Organometallic complexes for nonlinear optics. 37: Synthesis and third-order nonlinear optical properties of a hexarutheniumtriplatinum dendrimer

Article abstract of DOI:10.1016/j.poly.2006.05.007

The complexes trans-[Pt(C{triple bond, long}CC₆H₄-4-C{triple bond, long}CPh)Cl(PMe₂Ph)₂] (1), 1,3,5-C₆H₃{C{triple bond, long}CC₆H₄-4-C{triple bond, long}C-trans-[PtCl(PMe₂Ph)₂]}₃ (2) and 1,3,5-C₆H₃(C{triple bond, long}CC₆H₄-4-C{triple bond, long}C-trans-[Pt(PMe₂Ph)₂]C{triple bond, long}C-4-C₆H₄C{triple bond, long}C-3,5-C₆H₃-{C{triple bond, long}C-trans-[Ru(C{triple bond, long}CPh)(dppe)₂]}₂)₃ (3) have been synthesized and the identity of 1 confirmed by a single-crystal X-ray diffraction study. The optical limiting merit of 1 and 2 has been assessed at 523 nm employing 40 ns pulses; the effective absorption cross-section for 1 is low, while that of 2 is larger, but the complex is susceptible to photo-damage. The third-order nonlinearity of the Ru₆Pt₃ dendrimer 3 has been examined at 800 nm using 150 fs pulses; it is larger than that of a related Ru₆ dendrimer, but smaller than that of a Ru₉ dendrimer under the same conditions, suggesting that increasing metal content and electron richness is correlated to increased nonlinearity in these complexes.

Full text of DOI:10.1016/j.poly.2006.05.007

Polyhedron 26 (2007) 284–289
www.elsevier.com/locate/poly
Organometallic complexes for nonlinear optics. 37: Synthesis
and third-order nonlinear optical properties of
a hexarutheniumtriplatinum dendrimer
a
a
a,
b
Clem E. Powell , Marie P. Cifuentes , Mark G. Humphrey *, Anthony C. Willis ,
Joseph P. Morrall a,c, Marek Samoc
c
a
Department of Chemistry, Australian National University, Canberra, ACT 0200, Australia
Research School of Chemistry, Australian National University, Canberra, ACT 0200, Australia
Laser Physics Centre, Research School of Physical Sciences and Engineering, Australian National University, Canberra, ACT 0200, Australia
b
c
Received 22 March 2006; accepted 8 May 2006
Available online 16 May 2006
Contribution to the Special Issue ‘‘Modern Inorganic Chemistry in Australia and New Zealand’’.
Abstract
The complexes trans-[Pt(C„CC6H4-4-C„CPh)Cl(PMe2Ph)2] (1), 1,3,5-C6H3{C„CC6H4-4-C„C-trans-[PtCl(PMe2Ph)2]}3 (2) and
1,3,5-C6H3(C„CC6H4-4-C„C-trans-[Pt(PMe2Ph)2]C„C-4-C6H4C„C-3,5-C6H3-{C„C-trans-[Ru(C„CPh)(dppe)2]}2)3 (3) have been
synthesized and the identity of 1 confirmed by a single-crystal X-ray diffraction study. The optical limiting merit of 1 and 2 has been
assessed at 523 nm employing 40 ns pulses; the effective absorption cross-section for 1 is low, while that of 2 is larger, but the complex
is susceptible to photo-damage. The third-order nonlinearity of the Ru6Pt3 dendrimer 3 has been examined at 800 nm using 150 fs pulses;
it is larger than that of a related Ru6 dendrimer, but smaller than that of a Ru9 dendrimer under the same conditions, suggesting that
increasing metal content and electron richness is correlated to increased nonlinearity in these complexes.
ꢀ 2006 Elsevier Ltd. All rights reserved.
Keywords: Ruthenium; Platinum; Dendrimer; Nonlinear optics; Optical limiting
1. Introduction
We report herein the synthesis of a mixed-metal arylalky-
nyl dendrimer incorporating both ruthenium and platinum,
together with an assessment of its third-order nonlinear
optical (NLO) properties.
Organotransition metal dendrimers have attracted enor-
mous interest over the past few years [1]. Although most
examples are peripherally-metallated organic dendrimers,
several dendrimers with metals in each generation and an
arylethynyl-derived framework have been reported. The
focus of our studies has been ruthenium-containing aryl-
alkynyl dendrimers [2–10], while other groups have
reported related platinum-containing examples [11–15].
2. Experimental
2.1. General conditions and reagents
All reactions were performed under a nitrogen atmo-
sphere with the use of Schlenk techniques. Dichlorometh-
ane was dried by distilling over calcium hydride; other
solvents were used as received. Chromatography was per-
formed on ungraded basic alumina.
*
Corresponding author. Tel.: +61 2 6125 2927; fax: +61 2 6125 0760.
E-mail address: Mark.Humphrey@anu.edu.au (M.G. Humphrey).
0277-5387/$ - see front matter ꢀ 2006 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2006.05.007

C.E. Powell et al. / Polyhedron 26 (2007) 284–289
285
The following were prepared by literature procedures:
HC„CC6H4-4-C„CPh [16], 1,3,5-C6H3(C„CC6H4-4-
C„CH)3 [9], 1,3-{trans-[(dppe)2(PhC„C)RuC„C]}2-5-
(HC„C-4-C6H4C„C)C6H3 [6]. PtCl2(PMe2Ph)2 was a gift
from Dr E. Wenger and Prof. A.F. Hill, RSC, Australian
National University. CuCl (J.T. Baker) was used as
received.
(fragment, relative intensity): 1970 ([M]+, 2), 471
([Pt(PMe2Ph)]+, 40).
2.2.3. 1,3,5-C6H3(C„CC6H4-4-C„C-trans-
[Pt(PMe2Ph)2]C„C-4-C6H4C„C-3,5-C6H3-{C„C-
trans-[Ru(C„CPh)(dppe)2]}2)3 (3)
A
solution of
2
(21 mg, 11 lmol), 1,3-{trans-
Microanalyses were carried out at the Australian
National University. UV–Vis spectra of solutions in tetra-
hydrofuran in 1 cm cells were recorded using a Cary 5
spectrophotometer. Infrared spectra were recorded as
dichloromethane solutions using a Perkin–Elmer System
2000 FT-IR. 1H (300 MHz) and 31P NMR (121 MHz)
spectra were recorded using a Varian Gemini-300 FT
NMR spectrometer and are referenced to residual chloro-
form (7.24 ppm) or external H3PO4 (0.0 ppm), respec-
tively. Fast atom bombardment mass spectra (FAB MS)
were recorded on a VG ZAB-2SEQ hybrid sector (BEqQ)
MS instrument (30 kV Cs+ ions, current 1 mA, accelerat-
ing potential 8 kV, matrix 3-nitrobenzyl alcohol) at the
ANU.
[(dppe)2(PhC„C)RuC„C]}2-5-(HC„C-4-C6H4C„C)C6H3
(73 mg, 0.034 mmol) and CuCl (15 mg, 0.15 mmol) in
CH2Cl2 (20 mL) and NEt3 (5 mL) was stirred for 19 h.
The reaction mixture was passed through a short pad of
alumina with CH2Cl2 as eluent, and the eluate was taken
to dryness under reduced pressure. The residue was puri-
fied by vapour diffusion of MeOH into a solution in
CH2Cl2 to afford a yellow powder (53 mg, 56 %). Anal.
Calc. for C504H420P30Pt3Ru6: C, 70.41; H, 4.92. Found:
C, 69.51; H, 5.02%. IR: m(C„CPt) 2101 cmꢀ1, m(C„CRu)
2060 cmꢀ1. UV–Vis: k 357 nm, e 52300 Mꢀ1 cmꢀ1 1H
.
NMR: d 2.13 (36 H, t, 4 Hz, Me), 2.68 (48 H, m, CH2),
6.67–7.90 (336 H, m, phenyl). 31P NMR: d ꢀ11.62 (6 P, s,
JPtP: 2380 Hz), 54.25 (24 P, s). FAB MS; m/z (fragment,
relative intensity): 898 ([Ru(dppe)2]+, 55), 471
([Pt(PMe2Ph)2]+, 35).
2.2. Syntheses
2.2.1. trans-[Pt(C„CC6H4-4-C„CPh)Cl(PMe2Ph)2]
(1)
2.3. X-ray structural study of 1
A solution of cis-[PtCl2(PMe2Ph)2] (45 mg, 0.083 mmol),
HC„CC6H4-4-C„CPh (8.8 mg, 0.044 mmol) and CuCl
(6.6 mg, 0.067 mmol) in CH2Cl2 (10 mL) and NEt3
(10 mL) was stirred for 17 h. The reaction mixture was
passed through a short pad of alumina with CH2Cl2, and
the eluate was taken to dryness under reduced pressure.
Diffusion of MeOH into a CH2CH2 solution of the residue
afforded yellow needles (28 mg, 90%). Anal. Calc. for
C32H31ClP2Pt: C, 54.28; H, 4.41. Found: C, 54.21; H,
3.82%. IR: m(C„C) 2119 cmꢀ1. UV–Vis: k 342 nm, e 33
A suitable crystal of 1 was obtained by slow diffusion of
hexane into a dichloromethane solution. A single crystal
was mounted on a fine glass capillary, and data collected
on a Nonius KappaCCD diffractometer using graphite-
˚
monochromated Mo Ka radiation (k = 0.71073 A). The
unit cell parameters were obtained by least-squares refine-
ment [17] of 31726 reflections with 3 6 h 6 27ꢁ. The
reduced data were corrected for absorption using numeri-
cal methods [18] implemented from within maXus [19];
equivalent reflections were merged. The structure was
solved by heavy atom methods [20], and refined using the
software package CRYSTALS [21].
600 Mꢀ1 cmꢀ1 1H NMR: d 1.93 (12H, t, 4 Hz, Me),
.
6.98–7.81 (19H, m, phenyl). 31P NMR: d ꢀ6.84 (s, JPtP
:
2396 Hz). FAB MS; m/z (fragment, relative intensity):
708 ([M]+, 100), 672 ([M]+ꢀCl, 20), 471 ([Pt(PMe2Ph)]+,
100).
Crystal/refinement data: C32H31ClP2Pt, M = 708.09.
˚
Triclinic, space group P-1, a = 5.9924(1) A, b =
˚
˚
9.6522(1) A, c = 25.7727(3) A, a = 91.905(1)ꢁ, b = 95.940
3
˚
(1)ꢁ, c = 105.910(1)ꢁ, V = 1422.93(3) A . Dc (Z = 2) =
2.2.2. 1,3,5-C6H3{C„CC6H4-4-C„C-trans-
[PtCl(PMe2Ph)2]}3 (2)
1.653 g cmꢀ3. lMo = 5.156 mmꢀ1; specimen: 0.48 · 0.34 ·
0.21 mm; Tmin/max = 0.23/0.45. 2hmax = 55ꢁ; Ntotal = 28704
(CCD diffractometer, monochromatic Mo Ka radiation,
A solution of cis-[PtCl2(PMe2Ph)2] (48 mg, 0.089 mmol),
1,3,5-C6H3(C„CC6H4-4-C„CH)3 (7.4 mg, 0.016 mmol)
and CuCl (15 mg, 0.15 mmol) in CH2Cl2 (15 mL) and
NEt3 (10 mL) was stirred for 17 h. The reaction mixture
was passed through a short pad of alumina with CH2Cl2
as eluent, and the eluate was taken to dryness under
reduced pressure. The residue was purified by solvent diffu-
sion of MeOH into a CH2Cl2 solution to afford a pale yel-
low powder (27 mg, 83%). Anal. Calc. for C84H81Cl3P6Pt3:
C, 51.27; H, 4.15. Found: C, 51.01; H, 4.23%. IR: m(C„C)
˚
k = 0.71073 A; T 200 K) merging to N = 6513 unique
(Rint = 0.04), No = 5067 (I > 3r(I)) refining to R = 0.020,
Rw = 0.020. The crystallographic asymmetric unit consists
of one [Pt(C16H9)(C8H11P)2Cl] molecule. The largest peaks
in the final difference electron density map were located near
the Pt atom.
2.4. Z-scan measurements
2117 cmꢀ1. UV–Vis: k 345 nm, e 123000 Mꢀ1 cmꢀ1
.
1H
Z-scan measurements [29] were performed using a
femtosecond laser system based on a Coherent Mira-
900D Ti–sapphire oscillator and including a chirped pulse
NMR: d 1.94 (36 H, t, 4 Hz, Me), 6.98–7.84 (45 H, m, phe-
nyl). 31P NMR: d ꢀ6.84 (s, JPtP: 2400 Hz). FAB MS; m/z

286
C.E. Powell et al. / Polyhedron 26 (2007) 284–289
Ti–sapphire amplifier operating at a repetition rate of
30 Hz. This system operated at a wavelength of 800 nm
and provided ca. 150 fs FWHM pulses. The Z-scan set-
up used lenses with the focal lengths suitable for creating
sized by reaction of cis-[PtCl2(PMe2Ph)2] with the relevant
alkynyl ligand in the presence of a CuCl catalyst (Scheme
1). There is no inherent means of avoiding generation of
the bis-alkynyl complex – to minimize its formation, an
excess of cis-[PtCl2(PMe2Ph)2] was added, no trace of the
bis-alkynyl product being observed in the 31P NMR spec-
trum. The products were characterized by 1H and 31P
NMR, UV–Vis, IR, FAB mass spectrometry and (in the
case of the linear analogue) a single-crystal X-ray diffrac-
tion study.
Selected bond distances and angles are listed in Table 1,
and an ORTEP plot is displayed in Fig. 1. The crystallo-
graphic asymmetric unit consists of one molecule of 1.
The complex shows square-planar geometry around the
metal center, with only small deviations from the idealized
geometry. An example of an octupolar platinum–alkynyl
complex incorporating a C„CC6H4-4-C„CPh motif,
1,3,5-[Cl(PEt3)2PtC„CC6H4-4-C„C]3C6H3, has been
reported previously and structurally characterized [22].
Reported bond lengths for this octupolar complex [Pt–Cl:
focal spots with the 1/e2 radius, w0, being in the range
pw20
k
40–65 lm. This resulted in the Rayleigh lengths, zR ¼
,
being greater than 3 mm; the measurements of tetrahydro-
furan solutions in 1 mm thick glass cells with ca. 1 mm
thick glass walls could therefore be treated in the thin sam-
ple approximation. All measurements were calibrated
against Z-scans taken on the pure solvent and on silica
and glass plates of thicknesses in the range 1–2.5 mm; the
value n2 = 3 · 10ꢀ16 cm2 Wꢀ1 was adopted for silica non-
linear index. Nonlinear phase shifts for the measured sam-
ples were in the range 0.5–1.0 rad, corresponding to peak
intensities of the order of 100 GW cmꢀ1
.
2.5. Optical limiting measurements
The measurements were performed using the Z-scan
technique at 523 nm, with about 5 lJ, 40 ns pulses from a
frequency-doubled Q-switched Nd:YLF diode-pumped
laser. Solutions of both compounds were placed in 1 mm
path length glass cells. The open-aperture Z-scans were
converted into transmission–fluence plots using an assump-
tion of Gaussian beam propagation and the spot size deter-
mination made on the basis of numerical fitting of the
closed-aperture Z-scan obtained simultaneously with the
open-aperture measurement (the signal in the closed-aper-
ture Z-scan was due to thermal nonlinearity of the
solutions). The data were analyzed assuming that excited-
state absorption is responsible for the effect.
˚
˚
˚
2.358(6) A, Pt–C: 1.95(2) A, Pt–P: 2.276(9)–2.297(8) A
˚
and C„C: 1.14(3) A] are similar to those observed with 1.
Table 1
˚
Selected bond distances (A) and angles (ꢁ) for 1
Pt1–C1
Pt1–P1
C1–C2
C2–C3
P1–C17
P2–C19
P1–C21
1.953(3)
2.3051(8)
1.200(4)
1.441(4)
1.813(3)
1.810(3)
1.819(3)
Pt1–Cl1
Pt1–P2
2.3588(8)
2.3059(8)
1.200(5)
1.432(4)
1.807(3)
1.817(3)
1.817(3)
C9–C10
C10–C11
P1–C18
P2–C20
P2–C27
3. Results and discussion
Cl–Pt1–P1
P1–Pt1–P2
Pt1–C1–C2
C6–C9–C10
87.70(3)
177.16(3)
178.7(3)
178.7(4)
Cl1–Pt1–P2
Cl1–Pt1–C1
C1–C2–C3
91.52(3)
177.25(9)
177.4(3)
177.7(4)
The bis(phosphine)platinum-containing core of the den-
drimer (2), together with a linear analogue (1), was synthe-
C9–C10–C11
PMe2Ph
cis-[PtCl2(PMe2Ph)2]
H
Pt Cl
CuCl
CH2Cl2
NEt3
PMe2Ph
1
Cl
Pt
PhMe2P
PMe2Ph
H
cis-[PtCl2(PMe2Ph)2]
CuCl
CH2Cl2
NEt3
PMe2Ph
Cl
PhMe2P
H
Pt
H
Pt
2
Cl
PMe2Ph
Scheme 1. Syntheses of 1 and 2.
PhMe2P

C.E. Powell et al. / Polyhedron 26 (2007) 284–289
287
54.4 ppm, consistent with a bis-alkynyl ruthenium unit; the
integral of the resonances is 1:2, as expected. The IR spectra
of the platinum-containing complexes 1 and 2 each show a
band at approximately 2119 cmꢀ1, which is consistent with
similar platinum complexes: trans-[Pt(C„CPh)2(PMe2Ph)2]-
2106 cmꢀ1 [24], trans-[Pt(C„CCH2OH)2(PMe2Ph)2] 2120
cmꢀ1, trans-[Pt(C„CCH2CH2OH)2(PMe2Ph)2] 2110 cmꢀ1
and trans-[Pt(C„CCH2OPh)2(PMe2Ph)2] 2115 cmꢀ1 [25].
The mixed platinum/ruthenium dendrimer 3 contains two
bands at 2060 and 2101 cmꢀ1, assigned to the ruthenium-
and platinum-bound alkynyl groups, respectively.
Measurement of the third-order molecular nonlinearity
of 3 was performed using the Z-scan technique at 800 nm;
results are presented in Table 2, together with previously-
reported data for related ruthenium-containing dendrimers.
The mixed-metal dendrimer, 3, possesses a jc800j of
7200 2900 · 10ꢀ36 esu. This is substantially higher than
that of the phenylalkynyl-containing dendrimer 1,3,5-{3,5-
(trans-[(dppe)2(PhC„C)RuC„C])2C6H3C„CC6H4-4-C„
C}3C6H3 (1600 2400 · 10ꢀ36 esu) [26], but lower than
that of 1,3,5-C6H3(C„CC6H4-4-C„C-trans-[Ru(dppe)2]-
C„C-3,5-C6H3-{C„CC6H4-4-C„C-trans-[Ru(C„CPh)-
(dppe)2]}2)3 (20700 2000 · 10ꢀ36 esu) [3]. Increasing the
metal loading (proceeding from the Ru6 to Ru6M3 dendri-
mers, M = Ru, Pt) and increasing electron richness (pro-
ceeding from Ru6Pt3, with a mixture of 18 and 16 valence
electron metals, to Ru9, with 18 electron metal centers only)
both result in an increase in jc800j.
Fig. 1. Thermal ellipsoid diagram of trans-[Pt(C„CC6H4-4-
C„CPh)Cl(PMe2Ph)2] with labeling of selected atoms. Ellipsoids show
30% probability levels. H atoms have been omitted for clarity.
The triplatinum dendritic core, 2, was reacted with the
wedge, 1,3-{trans-[(dppe)2(PhC„C)RuC„C]}2-5-(HC„
C-4-C6H4C„C)C6H3, in the presence of CuCl to give the
mixed-metal dendrimer complex, 1,3,5-C6H3(C„CC6H4-
4-C„C-trans-[Pt(PMe2Ph)2]C„C-4-C6H4C„C-3,5-C6H3-
{C„C-trans-[Ru(C„CPh)(dppe)2]}2)3 (3) (Scheme 2). The
1
dendrimer was characterized by H and 31P NMR, UV–
Vis, IR, and FAB mass spectrometry.
Examination of the 31P NMR spectroscopic data for 1, 2
and 3 reveals a 31P chemical shift of ꢀ6.8 ppm in the case of
complexes containing a chloro-ligand (1 and 2), which moves
to ꢀ11.6 ppm upon replacement of the chloro ligand by an
alkynyl group on conversion of 2 to 3. These figures are con-
sistent with literature values for trans-[Pt(C„CPh)-
Cl(PMe2Ph)2] and trans-[Pt(C„CPh)2(PMe2Ph)2], which
have 31P NMR spectral shifts of ꢀ7.5 and ꢀ12.4 ppm,
respectively [23]. Complex 3 also contains a resonance at
Platinum-alkynyl complexes possess interesting optical
properties [22,26–28]. Of particular relevance to the current
studies, trans-[Pt(C„CC6H4-4-C„CPh)2(PBu3)2] has been
shown to act as a broadband optical limiter [28]. In view of
the close structural similarities between the linear platinum
complex
trans-[Pt(C„CC6H4-4-C„CPh)Cl(PMe2Ph)2]
(1), its octupolar analogue 2, and trans-[Pt(C„CC6H4-4-
Cl
PhMe2P Pt PMe2Ph
[Ru]
[Ru]
[Ru] = Ru(dppe)2
PMe2Ph
PhMe2P
Pt
CuCl
NEt3
CH2Cl2
Pt
PhMe2P
Pt PMe2Ph
Cl
Cl
PMe2Ph
PMe2Ph
2
+
PMe2Ph
Pt
PhMe2P
Pt
Ru
Ru
PMe2Ph
[Ru]
PhMe2P
[Ru]
3
[Ru]
[Ru]
H
Scheme 2. Synthesis of 3.

288
C.E. Powell et al. / Polyhedron 26 (2007) 284–289
Table 2
Experimental nonlinear optical response parameters
Complex
creal (10ꢀ36 esu)
cimag (10ꢀ36 esu)
jcj (10ꢀ36 esu)
1600 2400
7200 2900
Ref.
1,3,5-{3,5-(trans-[(dppe)2(PhC„C)RuC„C])2C6H3C„CC6H4-4-C„C}3C6H3
ꢀ1600 2400
ꢀ6700 2600
0
0
[6]
1,3,5-C6H3(C„CC6H4-4-C„C-trans-[Pt(PMe2Ph)2]C„C-4-C6H4-3,5-C6H3-
{C„C-trans-[Ru(C„CPh)(dppe)2]}2)3 (3)
ꢀ2500 1300
this work
1,3,5-C6H3(C„CC6H4-4-C„C-trans-[Ru(dppe)2]C„C-3,5-C6H3-
{4-C„CC6H4C„C-trans-[Ru(C„CPh)(dppe)2]}2)3
ꢀ5050 500
20100 2000
20700 2000
[3]
1.20E+00
1.00E+00
8.00E-01
6.00E-01
4.00E-01
2.00E-01
0.00E+00
Coupling the triplatinum core complex 2 to three equiva-
lents of the triruthenium dendron complex has afforded a
hexarutheniumtriplatinum dendrimer. The cubic optical
nonlinearity of this dendrimer is lower than that of a non-
aruthenium dendrimer that we reported previously [3], sug-
gesting that a search for organometallic dendrimers with
larger NLO coefficients should focus on those with elec-
tron-rich (18 valence electron) metal centers. The synthetic
methodology that we have employed in the current studies
is, in principle, applicable to higher generation species,
which will be the subject of a future report.
0.0001
0.001
0.01
Fluence (J/cm2)
Fig. 2. Transmission–fluence plot for 2.
0.1
1
10
Acknowledgements
We thank the Australian Research Council for support
of this work and Johnson-Matthey Technology Centre
for the generous loan of ruthenium salts. M.G.H. is an
ARC Australian Professorial Fellow. M.P.C. is an ARC
Australian Research Fellow.
C„CPh)2(PBu3)2], the optical limiting performance of 1
and 2 was examined at 523 nm.
Only poor optical limiting behavior was exhibited by 1;
the effective excited state absorption cross-section at
523 nm was determined to be no larger than 4 · 10ꢀ20 cm2.
In comparison, the effective absorption cross-section of
trans-[Pt(C„CC6H4-4-C„CPh)2(PBu3)2] is reported to be
7 · 10ꢀ17 cm2 [28]. The octupolar platinum–alkynyl com-
plex 2 shows a considerably larger effective absorption
cross-section than its linear analogue (7 · 10ꢀ19 cm2).
However, it is still significantly smaller than the effec-
tive absorption cross-section of trans-[Pt(C„CC6H4-
4-C„CPh)2(PBu3)2]. A plot of transmission versus fluence
for complex 2 is shown in Fig. 2, illustrating the drop-off
in transmission as the fluence increases. A significant prob-
lem, however, exists in photodecomposition of the sample.
The effective absorption cross-section value reported above
applies to a fresh sample. Subsequent measurements on the
same spot of the solution cell show considerably stronger
changes of transmission, consistent with the formation of
absorbing species. Similar photodecomposition is observed
for trans-[Pt(C„CC6H4-4-C„CPh)2(PBu3)2] [28].
Appendix A. Supplementary material
Final atomic positional coordinates, with estimated
standard deviations, bond lengths and angles, and aniso-
tropic thermal parameters have been deposited at the Cam-
bridge Crystallographic Data Centre and allocated the
deposition number 602009. Copies of this information
may be obtained free of charge from the Director, CCDC,
12 Union Road, Cambridge, CB2 1EZ, UK (fax: +44 1223
336 033, email: deposit@ccdc.cam.ac.uk, or www: http://
www.ccdc.cam.ac.uk). Supplementary data associated with
this article can be found, in the online version, at
doi:10.1016/j.poly.2006.05.007.
References
[1] P.A. Chase, R.J.M. Klein Gebbick, G. van Koten, J. Organomet.
Chem. 689 (2004) 4016.
[2] A.M. McDonagh, M.G. Humphrey, M. Samoc, B. Luther-Davies, S.
Houbrechts, T. Wada, H. Sasabe, A. Persoons, J. Am. Chem. Soc.
121 (1999) 1405.
4. Conclusion
[3] A.M. McDonagh, M.G. Humphrey, M. Samoc, B. Luther-Davies,
Organometallics 18 (1999) 5195.
The mono- and triplatinum complexes reported herein
are readily accessible by straightforward syntheses, but
their low optical limiting merit and lack of photostability
mitigate against potential use. The triplatinum complex is
a dendritic core in convergent dendrimer synthesis.
[4] M.P. Cifuentes, C.E. Powell, M.G. Humphrey, G.A. Heath, M.
Samoc, B. Luther-Davies, J. Phys. Chem. A 105 (2001) 9625.
[5] S.K. Hurst, M.G. Humphrey, T. Isoshima, K. Wostyn, I. Ass-
elberghs, K. Clays, A. Persoons, M. Samoc, B. Luther-Davies,
Organometallics 21 (2002) 2024.

C.E. Powell et al. / Polyhedron 26 (2007) 284–289
289
[6] S. Hurst, M.P. Cifuentes, M.G. Humphrey, Organometallics 21
(2002) 2353.
[7] S.K. Hurst, N.T. Lucas, M.G. Humphrey, T. Isoshima, K. Wostyn, I.
Asselberghs, K. Clays, A. Persoons, M. Samoc, B. Luther-Davies,
Inorg. Chim. Acta 350 (2003) 62.
[8] C.E. Powell, M.G. Humphrey, M.P. Cifuentes, J.P. Morrall, M.
Samoc, B. Luther-Davies, J. Phys. Chem. A 107 (2003) 11264.
[9] A.M. McDonagh, C.E. Powell, J.P. Morrall, M.P. Cifuentes, M.G.
Humphrey, Organometallics 22 (2003) 1402.
[10] C.E. Powell, J.P.L. Morrall, S.A. Ward, M.P. Cifuentes, E.G.A. Notaras,
M. Samoc, M.G. Humphrey, J. Am. Chem. Soc. 126 (2004) 12234.
[11] S. Leininger, P.J. Stang, S. Huang, Organometallics 17 (1998) 3981.
[12] K. Onitsuka, A. Iuchi, M. Fujimoto, S. Takahashi, Chem. Commun.
(2001) 741.
[19] S. Mackay, C.J. Gilmore, C. Edwards, M. Tremayne, N. Stewart, K.
Shankland, maXus Computer Program for the Solution and Refine-
ment of Crystal Structures, Nonius, The Netherlands, MacScience,
Japan, and The University of Glasgow, UK, 2000.
[20] P.T. Beurskens, G. Admiraal, W.P. Bosman, R.S. de Gelder, S.
Garcia-Granda, R.O. Gould, J.M.M. Smits, The DIRDIF96 Program
System. Technical Report of the Crystallographic Laboratory,
University of Nigmegen, The Netherlands, 1996.
[21] D.J. Watkin, C.K. Prout, J.R. Carruthers, P.W. Betteridge, R.I.
Cooper, CRYSTALS, issue 11, Chemical Crystallography Laboratory,
Oxford, UK, 2001.
[22] V.W.-W. Yam, C.-H. Tao, L. Zhang, K.M.-C. Wong, K.-K. Cheung,
Organometallics 20 (2001) 453.
[23] R.J. Cross, M.F. Davidson, J. Chem. Soc., Dalton Trans. (1986)
1987.
[13] K. Onitsuka, M. Fujimoto, N. Ohshiro, S. Takahashi, Angew.
Chem., Int. Ed. Engl. 38 (1999) 689.
[24] S. Yamazaki, Polyhedron 11 (1983) 1983.
[14] K. Onitsuka, S. Takahashi, Top. Curr. Chem. 228 (2003) 39.
[15] K. Onitsuka, A. Shimizu, S. Takahashi, Chem. Commun. (2003) 280.
[16] O. Lavastre, S. Cabioch, P.H. Dixneuf, J. Vohlidal, Tetrahedron 53
(1997) 7595.
[25] H.D. Empsall, B.L. Shaw, A.J. Stringer, J. Organomet. Chem. 94
(1975) 131.
[26] T.J. McKay, J.A. Bolger, J. Staromlynska, J.R. Davy, J. Chem. Phys.
108 (1998) 5537.
[17] Z. Otwinowski, W. Minor, in: C.W. Carter, R.M. Sweet (Eds.),
Methods in Enzymology, vol. 276, Academic Press, New York, USA,
1997, p. 307.
[18] P. Coppens, in: F.R. Ahmed, S.R. Hall, C.P. Huber (Eds.),
Crystallographic Computing, Munksgaard, Copenhagen, Denmark,
1970, p. 255.
[27] T.J. McKay, J. Staromlynska, P. Wilson, J.R. Davy, J. Appl. Phys. 85
(1999) 1337.
[28] J. Staromlynska, T.J. McKay, P. Wilson, J. Appl. Phys. 88 (2000)
1726.
[29] M. Sheik-Bahae, A.A. Said, T. Wei, D.J. Hagan, E.W. van Stryland,
IEEE J. Quantum Electron. 26 (1990) 760.