Syntheses and second-order optical nonlinearity of ruthenium σ-acetylides with an end-capping organic electron acceptor and thienyl entity in the conjugation chain

Article abstract of DOI:10.1021/om970947i

Ruthenium σ-acetylides with an end-capping organic electron acceptor and thienyl entity in the conjugation chain, Ru(C≡C - Y)(PPh₃)₂(η⁵-C₅H₅) (Y = th-CHO, th-CH=C(CN)₂, th-(E)-CH=CH-th-CHO,

Full text of DOI:10.1021/om970947i

2188
Organometallics 1998, 17, 2188-2198
Syn th eses a n d Secon d -Or d er Op tica l Non lin ea r ity of
Ru th en iu m σ-Acetylid es w ith a n En d -Ca p p in g Or ga n ic
Electr on Accep tor a n d Th ien yl En tity in th e Con ju ga tion
Ch a in
Iuan-Yuan Wu,† J iann T. Lin,*,† J immy Luo,‡ Chyi-Shiun Li,† Chiitang Tsai,‡
Yuh S. Wen,† Chia-Chen Hsu,*,§ Fen-Fen Yeh,§ and Sean Liou§
Institute of Chemistry, Academia Sinica, Nankang, Taipei, Taiwan, Republic of China,
Department of Chemistry, Chinese Culture University, Taipei, Taiwan, Republic of China, and
Department of Physics, National Chung Cheng University, Ming-Hsiung, Chia-Yi,
Taiwan, Republic of China
Received October 30, 1997
Ruthenium σ-acetylides with an end-capping organic electron acceptor and thienyl entity
in the conjugation chain, Ru(CtCsY)(PPh3)2(η5-C5H5) (Y ) th-CHO, th-CHdC(CN)2, th-
(E)-CHdCH-th-CHO, th-(E)-CHdCH-th-CHdC(CN)2, C6H4-(E)-CHdCH-th-NO2, th-(E)-
CHdCHC6H4-4-NO2, C6H4CtC-th-NO2, th-(E)-CHdCH-th-CHdCHC6H4-4-NO2, C6H4NdC(H)-
th-NO2, th-(E)-CHdCHC5H4N+Me, th-CtCC5H4N+Me, th-(E)-CHdCH-th-NO2, th-CtC-th-
NO2) (th ) 2,5-disubstituted thiophene), were synthesized. These complexes exhibit intense
charge transfer from the ruthenium donor to the organic acceptor. The quadratic hyper-
polarizabilities of the selected complexes were determined using the hyper Rayleigh scattering
method. Single-crystal X-ray analysis was employed to examine the structures of Ru-
(CtCC6H4-(E)-CHdCH-th-NO2)(PPh3)2(η5-C5H5) and Ru(CtC-th-CHdC(CN)2)(PPh3)2(η5-
C5H5).
In tr od u ction
such ruthenium complexes which exhibited good qua-
dratic hyperpolarizability. In our continuation of desig-
ing second-order nonlinear optical materials, we turned
our attention to thiophene moiety which has been
successfully used in organic chromophores.9 The re-
duced aromaticity of thiophene as compared to benzene
(stabilization energy: thiophene, 29 kcal mol-1; benzene,
36 kcal mol-1) would allow better electron delocaliza-
tion.10 In this report, we describe the syntheses of a
series of CpRu(L)2 σ-acetylide complexes incorporating
one or two thienyl entity in the conjugation chain. A
preliminary study on second-order optical nonlinearity
is also presented.
There are growing interests in organometallic non-
linear optics1 since the first report in this area by
Green.2 Organometallic complexes are attractive be-
cause of the facile modification of their properties by
either altering the metals themselves or their bystander
ligands. Organometallic fragments have been demon-
strated to be able to act as potential electron donors or
electron acceptors in second-order nonlinear optical
chromophores.3 Among organometallic electron donors,
ferrocenyl4 and CpRu(L)2 (L ) phosphine)5 moieties
seem to be promising candidates. Coplanarity of the
metals and the π-electrons was suggested to be benefi-
cial for optical nonlinearity;6 accordingly, CpRu(L)2
σ-acetylide complexes with appropriate electron acceptor
are expected to have reasonable optical nonlinearity.
Recently we7 and others8 synthesized several series of
Exp er im en ta l Section
The general procedures and physical measurements re-
semble those described in an earlier report.7 Compounds
(7) Wu, I. Y.; Lin, J . T.; Sun, S. S.; Luo, J .; Li, C. S.; Wen, Y. S.;
Tsai, C. T.; Chia-Chen Hsu, C. C.; Lin, J . L. Organometallics 1997,
16, 2038.
† Academia Sinica.
‡ Chinese Culture University.
§ National Chung Cheng University.
(1) (a) Long, N. J . Angew. Chem., Int. Ed. Engl. 1995, 34, 21. (b)
Kanis, D. R.; Ratner, M. A.; Marks, T. J . J . Am. Chem. Soc. 1992, 114,
10338.
(2) Green, M. L. H.; Marder, S. R.; Thompson, M. E.; Bandy, J . A.;
Bloor, D.; Kolinsky, P. V.; J ones, K. J . Nature (London) 1987, 330, 360.
(3) (a) Kanis, D. R.; Lacroix, P. G.; Ratner, M. A.; Marks, T. J . J .
Am. Chem. Soc. 1994, 116, 10089. (b) Kanis, D. R.; Ratner, M. A.;
Marks, T. J . Chem. Rev. 1994, 94, 195.
(4) (a) Alain, V.; Fort, A.; Barzoukas, M.; Chen, C. T.; Blanchard-
Desce, M.; Marder, S. R.; Perry, J . W. Inorg. Chim. Acta 1996, 242,
43. (b) Alain, V.; Blanchard-Desce, M.; Chen, C. T.; Marder, S. R.; Fort,
A.; Barzoukas, M. Inorg. Chim. Acta 1996.
(8) (a) Whittall, I. R.; Humphrey, M. G.; Hockless, D. C. R.; Skelton,
B. W.; White, A. H. Organometallics 1995, 14, 3970. (b) Whittall, I.
R.; Humphrey, M. G.; Persoons, A.; Houbrechts, S. Organometallics
1996, 15, 1935. (c) Houbrechts, S.; Clays, K.; Persoons, A.; Cadierno,
V.; Gamasa, M. P.; Gimeno, J . Organometallics 1996, 15, 5266.
(9) (a) Branger, C.; Lequan, M.; Lequan, R. M.; Barzoukas, M.; Fort,
A. J . Mater. Chem. 1996, 6, 555. (b) Chou, S. S. P.; Sun, D. J .; Lin, H.
C.; Yang, P. K. J . Chem. Soc., Chem. Commun. 1996, 1045. (c)
Hutchings, M. G.; Ferguson, I.; McGreen, D. J .; Morley, J . O.; Zyss,
J .; Ledoux, I. J . Chem. Soc., Dalton Trans. 1995, 171. (d). Rao, V. P.;
J en, A. K. Y.; Wong, K. Y.; Drost, K. J . J . Chem. Soc., Chem. Commun.
1993, 1118.
(10) Wheland, F. Resonance in Organic Chemistry; Wiley: New
York, 1955; p 99. (b) March, J . Advanced Organic Chemistry, 4th ed.;
Wiley: New York, 1992; p 45. (c) Bird, C. W.; Cheeseman, G. W. H. In
Comprehensive Heterocyclic Chemistry; Pergamon: Oxford, U.K., 1984;
Vol. 4, pp 28-30.
(5) Laidlaw, W. M.; Denning, R. G.; Verbiest, T.; Chauchard, E.;
Persoons, A. Nature (London) 1993, 363, 58.
(6) Calabrese, J . C.; Cheng, L. T.; Green, J . C.; Marder, S. R.; Tam,
W. J . Am. Chem. Soc. 1992, 113, 7227.
S0276-7333(97)00947-3 CCC: $15.00 © 1998 American Chemical Society
Publication on Web 04/29/1998

Ruthenium σ-Acetylides
Organometallics, Vol. 17, No. 11, 1998 2189
RuCl(PPh3)2(η5-C5H5),11 [Ph3PCH2C6H4NO2-4][Br],8b 4-ethyn-
ylaniline,12 4-ethynylpyridine,13 5-bromo-2-iodothiophene,14
2,5-diethynylthiophene,15 and (2-thienylmethyl)triphenylphos-
phonium chloride16 were prepared by following published
methods. (E)-1-(5-bromo-2-thienyl)-2-(5-formyl-2-thienyl)eth-
ylene and (E)-1-(5-bromo-2-thienyl)-2-(5-nitro-2-thienyl)ethyl-
ene were prepared by published procedures with modifica-
tions.17
of the solvent, the residue was extracted with CH2Cl2/H2O (1:
1). The organic layer was collected, dried over MgSO4, filtered,
and pumped dry. The residue was chromatographed using
hexane as eluent to afford yellow powdery 3a in 74% yield. IR
(KBr, cm-1): 2139 (s), ν(CtC); 1662 (s), ν(CO). 1H NMR
3
(CDCl3): δ 9.83 (s, 1 H, CHO), 7.63 (d, 1 H, J H-H ) 3.9 Hz,
3
SCCH), 7.13 (d, 1 H, J H-H ) 16.0 Hz, CHd), 7.10 (d, 2 H, 3.9
Hz, SCCH), 6.96 (d, 1 H, CHd), 6.95 (d, 1 H, SCCH), 0.24 (s,
9 H, CH3).
5-Eth yn yl-2-for m ylth iop h en e (1). To a flask containing
5-bromo-2-thiophenecarboxaldehyde (9.55 g, 50.0 mmol), PdCl2-
(PPh3)2 (0.701 g, 1.00 mmol), CuI (0.096 g, 0.50 mmol), and
Et2NH (150 mL) was added (trimethylsilyl)acetylene (7.7 mL,
54.6 mmol). The resulting mixture was stirred at 0 °C for 30
min, allowed to warm to room temperature, and stirred for 12
h. The solvent was removed under vacuum, and the residue
was extracted with Et2O. Removal of Et2O provided a brown-
black oil, which was then chromatographed. Elution with CH2-
Cl2/hexane (1:1) gave a yellow band from which powdery
2-formyl-5-((trimethylsilyl)ethynyl)thiophene (1a ) was isolated
in 86% yield (8.96 g) after removal of solvent. 1H NMR
Powdery KOH (160 mg, 2.86 mmol) was added to a solution
of 3a (850 mg, 2.69 mmol) in 40 mL of MeOH, and the resulting
solution was stirred at room temperature for 10 h. A 100 mL
of H2O was added, and the solution was filtered. The solid
collected was recrystallized from CH2Cl2 to give an orange-
yellow powdery 3 in 100% yield (590 mg). MS (EI): m/e 244
(M+). IR (KBr, cm-1): 1657 (s), ν(CO). 1H NMR (CDCl3): δ
3
9.84 (s, 1 H, CHO), 7.63 (d, 1 H, J H-H ) 3.9 Hz, SCCH), 7.16
(d, 1 H, 3J H-H ) 3.9 Hz, SCCH), 7.15 (d, 1 H, 3J H-H ) 15.9 Hz,
CHd), 7.11 (d, 1 H, 3J H-H ) 3.9 Hz, SCCH), 6.98 (d, 1 H, CHd),
6.97 (d, 1 H, 3J H-H ) 3.9 Hz, SCCH), 3.43 (s, 1 H, CHt). Anal.
Calcd for C13H8OS2: C, 63.90; H, 3.30. Found: C, 64.26; H,
3.19.
3
(CDCl3): δ 9.82 (s, 1 H, CHO), 7.59 (d, 1 H, J H-H ) 3.9 Hz,
SCCH), 7.23 (d, 1 H, SCCH), 0.24 (s, 9 H, CH3).
Ru (CtC-th -(E)-CHdCH-th -CHO)(P P h 3)2(η5-C5H5) (4).
Powdery KOH (1.50 g, 26.8 mmol) was added to a solution
of 1a (4.17 g, 20.0 mmol) in 80 mL of MeOH, and the resulting
solution was stirred at room temperature for 40 min. The
addition of a mixture of H2O (100 mL) and CH2Cl2 (100 mL)
resulted in two layers. The aqueous layer was further washed
with CH2Cl2 (2 × 50 mL), and the CH2Cl2 washings were
combined with the organic layer and dried over MgSO4. The
solution was filtered, and the filtrate was pumped dry. The
crude product was chromatographed using CH2Cl2/hexane (1:
4) as eluent to afford 1 as a colorless powder in 92% yield (2.51
g). 1H NMR (CDCl3): δ 9.85 (s, 1 H, CHO), 7.62 (d, 1 H, 3J H-H
) 3.9 Hz, SCCH), 7.29 (d, 1 H, SCCH), 3.56 (s, 1 H, tCH).
Anal. Calcd for C7H4OS: C, 61.74; H, 2.96. Found: C, 61.49;
H, 2.78.
Ru (CtC-th -CHO)(P P h 3)2(η5-C5H5) (2; th ) 2,5-Su bsti-
tu ted Th iop h en e). To a mixture of RuCl(PPh3)2(η5-C5H5)
(726 mg, 1.00 mmol) and 2-ethynyl-5-nitrothiophene (163 mg,
1.20 mmol) was added 50 mL of MeOH. The resulting mixture
was heated at 50 °C for 30 min. The dark green solution
formed was cooled to room temperature, and a solution of
NaOMe, prepared in situ from Na (40 mg, 1.74 mmol) and
MeOH (10 mL), was added. The resulting yellow solution was
pumped dry, and the residue was chromatographed using CH2-
Cl2 as eluent to afford 2 as a yellow powder (560 mg, 68%).
MS (FAB): m/e 826 (M+, 102Ru). IR (KBr, cm-1): 2037 (s),
ν(CtC); 1644 (s), ν(CO). 13C NMR (CD2Cl2): δ 181.0 (s, CHO),
145.8 (t, J C-P ) 24.5, Ru-CtC), 141.5 (s, dCS), 138.3 (t, J C-P
) 21.6, Cipso of PPh3), 138.2 (s, dCH), 136.7 (s, dCS), 133.6 (t,
J C-P ) 4.7, Cortho of PPh3), 128.7 (s, Cpara of PPh3), 127.4 (t,
J C-P ) 4.1, Cmeta of PPh3), 126.5 (s, dCH), 109.6 (s, RuCtC),
85.8 (s, C5H5). Anal. Calcd for C48H38OP2SRu: C, 69.81; H,
4.64. Found: C, 69.96; H, 4.78.
To a mixture of RuCl(PPh3)2(η5-C5H5) (605 mg, 0.83 mmol),
-
NH4+PF6 (163 mg, 1.00 mmol), and 3 (244 mg, 1.00 mmol)
was added 50 mL of CH2Cl2 and 25 mL of MeOH. The
resulting mixture was stirred at room temperature for 14 h.
The solvent was removed under vacuum, and the residue was
extracted with CH2Cl2 (30 mL). The CH2Cl2 solution was
filtered through Celite, and the solid was further washed with
CH2Cl2 (2 × 10 mL). The filtrate was then slowly added to a
mixture of Et2O and hexane (1:5 by volume, 350 mL) with
rapid stirring. The solution was filtered, and the solid was
dissolved in a mixture of acetone and MeOH (1:1 by volume,
50 mL). A solution of NaOMe (23 mg, 1.00 mmol) in 5 mL of
MeOH was added, and the solution was stirred at room
temperature for 5 min. After addition of 25 mL of H2O the
solution was filtered. The collected precipitate was washed
with cold MeOH (2 × 5 mL) and dried to provide 4 as a dark
purple powder (600 mg, 78%). MS (FAB): m/e 934 (M+, 102Ru).
IR (KBr, cm-1): 2043 (s), ν(CtC); 1657 (s), ν(CO). 13C NMR
(CD2Cl2): δ 182.1 (s, CHO), 153.1 (s, dCS), 140.4 (s, dCS),
138.6 (t, J C-P ) 21.6, Cipso of PPh3), 137.5 (s, dCH), 135.6 (t,
J C-P ) 24.6, Ru-CtC), 135.2 (s, dCS), 133.7 (t, J C-P ) 4.7,
Cortho of PPh3), 133.2 (s, dCS), 129.6 (s, dCH), 128.6 (s, Cpara
of PPh3), 127.4 (t, J C-P ) 4.1, Cmeta of PPh3), 126.7 (s, dCH),
126.1 (s, dCH), 125.4 (s, dCH), 116.7 (s, dCH), 108.4 (s,
RuCtC), 85.6 (s, C5H5). Anal. Calcd for C54H42OP2S2Ru: C,
69.44; H, 4.53. Found: C, 69.62; H, 4.68.
(E )-1-(5-Nit r o-2-t h ie n yl))-2-(4-e t h yn ylp h e n yl)e t h yl-
en e (5). THF (100 mL) was added to a flask containing a
mixture of [Ph3PCH2C6H4Br-4][Br] (5.80 g, 11.3 mmol), 5-nitro-
2-thiophenecarboxaldehyde (2.00 g, 12.4 mmol), and NaH (388
mg, 16.2 mmol). The resulting mixture was stirred at room
temperature for 48 h, and the solvent was removed in vacuo.
The residue was dissolved in CH2Cl2 and filtered. MeOH was
slowly added to the filtrate until effervescence ceased. After
the solvent was removed, the residue was chromatographed
using CH2Cl2/hexane (2:3) as eluent. The yellow powdery (E)-
1-(4-bromophenyl)-2-(5-nitro-2-thienyl)ethylene (5a ) was iso-
lated in 36% yield (1.26 g) from the second band. 1H NMR
(E)-1-(5-F or m yl-2-t h ien yl)-2-(5-et h yn yl-2-t h ien yl)et h -
ylen e (3). (E)-1-(5-bromo-2-thienyl)-2-(5-formyl-2-thienyl)-
ethylene was utilized to synthesize (E)-1-(5-formyl-2-thienyl)-
2-(5-(trimethylsilyl)ethynyl-2-thienyl)ethylene (3a ) by a proce-
dure similar to that employed for 1a , and the reaction
proceeded at room temperature for 2.5 days. After removal
3
(CDCl3): δ 7.81 (d, 1 H, J H-H ) 4.5 Hz, SCCH), 6.98 (d, 1 H,
(11) Bruce, M. I.; Hameister, C.; Swincer, A. G.; Wallis, R. C. Inorg.
Chem. 1990, 28, 270.
(12) Takahashi, S.; Kuroyama, Y.; Sonogashira, K.; Hagihara, N.
Synthesis 1980, 627.
(13) Ciana, L. D.; Haim, A. J . Heterocycl. Chem. 1984, 21, 607.
(14) Gronowitz, S.; Holm, B. Acta Chem. Scand. B 1976, 30, 423.
(15) (a) Viola, E.; Sterzo, C. L.; Crescenzi, R.; Frachey, G. J .
Organomet. Chem. 1995, 493, C9. (b) Neenan, T. X.; Whitesides, G.
M. J . Org. Chem. 1988, 53, 2489.
(16) Zhang, J . X.; Dubois, P.; J erome, R. Synth. Commun. 1996, 26,
3091.
SCCH), 7.49 (d, 2 H, 3J H-H ) 8.7 Hz, C6H4), 7.34 (d, 2 H, C6H4),
3
7.10 (d, 1 H, J H-H ) 17.2 Hz, CHd), 7.03 (d, 1 H, CHd).
Compound 5a was converted to (E)-1-(5-nitro-2-thienyl)-2-
(4-(trimethylsilyl)ethynylphenyl)ethylene (5b) by the same
procedures as employed for 1, except that the reaction pro-
ceeded at 60 °C for 48 h. After the solvent was removed, the
residue was chromatographed using CH2Cl2/hexane (1:1) as
eluent to afford the bright yellow powdery 5b in 76% yield.
1H NMR (CDCl3): δ 7.81 (d, 1 H, 3J H-H ) 4.5 Hz, SCCH), 7.45
(17) Manecke, G.; Ha¨rtel, M. Chem. Ber. 1973, 106, 655.

2190 Organometallics, Vol. 17, No. 11, 1998
Wu et al.
3
(d, 2 H, J H-H ) 8.7 Hz, C6H4), 7.41 (d, 2 H, C6H4), 7.12 (d, 1
Cl2): δ 145.7 (s, CNO2), 144.6 (s, CCCCNO2), 138.4 (t, J C-P
)
21.2, Cipso of PPh3), 135.6 (s, dCS), 135.0 (t, J C-P ) 24.9, Ru-
CtC), 133.7 (t, J C-P ) 4.6, Cortho of PPh3), 133.3 (s, dCS), 129.6
(s, dCH), 128.6 (s, Cpara of PPh3), 127.3 (t, J C-P ) 4.0, Cmeta of
PPh3), 127.2 (s, dCH), 126.2 (s, dCH), 125.9 (s, C6H4), 124.2
(s, C6H4), 122.0 (s, dCH), 108.3 (s, RuCtC), 85.5 (s, C5H5).
Anal. Calcd for C55H43NO2P2SRu: C, 69.90; H, 4.59; N, 1.48.
Found: C, 69.69; H, 4.71; N, 1.47.
3
H, J H-H ) 16.2 Hz, CHd), 7.06 (d, 1 H, CHd), 6.98 (d, 1 H,
SCCH), 0.24 (s, 9 H, CH3).
A solution of 5b (800 mg, 2.40 mmol) in 50 mL of THF was
added a solution of (n-Bu)4N+F- (770 mg, 2.80 mmol) in 10
mL of THF, and the resulting solution was stirred at room
temperature for 20 min. The solvent was removed, and the
residue was chromatographed using CH2Cl2/hexane (2:3) as
eluent. The orange-yellow powdery 5 was isolated in 77% yield
(477 mg) from the first band. 1H NMR (CDCl3): δ 7.82 (d, 1
H, 3J H-H ) 4.5 Hz, SCCH), 7.48 (d, 2 H, 3J H-H ) 8.7 Hz, C6H4),
(4-Eth yn ylp h en yl)(5-n itr o-2-th ien yl)a cetylen e (10). To
a mixture of 4-bromophenylacetylene (2.00 g, 11.0 mmol),
2-bromo-5-nitrothiophene (2.29 g, 11.0 mmol), PdCl2(PPh3)2
(150 mg, 0.21 mmol), and CuI (40 mg, 0.21 mmol) was added
100 mL of Et3N, and the resulting mixture stirred at room
temperature for 10 h. The solvent was removed under vacuum
and the residue extracted with CH2Cl2/hexane (1:1). The
organic layer was pumped dry, and the residual solid was
chromatographed. The bright yellow powdery (4-bromophen-
yl)(5-nitro-2-thienyl)acetylene (10a ) was isolated in 62% yield
(2.11 g) from the second band. 1H NMR (CDCl3): δ 7.81 (d, 1
H, 3J H-H ) 4.2 Hz, SCCH), 7.51 (d, 2 H, 3J H-H ) 8.4 Hz, C6H4),
7.38 (d, 2 H, C6H4), 7.14 (d, 1 H, SCCH).
3
7.43 (d, 2 H, C6H4), 7.13 (d, 1 H, J H-H ) 16.2 Hz, CHd), 7.07
(d, 1 H, CHd), 6.99 (d, 1 H, SCCH), 3.16 (s, 1 H, CHt). Anal.
Calcd for C14H9NO2S: C, 65.87; H, 3.55; N, 5.49. Found: C,
65.66; H, 3.40; N, 5.39.
[Ru(dCdC(H)C6H5-(E)-CHdCH-th-NO2)(P P h 3)2(η5-C5H5)]-
[P F 6] (6). To a mixture of RuCl(PPh3)2(η5-C5H5) (200 mg, 0.27
mmol), NH4+PF6 (56 mg, 0.32 mmol), and 5 (73 mg, 0.27
-
mmol) was added 80 mL of CH2Cl2 and 20 mL of MeOH. The
resulting mixture was stirred at room temperature for 10 h.
The solvent was removed under vacuum, and the residue was
recrystallized from CH2Cl2/hexane to afford dark red powdery
6 in 93% yield (280 mg). 1H NMR (CDCl3): δ 7.80 (d, 1 H,
3J H-H ) 4.5 Hz, SCCH), 7.41-7.69 (m, 37 H, Ph, SCCH, and
Compound 10a was then converted to (5-nitro-2-thienyl)-
(4-(trimethylsilyl)ethynylphenyl)acetylene (10b) by the pro-
cedure described for the synthesis of 5b, except that NEt3 was
used instead of Et2NH. After the solvent was removed in
vacuo, the residue extracted with CH2Cl2/H2O (1:1). The
organic layer was pumped dry and the residue chromato-
graphed using CH2Cl2/hexane (1:4) as eluent. The yellow
powdery 10b was isolated in 77% yield from the second band.
1H NMR (CDCl3): δ 7.81 (d, 1 H, 3J H-H ) 4.2 Hz, SCCH), 7.51
4
CHd), 5.37 (t, 1 H, J H-P ) 2.4 Hz, RudCdCH), 5.29 (s, 5 H,
C5H5). 31P{H} NMR (CDCl3): δ 42.7 (s, 2 P, RuP), -145
1
(heptet, 1 P, J P-F ) 702 Hz, PF6). Anal. Calcd for C55H44F6-
NO2P3SRu: C, 60.55; H, 4.06; N, 1.28. Found: C, 60.11; H,
4.50; N, 1.01.
Ru (CtCC6H5-(E)-CHdCH-th -NO2)(P P h 3)2(η5-C5H5) (7).
A solution of Et3N (2 mL) in 50 mL of CH2Cl2 was added to a
flask containing 6 (280 mg, 0.26 mmol), and the resulting
solution was stirred at room temperature for 10 min. After
the solvent was removed, the residue was chromatographed
using THF/hexane (1:4) as eluent to afford the dark purple
powdery 7 in 78% yield (190 mg). IR (KBr, cm-1): 2061 (s),
ν(CtC). 13C NMR (CD2Cl2): δ 151.8 (s, dCS), 148.3 (s, dCS),
138.8 (t, J C-P ) 21.6, Cipso of PPh3), 135.9 (s, dCS), 135.8 (s,
dCS), 134.3 (s, dCH), 133.8 (t, J C-P ) 4.7, Cortho of PPh3), 130.8
(s, dCH), 129.9 (s, dCH), 128.6 (s, Cpara of PPh3), 127.3 (t, J C-P
) 4.1, Cmeta of PPh3), 126.3 (t, J C-P ) 24.6, Ru-CtC), 126.3
(s, dCH), 124.0 (s, dCH), 117.5 (s, dCH), 116.3 (s, RuCtC),
85.4 (s, C5H5). Anal. Calcd for C55H43NO2P2SRu: C, 69.90;
H, 4.59; N, 1.48. Found: C, 69.82; H, 4.44; N, 1.42.
3
(d, 2 H, J H-H ) 8.4 Hz, C6H4), 7.30 (d, 2 H, C6H4), 7.14 (d, 1
H, SCCH), 0.24 (s, 9 H, CH3).
Compound 10b was converted to 10 by the same procedures
as employed for the synthesis of 5 from 5b. The yellow
powdery 10 was eluted by CH2Cl2/hexane (1:1) and isolated
in 64% yield from the first band. MS (EI): m/e 253 (M+). 1H
NMR (CDCl3): δ 7.81 (d, 1 H, 3J H-H ) 4.2 Hz, SCCH), 7.48 (s,
4 H, C6H4), 7.14 (d, 1 H, SCCH), 3.20 (s, 1 H, CHt). Anal.
Calcd for C14H7NO2S: C, 66.39; H, 2.79; N, 5.53. Found: C,
66.19; H, 2.75; N, 5.30.
Ru (CtCC6H5CtC-th -NO2)(P P h 3)2(η5-C5H5) (11). Com-
pound 11 was synthesized by the same procedures as employed
for 9, except that 10 was utilized instead of 8. The crude
product was chromatographed using THF/hexane (1:4) as
eluent. The dark brown 11 was isolated in 64% yield from
the second band. MS (FAB): m/e 943 (M+). IR (KBr, cm-1):
2195 (m), 2061 (s), ν(CtC). Anal. Calcd for C55H41NO2P2-
SRu: C, 70.05; H, 4.38; N, 1.49. Found: C, 70.10; H, 4.30; N,
1.25.
(E)-1-(5-Eth yn yl-2-th ien yl)-2-(4-n itr op h en yl)eth ylen e
(8). A solution of NaOMe, prepared in situ from Na (303 mg,
13.2 mmol) and MeOH (30 mL), was added to a mixture of 1a
(1.25 g, 6.00 mmol) and [Ph3PCH2C6H4NO2-4][Br] (2.63 g, 5.50
mmol) in 40 mL of MeOH, and the resulting mixture was
stirred at room temperature for 2.5 h. A 20 mL volume of
H2O was added and the solution filtered. The solid was
collected and chromatographed using CH2Cl2/hexane (1:3) as
eluent. The orange yellow powdery 8 was isolated in 45% yield
(630 mg). MS (EI): m/e 255 (M+). 1H NMR (CDCl3): δ 8.17
2-(2-(5-Eth yn yl-2-th ien yl)-(E)-eth en yl)-5-(2-(4-n itr oph en -
yl-(E)-eth en yl)th iop h en e (12). A solution of NaOMe, pre-
pared in situ from Na (248 mg, 10.8 mmol) and MeOH (30
mL), was added to a mixture of 3a (950 mg, 3.00 mmol) and
[Ph3PCH2C6H4NO2-4][Br] (1.44 g, 3.01 mmol) in 25 mL of
MeOH. The resulting mixture was stirred at room tempera-
ture for 2 h and then kept in a refrigerator overnight. The
purple-red precipitate formed was collected by filtration and
washed with cold MeOH (2 × 3 mL) and subsequently dried
to afford 12 in 49% yield (530 mg). 1H NMR (CDCl3): δ 8.19
3
(d, 2 H, J H-H ) 8.9 Hz, C6H4), 7.54 (d, 2 H, C6H4), 7.26 (d, 1
3
3
H, J H-H ) 16.1 Hz, CHd), 7.17 (d, 1 H, J H-H ) 3.9 Hz,
SCCH), 6.99 (d, 1 H, SCCH), 6.90 (d, 1 H, CHd), 3.43 (s, 1 H,
CHt). Anal. Calcd for C14H9NO2S: C, 65.87; H, 3.55; N, 5.49.
Found: C, 65.84; H, 3.44; N, 5.66.
3
Ru (CtC-th -(E)-CHdCHC6H4NO2)(P P h 3)2(η5-C5H5) (9).
To a mixture of RuCl(PPh3)2(η5-C5H5) (726 mg, 1.00 mmol) and
8 (306 mg, 1.20 mmol) was added 25 mL of MeOH. The
resulting mixture was refluxed for 2 h and then allowed to
cool to room temperature. A solution of NaOMe, prepared in
situ from Na (28 mg, 1.22 mmol) and MeOH (5 mL), was
added, and the resulting mixture was stirred at room tem-
perature for 5 min. The volume of the solution was reduced
to 10 mL and filtered. The solid was washed with cold MeOH
(2 × 3 mL) and dried to provide the dark purple powdery 9 in
71% yield (670 mg). MS (FAB): m/e 947 (M+, 104Ru). IR (KBr,
cm-1): 2044 (vs), ν(CtC); 1614 (m), ν(CdC). 13C NMR (CD2-
(d, 2 H, J H-H ) 8.7 Hz, C6H4), 7.55 (d, 2 H, C6H4), 7.30 (d, 1
3
3
H, J H-H ) 16.0 Hz, CHd), 7.14 (d, 1 H, J H-H ) 3.7 Hz,
3
SCCH), 7.03 (d, 1 H, J H-H ) 3.7 Hz, SCCH), 6.96 (d, 1 H,
3J H-H ) 3.7 Hz, SCCH), 6.96 (s, 2 H, CHd), 6.89 (d, 1 H, 3J H-H
3
) 3.7 Hz, SCCH), 6.88 (d, 1 H, J H-H ) 16.0 Hz, CHd), 3.41
(s, 1 H, CHt). Anal. Calcd for C20H13NO2S2: C, 66.09; H,
3.61; N, 3.85. Found: C, 65.97; H, 3.55; N, 3.73.
Ru (CtC-th -(E)-CHdCH-th -CHdCH-th -NO2)(P P h 3)2(η5-
C5H5) (13). Complex 13 was synthesized in the same manner
as 2, except that 12 was used instead of 1. A dark purple
powdery 13 was isolated in 72% yield. MS (FAB): m/e 1055
(M+, 104Ru). IR (KBr, cm-1): 2046 (s). 13C NMR (CD2Cl2): δ

Ruthenium σ-Acetylides
Organometallics, Vol. 17, No. 11, 1998 2191
146.3 (s, CNO2), 144.7 (s, CCCCNO2), 143.8 (s, dCS), 139.2
(s, dCS), 138.5 (t, J C-P ) 21.2, Cipso of PPh3), 136.0 (s, dCS),
133.7 (t, J C-P ) 5.2, Cortho of PPh3), 132.5 (t, J C-P ) 24.4, Ru-
CtC), 132.0 (s, dCS), 129.6 (s, dCH), 128.5 (s, Cpara of PPh3),
127.8 (s, dCH), 127.3 (t, J C-P ) 4.7, Cmeta of PPh3), 126.4 (s,
dCH), 126.3 (s, C6H4), 126.0 (s, dCH), 125.8 (s, dCH), 124.8
(s, dCH), 124.2 (s, C6H4), 123.9 (s, dCH), 117.8 (s, dCH), 108.1
(s, RuCtC), 85.5 (s, C5H5). Anal. Calcd for C61H47NO2P2S2-
Ru: C, 69.57; H, 4.50; N, 1.33. Found: C, 69.22; H, 4.83; N,
1.30.
0.070 mL (1.11 mmol) of MeI. The solution was stirred at room
temperature in the dark for 10 h. After removal of the solvent,
the residue was dissolved in CH2Cl2 and filtered. The filtrate
was pumped dry and the residue recrystallized from CH2Cl2/
hexane to give 18 as a dark blue powder (340 mg, 58%). MS
(FAB): m/e 916 (M+ - PF6, 102Ru). IR (KBr, cm-1): 2032 (s),
ν(CtC). Anal. Calcd for C55H46F6NP3SRu: C, 62.26; H, 4.37;
N, 1.32. Found: C, 61.90; H, 4.25; N, 1.24.
(5-Eth yn yl-2-th ien yl)(4-p yr id yl)a cetylen e (19). To a
mixture of 5-bromo-2-iodothiophene (3.90 g, 13.5 mmol),
ethynylpyridine (1.40 g, 13.5 mmol), PdCl2(PPh3)2 (170 mg,
0.24 mmol), and CuI (50 mg, 0.26 mmol) was added 50 mL of
Et2NH, and the resulting mixture was stirred at room tem-
perature for 20 h. The solvent was removed under vacuum
and the residue extracted with CH2Cl2/H2O (3:5). The organic
layer was pumped dry and the residue chromatographed using
THF/hexane as eluent. The tan powdery (5-bromo-2-thienyl)-
(4-pyridyl)acetylene (19a ) was isolated in 75% yield (2.11 g).
(E)-N-(4-Eth yn ylph en yl)-C-(5-n itr o-2-th ien yl)im in e (14).
A 50 mL amount of benzene was added to a flask containing
a mixture of 5-nitro-2-thiophenecarboxaldehyde (157 mg, 1.00
mmol) and 4-ethynylaniline (150 mg, 1.28 mmol) and equipped
with a Dean-Stark trap. The solution was refluxed for ca. 3
h. The solvent was removed and the residue chromatographed.
The orange powdery 14 was eluted by CH2Cl2/hexane (1:5) and
isolated in 78% yield (195 mg). MS (EI): m/e 255 ((M - 1)+).
1H NMR (acetone-d6): δ 8.51 (s, 1 H, NdCH), 7.90 (d, 1 H,
3
1H NMR (acetone-d6): δ 8.61 (d, 2 H, J H-H ) 6.0 Hz, NCH),
3
3
3J H-H ) 4.1 Hz, SCCH), 7.52 (d, 2 H, J H-H ) 8.6 Hz, C6H4),
7.44 (d, 2 H, NCHCH), 7.27 (d, 1 H, J H-H ) 3.9 Hz, SCCH),
7.37 (d, 1 H, SCCH), 7.19 (d, 2 H, C6H4). Anal. Calcd for C13
-
7.20 (d, 1 H, SCCH).
H8N2O2S: C, 60.93; H, 3.15; N, 10.93. Found: C, 60.76; H,
3.03; N, 10.82.
Compound 19a was converted to (4-pyridyl)(5-(trimethylsi-
lyl)ethynyl-2-thienyl)acetylene (19b) by the same procedure
as employed for the synthesis of 5b from 5a , except that the
reaction proceeded at room temperature. The yellow powdery
19b was isolated in 73% yield. 1H NMR (acetone-d6): δ 8.67
(d, 2 H, 3J H-H ) 6.0 Hz, NCH), 7.46 (d, 2 H, NCHCH), 7.35 (d,
Ru (CtCC6H5NdC(H)-th -NO2)(P P h 3)2(η5-C5H5) (15). Com-
pound 15 was synthesized by the same procedure as employed
for 7, except that 14 was utilized instead of 5. After the solvent
was removed, the residue chromatographed using CH2Cl2/
hexane (1:1) as eluent to afford the blue powdery 15 in 57%
yield. Anal. Calcd for C54H42N2O2P2SRu: C, 68.56; H, 4.48;
N, 2.96. Found: C, 68.62; H, 4.38; N, 2.92.
3
1 H, J H-H ) 3.6 Hz, SCCH), 7.26 (d, 1 H, SCCH), 0.23 (s, 9
H, CH3).
A solution of KOH (420 mg, 7.50 mmol) in 30 mL of MeOH
was slowly added to a solution of 19b (1.91 g, 6.80 mmol) in
50 mL of MeOH. The mixture was stirred at room tempera-
ture for 1 h. The solvent was removed in vacuo and the residue
extracted with CH2Cl2/H2O (3:5). The organic layer was
chromatographed using CH2Cl2 as eluent. The compound 19
was obtained as an off-white powder in 70% yield (990 mg).
MS (EI): m/e 209 (M+). 1H NMR (acetone-d6): δ 8.62 (d, 2 H,
3J H-H ) 6.3 Hz, NCH), 7.46 (d, 2 H, NCHCH), 7.36 (d, 1 H,
3J H-H ) 3.9 Hz, SCCH), 7.31 (d, 1 H, SCCH), 4.15 (s, 1 H,
CHt). Anal. Calcd for C13H7NS: C, 74.61; H, 3.37; N, 6.69.
Found: C, 74.44; H, 3.23; N, 6.50.
R u (CtC-t h -CtCC5H 4N)(P P h 3)2(η5-C5H 5) (20). Com-
pound 20 was synthesized by the same procedure as employed
for 7, except that 19 was utilized instead of 5 and THF/hexane
(2:3) used as eluent for chromatography. An orange yellow
powdery 20 was isolated in 61% yield. MS (FAB): m/e 899
(M+, 102Ru). IR (KBr, cm-1): 2194 (m), 2047 (s), ν(CtC). Anal.
Calcd for C54H41NP2SRu: C, 72.14; H, 4.60; N, 1.56. Found:
C, 71.89; H, 4.35; N, 1.42.
(E)-1-(5-Eth yn yl-2-th ien yl)-2-(4-p yr id yl)eth ylen e (16).
A 10 mL amount of Ac2O was added to a mixture of 4-picoline
(1.12 mL, 11.5 mmol) and 5-bromo-2-thiophenecarboxaldehyde
(2.00 g, 10.5 mmol), and the resulting solution was heated at
140 °C for 48 h. After addition of 200 mL of iced water, the
solution was extracted with CH2Cl2. The organic layer was
dried over MgSO4, filtered, and pumped dry. The residue was
chromatographed using THF/hexane (2:3) as eluent to afford
the yellow powdery (E)-1-(5-bromo-2-thienyl)-2-(4-pyridyl)-
ethylene (16a ) in 76% yield (980 mg). 1H NMR (acetone-d6):
3
3
δ 8.51 (d, 2 H, J H-H ) 6.3 Hz, NCH), 7.61 (d, 1 H, J H-H
)
)
3
16.2 Hz, CHd), 7.46 (d, 2 H, NCHCH), 7.13 (d, 1 H, J H-H
3.9 Hz, SCCH), 7.09 (d, 1 H, SCCH), 6.90 (d, 1 H, CHd).
Compound 16a was converted to (E)-1-(5-(trimethylsilyl)-
ethynyl-2-thienyl)-2-(4-pyridyl)ethylene (16b) by the same
procedure as employed for the synthesis of 5b. Bright yellow
powdery 16b was isolated in 81% yield. 1H NMR (acetone-
d6): δ 8.53 (br, 2 H, NCH), 7.64 (d, 1 H, 3J H-H ) 16.2 Hz, CHd),
3
7.47 (br, 2 H, NCHCH), 7.22 (d, 1 H, J H-H ) 3.9 Hz, SCCH),
[Ru (CtC-th -CtCC5H4NMe)(P P h 3)2(η5-C5H5)][P F 6] (21).
Compound 21 was synthesized by the same procedure as
employed for 18, except that 20 was utilized instead of 17. A
dark purple powdery 21 was isolated in 48% yield. MS
(FAB): m/e 914 (M+ - PF6, 102Ru). IR (KBr, cm-1): 2160 (m),
2025 (s), ν(CtC). Anal. Calcd for C55H44F6NP3SRu: C, 62.38;
H, 4.19; N, 1.32. Found: C, 62.00; H, 3.98; N, 1.10.
7.19 (d, 1 H, SCCH), 6.98 (d, 1 H, CHd), 0.23 (s, 9 H, CH3).
Compound 16 was synthesized from 16b by the same
procedures as employed for the synthesis of 5 from 5b. The
crude product was chromatographed using THF/hexane (1:1)
as eluent to afford 16 as a light tan powder in 56% yield. MS
(EI): m/e 211 (M+). 1H NMR (acetone-d6): δ 8.52 (d, 2 H, 3J H-H
) 6.0 Hz, NCH), 7.65 (d, 1 H, 3J H-H ) 16.5 Hz, CHd), 7.48 (d,
3
2 H, NCHCH), 7.26 (d, 1 H, J H-H ) 3.9 Hz, SCCH), 7.20 (d,
(E)-1-(5-E t h yn yl-2-t h ien yl)-2-(5-n it r o-2-t h ien yl)et h yl-
en e (22). Triethylamine (100 mL) and (trimethylsilyl)acet-
ylene (0.85 mL, 6.0 mmol) were added to a flask containing a
mixture of (E)-1-(5-bromo-2-thienyl)-2-(5-nitro-2-thienyl)eth-
ylene (1.42 g, 5.0 mmol), PdCl2(PPh3)2 (70 mg, 0.10 mmol), and
CuI (10 mg, 0.050 mmol). The resulting mixture was then
stirred at room temperature for 16 h. The solvent was
removed in vacuo and the residue extracted with Et2O and
H2O. The organic layer was collected, dried over MgSO4, and
passed through a short Al2O3 column. Removal of the solvent
gave red-brown crystalline (E)-1-(5-nitro-2-thienyl)-2-(5-(tri-
methylsilyl)ethynyl-2-thienyl)ethylene (22a ). MS (EI): m/e
1 H, SCCH), 6.99 (d, 1 H, CHd), 4.10 (s, 1 H, CHt). Anal.
Calcd for C13H9NS: C, 79.90; H, 4.29; N, 6.63. Found: C,
79.82; H, 4.19; N, 6.53.
R u (CtC-t h -(E)-CH dCH C5H 4N)(P P h 3)2(η5-C5H 5) (17).
Compound 17 was synthesized by the same procedures as
employed for 7, except that 16 was utilized instead of 5. After
the solvent was removed, the residue chromatographed using
THF/hexane (3:2) as eluent to afford the dark red powdery 17
in 75% yield. MS (FAB): m/e 901 (M+, 102Ru). IR (KBr, cm-1):
2044 (s), ν(CtC). Anal. Calcd for C54H43NP2SRu: C, 71.98;
H, 4.81; N, 1.55. Found: C, 71.46; H, 4.96; N, 1.22.
[R u (CtC-t h -(E)-CH dCH C5H 4NMe)(P P h 3)2(η5-C5H 5)]-
[P F 6] (18). To a flask containing 17 (500 mg, 0.55 mmol) and
3
332 (M+). 1H NMR (CDCl3): δ 7.80 (d, 1 H, J H-H ) 4.3 Hz,
3
SCCH), 7.14 (d, 1 H, J H-H ) 15.8 Hz, CHd), 7.11 (d, 1 H,
Tl+PF6 (290 mg, 0.83 mmol) was added 50 mL of THF and
3J H-H ) 3.8 Hz, SCCH), 6.99 (d, 1 H, J H-H ) 3.8 Hz, SCCH),
-
3

2192 Organometallics, Vol. 17, No. 11, 1998
Wu et al.
Ta ble 1. Cr ysta l Da ta for Com p ou n d s 7 a n d 26
3
6.95 (d, 1 H, J H-H ) 4.3 Hz, SCCH), 6.86 (d, 1 H, CHd), 0.24
(s, 9 H, CH3).
7
26
Compound 22a was treated directly with a solution of KOH
(0.28 g, 5.0 mmol) in 50 mL of MeOH and 5 mL of H2O. The
solution was stirred at room temperature for 1 h, and a
mixture of CH2Cl2 (150 mL) and H2O (150 mL) was added.
The aqueous layer was further extracted with CH2Cl2 (2 × 50
mL). All organic extracts were combined and dried over
MgSO4. The solution was filtered and the filtrate evaporated
to dryness. The residue was chromatographed using ethyl
acetate/hexane (1:4) as eluent to afford 22 as a red-brown
powder in 85% yield (1.11 g). MS (EI): m/e 260 (M+). 1H NMR
chem formula
fw
cryst size, mm
cryst system
space group
a, Å
C
55H43NO2P2SRu
C51H38N2P2SRu
873.95
945.03
0.38 × 0.25 × 0.25 0.11 × 0.13 × 0.38
monoclinic
P21/n
orthorhombic
Pna21
25.102(4)
16.726(2)
9.917(2)
11.111(1)
19.121(2)
21.230(3)
100.25(1)
4438.4(9)
4
+20
1944
0.7107
1.414
5.042
1.00-0.97
50
-13 to 12, 0 to 22, 0 to 29, 0 to 19,
0 to 25 0 to 11
8222 3881
7791
b, Å
c, Å
â, deg
V, Å3
4164(1)
4
+20
1792
0.7107
1.394
5.290
1.00-0.95
50
Z
T, °C
F(000)
3
(CDCl3): δ 7.81 (d, 1 H, J H-H ) 4.3 Hz, SCCH), 7.17 (d, 1 H,
3
3J H-H ) 3.8 Hz, SCCH), 7.15 (d, 1 H, J H-H ) 15.9 Hz, CHd),
3
3
7.00 (d, 1 H, J H-H ) 3.8 Hz, SCCH), 6.96 (d, 1 H, J H-H ) 4.3
Hz, SCCH), 6.89 (d, 1 H, CHd), 3.45 (s, 1 H, CHt). Anal.
Calcd for C13H7NS: C, 74.61; H, 3.37; N, 6.69. Found: C,
74.44; H, 3.23; N, 6.50. Anal. Calcd for C12H7NO2S2: C, 55.16;
H, 2.70; N, 5.36. Found: C, 54.98; H, 2.60; N, 5.27.
λ(Mo KR), Å
F
calc, g cm-3
µ, cm-1
transm coeff
2θmax, deg
h, k, l range
R u (CtC-t h -(E)-CHdCH-t h -NO2)(P P h 3)2(η5-C5H5) (23).
To a mixture of RuCl(PPh3)2(η5-C5H5) (556 mg, 0.77 mmol),
tot. reflns
unique reflns
-
NH4+PF6 (150 mg, 0.92 mmol), and 22 (200 mg, 0.77 mmol)
3881
was added 50 mL of CH2Cl2 and 20 mL of MeOH. The
resulting mixture was stirred at room temperature for 18 h.
The solvent was removed under vacuum and the residue
extracted with 10 mL of CH2Cl2. The CH2Cl2 solution was
filtered through Celite and the filtrate evaporated to dryness.
To the residue was added CH2Cl2 (50 mL) and NEt3 (10 mL),
and the solution was stirred at room temperature for 20 min.
The solvent was removed under vacuum and the residue
chromatographed using CH2Cl2 as eluent to afford dark purple
powdery 23 in 74% yield (536 mg). MS (FAB): m/e 951 (M+,
102Ru). IR (KBr, cm-1): 2040 (s), ν(CtC). 13C NMR (CD2Cl2):
δ 151.9 (s, dCS), 147.5 (s, dCS), 138.5 (t, J C-P ) 21.6, Cipso of
PPh3), 138.2 (t, J C-P ) 24.1, Ru-CtC), 134.7 (s, dCS), 134.2
(s, dCS), 133.7 (t, J C-P ) 4.7, Cortho of PPh3), 130.7 (s, dCH),
130.1 (s, dCH), 128.7 (s, Cpara of PPh3), 127.6 (s, dCH), 127.4
(t, J C-P ) 4.1, Cmeta of PPh3), 126.3 (s, dCH), 123.4 (s, dCH),
115.8 (s, dCH), 109.1 (s, RuCtC), 85.7 (s, C5H5). Anal. Calcd
for C53H41NO2P2S2Ru: C, 66.93; H, 4.34; N, 1.43. Found: C,
66.73; H, 4.29; N, 1.40.
obsd reflns (I > nσ(I)) 5103 (n ) 2.5)
2737 (n ) 2.0)
refined params
559
515
Ra
0.040
0.046
1.04
0.034
0.035
1.05
b
Rw
GOF(F2)c
a
b
2
R ) ∑||Fo| - |Fc||/∑|Fo|. Rw ) [∑w(|Fo| - |Fc|)2/∑w|Fo| ]1/2; w
) 1/[σ2(Fo) + kFo2] where, k ) 0.0001 for 7 and 0.0003 for 26. c GOF
) [∑w(|Fo| - |Fc|)2/(n - p)]1/2, where n ) no. of observed reflections
and p ) number of variables.
in 83% yield (350 mg). MS (FAB): m/e 874 (M+, 102Ru). IR
(KBr, cm-1): 2214 (m), ν(CtN), 2017 (s), ν(CtC). 13C NMR
(CD2Cl2): δ 161.7 (t, J C-P ) 23.8, Ru-CtC), 148.5 (s, dCH),
144.4 (s, dCS), 141.9 (s, dCH), 137.9 (t, J C-P ) 21.6, Cipso of
PPh3), 133.6 (t, J C-P ) 4.7, Cortho of PPh3), 129.5 (s, dCS), 129.0
(s, Cpara of PPh3), 127.6 (t, J C-P ) 4.1, Cmeta of PPh3), 127.2 (s,
dCH), 116.3 (s, CN), 115.4 (s, CN), 114.5 (s, RuCtC), 86.4 (s,
C5H5), 68.4 (s, C(CN)2). Anal. Calcd for C51H38N2P2SRu: C,
70.09; H, 4.38; N, 3.21. Found: C, 69.67; H, 4.41; N, 3.15.
R u (CtC-t h -(E)-CH dCH -t h -(E)-CH d(CN)2)(P P h 3)2(η5-
C5H5) (27). Complex 27 was synthesized by the same proce-
dures as employed for 26, except that 4 was utilized instead
of 2 and the reaction time was 5 h. Dark black powdery 27
was isolated in 57% yield. MS (FAB): m/e 984 (M+, 104Ru).
IR (KBr, cm-1): 2219 (m), ν(CtN); 2038 (s), ν(CtC). 13C NMR
(CD2Cl2): δ 156.2 (s, dCS), 149.7 (s, dCH), 140.7 (s, dCH),
139.5 (t, J C-P ) 23.9, Ru-CtC), 138.5 (t, J C-P ) 21.6, Cipso of
PPh3), 135.1 (s, dCS), 134.5 (s, dCS), 133.7 (t, J C-P ) 4.7, Cortho
of PPh3), 132.5 (s, dCS), 131.2 (s, dCH), 128.7 (s, Cpara of PPh3),
128.6 (s, dCH), 127.4 (t, J C-P ) 4.1, Cmeta of PPh3), 126.6 (s,
dCH), 125.7 (s, dCH), 115.8 (s, dCH), 115.0 (s, CN), 114.2 (s,
CN), 109.5 (s, RuCtC), 85.7 (s, C5H5), 73.7 (s, C(CN)2). Anal.
Calcd for C57H42N2P2S2Ru: C, 69.71; H, 4.31; N, 2.85. Found:
C, 69.61; H, 4.32; N, 2.76.
Cr ysta llogr a p h ic Stu d ies. Crystals of 7 and 26 were
grown by slow diffusion of hexane into a concentrated solution
of complex 7 in CH2Cl2. Crystals were mounted on a glass
fiber covered with epoxy. Diffraction measurements were
made on an Enraf-Nonious CAD4 diffractometer by using
graphite-monochromated Mo KR radiation (λ ) 0.7107 Å) with
the θ-2θ scan mode. Unit cells were determined by centering
25 reflections in the suitable 2θ range. Other relevant
experimental details are listed in Table 1. The structure was
solved by direct methods using NRCVAX18 and refined using
full-matrix least-squares techniques. All non-hydrogen atoms
were refined with anisotropic displacement parameters, and
2-Eth yn yl-5-((5-n itr o-2-th ien yl)eth yn yl)th iop h en e (24).
To a mixture of 2,5-diethynylthiophene (3.81 g, 28.9 mmol),
2-bromo-5-nitrothiophene (2.00 g, 9.62 mmol), PdCl2(PPh3)2 (80
mg, 0.11 mmol), and CuI (40 mg, 0.21 mmol) was added 150
mL of iPr2NH2, and the resulting mixture was stirred at room
temperature for 18 h. The solvent was removed under vacuum
and the residue chromatographed using CH2Cl2/hexane (1:4)
as eluent. Orange-brown powdery 24 was isolated in 64% yield
(1.60 g) from the first band. MS (EI): m/e 259 (M+). 1H NMR
3
(CDCl3): δ 7.81 (d, 1 H, J H-H ) 4.3 Hz, SCCH), 7.20 (d, 1 H,
3
3J H-H ) 3.9 Hz, SCCH), 7.17 (d, 1 H, J H-H ) 3.9 Hz, SCCH),
3
7.15 (d, 1 H, J H-H ) 4.3 Hz, SCCH), 3.42 (s, 1 H, CHt). 2,5-
Bis(5-nitro-2-thienyl)ethynylthiophene was also obtained in
19% yield (700 mg). MS (EI): m/e 387 (M+). 1H NMR
3
(CDCl3): δ 7.82 (d, 2 H, J H-H ) 4.3 Hz, SCCH), 7.17 (d, 1 H,
SCCH). Anal. Calcd for C12H5NO2S2: C, 55.58; H, 1.94; N,
5.40. Found: C, 55.66; H, 1.99; N, 5.23.
Ru (CtC-th -CtC-th -NO2)(P P h 3)2(η5-C5H5) (25). Complex
25 was synthesized by the same procedure as employed for
23, except that 24 was utilized instead of 22. Purple powdery
25 was isolated in 69% yield. MS (FAB): m/e 949 (M+, 102Ru).
IR (KBr, cm-1): 2174 (m), 2040 (s), ν(CtC). Anal. Calcd for
C
53H39NO2P2S2Ru: C, 67.08; H, 4.14; N, 1.48. Found: C,
67.21; H, 4.35; N, 1.41.
Ru (CtC-th -CHdC(CN)2)(P P h 3)2(η5-C5H5) (26). To a flask
containing 2 (400 mg, 0.48 mmol) and CH2(CN)2 (40 mg, 0.60
mmol) was added 100 mL of ethanol and 0.10 mL of piperidine.
The solution was refluxed for 2.5 h and the solvent removed
under vacuum. The residue was chromatographed using CH2-
Cl2/EtOAc as eluent. The dark green powdery 26 was isolated
(18) Gabe, E. J .; LePage, Y.; Charland, J . P.; Lee, F. L.; White, P.
S. J . Appl. Crystallogr. 1989, 22, 384.

Ruthenium σ-Acetylides
Organometallics, Vol. 17, No. 11, 1998 2193
Ta ble 2. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) for Com p lexes 7 a n d 26
Ch a r t 1
7
26
Distances
Ru-C1
2.215(5)
2.213(8)
2.246(7)
2.263(7)
2.235(7)
2.216(9)
1.974(7)
2.293(2)
2.299(2)
1.23(1)
1.42(1)
1.37(1)
1.39(1)
1.40(1)
1.39(1)
1.37(2)
Ru-C2
2.229(5)
2.231(5)
2.234(5)
2.228(5)
2.013(5)
2.292(1)
2.282(1)
1.190(7)
1.438(7)
1.394(8)
1.376(8)
1.402(8)
1.379(8)
1.369(8)
1.391(8)
Ru-C3
Ru-C4
Ru-C5
Ru-C6
Ru-P1
Ru-P2
C6-C7
C7-C8
C8-C9
C9-C10
C10-C11
C11-C12
C12-C13
C13-C8
C13-C14
C13-C15
C11-C14
C14-C15
C15-C16
C14-N14
C15-N15
C16-C17
C17-C18
C18-C19
S-C8
1.42(2)
1.43(1)
1.476(8)
1.298(9)
1.471(9)
this HRS experiment was shifted to a longer wavelength at
1560 nm to block the TPA process and obtain the correct â
value. The experimental setup of long wavelength HRS
experiment was the same as that of 1064 nm HRS experi-
ment19a,19b except that a 1064 nm half-wave plate and a 532
nm interference filter were replaced by an achromatic half-
wave plate and a 780 nm interference filter, respectively. To
ensure no multiple photon absorption-induced fluorescence
(MPAIF) occurs in the vicinity of second harmonic wavelength,
a 820 nm interference filter was put in front on photomultiplier
to check the MPAIF signal. Except for 15, the MPAIF was
found to be negligible. The errors in the measured â values
were estimated to be (15% on the basis of the largest deviation
1.14(2)
1.12(1)
1.343(9)
1.29(1)
1.30(1)
1.745(8)
1.730(8)
S-C11
S-C19
1.716(7)
1.697(6)
1.421(9)
1.22(1)
S-C16
N-C19
N-O1
N-O2
1.26(1)
2
from the least-squares fitting plot of I2ω/Iω vs the number
Angles
99.35(5)
91.4(1)
90.1(1)
174.5(4)
177.4(5)
densities of chromophores in the solution.19a
P1-Ru-P2
100.84(8)
90.4(2)
90.6(2)
173.7(6)
172.2(8)
129.0(9)
In this experiment, a solution of Disperse Red 1 (DR1) in
CH2Cl2 was used as external reference. Using the undamped
two-state model and the dispersion free â value (âo) of DR1 in
CHCl3 (âo ) 38 × 10-30 esu),20 the â value of DR1 in CHCl3
was found to be 69.2 × 10-30 esu. Considering the dependence
of the â value of a chromophore on the solvent with the
dielectric constant ꢀ (i.e., â (ꢀ - 1)/(2ꢀ + 1)),21 the â value of
DR1 in CH2Cl2 at 1560 nm was determined to be 78.8 × 10-30
esu.22
P1-Ru-C6
P2-Ru-C6
Ru-C6-C7
C6-C7-C8
C11-C12-C13
C11-C14-C15
C12-C13-C14
C12-C13-C15
C13-C14-N14
C13-C15-N15
C14-C15-C16
C16-S-C19
O1-N-O2
126.0(6)
125.4(7)
119.3(9)
178(1)
180(1)
128.6(6)
89.5(3)
125.7(7)
Resu lts a n d Discu ssion
Syn th eses a n d Ch a r a cter iza tion of Ru th en iu m
Com p lexes. Ruthenium σ-acetylides synthesized in
this study are depicted in Chart 1. Most complexes were
prepared from RuCl(PPh3)2(η5-C5H5) and the corre-
sponding terminal alkynes according to a well-known
procedure23 (eq 1). Deterioration of dicyanovinyl moiety
all hydrogen atoms were placed in idealized positions. The
selected interatomic distances and bond angles are given in
Table 2. All other crystal data for 7 and 26 are given in the
Supporting Information.
HRS Exp er im en t. An optical parametric oscillating (OPO)
laser (Continuum Mirage 500) generating 8 ns tunable laser
pulses from 400 to 2000 nm with a 10 Hz repetition rate was
used as the light source in the Hyper-Rayleigh scattering
(HRS) experiment. Recently, HRS from some molecules
excited by the 1064 nm fundamental radiation have been found
to be accompanied by the two-photon absorption (TPA) induced
fluorescence.19 Consequently, the â value determined by short
wavelength HRS experiment such as 1064 nm could be too
large.19c The fundamental wavelength of excitation laser in
(1)
(19) (a) Hsu, C. C.; Shu, C. F.; Huang, T. H.; Wang, C. H.; Lin, J .
L.; Wang, Y. K.; Zang, Y. L. Chem. Phys. Lett. 1997, 274, 466. (b) Hsu,
C. C.; Huang, T. H.; Zang, Y. L.; Lin, J . L.; Chen, Y. Y.; Lin, J . T.; Wu,
H. H.; Wang, C. H.; Kuo, C. T.; Chen, C. H. J . Appl. Phys. 1996, 80,
5996. (c) Flipse, M. C.; de J onge, R.; Woundenberg, R. H.; Marsman,
A. W.; van Walree, C. A.; J enneskens, L. W. Chem. Phys. Lett. 1995,
245, 297. (d) Hendrickx, E.; Dehu, C.; Clays, K.; Bre´das, J . L.; Persoons,
A. ACS Symp. Ser. 1995, No. 601, 82.
(20) Stadler, S.; Dietrich, R.; Bourhill, G.; Brauchle, C.; Pawlik, A.;
Grahn, W. Chem. Phys. Lett. 1995, 247, 721.
(21) Clays, K.; Persoons, A. Phys. Rev. Lett. 1991, 66, 2980.
(22) The dielectric constants (ꢀ) for CHCl3 and CH2Cl2 are 4.81 and
7.77, respectively: Dean, J . A., Ed. Handbook of Organic Chemistry;
McGraw-Hill: New York, 1987.
(23) (a) Bruce, M. I. Chem. Rev. 1991, 91, 270. (b) Bruce, M. I.;
Swincer, A. G. Adv. Organomet. Chem. 1983, 22, 59.

2194 Organometallics, Vol. 17, No. 11, 1998
Wu et al.
Sch em e 1a
a
(i) (Trimethylsilyl)acetylene, PdCl2(PPh3)2 (2%), CuI (1%), Et2NH; (ii) KOH/MeOH; (iii) Ph3PCH2(C6H4)NO2-4, MeONa (2.2
equiv); (iv) Ph3PCH2(C6H4)Br-4; NaH; (v) n-Bu4N+F-; (vi) PdCl2(PPh3)2 (2%), CuI (1%), Et3N, 25 °C, 10 h; (vii) γ-picoline, Ac2O;
(viii) PdCl2(PPh3)2 (2%), CuI (1%), Et2NH.
occurred during base treatment of vinylidenes to form
σ-acetylides, therefore, complexes 26 and 27 have to be
synthesized indirectly from 2 and 4, respectively. Ter-
minal alkynes were synthesized as described in Scheme
1. Sonogashira coupling24 and Wittig reaction25 were
used to construct alkyne and alkene entities, respec-
tively. Although the traditional Wittig reaction of
triphenyl phosphorane frequently resulted in formation
of both E and Z isomers, no attempt was made to
separate the two until terminal alkynes were intro-
duced. At the end we were able to isolate only the E
isomers which possessed characteristic coupling con-
stants (ca. 16 Hz) between the two trans olefinic protons.
The E conformation of alkene moiety was preserved in
the corresponding ruthenium σ-acetylides on the basis
of coupling constants for olefinic protons (Table 3) and
a single-crystal X-ray structural determination on 7
(vide infra). The first step in eq 1 likely provides a
vinylidene intermediate,23 although no attempt was
made to isolate these intermediates in all of reactions
except for 6. The â-H atoms of complex 6 has charac-
teristic chemical shifts at ca. 5.37 ppm and a small
coupling (ca. 2.4 Hz) to two equivalent phosphorus
atoms. The chemical shifts of phosphine ligands also
have a more significant upfield shift (ca. 7 ppm) than
those of the corresponding σ-acetylide complexes in the
31P{H} NMR spectra. The chemical shifts of the Câ
carbons (108.1-116.3 ppm) of the σ-acetylide complexes
(RusCRtCâ) in the 13C{H} NMR spectra are insensitive
to changes in acetylide ligands, whereas those of CR
(with a coupling to two equivalent phosphorus atoms)
appear to be more informative. In general, a stronger
electron acceptor results in downfield shift of δ(CR), and
such an effect is more prominent for complexes with a
shorter conjugation chain. For instance, complexes
RusCRtCâ-thdth-X exhibit δ(CR) at 130.9, 135.6, 138.2,
and 139.5 ppm for X ) H, CHO, NO2, and CHdC(CN)2,
respectively, while complexes RusCRtCâ-th-X have
δ(CR) at 145.8, 154.5, and 161.7 ppm for X ) CHO, NO2,
and CHdC(CN)2, respectively. The larger upfield shift
of CR in complexes with shorter conjugation chain
implies that there is more contribution of a vinylidene
form in the former. Another characteristic feature of
σ-acetylide complexes is the existence of a ν(CtC)
stretching (2061-2017 cm-1) in the infrared spectra.
Op tica l Absor p tion Sp ectr a . Table 4 illustrates
the optical absorption spectra of the σ-acetylide com-
plexes in CH2Cl2. A very prominent feature in these
complexes is the existence of a fairly intense low-lying
charge-transfer band, indicating the indispensable roles
of both ruthenium moiety and the electron acceptor. For
instance, upon replacement of CpRu(PPh3)2 of 23, 25,
and 27 with H, the resulting terminal alkyne exhibits
only a π-π* transition at much shorter wavelength (λmax
) 386, 403, and 474 nm, respectively) (Figure 1). The
thiophene moiety can provide effective conjugation
compared with benzenoid moieties,26 and the important
role of thiophene moiety in lowering the energy of the
charge-transfer transition is also evident, i.e., λmax (524
nm) of A7 > λmax (460 nm) of D,8a λmax (526 nm) of 7 >
λ
max (476 nm) of B,8b
λmax (516 nm) of 9 > λmax (476 nm)
of B, and λmax (548 nm) of 15 > λmax (496 nm) of C.8b
The variation of λmax for 7 (526 nm), 9 (516 nm), and 13
(532 nm) appears to be in agreement with a recent
report27 that placement of thiophene at the acceptor end
of the molecule led to a more effective charge transfer.
(24) Campbell, I. B. In Organocopper Reagents; Tilor, R. J . K., Ed.;
Oxford University Press: Oxford, U.K., 1994; Chapter 10.
(25) Cadogan, J . I. G., Ed. Organophosphorus Reagents in Organic
Synthesis; Academic Press: New York, 1979.
(26) Morley, J . O.; Push, D. J . Chem. Soc., Faraday Trans. 1991,
87, 3021.
(27) Varanasi, P. R.; J en, A. K. Y.; Chandrasekhar, J .; Namboothiri,
I. N. N.; Rathna, A. J . Am. Chem. Soc. 1996, 118, 12443.

Ruthenium σ-Acetylides
Organometallics, Vol. 17, No. 11, 1998 2195
Ta ble 3. 1H a n d 31P {H} NMR Sp ectr a l Da ta for th e Com p ou n d s
δ (ppm)a,b (J (Hz))
compd
δ (ppm)a,c (J (Hz))
2
4
9.63 (s, 1 H, CHO), 7.52 (d, 1 H, J ) 3.9, SCCH), .41-7.08 (m, 30 H, C6H5), 6.59 (d, 1 H, SCCH), 4.36
(s, 5 H, C5H5)
9.79 (s, 1 H, CHO), 7.59 (d, 1 H, J ) 3.8, SCCH), 7.45-7.07 (m, 31 H, Ph and CHd), 7.02 (d, 1 H, J )
3.8, SCCH), 6.89 (d, 1 H, J ) 3.8, SCCH), 6.75 (d, 1H, CHd), 6.48 (d, 1 H, J ) 3.8, SCCH), 4.33
(s, 5 H, C5H5)
50.6 (s)
50.6 (s)
7
9
7.94 (d, 1 H, J ) 4.5, SCCH), 7.50-7.10 (m, 37 H, Ph and SCCH 7 CHd), 7.21 (d, 1 H, SCCH), 4.36
48.6 (s)
50.6 (s)
(s, 5 H, C5H5)
8.15 (d, 2 H, J ) 8.9, C6H4), 7.50 (d, 2 H, C6H4), 7.46-7.08 (m, 30 H, Ph), 7.24 (d, 1 H, J ) 15.9, CHd),
6.93 (d, 1 H, J ) 3.8, SCCH), 6.67 (d, 1 H, CHd), 6.50 (d, 1 H, SCCH), 4.34 (s, 5 H, C5H5)
7.99 (d, 2 H, J ) 4.2, SCCH), 7.56-7.11 (m, 34 H, Ph), 7.32 (d, 2 H, SCCH), 4.42 (s, 5 H, C5H5)
8.18 (d, 2 H, J ) 8.8, C6H4), 7.53 (d, 2 H, C6H4), 7.47-7.08 (m, 30 H, Ph), 7.30 (d, 1 H, J ) 15.9, CHd),
7.00 (d, 1 H, J ) 3.8, SCCH), 6.97 (d, 1 H, J ) 15.7, CHd), 6.87 (d, 1 H, J ) 3.8, SCCH), 6.83 (d, 1 H,
J ) 15.9, CHd), 6.82 (d, 1 H, J ) 3.7, SCCH), 6.76 (d, 1 H, J ) 15.7, CHd), 6.49 (d, 1 H, J ) 3.7,
SCCH), 4.33 (s, 5 H, C5H5)
11
13
48.5 (s)
50.6 (s)
15
17
18
8.87 (s, 1 H, NdCH), 8.06 (d, 1 H, J ) 4.3, SCCH), 7.62 (d, 1 H, SCCH), 7.55-7.13 (m, 34 H, C6H4 and
55.7 (s)
Ph), 4.36 (s, 5 H, C5H5)
8.45 (d, 2 H, J ) 6.0, NCH), 7.53 (d, 1 H, J ) 15.9, CHd), 7.50-7.15 (m, 30 H, Ph), 7.41 (d, 2 H, NCHCH), 48.3 (s)
6.99 (d, 1 H, J ) 3.9, SCCH), 6.50 (d, 1 H, SCCH), 4.36 (s, 5 H, C5H5)
8.69 (d, 2 H, J ) 6.6, NCH), 8.07 (d, 2 H, NCHCH), 8.03 (d, 1 H, J ) 15.6, CHd), 7.44-7.16 (m, 31 H, Ph
and SCCH), 6.83 (d, 1 H, CHd), 6.60 (d, 1 H, J ) 3.6, SCCH), 4.42 (s, 5 H, C5H5), 4.40 (s, 3 H, CH3)
48.1 (s, 2 P, RuP),
-145 (heptet, 1 P,
J P-F ) 702, PF6)
20
21
8.56 (d, 2 H, J ) 6.3, NCH), 7.48-7.10 (m, 31 H, Ph and SCCH), 7.38 (d, 2 H, NCHCH), 6.51 (d, 1 H,
J ) 3.9, SCCH), 4.38 (s, 5 H, C5H5)
8.93 (d, 2 H, J ) 6.9, NCH), 7.69 (d, 2 H, NCHCH), 7.39-7.08 (m, 31 H, Ph and SCCH), 6.52 (d, 1 H,
J ) 4.2, SCCH), 4.51 (s, 3 H, CH3), 4.36 (s, 5 H, C5H5)
48.2 (s)
48.1 (s, 2 P, RuP),
-145 (heptet, 1 P,
J P-F ) 702, PF6)
48.2 (s)
23
25
26
27
7.92 (d, 1 H, J ) 4.3, SCCH), 7.49-7.12 (m, 32 H, Ph, CHd, and SCCH), 7.10 (d, 1 H, J ) 3.8, SCCH),
6.88 (d, 1 H, J ) 15.4, CHd), 6.53 (d, 1 H, J ) 3.8, SCCH), 4.38 (s, 5 H, C5H5)
7.99 (d, 1 H, J ) 4.4, SCCH), 7.50-7.16 (m, 32 H, Ph and SCCH), 6.54 (d, 1 H, J ) 3.9, SCCH), 4.39
(s, 5 H, C5H5)
7.99 (s, 1 H, CHdC(CN)2), 7.72 (d, 1 H, J ) 4.1, SCCH), 7.43-7.19 (m, 20 H, Ph), 6.69 (d, 1 H, SCCH),
4.49 (s, 5 H, C5H5)
48.2 (s)
48.0 (s)
8.26 (s, 1 H, CHdC(CN)2), 7.82 (d, 1 H, J ) 4.1, SCCH), 7.49-7.16 (m, 32 H, CHd, SCCH, and Ph),
7.34 (d, SCCH), 6.99 (d, 1 H, J ) 15.8, SCCH), 6.54 (d, 1 H, SCCH), 4.39 (s, 5 H, C5H5)
a
b
Compounds 2-13 and 21 were measured in CDCl3 solution; others were measured in acetone-d6. Reported in ppm relative to δ(Me4Si)
0 ppm. c Reported in ppm relative to δ(85% H3PO4) 0 ppm. Abbreviations: s ) singlet, d ) doublet, t ) triplet, m ) multiplet.
Ta ble 4. Electr on ic Absor p tion Sp ectr a l Da ta for
th e Com p ou n d s [λm a x n m (10-4E)]a
compd
CH2Cl2
THF
2
4
7
438 (2.86)
517 (4.11)
533 (2.42)
522 (3.37)
505 (1.98)
536 (4.47)
562 (1.27)
455 (3.56)
659 (5.09)
435 (2.88)
622 (2.63)
588 (2.79)
552 (3.10)
562 (4.76)
638 (4.91)
531 (3.39)
478 (2.91)
426 (2.61)
510 (3.88)
526 (2.41)
516 (3.20)
495 (2.01)
532 (4.18)
548 (0.74)
451 (3.79)
578 (>2.45)
431 (2.43)
550 (3.20)
577 (3.10)
542 (1.78)
551 (5.98)
622 (6.02)
524 (2.48)
476 (3.0)
9
11
13
15
17
18
20
21
23
25
26
27
A
F igu r e 1. Electronic spectra (2.5 × 10-5 M in CH2Cl2) of
compounds Ru(CtC-th-(E)-CHdCH-th-(E)-CHd(CN)2)-
(PPh3)2(η5-C5H5) (27) (s), HCtC-th-(E)-CHdCH-th-(E)-
CHd(CN)2 (- - -), Ru(CtC-th-(E)-CHdCH-th)(PPh3)2(η5-
C5H5): (s - - -), and RuCl(PPh3)2(η5-C5H5) (s -).
B
C
D
496 (1.4)
460 (4.0)
a
A ) Ru(CtC-th-NO2)(PPh3)2(η5-C5H5), B ) Ru(CtCC6H4CHd
moiety by an alkyne moiety diminishes the charge-
transfer absorption wavelength due to the mismatch of
a phenyl (or thienyl) p orbital and an alkynyl p orbital
in energy.30 Similar to literature reports,8b,31 replace-
CHC6H4NO2-4)(PPh3)2(η5-C5H5), C ) Ru(CtCC6H4NdCHC6H4NO2-
4)(PPh3)2(η5-C5H5), and
D
) Ru(CtCC6H4NO2-4)(PPh3)2(η5-
C5H5).
Other trends appear to be normal: (a) The λmax of the
charge-transfer band is found to increase in accordance
with the order of electron accepting ability, aldehyde <
nitro < dicyanovinyl < N-methylpyridinium.4a,28 (b) In
homologues which have thiophenes as the only aromatic
ring in the conjugation chain, elongation of the conjuga-
tion length results in a decrease in the energy of the
charge-transfer band.29 (c) Replacement of an alkene
(28) (a) Duan, X. M.; Konami, H.; Okada, S. O.; Kawa, H.; Matsuda,
H.; Nakanishi, H. J . Phys. Chem. 1996, 100, 17780. (b) Cheng, L. T.;
Tam, W.; Stevenson, S. H.; Meredith, G. R.; Rikken, G.; Marder, S. R.,
J . Phys. Chem. 1991, 95, 10631. (c) Hansch, C.; Leo, A.; Taft, R. W.
Chem. Rev. 1991, 91, 165. (d) Lupo, D.; Prass, W.; Scheunemann, U.;
Laschewsky, A.; Ringsdorf, H. J . Opt. Soc. Am. 1988, 5B, 300.
(29) (a) Tiemann, B. G.; Cheng, L. T.; Marder, S. R. J . Chem. Soc.,
Chem. Commun. 1993, 735. (b) Cheng, L. T.; Tam, W.; Marder, S. R.;
Steigman, A. E.; Rikken, G.; Spangler, C. W. J . Phys. Chem. 1991, 95,
10643.

2196 Organometallics, Vol. 17, No. 11, 1998
Wu et al.
Ta ble 5. Red ox P oten tia ls for Com p lexes in
CH2Cl2 a t 298 Ka
complex
Eox (∆Ep)/Ru(+2/+3)
Ered (∆Ep)b
2
4
+0.11 (92)
>-2.0
-0.08 (91), +0.54 (92)
+0.02 (80)
-1.96 (i)
7b
9
-1.39 (103)
-1.58 (85)
-1.35 (99)
-1.53 (114)
-1.29 (115)
>-2.0
-1.41 (137))
>-2.0
-1.44 (i)
-1.40 (91)
-1.34 (104)
-1.79 (i)
-1.67 (i)
-1.62 (98)
-1.56 (100)
-0.06 (94)
+0.07 (86)
11
13
15
17
18
20
21
23
25
26
27
A
-0.13 (92), +0.34 (78)
+0.002 (85)
-0.018 (i)
+0.018 (94)
-0.05 (74)
+0.15 (103)
-0.06 (95), +0.51 (91)
+0.03 (93), +0.64 (76)
+0.18 (88)
-0.06 (91), +0.52 (97)
+0.22 (96)
+0.01 (88)
F igu r e 2. Cyclic voltammogram of compound 13 in CH2-
Cl2 containing 0.1 M TBAP at 25 °C. Potentials are in V
versus Ag/AgNO3 (0.01 M in MeCN; scan rate 60 mV s-1).
B
a
Analyses were performed in 10-3 M deoxygenated CH2Cl2
solutions containing 0.1 M TBAP; scan rate is 60 mV. All potentials
in V vs ferrocene (0.00 V with peak separation of 105 mV in
were found to have a similar trend; however, the effect
is more prominent for complexes with a shorter conju-
gation chain. For instance, 2 (+0.11 V) vs 26 (+0.18
V) and Ru(CtC-th-NO2)(PPh3)2(η5-C5H5) (A) (+0.22 V),7
20 (-0.05 V) vs 21 (+0.15 V), and Ru(CtC-th-(E)-
CHdCH-th-Br)(PPh3)2(η5-C5H5) (-0.13 V)33 vs 4 (-0.08
V), 23 (-0.06 V), and 27 (-0.06 V). All complexes with
a nitro substituent have fully reversible reductive waves
within the -1.29 to -1.60 V range, which can be
assigned to reduction of the nitro substituent.8a The
corresponding terminal alkynes have such reversible
reduction waves appearing at somewhat lower reduction
potentials (-1.36 V of 22 vs -1.40 V of 23; -1.30 V of
24 vs -1.34 V of 25), whereas no such reduction waves
were observed in complexes without a nitro substituent,
such as Ru(CtC-th-(E)-CHdCH-th-Y)(PPh3)2(η5-C5H5)
(Y ) H, Br).36 The cyclic voltammogram of 13 is shown
in Figure 2. It is interesting to note that complexes with
two thienyl rings have a second reversible oxidation
wave, which is tentatively assigned as the oxidation
potential of Ru(III)/Ru(IV). This oxidation wave is not
observed in the corresponding terminal alkynes or (E)-
1-(5-ferrocenylethynyl-2-thienyl)-2-(5-nitro-2-thienyl)-
ethylene. We suspect that sulfur atoms in the thiophene
rings help to stabilize the ruthenium metal center after
removal of two electrons.
NLO Mea su r em en ts. Hyper-Rayleigh scattering
(HRS) experiments were performed on complexes 7, 9,
11, 13, 15, A, and H using an optical parametric
oscillating (OPO) laser source of wavelength 1560 nm
(see Experimental Section). The first hyperpolarizabili-
ties (â, 10-30 esu, (15%) obtained for 7, 9, 11, 13, 15,
A, and H are 294, 333, 210, 419, 308, 89, and 186,
respectively. The calculated static hyperpolarizabilities
(â0, 10-30 esu)37 are 138 (7), 163 (9), 109 (11), 195 (13),
and 129 (15), 42 (A), and 105 (H). The â0 value for
Ru((E)-4,4′-CtCC6H4CHdCHC6H4NO2)(PPh3)2(η5-C5-
H5) (H)8b in this study was lower than that measured
at 1064 nm, possibly due to the use of different solvents
and inadequacy of the undamped two-state model.
Thiophene rings were superior to benzene rings in
enhancing the molecular nonlinearity of organic chro-
mophores.38 In this study, we found that incorporation
b
CH2Cl2); scan range +0.4 to -2.0 V; i ) irreversible process. ∆Ep
) Epa - Epc, mV.
ment of an alkene entity in the conjugation chain of
ruthenium complexes by an imine entity resulted in a
decrease in the charge-transfer energy, i.e., 7 (533 nm)
vs 15 (562 nm). However, the significantly lower
oscillator strength of the charge-transfer transition in
15 (f ) 0.34 vs f ) 0.60 for 7) may be detrimental to the
quadratic optical nonlinearity.
Electr och em istr y. On the basis of theoretical cal-
culations,32 the HOMO of Ru(CtCR)(PH3)2(η5-C5H5) (R
) H, C6H5, C6H4-4-NO2) is a metal-centered orbital
mixed with the π and π* of the alkyne moiety. There-
fore, the oxidation potentials of ruthenium metals in
these complexes and analogues should change as the
σ-acetylide substituent varies. The oxidation potentials
of Ru(II)/Ru(III) (Table 5) for the complexes in this study
were found to be reversible except for 17. The oxidation
potential, Ru(II)/Ru(III), decreases as the conjugation
length increases, i.e., 2 (+0.11 V) vs 4 (-0.08 V), 9
(-0.06 V) vs 13 (-0.13 V), and 26 (+0.18 V) vs 27 (-0.06
V). This observation is analogous to what has been
reported for Cp2Fe[CtCC6H4]nSO2Me,33 bimetallic ses-
quifuvalene complexes,34 ruthenium σ-acetylide com-
plexes,7 and nickel σ-acetylide complexes.35 In the same
report32 the ionization potential of Ru(CtCC6H4-4-NO2)-
(PH3)2(η5-C5H5) was also calculated to be higher than
that of Ru(CtCC6H5)(PH3)2(η5-C5H5). Previously Hum-
phrey8a and we7 found that a better electron acceptor
raised the oxidation potential of the ruthenium atom
in ruthenium σ-acetylides. Complexes in this study
(30) Stiegman, A. E.; Graham, E.; Perry, K. J .; Khundkar, L. R.;
Cheng, L. T.; Perry, J . W. J . Am. Chem. Soc. 1991, 113, 7658.
(31) (a) Walree, C. A.; Franssen, O.; Marsman, A. W.; Flipse, M. C.;
J enneskens, L. W. J . Chem. Soc., Perkin Trans. 2 1997, 799. (b) Kuhn,
H., Robillard, J ., Eds. Nonlinear Optical Materials; CRC Press: Boca
Raton, FL, 1992; p 203. (c) Kolinsky, P. V. Opt. Eng. 1992, 31, 1676.
(32) McGrady, J . E.; Lovell, T.; Stranger, R.; Humphrey, M. G.
Organometallics 1997, 16, 4004.
(33) Hsung, R. P.; Chidsey, C. E. D.; Sita, L. R. Organometallics
1995, 14, 4808.
(34) Behrens, U.; Brussard, H.; Hagenau, U.; Heck, J .; Hendrickx,
E.; Ko¨rnich, J .; van der Linden, J . G. M.; Persoons, A.; Spek, A. L.;
Veldman, N.; Voss, B.; Wong, H. Chem. Eur. J . 1996, 2, 98.
(35) Whittall, I. R.; Cifuentes, M. P.; Humphrey, M. G.; Luther-
Davies, B.; Samoc, M.; Houbrechts, S.; Persoons, A.; Heath, G.;
Bogsa´nyi, D. Organometallics 1997, 16, 2631.
(36) Wu, I. Y.; Lin, J . T. Unpublished results.
(37) â0 was obtained using the two-level model, with â0 ) â[1 -
(2λmax/1560)2][1 - (λmax/1560)2].

Ruthenium σ-Acetylides
Organometallics, Vol. 17, No. 11, 1998 2197
F igu r e 4. ORTEP drawing of complex 26. Thermal
ellipsoids are drawn with 50% probability boundaries.
F igu r e 3. ORTEP drawing of complex 7. Thermal el-
lipsoids are drawn with 50% probability boundaries.
of thiophene rings in the conjugating bridges was also
beneficial for second-order optical nonlinearity of ru-
thenium σ-acetylides. For instance, replacement of
either of the benzene ring in H by thiophene ring results
in formation of 7 or 9, which has higher first hyperpo-
larizability. It was reported that thiophene leads to a
larger â values more effectively at the acceptor end;27
we did not find similar trend in this study. It is worth
noting that complex 11 has a â0 value comparable to
that of H despite the presence of a thienyl moiety in
the former. Apparently, mismatch of a phenyl p orbital
and an alkynyl p orbital in energy results in diminishing
the effect of thiophene ring for efficient charge trans-
fer.29b,30 Elongation of the conjugation chain is an
efficient route for enhancement of first hyperpolariz-
ability as long as saturation does not occur.38 Our
results in this study fulfill this trend, e.g., A < H or 7
and 9 < 13. Despite the contribution of multiple photon
absorption-induced fluorescence to the first hyperpo-
larizability of 15, which was not deducted, the â0 value
of 15 is still lower than that of 7. This observation may
be attributed to the significantly smaller oscillator
strength of the charge-transfer transition in 15. This
is in agreement with Humphrey’s report on H and Ru-
((E)-4,4′-CtCC6H4NdCHC6H4NO2)(PPh3)2(η5-C5H5) (â0
) 86 × 10-30 esu).8b In view of the highly intense
charge-transfer absorption with low transition energy
for some complexes such as 18, 21, and 27, one can be
optimistic that excellent optical nonlinearity is achiev-
able for ruthenium σ-acetylides containing the thienyl
moiety. Certainly, use of OPO laser source with even
longer wavelength than 1560 nm is necessary to probe
off-resonance nonlinearity of such complexes. A more
comprehensive investigation on optical nonlinearity of
complexes in this study and congener should be useful
in molecular engineering and will be the subject of
future publication. Syntheses of other organometallic
thienyl chromophores aiming at greater transparency
in the visible spectrum are also in progress.
F igu r e 5. Charge-separated canonical resonance form of
complex 26.
(7) Å; 26, 1.23(1) Å), and C7-C8 (7, 1.438(7) Å; 26, 1.42-
(1) Å) distances all fall within the range observed for
related ruthenium(II) σ-acetylide complexes.39 The
extent to which the acetylide participates in metal-to-
ligand back-bonding is in general difficult to be ad-
dressed from the structural data because of the relative
insensitivity of both metal-C and CtC bond lengths
to small changes in populations of the π or π* orbitals.39
Nevertheless, complex 26 was found to have a shorter
Ru-C6 distance and a longer C6tC7 distance than that
observed for Ru(CtCPh)(PPh3)2(η5-C5H5) (Ru-C, 2.017(5)
Å; CtC, 1.1214(7) Å),8a Ru(CtCC6H4NO2-4)(PPh3)2(η5-
C5H5) (Ru-C, 1.994(5) Å; CtC, 1.202(8) Å),8a and H
(Ru-C, 2.008(6) Å; CtC, 1.199(7) Å).8b It is noteworthy
that the latter three complexes possess shorter Ru-C
and longer CtC distances than other available ruthe-
nium σ-acetylides.8a We believe that there is an im-
portant contribution of the charge-separated vinylidene
form (Figure 5) to the ground state of 26, on the basis
of these observations together with the following struc-
tural data: (1) C7-C8 (1.42(1) Å) and C11-C12 (1.39-
(1) Å) distances are somewhat short compared to Csp-
Csp (1.43 Å) and Csp -Csp (1.48 Å),40 respectively. (2)
The olefinic C12-C13 (1.37(2) Å) distance is signifi-
2
2
2
40
2
2
cantly longer than that of a normal Csp dCsp (1.32 Å).
Other supporting evidence for charge-separated char-
acter of 26 include: (1) low CtC stretching frequency
(νCtC ) 2017 cm-1) among ruthenium σ-acetylides;39 (2)
very downfield shift of CR (δ ) 161.7 ppm) in 13C NMR
spectra; (3) upfield shift of dicyanomethine carbon
(C(CN)2) (δ ) 68.4 ppm) compared to that in thiophene-
2-ylmethylene malononitrile (δ ) 75.9 ppm).41
There is interesting dissimilarity in structure between
7 and 26, i.e., the relative orientation of the arylacetyl-
ide (or thienylacetylide) plane to the plane σv, defined
as the plane perpendicular to the plane P-Ru-P and
bisecting angle P-Ru-P. The phenylacetylide plane of
Molecu la r Str u ctu r es of Ru (CtCC6H5-(E)-CHd
CH-th -NO2)(P P h 3)2(η5-C5H5) (7) a n d Ru (CtC-th -
CHdC(CN)2)(P P h 3)2(η5-C5H5) (26). ORTEP drawings
of 7 and 26 are shown in Figures 3 and 4, respectively.
RusC6 (7, 2.013(5) Å; 26, 1.974(7) Å), C6tC7 (7, 1.190-
(39) Manna, J .; J ohn, K. D.; Hopkins, M. D. Adv. Organomet. Chem.
1995, 38, 79.
(40) March, J . Advanced Organic Chemistry, 4th ed., Wiley: New
York, 1992; p 21.
(38) Nalwa, H. S., Miyata, S., Eds. Nonlinear Optics of Organic
Molecules and Polymers; CRC Press: New York, 1997.
(41) Robinson, C. N.; Wiseman, J r.; Slater, C. D. Tetrahedron 1989,
45, 4103.

2198 Organometallics, Vol. 17, No. 11, 1998
Wu et al.
7 is nearly perpendicular to σv, whereas the thienyl-
acetylide plane of 26 is almost parallel to σv. The
relative orientation of arylacetylide to the metal coor-
dination sphere in 26 is the same as that observed for
Ru(CtCC6H4NO2-4)(L)2(η5-C5H5) (L ) PMe3, PPh3).8a
Although such a conformation is slightly beneficial for
first hyperpolarizability as pointed out by a theoretical
calculation on Ru(CtCC6H4NO2-4)(L)2(η5-C5H5),8a it is
uncertain whether the conformation retains in solution.
Other important structural features for 7 and 26
include the linearity of Ru-C6-C7-C8 (7, Ru-C6-C7
angle, 174.5(4)°, and C6-C7-C8 angle, 177.4(5)°; 26,
Ru-C6-C7 angle, 173.7(6)°, and C6-C7-C8 angle,
172.2(8)°) and the E conformation of the olefin (C14)Hd
(C15)H (C11-C14-C15 angle, 126.0(6)°; C14-C15-C16
angle, 128.6(6)°) in 7. The slight deviation of the
benzene ring and the thiophene ring in 7, or the
thiophene ring and the dicyanovinyl plane in 26, from
coplanarity (dihedral angle: 7, 10.8(3)°; 26, 15.5(3)°) is
possibly due to the crystal packing forces.
Con clu sion
We synthesized the first series of organometallic
second-order nonlinear optical chromophores which
incorporate a thiophene moiety in the conjugation chain.
These complexes were found to possess promising
quadratic hyperpolarizabilities determined from hyper-
Rayleigh scattering (HRS) experiments using an OPO
laser source.
Ack n ow led gm en t. We thank Academia Sinica and
the National Science Council (Grant NSC-87-2113-M-
001-010) for financial support.
Su p p or tin g In for m a tion Ava ila ble: Tables of atomic
coordinates (including hydrogen atoms), thermal parameters,
and bond distances and angles and stereoviews for complexes
7 and 26 (23 pages). Ordering information is given on any
current masthead page.
OM970947I