Near-infrared absorbing organoruthenium complexes: Crystal violet analogues

Article abstract of DOI:10.1021/om980853o

Replacement of "NR₂" substituents in crystal violet (or ethyl violet) by "CpRu(PPh₃)₂(C≡ C)" results in formation of stable derivatives of triaryl carbocations, {[CpRu(PPh₃)₂(C≡CC₆H _4<

Full text of DOI:10.1021/om980853o

320
Organometallics 1999, 18, 320-327
Nea r -In fr a r ed Absor bin g Or ga n or u th en iu m Com p lexes:
Cr ysta l Violet An a logu es
Iuan-Yuan Wu, J iann T. Lin,* and Yuh S. Wen
Institute of Chemistry, Academia Sinica, Taipei 115, Taiwan, Republic of China
Received October 14, 1998
Replacement of “NR2” substituents in crystal violet (or ethyl violet) by “CpRu(PPh3)2(Ct
C)” results in formation of stable derivatives of triaryl carbocations, {[CpRu(PPh3)2(CtCC6H4-
4)][Et2NC6H4-4]2}C+ (3+) and {[CpRu(PPh3)2(CtCC6H4-4)]2[Me2NC6H4-4]}C+ (5+), and {[CpRu-
(PPh3)2(CtCC6H4-4)]3}C+ (7+). They were isolated as BF4 salts. The stable carbocation
{[CpRu(PPh3)2(CtC-th((E)-CHdCH)-th)][Et2NC6H4-4]2}C+ (6+) (th ) 2,5-substituted thiophene),
has also been synthesized. These complexes exhibit intense electronic absorption in the near-
infrared region. Incorporation of thiophene rings was shown to enhance both λmax and f values.
Ta ble 1. Cr ysta l Da ta for Com p ou n d 1‚CH2Cl2
In tr od u ction
chem formula
fw
cryst size, mm
cryst syst
space group
a, Å
C64H54Cl2OP2Ru
1073.05
There currently is much interest in the development
of new infrared absorbing dyes because these materials
are useful in several fields: laser optical recording
systems, laser printing systems, laser thermal writing
displays, infrared photography, and mechanical or
biological applications.1 Research related to nonlinear
optical materials has shown that conjugating systems
with strong electron donors and acceptors, and/or with
extended conjugation, typically show more favorable
bathochromatic shifts in the charge-transfer absorp-
tion.2 Conceptually, these strategies can be applied to
the construction of near-infrared absorbing dyes. Indeed,
by choosing a powerful electron acceptor, thioflavylium,
and incorporating thiophene rings into the conjugation
chain, Chen and Marder were successful in synthesizing
several organic near-infrared absorbing dyes.3 Recently,
we,4 and Humphrey and co-workers5 have also demon-
strated that the “CpRu(PPh3)2” moiety in the ruthenium
σ-acetylides of the push-pull type is a very effective
electron donor which can considerably lower the energy
of the charge-transfer band in the visible region. Thus,
if a potent electron acceptor such as the cationic seven-
membered tropylium ring6 is linked to CpRu(PPh3)2, a
low-lying charge transfer from the electron donor to the
tropylium group is attainable if there exists an efficient
0.16 × 0.44 × 0.69
triclinic
P1h
11.301(7)
15.255(3)
15.982(5)
102.11(2)
96.94(4)
99.16(3)
2626(2)
b, Å
c, Å
R, deg
â, deg
γ, deg
V, Å3
Z
T, °C
2
+20
1108
0.7107
1.357
4.957
1.00-0.95
50
F(000)
λ(Mo KR), Å
F
calc, g cm-3
µ, cm-1
transm coeff
2θmax, deg
h, k, l range
-13 to 13, 0 to 18, -18 to 18
tot no. of reflns
no. of unique reflns
no. of obsd reflns (I > 2.0σ(I))
refined params
Ra
9740
9229
7696
631
0.038
0.046
2.04
b
Rw
GOF(F2)c
a
b
2
R ) Σ||Fo| - |Fc||/Σ|Fo|. Rw ) [Σw(|Fo| - |Fc|)2/Σw|Fo| ]1/2; w
) 1/[σ2(Fo) + kFo2] where k ) 0.0001. c GOF ) [Σw(Fo - Fc2)2/(n
- p)]1/2 where n ) no. of obsd reflns and p ) no. of variables.
2
* Corresponding author. Fax: Int. code +(2)27831237. E-mail:
jtlin@chem.sinica.edu.tw.
(1) (a) Matsuoka, M., Ed. Infrared Absorbing Dyes; Plenum Press:
New York, 1990. (b) Fablan, J .; Nakazumi, H.; Matsuoka, M. Chem.
Rev. 1992, 92, 1197.
(2) Nalwa, H. S., Miyata, S., Eds. Nonlinear Optics of Organic
Molecules and Polymers; CRC Press: New York, 1997.
(3) Chen, C. T.; Marder, S. R. Adv. Mater. 1995, 7, 1030.
(4) (a) Wu, I. Y.; Lin, J . T.; Sun, S. S.; Luo, J .; Li, C. S.; Wen, Y. S.;
Tsai, C. T.; Hsu, C. C.; Lin, J . L. Organometallics 1997, 16, 2038. (b)
Wu, I. Y.; Lin, J . T.; Luo, J .; Li, C. S.; Tsai, C. T.; Wen, Y. S.; Hsu, C.
C.; Yeh, F. F.; Liou, S. Organometallics 1998, 17, 2188.
(5) (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.
conjugation path between the two. Toward this end, we
set out to synthesize a new class of near-infrared
absorbers based on coupling the aforementioned ruthe-
nium σ-acetylides with a triphenylcarbenium moiety as
the acceptor. These NIR absorbers can be expected to
exhibit high ꢀ’s. In this report, we describe the synthesis
and characterization of several novel organoruthenium
NIR absorbers.
Exp er im en ta l Section
Gen er a l P r oced u r es. All reactions and manipulations
were carried out under N2 with the use of standard inert-
atmosphere and Schlenk techniques. Solvents were dried by
standard procedures. All column chromatography was per-
(6) (a) Behrens, U.; Brussaard, 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. (b) Tamm,
M.; J entzsch, T.; Werncke, W. Organometallics 1997, 16, 1418.
10.1021/om980853o CCC: $18.00 © 1999 American Chemical Society
Publication on Web 01/13/1999

Crystal Violet Analogues
Organometallics, Vol. 18, No. 3, 1999 321
formed with the use of silica gel (230-400 mesh ASTM, Merck)
as the stationary phase in a column 35 cm in length and 2.5
cm in diameter. Compounds Cp(PPh3)2Ru(CtCC6H4Br-p),7 Cp-
(PPh3)2Ru(CtC-th-(E)-CHdCH-th-Br) (th ) 2,5-substituted
thiophene),8 Cp(PPh3)2RuCl,9 PdCl2(PPh3)2,10 4,4′-diethynyl-
benzophenone,11 and (4-bromophenylethynyl)trimethylsilane12
were prepared by published procedures. Infrared measure-
ments were measured on a Perkin-Elmer 880 spectrometer.
The NMR spectra were recorded on Bruker AMX400 (1H, 13C,
31P) and AC300 (1H, 31P) spectrometers. Electronic absorption
spectra were obtained on a Perkin-Elmer Lambda 9 spectrom-
eter. Mass spectra (EI) were recorded on a VG70-250S mass
spectrometer. Elemental analyses were performed on a Perkin-
Elmer 2400 CHN analyzer.
NMR (120 MHz, C6D6, 25 °C, 85% H3PO4): δ ) 51.5. IR (KBr,
cm-1): 1089 (s, C-O), 2073 (vs, CtC).
[Cp (P P h 3)2Ru (CtCC6H4C(C6H4X-p)P h )][BF 4] (1b, X )
H; 2b, X ) OMe). Excess H+BF4 (54% Et2O solution) was
-
slowly added to a THF solution of 1 prechilled to 0 °C. The
resulting mixture was stirred for 5 min, and Et3N was added.
The complex 1b formed was characterized by electronic spectra
only. Attempted isolation of 1b resulted in recovery of 1.
Complex 2b was synthesized in a manner similar to that
employed for 1b, except that (4-methoxy)phenyllithium (pre-
pared in situ from 4-bromoanisole and t-BuLi) was utilized
instead of phenyllithium. Complex 2b was also characterized
by electronic spectra only. The two key precursors, (4-ethyn-
ylphenyl)(4′-methoxyphenyl)phenylmethanol (2a ) and Cp-
(PPh3)2Ru(CtCC6H4C(OMe)(C6H4OMe-p)Ph) (2), were isolated
and characterized. 2a : Anal. Calcd for C22H18O2: C 84.05, H
Cp (P P h 3)2Ru (CtCC6H4C(OMe)P h 2) (1). To a flask con-
taining a mixture of 4-bromobenzophenone (1.31 g, 5.0 mmol),
PdCl2(PPh3)2 (70 mg, 0.10 mmol), and CuI (10 mg, 0.050 mmol)
was added Et2NH (50 mL) and trimethylsilylacetylene (0.85
mL, 6.0 mmol) under a nitrogen atmosphere. The mixture was
stirred at room temperature for 5 h. The solvent was removed
under vacuum, and the residue was extracted with CH2Cl2/
H2O. The organic layer was collected, dried over MgSO4,
filtered through Al2O3, and pumped dry. The redidue was
recrystallized from CH2Cl2/hexane to afford pale brown crys-
talline 4-(trimethylsilylethynyl)benzophenone in 93% yield
1
5.77. Found: C 84.04, H 5.81. H NMR (300 MHz, CDCl3, 25
°C, TMS): δ ) 2.70 (br, 1 H, OH), 3.04 (s, 1 H, tCH), 3.78 (s,
3 H, OCH3), 6.81 (d, J ) 8.3 Hz, 2 H, C6H4-O), 7.13 (d, 2 H,
C6H4-O), 7.21-7.29 (m, 7 H, Ph and C6H4), 7.41 (d, J ) 8.4
Hz, 2 H, C6H4). 2: Anal. Calcd for C64H54O2P2Ru: C 75.50, H
5.35. Found: C 75.36, H 5.24. 1H NMR (300 MHz, C6D6, 25
°C, TMS): δ ) 3.13 (s, 3 H, OCH3), 3.32 (s, 3 H, OCH3), 4.49
(s, 5 H, Cp), 6.67 (d, J ) 8.8 Hz, 2 H, C6H4-O), 7.55 (d, 2 H,
C6H4-O), 7.61 (d, J ) 8.8 Hz, 2 H, C6H4), 7.64 (d, 2 H, C6H4),
6.90-7.23, 7.71-7.77 (m, 35 H, PPh3 and Ph). 31P NMR (120
MHz, C6D6, 25 °C, 85% H3PO4): δ ) 51.6. IR (KBr, cm-1):
1089, 1178 (s, C-O), 2073 (vs, CtC).
1
(1.30 g). H NMR (300 MHz, C6D6, 25 °C, TMS): δ ) 0.25 (s,
9 H, CH3), 7.44-7.74 (m, 9 H, Ph and C6H4). MS (EI): m/e
278 (M+), 263 (M+ - CH3). To a Et2O solution (100 mL) of
4-(trimethylsilylethynyl)benzophenone (1.39 g, 5.0 mmol) pre-
chilled to -30 °C was slowly added a solution of phenyllithium
(3.33 mL, 6.0 mmol, 1.8 M in cyclohexanes/ether). The solution
was slowly warmed to room temperature and stirred for 4 h.
One milliliter of H2O was added, and the solution was stirred
for 30 min. Additional H2O (>200 mL) was added, and the
organic layer was collected, dried over MgSO4, filtered through
Al2O3, and pumped dry. The residue was chromatographed
using CH2Cl2/hexane (2:1) as eluent to afford (4-ethynylphen-
yl)diphenylmethanol (1a ) as a pale yellow oil in 81% yield (1.24
g). This substance was spectroscopically identical with bona
fide 1a .13
[Cp (P P h 3)2R u (CtCC6H 4C(C6H 4NE t 2-p )2)][BF 4] (3). A
solution of t-BuLi (0.71 mL, 1.21 mmol, 1.7 M in pentane) was
added to a solution of Cp(PPh3)2Ru(CtCC6H4Br-p) in 25 mL
of Et2O prechilled to -78 °C. The solution was then stirred at
-30 °C for 15 min. After the solution was further warmed to
room temperature and stirred for 30 min, 4,4′-bis(diethylami-
no)benzophenone (0.35 g, 1.1 mmol) in 20 mL of THF was
slowly added and stirred for 16 h. After addition of 1 mL of
H2O, the solvent was removed in vacuo and the residue
extracted with CH2Cl2. The extract was filtered through Celite
and concentrated. Yellow powders formed upon addition of
hexane. The powders were collected and dried to provide Cp-
(PPh3)2Ru(CtCC6H4)C(OH)(C6H4NEt2-p)2 in 70% yield. 1H
NMR (300 MHz, CD3CN, 25 °C, TMS): δ ) 1.10 (t, J ) 7.0
Hz, 12 H, CH3), 3.31 (q, 8 H, CH2), 4.28 (s, 5 H, Cp), 6.62 (d,
J ) 8.9 Hz, 4 H, NC6H4), 6.97 (d, NC6H4), 7.10-7.46 (m, 34 H,
PPh3 and C6H4). 31P NMR (120 MHz, CD3CN, 25 °C, 85% H3-
PO4): δ ) 48.6. This crude compound was dissolved in 25 mL
of THF and cooled to 0 °C. A solution of HBF4 (0.30 mL, 54%
in Et2O) was added, and the resulting mixture was stirred for
5 min. Et3N (1 mL) was added, and the resulting green solution
was pumped dry. The residue was first washed with Et2O/
hexane (1:1) until the washing was clear, then washed rapidly
with H2O and dried. Recrystallization of the crude product
from CH2Cl2/hexane afforded green powdery 3 in 68% yield
(0.81 g). Anal. Calcd for C70H67BF4N2P2Ru: C 70.88, H 5.69,
N 2.36. Found: C 70.67, H 5.71, N 2.50. Mp ) 176 °C. 1H NMR
(300 MHz, CD3CN, 25 °C, TMS): δ ) 1.26 (t, J ) 7.1 Hz, 12
H, CH3), 3.60 (q, 8 H, CH2), 4.41 (s, 5 H, Cp), 6.94 (d, J ) 9.4
Hz, 4 H, NC6H4), 7.14-7.43 (m, 38 H, PPh3 and C6H4). 13C
NMR (100 MHz, CD3CN, 25 °C, TMS): δ ) 11.9 (CH3), 45.4
(CH2), 86.1 (Cp), 110.0 (Ru-CtCâ), 112.8 (NC6H4), 121.9
(C6H4), 126.6 (NC6H4), 127.5 (Cmeta of PPh3), 128.9 (Cpara of
PPh3), 130.4 (C6H4), 133.8 (Cortho of PPh3), 136.2 (C6H4), 137.5
(C6H4), 138.5 (t, J C-P ) 21.1 Hz, Cipso of PPh3), 140.4 (NC6H4),
146.0 (t, J C-P ) 24.6 Hz, Ru-CRtC), 154.6 (NC6H4), 176.7
(CPh3). 31P NMR (120 MHz, CD3CN, 25 °C, 85% H3PO4): δ )
48.5. IR (KBr, cm-1): 1073 (s, BF4), 2017 (s, CtC). Vis/NIR
(CH2Cl2, λmax (nm), ꢀ (104 M-1 cm-1): 609 nm, ꢀ ) 8.25, f )
0.62; 725 nm, ꢀ ) 3.79, f ) 0.49.
To a mixture of Cp(PPh3)2RuCl (0.36 g, 0.50 mmol) and 1a
(0.16 g, 0.56 mmol) was added 50 mL of MeOH. The resulting
mixture was refluxed for 3 h. The solution was cooled to 0 °C,
and Na (18 mg, 0.80 mmol) was added slowly. The solution
was filtered, and the yellow solid was washed with MeOH (3
× 10 mL) and hexane (3 × 5 mL). The crude product was
recrystallized from CH2Cl2/hexane to afford 1 as a yellow
powder in 77% yield (0.38 g). Anal. Calcd for C63H52OP2Ru: C
76.58, H 5.30. Found: C 76.31, H 5.21. 1H NMR (300 MHz,
C6D6, 25 °C, TMS): δ ) 3.05 (s, 3 H, CH3), 4.44 (s, 5 H, Cp),
7.51 (d, J ) 8.4 Hz, 2 H, C6H4), 7.56 (d, 2 H, C6H4), 6.88-7.10
and 7.62-7.74 (m, 40 H, PPh3 and Ph); 13C NMR (100 MHz,
CDCl3, 25 °C, TMS): δ ) 52.0 (OCH3), 85.2 (Cp), 87.1 (C(C6H4)-
Ph2), 114.3 (Ru-CtCâ), 116.9 (t, J C-P ) 24.0 Hz, Ru-CRtC),
126.6 (Ph), 127.2 (t, J ) 4.5 Hz, Cmeta of PPh3), 127.6 (Ph),
128.4 (Cpara of PPh3), 128.6 (Ph), 128.7 (C6H4), 129.3 (C6H4),
129.7 (C6H4), 133.8 (t, J C-P ) 5.0 Hz, Cortho of PPh3), 137.4
(C6H4), 138.9 (t, J C-P ) 20.7 Hz, Cipso of PPh3), 144.8 (Ph). 31P
(7) Bruce, M. I.; Koutsantonis, G. A.; Liddell, M. J .; Nicholson, B.
K. J . Organomet. Chem. 1987, 320, 217.
(8) Hsung, R. P.; Chidsey, C. E. D.; Sita, L. R. Organometallics 1995,
14, 4808.
(9) Bruce, M. I.; Hameister, C.; Swincer, A. G.; Wallis, R. C. Inorg.
Chem. 1990, 28, 270.
(10) Colquhoun, H. M., Holton, J ., Thompson, D. J ., Twigg, M. V.,
Eds. New Pathways for Organic Synthesis; Plenum Press: New York,
1984; Chapter 9.
(11) Royles, B. J . L.; Smith, D. M. J . Chem. Soc., Perkin Trans. 1
1994, 255.
(12) Steinmetz, M. G.; Yu, C.; Li, L. J . Am. Chem. Soc. 1994, 116,
932.
[Cp (P P h 3)2Ru (CtCC6H4)]2C(O) (4). To a flask containing
a mixture of 4,4′-dibromobenzophenone (5.0 g, 14.7 mmol),
PdCl2(PPh3)2 (0.42 mg, 0.60 mmol), and CuI (60 mg, 0.30
(13) Alexander, C.; Feasr, W. J . Synthesis 1992, 8, 735.

322 Organometallics, Vol. 18, No. 3, 1999
Wu et al.
mmol) was added THF (100 mL), iPr2NH (20 mL), and
trimethylsilylacetylene (4.6 mL, 32.5 mmol) under a nitrogen
atmosphere. The mixture was stirred at room temperature for
40 h. The solvent was removed under vacuum, and the residue
was extracted with CH2Cl2/H2O. The organic layer was col-
lected, dried over MgSO4, filtered through Al2O3, and pumped
dry. The residue was recrystallized from CH2Cl2/hexane at -30
°C to afford pale brown crystalline 4,4′-bis(trimethylsilylethyn-
yl)benzophenone (4a ) in 96% yield (5.29 g). 1H NMR (300 MHz,
C6D6, 25 °C, TMS): δ ) 0.25 (s, 18 H, CH3), 7.53 (d, J ) 8.6
Hz, 4 H, C6H4), 7.69 (d, 4 H, C6H4). To a mixture of 4a (1.0 g,
2.67 mmol) and KOH (0.30 g, 5.36 mmol) was added 50 mL of
MeOH, and the solution was stirred at room temperature for
3 h. The solution was then extracted with Et2O. The Et2O
solution was pumped dry, and the residue was chromato-
graphed using EtOAc/hexane (1:50 to 1:5) as eluent to afford
4,4′-diethynylbenzophenone (4b) in 68% yield (0.42 g). This
substance was spectroscopically identical with bona fide 4b.14
°C, TMS): δ ) 40.8 (CH3), 86.6 (Cp), 113.3 (NCCH), 127.5
(Cmeta of PPh3), 128.2 (NCCHCHC), 128.3 (Ru-CtCâ), 128.9
(Cpara of PPh3), 131.2 (CtCCCH), 133.6 (Cortho of PPh3), 134.1
(CtCC), 136.8 (CtCCCHCH), 138.0 (t, J C-P ) 21.4 Hz, Cipso
of PPh3), 139.3 (CtCCCHCHC), 140.6 (NCCHCH), 156.5
(CH3NC), 158.7 (t, J C-P ) 24.6 Hz, Ru-CRtC), 176.7 (C(C6H4)3).
31P NMR (120 MHz, CD3CN, 25 °C, 85% H3PO4): δ ) 48.4. IR
(KBr, cm-1): 1085 (m, BF4), 1995 (vs, CtC), 2035 (sh, CtC).
Vis/NIR (CH2Cl2, λmax (nm), ꢀ (104 M-1 cm-1): 740 nm, ꢀ )
6.78, f ) 1.08; 855 nm, ꢀ ) 7.74, f ) 0.84.
[Cp (P P h 3)2R u (CtC-t h -(E)-CH dCH -t h -C(C6H 4NE t 2)2]-
[BF 4] (6). Complex 6 was synthesized by the same procedure
as employed for 3 except that Cp(PPh3)2Ru(CtC-th-(E)-CHd
CH-th-Br) (th ) 2,5-substituted thiophene)8 was used instead
of Cp(PPh3)2Ru(CtCC6H4Br-p). Dark blue powdery 6 was
isolated in 70% yield. Anal. Calcd for C74H69BF4N2P2S2Ru: C
68.35, H 5.35, N 2.15. Found: C 68.20, H 5.22, N 2.07. Tdecomp
1
) 156 °C. H NMR (300 MHz, CD3CN, 25 °C, TMS): δ ) 1.25
(t, 3J ) 6.8 Hz, 12 H, CH3), 3.59 (q, 8 H, CH2), 4.36 (s, 5 H,
Cp), 6.54 (d, J ) 3.8 Hz, 1 H, SCCH), 6.94 (d, J ) 9.3 Hz, 4 H,
C6H4), 6.97 (d, 1 H, J ) 16.5 Hz, 1 H, dCH), 7.09-7.50 (m, 38
H, PPh3, dCH, SCCH, and C6H4). 13C NMR (100 MHz, CD3-
CN, 25 °C, TMS): δ ) 12.0 (CH3), 45.3 (CH2), 85.8 (Cp), 110.0
(Ru-CtCâ), 110.6 (NC6H4), 124.8 (SCd), 125.5 (NC6H4), 127.3
(C6H4), 127.4 (C6H4), 127.5 (t, J C-P ) 4.6 Hz, Cmeta of PPh3),
128.3 (C6H4), 128.8 (C6H4), 128.9 (Cpara of PPh3), 133.5 (t, J C-P
) 4.9 Hz, Cortho of PPh3), 133.6 (NC6H4), 134.0 (SCd), 138.6 (t,
J C-P ) 21.0 Hz, Cipso of PPh3), 139.3 (t, J C-P ) 24.0 Hz, Ru-
CRtC), 146.8 (SCd or C(C6H4)2th), 153.1 (C(C6H4)2th or
SCd), 154.1 (NC6H4). 31P NMR (120 MHz, CD3CN, 25 °C, 85%
H3PO4): δ ) 48.0. IR (KBr, cm-1): 1085 (m, BF4), 2009 (vs,
CtC). Vis/NIR (CH2Cl2, λmax (nm), ꢀ (104 M-1 cm-1): 897 nm,
ꢀ ) 6.74, f ) 0.88.
To a mixture of Cp(PPh3)2RuCl (1.45 g, 2.0 mmol), 4b (0.23
g, 1.0 mmol), and NH4+PF6- (0.33 g, 2.1 mmol) were added 50
mL of MeOH and 40 mL of CH2Cl2. The resulting mixture was
refluxed for 3 h. The solution was cooled to room temperature,
and 3 mL of Et3N was added. After the solvent was removed,
the residue was chromatographed using EtOAc/hexane (1:5)
as eluent to afford 4 as a yellow powder was in 65% yield (1.05
g). Anal. Calcd for C99H78OP4Ru2: C 73.87, H 4.88. Found: C
1
73.50, H 4.49. H NMR (300 MHz, CD3CN, 25 °C, TMS): δ )
4.39 (s, 10 H, Cp), 7.16-7.54 (m, 60 H, PPh3), 7.21 (d, J ) 8.3
Hz, 4 H, C6H4), 7.61 (d, 4 H, C6H4). 13C NMR (100 MHz, CDCl3,
25 °C, TMS): δ ) 85.4 (Cp), 116.0 (Ru-CtCâ), 127.2 (t, J C-P
) 24.6 Hz, Ru-CRtC), 127.3 (Cmeta of PPh3), 128.5 (Cpara of
PPh3), 129.9 (C6H4), 130.1 (C6H4), 132.6 (C6H4), 133.8 (t, J C-P
) 5.1 Hz, Cortho of PPh3), 134.5 (C6H4), 138.7 (t, J C-P ) 20.9
Hz, Cipso of PPh3), 195.7 (CO). 31P NMR (120 MHz, CD3CN, 25
°C, 85% H3PO4): δ ) 48.7. IR (KBr, cm-1): 1640 (m, CO), 2062
(vs, CtC).
[{Cp (P P h 3)2Ru (CtCC6H4)}3C][BF 4] (7). A solution of
n-BuLi (2.1 mL, 3.36 mmol, 1.6 M in hexane) was added to a
solution of (4-bromophenylethynyl)trimethylsilane (0.69 mg,
2.74 mmol) in 50 mL of Et2O prechilled to -78 °C. The solution
was then stirred at -30 °C for 15 min. The solution was
warmed to room temperature, stirred for 1 h, and cooled to
-30 °C. A THF solution (20 mL) of 4a (0.83 g, 2.19 mmol)
prechilled to -30 °C was added slowly, and the resulting
mixture was stirred for 15 min. The solution was warmed to
0 °C and stirred for 2 h. After addition of 1 mL of H2O the
solution was pumped dry. The residue was chromatographed
using CH2Cl2/hexane (1:5 to 2:1) as eluent to afford tris(4-
(trimethylsilylethynyl)phenyl)methanol (7a ) as a colorless
[{Cp (P P h 3)2Ru (CtCC6H4)}2C(C6H4NMe2)][BF 4] (5). A
solution of t-BuLi (0.78 mL, 1.33 mmol, 1.7 M in pentane) was
added to a solution of 4-bromo-N,N-dimethylaniline (0.12 g,
0.60 mmol) in 20 mL of THF prechilled to -78 °C. The solution
was then stirred at -30 °C for 15 min. The solution was
further warmed to room temperature and stirred for 30 min.
This solution was slowly added to a solution of [Cp(PPh3)2Ru-
(CtCC6H4)]2CO (4) (0.80 g, 0.50 mmol) in 20 mL of THF, and
the mixture was stirred at room temperature for 16 h. After
addition of 1 mL of H2O, the solvent was removed in vacuo
and the residue extracted with CH2Cl2. The extract was filtered
through Celite and concentrated. A yellow powder formed upon
addition of hexane. The powder was collected and dried to
provide [Cp(PPh3)2Ru(CtCC6H4)]2C(OH)(C6H4NMe2) in 65%
1
powder in 77% yield (0.92 g). H NMR (300 MHz, CDCl3, 25
°C, TMS): δ ) 0.22 (s, 27 H, CH3), 2.72 (s, 1 H, OH), 7.13 (d,
J ) 8.4 Hz, 6 H, C6H4), 7.38 (d, 6 H, C6H4). To a mixture of 7a
(0.92 g, 1.68 mmol) and KOH (0.28 g, 5.0 mmol) was added 50
mL of MeOH, and the solution was stirred at room tempera-
ture for 3 h. The solution was then extracted with Et2O. The
Et2O solution was pumped dry, and the residue was chro-
matographed using EtOAc/hexane (1:50 to 1:5) as eluent to
afford tris(4-ethynylphenyl)methanol (7b) as a colorless pow-
der in 84% yield (0.47 g). Anal. Calcd for C34H40Si3O: C 74.39,
1
yield. H NMR (300 MHz, CDCl3, 25 °C, TMS): δ ) 2.63 (s, 6
H, CH3), 4.56 (s, 10 H, Cp), 6.54 (d, J ) 8.9 Hz, 2 H, NC6H4),
7.54 (d, 2 H, NC6H4), 7.61 (d, J ) 8.5 Hz, 4 H, C6H4), 7.68 (d,
4 H, C6H4), 7.02-7.83 (m, 60 H, PPh3). 31P NMR (120 MHz,
CDCl3, 25 °C, 85% H3PO4): δ ) 50.3. This crude compound
was dissolved in 25 mL of THF and cooled to 0 °C. A solution
of HBF4 (0.20 mL, 54% in Et2O) was added, and the resulting
mixture was stirred for 5 min. Et3N (1 mL) was added, and
the resulting green solution was pumped dry. The residue was
first washed with Et2O/hexane (1:1) until the washing was
clear, then washed rapidly with H2O, and dried. Recrystalli-
zation of the crude product from CH2Cl2/hexane afforded green
powdery 5 in 74% yield (0.67 g). Anal. Calcd for C107H88BF4-
NP4Ru2: C 71.37, H 4.93, N 0.78. Found: C 70.98, H 4.82, N
1
H 7.34. Found: C 74.03, H 7.28. H NMR (300 MHz, CDCl3,
25 °C, TMS): δ ) 2.73 (s, 1 H, OH), 3.06 (s, 3 H, tCH), 7.19
(d, J ) 8.2 Hz, 6 H, C6H4), 7.43 (d, 6 H, C6H4). IR (KBr, cm-1):
1018 (m, C-O), 2107 (w, CtC); 3554(m, O-H).
To a mixture of Cp(PPh3)2RuCl (1.20 g, 1.65 mmol), 7b (166
mg, 0.50 mmol), and Tl+PF6- (0.55 g, 1.58 mmol) were added
30 mL of MeOH and 20 mL of THF. The resulting mixture
was heated at 80 °C for 3.5 h. The solution was cooled to room
temperature and a solution NaOMe, prepared in situ from Na
(60 mg) and MeOH (10 mL), was added. After filtration the
yellow solid was chromatographed using EtOAc/hexane (2:3
to 1:2) as eluent. The yellow powdery [Cp(PPh3)2Ru(Ct
CC6H4)]3C(OMe) (7c) was isolated in 30% yield (0.36 g). Anal.
Calcd for C148H118OP6Ru3: C 74.02, H 4.95. Found: C 73.70,
1
0.59. Mp ) 185 °C. H NMR (300 MHz, CD3CN, 25 °C, TMS):
δ ) 3.29 (s, 6 H, CH3), 4.44 (s, 10 H, Cp), 6.99 (d, J ) 9.3 Hz,
2 H, NC6H4), 7.12-7.44 (m, 68 H, PPh3 and C6H4), 7.51 (d, 2
H, NC6H4). 13C NMR (100 MHz, CD3CN, HMBC & HMQC, 25
(14) Royles, B. J . L.; Smith, D. M. J . Chem. Soc., Perkin Trans. 1
1984, 4, 355.
1
H 5.01. H NMR (300 MHz, CDCl3, 25 °C, TMS): δ ) 3.08 (s,

Crystal Violet Analogues
Organometallics, Vol. 18, No. 3, 1999 323
Sch em e 1
Ta ble 2. Selected Bon d Dista n ces (Å) a n d An gles
Ch a r t 1
(d eg) for Com p lex 1‚CH2Cl2
Distances
Ru-C1
Ru-C2
Ru-C3
Ru-C4
Ru-C5
Ru-C6
Ru-P1
Ru-P2
C6-C7
C7-C8
C8-C9
2.241(3)
2.235(4)
2.223(3)
2.258(3)
2.242(3)
2.022(3)
2.287(1)
2.293(2)
1.210(4)
1.439(4)
1.404(5)
C9-C10
C10-C11
C11-C12
C12-C13
C13-C8
C11-C14
C14-C21
C14-C31
C14-O
1.384(5)
1.386(4)
1.391(4)
1.380(5)
1.390(5)
1.543(4)
1.530(5)
1.533(5)
1.446(4)
1.416(5)
C15-O
Angles
102.14(5)
86.89(9)
87.3(1)
178.0(3)
175.0(4)
113.6(3)
P1-Ru-P2
P1-Ru-C6
P2-Ru-C6
Ru-C6-C7
C6-C7-C8
C11-C14-C21
C11-C14-C31
C21-C14-C31
C11-C14-O
C21-C14-O
C31-C14-O
105.7(3)
112.5(3)
111.0(2)
108.8(3)
104.9(2)
3 H, OCH3), 4.29 (s, 15 H, Cp), 7.04-7.09, 7.15-7.21, 7.45-
7.49 (m, 102 H, PPh3 and C6H4). 13C NMR (100 MHz, CDCl3,
25 °C, TMS): δ ) 52.0 (OCH3), 85.2 (Cp), 87.2 (C(C6H4)3), 114.5
(Ru-CtCâ), 115.0 (t, J C-P ) 24.8 Hz, Ru-CRtC), 127.2 (t, J C-P
) 4.4 Hz, Cmeta of PPh3), 128.6 (Cpara of PPh3), 128.6 (C6H4),
129.6 (C6H4), 129.6 (C6H4), 133.9 (t, J C-P ) 4.9 Hz, Cortho of
PPh3), 139.0 (t, J C-P ) 20.8 Hz, Cipso of PPh3), 139.2 (C6H4);
31P NMR (120 MHz, CDCl3, 25 °C, 85% H3PO4): δ ) 51.0. IR
(KBr, cm-1): 1089 (m, s, C-O), 2072 (vs, CtC). A solution of
2 mL, and 25 mL of Et2O was added. The solution was filtered,
and the solid was washed with H2O and Et2O. The crude
product was recrystallized from CH2Cl2/hexane to afford green
powdery 7‚2CH2Cl2 in 80% yield (82 mg). Anal. Calcd for
H+BF4 (0.2 mL, 54% Et2O solution) was slowly added to a
-
THF (5 mL) solution of 7c (80 mg, 0.033 mmol) prechilled to
0 °C. The resulting mixture was stirred for 5 min, and 0.5 mL
of Et3N was added. The volume of the solution was reduced to
C
150H121BCl4F4P6Ru3: C 68.21, H 4.62. Found: C 68.17, H 4.83.
Tdecomp ) 197 °C. 1H NMR (300 MHz, CDCl3, 25 °C, TMS): 4.47

324 Organometallics, Vol. 18, No. 3, 1999
Wu et al.
Sch em e 2
(s, 15 H, Cp), 5.27 (s, 4 H, CH2Cl2), 7.10-7.16, 7.25-7.28,
7.36-7.44 (m, 102 H, Ph and C6H4). 13C NMR (100 MHz,
CDCl3, 25 °C, TMS): δ ) 87.0 (Cp), 127.6 (J C-P ) 4.7 Hz, Cmeta
of PPh3), 128.4 (Ru-CtCâ), 128.9 (Cpara of PPh3), 131.6 (C6H4),
133.7 (t, J C-P ) 5.1 Hz, Cortho of PPh3), 135.4 (C6H4), 136.9
(C6H4), 137.6 (t, J C-P ) 21.6 Hz, Cipso of PPh3), 139.9 (C6H4),
166.2 (t, J C-P ) 23.5 Hz, Ru-CRtC), 174.2 (C(C6H4)3). 31P NMR
(120 MHz, CDCl3, 25 °C, 85% H3PO4): δ ) 50.8. IR (KBr,
cm-1): 1090 (m, BF4), 1986 (vs, CtC). Vis/NIR (CH2Cl2, λmax
(nm), ꢀ (104 M-1 cm-1): 974 nm, ꢀ ) 11.5, f ) 1.34.
2θ range. Other relevant experimental details are listed in
Table 1. The structure was solved by direct methods using
NRCVAX15 and refined by full-matrix least-squares (based on
F2) using SHELXL-93. All non-hydrogen atoms were refined
with anisotropic displacement parameters, and all hydrogen
atoms were were placed in idealized positions with dC-H ) 0.95
Å. The selected interatomic distances and bond angles are
given in Table 2. All other crystal data for 2‚CH2Cl2 are given
in the Supporting Information.
Cr ysta llogr a p h ic Stu d ies. Crystals of 1‚CH2Cl2 were
grown by slow diffusion of hexane into a concentrated solution
of 1 in CH2Cl2. Crystals were mounted on a glass fiber covered
with epoxy. Data were collected at 294 K on an Enraf-Nonius
CAD4 diffractometer by using graphite-monochromated Mo KR
radiation (λ ) 0.710 73 Å) with the θ-2θ scan mode. Unit cells
were determined by centering 25 reflections in the suitable
Resu lts a n d Discu ssion
Syn th eses of Ru th en iu m Tr ityl Com p lexes. Ru-
thenium trityl complexes synthesized in this study are
(15) Gabe, E. J .; LePage, Y.; Charland, J . P.; Lee, F. L.; White, P.
S. J . Appl. Crystallogr. 1989, 22, 384.

Crystal Violet Analogues
Organometallics, Vol. 18, No. 3, 1999 325
depicted in Chart 1. Complexes 3, 5, and 6 were
synthesized via three major sequential steps (Scheme
1): (1) the conversion of aryl bromides to aryl anions;16
(2) the reaction of appropriate diaryl ketones with
aryllithium compounds to form triaryl carbinols;17 (3)
18
the protonation of the carbinols by HBF4 followed by
treatment with NEt3. The new diaryl ketone, 4, was
prepared from the reaction of CpRu(PPh3)2Cl with 4,4′-
diethynylbenzophenone according to the well-known
procedure19 (eq 1). The triaryl carbinols formed in the
F igu r e 1. Electronic spectra (1.25 × 10-5 M in CH2Cl2) of
complexes 3 (dashed) and 6 (solid).
Ch a r t 2
second step were characterized spectroscopically (Ex-
perimental Section), and the crude compounds were
used for further reactions. Upon acid treatment of the
carbinols in the step 3, the formation of triaryl carboca-
tions is believed to occur with concurrent protonation
of the â-carbon atoms of ruthenium σ-acetylides and the
dialkylamino substituents on phenyl rings. Et3N was
found to be effective to deprotonate these intermediates
without detriment to the carbocations (vide infra). We
were not able to synthesize 7 from the reaction of Cp-
(PPh3)2Ru(CtCC6H4Li-p) with 4, a pathway similar to
that described in Scheme 1, possibly due to the steric
crowding of the two reactants. Complexes 7, 1b, and 2b
were prepared according to the sequential steps in
Scheme 2. Triphenyl carbinols were synthesized before
the incorporation of the ruthenium σ-acetylide moiety,
and analytically pure ruthenium σ-acetylides in which
the triphenyl carbinol moiety is converted to methyl-
triphenylmethylether could be isolated (step 1). The
protonation of methyltriphenylmethylether with HBF4
followed by treatment with NEt3 then affords the
desired triaryl carbocations (step 2).20 The kinetic
stability of these new trityl complexes varies with the
nature of the acceptor. For instance, the complexes 1b
and 2b readily react with NaOMe to reform the starting
materials and can only be characterized by electronic
absorption spectra (1b, λmax ) 766 nm; 2b, λmax ) 819
nm in CH2Cl2), We were able to trap 1b by MeOH to
form 1, the structure of which was confirmed by single-
crystal X-ray analysis (vide infra).
the introduction of dialkylamino substituents on the
phenyl rings of 1b should enhance the stability of the
carbocation. Indeed, we have prepared and character-
ized two unsymmetrical crystal violet analogues, 3 and
5 (Chart 1). We have also synthesized complex 6, which
incorporates a thiophene ring in the conjugation chain.
The resonance interaction of the dialkylamino moiety
with the carbocation certainly (vide infra) enhances the
stability of 3, 5, and 6 ver su s 1b and 2b. Complex 7,
in which all three “NMe2” substituents in the crystal
violet are replaced by “Cp(PPh3)2Ru(CtC)”, has also
been synthesized. The stability of 7 may be attributed
to the efficient dissipation of the positive charge through-
out the multimetal centers, similar to 1,1,5,5,-tetrafer-
rocenylpenta-2,3,4-trienylium22 and [Cp*(dppe)RudCd
CdCHCtCRu(dppe)Cp*]+.23 Complexes 3 and 5-7 are
stable in common solvents, including MeOH and H2O,
under ambient conditions in air.
Sp ectr oscop ic Stu d ies. The spectroscopic properties
of the new organoruthenium trityl complexes are con-
sistent with their formulations. The prominent feature
of the carbocations is the rather downfield shift (153.1-
176.7 ppm) in the 13NMR spectra for the carbon atom
bearing the positive charge.18,24 The presence of the
ruthenium σ-acetylide moiety in the complexes is sup-
ported by a characteristic downfield shift of δ(CR)
(139.3-166.2) in the 13NMR spectra and the existence
of a ν(CtC) stretching (1986-2035 cm-1) in the infrared
spectra.19 In these complexes, the importance of the
canonical resonance form A (Chart 2) as a contributor
to the ground electronic state is supported by the NMR
spectroscopic data: (1) the methylene protons of NEt2
in 3 (δ ) 3.60 ppm) and 6 (δ ) 3.59 ppm) or the methyl
It is well-known that dyes of the crystal violet21 type
are fairly stable under ambient conditions. Therefore,
(16) (a) Rogers, H. R.; Houk, J . J . Am. Chme. Soc. 1982, 104, 522.
(b) Rajca, A.; Wongsriratanakul, J .; Rajca, S. J . Am. Chem. Soc. 1997,
119, 11674.
(17) (a) Erickson, J . L. E.; Kitchens, G. C. J . Am. Chem. Soc. 1946,
68, 492. (b) Ishii, A.; Horikawa, Y.; Takaki, I.; Shibata, J .; Nakayama,
J .; Hoshino, M. Tetrahedron Lett. 1991, 32, 4313.
(18) Abarca, B.; Asensio, G.; Ballesteros, R.; Varea, T. J . Org. Chem.
1991, 56, 3224.
(19) (a) Bruce, M. I.; Swincer, A. G. Adv. Organomet. Chem. 1983,
22, 59. (b) Bruce, M. I. Chem. Rev. 1991, 91, 270. (c) Manna, J .; J ohn,
K. D.; Hopkins, M. D. Adv. Organomet. Chem. 1995, 38, 79.
(20) Hellwinkel, D.; Stahl, H.; Gaa, H. G. Angew. Chem., Int. Ed.
Engl. 1987, 26, 794.
(22) Bildstein, B.; Schweiger, M.; Kopacka, H.; Ongania, K.-H.;
Wurst, K. Organometallics 1998, 17, 2414.
(23) J ia, G.; Xia, H. P.; Wu, W. F.; Ng, W. S. Organometallics 1996,
15, 3634.
(24) Arnett, E. M.; Flowers, R. A., II; Ludwig, R. T.; Meekhof, A. E.;
Walek, S. A. J . Phys. Org. Chem. 1997, 10, 499.
(21) (a) Sinha, S. K.; Katiyar, S. S. J . Phys. Chem. 1970, 74, 1382.
(b) Beach, S. F.; Hepworth, J . D.; J ones, P.; Mason, D.; Sawyer, J .;
Hallas, G.; Mitchell, M. M. J . Chem. Soc., Perkin Trans. 2 1989, 1087.
(c) Yariv, S.; Ghosh, D. K.; Hepler, L. G. J . Chem. Soc., Faraday Trans.
1991, 87, 1201.

326 Organometallics, Vol. 18, No. 3, 1999
Ta ble 3. Absor p tion Con sta n ts for Or ga n om eta llic a n d Or ga n ic NIR Absor ber
Wu et al.
compound
λmax (nm)
ꢀ (10-4 M-1 cm-1
)
f
5
6
7
855
7.74
6.74
11.5
1.3
0.84
0.88
1.34
0.25
897
974
852
1302
851
816
845
(E)-1-ferrocenyl-2-(4-thioflavyliumyl)ethylene perchloratea
[{Fe(η5-C5Me5)(η2-dppe)}2(µ-CtC-CtC)][PF6]b
1.2
c
[Cp(PPh3)2Os(µ-CN)Ru(NH3)5][CF3SO3]3
0.34
0.55
1.12
0.11
0.18
[CpFe(η5-C5H4)CHdCH(η7-C7H6)][PF6]d
[CpFe(η5-C5H4)Z(η7-C7H6)][PF6],d
Z ) thiophene-1,5-diyl
Fc(CHdCH)nFc (Fc )ferrocenyl, n ) 1-6)e
[{(η5-C5H5)2Fe2(CO)2(µ-CO)}2(µ-C-(CHdCH)3-CHdC)][BF4]f
1,1,5,5-tetraferrocenylpenta-2,3,4-trien-1-ylium tetrafluoroborateg
D-(CHdCH)3-A (D ) julolidinyl, A ) thioflavylium)h
[4,4′-bis(N,N-di-p-methoxyphenylamino)tolane]+i
1647-2036
730
917
882
1751
0.13-0.21
24.3
1.78
9.3
2.23
1.37
0.36
1.55
0.35
g
h
i
a-f References 27a-f. Reference 22. Reference 3. Reference 27g.
protons (δ ) 3.29 ppm) of NMe2 in 5 exhibit chemical
shifts at much lower field than those of their alcohol
precursors in which no resonance from the amino group
is possible (NEt2, 3.31 ppm; NMe2, 2.90 ppm in CD3-
CN); (2) the chemical shifts of the methylene protons of
NEt2 in 3 and 6 are similar to those of ethyl violet (δ )
3.56 ppm in CD3CN) and at lower field than those of
the methylene protons of N,N-diethylaniline (δ ) 3.35
ppm in CD3CN). However, it is apparent that canonical
resonance form B cannot be neglected in light of the
following observations: (1) the chemical shifts of the
R-carbon atoms in the “ruthenium σ-acetylide” moiety
appear at significantly lower field than those of typical
ruthenium σ-acetylides;4a,5 (2) the CtC stretching fre-
quencies of 3 and 5-7 occur in the low energy region
among ruthenium σ-acetylides.19
Unsymmetrical dyes of crystal violet (or malachite
green) analogues normally exhibit two types of absorp-
tion bands, the x and y bands.25 These two bands are
observed for 3, 5, and 6. Contribution of the ruthenium
moiety to the low-lying electronic absorption is most
evident from the considerable bathochromic shift of the
electronic absorption spectra of 1b (λmax ) 766 nm in
CH2Cl2), 3 (λmax ) 725 nm in CH2Cl2), 5 (λmax ) 855 nm
in CH2Cl2), and 6 (λmax ) 897 nm in CH2Cl2) compared
with those of ethyl violet (λmax ) 587 nm in CH2Cl2) and
several azulene analogues (λmax < 630 nm in CH3CN)
of the triphenyl methyl cation.26 Incorporation of the
thiophene ring is expected to lower the energy of the
charge-transfer transitions.4b Indeed, complex 6 exhibits
a substantially bathochromic shift for λmax compared to
3 (Figure 1). The complex 7, which is symmetrical in
structure, exhibits the longest λmax (974 nm) and the
highest f (1.34) among the complexes in this study.
Moreover, 7, as well as 5 and 6, exhibits the highest
absorption intensity among organometallic complexes
which absorb at λmax ) 800 nm (Table 3).
F igu r e 2. ORTEP drawing of complex 1. Thermal el-
lipsoids are drawn with 50% probability boundaries.
Molecu la r Str u ctu r es of Cp (P P h 3)2Ru (CtCC6-
H4C(OMe)P h 2) (1‚CH2Cl2). An ORTEP drawing of 1
is shown in Figure 2. Humphrey suggested that the
presence of a strong acceptor acetylide ligand might
lengthen the Ru-P distance.5b Ru-P distances (2.287(1),
2.293(2) Å) for 1 are substantially longer than those in
Ru(CtCPh)(PPh3)2(η5-C5H5) (2.228(3), 2.229(3) Å)28 de-
spite the absence of a strong acceptor. The Ru-C6
distance (2.022(3) Å) is somewhat long among related
ruthenium(II) σ-acetylide complexes,19c although no
apparent steric interaction is found to exist inter- or
intramolecularly. C6-C7 (1.210(4) Å) and C7-C8
(1.439(4) Å) distances as well as Ru-C6-C7 (178.0(3)°)
and C6-C7-C8 (175.0(4)°) angles all fall within the
range observed for similar complexes.19c
Lewis reported that increasing the number of NR2
25a
substituents decreased the λmax
.
Our results are in
(27) (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) Narvor, N. L.; Toupet, L.; Lapinte, C. J . Am. Chem. Soc. 1995,
117, 7129. (c) Laidlaw, W. M.; Denning, R. G. J . Chem. Soc., Dalton
Trans. 1994, 1987. (d) Heck, J .; Brussaard, H. C.; Dabek, S.; Meyer-
Friedrichsen, T.; Wong, H. SPIE 1997, 3147, 53. (e) Ribou, A.-C.;
Launay, J .-P.; Sachtleben, M. L.; Li, H.; Spangler, C. W. Inorg. Chem.
1996, 35, 3735. (f) Spotts, J . M.; Schaefer, W. P.; Marder, S. R. Adv.
Mater. 1992, 4, 100. (g) Lambert, C.; No˜ll, G. Angew. Chem., Int. Ed.
Engl. 1998, 37, 2107.
accordance with this trend: 7 > 5 > 3, in order of
decreasing λmax. Therefore, the dialkylamino moiety
helps to stabilize the trityl cations at the expense of λmax
.
(25) (a) Lewis, G. N.; Calvin, M. Chem. Rev. 1939, 25, 273. (b) Lewis,
G. N.; Bigeleisen, J . J . Am. Chem. Soc. 1943, 65, 2102. (c) Nakatsuji,
S.; Okamoto, N.; Nakashima, K.; Akiyama, S. Chem. Lett. 1986, 329.
(26) Ito, S.; Kobayashi, H.; Kikuchi, S.; Morita, N.; Asao, T. Bull.
Chem. Soc. J pn. 1996, 69, 3225.
(28) Bruce, M. I.; Humphrey, M. G.; Snow, M. R.; Tiekink, E. R. T.
J . Organomet. Chem. 1986, 314, 213.

Crystal Violet Analogues
Con clu sion
Organometallics, Vol. 18, No. 3, 1999 327
thenium σ-acetylide moiety also leads to stable near-
infrared dyes.29
We have synthesized several organoruthenium ana-
logues of crystal violet. We found that incorporation of
dialkylamino and “Cp(PPh3)2Ru(CtC)” substituents on
the phenyl rings of the triphenylcarbenium ion resulted
in the formation of stable organoruthenium near-
infrared absorbers. In addition, incorporation of thiophene
rings increases the λmax as well as the oscillating
strength of the complexes. Further research in this area
to fine-tune λmax and enhance the f values is currently
under investigation. Preliminary results indicate that
substitution of the ferrocenylvinyl moiety for the ru-
Ack n ow led gm en t. This work was supported by the
Academia Sinica.
Su p p or tin g In for m a tion Ava ila ble: Tables of atomic
coordinates and thermal parameters, all bond distances and
angles, and experimental data for X-ray diffraction studies of
1‚CH2Cl2. This material is available free of charge via the
Internet at http://pubs.acs.org.
(29) J ustin Thomas, K. R.; Lin, J . T. Unpublished research.
OM980853O