Organometallic complexes for nonlinear optics. Part 29. Quadratic and cubic hyperpolarizabilities of stilbenylethynyl-gold and -ruthenium complexes

Article abstract of DOI:10.1016/S0020-1693(02)01497-4

The compounds (E)-4-XC≡CC₆H₄CH=CHPh [X=SiMe₃ (1), H (2)], 1,3,5-{(E)-4-XC₆H ₄CH=CH}₃C₆H₃ [X=I (3), C≡CSiMe₃ (4), C≡CH (5)], [Au{(E)-4-C≡CC ₆H₄CH=CHPh}(L)] [L=PPh₃ (6), PMe₃ (7)], [Au(4-C≡CC₆H₄C≡CPh)(L)] [L=PPh ₃ (8), PMe₃ (9)], 1,3,5-[(Ph₃P)Au{(E)-4- C≡CC₆H₄CH=CH}]₃C₆H ₃ (10), trans-[Ru{(E)-4-C=CHC₆H₄CH=CHPh} Cl(dppm)₂]PF₆ (11), trans-[Ru{(E)-4-C≡CC ₆H₄CH=CHPh}Cl(L₂)₂] [L ₂=dppm (12), dppe (13)], [1,3,5-(trans-[(dppm)₂ClRu{(E)-4- C=CHC₆H₄CH=CH}])₃C₆H ₃](PF₆)₃ (14), 1,3,5-(trans-[(L ₂)₂ClRu{(E)-4-C≡CC₆H₄CH=CH}]) ₃C₆H₃ [L₂=dppm (15), dppe (16)] and 1,3,5-(trans-[(dppe)₂(PhC≡C)Ru{(E)-4-C≡CC ₆H₄CH=CH}])₃C₆H₃ (17) have been prepared (and the identity of 6 confirmed by a single-crystal X-ray diffraction study), and their electrochemical (Ru complexes) and nonlinear optical (NLO) properties assessed. The ruthenium complexes display reversible (12, 13, 15-17) or nonreversible (11, 14) processes attributable to Ru-centered oxidation, at potentials similar to those of previously-investigated monoruthenium alkynyl or vinylidene complexes. No evidence for intermetallic electronic communication in 14-17 is observed. Quadratic nonlinearities at 1064 and 800 nm for the octopolar stilbenyl-ruthenium complexes 14, 15 are large for compounds without strongly accepting substituents. Cubic molecular hyperpolarizabilities at 800 nm for the organic compounds and gold complexes are low. Cubic nonlinearities |γ|₈₀₀ and two-photon absorption (TPA) cross-sections σ₂ for the ruthenium complexes increase on proceeding from linear analogues 12, 13 to octopolar complexes 15, 16; the latter and 17 possess some of the largest |γ|₈₀₀ and σ₂ values for organometallics thus far. Cubic nonlinearities Im(χ⁽³⁾)/N for 13, 16, and 17 from the first application of electroabsorption (EA) spectroscopy to organometallics are also large, scaling with the number of metal atoms.

Full text of DOI:10.1016/S0020-1693(02)01497-4

Inorganica Chimica Acta 350 (2003) 62Á76
/
www.elsevier.com/locate/ica
Organometallic complexes for nonlinear optics. Part 29.
Quadratic and cubic hyperpolarizabilities of stilbenylethynylÁ
/
gold
and -ruthenium complexesꢀ
Stephanie K. Hurst a, Nigel T. Lucas a, Mark G. Humphrey a,*, Takashi Isoshima b,
Kurt Wostyn c, Inge Asselberghs c, Koen Clays c, Andre´ Persoons c, Marek Samoc d,
Barry Luther-Davies d
a Department of Chemistry, Australian National University, Canberra, ACT 0200, Australia
b RIKEN, The Institute for Physical and Chemical Research, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
c Laboratory of Chemical and Biological Dynamics, Centre for Research on Molecular Electronics and Photonics, University of Leuven,
Celestijnenlaan 200D, B-3001 Leuven, Belgium
d Australian Photonics Cooperative Research Centre, Laser Physics Centre, Research School of Physical Sciences and Engineering,
Australian National University, Canberra, ACT 0200, Australia
Received 29 April 2002; accepted 3 June 2002
Dedicated to Professor Pierre Braunstein, in recognition of his outstanding contributions to organometallic chemistry.
Abstract
The compounds (E)-4-XCꢀ
(4), CꢀCH (5)], [Au{(E)-4-Cꢀ
(9)], 1,3,5-[(Ph3P)Au{(E)-4-Cꢀ
[Ru{(E)-4-CꢀCC6H4CHꢁCHPh}Cl(L2)2] [L2ꢀ
CH}])3C6H3](PF6)3 (14), 1,3,5-(trans-[(L2)2ClRu{(E)-4-Cꢀ
[(dppe)2(PhCꢀC)Ru{(E)-4-CꢀCC6H4CHꢁCH}])3C6H3 (17) have been prepared (and the identity of 6 confirmed by a single-crystal
X-ray diffraction study), and their electrochemical (Ru complexes) and nonlinear optical (NLO) properties assessed. The ruthenium
complexes display reversible (12, 13, 15Á17) or nonreversible (11, 14) processes attributable to Ru-centered oxidation, at potentials
similar to those of previously-investigated monoruthenium alkynyl or vinylidene complexes. No evidence for intermetallic electronic
communication in 14Á17 is observed. Quadratic nonlinearities at 1064 and 800 nm for the octopolar stilbenylÁruthenium complexes
/
CC6H4CHꢁ
CC6H4CHꢁ
CC6H4CHꢁ
/
CHPh [Xꢀ
CHPh}(L)] [Lꢀ
CH}]3C6H3 (10), trans-[Ru{(E)-4-Cꢁ
dppm (12), dppe (13)], [1,3,5-(trans-[(dppm)2ClRu{(E)-4-Cꢁ
CC6H4CHꢁCH}])3C6H3 [L2ꢀdppm (15), dppe (16)] and 1,3,5-(trans-
/
SiMe3 (1), H (2)], 1,3,5-{(E)-4-XC6H4CHꢁ
PPh3 (6), PMe3 (7)], [Au(4-CꢀCC6H4Cꢀ
CHC6H4CHꢁCHPh}Cl(dppm)2]PF6 (11), trans-
CHC6H4CHꢁ
/
CH}3C6H3 [Xꢀ
/
I (3), Cꢀ
/
CSiMe3
/
/
/
/
/
/
CPh)(L)] [Lꢀ
/
PPh3 (8), PMe3
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
14, 15 are large for compounds without strongly accepting substituents. Cubic molecular hyperpolarizabilities at 800 nm for the
organic compounds and gold complexes are low. Cubic nonlinearities jgj800 and two-photon absorption (TPA) cross-sections s2 for
the ruthenium complexes increase on proceeding from linear analogues 12, 13 to octopolar complexes 15, 16; the latter and 17
possess some of the largest jgj800 and s2 values for organometallics thus far. Cubic nonlinearities Im(x(3))/N for 13, 16, and 17 from
the first application of electroabsorption (EA) spectroscopy to organometallics are also large, scaling with the number of metal
atoms.
# 2002 Elsevier Science B.V. All rights reserved.
Keywords: Ruthenium; Gold; Hyperpolarizability; Acetylide; Electrochemistry; Nonlinear optics
1. Introduction
The nonlinear optical (NLO) properties of inorganic
complexes and, particularly, organometallics have at-
ꢀ Part 28: see Ref. [1].
tracted significant interest [2Á
complexes for which NLO properties have been mea-
sured have a donorÁbridgeÁacceptor composition.
/5]. The vast majority of
* Corresponding author. Tel.: ꢁ
0760.
E-mail address: mark.humphrey@anu.edu.au (M.G. Humphrey).
/
61-2-6125 2927; fax: ꢁ61-2-6125
/
/
/
0020-1693/02/$ - see front matter # 2002 Elsevier Science B.V. All rights reserved.
doi:10.1016/S0020-1693(02)01497-4

S.K. Hurst et al. / Inorganica Chimica Acta 350 (2003) 62Á
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63
However, attention has recently turned to replacing the
classical one-dimensional dipolar composition with a
two-dimensional or three-dimensional octopolar ar-
rangement. This is because proceeding from dipolar to
octopolar geometries is a possible means of overcoming
the NLO efficiency/optical transparency trade-off and
of disfavoring centrosymmetric packing in the solid-
state, both of which have hampered the efficiency of
quadratic NLO materials. We have previously reported
the syntheses and NLO properties of octopolar and
[AuCl(PPh3)]
[15],
[AuCl(PMe3)]
[16],
1,3,5-
C6H3{CH2P(O)(OEt)2}3 [17]. NH4PF6, NaOMe,
CH, NBun4F, CuI (Aldrich),
[PdCl2(PPh3)2] (PMO), and 4-IC6H4CHO (Karl Indus-
Me3SiCꢀ
/
CH, PhCꢀ
/
tries) were used as received. [Pd(PPh3)4] was a gift from
Dr. B.L. Flynn. A synthesis of (E)-HCꢀ
CHPh (2) was reported while the current studies were
in progress [18].
/
CC6H4CHꢁ
/
EI (electron impact) mass spectra [both unit resolu-
tion and high resolution (HR)] were recorded using a
VG Autospec instrument (70 eV electron energy, 8 kV
accelerating potential) and secondary ion mass spectra
(SI MS) were recorded using a VG ZAB 2SEQ instru-
ment (30 kV Csꢁ ions, current 1 mA, accelerating
potential 8 kV, 3-nitrobenzyl alcohol matrix) at the
Research School of Chemistry, Australian National
University; peaks are reported as m/z (assignment,
relative intensity). Microanalyses were carried out at
the Research School of Chemistry, Australian National
University. Infrared spectra were recorded either as 1%
dendritic alkynylruthenium complexes [6Á8]. These
/
examples were constructed using phenylethynyl ‘spacer’
units, with several complexes having very large two-
photon absorption (TPA) cross-sections s2 [TPA is an
NLO process related to the imaginary component of the
third-order nonlinearity. TPA materials have excited
significant recent interest for applications in multi-
photon microscopy, optical limiting, and optical data
storage]. However, the E-configured alkene linker has
been shown to afford more efficient organic NLO
materials than those linked by alkyne groups [9]. We
became interested in preparing ene-linked analogues of
our yne-linked octopolar complexes. We report the
syntheses of novel two-dimensionally p-delocalized
KBr discs or dichloromethane solutions using a PerkinÁ
/
Elmer System 2000 FT IR. H and 31P NMR spectra
1
were recorded using a Varian Gemini-300 FT NMR
spectrometer and are referenced to residual chloroform
(7.24 ppm) or external 85% H3PO4 (0.0 ppm), respec-
tively. The assignments follow the numbering schemes
octopolar alkynylÁgold and -ruthenium complexes con-
/
taining E-phenylethenyl spacers, molecular quadratic
nonlinearities for the ruthenium examples at both 1064
and 800 nm employing ns and, in some instances, fs
hyper-Rayleigh scattering (HRS), respectively, molecu-
lar cubic nonlinearities jgj (including real (greal) and
imaginary (gimag) components) and TPA cross-sections
at 800 nm evaluated by fs Z-scan, and third-order NLO
susceptibilities x(3) of some of the ruthenium complexes
at approximately 450 nm determined by electroabsorp-
tion (EA) spectroscopy. Some of these results have been
reported in a preliminary fashion [1].
shown in Fig. 1. UVÁVis spectra of solutions were
/
recorded in tetrahydrofuran in 1 cm quartz cells using a
Cary 5 spectrophotometer. Electrochemical measure-
ments were recorded using a MacLab 400 interface and
MacLab potentiostat from ADInstruments. The sup-
porting electrolyte was 0.1 M (NBun4)PF6 in distilled,
deoxygenated CH2Cl2. Solutions containing approxi-
mately 1ꢂ
10ꢃ3 M complex were maintained under
/
argon. Measurements were carried out at room tem-
perature (r.t.) using platinum disc working-, Pt wire
auxiliary- and Ag/AgCl reference-electrodes, such that
the ferroceneÁ
0.56 V (peak separation around 0.09 V). Scan rates were
typically 100 mV sꢃ1
/
ferrocenium redox couple was located at
2. Experimental
.
2.1. General remarks
All reactions were performed under a nitrogen atmo-
sphere with the use of standard Schlenk techniques
unless otherwise stated. Reaction solvents dichloro-
methane and triethylamine were dried by distilling
over calcium hydride, and diethyl ether and tetrahydro-
furan were dried by distilling over sodium/benzophe-
none; other solvents were used as received. Petrol refers
2.2. (E)-4-Me3SiCꢀ
/
CC6H4CHꢁ
/
CHPh (1)
(E)-4-IC6H4CHꢁ
/
CHPh (250 mg, 0.82 mmol),
Me3SiCꢀCH (96 mg, 0.98 mmol), [PdCl2(PPh3)2] (10
/
mg) and CuI (4 mg) were stirred in triethylamine (40 ml)
for 2 h at 40 8C. The solution was filtered through a
silica plug and the solvent volume reduced under
reduced pressure to afford the white product (185 mg,
to a fraction of boiling range 60Á
phy was on silica gel (230Á400 mesh ASTM) or basic
ungraded alumina.
/
80 8C. Chromatogra-
/
82%). IR: (CH2Cl2) n(Cꢀ
/
C) 2154 cmꢃ1. UVÁ
Vis: l
/
(thf) 346 nm, o 16 800 Mꢃ1 cmꢃ1, 330 nm, o 25 200
1
The following reagents were prepared by the literature
procedures: cis-[RuCl2(dppm)2] and cis-[RuCl2(dppe)2]
Mꢃ1 cmꢃ1. H NMR: (d, 300 MHz, CDCl3); 0.24 (s,
9H, Me), 7.04 (d, JHH
16 Hz, 1H, H8), 7.15Á
276 ([M]ꢁ, 50), 261 ([Mꢃ
ꢀ
/
16 Hz, 1H, H7), 7.11 (d, JHH
7.55 (m, 9H, PhꢁC6H4). EI MS:
Me]ꢁ, 60), 179 ([Mꢃ
ꢀ
/
[10], 4-IC6H4Cꢀ
/
CSiMe3 [11], 1,3,5-(HCꢀ
/
C)3C6H3 [12],
/
/
(E)-4-IC6H4CHꢁ
/
CHPh [13], 4-HCꢀCC6H4Cꢀ
/
/CPh [14],
/
/

64
S.K. Hurst et al. / Inorganica Chimica Acta 350 (2003) 62Á76
/
Fig. 1. Numbering scheme for NMR spectral assignments for 1Á17.
/
SiMe3]ꢁ, 100). HR MS Calc. for C19H20Si m/e
276.1335. Found 276.1334.
EI MS: 762 ([M]ꢁ, 100), 636 ([Mꢃ
/
I]ꢁ, 30), 506 ([Mꢃ
/
2I]ꢁ, 10). HR MS Calc. for C30H21I3 m/e 761.8771.
Found 761.8778.
2.3. 1,3,5-{(E)-4-IC6H4CHꢁ
/
CH}3C6H3 (3)
2.4. 1,3,5-{(E)-4-Me3SiCꢀ
/
CC6H4CHꢁ
/
CH}3C6H3 (4)
4-IC6H4CHO (145 mg, 0.63 mmol), 1,3,5-
C6H3{CH2P(O)(OEt)2}3 (100 mg, 0.19 mmol) and t-
BuOK (67 mg, 0.60 mmol) were stirred in thf (30 ml)
overnight. HCl (1.0 ml, 0.5 M) was then added and the
solution passed through an alumina plug. The solvent
was reduced in volume under vacuum to afford the
1,3,5-{(E)-4-IC6H4CHꢁ
/
CH}3C6H3 (3) (200 mg, 0.26
mmol), Me3SiCꢀCH (103 mg, 1.05 mmol),
/
[PdCl2(PPh3)2] (10 mg) and CuI (4 mg) were stirred in
triethylamine (40 ml) for 2 h at 40 8C. The solution was
filtered through a silica plug and the solvent reduced in
volume under reduced pressure to afford the pale white
white product (104 mg, 72%). UVÁ
60 800 Mꢃ1 cmꢃ1, 326 nm, o 82 400 Mꢃ1 cmꢃ1. H
NMR: (d, 300 MHz, CDCl3); 7.06 (d, JHH 16 Hz, 3H,
H8), 7.13 (d, JHH 16 Hz, 3H, H7), 7.26 (d, JHH 9 Hz,
6H, H4), 7.52 (s, 3H, H10), 7.68 (d, JHH 9 Hz, 6H, H5).
/
Vis: l (thf) 340 nm, o
1
product (145 mg, 82%). IR: (CH2Cl2) n(Cꢀ
/
C) 2154
cmꢃ1. UVÁVis: l (thf) 354 nm, o 112 200 Mꢃ1 cmꢃ1
,
ꢀ
/
/
ꢀ
/
ꢀ
/
339 nm, o 136 500 Mꢃ1 cmꢃ1. 1H NMR: (d, 300 MHz,
CDCl3); 0.24 (s, 27H, Me), 7.15 (s, 6H, H7, H8), 7.49 (s,
ꢀ
/

S.K. Hurst et al. / Inorganica Chimica Acta 350 (2003) 62Á
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65
12H, H4, H5), 7.55 (s, 3H, H10). EI MS: 672 ([M]ꢁ, 35),
576 ([MꢃCꢀ
CSiMe3]ꢁ, 20). HR MS Calc. for
C45H48Si3 m/e 672.3057. Found 672.3064.
(m, 9H, Phꢁ
C6H4). 31P NMR: (d, 121 MHz, CDCl3);
/
/
/
1.7. SI MS: 533 ([Au2(PMe3)3]ꢁ, 15), 349
([Au(PMe3)2]ꢁ, 95), 273 ([Au(PMe3)]ꢁ, 100).
2.5. 1,3,5-{(E)-4-HCꢀ
/
CC6H4CHꢁ
/
CH}3C6H3 (5)
2.8. [Au(4-Cꢀ
/
CC6H4Cꢀ
/
CPh)(PPh3)] (8)
1,3,5-{(E)-4-Me3SiCꢀ
/
CC6H4CHꢁ
/
CH}3C6H3 (4) (250
[AuCl(PPh3)] (100 mg, 0.20 mmol) and 4-HCꢀ
/
mg, 0.37 mmol) and NBun4F (1.0 ml, 1 M in thf) were
stirred in dichloromethane (15 ml) for 1 h. The solvent
was removed under reduced pressure, the material was
redissolved in petrol and the solution was passed
through a silica plug eluting with petrol. The solvent
was reduced in volume under reduced pressure to afford
CC6H4CꢀCPh (45 mg, 0.22 mmol) were stirred in a
/
solution of sodium methoxide in methanol (15 ml, 0.1
M) for 16 h. Dichloromethane (15 ml) was added and
the solution passed through a silica plug. The solvent
was reduced in volume under reduced pressure to give
the yellow product (113 mg, 85%). Anal. Calc. for
C34H24AuP: C, 61.83; H, 3.66. Found: C, 61.22; H
the white product (137 mg, 81%). IR: (CH2Cl2) n(Cꢀ
/C)
2108 cmꢃ1. UVÁ
/
Vis: l (thf) 348 nm, o 90 000 Mꢃ1
4.59%. IR: (CH2Cl2) n(Cꢀ
(thf) 336 nm, o 65 000 Mꢃ1 cmꢃ1. H NMR: (d, 300
MHz, CDCl3); 7.25Á7.60 (m, 24H, Phꢁ
C6H4). 31P
/
C) 2112 cmꢃ1. UVÁ
/
Vis: l
cmꢃ1, 332 nm, o 116 800 Mꢃ1 cmꢃ1. 1H NMR: (d, 300
MHz, CDCl3); 3.13 (s, 3H, H1), 7.15 (s, 6H, H7, H8),
7.49 (s, 12H, H4, H5), 7.55 (s, 3H, H10). EI MS: 456
([M]ꢁ, 35). HR MS Calc. for C36H24 m/e 456.1879.
Found 456.1878.
1
/
/
NMR: (d, 121 MHz, CDCl3); 42.7. SI MS: 721
([Au(PPh3)2]ꢁ, 40), 660 ([M]ꢁ, 5), 459 ([Au(PPh3)]ꢁ,
100).
2.6. [Au{(E)-4-Cꢀ
/
CC6H4CHꢁ
/
CHPh}(PPh3)] (6)
2.9. [Au(4-Cꢀ
/
CC6H4Cꢀ
/
CPh)(PMe3)] (9)
[AuCl(PPh3)] (100 mg, 0.20 mmol) and (E)-4-HCꢀ
/
[AuCl(PMe3)] (100 mg, 0.32 mmol) and 4-HCꢀ
/
CC6H4CHꢁCHPh (2) (45 mg, 0.22 mmol) were stirred
/
CC6H4CꢀCPh (72 mg, 0.36 mmol) were stirred in a
/
together in a solution of sodium methoxide in methanol
(20 ml, 0.1 M) for 18 h. Dichloromethane (20 ml) was
added and the solution passed through a silica plug. The
solvent was removed under reduced pressure and the
material triturated with petrol. The solid was collected
on a sintered-glass funnel, and washed with more petrol
to yield the pale yellow product (98 mg, 73%). Anal.
Calc. for C34H26AuP: C, 61.64; H, 3.96. Found: C,
solution of sodium methoxide in methanol (20 ml, 0.1
M) for 16 h. Dichloromethane (10 ml) was added and
the solution passed through a silica plug. The solvent
was removed under reduced pressure to give the yellow
product (105 mg, 68%). Anal. Calc. for C19H18AuP: C,
48.12; H, 3.83. Found: C, 48.52; H, 4.16%. IR: (CH2Cl2)
n(Cꢀ
/
C) 2112 cmꢃ1. UVÁ
Vis: l (thf) 335 nm, o 55 000
/
Mꢃ1 cmꢃ1. H NMR: (d, 300 MHz, CDCl3); 1.56 (d,
1
61.61; H, 4.33%. IR: (CH2Cl2) n(Cꢀ
UVÁ
Vis: l (thf) 338 nm, o 16 500 Mꢃ1 cmꢃ1, 324 nm, o
25 300 Mꢃ1 cmꢃ1. H NMR: (d, 300 MHz, CDCl3);
7.06 (s, 2H, H7, H8), 7.30Á7.60 (m, 24H, Phꢁ P
C6H4). 31
/
C) 2111 cmꢃ1
.
JHP
ꢀ
/
15 Hz, 9H, Me), 7.25Á
/
7.55 (m, 9H, PhꢁC6H4).
/
/
31P NMR: (d, 121 MHz, CDCl3); 1.7. SI MS: 474
([M]ꢁ, 10), 349 ([Au(PMe3)2]ꢁ, 75), 273 ([Au(PMe3)]ꢁ,
100).
1
/
/
NMR: (d, 121 MHz, CDCl3); 42.8. SI MS: 721
([Au(PPh3)2]ꢁ, 20), 459 ([Au(PPh3)]ꢁ, 100).
2.10. 1,3,5-[(Ph3P)Au{(E)-4-Cꢀ
/
CC6H4CHꢁ
/
CH}]3C6H3 (10)
2.7. [Au{(E)-4-Cꢀ
/
CC6H4CHꢁ
/
CHPh}(PMe3)] (7)
[AuCl(PPh3)] (162 mg, 0.33 mmol) and 1,3,5-{(E)-4-
HCꢀCC6H4CHꢁCH}3C6H3 (5) (50 mg, 0.11 mmol)
[AuCl(PMe3)] (100 mg, 0.32 mmol) and (E)-4-HCꢀ
/
/
/
CC6H4CHꢁCHPh (2) (73 mg, 0.36 mmol) were stirred
/
were stirred in a solution of sodium methoxide in
methanol (0.1 M, 15 ml) for 16 h. Dichloromethane
(25 ml) was added, the solution was passed through a
silica plug and the solvent reduced in volume under
vacuum to yield the white product (158 mg, 79%). Anal.
Calc. for C90H66Au3P3: C, 59.03; H, 3.63. Found: C,
together in a solution of sodium methoxide in methanol
(20 ml, 1 M) for 18 h. Dichloromethane (10 ml) was
added and the solution passed through a silica plug. The
solvent was removed under reduced pressure and the
material triturated with petrol. The solid was collected
on a sintered-glass funnel, and washed with more petrol
to yield the white product (90 mg, 58%). Anal. Calc. for
C19H20AuP: C, 47.91; H, 4.23. Found: C, 48.53; H,
58.83; H, 4.04%. IR: (CH2Cl2) n(Cꢀ
UVÁ
Vis: l (thf) 366 nm, o 96 100 Mꢃ1 cmꢃ1, 350 nm, o
131 700 Mꢃ1 cmꢃ1. H NMR: (d, 300 MHz, CDCl3);
7.11 (s, 6H, H7, H8), 7.40Á7.60 (m, 60H, PhꢁC6H4ꢁ
C6H3). 31P NMR: (d, 121 MHz, CDCl3); 42.8. SI MS:
1834 ([Mꢁ Au(PPh3)ꢁ
3H]ꢁ, 15), 1375 ([Mꢃ 3H]ꢁ, 60),
722 ([Au(PPh3)2ꢁ
H]ꢁ, 100).
/
C) 2108 cmꢃ1
.
/
1
4.63%. IR: (CH2Cl2) n(Cꢀ
/
C) 2108 cmꢃ1. UVÁ
/
Vis: l
(thf) 339 nm, o 18 800 Mꢃ1 cmꢃ1, 323 nm, o 28 600
/
/
/
1
Mꢃ1 cmꢃ1. H NMR: (d, 300 MHz, CDCl3); 1.51 (d,
/
/
/
JHP
ꢀ
/
11 Hz, 9H, Me), 7.04 (s, 2H, H7, H8), 7.20Á
/
7.55
/

66
S.K. Hurst et al. / Inorganica Chimica Acta 350 (2003) 62Á76
/
1
2.11. trans-[Ru{(E)-4-Cꢁ
/
CHC6H4CHꢁ
/
cmꢃ1. H NMR: (d, 300 MHz, CDCl3); 2.67 (m, 8H,
PCH2CH2P), 7.10Á7.60 (m, 51H, PhꢁC6H4ꢁH7ꢁH8).
31P NMR: (d, 121 MHz, CDCl3); 50.1. SI MS: 1136
([M]ꢁ, 40), 1101 ([MꢃCl]ꢁ, 20), 957 ([Mꢃ
C6H4CHꢁ
CHPh]ꢁ, 100), 897 ([Ru(dppe)2ꢂH]ꢁ, 100).
CHPh}Cl(dppm)2]PF6 (11)
/
/
/
/
cis-[RuCl2(dppm)2] (200 mg, 0.21 mmol), (E)-4-HCꢀ
/
/
/
/
CC6H4CHꢁCHPh (3) (52 mg, 0.26 mmol) and NH4PF6
/
/
(69 mg, 0.42 mmol) were stirred together in dichlor-
omethane (25 ml) at r.t. for 24 h. Petrol (50 ml) was
added and the resulting precipitate was collected and
washed with diethyl ether (50 ml) to afford the pale
yellow product (208 mg, 78%). Anal. Calc. for
C66H56ClF6P5Ru: C, 63.19; H, 4.50. Found: C, 62.32;
2.14. [1,3,5-(trans-[(dppm)2ClRu{(E)-4-Cꢁ
/
CHC6H4CHꢁCH}])3C6H3](PF6)3 (14)
/
cis-[RuCl2(dppm)2] (185 mg, 0.20 mmol), 1,3,5-{(E)-
4-HCꢀCC6H4CHꢁCH}3C6H3 (5) (30 mg, 0.068 mmol)
/
/
H, 4.73%. IR: (KBr) n(PF) 837 cmꢃ1. UVÁ
/
Vis: l (thf)
360 nm, o 14 600 Mꢃ1 cmꢃ1. H NMR: (d, 300 MHz,
CDCl3); 3.05 (m, 1H, ꢁCH), 5.10 (m, 2H, PCH2P), 5.32
(m, 2H, PCH2P), 5.50 (d, JHH 8 Hz, 2H, H4), 6.88 (d,
JHH 8 Hz, 2H, H5), 7.10Á7.60 (m, 47H, PhꢁH7ꢁH8).
31P NMR: (d, 121 MHz, CDCl3); ꢃ
15.6. SI MS: 1109
([Mꢃ
HPF6]ꢁ, 100), 905 ([RuCl(dppm)2]ꢁ, 40), 869
([Ru(dppm)2ꢂ
H]ꢁ, 100).
and NH4PF6 (72 mg, 0.44 mmol) were added to
dichloromethane (25 ml), and the resultant mixture
stirred at r.t. for 45 h. Petrol (50 ml) was added, and
the resulting precipitate was collected and washed with
diethyl ether (50 ml) to afford the pale red product (223
mg, 94%). Anal. Calc. for C186H156Cl3F18P15Ru3: C,
61.93; H, 4.36. Found: C, 61.45; H, 4.66%. IR: (KBr)
1
/
ꢀ
/
ꢀ
/
/
/
/
/
/
/
n(PF) 838 cmꢃ1. UVÁ
cmꢃ1. 1H NMR: (d, 300 MHz, CDCl3); 3.07 (m, 3H, ꢁ
CH), 5.10 (m, 6H, PCH2P), 5.26 (m, 6H, PCH2P), 5.51
(d, Jhh 8Hz, 6H, JHH 8 Hz, H4), 6.98 (d, Jhh 8Hz,
6H, JHH 8 Hz, H5), 7.10Á7.60 (m, 129H, PhꢁC6H3ꢁ
H7ꢁ 15.8. SI
H8). 31P NMR: (d, 121 MHz, CDCl3); ꢃ
MS: 904 ([RuCl(dppm)2ꢂ
H]ꢁ, 40), 868 ([Ru(dppm)2ꢂ
2H]ꢁ, 100).
/
Vis: l (thf) 396 nm, o 19 700 Mꢃ1
/
2.12. trans-[Ru{(E)-4-Cꢀ
/
CC6H4CHꢁ
/
CHPh}Cl(dppm)2]×0.5CH2Cl2 (12)
/
ꢀ
/
ꢀ
/
ꢀ
/
ꢀ
/
/
/
/
trans-[Ru{(E)-4-Cꢁ
/
CHC6H4CHꢁ
/
/
/
CHPh}Cl(dppm)2]PF6 (11) (150 mg, 0.12 mmol) was
stirred in dichloromethane (20 ml) with triethylamine
(1.0 ml) at r.t. for 2 h. The solution was filtered through
an alumina plug and the solvent reduced in volume
under vacuum to afford the yellow product (109 mg,
82%). Anal. Calc. for C66.5H56Cl2P4Ru: C, 69.39; H,
/
/
2.15. 1,3,5-(trans-[(dppm)2ClRu{(E)-4-Cꢀ
/
CC6H4CHꢁCH}])3C6H3 (15)
/
4.90. Found: C, 69.35; H, 5.35%. IR: (CH2Cl2) n(Cꢀ
2073 cmꢃ1. UVÁVis: l (thf) 397 nm, o 23 400 Mꢃ1
cmꢃ1. H NMR: (d, 300 MHz, CDCl3); 4.89 (m, 4H,
PCH2P), 5.27 (s, 1H, CH2Cl2), 6.21 (d, JHH 8 Hz, 2H,
H4), 7.10Á7.60 (m, 49H, PhꢁH5ꢁH7ꢁ
H8). 31P NMR:
(d, 121 MHz, CDCl3); ꢃ
6.0. SI MS: 1109 ([M]ꢁ, 20),
1073 ([Mꢃ
HCl]ꢁ, 20), 905 ([RuCl(dppm)2]ꢁ, 90), 869
([Ru(dppm)2ꢂ
H]ꢁ, 100).
/
C)
[1,3,5-(trans-[(dppm)2ClRu{(E)-4-Cꢁ
/
CHC6H4CHꢁ
/
/
CH}])3C6H3](PF6)3 (14) (154 mg, 0.043 mmol) was
stirred in dichloromethane (25 ml) with triethylamine
(1 ml) at r.t. for 15 min. The solution was filtered
through an alumina plug and the solvent reduced in
volume under vacuum to afford the yellow product (110
mg, 81%). Anal. Calc. for C186H153Cl3P12Ru3: C, 70.48;
1
ꢀ
/
/
/
/
/
/
/
/
H, 4.87. Found: C, 69.46; H, 5.57%. IR: (CH2Cl2) n(Cꢀ
C) 2073 cmꢃ1. UVÁVis: l (thf) 415 nm, o 48 500 Mꢃ1
cmꢃ1. H NMR: (d, 300 MHz, CDCl3); 4.91 (m, 12H,
PCH2P), 6.07 (d, JHH 8 Hz, 6H, H4), 6.90Á7.60 (m,
135H, PhꢁC6H3ꢁH5ꢁH7ꢁ
H8). 31P NMR: (d, 121
MHz, CDCl3); ꢃ
5.9. SI MS: 3169 ([M]ꢁ, 15), 2264
([Mꢃ
RuCl(dppm)2]ꢁ, 5), 904 ([RuCl(dppm)2ꢂH]ꢁ,
40), 869 ([Ru(dppm)2ꢂ
H]ꢁ, 100).
/
/
1
2.13. trans-[Ru{(E)-4-Cꢀ
/
CC6H4CHꢁ
/
CHPh}Cl(dppe)2] (13)
ꢀ
/
/
/
/
/
/
cis-[RuCl2(dppe)2] (150 mg, 0.15 mmol) and (E)-4-
HCꢀCC6H4CHꢁCHPh (3) (38 mg, 0.19 mmol) were
/
/
/
/
/
stirred together in dichloromethane (25 ml) at r.t. for 20
min. NH4PF6 (50 mg, 0.31 mmol) was then added, and
the stirring continued for another 24 h. The solvent was
removed under reduced pressure and the excess acety-
/
2.16. 1,3,5-(trans-[(dppe)2ClRu{(E)-4-Cꢀ
/
CC6H4CHꢁCH}])3C6H3 (16)
/
lene removed by triturating with diethyl ether (3ꢂ30
/
ml). Dichloromethane (15 ml) and triethylamine (1 ml)
were added and the solution stirred for 5 min. Petrol (40
ml) was added, and the resulting precipitate was
collected to afford the yellow product (125 mg, 71%).
Anal. Calc. for C68H59ClP4Ru: C, 71.86; H, 5.23.
cis-[RuCl2(dppe)2] (304 mg, 0.31 mmol) and 1,3,5-
{(E)-4-HCꢀCC6H4CHꢁCH}3C6H3 (5) (32 mg, 0.070
mmol) were stirred together in dichloromethane (25 ml)
at r.t. for 20 min. NH4PF6 (112 mg, 0.69 mmol) was
then added, and the solution refluxed for 15 h. The
solution was then cooled to r.t. and passed through a
sintered-glass funnel. Triethylamine (1.0 ml) was added
/
/
Found: C, 71.31; H, 5.63%. IR: (CH2Cl2) n(Cꢀ
/
C)
2066 cmꢃ1. UVÁVis: l (thf) 404 nm, o 28 600 Mꢃ1
/

S.K. Hurst et al. / Inorganica Chimica Acta 350 (2003) 62Á
/76
67
to the filtrate, the resultant solution was stirred for 5
min, and then the solvent was removed under reduced
pressure. A dichloromethane extract of the yellow
residue was adsorbed onto an alumina column, with
any trans-[RuCl2(dppe)2] being removed by elution with
diethyl ether (400 ml). Elution with dichloromethane
(400 ml) gave the yellow product after addition of petrol
and reduction in solvent volume (173 mg, 76%). Anal.
Calc. for C192H165Cl3P12Ru3: C, 70.88; H, 5.11. Found:
atoms were included in idealized positions, which were
frequently recalculated. The final cycle of full-matrix
least-squares refinement on F was based on 4098
observed reflections (I ꢀ
meters, and converged to Rꢀ
/
2s(I)) and 325 variable para-
0.042. Selected crystal
/
data and structure refinement parameters are collected
in Table 1.
C, 70.60; H, 5.15%. IR: (CH2Cl2) n(Cꢀ
UVÁ
Vis: l (thf) 426 nm, o 87 400 Mꢃ1 cmꢃ1. 1H NMR:
(d, 300 MHz, CDCl3); 2.70 (m, 24H, PCH2CH2P), 6.66
(d, Jhh 8Hz, 6H, JHH 8 Hz, H4), 6.90Á7.60 (m,
135H, PhꢁC6H3ꢁH5ꢁH7ꢁ
H8). 31P NMR: (d, 121
MHz, CDCl3); 50.1. SI MS: 3254 ([M]ꢁ, 5), 3218 ([Mꢃ
HCl]ꢁ, 4), 897 ([Ru(dppe)2ꢂH]ꢁ, 100), 499
([Ru(dppe)ꢂ
H]ꢁ, 100).
/
C) 2062 cmꢃ1
.
2.19. Hyper-Rayleigh scattering measurements
/
The light from an injection-seeded Nd:YAG laser (Q-
switched Nd:YAG Quanta Ray GCR5, 1064 nm, 8 ns
pulses, 10 Hz) was focussed into a cylindrical cell (7 ml)
containing the sample. The intensity of the incident
beam was varied by rotation of a half-wave plate placed
between crossed polarizers. Part of the laser pulse was
sampled by a photodiode to measure the vertically
polarized incident light intensity. The frequency-
doubled light was collected by an efficient condensor
system and detected by a photomultiplier. The harmonic
scattering and linear scattering were distinguished by
appropriate filters; gated integrators were used to obtain
intensities of the incident and harmonic scattered light.
The absence of a luminescence contribution to the
harmonic signal was confirmed by using interference
filters at different wavelengths near 532 nm. All
measurements were performed in tetrahydrofuran using
ꢀ
/
ꢀ
/
/
/
/
/
/
/
/
/
2.17. 1,3,5-(trans-[(dppe)2(PhCꢀ
/
C)Ru{(E)-4-Cꢀ
/
CC6H4CHꢁCH}])3C6H3×CH2Cl2 (17)
/
/
1,3,5-(trans-[(dppe)2ClRu{(E)-4-Cꢀ
CH}])3C6H3 (16) (100 mg, 0.031 mmol), NH4PF6 (30
mg, 0.18 mmol), HCꢀCPh (31 mg, 0.31 mmol) and
/
CC6H4CHꢁ
/
/
triethylamine (1 ml) were stirred in refluxing dichlor-
omethane (25 ml) for 5 h. After this time the solution
was cooled, the solvent removed, and the residue
triturated with petroleum spirit (100 ml) to remove
p-nitroaniline (bꢀ
/
21.4ꢂ
10ꢃ30 esu) [24] as a reference.
Solutions were sufficiently dilute that absorption of
scattered light was negligible. Further details of the
/
excess HCꢀ
filtration
217H182Cl2P12Ru3: C, 73.72; H, 5.19. Found: C,
73.81; H, 5.83%. IR: (CH2Cl2) n(Cꢀ
C) 2057 cmꢃ1
UVÁ
Vis: l (thf) 421 nm, o 129 700 Mꢃ1 cmꢃ1 1H
NMR: (d, 300 MHz, CDCl3); 2.63 (m, 24H,
PCH2CH2P), 5.27 (s, 2H, CH2Cl2), 6.70Á7.60 (m,
156H, PhꢁC6H4ꢁC6H3ꢁH7ꢁ
H8). 31P NMR: (d, 121
MHz, CDCl3); 54.3. SI MS: 3451 ([Mꢁ
H]ꢁ, 3), 3351
([Mꢁ2HꢃCꢀ C)Ruꢂ
CPh]ꢁ, 4), 998 ([(dppe)2(PhCꢀ
H]ꢁ, 100), 897 ([Ru(dppe)2ꢂH]ꢁ, 100).
/CPh. The yellow product was collected by
(60 mg, 57%). Anal. Calc. for
C
/
.
Table 1
Crystal data and structure refinement parameters for 6
/
.
/
Empirical formula
Formula weight
Crystal size (mm)
T (K)
C
662.52
34H26AuP
/
/
/
/
0.24ꢂ
200
0.71069
/0.16ꢂ0.11
/
/
/
/
/
/
/
˚
Wavelength (A)
/
Crystal system
Space group
Unit cell dimensions
monoclinic
P2/n (No. 13)
2.18. X-ray crystallographic study
˚
a (A)
11.1428(6)
6.6249(4)
36.157(2)
98.087(2)
2642.6(2)
4
˚
b (A)
Crystals suitable for the X-ray structural analysis
were grown by liquid diffusion of methanol into a
CHCl3 solution of 6 at r.t. A single yellow needle crystal
was mounted on a fine glass fiber using epoxy glue, and
data were collected at 200 K on a Nonius KappaCCD
diffractometer using graphite-monochromated Mo Ka
radiation. The unit cell parameters were obtained by
least-squares refinement [19] of 32 259 reflections with
˚
c (A)
b (8)
3
˚
V (A )
Z
Index ranges
05
46
5.668
0.676 and 0.298
/
h 5
/
14, ꢃ
/
85
/
k 5
/
8, ꢃ
/
465
/
l 5
/
m (mmꢃ1
)
Max and min transmission
Independent reflections
6054 (Rint
1.27
ꢀ/0.089)
3.55
/
u 527.58. The data were corrected for absorption
/
Goodness-of-fit (I ꢀ
Final R indices (I ꢀ
/
2s(I))
2s(I)) a
/
Rꢀ/0.042, Rwꢀ
/
0.052
using numerical methods [20], implemented from within
MAXUS [21]; equivalent reflections were merged. The
structure was solved by heavy atom Patterson methods
[22] and expanded using Fourier techniques [23]. Non-
hydrogen atoms were refined anisotropically; hydrogen
Largest difference peak and
hole
1.25 and ꢃ
/
1.42
ꢃ3
˚
(e A
)

68
S.K. Hurst et al. / Inorganica Chimica Acta 350 (2003) 62Á76
/
experimental procedure have been reported in the
literature [25,26].
porated on top of the film, so that a sandwich structure
was formed. White light from a tungstenÁhalogen lamp
/
For chromophores exhibiting fluorescence, the HRS
signal can consist of nonlinear scattering and multi-
photon fluorescence (MPF), which results in an over-
estimation of the molecular nonlinearity. To avoid this
problem, the broadband MPF background has been
subtracted from the sharp HRS peak in the spectral
domain [27,28]. However, the most fundamental ap-
proach to resolve this problem is to utilize the difference
in the temporal response between the immediate (hyper-
Rayleigh) scattering and the time-delayed (multi-
photon) fluorescence in the time domain [29]. Measure-
ments at 800 nm were performed implementing a
complete Fourier transform of this approach, using a
laser system with a high repetition rate fs Ti:sapphire
laser (Spectra Physics, Model Tsunami) to obtain a
MPF-free HRS signal. In the frequency domain, we
measured the demodulation and the phase shift acquired
by the fluorescence versus scattering. A more complete
description of this procedure has been given in the
literature [30,31]. All measurements were performed in
tetrahydrofuran using the internal reference method
was monochromated and incident to the film, and
transmitted light was detected by a photodiode. A
low-frequency (137.5 Hz) electric field of approximately
2ꢂ
105 V cmꢃ1 was applied normal to the film, and
/
modulation in the transmitted light intensity at the
doubled frequency (275 Hz) was detected by a lock-in
amplifier, so that the third-order NLO response which is
proportional to the square of the applied electric field
was probed. Measurements were performed in the
spectral range 350Á550 nm.
/
3. Results and discussion
3.1. Synthesis and characterization of organic precursors
The syntheses of the alkynylÁgold and -ruthenium
/
complexes necessitated preparation of new linear and
octopolar stilbenylacetylenes. Sonogashira coupling of
(E)-4-IC6H4CHꢁ/CHPh with trimethylsilylacetylene af-
forded the protected alkyne 1, which was deprotected
with base to give the linear terminal acetylene 2 (Scheme
1). While the current research was in progress, an
(bthf
ꢀ
/
0.33ꢂ
10ꢃ30 esu).
/
2.20. Z-scan measurements
alternative synthesis of
2 was reported, by the
EmmonsÁHorner reaction of 4-ethynylbenzaldehyde
/
Measurements were performed at 800 nm using a
system consisting of a Coherent Mira Ti-sapphire laser
generating a mode-locked train of approximately 100 fs
pulses and a home-built Ti-sapphire regenerative ampli-
fier pumped with a frequency-doubled Q-switched
pulsed Nd:YAG laser (Spectra Physics GCR) at 30 Hz
and employing chirped pulse amplification. Thf solu-
tions were examined in a glass cell with a 1 mm path
length. The Z-scans were recorded at two concentra-
tions for each compound and the real and imaginary
part of the nonlinear phase change determined by
numerical fitting [32]. The real and imaginary parts of
the hyperpolarizability of the solute were then calculated
by assuming linear concentration dependencies of the
solution susceptibility. The nonlinearities and light
intensities were calibrated using measurements of a 1
mm thick silica plate for which the nonlinear refractive
and diethyl benzylphosphonate, but the yield via this
procedure was lower (49%) [18]. The methodology in
Scheme 1 employed for the syntheses of the linear
acetylenes were also used for the syntheses of the
branched acetylenes (Scheme 2). Reaction of excess 4-
IC6H4CHO with 1,3,5-C6H3{CH2P(O)(OEt)2}3 in the
presence of potassium tert-butoxide gave 1,3,5-{(E)-4-
IC6H4CHꢁ
/
CH}3C6H3 (3). Coupling 3 with trimethylsi-
index n2ꢀ
/
3ꢂ
10ꢃ16 cm2 Wꢃ1 was assumed.
/
2.21. Electroabsorption measurements
Complexes 13, 16, and 17 were doped in
a
poly(methyl methacrylate) (PMMA) solution in chloro-
form and spin-coated onto an indiumÁtin-oxide (ITO)-
coated glass substrate. The film thickness was 2.2Á2.5
mm and the complex concentration was approximately 4
wt.%, corresponding to a number density of 2.5ꢂ
1019,
8.6ꢂ
1018 and 9.1ꢂ1018 cmꢃ1, for 13, 16 and 17,
respectively. Semitransparent gold electrodes were eva-
/
/
/
/
/
Scheme 1. Syntheses of 1 and 2.

S.K. Hurst et al. / Inorganica Chimica Acta 350 (2003) 62Á
/76
69
Scheme 2. Syntheses of 3Á5.
/
lylacetylene under Sonogashira conditions gave the
protected acetylene 4, which was deprotected with base
to afford the terminal acetylene 5. The new compounds
ne)gold units being the most abundant ions observed.
All ruthenium complexes except 14 gave mass spectra
with molecular ions or protonated molecular ions. UVÁ
Vis spectra contain bands in the range 335Á339 nm
(linear gold complexes 6Á9), 366 nm (octopolar gold
complex 10), 360Á404 nm (linear ruthenium complexes
11Á13), and 396Á426 nm (octopolar ruthenium com-
plexes 14Á17). The IR spectra of the acetylide complexes
show characteristic coordinated n(CꢀC) bands in the
range 2108Á
2112 cmꢃ1 (gold complexes) and 2057Á
/
were characterized by EI and high-resolution EI mass
1
Vis, IR and H NMR spectroscopy.
/
spectrometry, UVÁ
/
/
/
/
/
3.2. Synthesis and characterization of s-acetylide
complexes
/
/
/
/
The synthetic methodologies employed for the pre-
2073 cmꢃ1 (ruthenium complexes), the spectra of the
vinylidene complexes 11 and 14 having n(PF) bands at
837 and 838 cmꢃ1, respectively. 31P NMR spectra of the
ruthenium complexes contain one singlet resonance,
consistent with trans geometry at the ruthenium center.
paration of the stilbenylalkynylÁgold and -ruthenium
/
complexes are adaptations of those successfully utilized
for the preparation of the corresponding phenylacetylide
complexes. Gold phosphine complexes 6, 7, and 10,
together with previously-unreported complexes 8 and 9,
were prepared in good yield (Scheme 3) by extending the
method of Bruce et al. [33]. The bis{bis(diphenylphos-
3.3. X-ray crystallographic study
phino)alkane}ruthenium complexes 11Á17 were pre-
/
pared (Schemes 4 and 5) by extending the method of
Dixneuf [34].
The identity of 6 was confirmed by a single-crystal X-
ray diffraction study. Crystal data are given in Table 1
and selected bond lengths and angles are compiled in
Table 2. Fig. 2 contains an ORTEP plot showing the
molecular geometry and atomic labeling scheme.
The new complexes were characterized by SI mass
1
spectrometry, UVÁ
/
Vis, IR, H and 31P NMR spectro-
scopy. Mass spectra for the gold complexes contain
weak or non-existent molecular ion signals, (phosphi-

70
S.K. Hurst et al. / Inorganica Chimica Acta 350 (2003) 62Á76
/
Scheme 3. Syntheses of 6Á10.
/
The structural study of 6 confirms the molecular
composition inferred from the spectral data and, in
particular, the E-configured alkene linkage. The Au(1)ꢂ
P(1), Au(1)ꢂC(1) and C(1)ꢂC(2) bond distances are
case, however, Auꢀ ꢀ ꢀAu contacts are all greater than 5
˚
A.
/
/
/
3.4. Electrochemical studies
indistinguishable to those previously observed for re-
lated (phosphine)gold acetylide complexes within the 3s
The electrochemical data for the ruthenium com-
confidence level [16,35Á
/
37]. The angles about the P(1)ꢂ
/
plexes 11Á
nium complexes exhibit reversible or quasi-reversible
processes (in the range 0.46Á0.68 V), whereas the
/17 are gathered in Table 3. The alkynylruthe-
Au(1)ꢂC(1)ꢂC(2) moiety are close to linearity, with
/
/
deviations likely to be the result of crystal packing
forces. Intraphosphine bond lengths and angles in 6 are
/
vinylidene complexes exhibit irreversible processes at
considerably more positive potentials (the latter as
expected for cationic complexes). We have recently
reported a detailed investigation of the electrochemical
behavior of trans-bis(bidentate phosphine)ruthenium
˚
C(10) distance [1.32(1) A] is
not unusual, and the C(9)ꢂ
typical for an E ꢂCꢁ
/
/
/
C unit. Gold complexes have
attracted significant interest as many show aurophilic
Auꢀ ꢀ ꢀAu interactions in the solid state; in the present
Scheme 4. Syntheses of 11Á13.
/

S.K. Hurst et al. / Inorganica Chimica Acta 350 (2003) 62Á
/76
71
Scheme 5. Syntheses of 14Á17.
/
acetylide and vinylidene complexes [38]; the oxidation
potentials and reversibility of processes observed with
the present series of complexes are similar to data for
our previously-reported complexes. In the present study,
Table 2
Selected bond distances (A) and angles (8) for [Au{(E)-4-Cꢀ
CC6H4CHꢁCHPh}(PPh3)] (6)
˚
/
complexes 14Á17 exhibit a single oxidation wave
/
/
indicating that the three ruthenium centers are equiva-
lent, the non-conjugated pathway between the metals
hindering communication.
Bond lengths
Au(1)ꢂP(1)
P(1)ꢂC(121)
Au(1)ꢂC(1)
C(2)ꢂ
C(4)ꢂ
C(6)ꢂ
C(3)ꢂ
C(9)ꢂ
C(11)ꢂ
C(13)ꢂ
C(15)ꢂ
/
2.267(2) P(1)ꢂ
1.828(8) P(1)ꢂ
2.038(9) C(1)ꢂ
/
C(111)
1.815(8)
1.832(8)
1.16(1)
1.41(1)
1.41(1)
1.39(1)
1.47(1)
1.48(1)
1.40(1)
1.35(1)
/
/
C(131)
/
/
C(2)
C(4)
C(6)
C(8)
C(9)
/
C(3)
C(5)
C(7)
C(8)
C(10)
1.42(1)
1.36(1)
1.40(1)
1.41(1)
1.32(1)
1.35(1)
1.39(1)
1.42(1)
C(3)ꢂ
C(5)ꢂ
C(7)ꢂ
C(6)ꢂ
C(10)ꢂ
C(12)ꢂ
C(14)ꢂ
/
/
/
3.5. Nonlinear optical studies
/
/
/
/
/
/
C(11)
C(13)
C(15)
The results of HRS measurements on the precursor
organics and ruthenium complexes are presented in
Table 4, b1064 values corresponding to data at 1064
nm with ns pulses and b800 to data at 800 nm with fs
pulses. Linear optical absorption data are also collected
in Table 4. Trends in optical absorption data (lmax, o)
are relevant to the subsequent discussion of NLO data.
Introduction of a metal center in proceeding from 2 to
/
C(12)
C(14)
C(16)
/
/
/
/
Bond angles
P(1)ꢂAu(1)ꢂ
Au(1)ꢂP(1)ꢂ
Au(1)ꢂC(1)ꢂ
C(2)ꢂC(3)ꢂ
C(4)ꢂC(5)ꢂ
C(6)ꢂC(7)ꢂ
C(3)ꢂC(8)ꢂ
C(7)ꢂC(6)ꢂ
C(9)ꢂC(10)ꢂ
/
/
C(1)
174.4(2) Au(1)ꢂ
115.7(3) Au(1)ꢂ
168.2(8) C(1)ꢂC(2)ꢂ
120.7(7) C(3)ꢂC(4)ꢂ
122.5(8) C(5)ꢂC(6)ꢂ
121.3(7) C(2)ꢂC(3)ꢂ
120.6(8) C(5)ꢂC(6)ꢂ
123.7(7) C(6)ꢂC(9)ꢂ
126.5(9) C(10)ꢂ
/
P(1)ꢂ
/
C(111)
110.4(3)
113.3(3)
174.2(9)
121.4(7)
116.9(8)
121.9(8)
119.3(8)
126.7(8)
122.9(8)
/
/
C(121)
/
P(1)ꢂ
/C(131)
/
/
C(2)
/
/
C(3)
/
/
C(4)
C(6)
C(8)
C(7)
C(9)
/
/
C(5)
C(7)
C(8)
C(9)
C(10)
/
/
/
/
12 or 5 to 15 results in a significant red-shift in lmax
,
/
/
/
/
while proceeding from vinylidene complexes 11, 14 to
alkynyl complexes 12, 15 results in a red-shift in lmax
and increase in o. Progression from linear complexes 11,
12 to octopolar analogues 14, 15 results in a red-shift in
/
/
/
/
/
/
/
/
/
/
C(11)
/
C(11)ꢂC(12)
/

72
S.K. Hurst et al. / Inorganica Chimica Acta 350 (2003) 62Á76
/
Fig. 2. Molecular structure and atomic numbering scheme for [Au{(E)-4-Cꢁ
/
CC6H4CHꢀCHPh}(PPh3)] (6); 30% displacement ellipsoids are
/
shown for the non-hydrogen atoms. Hydrogen atoms have arbitrary radii.
absorption maxima and a two to threefold increase in
oscillator strength.
Table 3
Cyclic voltammetric data a
Complexes 11, 12, 14 and 15 are transparent at the
second-harmonic wavelength of 532 nm, permitting
assessment of the impact of structural variation on
quadratic NLO merit. Nonlinearities for 14 and 15 are
large for octopolar complexes without polarizing accep-
tor substituents, but data for 12, 14 and 15 are
experimentally indistinguishable within the error mar-
gins. Proceeding from vinylidene complex 11 to acet-
ylide complex 12 or tri-vinylidene complex 14 results in
significant increases in quadratic nonlinearity; the
Complex
E1/2 Ru(II/
III) (V)
[ipc/
ipa]
b
trans-[Ru{(E)-4-Cꢁ
CHPh}Cl(dppm)2]PF6 (11)
trans-[Ru{(E)-4-CꢀCC6H4CHꢁ
CHPh}Cl(dppm)2] (12)
trans-[Ru{(E)-4-CꢀCC6H4CHꢁ
CHPh}Cl(dppe)2] (13)
[1,3,5-(trans-[(dppm)2ClRu{(E)-4-Cꢁ
CHC6H4CHꢁCH}])3C6H3](PF6)3 (14)
1,3,5-(trans-[(dppm)2ClRu{(E)-4-Cꢀ
CC6H4CHꢀCH}])3C6H3 (15)
1,3,5-(trans-[(dppe)2ClRu{(E)-4-Cꢀ
CC6H4CHꢁCH}])3C6H3 (16)
1,3,5-(trans-[(dppe)2(PhCꢀC)Ru{(E)-4-Cꢀ
CC6H4CHꢁCH}])3C6H3 (17)
/
CHC6H4CHꢁ
/
1.38
0.46
0.51
1.45
0.68
0.51
0.49
/
/
[0.9]
/
/
[1.0]
b
/
/
/
[1.0]
[0.9]
[1.0]
reversibility of the vinylideneÁacetylide interconversion
/
/
suggests that 11/12 provides a further example of a
protically-switchable NLO system [38]. HRS measure-
ments of 11, 12, 14 and 15 at 800 nm with fs pulses are
also listed in Table 4; fluorescence contributions could
not be completely eliminated from the data for 12, but
are absent from our reported nonlinearities of 11, 14 and
15 (there is no demodulation of the signals for these
complexes as modulation frequency is varied). Proceed-
ing from vinylidene complex 14 to alkynyl complex 15
/
/
/
/
/
a
Ag/AgCl reference electrode, ferroceneÁferrocenium couple (0.56
/
V) as an internal standard.
b
Not reversible.
Table 4
Linear optical spectroscopic and quadratic NLO response parameters a
Compound
lmax (nm)
[o (104 Mꢃ1 cmꢃ1)]
b1064 (10ꢃ30 esu)
b800 (10ꢃ30 esu)
(E)-4-HCꢀ
1,3,5-{(E)-4-IC6H4CHꢁ
1,3,5-{(E)-4-HCꢀCC6H4CHꢁ
trans-[Ru{(E)-4-Cꢁ
trans-[Ru{(E)-4-Cꢀ
[1,3,5-(trans-[(dppm)2ClRu{(E)-4-Cꢁ
1,3,5-(trans-[(dppm)2ClRu{(E)-4-CꢀCC6H4CHꢁ
/
CC6H4CHꢁ
/
CHPh (2)
CH}3C6H3 (3)
CH}3C6H3 (5)
339 [2.2]
340 [6.1]
348 [9.0]
360 [1.5]
397 [2.3]
396 [2.0]
415 [4.9]
37
/
45 (28)
33 (21)
70
/
/
/
CHC6H4CHꢁ
/CHPh}Cl(dppm)2]PF6 (11)
33
/
CC6H4CHꢁ
/CHPh}Cl(dppm)2] (12)
2009
165933 (1019
244950 (150992) 9359
/
40
5
/
920 b
100 (2989
31 (577919)
/
CHC6H4CHꢁ
/
CH])3C6H3](PF6)3 (14)
/
/
62) 4839
/
/62)
/
/
CH}])3C6H3 (15)
/
/
/
/
a
All measurements as thf solutions (all complexes are optically transparent at 1064 and 800 nm). Reported b values are b333; numbers in brackets
are ꢃꢄb2ꢅ. Errors are 9
Upper bound only. No complete demodulation of the fluorescence contribution could be achieved.
/10% unless specified otherwise.
b

S.K. Hurst et al. / Inorganica Chimica Acta 350 (2003) 62Á
/76
73
results in a twofold increase in b800, the latter consistent
with the significant increase in o on this structural
modification, and suggestive of a similar increase in
b1064 obscured by error margins. These complexes are
rare examples of organometallics for which quadratic
optical nonlinearities have been determined at more
than one wavelength. The b800 values for 14 and 15 are
much larger than their b1064 value, consistent with
significant resonance enhancement for the former re-
sulting from close proximity of the optical absorption
maximum to the second-harmonic wavelength (400 nm).
In contrast, the optical absorption maximum for 11 is
more remote from the second-harmonic wavelength,
and the b1064 value is significantly greater than the b800
value.
C)Ru(4-Cꢀ
/
CC6H4Cꢀ
/
C)])3C6H3) (19)] both result in
blue-shifts in lmax
.
Cubic nonlinearities for the organic compounds 2 and
5 are low. We have previously reported cubic NLO data
for (alkynyl)(phosphine/isocyanide/carbene)gold com-
plexes and di(alkynyl)gold complex anions [40Á42], for
/
which nonlinearities are low in most cases. In the present
system, introduction of terminal (phosphine)gold unit in
proceeding from 2 to 6 results in little change in the
linear optical absorption spectra and a negligible non-
linearity. The related yne-linked complexes 8 and 9 have
larger nonlinearities than the ene-linked 6, but values are
very small. The greal values for most of the ruthenium
complexes are negative, and the gimag values are
significant, consistent with two-photon effects contri-
Molecular third-order nonlinearities for many of the
new compounds, as determined by Z-scan at 800 nm,
are collected in Table 5. Note that an electronic origin
for cubic nonlinearities in related metal acetylide com-
plexes has been demonstrated previously by degenerate
four-wave mixing measurements [39], and nonlinearities
for the present series of compounds are, therefore, likely
to be electronic in origin. Table 5 also contains linear
optical absorption maxima and extinction coefficients.
In addition to the aforementioned trends in linear data,
one can observe that replacing dppm by dppe in
proceeding from 12 to 13 or 15 to 16 results in a red-
shift in lmax and increase in o, and extending the p-
system through the metal center (in proceeding from 16
to 17) and replacing ene- with yne-linkage [in proceeding
buting to the observed molecular nonlinearities jgj800
;
comment on the effect of structural variation on the
magnitude of jgj800 is therefore cautious, particularly in
light of the error margins. Nevertheless, several trends
may be noted. Introduction of ligated ruthenium in
proceeding from 5 to 14Á17 results in increased greal and
/
jgj. Replacing dppm by dppe in proceeding from 15 to
16 leads to an increase in jgj800. Extending the p-system
through the metal center, in proceeding from 16 to 17,
and replacing yne with ene linkage, in proceeding from
18 to 16 and 19 to 17, result in significant increases in
jgj800. To the best of our knowledge, the greal value for
17 is the largest thus far for an organometallic complex.
Table 5 also includes TPA cross-sections s2 calculated
from gimag. StructureÁactivity trends are, therefore,
/
from 16 to 1,3,5-(trans-[(dppe)2ClRu(4-Cꢀ
/
CC6H4Cꢀ
/
identical with those of gimag. Thus, s2 values for the
organic acetylenes, gold complexes and vinylidene com-
C)])3C6H3 (18) and 17 to 1,3,5-(trans-[(dppe)2(PhCꢀ
/
Table 5
Linear optical spectroscopic and cubic NLO response parameters a
Compound
lmax (nm)
greal, 800
gimag, 800
½g½
s2 b
800
[o (104 Mꢃ1cmꢃ1)] (10ꢃ36 esu)
(10ꢃ36 esu) (10ꢃ36 esu) (10ꢃ50 cm4 s)
(E)-4-HCꢀ
1,3,5-{(E)-4-HCꢀ
Au{(E)-4-CꢀCC6H4CHꢁ
Au(4-CꢀCC6H4Cꢀ
Au(4-CꢀCC6H4Cꢀ
trans-[Ru{(E)-4-Cꢁ
trans-[Ru{(E)-4-Cꢀ
trans-[Ru{(E)-4-Cꢀ
[1,3,5-(trans-[(dppm)2ClRu{(E)-4-Cꢁ
CH])3C6H3](PF6)3 (14)
1,3,5-(trans-[(dppm)2ClRu{(E)-4-Cꢀ
1,3,5-(trans-[(dppe)2ClRu{(E)-4-CꢀCC6H4CHꢁ
1,3,5-(trans-[(dppe)2ClRu(4-CꢀCC6H4Cꢀ
C)])3C6H3 (18) c
1,3,5-(trans-[(dppe)2(PhCꢀC)Ru{(E)-4-Cꢀ
CH}])3C6H3 (17)
/
CC6H4CHꢁ
CC6H4CHꢁ
CHPh}(PPh3) (6)
/
CHPh (2)
339 [2.2]
348 [9.0]
338 [1.7]
336 [6.5]
335 [5.5]
360 [1.5]
397 [2.3]
404 [2.9]
396 [2.0]
1009
3309
09
9009
2009
200
6009
3009
9009
/
60
09
959
/
20
50
1009
/
60
09
229
/
5
/
/
CH}3C6H3 (5)
/150
/
3409
/
160
/
12
/
/
/
300
09
09
09
/
50
0
09
09
09
/
12
24
12
/
/CPh)(PPh3) (8)
ꢃ
/
/
400
150
/
100
50
9009
2009
909
9209
4209
/
400
/
/
/CPh)(PMe3) (9)
ꢃ
/
/
/
/150
/
/
CHC6H4CHꢁ
CC6H4CHꢁ
CC6H4CHꢁ
/
CHPh}Cl(dppm)2]PF6 (11)
B
ꢃ/
/
909
7009
3009
7009
/50
/
50
219
1709
70930
/
12
/
/
CHPh}Cl(dppm)2] (12)
/
400
/
400
100
400
/600
/
100
/
/
CHPh}Cl(dppe)2] (13)
/400
/
/350
/
/
CHC6H4CHꢁ
/
ꢃ/
/
500
/
11009
/
700 1709
/100
/
CC6H4CHꢁ
/
CH}])3C6H3 (15) 415 [4.9]
ꢃ
/
6409
/
500
20009
800 62009
22009500 22009600 5309
860092000 14 0009
4000
500 30009
/500 21009
/
600 4809
/120
/
/
CH}])3C6H3 (16)
426 [8.7]
414 [10.4]
421 [13.0]
ꢃ
/
46009
/
2000 42009
/
/
2000 10009
/200
/
/
ꢃ
/
3309100
/
/
/
/120
/
/
CC6H4CHꢁ
/
ꢃ
/
11 2009
/
/
/
21009
/500
3000
1,3,5-(trans-[(dppe)2(PhCꢀ
/
C)Ru(4-Cꢀ
/
CC6H4Cꢀ
/
C)])3C6H3 (19) d
411 [11.6]
ꢃ
/
6009
/
200
29009
/
/
600 6909
/120
a
All measurements as thf solutions (all complexes are optically transparent at 800 nm).
b
c
Calculated using the equation s2ꢀhb/2pN, where b is the TPA coefficient [50].
/
[8].
Ref. [6].
d

74
S.K. Hurst et al. / Inorganica Chimica Acta 350 (2003) 62Á76
/
plex 11 are small, and progression from vinylidene to
acetylide complex, linear to octopolar complex, and yne
to ene linkage all result in increases in s2. It is worth
noting that the datum for 17 is of the same order of
magnitude as that of the best organics [43,44], and one
of the largest thus far for an organometallic complex
[7,41].
the wavelength dispersion effects are expected to work
in different ways for the two processes, although both
are resonantly-enhanced. A close correspondence in Z-
scan and EA-derived nonlinearities, is therefore, not
expected.
Third-order nonlinear susceptibilities x(3) were also
determined for 13, 16, and 17 by EA spectral measure-
4. Discussion
ments at 350Á550 nm: this is the first application of EA
/
The present studies have demonstrated the facile
spectroscopy to evaluate cubic nonlinearities of organo-
metallics, although it has been utilized in this regard
with organic compounds and coordination complexes
synthesis of novel two-dimensional octopolar alkynylÁ
/
gold and -ruthenium complexes incorporating pheny-
lethenyl spacer units, as well as linear complexes
corresponding to the ‘legs’ of these organometallic
triskelia [49]. We have previously reported extension of
the phenylethynyl spacer system to encompass dendritic
examples [7]; extending the present series of complexes
(for which 17 could be considered a zero-generation
dendrimer) to include higher-generation dendrimers
should (similarly) proceed smoothly. The 1,3,5-branch-
ing at the core effectively insulates the metal centers,
reflected in oxidation of the ruthenium examples as
assessed by cyclic voltammetry.
[45,46]. In contrast to Z-scan, which measures x(3)(ꢃ
/
v:v,ꢃ
/
v,v) for interacting light waves of frequency v,
the quadratic EA effect measures x(3)(ꢃ
/v:v,0,0) for
which the zero frequencies correspond to the dc electric
field; the techniques are, therefore, complementary, in
that they sample different NLO interactions. The linear
optical absorption maxima and Im(x(3))/N values, the
imaginary parts of the EA-derived nonlinear suscept-
ibility normalized by the number density of molecules in
PMMA matrix, are summarized in Table 6. The optical
absorption maxima for 13, 16, and 17 undergo blue
Introduction of phenylethenyl groups results in an
increase in both quadratic and cubic NLO responses
compared with those observed previously for examples
constructed with phenylethynyl spacers. Quadratic non-
linearities for 14 and 15 at both 800 and 1064 nm are
very large for octopolar compounds lacking strong
acceptor groups. HRS data can be enhanced by
fluorescence contributions. Frequency modulation has
been utilized with the present complexes to confirm the
fluorescence-free b800 data for 14 and 15, and therefore,
the surprisingly large nonlinearities for these com-
pounds.
Significant increases in molecular cubic nonlinearity
jgj800 and TPA cross-section s2 are observed on
proceeding from the linear complexes to the octopolar
analogues, with the TPA cross-section for 17 one of the
largest reported thus far. The significant bHRS and s2
shifts of 3Á6 nm on proceeding from thf solution to
/
solid solution in PMMA. The Im(x(3))/N values for the
complexes in PMMA reach a negative peak at wave-
lengths approximately 20 nm longer than lmax, and a
positive peak at wavelengths approximately 50 nm
longer than lmax. Im(x(3))/N values for 16 and 17 are
not greatly different to each other, but are threefold that
for 13, reflecting the number of ligated ruthenium
centers in these molecules.
Very few third-order NLO data for organometallics
doped into organic polymer hosts exist [47,48], and
comparison to solution-derived data is rare. The
Im(x(3))/N values of 13, 16, and 17 in the present work
are one to two orders of magnitude larger than their
molecular cubic nonlinearities g obtained by Z-scan.
There are at least two important factors giving rise to
this variance. Firstly, division by a local field factor
magnitude difference for vinylideneÁacetylide complex
/
Lv2L02 is needed to convert x(3)/N to g; assuming Lv ꢀ
(ovꢁ2)/3, one can estimate this as a factor of approxi-
mately four for these solid solution samples. Secondly,
/
pairs in the present studies have afforded further
examples of protically-switchable NLO materials [8].
Finally, the utility of EA spectroscopy to determine
/
Table 6
Cubic NLO response parameters in solid solution in PMMA measured by EA spectroscopy
Compound
lmax (nm) Im(x(3))/N (negative peak) a Im(x(3))/N (positive peak) a
(10ꢃ36 esu) @ l (nm) b
(10ꢃ36 esu) @ l (nm) b
trans-[Ru{(E)-4-Cꢀ
1,3,5-(trans-[(dppe)2ClRu{(E)-4-Cꢀ
1,3,5-(trans-[(dppe)2(PhCꢀC)Ru{(E)-4-Cꢀ
/
CC6H4CHꢁ
/
CHPh}Cl(dppe)2] (13)
CC6H4CHꢁCH}])3C6H3 (16)
CC6H4CHꢁ
400
420
ꢃ
/
31 000 @ 420
120 000 @ 438
95000 @ 436
36 000 @ 452
100 000 @ 472
77000 @ 472
/
/
ꢃ
/
/
/
/
CH}])3C6H3 (17) 418
ꢃ/
a
In order to cancel the influence of concentration, x(3) was normalized by the number density of the molecule N (cmꢃ3) in PMMA matrix.
Peak value at the wavelength written after @.
b

S.K. Hurst et al. / Inorganica Chimica Acta 350 (2003) 62Á
/76
75
[9] H.S. Nalwa, T. Watanabe, S. Miyata, in: H.S. Nalwa, S. Miyata
(Eds.), Nonlinear Optics of Organic Molecules and Polymers,
CRC Press, Boca Raton, FL, 1997, p. 121.
cubic nonlinearities of organometallics has been demon-
strated for the first time; the Im(x(3))/N values of the
complexes studied are large and scale with the number
of metal atoms.
[10] B. Chaudret, G. Commenges, R. Poilblanc, J. Chem. Soc., Dalton
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5. Supplementary material
Crystallographic data (excluding structure factors) for
the structure reported in this paper have been deposited
with the Cambridge Crystallographic Data Center,
CCDC No. 182950 (6). Copies of this information
may be obtained, free of charge, on application to The
Director, CCDC, 12 Union Road, Cambridge, CB2
[15] C.A. McAuliffe, R.V. Parish, P.D. Randall, J. Chem. Soc.,
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1EZ, UK (fax: ꢁ44-1223-336-033; e-mail: deposit@
ccdc.cam.ac.uk or www: http://www.ccdc.cam.ac.uk).
/
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M.G.H. thanks the Australian Research Council
(ARC) for financial support, Johnson-Matthey Tech-
nology Center for the generous loan of ruthenium salts,
the ARC for an Australian Senior Research Fellowship
and the Science and Technology Agency of Japan (STA)
for a Fellowship. A.P. thanks the Belgian Government
(Grant No. IUAP-IV/11), the Fund for Scientific
Research-Flanders (G.0338.98, G.0407.98) (AP), and
the K.U. Leuven (GOA/2000/03) (AP) for support of
this work. T.I. thanks the Japan Science and Technol-
ogy Corporation for partial support of this work
through the Core Research for Evolutional Science
and Technology (CREST) program (‘Hyper-Structured
Molecules and Their Application to Organic Quantum
Devices’ project headed by Professor H. Sasabe (Chitose
Institute of Science and Technology, Japan)).
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