Synthesis, spectroscopy, structures and photophysics of metal alkynyl complexes and polymers containing functionalized carbazole spacers

Article abstract of DOI:10.1016/j.jorganchem.2006.06.006

A new class of soluble and thermally stable group 10 platinum(II) poly-yne polymers functionalized with 9-arylcarbazole moiety trans-[-Pt(PBu₃)₂C{triple bond, long}CRC{triple bond, long}C-]_n (R = 9-arylcarbazole-3,6-diyl;

Full text of DOI:10.1016/j.jorganchem.2006.06.006

Journal of Organometallic Chemistry 691 (2006) 4028–4041
www.elsevier.com/locate/jorganchem
Synthesis, spectroscopy, structures and photophysics of metal alkynyl
complexes and polymers containing functionalized carbazole spacers
b,
b
c
Li Liu a,b, Wai-Yeung Wong *, Jian-Xin Shi , Kok-Wai Cheah ,
b
b
Tik-Ho Lee , Louis M. Leung
a
Ministry of Education Key Laboratory for the Synthesis and Application of Organic Functional Molecules, Faculty of Chemistry and Chemical Engineering,
Hubei University, Wuhan 430062, PR China
b
Department of Chemistry and Centre for Advanced Luminescence Materials, Hong Kong Baptist University, Waterloo Road,
Kowloon Tong, Hong Kong, PR China
c
Department of Physics and Centre for Advanced Luminescence Materials, Hong Kong Baptist University, Waterloo Road,
Kowloon Tong, Hong Kong, PR China
Received 27 March 2006; received in revised form 5 June 2006; accepted 5 June 2006
Available online 15 June 2006
Abstract
A new class of soluble and thermally stable group 10 platinum(II) poly-yne polymers functionalized with 9-arylcarbazole moiety
trans-[-Pt(PBu3)2C„CRC„C-]n (R = 9-arylcarbazole-3,6-diyl; aryl = p-methoxyphenyl, p-chlorophenyl) were prepared in good yields
by the polycondensation polymerization of trans-[PtCl2(PBu3)2] with HC„CRC„CH under ambient conditions. The optical absorption
and emission properties of these polymetallaynes were investigated and compared with their bimetallic molecular model complexes trans-
[Pt(Ph)(PEt3)2C„CRC„CPt(Ph)(PEt3)2] as well as their group 11 gold(I) and group 12 mercury(II) neighbors [(PPh3)AuC„CRC„
CAu(PPh3)] and [MeHgC„CRC„CHgMe]. The structures of all the compounds were confirmed by spectroscopic methods and by
X-ray crystallography for selected model complexes. The influence of the heavy metal atom and the 9-aryl substituent of carbazole
on the evolution of lowest electronic singlet and triplet excited states is critically characterized. It was shown that the organic-localized
phosphorescence emission can be triggered readily by the heavy-atom effect of group 10–12 transition metals (viz., Pt, Au, and Hg) with
the emission efficiency generally in the order Pt > Au > Hg. These carbazole-based organometallic materials possess high-energy triplet
states of 2.68 eV or higher which do not vary much with the substituent of 9-aryl group.
ꢀ 2006 Elsevier B.V. All rights reserved.
Keywords: Acetylide; Carbazole; Gold; Mercury; Platinum; Phosphorescence
1. Introduction
tain a rigid biphenyl unit which can lead to a large band
gap with efficient blue emission, and the facile substitution
at the remote N-position offers the possibility of improving
the solubility and processability of polymers without
remarkably increasing the steric interactions in the polymer
backbone [1].
While developments based on the exploitation of
9-arylcarbazole as the building unit for the synthesis of
branched molecules, oligomers, polymers or even dendri-
mers have been extensive, most of them are restricted to
purely organic systems [10]. Carbazole-based coordina-
tion/organometallic compounds have been much less
explored [11]. To our knowledge, carbazole-containing
The use of carbazole chromophores offers exciting per-
spectives for the design of new molecular and polymeric
materials for various optoelectronic applications [1]. Many
carbazole derivatives have a sufficiently high triplet energy
to be able to host red [2–5], green [6,7], and in some cases
even blue [8,9] triplet emitters. Poly(carbazole) homopoly-
mers and their copolymers are highly promising materials
for applications in light-emitting devices because they con-
*
Corresponding author. Tel.: +852 3411 7074; fax: +852 3411 7348.
E-mail address: rwywong@hkbu.edu.hk (W.-Y. Wong).
0022-328X/$ - see front matter ꢀ 2006 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2006.06.006

L. Liu et al. / Journal of Organometallic Chemistry 691 (2006) 4028–4041
4029
metal alkynyl compounds are still scarce. Literature exam-
ples are exclusively confined to 2,7-diethynyl-9-buty-
lcarbazolediyl-spaced metal di-, oligo- and polymers [12].
However, there has been no report of 9-arylcarbazolyl-
derived metal complexes, and the chemistry of such com-
pounds would be interesting within the realm of materials
science and optoelectronics. There are also very few reports
in the sensitization of carbazole’s triplet emission using
heavy-metal effects [10h]. According to the energy gap
law, the rate of phosphorescence emission is increased by
interruption of the p-conjugation, i.e. a compound with
high-energy triplet state is desirable [13]. With this in mind,
we report here the synthesis, spectroscopic characteriza-
tion, crystal structures and photophysical properties of
some luminescent group 10–12 dinuclear and polynuclear
platinum(II), gold(I) and mercury(II) complexes function-
alized with some 9-arylcarbazole spacers. The influence of
the heavy metal center and the 9-aryl substituent of carba-
zole ring on the photoluminescence behavior will be eluci-
dated in this contribution.
[PtCl(Ph)(PEt3)2] with Ia or Ib at room temperature (r.t.),
respectively. The feed mole ratios of 2:1 and 1:1 for the
platinum chloride precursors and the diethynyl ligand were
adopted for the model complex and polymer syntheses,
respectively. Purification of the polymers 1a and 1b were
accomplished by silica column chromatography using
CH2Cl2 as the eluent whereas the diplatinum complexes
2a and 2b were isolated by preparative TLC on silica. We
have also prepared the d10 digold(I) diacetylide counter-
parts 3a and 3b by reaction of Au(PPh3)Cl with Ia or Ib
in a 2:1 stoichiometry in the presence of a base [17]. Simi-
larly, complexes 4a and 4b, the isoelectronic and isolobal
analogues of 3a and 3b, were synthesized by treatment of
Ia and Ib with two equivalents of MeHgCl under similar
basic medium [18]. The yields of these transformations
are generally high in each case. All the new complexes
and polymers are air-stable solids which can be stored
without demanding any special precautions. They display
good solubility in chlorocarbons such as CH2Cl2 and
CHCl3, but are insoluble in hydrocarbons. Estimates of
the molecular weights using gel permeation chromatogra-
phy (GPC) in THF indicate that the degrees of polymeriza-
tion calculated from Mw are 8–16 for 1a and 1b (Table 1).
It should be noted that the GPC method used does not give
absolute values of molecular weights but can only measure
the hydrodynamic volume. Rod-like polymers in solution
possess different hydrodynamic properties than flexible
polystyrene standard. So, calibration of the GPC with
polystyrene is likely to inflate the values of the molecular
weights of the poly-ynes to some extent.
2. Results and discussion
2.1. Synthesis
The synthesis of 3,6-diethynyl-9-arylcarbazole, Ia and
Ib, are outlined in Scheme 1. First, the N-arylation of
carbazole was achieved by the modified Ullmann conden-
sation between carbazole and the corresponding p-iodo-
arene under the CuI/phen/KOH catalytic medium [14].
The corresponding N-arylated 3,6-dibromocarbazole pre-
cursors were obtained in good yields by bromination of
9-arylcarbazole derivatives with N-bromosuccinimide
(NBS). An alternative synthetic method can also be used
to produce 3,6-dibromo-9-arylcarbazoles in a similar yield
by condensing the commercially available 3,6-dibromocar-
bazole with the corresponding p-iodoarene. The 3,
6-bis(trimethylsilylethynyl)-functionalized 9-arylcarbazole
compounds were formed from the Sonogashira-type cou-
pling reaction between the dibromo derivatives and tri-
methylsilylacetylene and they were then converted to the
diethynyl counterparts Ia and Ib in very good yields (88–
94%) using K2CO3 in MeOH as the deprotecting reagent
[15]. The crude products from these reaction mixtures were
purified by passage through silica gel column and were
recrystallized where necessary.
All the metal alkynyl complexes and polymers were
obtained in good yields by the general alkynylation routes
as described in Scheme 1. The diplatinum complexes can be
considered the geometrical molecular models for the long
chain organometallic polymers. Organic ligands Ia and Ib
were employed as versatile synthons in the present study
to form a series of group 10–12 metal acetylide complexes
and polymers by adaptation of the classical dehydrohalo-
genation procedures reported in the literature [16]. 1a, 1b,
2a and 2b were synthesized by CuI-catalyzed dehydrohalo-
genating coupling of trans-[PtCl2(PBu3)2] or trans-
2.2. Spectroscopic properties
The IR, NMR (1H, 13C and 31P) and fast-atom bom-
bardment (FAB) mass spectral data of our compounds
agree with their chemical structures. The solution IR spec-
tra are each characterized by a single sharp m(C„C)
absorption band at ca. 2092–2134 cmꢀ1. The IR spectrum
of each compound shows no m(„CH) band in the range
3200–3300 cmꢀ1, in line with the fact that Ia and Ib are
completely being capped by the metal groups via r bonds.
The single 31P{1H} NMR signals flanked by platinum sat-
ellites for 1a, 1b, 2a and 2b are consistent with a trans
geometry of the square-planar Pt unit. The room-tempera-
ture 31P NMR spectrum of 3a and 3b display a sharp sin-
glet at d 43.91, indicative of a symmetrical arrangement
of PAuC„C groups in solution. 1H NMR resonances aris-
ing from the protons of the organic and phosphine moieties
were clearly observed. The formulas of the model com-
plexes 1a, 1b, 3a, 3b, 4a and 4b were also characterized
by the presence of intense molecular ion peaks in their
respective positive FAB mass spectra.
2.3. Crystal structure analyses
The three-dimensional molecular structures of 2a, 3a
and 4b were analyzed by X-ray crystallography and are

4030
L. Liu et al. / Journal of Organometallic Chemistry 691 (2006) 4028–4041
X
X
N
X
H
N
(i)
(ii)
+
N
I
Br
Br
(X = OMe, Cl)
X
N
(iii)
Me Si
3
SiMe
3
(iv)
X
N
X
N
X
N
(v)
(vi)
Bu P
3
PEt
Ph
Et P
3
3
H
H
Pt
Pt
Ia (X = OMe)
Ib (X = Cl)
Ph
PBu
PEt
Et P
3
3
3
(vii)
n
(viii)
2a (X = OMe)
2b (X = Cl)
1a (X = OMe)
1b (X = Cl)
X
N
X
N
(Ph P)Au
Au(PPh )
MeHg
3
3
HgMe
3a (X = OMe)
3b (X = Cl)
4a (X = OMe)
4b (X = Cl)
Scheme 1. (i) 1,10-phenanthroline, CuI, KOH, p-xylene, reflux; (ii) NBS, DMF, room temperature; (iii) trimethylsilylacetylene, Pd(OAc)2, PPh3, CuI,
iPr2NH, reflux; (iv) K2CO3, MeOH, room temperature; (v) trans-[PtCl2(PBu3)2] (1 equiv), CuI, iPr2NH, room temperature; (vi) trans-[PtPh(Cl)(PEt3)2] (2
i
equiv), CuI, Pr2NH, room temperature; (vii) Au(PPh3)Cl (2 equiv), NaOH/MeOH, room temperature; (viii) MeHgCl (2 equiv), NaOH/MeOH, room
temperature.
Table 1
cules in which two terminal organometallic groups are
linked by the 9-arylcarbazole-spaced bis(acetylide) moiety
Structural and thermal properties of the polymers 1a and 1b
Mw/Mn DPc Tdecomp (ꢁC)d % loss
a
b
Complex Mn
Mw
13,060 13,950 1.1
5550 6660 1.2
at the 3,6-position to afford the angular molecular skele-
ton. For the Pt(II) di-yne, there are two independent mol-
ecules per asymmetric unit in the unit cell and two half
molecules of 4b prevail in the unit cell of the Hg(II) com-
plex. The coordination geometry at the platinum center in
2a is square-planar with the two PEt3 groups trans to
each other and linear about the gold and mercury centers
in 3a and 4b. The C„C bond lengths in the ethynyl
1a
1b
a
16
8
343
350
5
5
25 (4Bu)e
38 (6Bu)e
Mn = Number – average molecular weight.
Mw = Weight – average molecular weight.
DP = Degree of polymerization.
Onset decomposition temperature.
The groups eliminated are shown in parentheses.
b
c
d
e
˚
depicted in Figs. 1–3 respectively. Pertinent bond dis-
tances and angles are given in Tables 2–4. In each case,
the crystal structure consists of discrete binuclear mole-
bridge [1.186(9)–1.27(2) A] are fairly typical of metal-alky-
nyl r-bonding [19]. The bond angles for the metal-alkynyl
units are close to linearity.

L. Liu et al. / Journal of Organometallic Chemistry 691 (2006) 4028–4041
4031
The mean Pt–P and Pt–C(alkynyl) distances of 2.284(3)
˚
and 2.004(10) A in 2a are analogous to those previously
reported for related platinum(II) alkynyls [19]. No appar-
ent short intermolecular contacts or p-stacking interactions
are observed in this Pt complex. The average Au–P bond
˚
length of 2.284(2) A in 3a is similar to those observed in
other alkynylgold(I) phosphine complexes, but longer than
those of the chlorogold(I) phosphines, in line with the
higher trans influence of the alkynyl group [17]. The Au–
C bond distances lie in the narrow range of 1.992(6)–
˚
2.010(7) A. Apparently, aurophilicity is absent in 3a, as
the sterically bulky phenyl groups of the phosphine ligands
probably prevent their close approach. While [MeHg]+ is
isoelectronic and isolobal with the [(PPh3)Au]+ fragment,
both 3a and 4b have similar structural motifs. The
˚
Hg–C(alkyne) bond (2.017(19)–2.065(19) A) is slightly
longer than the Au–C(alkyne) bond (1.992(6)–2.010(7) A).
Fig. 1. Molecular structure of 2a, with the atoms drawn at the 25%
probability level.
˚
Fig. 3. Molecular structure of 4b, with the atoms drawn at the 25%
Fig. 2. Molecular structure of 3a, with the atoms drawn at the 25%
probability level.
probability level.
Table 2
˚
Selected bond lengths (A) and angles (ꢁ) for 2a
Molecule 1
Molecule 2
Molecule 1
Molecule 2
Pt(1)–P(1)
Pt(1)–C(1)
Pt(2)–P(3)
Pt(2)–C(41)
C(19)–C(20)
C(40)–C(41)
N(1)–C(27)
2.281(3)
2.012(10)
2.280(3)
1.960(9)
1.205(14)
1.257(12)
1.401(11)
2.285(3)
2.092(10)
2.288(3)
2.017(10)
1.177(12)
1.219(12)
1.421(11)
Pt(1)–P(2)
Pt(1)–C(19)
Pt(2)–P(4)
Pt(2)–C(54)
C(20)–C(21)
C(39)–C(40)
C(30)–O(1)
2.285(3)
1.989(11)
2.282(3)
2.039(9)
1.455(13)
1.409(12)
1.376(12)
2.283(3)
2.051(10)
2.278(3)
2.077(10)
1.418(12)
1.453(12)
1.396(12)
P(1)–Pt(1)–P(2)
176.00(11)
87.8(3)
92.9(2)
175.2(9)
169.5(8)
174.05(12)
88.8(3)
92.2(3)
174.9(8)
169.1(8)
P(1)–Pt(1)–C(19)
P(3)–Pt(2)–P(4)
P(4)–Pt(2)–C(41)
C(19)–C(20)–C(21)
C(39)–C(40)–C(41)
88.2(3)
177.13(11)
86.7(2)
177.5(9)
176.7(10)
87.3(3)
170.94(13)
88.6(3)
176.1(10)
178.9(12)
P(2)–Pt(1)–C(19)
P(3)–Pt(2)–C(41)
Pt(1)–C(19)–C(20)
Pt(2)–C(41)–C(40)

4032
L. Liu et al. / Journal of Organometallic Chemistry 691 (2006) 4028–4041
Table 3
˚
Selected bond lengths (A) and angles (ꢁ) for 3a
P(1)–Au(1)
Au(1)–C(19)
C(19)–C(20)
C(40)–C(41)
N(1)–C(27)
2.2832(16)
1.992(6)
1.201(8)
1.186(9)
1.434(7)
P(2)–Au(2)
Au(2)–C(41)
C(20)–C(21)
C(39)–C(40)
C(30)–O(1)
2.2845(19)
2.010(7)
1.443(8)
1.459(9)
1.360(8)
P(1)–Au(1)–C(19)
Au(1)–C(19)–C(20)
C(19)–C(20)–C(21)
176.45(18)
174.3(6)
176.6(7)
P(2)–Au(2)–C(41)
Au(2)–C(41)–C(40)
C(39)–C(40)–C(41)
175.3(2)
175.4(6)
177.6(7)
˚
The Hg–CH3 bond (2.058–2.059 A) is slightly shorter than
those observed in some methylmercury(II) complexes with
˚
thiol ligand (2.082–2.133 A) [20]. The lattice structure of 4b
Fig. 4. Crystal packing diagram of 4b in a 3D network, showing weak
Hgꢁ ꢁ ꢁHg interactions.
is highlighted by the ligand-unsupported mercurophilicity,
and such interactions link the molecular units together to
form an organized 3D polymeric network (Fig. 4).
Remarkably, the whole lattice structure is fully supported
and stabilized by extensive non-covalent d10–d10 Hgꢁ ꢁ ꢁHg
nitrogen and both show good thermal stability with decom-
position temperatures at 343–350 ꢁC (Table 1). They are
more thermally stable than that for the corresponding
9-butylcarbazole analogue (315 ꢁC) [25], reflecting the
advantage of attaching the aromatic rings to the carbazole
nitrogen unit in enhancing the thermostability of these
polymetallaynes. The degradation patterns for these poly-
mers are very similar and the decomposition can be
assigned to the loss of various number of butyl groups
from the Pt poly-yne chains on the basis of the experimen-
tally observed % weight loss. These metallopolymers did
not display discernible glass transition in the DSC curves.
˚
interactive vectors (ca. 3.866 and 4.441 A). Although the
Hgꢁ ꢁ ꢁHg contacts indicate that each of the individual inter-
actions is relatively weak in nature, it is the large number of
them that play a supramolecular role and generate a signif-
icant driving force for the observation of solid-state aggre-
gation. There are good evidences that such mercurophilic
forces are more than just van der Waals interactions in
the present system. The van der Waals radius of mercury
˚
of up to 2.2 A has been proposed [21]. So, the observed
˚
Hgꢁ ꢁ ꢁHg separations are within the range of 3.71–4.25 A
for mononuclear [Hg(C„CR)2] (R = Ph, SiMe3) [22],
˚
3.738–4.183 A for binuclear [MeHgC„CRC„CHgMe]
2.5. Electronic absorption and luminescence spectra
(R = 9,9-dioctylfluorene-2,7-diyl and oligothienyl) [23]
˚
and 4.077 and 4.449 A computed for molecular (HgH2)n
We found that the platinum-containing polymers can
cast tough, free-standing thin films of good quality from
appropriate solvents for optical characterization. The
photophysical data of the new compounds measured in
both solution and solid phases are tabulated in Table 5.
All the metal alkynyls display similar structured absorption
bands in the near UV region. The lowest energy bands are
caused by the intraligand 1(pp*) transitions, possibly mixed
with contribution from some admixture of metal orbitals
[16a]. The 0–0 absorption peak is assigned as the transition
from the S0 to S1 states, which are predominantly delocal-
ized p and p* orbitals. As compared to the band in CH2Cl2
for the ligand, we find that the position of the lowest energy
absorption band is red-shifted after the inclusion of metal
fragment in metal di-ynes and polymers. This reveals that
p-conjugation is preserved through the metal site by mixing
clusters (n = 2,3) [24] and are toward the upper limit of
those accepted as representing metallophilic interactions
[21]. As shown in Fig. 4, the lattice is characterized by infi-
nite zig-zag chains of Hg atoms between adjacent mole-
cules (e.g. Hg(2A)ꢁ ꢁ ꢁHg(1F)ꢁ ꢁ ꢁHg(1C)ꢁ ꢁ ꢁHg(1H) and
Hg(1B)ꢁ ꢁ ꢁHg(1E)ꢁ ꢁ ꢁHg(1D)ꢁ ꢁ ꢁHg(1G)). This structure is
unique in that no apparent weak Hgꢁ ꢁ ꢁg2–C„C interac-
tions are observed which are commonly the driving force
for the solid-state aggregation process to be observed in
alkynyl complexes of CuI), Ag(I) and Hg(II) [18b,22b].
2.4. Thermal analysis
The thermal properties of the new metallopolymers were
examined by thermogravimetric analysis (TGA) under
Table 4
˚
Selected bond lengths (A) and angles (ꢁ) for 4b
Molecule 1
Molecule 2
Molecule 1
Molecule 2
Hg(1)–C(1)
C(2)–C(3)
N(1)–C(10)
2.059(16)
1.19(2)
1.42(2)
2.027(17)
1.27(2)
1.37(2)
Hg(1)–C(2)
C(3)–C(4)
Cl(1)–C(13)
2.065(19)
1.40(2)
1.716(18)
2.017(19)
1.400(19)
1.70(2)
Hg(1)–C(2)–C(3)
C(2)–C(3)–C(4)
172.6(15)
177.8(17)
171.1(15)
176.1(14)
C(1)–Hg(1)–C(2)
176.1(7)
179.0(7)

L. Liu et al. / Journal of Organometallic Chemistry 691 (2006) 4028–4041
4033
of the frontier orbitals of metal and the ligand. The transi-
tion energies of the polymers 1a and 1b are lowered with
respect to those of 2a and 2b, suggesting a well extended
singlet excited state in the former. The optical absorption
wavelengths of our compounds generally vary in the order
Ia(b) < 4a(b) < 3a(b) < 2a(b) < 1a(b). In other words, the
order of p-delocalization through the metal chromophore
is Pt(II) > Au(I) > Hg(II). On the other hand, the absorp-
tion spectra were found to be independent of the nature
of the aryl substituent on the carbazole ring, which are
related to the notion that the carbazolyl unit is not effective
in p-conjugation along the main chain. It is seen that car-
bazole tends to reduce conjugation relative to the
(C6H4)2-linked congeners, causing a blue-shift in the
absorption maxima [26].
The thin film photoluminescence (PL) spectra of the new
compounds were measured at various temperatures. In
dilute fluid solutions at 290 K, we observe an intense pur-
ple-blue 1(pp*) emission peak near 400 nm for each of them
which is assignable to fluorescence (S1 ! S0) due to the
short emission lifetimes (in the nanosecond range) and the
small Stokes shift between absorption and PL peaks.
The excitation spectra correspond well to the corresponding
absorption spectra. As the temperature is cooled down to
11 K, very intense organic-localized phosphorescence bands
become dominant in the spectra. The large Stokes shifts of
these lower-lying emission peaks from the dipole-allowed
absorptions (Figs. 5 and 6), plus the long PL lifetimes all
point to their triplet parentage, and they are assigned to
3
the (pp*) excited states of the diethynylcarbazole core
Table 5
Electronic absorption and emission data for metal alkynyl complexes and ligands
Compound
kmax (nm)a
Eg (eV)b
kem (nm)c
Frozen CH2Cl2 (77 K)e
d
CH2Cl2
film
CH2Cl2 (290 K)
Film (11 K)
1a
248
298
345
258
300
355
3.23
369*
399 (0.013, 6.6)
418
403*, 422*
462, 488, 511
545
454 (56.4)
478*
501*
1b
2a
2b
3a
249
300
344
259
300
354
3.21
3.46
3.46
3.31
370*
402 (0.008, 2.0)
419*
402*, 419*
461, 509*
541*
452 (40.1)
475*, 502*
259 (8.4)
301 (6.1)
329 (7.1)
260
302
334
384*
401 (0.028, 2.0)
418*
404*, 424*
456, 489* 502*
443 (47.2)
465*, 487*
258 (8.9)
303 (6.3)
330 (9.0)
258
302
334
377
404*, 422*
454, 474*,
486*, 500
441 (85.3)
464*, 484*
396 (0.029, 2.5)
415*
263 (6.1)
277 (4.6)
315 (7.5)
331* (4.8)
245
323
341
389
390*, 412*,
455, 480, 496
535*
433 (25.4)
458*, 471*
408 (0.019, 3.6)
3b
4a
4b
Ia
263 (6.3)
276 (5.0)
316 (8.8)
330* (6.1)
243
323
340
3.35
3.44
3.45
386
390*, 410*
455, 485, 498
435 (47.7)
461*, 473*
419 (0.020, 5.1)
260 (5.4)
269 (4.5)
300 (6.8)
322* (2.5)
265
311
331
380
384*, 404*
450, 477, 508*
427 (4.0)
453*
399 (0.007, 3.1)
420
260 (4.1)
298 (4.8)
320* (2.8)
266
310
330
373
381*, 402*
423*, 451
481, 495*
521*
425 (47.6)
450*
389 (0.016, 6.5)
406
255 (6.5)
288 (6.0)
258
293
3.84
3.84
369
385 (0.101)
402
Ib
253 (3.0)
287 (2.9)
258
293
368
385 (0.107)
402
a
Extinction coefficients (104 Mꢀ1 cmꢀ1) are shown in parentheses.
Estimated from the onset wavelength of the solid-state optical absorption.
Asterisks indicate that emission peaks appear as shoulders or weak bands.
Fluorescence quantum yields and lifetimes (in ns) shown in parentheses (UF, sF) are measured in CH2Cl2 relative to anthracene.
Phosphorescence lifetimes sP (in ls) at 77 K for the peak maxima are shown in parentheses.
b
c
d
e

4034
L. Liu et al. / Journal of Organometallic Chemistry 691 (2006) 4028–4041
0.5
1a
1b
T1
0.4
0.3
0.2
0.1
0.0
T1
11 K
77 K
150 K
290 K
2a
2b
T1
T1
x 10
400
500
600
700
(a)
Wavelength (nm)
200
300
400
500
600
700
Wavelength (nm)
0.4
0.3
0.2
0.1
0.0
Fig. 5. Room temperature optical absorption spectra (in CH2Cl2) and the
PL spectra of 1a, 1b, 2a and 2b (11 K in solid).
11 K
77 K
1a
2a
T1
150 K
290 K
T1
3a
4a
T1
400
500
600
700
(b)
Wavelength (nm)
Fig. 7. Temperature dependence of the PL of (a) 1a and (b) 1b.
T1
observed in similar systems reported in the literature
[16a]. Compared with the solution PL data, the solid-state
emission appears broad, structureless and red-shifted at
room temperature for the mercury acetylide compounds,
which is probably a result of interchain interactions due
to aggregate formation [27]. This is also consistent with
the X-ray structural data of 4b (vide supra).
200
300
400
500
600
700
Wavelength (nm)
Fig. 6. Room temperature optical absorption spectra (in CH2Cl2) and the
PL spectra of 1a, 2a, 3a and 4a (11 K in solid).
To examine the spatial extent of the singlet and triplet
excitons in the present system, the energy gaps between
S0 and T1 states were found to be 2.68–2.76 eV for our
metal di-ynes and poly-ynes (Table 6). For these 9-arylcar-
bazole-spaced metallaynes, they exhibit high T1 states
P2.68 eV, which appear even higher than those bridged
by some insulating Group 14 and 16 elements [13,28].
From Fig. 5, the phosphorescence spectra of the Pt com-
pounds generally follow the same trends as the absorption
features, in which the triplet emission peaks for the poly-
ynes are slightly red-shifted relative to those for the di-ynes.
It is obvious that the emission wavelength does not seem to
vary much with the type of spacer group in each series. In
addition, the energy of the T1 ! S0 transition changes with
the type of the metal groups and the PL spectra of different
metal complexes having the same organic chromophore are
compared in Fig. 10. For each metal class, a strong phos-
phorescence band was observed due to the presence of
strong spin–orbit coupling induced by the heavy metals,
[16]. The assignment was also supported by the observed
temperature dependence of the PL data, in accordance with
earlier work on related metal alkynyls [16]. The temperature
dependencies of the PL spectra for the polymers and some
model complexes are displayed in Figs. 7–9. In each case,
when the temperature is lowered, the triplet emission band
increases in intensity sharply in contrast to the singlet emis-
sion and a well-resolved vibronic substructure becomes
apparent. For instance, from 290 to 11 K, the singlet emis-
sion peak intensity increases only by a factor of 2.0 for 1a,
but the intensity of the lower-lying emission increases by a
factor of 62.0. Such an intensity rise is indicative of a
long-lived triplet excited state that is more sensitive to ther-
mally activated non-radiative decay mechanisms. There is
also a slight variation in the relative intensities of the vib-
ronic structures with temperature for these compounds
[16a]. The phosphorescence lifetimes (sP) at the peak max-
ima were found to be in the microsecond regime at 77 K
(Table 5), in line with those for the phosphorescence

L. Liu et al. / Journal of Organometallic Chemistry 691 (2006) 4028–4041
4035
0.05
0.04
0.03
0.02
0.01
0.00
11 K
11 K
0.12
77 K
77 K
150 K
290 K
0.08
150 K
290 K
0.04
0.00
400
500
600
700
400
500
600
700
(a)
(a)
Wavelength (nm)
Wavelength (nm)
0.25
0.20
0.15
0.10
0.05
0.00
0.8
0.6
0.4
0.2
0.0
11 K
11 K
77 K
77 K
150 K
290 K
150 K
290 K
400
500
600
700
400
500
600
700
(b)
Wavelength (nm)
(b)
Wavelength (nm)
Fig. 9. Temperature dependence of the PL of (a) 4a and (b) 4b.
Fig. 8. Temperature dependence of the PL of (a) 3a and (b) 3b.
of carbazolyl unit shifts the absorption and the phospho-
rescence bands to the blue compared to the related systems
with more conjugated aromatic and heteroaromatic spac-
ers. These new polymer systems enable the study of the
relationship between chemical structure and triplet energy
levels in conjugated polymers and materials and such an
investigation is desirable for optoelectronic applications
that harvest the spin-forbidden phosphorescent state for
more efficient light emission.
and there is a small but notable shift in the wavelength to
the blue from Pt to Au followed by Hg, in line with the
absorption trend. To access the relative intersystem cross-
ing efficiency, the peak height ratio from triplet emission
to singlet emission at 11 K, DE(S1 ! S0, T1 ! S0), was
taken as a useful indicator (Table 6) [29]. We note a very
high efficiency of triplet emission for the Pt polymers in
each system and the intersystem crossing is much stronger
in polymer than in the corresponding Pt di-yne. The order
of S1–T1 crossover efficiency is roughly: 1a(b) > 2a(b) > 3a
(b) > 4a(b). In other words, with the same ligand chromo-
phore, the relative intersystem crossing rate or phosphores-
cence efficiency is the highest for the Pt(II) compounds and
the lowest for the corresponding Hg(II) congener.
4. Experimental
4.1. General procedures
All the reactions were performed under an atmosphere
of nitrogen using standard Schlenk techniques, but no spe-
cial precautions were taken to exclude oxygen during
workup. Analytical grade solvents were purified by distilla-
tion over appropriate drying agent prior to use. All
reagents and chemicals, unless otherwise stated, were pur-
chased from commercial sources and used as received.
The compounds trans-[PtPh(Cl)(PEt3)2] [30], trans-[PtCl2-
(PBu3)2] [31], 9-arylcarbazole [32] and 3,6-dibromo-9-
(p-methoxyphenyl)carbazole [32] were prepared according
to literature methods. Caution! Organomercurials are
extremely toxic, and all experimentation involving these
3. Concluding remarks
Our present work reports the synthesis and characteriza-
tion of some group 10–12 metal-containing dinuclear and
polymeric compounds with 9-arylcarbazole moiety and
each of them exhibits interesting electronic and phospho-
rescence properties. Optical spectroscopy suggests that
while the carbazolyl group is weak in electronic conjuga-
tion, the resulting organometallic materials show strong
triplet emission with negligible fluorescence intensity at
low temperatures. The reduced conjugation in the presence

4036
L. Liu et al. / Journal of Organometallic Chemistry 691 (2006) 4028–4041
Table 6
Packard 8453 UV–Vis spectrometer. The solution emission
spectra were measured on a PTI Fluorescence Master Ser-
ies QM1 spectrophotometer. For solid state emission spec-
tral measurement, the 325 nm line of a He–Cd laser was
used as an excitation source. The photoluminescence spec-
tra were analyzed by a 0.25 m focal length double mono-
chromator with a Peltier cooled photomultiplier tube and
processed with a lock-in amplifier. For the low temperature
measurements, samples were mounted in a closed-cycle
cryostat (Oxford CC1104) in which the temperature can
be adjusted from 10 to 330 K. The fluorescence quantum
yields (UF) were determined in dichloromethane solutions
at 290 K against the anthracene standard (UF = 0.27)
[33]. The molecular weights of the polymers were
determined by GPC (HP 1050 series HPLC with visible
wavelength and fluorescent detectors) in THF using poly-
styrene standards and thermal analyses were performed
with the Perkin–Elmer Pyris Diamond DSC-50 and Perkin
TGA6 thermal analyzers at a heating rate of 20 ꢁC/min.
Experimental values of various transition energies among the S0, S1 and T1
levels and intersystem crossing efficiencies of platinum(II), gold(I) and
mercury(II) di-ynes and poly-ynes in the solid state at 11 K
a
Compound S1 ! S0 S0 ! S1 T1 ! S0 T1 ! S0
DE(S1 ! S0,
T1 ! S0)b
1a
1b
2a
2b
3a
3b
4a
4b
3.06
3.07
3.10
3.09
3.17
3.18
3.23
3.25
3.49
3.50
3.71
3.71
3.64
3.65
3.75
3.76
2.68
2.68
2.72
2.73
2.72
2.72
2.76
2.75
2.73
2.74
2.80
2.81
2.86
2.85
2.90
2.92
310
183
108
95
61
85
19c
9c
All energy units are in eV.
a
The data were estimated from the PL spectra in CH2Cl2 glass at 77 K.
Ratio of the intensities of triplet emission to singlet emission at 11 K.
The presence of broad aggregate emission band will probably lead to
b
c
some uncertainties and underestimation of the data.
4.2. Preparations of ligands
1.0
0.8
0.6
0.4
0.2
0.0
4.2.1. Synthesis of 3,6-bis(trimethylsilylethynyl)-9-(p-
methoxyphenyl)carbazole
To an ice-cooled mixture of 3,6-dibromo-9-(p-methoxy-
phenyl)carbazole (750.0 mg, 1.74 mmol) in freshly distilled
iPr2NH (50 cm3) under nitrogen, CuI (4.4 mg, 0.02 mmol),
Pd(OAc)2 (4.2 mg, 0.02 mmol) and PPh3 (12.9 mg,
0.05 mmol) were added. The solution was stirred for
20 min and Me3SiC„CH (427.2 mg, 4.35 mmol) was then
added. The reaction mixture was stirred for 30 min in an
ice bath before being warmed to room temperature. After
reacting for 30 min at room temperature, the mixture was
heated to 85 ꢁC for 20 h. The completion of the reaction
was verified by IR spectroscopy and spot TLC. The solvent
was evaporated to dryness, the residue redissolved in Et2O
(100 cm3) and the solution washed with dilute HCl
(2 · 100 cm3) followed by water (2 · 100 cm3). Upon filtra-
tion through a short pad of celite, the filtrate was washed
with saturated NaHCO3 (2 · 100 cm3) and water
(2 · 100 cm3) and the resulting organic solution was dried
over anhydrous MgSO4. The brown–yellow residue was
chromatographed over a silica gel column using hexane
as the eluent. The crude product was eluted as a light yel-
low band and the pure fraction was evaporated to dryness
and recrystallized from a solvent mixture of hexane and
CH2Cl2 to give 3,6-bis(trimethylsilylethynyl)-9-(p-meth-
oxyphenyl)carbazole as a yellow solid in 90% yield
350
400
450
500
550
600
Wavelength (nm)
Fig. 10. Phosphorescence spectra of 1a (ꢁ ꢁ ꢁ), 2a (- - -), 3a (—) and 4a (- -)
ÆÆ
at 77 K.
reagents should be performed in a well-vented hood.
Glasswares were oven-dried at about 120 ꢁC. Separation
or purification of products were achieved by preparative
thin-layer chromatography (TLC) on glass plates (20 cm
· 20 cm) coated with Merck Kieselgel 60GF254 prepared
in our laboratory (0.7 mm) or column chromatography
on silica.
Infrared spectra were recorded in dichloromethane on a
Perkin Elmer FTIR 550 spectrometer, using CaF2 cells
with a 0.5 cm path length. The 1H, 13C and 31P NMR spec-
tra were recorded on a JEOL JNM-EX270 FT NMR sys-
tem or a VARIAN 400 MHz NMR spectrometer, using
deuterated solvents as the lock and reference. Chemical
1
(730.0 mg). IR (CH2Cl2): m(C„C) 2152 cmꢀ1. H NMR
(CDCl3): d 8.18 (s, br, 2H, Ar), 7.40 (d, J = 8.1 Hz, 2H,
Ar), 7.09–7.00 (m, 4H, Ar), 6.87 (d, J = 8.1 Hz, 2H, Ar),
3.73 (s, 3H, OMe), 0.30 (s, 18H, SiMe3) ppm. 13C NMR
(CDCl3): d 158.52, 140.68, 129.68, 128.53, 127.59, 123.99,
121.94, 114.59, 114.22, 109.27 (Ar), 105.96, 91.81 (C„C),
55.06 (OMe) ppm. FAB-MS: m/z 466 [M+]. Anal. Calc.
for C29H31NOSi2: C, 74.79; H, 6.71; N, 3.01. Found: C,
74.62; H, 6.50; N, 2.93%.
1
shifts were reported in ppm relative to SiMe4 for H and
13C nuclei and 85% H3PO4 for 31P nucleus. The positive-
ion fast atom bombardment (FAB) mass spectra were
obtained using Finnigan-MAT SSQ710 mass spectrometer.
Electronic absorption spectra were obtained with a Hewlett

L. Liu et al. / Journal of Organometallic Chemistry 691 (2006) 4028–4041
4037
4.2.2. Synthesis of Ia
residue following evaporation was chromatographed over
a silica gel column by elution with hexane. The desired
product was isolated as a yellow solid in 77% yield
(0.79 g) after recrystallization from hexane/CH2Cl2. IR
3,6-Bis(trimethylsilylethynyl)-9-(p-methoxyphenyl)car-
bazole (782.5 mg, 1.68 mmol) was dissolved in Et2O
(10 cm3) to give a colorless solution and a catalytic amount
of K2CO3 (232.2 mg, 1.68 mmol) in MeOH (10 cm3) was
added. A milky solution was obtained after 24 h at room
temperature. The solvent was removed and the crude prod-
uct was purified by silica column chromatography eluting
with CH2Cl2 to afford a light yellow solid of 3,6-diethy-
1
(CH2Cl2): m(C„C) 2151 cmꢀ1. H NMR (CDCl3): d 8.18
(s, br, 2H, Ar), 7.49 (d, J = 8.9 Hz, 2H, Ar), 7.45–7.42
(m, 2H, Ar), 7.24 (d, J = 8.9 Hz, 2H, Ar), 7.10 (d,
J = 8.6 Hz, 2H, Ar), 0.35 (s, 18H, SiMe3) ppm. 13C
NMR (CDCl3): d 140.02, 134.71, 133.36, 133.07, 129.84,
129.73, 127.59, 124.09, 122.30, 114.82 (Ar), 109.10,
105.63 (C„C), 0.00 (SiMe3) ppm. FAB-MS: m/z 470
[M+]. Anal. Calc. for C28H28NClSi2: C, 71.53; H, 6.00;
N, 2.98. Found: C, 71.35; H, 5.84; N, 3.00%.
nyl-9-(p-methoxyphenyl)carbazole
(480.0 mg). IR (CH2Cl2): m(C„C) 2107, m(C„CH)
3301 cmꢀ1 1H NMR (CDCl3): d 8.22 (s, br, 2H, Ar),
in
88%
yield
.
7.50 (d, J = 8.1 Hz, 2H, Ar), 7.32–7.30 (m, 2H, Ar), 7.18
(d, J = 8.1 Hz, 2H, Ar), 7.05 (d, J = 8.1 Hz, 2H, Ar),
3.86 (s, 3H, OMe), 3.07 (s, 2H, C„CH) ppm. 13C NMR
(CDCl3): d 159.00, 141.33, 130.18, 128.95, 128.17, 124.47,
122.27, 115.04, 113.41, 109.82 (Ar), 84.54, 75.72 (C„C),
55.55 (OMe) ppm. FAB-MS: m/z 321 [M+]. Anal. Calc.
for C23H15NO: C, 85.96; H, 4.70; N, 4.36. Found: C,
85.74; H, 4.60; N, 4.25%.
4.2.5. Synthesis of Ib
3,6-Bis(trimethylsilylethynyl)-9-(p-chlorophenyl)carba-
zole (789.1 mg, 1.68 mmol) was dissolved in Et2O (10 cm3)
to give a colorless solution and a catalytic amount of
K2CO3 (232.0 mg, 1.68 mmol) in MeOH (10 cm3) was
added. A milky solution was obtained after 24 h at room
temperature. The solvent was removed and the crude prod-
uct was purified by silica column chromatography eluting
with CH2Cl2 to afford a light yellow solid of 9-(p-chlor-
ophenyl)-3,6-diethynylcarbazole in 94% yield (520.0 mg).
4.2.3. Synthesis of 3,6-dibromo-9-(p-chlorophenyl)carbazole
In the absence of light, a solution of NBS (1.05 g,
5.90 mmol) in DMF (30 cm3) was slowly added dropwise
to an ice-cooled solution of 9-(p-chlorophenyl)carbazole
(0.71 g, 2.57 mmol) in DMF (30 cm3), and the mixture
was stirred for 4 h at room temperature. Ice was added
to the mixture and a white solid was precipitated. The
crude product was washed with water (3 · 15 cm3) and
recrystallized from toluene/hexane to afford 3,6-dibromo-
9-(p-chlorophenyl)carbazole (0.97 g, 87%). 1H NMR
(CDCl3): d 8.17 (s, br, 2H, Ar), 7.50 (d, J = 8.0 Hz, 2H,
Ar), 7.51–7.48 (m, 2H, Ar), 7.43 (d, J = 8.0 Hz, 2H, Ar),
7.20 (d, J = 8.0 Hz, 2H, Ar) ppm. 13C NMR (CDCl3): d
139.68, 135.30, 133.82, 130.38, 129.52, 128.23, 124.00,
123.29, 113.32, 111.26 (Ar) ppm. FAB-MS: m/z 436
[M+]. Anal. Calc. for C18H10NBr2Cl: C, 49.64; H, 2.31;
N, 3.22. Found: C, 49.45; H, 2.10; N, 3.03%.
IR (CH2Cl2): m(C„C) 2107, m(C„CH) 3301 cmꢀ1 1H
.
NMR (CDCl3): d 8.19 (s, br, 2H, Ar), 7.55–7.47 (m, 4H,
Ar), 7.39–7.36 (d, J = 8.6 Hz, 2H, Ar), 7.22–7.18 (d,
J = 8.6 Hz, 2H, Ar), 3.09 (s, 2H, C„CH) ppm. 13C
NMR (CDCl3): d 140.62, 135.01, 133.56, 130.34, 130.13,
128.05, 124.56, 122.60, 114.01, 109.62 (Ar), 84.29, 75.99
(C„C) ppm. FAB-MS: m/z 326 [M+]. Anal. Calc. for
C22H12NCl: C, 81.11; H, 3.71; N, 4.30. Found: C, 80.98;
H, 3.55; N, 4.10%.
4.3. Preparations of polymers and complexes
4.3.1. Synthesis of 1a
A mixture of trans-[PtCl2(PBu3)2] (100.9 mg, 0.15 mmol)
and 1 equivalent of Ia (48.4 mg, 0.15 mmol) was dissolved
in iPr2NH/CH2Cl2 (50 cm3, 1:1, v/v) and CuI (3.0 mg) was
subsequently added. After stirring at room temperature for
15 h, all the volatile compounds were removed under
reduced pressure. The residue was redissolved in CH2Cl2
and filtered through a short silica column using CH2Cl2
as eluent to give a yellow solution. After the removal of sol-
vent by a rotary evaporator, a yellow powder of the title
polymer was obtained in 65% yield (89.9 mg) after repre-
cipitation from a CH2Cl2/MeOH mixture. IR (CH2Cl2):
4.2.4. Synthesis of 3,6-bis(trimethylsilylethynyl)-9-(p-
chlorophenyl)carbazole
CuI (4.6 mg, 0.02 mmol), Pd(OAc)2 (4.4 mg, 0.02 mmol)
and PPh3 (13.4 mg, 0.05 mmol) were introduced to an ice-
cooled mixture of 3,6-dibromo-9-(p-chlorophenyl)carba-
i
zole (953.1 mg, 2.19 mmol) in freshly distilled Pr2NH
(50 cm3) under nitrogen.. The solution was stirred for
20 min. Me3SiC„CH (537.3 mg, 5.47 mmol) was then
added and the reaction mixture was stirred for 30 min in
an ice bath before being warmed to room temperature.
After reacting for 30 min at room temperature, the mixture
was heated to 85 ꢁC for 20 h. The solvent was evaporated
to dryness, the residue redissolved in Et2O (100 cm3) and
the solution washed with dilute HCl (2 · 100 cm3) followed
by water (2 · 100 cm3). Upon filtration through a pad of
celite, the filtrate was treated with saturated NaHCO3
(2 · 100 cm3) and water (2 · 100 cm3) and the resulting
organic solution was dried over MgSO4. The brown–yellow
1
m(C„C) 2098 cmꢀ1. H NMR (CDCl3): d 8.00 (m, 2H,
Ar), 7.45–7.43 (m, 2H, Ar), 7.34–7.32 (m, 2H, Ar), 7.17–
7.14 (m, 2H, Ar), 7.10–7.08 (m, 2H, Ar), 3.91 (s, 3H,
OMe), 2.23 (m, 12H, PCH2), 1.68 (m, 12H, PCH2CH2),
1.54–1.48 (m, 12H, CH2CH3), 0.99–0.94 (m, 18H,
CH2CH3) ppm. 13C NMR (CDCl3): d 158.54, 139.33,
130.50, 129.14, 128.31, 122.88, 122.10, 120.58, 114.89,
109.06 (Ar) 109.33, 104.74 (C„C), 55.58 (OMe), 26.42,
24.48, 23.98, 13.91 (Bu) ppm. 31P NMR (CDCl3): d 4.10

4038
L. Liu et al. / Journal of Organometallic Chemistry 691 (2006) 4028–4041
(JPt–P = 2375 Hz) ppm. Anal. Calc. for (C47H67NOP2Pt)n:
C, 61.42; H, 7.35; N, 1.52. Found: C, 61.20; H, 7.03; N,
1.35%.
136.47, 132.34, 129.83, 129.20, 127.92, 127.15, 123.29,
122.19, 121.36, 121.07, 108.87 (Ar), 110.51, 109.85
(C„C), 15.28, 8.36 (Et) ppm. 31P NMR (CDCl3): d 11.35
(JPt–P = 2602 Hz) ppm. FAB-MS: m/z 1340 [M+]. Anal.
Calc. for C58H80NClP4Pt2: C, 51.96; H, 6.01; N, 1.04.
Found: C, 51.77; H, 5.80; N, 0.93%.
4.3.2. Synthesis of 1b
A mixture of trans-[PtCl2(PBu3)2] (81.3 mg, 0.12 mmol)
and 1 equivalent of Ib (39.5 mg, 0.12 mmol) was dissolved
in iPr2NH/CH2Cl2 (50 cm3, 1:1, v/v) and CuI (3.0 mg) was
subsequently added. After stirring at room temperature for
15 h, a brown–yellow powder was obtained in 78%
(87.8 mg) after the same workup procedures as described
4.3.5. Synthesis of 3a
Au(PPh3)Cl (103.8 mg, 0.21 mmol) was dissolved in
MeOH (15 cm3), and Ia (28.1 mg, 0.09 mmol) in CH2Cl2
(5 cm3) was added. Then, 0.25 M NaOMe (1.4 cm3,
0.36 mmol) was added into the mixture, and the mixture
was allowed to stir at room temperature under nitrogen
for 2 h. The product was precipitated out and centrifuged.
The solvent was removed and the product was air-dried to
obtain the title product as a yellow solid (95.5 mg, 88%). IR
above for 1a. IR (CH2Cl2): m(C„C) 2101 cmꢀ1
.
1H
NMR (CDCl3): d 7.98 (m, 2H, Ar), 7.57–7.47 (m, 4H,
Ar), 7.34 (m, 2H, Ar), 7.22–7.19 (m, 2H, Ar), 2.24 (m,
12H, PCH2), 1.71 (m, 12H, PCH2CH2), 1.60–1.40 (m,
12H, CH2CH3), 1.01–0.92 (m, 18H, CH2CH3) ppm. 13C
NMR (CDCl3): d 138.58, 136.39, 132.48, 129.93, 129.28,
128.04, 123.25, 122.09, 121.14, 108.95 (Ar), 109.14,
105.25 (C„C), 26.54, 24.66, 24.19, 13.95 (Bu) ppm. 31P
NMR (CDCl3): d 4.20 (JPt–P = 2368 Hz) ppm. Anal. Calc.
for (C46H64NClP2Pt)n: C, 59.83; H, 6.99; N, 1.52. Found:
C, 59.55; H, 6.78; N, 1.34%.
1
(CH2Cl2): m(C„C) 2113 cmꢀ1. H NMR (CDCl3): d 8.28
(s, 2H, Ar), 7.61–7.39 (m, 36H, Ar), 7.18 (d, J = 8.4 Hz,
2H, Ar), 3.89 (s, 3H, OMe) ppm. 13C NMR (CDCl3): d
158.68, 140.38, 134.29, 134.08, 131.38, 130.50, 130.14,
129.80, 129.33, 128.88, 128.27, 124.38, 122.62, 114.91
(Ar), 115.97, 109.28 (C„C) 55.60 (OMe) ppm. 31P NMR
(CDCl3): d 43.91 ppm. FAB-MS: m/z 1238 [M+]. Anal.
Calc. for C59H43NOP2Au2: C, 57.25; H, 3.50; N, 1.13.
Found: C, 57.01; H, 3.26; N, 0.99%.
4.3.3. Synthesis of 2a
Treatment of Ia (34.0 mg, 0.11 mmol) with two equiva-
lents of trans-[PtPh(Cl)(PEt3)2] (115.0 mg, 0.22 mmol) at
room temperature for 15 h, in the presence of CuI
(3.0 mg), in iPr2NH/CH2Cl2 (30 cm3, 1:1, v/v) gave the title
complex as a yellow solid in 63% yield (89.0 mg) after puri-
fication on silica TLC plates using hexane/CH2Cl2 (40:60,
4.3.6. Synthesis of 3b
Au(PPh3)Cl (105.3 mg, 0.21 mmol) was dissolved in
MeOH (15 cm3), and Ib (32.5 mg, 0.09 mmol) in CH2Cl2
(5 cm3) was added. Subsequently, 0.25 M NaOMe
(1.4 cm3, 0.36 mmol) was added into the mixture, and the
mixture was allowed to stir at room temperature under
nitrogen for 2 h. The product was precipitated out and cen-
trifuged. The solvent was removed and the product was air-
dried to obtain a yellow solid (108.1 mg, 95%). IR
v/v) as eluent. IR (CH2Cl2): m(C„C) 2095 cmꢀ1 1H
.
NMR (CDCl3): d 8.03 (s, 2H, Ar), 7.44–7.40 (m, 3H,
Ar), 7.38–7.34 (m, 5H, Ar), 7.16–7.14 (m, 2H, Ar), 7.09–
7.07 (m, 2H, Ar), 6.97 (t, J = 7.4 Hz, 4H, Ar), 6.82 (t,
J = 7.2 Hz, 2H, Ar), 3.90 (s, 3H, OMe), 1.85–1.77 (m,
24H, PCH2CH3), 1.17–1.06 (m, 36H, PCH2CH3) ppm.
13C NMR (CDCl3): d 158.47, 156.78, 139.26, 130.57,
129.09, 128.22, 127.20, 122.93, 122.21, 121.07, 120.76,
115.02, 114.85, 109.02 (Ar) 110.75, 109.23 (C„C), 55.55
(OMe), 15.09, 8.05 (Et) ppm. 31P NMR (CDCl3): d 10.87
(JPt–P = 2643 Hz) ppm. FAB-MS: m/z 1336 [M+]. Anal.
Calc. for C59H83NOP4Pt2: C, 53.03; H, 6.26; N, 1.05.
Found: C, 52.88; H, 6.03; N, 0.96%.
1
(CH2Cl2): m(C„C) 2113 cmꢀ1. H NMR (CDCl3): d 8.25
(s, 2H, Ar), 8.25–7.40 (m, 36H, Ar), 7.21 (d, J = 8.1 Hz,
2H, Ar) ppm. 13C NMR (CDCl3): d 139.71, 135.83,
134.33, 134.12, 132.93, 131.41, 130.73, 130.16, 129.94,
129.09, 128.92, 128.17, 124.50, 123.02 (Ar) 116.62, 109.16
(C„C) ppm. 31P NMR (CDCl3): d 43.86 ppm. FAB-MS:
m/z 1242 [M+]. Anal. Calc. for C58H40ClNP2Au2: C,
56.08; H, 3.25; N, 1.13. Found: C, 55.86; H, 3.01; N, 1.10%.
4.3.4. Synthesis of 2b
4.3.7. Synthesis of 4a
Treatment of Ib (37.0 mg, 0.11 mmol) with two equiva-
lents of trans-[PtPh(Cl)(PEt3)2] (123.6 mg, 0.22 mmol) at
room temperature for 15 h, in the presence of CuI (3 mg),
The di-yne Ia (46.9 mg, 0.15 mmol) in MeOH (10 cm3)
was first combined with MeHgCl (88.5 mg, 0.35 mmol) in
MeOH (10 cm3) and 0.20 M basic MeOH (2.9 cm3,
0.58 mmol) was subsequently added to give a pale-yellow
suspension. The solvents were then decanted and a light-
yellow solid of the title compound was washed with MeOH
(2 · 20 cm3) and air-dried (90.8 mg, 83%). IR (CH2Cl2):
i
in Pr2NH/CH2Cl2 (30 mL, 1:1, v/v) gave the title complex
as a yellow solid in 55% yield (79.2 mg) after purification
on silica TLC plates using hexane/CH2Cl2 (40:60, v/v) as
eluent. IR (CH2Cl2): m(C„C) 2092 cmꢀ1
.
1H NMR
(CDCl3): d 8.01 (s, 2H, Ar), 7.55–7.45 (m, 6H, Ar), 7.38–
7.34 (m, 4H, Ar), 7.19 (d, J = 8.4 Hz, 2H, Ar), 6.97 (t,
J = 7.3 Hz, 4H, Ar), 6.81 (t, J = 7.0 Hz, 2H, Ar) 1.84–
1.77 (m, 24H, PCH2CH3), 1.19–1.04 (m, 36H, PCH2CH3)
ppm. 13C NMR (CDCl3): d 156.42, 139.14, 138.41,
m(C„C) 2131 cmꢀ1 1H NMR (CDCl3): d 8.21 (s, 2H,
.
Ar), 7.52 (m, 2H, Ar), 7.42 (d, J = 8.9 Hz, 2H, Ar), 7.22
(d, J = 8.6 Hz, 2H, Ar), 7.11 (d, J = 8.9 Hz, 2H, Ar),
3.91 (s, 3H, OMe), 0.70 (s, J = 146.1 Hz, 6H, MeHg)
ppm. 13C NMR (CDCl3): d 159.05, 141.09, 140.80,

L. Liu et al. / Journal of Organometallic Chemistry 691 (2006) 4028–4041
4039
Table 7
Summary of crystal structure data for 2a, 3a and 4b
2a
3a
4b
Empirical formula
Molecular weight
Crystal size (mm)
Crystal system
C59H83NOP4Pt2
1336.32
0.30 · 0.24 · 0.10
Triclinic
C59H43NOP2Au
1237.82
0.28 · 0.20 · 0.18
Monoclinic
P21/c
20.334(10)
16.745(8)
14.982(7)
C24H16NClHg2
755.01
0.25 · 0.20 · 0.10
Monoclinic
P2/c
16.3623(12)
16.7364(12)
7.5600(6)
90
97.871(2)
90
ꢀ
Space group
P1
˚
a (A)
18.0068(11)
18.2384(10)
19.6550(12)
99.5020(10)
90.8620(10)
103.3270(10)
6185.5(6)
4.657
˚
b (A)
˚
c (A)
a (ꢁ)
b (ꢁ)
c (ꢁ)
90
111.041(9)
90
4761(4)
6.266
1.727
4
3
˚
U (A )
2050.8(3)
15.094
2.445
l (Mo Ka) (mmꢀ1
)
Dcalc (g cmꢀ3
Z
)
1.435
4
4
F(000)
2672
2400
1376
h Range (ꢁ)
1.70–25.00
31,212
21,427
1.90–25.00
23,286
8366
0.0355
1.75–25.00
10,104
3607
Reflections collected
Unique reflections
Rint
0.0501
0.0883
Observed reflections [I > 2r(I)]
Number of parameters
R1, wR2[I > 2r(I)]
R1, wR2 (all data)
Goodness-of-fit on F2
9961
1207
6752
586
0.0341, 0.0892
0.0481, 0.0982
2056
259
0.0546, 0.1174
0.1189, 0.1435
0.999
0.872 to ꢀ0.878
0.0630, 0.1314
0.1547, 0.1718
0.975
1.822 to ꢀ2.317 (close to Pt)
1.024
ꢀ3
˚
Residual extrema in final difference map (e A
)
2.204 to ꢀ1.154 (close to Au)
130.32, 129.32, 128.33, 124.37, 122.55, 115.11, 114.47 (Ar),
109.84, 106.36 (C„C), 55.65 (OMe), 7.29 (MeHg) ppm.
FAB-MS: m/z 751 [M+]. Anal. Calc. for C25H19NOHg2:
C, 40.00; H, 2.55; N, 1.87. Found: C, 39.88; H, 2.30; N,
1.58%.
of the analyses are listed in Table 7. Geometric and inten-
sity data were collected at room temperature on a Bruker
Axs Smart 1000 CCD area detector using graphite-mono-
˚
chromated Mo Ka radiation (k = 0.71073 A). The col-
lected frames were processed with the software SAINT [34],
and an absorption correction was applied (SADABS) [35] to
the collected reflections. The structure was solved by the
Patterson or direct methods (SHELXTL) [36] in conjunction
with standard difference Fourier techniques and subse-
quently refined by full-matrix least-squares analyses on
F2. All non-hydrogen atoms were assigned with anisotropic
displacement parameters.
4.3.8. Synthesis of 4b
The ligand Ib (44.8 mg, 0.14 mmol) in MeOH (10 cm3)
was first combined with MeHgCl (82.9 mg, 0.33 mmol) in
MeOH (10 cm3) and 0.20 M basic MeOH (2.8 cm3,
0.56 mmol) was subsequently added to give a pale-yellow
suspension. The solvents were then decanted and a pale yel-
low solid of the title compound was washed with MeOH
(2 · 20 cm3) and air-dried (92.1 mg, 89%). IR (CH2Cl2):
Acknowledgements
m(C„C) 2134 cmꢀ1 1H NMR (CDCl3): d 8.22 (s, 2H,
.
Ar), 7.61 (m, 2H, Ar), 7.57 (m, 2H, Ar), 7.49 (d,
J = 8.6 Hz, 2H, Ar), 7.24 (d, J = 8.9 Hz, 2H, Ar), 0.72 (s,
J = 145.3 Hz, 6H, MeHg) ppm. 13C NMR (CDCl3): d
141.06, 140.29, 135.21, 133.44, 130.39, 130.10, 128.12,
124.34, 122.77, 114.96 (Ar), 109.57, 105.91 (C„C), 7.17
(MeHg) ppm. FAB-MS: m/z 755 [M+]. Anal. Calc. for
C24H16NClHg2: C, 38.18; H, 2.14; N, 1.86. Found: C,
37.96; H, 2.02; N, 1.55%.
Financial support from a CERG Grant from the Hong
Kong Research Grants Council of the Hong Kong SAR,
P.R. China (Project No. HKBU2022/03P) and Hong Kong
Baptist University is gratefully acknowledged.
Appendix A. Supplementary material
Crystallographic data (comprising hydrogen atom
coordinates, thermal parameters and full tables of bond
lengths and angles) for the structural analysis has been
deposited with the Cambridge Crystallographic Centre
(Deposition Nos. 602241–602243). Copies of this informa-
tion may be obtained free of charge from The Director,
CCDC, 12 Union Road, Cambridge CB2 1EZ, UK (Fax:
+ 44 1223 336 033; e-mail: deposit@ccdc.cam.ac.uk or
5. Crystallography
Single crystals of 2a, 3a and 4b suitable for X-ray dif-
fraction work were obtained by slow evaporation of their
respective solutions in CH2Cl2/hexane at room tempera-
ture. Crystal data, data collection parameters and results

4040
L. Liu et al. / Journal of Organometallic Chemistry 691 (2006) 4028–4041
(b) W.-Y. Wong, L. Liu, S.-Y. Poon, A.W.-M. Lee, K.-W. Cheah,
J.-X. Shi, Macromolecules 37 (2004) 4496.
www: http://www.ccdc.cam.ac.uk). Supplementary data
associated with this article can be found, in the online ver-
sion, at doi:10.1016/j.jorganchem.2006.06.006.
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