618 nm (CH2Cl2, MeCN or
DMF solution) to a triplet excited state with 3IL and
3MLCT parentage. There is a lack of dependence of the
Chem. Eur. J. 2007, 13, 417 – 435
ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
425

C.-M. Che et al.
Table 5. Spectroscopic and photophysical data for 1a–1 f, 3c, 4b, and 4c.
[d]
Medium
(T [K])
labs [nm][a,b]
lem [nm][c] (t [ms]);
Fem
[e]
(e [”104 cmÀ1 molÀ1 dm3])
kq [109 sÀ1dmÀ1 molÀ1
]
1a CH2Cl2 (298)
249 (6.29), 289 (3.84), 307 (4.36), 343 (3.37), 381 (1.12), 416 (0.48), 451
(0.18), 500 (~0.01)
–
–
529 (6), 566, 595[f]; 6.8
0.20
–
–
–
solid (298)
solid (77)
2-MeTHF (77)
1b CH2Cl2 (298)
588 (6), 635 (6), 694 (6)
588 (14), 639 (14), 699 (14)
521 (88), 563 (88), 609 (88)[b]
–
250 (5.01), 290 (3.54), 305 (3.46), 342 (2.68), 375 (0.92), 408 (0.44), 450
525 (6), 566, 591 (6), 633, 703[f]; 0.8 0.29
(0.11), 500 (~0.01)
solid (298)
solid (77)
2-MeTHF (77)
–
–
–
609 (1), 693 (1)
–
–
–
578 (13), 593 (13), 626 (13)
518 (97), 567 (97), 576 (32), 624
(32)[b]
1c CH2Cl2 (298)
260 (6.40), 313 (4.69), 344 (3.04), 387 (0.99), 417 (0.60), 454 (0.10), 500
537 (7), 570[f]; 9.0
0.42
(~0.02)
–
–
–
solid (298)
solid (77)
2-MeTHF (77)
1d CH2Cl2 (298)
615 (5)
–
–
–
0.68
603 (9), 654 (9)
525 (43), 567 (43), 614 (43)[b]
533 (7), 569[f]; 1.6
254 (6.43), 314 (5.05), 344 (3.30), 386 (1.07), 415 (0.68), 458 (0.12), 500
(~0.01)
DMF (298)
solid (298)
351 (4.84), 324 (4.89), 386 (1.22), 416 (0.78), 450 (0.22)
–
601 (11)[f]; 0.5
613 (2), 659 (2)
0.02
–
solid (77)
–
–
610 (11), 659 (11), 720 (11)
523 (52), 566 (52), 617 (52)[b]
614 (0.7)[f]; 1.2
615 (3), 661 (3), 725 (3)
615 (10), 668 (10), 728 (10)
532 (33), 575 (33), 619 (33)[b]
618 (0.7)[f]; 0.9
–
–
0.03
–
–
–
0.02
–
–
2-MeTHF (77)
1e DMF (298)
solid (298)
315 (4.19), 343 (2.88), 395 (1.09), 422 (0.64), 465 (0.11), 500 (~0.01)
–
–
–
solid (77)
2-MeTHF (77)
1 f DMF (298)
solid (298)
316 (4.41), 344 (3.03), 395 (1.19), 427 (0.61), 467 (0.10), 500 (~0.04)
–
–
–
626 (2)
618 (12), 669 (12)
solid (77)
DMF/MeOH/EtOH
(1:1:4) (77)
537 (35), 596 (35), 650 (35), 715
–
(35)[b]
3c MeCN (298)
solid (298)
196 (13.2), 247 (6.8), 310 (5.8), 388 (1.4), 500 (~0.05)
520 (8), 560 (8), 612 (8)[b]; 2.1
599 (15), 650 (15), 707 (15)
595 (35), 651 (35), 713 (35)
516 (830), 558 (830), 605 (830)
0.02
–
–
–
–
–
–
solid (77)
DMF/MeOH/EtOH
(1:1:4) (77)
4b MeCN (298)
solid (298)
242 (5.4), 281 (4.0), 315 (4.0), 378 (1.2), 500 (~0.03)
603 (3)[b]; 2.5
611 (11)
603 (43), 640 (43), 702 (43)
515 (880), 555 (880), 606 (880)
0.08
–
–
–
–
–
–
solid (77)
DMF/MeOH/EtOH
(1:1:4) (77)
4c MeCN (298)
solid (298)
250 (6.9), 313 (5.3), 389 (1.3), 500 (~0.01)
521, 561, 611 (3.0)[b]; 2.2
633 (17)
620 (74), 673 (74)
0.003
–
–
–
–
–
–
solid (77)
DMF/MeOH/EtOH
(1:1:4) (77)
521 (540), 564 (540), 611 (540)
[a] Absorption maxima. [b] At 4”10À5 m. [c] Emission maxima. [d] Emission quantum yield. [e] Emission self-quenching constant. [f] At 2”10À5 m.
emission energies on the complex concentrations from 10À4
to 10À6 m, which suggests that these emissions are not exci-
meric 3p–p* or 3MMLCT in nature; these emissions are
probably IL charge-transfer in nature. The emission of 1d
is affected by the solvent: its lmax red-shifts from 533 nm in
CH2Cl2 to 601 nm in DMF solution (Figure 6).
state by (a) non-radiative process(es). The emission quan-
tum yields of 1e and 1 f in DMF are 0.02–0.03, lower than
that of 1a–1d in CH2Cl2 solution, probably due to the
quenching effect of DMF. When the auxiliary Cl ligand is
replaced with PPh3 or PCy3, as in 3c, 4b and 4c, the quan-
tum yield (0.003–0.08) decreases significantly.
3
The emission quantum yields of 1a–1d in CH2Cl2 solution
range from 0.20 to 0.68, which are significantly higher than
that of the congeners [(C^N^N)PtCl] ((C^N^N)=6-phenyl-
2,2’-bipyridyl and derivatives; Fꢀ0.03–0.07).[13,20] It is likely
that the extended p-conjugated (RC^N^N) ligands have a
rigid structure, which disfavors deactivation of the excited
In the solid state at room temperature, 1a–1 f, 3b, 4b and
4c show a vibronic structured emission with lmax at 588–
633 nm. Upon cooling to 77 K, the emission is slightly blue-
shifted. These emissions are assigned to 3MLCT excited
states. Glassy solutions (2-MeTHF or DMF/MeOH/EtOH,
1:1:4, 4”10À5 m) of 1a–1 f, 3b, 4b and 4c were found to ex-
426
www.chemeurj.org
ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2007, 13, 417 – 435

Platinum(II) Complexes with Cyclometalated Ligands
FULL PAPER
assigned to excited states with mixed MMLCT
U
has previously been reported in [Pt
C
G
pz)]3+ (pz=pyrazole)[17,39] and the 6-phenyl-2,2’-bipyridyl
[13,16,18,20]
congener [(C^N^N)2Pt2
(m-dppm)]2+
.
All of the ab-
sorption bands described above obey Beerꢁs Law in the con-
centration range 10À3 to 10À6 m, thereby suggesting that
there is no dimerization or oligomerization of the metal
complexes in the ground state. Complex 2d shows similar
absorption profiles in MeCN, CH2Cl2, MeOH and DMF at
room temperature; for example, the absorption band at
about 470 nm exhibits only a small solvatochromic shift
(ꢁ5 nm) upon changing the solvent from MeCN to CH2Cl2,
MeOH and DMF (Figure 7). The absorption band of 5d at
about 500 nm in MeCN, CH2Cl2, MeOH and DMF at room
temperature exhibits a similarly small solvatochromic shift
(ꢁ5 nm; Figure 8).
Complexes 2a–2 f exhibit a peak maxima at 585–638 nm
(F=0.07–0.35) in acetonitrile at room temperature. The
emission energy is affected by the substituent R on the
(RC^N^N) ligand, and follows the order tBu (2b, lmax
=
585 nm) > H (2a, 605) > 3,5-tBu2Ph (2d, 609) > phenyl
(2c, 614) > 3,5-F2Ph (2e, 637) ~3,5-(CF3)2Ph (2 f, 638).
Complexes 5b and 5d are strongly emissive in acetonitrile,
with lmax at 626 (F=0.33) and 608 nm (F=0.19), respec-
tively. In conjunction with the observed intramolecular
Pt···Pt contacts in the crystal structures of 2a, 2c, 2d, 2 f and
5b, the low-energy emission bands of the dinuclear and tri-
nuclear complexes are assigned to a MMLCT
3[ds*!s(p*)]
Figure 6. Absorption (top) and emission (bottom) spectra of 1d in
CH2Cl2 and DMF solution. Inset: expanded spectra in the region of 400
to 550 nm.
3
excited-state and are red-shifted in energy from that of their
mononuclear congeners 1a–1d and 1 f (lmax =529, 525, 537,
533 and 618 nm, respectively). The latter emissions come
from a 3MLCT excited state. At room temperature, the
emissions of 2d in MeCN, CH2Cl2, MeOH and DMF solu-
tion are similar in energy; their lmax undergo only a small
solvatochromic shift (ꢁ6 nm; Figure 7). However, the emis-
sion quantum yield of 2d is strongly affected by the solvent
(F=0.26 in MeCN or CH2Cl2, 0.05 in MeOH and 0.08 in
DMF; Figure 7), presumably due to a quenching effect in
MeOH and DMF. While the emission quantum yield of 5d
is affected by solvent (F=0.19 in MeCN, 0.29 in CH2Cl2,
0.04 in MeOH and <0.01 in DMF), the lmax shows only a
small solvatochromic shift (ꢁ6 nm) when the solvent is
changed from MeCN to CH2Cl2, MeOH and DMF
(Figure 8).
hibit similar vibronically structured emissions, with peak
maxima at 518–537 nm. The spacings are 1300–1400 cmÀ1,
which correspond to the skeletal vibrational frequencies of
the C=C/C=N entities of the (RC^N^N) ligands.[13,16,18,20]
Absorption and emission spectroscopy of the dinuclear and
trinuclear complexes: Spectroscopic and photophysical data
of 2a–2 f, 5b and 5d are listed in Table 6. Dinuclear com-
plexes 2a–2 f show intense absorptions at around 390 nm
(e~2”104 cmÀ1 molÀ1 dm3), with tailing from around 420 to
525 nm (e~0.2”104 cmÀ1 molÀ1 dm3), while the trinuclear
complexes 5b and 5d show intense absorptions band at
around 400 nm (e~2”104 cmÀ1 molÀ1 dm3), with tailing from
around 450 to 550 nm (e~0.25”104 cmÀ1 molÀ1 dm3) in
MeCN. Their mononuclear congeners [(RC^N^N)PtCl]
(1a–1 f) have lower e values in the spectral region around
475 nm. Previous works have shown that metal–metal and
ligand–ligand interactions are present in these dinuclear PtII
complexes, with intramolecular distances of 2.998–
3.432 Š;[13,16–18,20,38,39] such interactions, according to Miskow-
ski and Houlding, destabilize the ds* orbital and stabilize
the lowest unoccupied s*(p) level, resulting in a red-shifted
ds*!s*(p) transition.[8,40] Therefore, the low-energy absorp-
tions at 420–525 nm for the dinuclear complexes and those
at 450–550 nm for the trinuclear complexes are tentatively
Complexes 2a–2 f in the solid state at room temperature
show lmax at 585–636 nm, which are blue-shifted to 569–
613 nm, upon cooling the samples to 77 K. In glassy solution
(DMF/MeOH/EtOH, 1:1:4, 4”10À5 m), the emission is broad
and intense, with lmax ranging from 522 nm for 2d to 605 nm
for 2c. The lack of vibronic structure and the concentration
3
dependence suggest that the emission is unlikely to be IL
3
3
or excimeric p–p*. These emissions are probably MLCT in
nature. Complexes 5b and 5d in the solid state at room tem-
perature show lmax at 623 and 618 nm, respectively, which
blue shift to 603 and 605 nm, respectively, upon cooling the
Chem. Eur. J. 2007, 13, 417 – 435
ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
427

C.-M. Che et al.
Table 6. Spectroscopic and photophysical data for 2a–2 f, 5b, and 5d.
[e]
Medium
(T [K])
labs [nm][a,b]
lem [nm][c,d]
(t [ms])
Fem
(e [”104 cmÀ1 molÀ1 dm3)
2a
2b
2c
2d
MeCN (298)
solid (298)
solid (77)
DMF/MeOH/EtOH (1:1:4) (77)
MeCN (298)
solid (298)
solid (77)
DMF/MeOH/EtOH (1:1:4) (77)
MeCN (298)
solid (298)
solid (77)
DMF/MeOH/EtOH, 1:1:4 (77)
MeCN (298)
CH2Cl2 (298)
MeOH (298)
237 (11.69), 305 (5.59), 392 (1.84), 476 (0.17), 500 (~0.07)
–
–
–
230 (11.69), 308 (5.36), 378 (1.65), 408 (1.50), 450 (0.52), 500 (0.20)
–
–
–
242 (9.80), 306 (7.02), 391 (1.50), 464 (0.19), 500 (~0.08)
–
–
–
240 (11.69), 312 (8.05), 384 (2.14), 466 (0.40), 500 (0.19)
325 (11.0), 383 (3.45), 450 (0.48), 500 (0.19)
205 (14.8), 322 (8.8), 383 (2.5), 450 (0.33)
323 (9.57), 381 (2.74), 415 (1.18), 475 (0.25), 500 (0.14)
605 (1)[f]
636 (6)
0.27
–
–
–
0.35
–
–
–
0.32
–
597 (1)
601 (253)[g]
585 (2)[f]
617 (101)
613 (20), 665 (20)
525 (240), 574 (240)[g]
614 (2)[f]
621 (4)
569 (11), 611 (11), 668 (11)
605 (152)[g]
609 (3)[f]
–
–
0.26
0.26
0.05
0.08
–
606 (3)[f]
618 (13)[f]
DMF (298)
solid (298)
603 (11)[f]
–
585 (13)
solid (77)
DMF/MeOH/EtOH (1:1:4) (77)
MeCN (298)
solid (298)
solid (77)
DMF/MeOH/EtOH (1:1:4) (77)
MeCN (298)
solid (298)
–
–
595 (59)
–
–
0.07
–
–
–
0.09
–
522 (205), 564 (205)[g]
637 (0.2)[f]
600 (4), 635 (4)
597 (7)
2e
2 f
5b
5d
242 (12.41), 294 (8.76), 395 (2.18), 474 (0.51), 500 (0.33), 525 (0.17)
–
–
–
256 (11.59), 302 (7.25), 386 (2.05), 476 (0.17), 500 (~0.08)
–
618 (125)[g]
638 (0.2)[f]
613 (2)
solid (77)
DMF/MeOH/EtOH (1:1:4) (77)
MeCN (298)
solid (298)
solid (77)
DMF/MeOH/EtOH (1:1:4) (77)
MeCN (298)
CH2Cl2 (298)
MeOH (298)
DMF (298)
–
–
609 (3)
598 (103)
–
–
0.33
–
–
237 (15.9), 303 (7.8), 400 (2.4), 475 (0.44), 500 (~0.22)
–
–
–
238 (15.7), 314 (10.5), 400 (2.3), 450 (0.51), 500 (0.34)
238 (18.3), 315 (12.3), 391 (3.1), 410 (2.8), 475 (0.4), 500 (0.25)
205 (18.1); 240 (16.1), 314 (12.1), 404 (2.8), 475 (0.51), 500 (0.26)
314 (12.6), 395 (3.0), 411 (2.9), 500 (0.29)
626 (2.4)[f]
623 (1.6)[f]
603 (1.6)[f]
530 (220), 577 (220)[g]
608 (1.7)[f]
606 (1.7)[f]
601 (10)[f]
–
0.19
0.29
0.04
<0.01
–
607 (11)[f]
618 (1.2)
605 (4.6)
519 (770), 563
solid (298)
solid (77)
DMF/MeOH/EtOH (1:1:4) (77)
–
–
–
–
–
A
[a] Absorption maxima. [b] At 1”10À5 m. [c] Emission maxima. [d] Self-quenching of emission is not observed. [e] Emission quantum yield. [f] At 2”
10À5 m. [g] At 4”10À5 m.
samples to 77 K. In glassy solution (DMF/MeOH/EtOH,
1:1:4, 4”10À5 m), the emission is vibronically structured with
peak maxima at 519–577 nm. The spacings of 1300–
1400 cmÀ1 correspond to the skeletal vibrational frequencies
of the C=C/C=N entities of the (RC^N^N) ligands; there-
E0–0 transitions were estimated from the emission maxima of
the complexes in alcoholic glassy solution at 77 K. These
calculations ignore the differences between E0–0 and the
emission maxima, in addition to any effect from employing
different solvents in electrochemical and spectroscopic
measurements; we are only interested in the relative trend
in the excited state reduction potential of these complexes.
3
fore, we can assign these emissions as coming from a IL ex-
cited state.
1
The E = * values for those complexes with an auxiliary Cl
2
Excited state reduction potential: The excited state reduc-
ligand (1a–1 f), found at 0.5–0.6 V versus Cp2Fe+/0, are the
À
tion potential (E = *), defined by Ptn*+e !
[Ptn]À (n=1, 2,
lowest among the PtII
ACHTREUNG
1
2
3), of [(RC^N^N)PtX]
A
ACHTREUNG
A
G
U
mononuclear
and
dinuclear
6-phenyl-2,2’-bipyridyl
(C^N^N) congeners (0.9–1.4 V).[13,15,16] The other mononu-
using the equation E = *=E = +E0–0
and compared to the
(PPh3)](ClO4), [4-EtO2C-
(ClO4), [4,4’-tBu2(C^N^N)2Pt2(dppm)]-
[{4-EtO2C(C^N^N)}2Pt2(dppm)](ClO4)2 and
[(C^N^N)2Pt2 E = values from the first rever-
(dppm)]2+
sible reduction wave were used in these calculations. The
clear complexes with PPh3 and PCy3 (3c, 4b and 4c) have
1
values for [4,4’-tBu
(C^N^N)Pt(PPh3)]
(ClO4)2,
U
E = * values of 0.8–0.9 V. Of the dinuclear complexes, 2a and
2
1
E
N
2c have low E = * values (0.6 V), while 2b, 2d, 2e and 2 f
2
E
G
have higher values of between 0.7 and 0.9 V versus Cp2Fe+/0
.
1
The E = * values of the trinuclear complexes 5b and 5d are
2
0.7 and 0.9 V versus Cp2Fe+/0, respectively.
428
www.chemeurj.org
ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2007, 13, 417 – 435

Platinum(II) Complexes with Cyclometalated Ligands
FULL PAPER
Figure 8. Absorption (top) and emission (bottom) spectra of 5d in
MeCN, CH2Cl2, MeOH and DMF solution. Inset: expanded e values
versus wavelength plots in the 350 to 600 nm region.
Figure 7. Absorption (top) and emission (bottom) spectra of 2d in
MeCN, CH2Cl2, MeOH and DMF solution.
Electroluminescence of 1a and 1d: The [(RC^N^N)PtCl]
complexes possess high PL quantum yields and thermal sta-
bilities yet they can be easily sublimed in vacuo. These prop-
erties render them suitable for applications in OLEDs. The
OLEDs in this work were fabricated with 1–6% of 1a or 1d
as the emitting dopant. The devices containing 1a have the
following configuration: ITO (indium tin oxide)/NPB (4,4’-
5% (device A) gave the best performance. This device is a
yellow-green light emitter; a strong emission was observed
with peak maxima at 532 and 570 nm and a shoulder at
about 610 nm, which could be attributed to the triplet excit-
ed state of 1a. A brightness of 1 cdmÀ2 was obtained at 5 V.
The maximum brightness of 37400 cdmÀ2 was achieved at
20 V, and the maximum current efficiency of 15.4 cdAÀ1 was
reached at 0.2 mAcmÀ2.
OLEDs employing 1d (1–12%) were prepared in the fol-
lowing configuration: ITO/NPB (40 nm)/CBP:1d (x%,
30 nm)/BAlq3 (bis(2-methyl-8-quinolinolato)(4-phenylphe-
nolato)aluminum, 10 nm)/Alq3 (30 nm)/LiF (0.1 nm)/Al
(200 nm). Devices B (x=1%) and C (x=3%) gave the
highest maximum brightness and current efficiency, respec-
tively (Table 7). These devices are also yellowish-green light
emitters and have similar CIE coordinates (Table 7). The
EL lmax (540 and 592 nm, with a shoulder at about 640 nm)
is independent of the doping concentration for 1d. The
good performance of these devices can be correlated to the
high emission quantum yield, Td, and Tg of 1d. Device B
gave a brightness of 1 cdmÀ2 at 5 V, and a maximum current
efficiency of 12.5 cdAÀ1 was obtained at 1.8 mAcmÀ2. This
device is stable in terms of efficiency decay, and the efficien-
cy was attained at 5 cdAÀ1 when the current density was in-
bis[N-(1-naphthyl)-N-phenylamino]biphenyl
(4,4’-N,N’-dicarbazolebiphenyl):1a (x%, 30 nm)/BCP (bath-
ocuprine, 15 nm)/Alq3 (tris(8-quinolinolato)aluminium,
70 nm)/CBP
30 nm)/LiF (0.3 nm)/Al (130 nm). A data summary for these
devices is depicted in Table 7. A dopant concentration of
Table 7. EL data for 1a and 1d.
Device[a] Complex x[b] [%] Bmax [cdmÀ2
(V [V])[c]
]
CIE[d]
x, y
Effmax [cdAÀ1
(J
[mAcmÀ2])[e]
]
ACHTREUNG
A
B
C
1a
1d
1d
5
1
3
37000 (20)
63000 (20)
40000 (21)
0.37, 0.58 15.4 (0.2)
0.36, 0.54 12.5 (1.7)
0.38, 0.55 20.2 (0.4)
[a] Devices A, B, and C gave a brightness of 1 cdmÀ2 at 5 V. [b] Dopant
percentage of 1a or 1d. [c] Maximum brightness (Bmax) achieved at volt-
age V. [d] 1931 Commission Internationale de l’Éclairage coordinates at
achieved maximum brightness. [e] Maximum current efficiency (Effmax
achieved at current density J.
)
Chem. Eur. J. 2007, 13, 417 – 435
ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
429

C.-M. Che et al.
creased to 600 mAcmÀ2.
A
maximum brightness of
Conclusions
63000 cdmÀ2 was achieved at 20 V (Figure 9); this is signifi-
cantly higher than those yellow to yellowish-green OLEDs
In the past few years there has been an increasing interest
in luminescent platinum(II) complexes, especially those with
diimine and cyclometalated ligands, due to their possible ap-
plication as phosphorescent materials for organic light-emit-
ting devices.[15,16,19,32,33,41,43,47–53] The mono-, di- and trinuclear
(RC^N^N) complexes of platinum(II) reported in this work
are strongly emissive and have high emission quantum
yields in solutions at room temperature. The emission quan-
tum yield of 1d (0.68 in CH2Cl2) is significantly higher than
employing
the
6-phenyl-2,2’-bipyridyl
congener
[(C^N^N)PtR]+ (maximum luminance=7800 cdmÀ2, lmax
=
that of [(C^N^N)PtCl][13] and [Pt(tBu2N2O2)],[32] with the
G
latter two showing emission at 565 (F=0.025) and 595 nm
(F=0.12), respectively, in CH2Cl2 solutions (Table 8). The
3MMLCT excited states of [(RC^N^N)2Pt2
N
G
(2b) and [(RC^N^N)3Pt3
A
ACHTREUNG
emission quantum yield (0.35 for 2b and 0.33 for 5b) in so-
lution at room temperature, and this is quite uncommon for
di- and trinuclear platinum(II) complexes. There are several
unique features of the (RC^N^N) ligands that may account
for the high emission quantum yields of their PtII complexes:
1) the extended p-conjugation would increase the electronic
delocalization, hence a smaller bond displacement change in
the excited state compared to those for (C^N^N) analogues
is expected. This would lead to less effective non-radiative
decay;[54] 2) the rigid planar geometry of the (RC^N^N) li-
gands maintains the stereochemical integrity of the mononu-
clear complexes, and the extensive inter- and/or intramolec-
ular p···p interactions reduce molecular motions, particularly
at the flexible Pt-P-CH2-P-Pt moiety in the binuclear com-
plexes, and discourage excited state distortions, thereby re-
ducing non-radiative decay. The mononuclear Cl-containing
complexes 1a and 1c have an almost planar geometry that
enables close intermolecular interplanar contacts. The dinu-
clear complexes 2c, 2d and 2 f exhibit an eclipsed overlap of
Figure 9. J–V–B (current density–voltage–brightness) relationships of
device B.
564 nm),[15] [Pt(N2O2)] (4480 cdmÀ2
; CIE x=0.42, y=
A
0.56),[33] Pt Schiff-base complexes (23000 cdmÀ2; CIE x=
0.48, y=0.52),[41] [(O^N^N)PtCl] ((O^N^N)=derivatives of
6-(2-hydroxyphenyl)-2,2’-bipyridyl; maximum luminance=
37000 cdmÀ2, CIE x=0.48, y=0.51),[32] [(X-bt)Pt
(acac)]
G
(11320 cdmÀ2 at 14 V; CIE x=0.47, y=0.51; X-bt=substi-
tuted 2-phenylbenzothiazolato (X=H or F); acac=acetyla-
cetonate),[42] [Pt
(N^N)2] ((N^N)=5-(2-pyridyl)-3-trifluoro-
U
methylpyrazole; maximum luminance=41000 cdmÀ2, CIE
x=0.42, y=0.53; Table 8)[43] and other non-Pt emitters as
dopants.[44–46]
Table 8. Comparison of the properties of the platinum(II) light-emitting materials.
OLED Device Performance
[a]
[b]
[c]
[d]
Complex
lmaxPL
Fem
Td
lmaxEL
CIE[e]
x[f]
Bmax
Effmax
[cdAÀ1
(J
[mAcmÀ2])[h]
[nm]
[8C]
[nm]
x, y
[%]
A
]
G
]
(V [V])[g]
ACHTREUNG
1a
1d
529 (CH2Cl2)
533 (CH2Cl2)
565 (CH2Cl2)
582 (CH2Cl2)
560 (CH2Cl2)
616 (CH2Cl2)
606 (DMF)
600 (DMF)
593 (DMF)
618 (DMF)
606 (DMF)
0.20 (CH2Cl2)
0.68 (CH2Cl2)
0.025 (CH2Cl2)
0.04 (CH2Cl2)
0.06 (CH2Cl2)
0.04 (CH2Cl2)
0.01 (DMF)
0.02 (DMF)
0.03 (DMF)
0.01 (DMF)
0.04 (DMF)
0.12 (CH2Cl2)
–
470
532
285
~400
~400
~400
388
421
425
351
426
530
–
532, 570
540, 592
–
564
548
612
564
565
564
572
566
540
–
0.37, 0.58
0.38, 0.55
–
5
1
–
4
4
4
6
5
6
6
5
0.3
5
37000 (20)
63000 (20)
–
15.4 (0.2)
12.5 (1.7)
–
A
[j]
ꢂ
A
0.48, 0.48
0.44, 0.51
0.59, 0.34
0.48, 0.50
0.51, 0.48
0.50, 0.49
0.53, 0.46
0.48, 0.51
–
7800 (11)
9800 (12)
3100 (12)
6000 (16)
14000 (16)
26000 (14)
10000 (19)
37000 (16)
9330 (À)
11320 (14)
41000 (15)
2.4 (30)
3.2 (20)
1.0 (30)
2.9 (4.4)
9.7 (4.2)
13 (1.4)
7.3 (2.9)
7.8 (89)
–
[j]
ꢂ
A
[j]
ꢂ
R
C
N
E
G
R
A
595 (CH2Cl2)
531, 571 (CH2Cl2)
595 (solid state)
C
R
0.47, 0.51
0.42, 0.53
16 (2)
20 (20)
H
0.24 (solid state)
–
560
20
[a] Peak maximum of photoluminescence. [b] Emission quantum yield in solution. [c] Decomposition temperature. [d] Peak maximum of electrolumines-
cence. [e] 1931 Commission Internationale de l’Éclairage coordinates. [f] Dopant percentage of platinum(II) complex. [g] Maximum brightness (Bmax
)
achieved at voltage V. [h] Maximum current efficiency (Effmax) achieved at current density J. [i] Reference [13]. [j] Reference [15]. [k] Reference [32].
[l] Reference [33]. [m] Reference [42]. [n] Reference [43].
430
www.chemeurj.org
ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2007, 13, 417 – 435

Platinum(II) Complexes with Cyclometalated Ligands
FULL PAPER
(silica gel, n-hexane/CHCl3 =9:1 as eluent). The structures and number-
ing schemes of a–f for NMR peak assignment are depicted in Figure 1.
the (RC^N^N) moieties with torsion angles close to 08. In
previous reports on [Pt(C^N^N)] systems, shorter Pt···Pt
A
A
distances are accompanied by a larger torsion angle between
the two (C^N^N)Pt moieties. This was attributed to a mini-
mal repulsive effect between the (C^N^N) ligands in a stag-
gered rather than an eclipsed conformation.[35] The extensive
(1.00 g, 2.66 mmol), 3-dimethylamino-1-(2’-naphthyl)propanone hydro-
chloride salt (0.70 g, 2.7 mmol) and ammonium acetate (5.00 g,
64.9 mmol) gave a as an off-white solid. Yield: 0.53 g (60%); 1H NM R
(300 MHz, CDCl3, 258C, TMS): d=7.5–7.6 (m, 2H; H6 and H7), 7.7 (t,
3JH,H =8 Hz, 1H; H21), 7.8 (t, 3JH,H =9 Hz, 1H; H20), 7.9–8.1 (m, 7H; H3,
H5, H8, H12, H13, H19 and H22), 8.4 (dd, 4JH,H =2, 3JH,H =10 Hz, 1H; H2),
p···p interactions in [(RC^N^N)2Pt2
N
N
evident from the torsion angles in 2c, 2d and 2 f (1.88, 0.28
and 0.28, respectively), which are significantly smaller than
4
3
8.5 (dd, JH,H =1, JH,H =9 Hz, 1H; H14), 8.7 (s, 1H; H10), 9.1 (s, 1H; H24),
9.4 ppm (s, 1H; H17); MS (70 eV, EI): m/z 332 [M+].
that in [(C^N^N)2Pt2
(m-dppm)]2+ (44.68, Table 4). The
N
(tBuC^N^NH) (b): 1-(2-(3’-Isoquinolinyl)-2-oxoethyl)pyridinium iodide
(0.47 g, 1.3 mmol), tert-butylidene-2-acetonaphthone (0.30 g, 1.3 mmol)
and ammonium acetate (5.00 g, 64.9 mmol) gave b as an off-white solid.
[(RC^N^N)PtCl] complexes have been demonstrated to be
useful phosphorescent materials. High-performance light-
emitting devices have been fabricated from 1a and 1d; the
performances of these yellow OLEDs are significantly
better than those employing other platinum(II) complexes
in terms of both luminance and efficiency. For example, the
yellow OLED (EL lmax =536 nm) containing 1d as the emit-
ter exhibits a maximum luminance of 63000 cdmÀ2 and a
current efficiency of 12.5 cdAÀ1 at a current density of
1.8 mAcmÀ2, which are higher than those obtained with
[(O^N^N)PtCl] (566 nm, 37000 cdmÀ2 and 7.8 cdAÀ1 at
89 mAcmÀ2, Table 8). The outstanding performance of these
OLEDs can be related to the high emission quantum yields
of [(RC^N^N)PtCl]. Due to the ease of modifying the che-
lating cyclometalated ligand, these complexes represent a
new class of luminophores with tuneable excited-state prop-
erties. Along with their highly luminescent nature and ap-
preciable thermal stability (with Td up to around 5308C for
1d), cyclometalated (RC^N^N) systems of platinum(II)
with extended p-conjugation constitute a new class of light-
emitting materials with potential practical applications.
Yield: 0.27 g (55%); 1H NMR (300 MHz, CDCl3, 258C, TMS): d=1.5 (s,
3
9H; C
A
7.7 (t, 3JH,H =8 Hz, 1H; H20), 7.9 (m, 2H; H5 and H12), 8.0–8.1 (m, 4H;
H3, H8, H19 and H22), 8.4 (dd, 4JH,H =2, 3JH,H =5 Hz, 1H; H2), 8.6 (d,
4JH,H =1.6 Hz, 1H; H14), 8.6 (s, 1H; H10), 9.1 (s, 1H; H24), 9.4 ppm (s, 1H;
H17); MS (70 eV, EI): m/z 388 [M+].
A
(1.00 g, 2.66 mmol), benzylidene-2-acetonaphthone (0.69 g, 2.7 mmol)
and ammonium acetate (5.00 g, 64.9 mmol) gave c as a white solid. Yield:
1
3
0.87 g (80%); H NMR (400 MHz, CDCl3, 258C, TMS): d=7.5 (t, JH,H
=
6 Hz, 1H; H28), 7.5–7.6 (m, 4H; H5, H7 and H27), 7.7 (t, JH,H =8 Hz, 1H;
H21), 7.8 (t, 3JH,H =8 Hz, 1H; H20), 7.9–8.0 (m, 3H; H8 and H26), 8.0–8.1
(m, 4H; H3, H6, H19 and H22), 8.1 (s, 1H; H12), 8.5 (d, 3JH,H =5 Hz, 1H;
H2), 8.7 (s, 1H; H10), 8.8 (s, 1H; H14), 9.1 (s, 1H; H24), 9.4 ppm (s, 1H;
H17); MS (70 eV, EI): m/z 408 [M+].
3
(3,5-tBu2PhC^N^NH) (d): 1-(2-(3’-Isoquinolinyl)-2-oxoethyl)pyridinium
iodide (0.90 g, 2.4 mmol), 3’,5’-di-tert-butylbenzylidene-2-acetonaphthone
(0.89 g, 2.4 mmol) and ammonium acetate (5.00 g, 64.9 mmol) gave d as a
white solid. Yield: 0.89 g (72%); 1H NMR (400 MHz, CDCl3, 258C,
TMS): d=1.5 (s, 18H; C
(CH3)3), 7.6–7.7 (m, 6H; H6, H8, H21, H26 and
G
H28), 7.8 (t, 3JH,H =8 Hz, 1H; H20), 7.9–8.0 (m, 1H; H5), 8.0–8.1 (m, 5H;
3
H3, H7, H12, H19 and H22), 8.5 (d, JH,H =10 Hz, 1H; H2), 8.7 (s, 1H; H10),
8.8 (s, 1H; H14), 9.1 (s, 1H; H24), 9.4 ppm (s, 1H; H17); MS (70 eV, EI):
m/z 520 [M+].
(3,5-F2PhC^N^NH) (e): 1-(2-(3’-Isoquinolinyl)-2-oxoethyl)pyridinium
iodide (1.91 g, 5.19 mmol), 3’,5’-difluorobenzylidene-2-acetonaphthone
(1.53 g, 5.19 mmol) and ammonium acetate (5.00 g, 64.9 mmol) gave e as
a white solid. Yield: 2.03 g (88.1%); 1H NMR (400 MHz, CD2Cl2, 258C,
Experimental Section
General considerations: Solvents were purified according to literature
methods.[55] 3-Acetylisoqulinoline was prepared from 3-hydroxyisoqulino-
line by a Heck reaction.[56] 1-(2-(3’-Isoquinolinyl)-2-oxoethyl)pyridinium
iodide was prepared by heating 3-acetylisoqulinoline with excess I2 in
pyridine for 2 h.[57–59] 3-Dimethylamino-1-(2’-naphthyl)propanone hydro-
chloride salt was synthesized by refluxing 2-acetylnaphthalene, parafor-
maldehyde and dimethylamine hydrochloride in the presence of conc.
HCl in 95% ethanol for 24 h.[59] The a,b-unsaturated ketones were pre-
pared according to literature methods.[60,61] The (RC^N^NH) ligands a–f
were prepared by modification of published procedures.[62] Electron-
impact (EI) and fast atom bombardment (FAB) mass spectra were ob-
3
TMS): d=7.0 (t, JH,F =9 Hz, 1H; H28), 7.4–7.5 (m, 2H; H26), 7.6 (m, 2H;
H6 and H8), 7.7 (t, 3JH,H =8 Hz, 1H; H21), 7.8 (t, 3JH,H =8 Hz, 1H; H20),
3
8.0 (m, 1H; H5), 8.0–8.1 (m, 5H; H3, H7, H14, H19 and H22), 8.5 (d, JH,H
=
10 Hz, 1H; H2), 8.7 (s, 1H; H10), 8.8 (s, 1H; H12), 9.1 (s, 1H; H24),
9.4 ppm (s, 1H; H17); 19F NMR (376 MHz, CD2Cl2, 258C): d=
3
À109.6 ppm (t, JH,F =8 Hz); MS (70 eV, EI): m/z 444 [M+].
A
N
iodide (0.95 g, 2.5 mmol), 3’,5’-bis(trifluoromethyl)benzylidene-2-aceto-
naphthone (1.00 g, 2.54 mmol) and ammonium acetate (5.00 g,
64.9 mmol) gave
f as a
white solid. Yield: 1.2 g (85%); 1H NM R
1
tained with a Finnigan Mat 95 mass spectrometer. H and 31P NMR spec-
(400 MHz, CDCl3, 258C, TMS): d=7.5–7.6 (m, 2H; H6 and H8), 7.7 (t,
tra were recorded with Bruker AVANCE 600, DRX 400 and 500 FT-
NMR spectrometers. The 1H NMR chemical shifts were referenced to
those of the residual proton/carbon atoms of CD3CN, [D7]DMF, CDCl3
or CD2Cl2. H3PO4 was used in the 31P NMR study as external reference.
3JH,H =9 Hz, 1H; H21), 7.8 (t, JH,H =8 Hz, 1H; H20), 7.9–8.0 (m, 1H; H5),
3
8.0–8.1 (m, 6H; H3, H7, H12, H19 and H22), 8.3 (s, 2H; H26), 8.4 (d, JH,H
=
3
10 Hz, 1H; H2), 8.7 (s, 1H; H10), 8.8 (s, 1H; H14), 9.1 (s, 1H; H24),
9.4 ppm (s, 1H; H17). 19F NMR (376 MHz, 258C, TMS): d=À62.6 ppm;
MS (70 eV, EI): m/z 544 [M+].
1
Peak assignments were based on results of H–1H and NOESY 2D NMR
experiments. Elemental analyses were performed at the Institute of
Chemistry of the Chinese Academy of Science in Beijing.
Synthesis of [(RC^N^N)PtCl] (1a–1 f)
Synthesis of (RC^N^NH) (a–f)
General procedure: Refluxing a mixture of K2PtCl4 and the correspond-
ing (RC^N^NH) (a–f) in glacial acetic acid (100 mL) for 24 h gave 1a–
1 f as a yellow suspension. The yellow solid was isolated by filtration,
washed with water and acetone, and recrystallized from CH2Cl2 (for 1a,
1c and 1d) or DMF (for 1b, 1e and 1 f). Complexes 1a–1 f are insoluble
in most organic solvents; they are slightly soluble in [D7]DMF but the
solubility is too low to allow for 13C NMR measurements. The structure
General procedure: Heating a mixture of 1-(2-(3’-isoquinolinyl)-2-oxo-
ethyl)pyridinium iodide, 3-dimethylamino-1-(2’-naphthyl)propanone hy-
drochloride salt (for a) or the corresponding a,b-unsaturated ketone (for
b–f) and excess ammonium acetate in methanol (100 mL) for 24 h gave
a–f. The crude product was filtered from the solution mixture, washed
with water and cold methanol, and purified by column chromatography
Chem. Eur. J. 2007, 13, 417 – 435
ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
431

C.-M. Che et al.
and numbering scheme of 1a–1 f for NMR peak assignment are depicted
in Figure 1.
obtained at À20 to À308C. The structures and numbering scheme of 2a–
2 f for NMR peak assignment are depicted in Figure 1.
A
(m-dppm)]
U
U
U
dppm (0.034 g, 0.089 mmol) and LiClO4 (0.50 g, 4.7 mmol) gave 2a as
yellow crystals. Yield: 0.12 g (80%); 1H NMR (500 MHz, CD3CN,
À308C): d=5.1 (t, 2JH,P =13 Hz, 2H; PCH2P), 5.6 (d, 3JH,H =8 Hz, 2H;
0.30 mmol) were used. Complex 1a was isolated as a yellow, crystalline
solid. Yield: 0.13 g (80%); 1H NMR (400 MHz, [D7]DMF, 258C, TMS):
d=7.4 (t, 3JH,H =7 Hz, 1H; H6), 7.5 (t, 3JH,H =7 Hz, 1H; H7), 7.8 (d,
3JH,H =9 Hz, 1H; H8), 7.9 (d, 3JH,H =9 Hz, 1H; H5), 8.0 (t, 3JH,H =7 Hz,
1H; H21), 8.1–8.2 (m, 2H; H3 and H20), 8.2–8.3 (m, 2H; H14 and H19),
8.3–8.4 (m, 3H; H10, H12 and H13), 8.6 (t, 3JH,H =8.5 Hz, 1H; H22), 9.2 (s,
1H; H24), 9.8 ppm (s, 1H; H17); MS (+FAB): m/z 562 [M+]; elemental
analysis calcd (%) for C24H15ClN2Pt (561.9): C 51.30, H 2.69, N 4.99;
found: C 51.10, H 2.69, N 4.99.
H22), 6.4 (s, 2H; H17), 6.8 (d, 3JH,H =8 Hz, 2H; H8), 6.9 (t, 3JH,H =7 Hz,
3
2H; H7), 7.0 (d, 3JH,H =8 Hz, 2H; H5), 7.0 (s, 2H; H10), 7.1 (t, JH,H
=
7 Hz, 2H; H21), 7.2–7.3 (m, 4H; H3 and H6), 7.6 (d, 3JH,H =8 Hz, 2H;
H12), 7.7 (t, 3JH,H =8 Hz, 2H; H20), 7.8 (d, 3JH,H =8 Hz, 2H; H14), 7.9 (d,
3JH,H =8 Hz, 2H; H19), 8.0 (t, JH,H =8 Hz, 2H; H13), 8.3 ppm (s, 2H; H24);
3
the 20 protons of the phenyl rings in dppm: 7.0–7.1 (m, 2H), 7.2 (t,
3JH,H =7 Hz, 2H), 7.4–7.5 (m, 4H), 7.6 (t, 3JH,H =8 Hz, 2H), 7.7–7.8 (m,
4H), 8.2 (dd, 3JH,H =8, 3JH,P =14.2 Hz, 2H), 8.4 (t, 3JH,H =9 Hz, 2H),
8.6 ppm (t, 3JH,H =8 Hz, 2H); 31P NMR (162 MHz, CD3CN, 258C): d=
19.4 ppm (1JP, Pt =4138 Hz); MS (+FAB): m/z 1437 [M+À2ClO4]; elemen-
tal analysis calcd (%) for C73H52Cl2N4O8P2Pt2 (1636.3): C 53.59, H 3.20, N
3.42; found: C 52.74, H 3.25, N 3.39.
A
3.58 mmol) were used. Complex 1b was isolated as a yellow, crystalline
solid. 1H NMR spectroscopic data are not available due to the low solu-
bility of 1b in various deuterated solvents. Yield: 1.90 g (85.9%); MS
(+FAB): m/z 618 [M+]; elemental analysis calcd (%) for C28H23ClN2Pt
(618.0): C 54.42, H 3.75, N 4.53; found: C 52.74, H 3.95, N 4.60.
A
(m-dppm)]
U
(2b):
Complex
1b
(0.10 g,
G
0.16 mmol), dppm (0.031 g, 0.081 mmol) and LiClO4 (0.50 g, 4.7 mmol)
gave 2b as a yellow, crystalline solid. Yield: 0.098 g (70%); 1H NM R
(500 MHz, CD3CN, À408C): d=1.5 (s, 18H; tBu), 5.1 (d, 3JH,H =8 Hz,
1.3 mmol) were used. Complex 1c was isolated as yellow crystals. Yield:
0.72 g (90%); 1H NMR (400 MHz, [D7]DMF, 258C, TMS): d=7.4 (t,
3JH,H =8 Hz, 1H; H6), 7.4 (t, 3JH,H =8 Hz, 1H; H7), 7.6–7.7 (m, 3H; H10
2H; H22), 5.2 (t, 2JH,P =12 Hz, 2H; PCH2P), 6.5 (s, 2H; H17), 7.0–7.1 (m,
and H26), 7.7 (d, 3JH,H =8 Hz, 1H; H8), 7.8 (d, 3JH,H =8 Hz, 1H; H5), 7.9
3
8H; H3, H6, H10 and H21), 7.2 (t, 3JH,H =9 Hz, 2H; H7), 7.3 (d, JH,H
=
3
(t, 3JH,H =7 Hz, 1H, H21), 8.0 (t, 3JH,H =8 Hz, 1H; H20), 8.1 (d, JH,H
=
3
8 Hz, 2H; H5), 7.4; (d, JH,H =8 Hz, 2H; H8), 7.4 (s, 2H; H12), 7.7 (s, 2H;
8 Hz, 1H; H19), 8.2 (m, 3H; H27 and H28) 8.4–8.5 (m, 2H; H14 and H22),
8.6 (s, 1H; H12), 9.3 (s, 1H; H24), 9.7 ppm (s, 1H; H17); MS (+FAB): m/z
638 [M+]; elemental analysis calcd (%) for C30H19ClN2Pt (638.0): C
56.48, H 3.00, N 4.39; found: C 56.04, H 3.02, N 4.50.
H14), 7.8 (t, 3JH,H =8 Hz, 2H; H20), 7.9 (d, 3JH,H =8 Hz, 2H; H19), 8.4 ppm
3
(s, 2H; H24); the 20 protons of the phenyl rings in dppm: 6.9 (t, JH,H
=
8 Hz, 2H), 7.0–7.1 (m, 2H), 7.3 (t, 3JH,H =8 Hz, 2H), 7.5 (t, 3JH,H =7 Hz,
3
3
3
2H), 7.6 (dd, JH,H =7, JH,P =14 Hz, 2H), 7.7 (t, JH,H =8 Hz, 2H), 7.7–7.8
(m, 2H), 8.1 (dd, 3JH,H =8, 3JH,P =14 Hz, 2H), 8.4 (t, 3JH,H =9 Hz, 2H),
8.6 ppm (t, 3JH,H =9 Hz, 2H); 31P NMR (162 MHz, CD3CN, 258C): d=
18.0 ppm (1JP, Pt =4084 Hz). MS (+FAB): m/z 1550 [M+À2ClO4]; elemen-
tal analysis calcd (%) for C81H68Cl2N4O8P2Pt2 (1748.5): C 55.64, H 3.92, N
3.20; found: C 54.85, H 4.01, N 3.85.
[(3,5-tBu2PhC^N^N)PtCl] (1d): K2PtCl4 (0.50 g, 1.2 mmol) and d (0.63 g,
1.2 mmol) were used. Complex 1d was isolated as an orange, crystalline
solid. Yield: 0.73 g (80%); 1H NMR (400 MHz, [D7]DMF, 258C, TMS):
d=7.4 (t, 3JH,H =7 Hz, 1H; H6), 7.4 (t, 3JH,H =6.7 Hz, 1H; H7), 7.7 (d,
3JH,H =7 Hz, 1H; H8), 7.8 (m, 2H; H5 and H28), 7.9 (t, 3JH,H =7 Hz, 1H;
H21), 8.0–8.1 (m, 5H; H3, H19, H20 and H26), 8.4–8.5 (m, 3H; H10, H14 and
H22), 8.6 (s, 1H; H12), 9.3 (s, 1H; H24), 9.7 ppm (s, 1H; H17); MS
(+FAB): m/z 751 [M+]; elemental analysis calcd (%) for C38H35ClN2Pt
(750.2): C 60.84, H 4.70, N 3.73; found: C 60.91, H 4.77, N 3.80.
A
(m-dppm)]
G
N
dppm (0.046 g, 0.12 mmol) and LiClO4 (0.50 g, 4.7 mmol) gave 2c as a
yellow, crystalline solid. Yield: 0.19 g (86%); 1H NMR (500 MHz,
3
2
[D7]DMF, À308C): d=5.6 (d, JH,H =8 Hz, 2H; H22), 5.9 (t, JH,P =138 Hz,
2H; PCH2P), 6.8 (s, 2H; H17), 6.9 (d, JH,H =8 Hz, 2H; H8), 7.1 (t, JH,H
=
3
3
[(3,5-F2PhC^N^N)PtCl] (1e): K2PtCl4 (0.79 g, 1.9 mmol) and e (0.85 g,
1.9 mmol) were used. Complex 1e was isolated as a yellow, crystalline
solid. Yield: 1.1 g (88%); 1H NMR (400 MHz, [D7]DMF, 258C, TMS):
d=7.3 (t, 3JH,H =8 Hz, 1H; H6), 7.3 (t, 3JH,H =8 Hz, 1H; H7), 7.5 (d,
3JH,H =8 Hz, 1H; H8), 7.6 (d, 3JH,H =7.8 Hz, 1H; H5), 7.7–7.8 (m, 4H; H3
H21 and H26), 7.9 (t, 3JH,H =7 Hz, 1H; H20), 8.0 (d, 3JH,H =8 Hz, 1H; H19),
8.1 (d, 3JH,H =8 Hz, 1H; H22), 8.2 (s, 2H; H10 and H12), 8.42 (s, 1H; H14),
9.04 (s, 1H; H24), 9.29 ppm (s, 1H; H17); 19F NMR (376 MHz, [D7]DMF,
7 Hz, 2H; H7), 7.2 (t, 3JH,H =7 Hz, 2H; H21), 7.3–7.4 (m, 6H; H3, H5 and
H6), 7.6 (t, 3JH,H =8 Hz, 4H; H27), 7.7 (t, 3JH,H =7 Hz, 2H; H28), 7.8 (s,
2H; H10), 7.9–8.0 (m, 2H; H20), 8.0 (d, 3JH,H =8 Hz, 4H; H26), 8.1 (d,
3JH,H =8 Hz, 2H; H19), 8.6 and 8.7 (2 s, 4H; H12 and H14), 9.4 ppm (s, 2H;
H24); the 20 protons of the phenyl rings in dppm: 7.3–7.4 (m, 4H), 7.7 (t,
3JH,H =7 Hz, 4H), 7.9–8.0 (m, 4H), 8.0–8.1 (m, 2H), 8.5 (t, 2H), 8.9 (t,
3JH,H =8 Hz, 2H), 9.3 ppm (t, 3JH,H =9 Hz, 2H); 31P NMR (202 MHz,
[D7]DMF, 258C): d=20.2 ppm (1JP, Pt =4125 Hz); MS (+FAB): m/z 1590
[M+À2ClO4]; elemental analysis calcd (%) for C85H60Cl2N4O8P2Pt2
(1788.5): C 57.09, H 3.38, N 3.13; found: C 56.28, H 3.41, N 3.51.
3
258C): d=À110.13 ppm (t, JH,F =8 Hz); MS (+FAB): m/z 674 [M+]; ele-
mental analysis calcd (%) for C30H17ClF2N2Pt (674.0): C 53.46, H 2.54, N
4.16; found: C 53.14, H 2.42, N 4.47.
[(3,5-tBu2PhC^N^N)2Pt2
A
G
N
A
N
0.16 mmol), dppm (0.032 g, 0.083 mmol) and LiClO4 (0.50 g, 4.7 mmol)
gave 2d as a yellow, crystalline solid. Yield: 0.13 g (78%); 1H NM R
(500 MHz, CD2Cl2, À408C): d=1.3 (s, 36H; tBu), 5.0 (t, 2JH,P =13 Hz,
2H; PCH2P), 6.2 (d, 3JH,H =11 Hz, 2H; H22), 6.2 (s, 2H; H17), 6.3 (t,
3JH,H =7 Hz, 2H; H6), 6.8 (d, 3JH,H =8 Hz, 2H; H8), 6.9 (m, 4H; H5 and
(0.86 g, 1.6 mmol) were used. Complex 1 f was isolated as a yellow, crys-
talline solid. Yield: 1.1 g (92%); 1H NMR spectroscopic data are not
available because of the low solubility of 1 f in various deuterated sol-
vents. 19F NMR (376 MHz, [D7]DMF, 258C): d=À62.1 ppm; MS
(+FAB): m/z 774 [M+]; elemental analysis calcd (%) for C32H17ClF6N2Pt
(774.0): C 49.66, H 2.21, N 3.62; found: C 49.67, H 2.01, N 3.72.
3
H7), 7.1 (s, 2H; H3), 7.3 (t, JH,H =8 Hz, 2H; H21), 7.4 (s, 4H; H26), 7.5 (s,
2H; H28), 7.7 (t, J=8 Hz, 2H; H20), 7.8 (s, 2H; H10), 7.9 (s, 2H; H12), 8.0
(d, 3JH,H =8 Hz, 2H; H19), 8.3 (s, 2H; H14), 8.7 ppm (s, 2H; H24); the 20
Synthesis of [(RC^N^N)2Pt2
A
(ClO4)2
A
3
protons of the phenyl rings in dppm: 7.2–7.3 (m, 6H), 7.6 (t, JH,H =7 Hz,
General procedure: dppm (0.55 equiv) was added to
a
solution of
3
3
3
2H), 7.7 (t, JH,H =8 Hz, 2H), 7.8 (t, JH,H =8 Hz, 2H), 7.9 (t, JH,H =8 Hz,
2H), 8.3 (t, 3JH,H =8 Hz, 2H), 8.4 (dd, 3JH,H =8, 3JH,P =14 Hz, 2H),
8.5 ppm (t, 3JH,H =9 Hz, 2H); 31P NMR (162 MHz, CD2Cl2, 258C): d=
19.4 ppm (1JP, Pt =4150 Hz); MS (+FAB): m/z 1914 [M+ÀClO4], 1814
[M+À2ClO4]; elemental analysis calcd (%) for C101H92Cl2N4O8P2Pt2
(2012.9): C 60.27, H 4.61, N 2.78; found: C 59.92, H 4.64, N 3.15.
[(RC^N^N)PtCl] in an acetonitrile/dichloromethane mixture (40 mL,
1:1) with stirring. A clear yellow solution was obtained, to which an
excess of LiClO4 (10 equiv) was added. (Caution! perchlorate salts are
potentially explosive and should be handled with care and in small
amounts). The mixture was stirred at room temperature for 12 h, filtered
and then concentrated on a rotary evaporator. Addition of diethyl ether
gave the crude product as a bright yellow solid, which was washed with
water and diethyl ether and recrystallized by diffusion of diethyl ether
[(3,5-F2PhC^N^N)2Pt2
A
(ClO4)2
A
0.09 mmol), dppm (0.018 g, 0.047 mmol) and LiClO4 (0.50 g, 4.7 mmol)
1
into an MeCN solution. Well-resolved H NMR spectra for 2a–2 f can be
gave 2e as a yellow, crystalline solid. Yield: 0.07 g (80%); 1H NM R
432
www.chemeurj.org
ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2007, 13, 417 – 435

Platinum(II) Complexes with Cyclometalated Ligands
FULL PAPER
(500 MHz, [D7]DMF, À208C): d=5.9 (t, 2JH,P =13 Hz, 2H; PCH2P), 6.0
(d, 3JH,H =8 Hz, 2H; H22), 6.7(s, 2H; H17), 6.8–6.9 (m, 4H; H5 and H6),
Cy), 2.1–2.2 (m, 6H; Cy), 2.6–2.7 (m, 3H; Cy), 7.3–7.4 (m, 2H; H20 and
H21), 7.5–7.56 (m, 3H; H27 and H28), 7.6–7.7 (m, 1H; H22), 7.7 (s, 1H;
3
3
3
7.1 (t, JH,H =7 Hz, 2H; H7), 7.2 (d, JH,H =8 Hz, 2H; H8), 7.3–7.4 (m, 4H;
H12), 7.7–7.8 (m, 1H; H19), 7.8–7.9 (m, 3H; H7 and H26), 8.0 (t, JH,H
=
3
3
H3 and H21), 7.62 (t, JH,F =9 Hz, 2H; H28), 7.9–8.0 (m, 6H; H20 and H26),
8 Hz, 1H; H6), 8.1 (s, 1H; H24), 8.1 (d, JH,H =7 Hz, 1H; H5), 8.2 (s, 1H;
H14), 8.2 (d, 3JH,H =8 Hz, 1H; H8), 8.3 (s, 1H; H17), 8.8 (s, 1H; H10),
9.4 ppm (s, 1H; H3); MS (+FAB): m/z 882 [M+ÀClO4]; elemental analy-
sis calcd (%) for C48H52ClN2O4PPt (982.5): C 58.68, H 5.33, N 2.85;
found: C 58.68, H 5.49, N 3.29.
8.0–8.1 (m, 4H; H10 and H19), 8.7 (s, 2H; H12), 8.8 (s, 2H; H14), 9.3 ppm
(s, 2H; H24); the 20 protons of the phenyl rings in dppm: 7.3–7.40 (m,
3
4H), 7.7–7.8 (m, 6H), 7.9–8.0 (m, 2H), 8.0–8.1 (m, 2H), 8.5 (dd, JH,H =8,
3JH,P =15 Hz, 2H), 8.8 (t, 3JH,H =9 Hz, 2H), 9.1 ppm (t, 3JH,H =8.6 Hz,
2H); 19F NMR (376 MHz, [D7]DMF): d=À109.2 ppm (d, 3JH,F =8 Hz);
31P NMR (202 MHz, [D7]DMF): d=19.9 ppm (1JP, Pt =4070 Hz); MS
(+FAB): m/z 1761 [M+ÀClO4], 1661 [M+À2ClO4]; elemental analysis
calcd (%) for C85H56Cl2F4N4O8P2Pt2 (1860.4): C 54.88, H 3.03, N 3.01;
found: C 53.94, H 3.32, N 3.83.
Synthesis of [(RC^N^N)3Pt3
N
N
General procedure: dpmp (0.33 equiv) was added to
a
solution of
[(RC^N^N)PtCl] in an acetonitrile/dichloromethane mixture (10 mL,
1:1) whilst stirring. A clear orange solution was obtained, to which excess
LiClO4 (10 equiv) was added. (Caution! Perchlorate salts are potentially
explosive and should be handled with care and in small amounts). The
mixture was stirred at room temperature for 12 h, filtered and concen-
trated. Addition of diethyl ether gave the crude product as a bright
yellow solid, which was washed with water and diethyl ether and recrys-
tallized by diffusion of diethyl ether into an acetonitrile solution. Since
there are many non-equivalent protons in 5b and 5d, the peaks in the ar-
A
(CF3)2PhC^N^N)2Pt2
U
U
U
0.19 mmol), dppm (0.037 g, 0.10 mmol) and LiClO4 (0.50 g, 4.7 mmol)
were used to gave 2 f as an orange, crystalline solid. Yield: 0.18 g (90%);
1H NMR (500 MHz, [D7]DMF, À308C): d=5.9 (t, 2JH,P =13 Hz, 2H;
3
PCH2P), 6.4 (d, 3JH,H =9 Hz, 2H; H22), 6.4 (s, 2H; H17), 6.5 (t, JH,H
=
7 Hz, 2H; H7), 6.7 (d, 3JH,H =8 Hz, 2H; H8), 7.0 (t, JH,H =7 Hz, 2H; H6),
7.2 (d, 3JH,H =8 Hz, 2H; H5), 7.5 (s, 2H; H3), 7.5–7.6 (m, 4H; H19 and
H21), 8.0 (t, 3JH,H =7.6 Hz, 2H; H20), 8.2 (s, 2H; H10), 8.45 (s, 2H; H28),
8.8 (s, 4H; H26), 9.0 (s, 2H; H12), 9.1 (s, 2H; H14), 9.2 ppm (s, 2H; H24);
the 20 protons of the phenyl rings in dppm: 7.4–7.5 (m, 4H), 7.5–7.6 (m,
2H), 7.8 (t, 3JH,H =7 Hz, 2H), 7.84 (t, 3JH,H =8 Hz, 2H), 7.9–8.0 (m, 2H),
8.0–8.1 (m, 2H), 8.6 (t, 3JH,H =11 Hz, 2H), 8.8 (t, 3JH,H =8 Hz, 2H),
3
1
omatic region of their H NMR spectra were not assigned.
A
G
(ClO4)3
G
0.10 mmol), dpmp (0.017 g, 0.034 mmol) and LiClO4 (0.5 g, 4.7 mmol)
gave 5b as a yellow, crystalline solid. Yield: 0.077 g (88%); 1H NM R
(400 MHz, CD2Cl2, 248C): d=1.3 (s, 9H, tBu(central)), 1.5 ppm (s, 18H,
T
tBu(terminal)); protons in the aromatic region were not assigned;
H
9.1 ppm (t, JH,H =11 Hz, 2H); 19F NMR (376 MHz, [D7]DMF, 258C): d=
3
31P NMR (162 MHz, CD2Cl2, 248C): d=8.8 (1JP, Pt =4150 Hz, central),
À62.5 ppm; 31P NMR (162 MHz, [D7]DMF, 258C): d=19.9 ppm (1JP, Pt
=
10.7 ppm (1JP, Pt =4057 Hz, terminal); 195Pt NMR (107 MHz, CD2Cl2,
4184 Hz); MS (+FAB): m/z 1962 [M+ÀClO4], 1862 [M+À2ClO4]; ele-
mental analysis calcd (%) for C89H56Cl2F12N4O8P2Pt2 (2060.4): C 51.88, H
2.74, N 2.72; found: C 51.76, H 2.88, N 2.87.
1
248C): d=À3917.0 (d, 1JP, Pt =3959, terminal), À3779.7 ppm (d, JP, Pt
=
3980, central); MS (+FAB): m/z 2250 [M+À3ClO4]; elemental analysis
calcd (%) for C116H98Cl3N6O12P3Pt3 (2552.6): C 54.58, H 3.87, N 3.29;
found: C 54.23, H 3.52, N 3.12.
Synthesis of [(RC^N^N)PtX](ClO4) (3c: X=PPh3; 4b,4c: X=PCy3)
A
General procedure: PPh3 or PCy3 was added to a solution of the corre-
sponding [(RC^N^N)PtCl] complex in a mixture of MeCN (20 mL) and
CH2Cl2 (20 mL) whilst stirring. Excess LiClO4 was then added to the
clear yellow solution. (Caution! Perchlorate salts are potentially explosive
and should be handled with care in small amounts.) After stirring at room
temperature for 12 h, the mixture was filtered and the filtrate was con-
centrated. Addition of diethyl ether to the concentrated filtrate gave the
crude product as a bright yellow solid, which was washed with water and
diethyl ether. The solid was recrystallized by vapor diffusion of diethyl
ether into a MeCN solution.
[(3,5-tBu2PhC^N^N)3Pt3
A
G
G
0.133 mmol), dpmp (0.022 g, 0.044 mmol) and LiClO4 (0.5 g, 4.7 mmol)
gave 5d as an orange, crystalline solid. Yield: 0.28 g (71%); 1H NM R
(400 MHz, CD2Cl2, 248C): d=1.2 (s, 18H; tBu(central)), 1.3 ppm (s,
U
36H; tBu(terminal)); protons in the aromatic region were not assigned;
E
31P NMR (162 MHz, CD2Cl2, 248C): d=9.7 (1JP, Pt =4042 Hz, central),
11.7 ppm (1JP, Pt =4094 Hz, terminal); 195Pt NMR (107 MHz, CD2Cl2,
248C): d=À3886.5 (d, 1JP, Pt =4070, terminal), À3727.8 ppm (d, JP, Pt
=
1
3995, central); MS (+FAB): m/z 2650 [M+À3ClO4]; elemental analysis
calcd (%) for C146H134Cl3N6O12P3Pt3 (2949.2): C 59.46, H 4.58, N 2.85;
found: C 59.11, H 4.65, N 2.73.
A
N
PPh3 (0.04 g, 0.2 mmol) and excess LiClO4 (0.50 g, 4.7 mmol) in MeCN/
X-ray crystallography: Crystals were mounted either inside a sealed ca-
pillary or on a thin glass fibre. Intensity data were collected at À208C on
a MAR diffractometer with a 300-mm image plate detector using graph-
ite-monochromated Mo-Ka radiation (l=0.71073 Š). The images were
interpreted and intensity was integrated with the program DENZO.[63]
All structures were solved by direct methods implemented in the SIR-
97[64] program on a PC. The heavy atoms (such as Pt and P) were initially
located in the partial structure solution from Fourier syntheses. The posi-
tions of other non-hydrogen atoms were located after a few cycles of re-
finement based on full-matrix least-squares of jF2 j using the SHELXL-
97 program suite.[65] Solvent molecules and/or perchlorate anions in 1a,
1c, 2a–2d, 2 f, 3c, 4b, 4c and 5b were found to be disordered and split
occupancy factors (55:45) were assigned to each component of the same
CH2Cl2 gave 3c as yellow crystals. Yield: 0.10 g (80%); 1H NM R
3
(400 MHz, [D7]DMF, 258C): d=6.9 (d, JH,H =8 Hz, 1H; H22), 6.9 (s, 1H;
H19), 7.3–7.4 (m, 3H; H8, H20 and H21), 7.5 (s, 1H; H3), 7.6–7.7 (m, 9H;
3
m-Ph, H27 and H28), 7.7 (t, JH,H=9 Hz, 3H; p-Ph), 7.8 (d, 3JH,H =9 Hz,
1H; H19), 7.9 (t, 3JH,H =8 Hz, 1H; H6), 8.1 (t, 3JH,H =8 Hz, 1H; H7), 8.1–
8.2 (m, 7H; H5 and o-Ph), 8.3 (d, 3JH,H =10 Hz, 2H; H26), 8.8 (s, 1H;
H24), 8.9 (s, 1H; H12), 9.0 (s, 1H; H14), 9.5 ppm (s, 1H; H10); MS
(+FAB): m/z 864 [M+ÀClO4]; elemental analysis calcd (%) for
C48H34ClN2O4PPt (964.3): C 59.79, H 3.55, N 2.91; found: C, 58.88, H
3.48, N 3.05.
A
N
PCy3 (0.015 g, 0.054 mmol) and excess LiClO4 (0.50 g, 4.7 mmol) in
MeCN/CH2Cl2 gave 4b as yellow crystals. Yield: 0.03 g (60%); 1H NM R
(300 MHz, CD3CN, 258C): d=1.1–1.3 (m, 9H; Cy), 1.6 (s, 9H; tBu), 1.6–
1.8 (m, 15H; Cy), 2.2–2.3 (m, 6H; Cy), 2.7–2.8 (m, 3H; Cy), 7.4–7.6 (m,
2H; H20 and H21), 7.8 (d, 3JH,H =7.9 Hz, 1H; H19), 7.9 (d, 3JH,H =8 Hz,
1H; H22), 7.9–8.0 (m, 2H; H7 and H24), 8.1 (t, 3JH,H =5 Hz, 1H; H6), 8.2–
8.3 (m, 3H; H5, H12 and H14), 8.4 (s, 1H; H17), 8.5 (d, 3JH,H =8 Hz, 1H;
H8), 9.0 (s, 1H; H10), 9.6 ppm (s, 1H; H3); MS (+FAB): m/z 863 [M+
ÀClO4]; elemental analysis calcd (%) for C46H56ClN2O4PPt·2CH3CN
(1044.6): C 57.49, H 5.98, N 5.36; found: C 56.99, H 5.92, N 5.06.
À
constrained thermal parameters. C Cl distances of 1.720ꢁ0.005 Š were
applied to all the CHCl3 and CH2Cl2 molecules. The positions of all aro-
matic hydrogen atoms were calculated from the idealized restrained posi-
À
tions (a riding model) with a fixed C H distance of 0.96 Š. Isotropic
thermal parameters of all hydrogen atoms were constrained to the value
of 1.2-times those of the attached carbons.
Organic-light emitting devices (OLEDs): The electroluminescent (EL)
devices were prepared on patterned indium-tin-oxide (ITO) glass with a
sheet resistance of 20 W/&. Thermal vacuum deposition of the materials
was carried out sequentially under a vacuum of 1”10À6 Torr in a thin-
film deposition system (an MBraun three-glove box system integrated
with an Edwards Auto 306 and spin coater instrument). The devices were
encapsulated using anodized aluminum caps and their performance was
A
N
PCy3 (0.04 g, 0.1 mmol) and excess LiClO4 (0.50 g, 4.7 mmol) in MeCN/
CH2Cl2 gave 4c as yellow crystals. Yield: 0.098 g (75%); 1H NM R
(400 MHz, CD3CN, 258C): d=1.1–1.3 (m, 9H; Cy), 1.6–1.7 (m, 15H;
Chem. Eur. J. 2007, 13, 417 – 435
ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
433

C.-M. Che et al.
examined with a Photoresearch PR-650. The current–voltage characteris-
tics were studied with a Keithley 2400 sourcemeter.
[26] F. Barigelletti, B. Ventura, J.-P. Collin, R. Kayhanian, P. Gavina, J.-P.
Sauvage, Eur. J. Inorg. Chem. 2000, 113–119.
[27] E. C. Constable, R. P. G. Henney, T. A. Leese, D. A. Tocher, J.
Chem. Soc. Dalton Trans. 1990, 443–449.
[28] W. Lu, M. C. W. Chan, K. K. Cheung, C. M. Che, Organometallics
2001, 20, 2477–2486.
[29] P. H. M. Budzelaar, gNMR version 4.1.0., Cherwell Scientific Pub-
lishing, 1999.
Acknowledgments
[30] CCDC-287984–287992, CCDC-601687, and CCDC-601688 contain
the supplementary crystallographic data for 1c, 2a–2d, 2 f, 3c, 4b,
4c, 1a, and 5b, respectively. These data can be obtained free of
charge via www. ccdc.cam.ac.uk/data_request/cif.
[31] D. A. Bardwell, J. G. Crossley, J. C. Jeffery, A. G. Orpen, E. Psillakis,
E. E. M. Tilley, M. D. Ward, Polyhedron 1994, 13, 2291–2300.
[32] C. C. Kwok, H. M. Y. Ngai, S. C. Chan, I. H. T. Sham, C. M. Che, N.
Zhu, Inorg. Chem. 2005, 44, 4442–4444.
We gratefully acknowledge financial support by the University Develop-
ment Fund (Nanotechnology Research Institute, 00600009) of The Uni-
versity of Hong Kong, Research Grants Council of HKSAR, China
(HKU 7039/03P), Innovation and Technology Commission of the
HKSAR Government (ITF GHP/062/05) and National Science Founda-
tion of China/Research Grants Council Joint Research Scheme (N_HKU
742/04).
[33] Y. Y. Lin, S. C. Chan, M. C. W. Chan, Y. J. Hou, N. Zhu, C. M. Che,
Y. Liu, Y. Wang, Chem. Eur. J. 2003, 9, 1263–1272.
[34] C. Janiak, J. Chem. Soc. Dalton Trans. 2000, 3885–3896.
[35] C. A. Hunter, J. K. M. Sanders, J. Am. Chem. Soc. 1990, 112, 5525–
5534.
[1] S. W. Lai, C. M. Che, Topics in Current Chemistry, Vol. 241: Transi-
tion Metal and Rare Earth Compounds III: Excited States, Transi-
tions, Interactions (Ed.: H. Yersin), Springer, New York, 2004, pp.
27–63.
[36] C. M. Che, L. Y. He, C. K. Poon, T. C. W. Mak, Inorg. Chem. 1989,
28, 3081–3083.
[2] C. E. Whittle, J. A. Weinstein, M. W. George, K. S. Schanze, Inorg.
Chem. 2001, 40, 4053–4062.
[37] A. F. Stange, T. Sixt, W. Kaim, Chem. Commun. 1998, 469–470.
[38] K. T. Wan, C. M. Che, K. C. Cho, J. Chem. Soc. Dalton Trans. 1991,
1077–1080.
[39] J. A. Bailey, M. G. Hill, R. E. Marsh, V. M. Miskowski, W. P. Schae-
fer, H. B. Gray, Inorg. Chem. 1995, 34, 4591–4599.
[40] V. H. Houlding, V. M. Miskowski, Coord. Chem. Rev. 1991, 111,
145–152.
[41] C. M. Che, S. C. Chan, H. F. Xiang, M. C. W. Chan, Y. Liu, Y. Wang,
Chem. Commun. 2004, 1484–1485.
[42] I. R. Laskar, S.-F. Hsu, T.-M. Chen, Polyhedron 2005, 24, 881–888.
[43] S.-Y. Chang, J. Kavitha, S.-W. Li, C.-S. Hsu, Y. Chi, Y.-S. Yeh, P.-T.
Chou, G.-H. Lee, A. J. Carty, Y.-T. Tao, C.-H. Chien, Inorg. Chem.
2006, 45, 137–146.
[44] X. Q. Lin, B. J. Chen, X. H. Zhang, C. S. Lee, H. L. Kwong, S. T.
Lee, Chem. Mater. 2001, 13, 456–458.
[45] M. Mazzeo, D. Pisignano, L. Favaretto, G. Barbarella, R. Cingolani,
G. Gigli, Synth. Met. 2003, 139, 671–673.
[46] S. Lamansky, P. Djurovich, D. Murphy, F. Abdel-Razzaq, H. E. Lee,
C. Adacjo, P. E. Burrows, S. R. Forrest, M. E. Thompson, J. Am.
Chem. Soc. 2001, 123, 4304–4312.
[47] W. Sotoyama, T. Satoh, N. Sawatari, H. Inoue, Appl. Phys. Lett.
2005, 86, 153505/1–153505/3.
[48] H. F. Xiang, S. C. Chan, K. K. Y. Wu, C. M. Che, P. T. Lai, Chem.
Commun. 2005, 1408–1410.
[49] J. Kavitha, S.-Y. Chang, Y. Chi, J.-K. Yu, Y.-H. Hu, P.-T. Chou, S.-M.
Peng, G.-H. Lee, Y.-T. Tao, C.-H. Chien, A. J. Carty, Adv. Funct.
Mater. 2005, 15, 223–229.
[50] W.-Y. Wong, Z. He, S.-K. So, K.-L. Tong, Z. Lin, Organometallics
2005, 24, 4079–4082.
[51] M. Cocchi, V. Fattori, D. Virgili, C. Sabatini, P. Di Marco, M. Maes-
tri, J. Kalinowski, Appl. Phys. Lett. 2004, 84, 1052–1054.
[52] B. W. D’Andrade, J. Brooks, V. Adamovich, M. E. Thompson, S. R.
Forrest, Adv. Mater. 2002, 14, 1032–1036.
[3] M. Hissler, J. E. McGarrah, W. B. Connick, D. K. Geiger, S. D. Cum-
mings, R. Eisenberg, Coord. Chem. Rev. 2000, 208, 115–137.
[4] B. Ma, J. Li, P. I. Djurovich, M. Yousufuddin, R. Bau, M. E. Thomp-
son, J. Am. Chem. Soc. 2005, 127, 28–29.
[5] C. Yu, K. M. C. Wong, K. H. Y. Chan, V. W. W. Yam, Angew. Chem.
2005, 117, 801–804; Angew. Chem. Int. Ed. 2005, 44, 791–794.
[6] S. D. Cummings, R. Eisenberg, J. Am. Chem. Soc. 1996, 118, 1949–
1960.
[7] W. B. Connick, V. M. Miskowski, V. H. Houlding, H. B. Gray, Inorg.
Chem. 2000, 39, 2585–2592.
[8] V. M. Miskowski, V. H. Houlding, Inorg. Chem. 1991, 30, 4446–
4452.
[9] H. K. Yip, C. M. Che, Z. Y. Zhou, T. C. W. Mak, J. Chem. Soc.
Chem. Commun. 1992, 1369–1371.
[10] V. M. Miskowski, V. H. Houlding, C. M. Che, Y. Wang, Inorg. Chem.
1993, 32, 2518–2524.
[11] C. W. Chan, L. K. Cheng, C. M. Che, Coord. Chem. Rev. 1994, 132,
87–97.
[12] S. W. Lai, M. C. W. Chan, K. K. Cheung, C. M. Che, Inorg. Chem.
1999, 38, 4262–4267.
[13] S. W. Lai, M. C. W. Chan, T. C. Cheung, S. M. Peng, C. M. Che,
Inorg. Chem. 1999, 38, 4046–4055.
[14] B. C. Tzeng, S. C. Chan, M. C. W. Chan, C. M. Che, K. K. Cheung,
S. M. Peng, Inorg. Chem. 2001, 40, 6699–6704.
[15] W. Lu, B. X. Mi, M. C. W. Chan, Z. Hui, N. Zhu, S. T. Lee, C. M.
Che, Chem. Commun. 2002, 206–207.
[16] W. Lu, M. C. W. Chan, N. Zhu, C. M. Che, C. Li, Z. Hui, J. Am.
Chem. Soc. 2004, 126, 7639–7651.
[17] J. A. Bailey, V. M. Miskowski, H. B. Gray, Inorg. Chem. 1993, 32,
369–370.
[18] L. Z. Wu, T. C. Cheung, C. M. Che, K. K. Cheung, M. H. W. Lam,
Chem. Commun. 1998, 1127–1128.
[19] W. Lu, B. X. Mi, M. C. W. Chan, Z. Hui, C. M. Che, N. Zhu, S. T.
Lee, J. Am. Chem. Soc. 2004, 126, 4958–4971.
[20] T. C. Cheung, K. K. Cheung, S. M. Peng, C. M. Che, J. Chem. Soc.
Dalton Trans. 1996, 1645–1651.
[53] S. C. Chan, M. C. W. Chan, Y. Wang, C. M. Che, K. K. Cheung, N.
Zhu, Chem. Eur. J. 2001, 7, 4180–4190.
[54] G. F. Strouse, J. R. Schoonover, R. Duesing, S. Boyde, W. E. J. Jones,
T. J. Meyer, Inorg. Chem. 1995, 34, 473–487.
[21] C. W. Chan, T. F. Lai, C. M. Che, S. M. Peng, J. Am. Chem. Soc.
1993, 115, 11245–11253.
[55] D. D. Perrin, W. L. F. Armarego, D. R. Perrin, Purification of Labo-
ratory Chemicals, 2nd ed. Pergamon, Oxford, 1980.
[56] J. Y. Legros, G. Primault, J. C. Fiaud, Tetrahedron 2001, 57, 2507–
2514.
[22] L. Chassot, A. Von Zelewsky, D. Sandrini, M. Maestri, V. Balzani, J.
Am. Chem. Soc. 1986, 108, 6084–6085.
[23] M. Maestri, D. Sandrini, V. Balzani, A. Von Zelewsky, P. Jolliet,
Helv. Chim. Acta 1988, 71, 134–139.
[57] R. G. Pearson, J. Am. Chem. Soc. 1947, 69, 3100–3103.
[58] L. C. King, M. McWhirter, R. L. Rowland, J. Am. Chem. Soc. 1948,
70, 239–242.
[24] M. Maestri, C. Deuschel-Cornioley, A. Von Zelewsky, Coord. Chem.
Rev. 1991, 111, 117–123.
[25] S. C. F. Kui, S. S. Y. Chui, C. M. Che, N. Zhu, J. Am. Chem. Soc.
2006, 128, 8297–8309.
[59] F. F. Blicke, J. H. Burckhalter, J. Am. Chem. Soc. 1942, 64, 451–454.
434
www.chemeurj.org
ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2007, 13, 417 – 435

Platinum(II) Complexes with Cyclometalated Ligands
FULL PAPER
[60] G. W. V. Cave, C. L. Raston, J. Chem. Soc. Perkin Trans. 1 2001,
3258–3264.
[61] F. Neve, A. Crispini, S. Campagna, Inorg. Chem. 1997, 36, 6150–
6156.
[62] P. S. Kendurkar, R. S. Tewari, J. Chem. Eng. Data 1974, 19, 184–188.
[63] DENZO: In the HKL Manual—A description of programs
DENZO, XDISPLAYF and SCALEPACK; written by D. Gewirth
with the cooperation of the program authors Z. Otwinowski and W.
Minor; Yale University: New Haven, CT (USA), 1995.
[64] A. Altomare, M. C. Burla, M. Camalli, G. L. Cascarano, C. Giaco-
vazzo, A. Guagliardi, A. G. G. Moliterni, G. Polidori, R. Spagna, J.
Appl. Crystallogr. 1999, 32, 115–119.
[65] G. M. Sheldrick, SHELXS-97, Programs for Crystal Structure Anal-
ysis (Release 97-2), University of Gçttingen, Germany, 1997.
Received: May 17, 2006
Revised: June 23, 2006
Published online: November 30, 2006
Chem. Eur. J. 2007, 13, 417 – 435
ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
435