Synthesis, structure, and liquid crystal properties of a series of platinum(II) complexes containing chiral 4-(4-alkoxyphenylethynyl) phenylisocyanide ligands

Article abstract of DOI:10.1016/S0022-328X(03)00763-0

Several platinum(II) isocyanide complexes of the type PtI₂ (CNC₆H₂-2,6-R₂-4-CC-(C₆ H₂-3,5-R′₂-4-(R or S )-OCHMeC_n-1 (H_2(n-1)CH₃))₂ have been prepared and their mesomorphic properties have been investigated. The complexes with R=Me, R′=H, and n=4-7 exhibit a broader N* phase than the corresponding complexes with R=R′=H, indicating that the methyl substituents on the phenylisocyanide group improve the liquid crystal properties by creating a smooth transition between the bulky PtI₂ center and the more slender organic units. The complexes with R=Me and R′=Me exhibit a SmA phase. The presence of methyl groups in the R′-positions in addition to the methyl groups in the R-positions increases the melting point, but does not significantly change the clearing temperature. For the complexes with R=Me and R′=H the temperature-dependent pitches of the N* phase range from 350 to 400 nm.

Full text of DOI:10.1016/S0022-328X(03)00763-0

Journal of Organometallic Chemistry 684 (2003) 287Á299
/
www.elsevier.com/locate/jorganchem
Synthesis, structure, and liquid crystal properties of a series of
platinum(II) complexes containing chiral 4-(4-alkoxyphenylethynyl)
phenylisocyanide ligands
Andreas Mayr a,*, Shuangxi Wang b, Kung-Kai Cheung b, Maochun Hong c
a Department of Chemistry, State University of New York at Stony Brook, Stony Brook, NY 11794-3400, USA
b Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong
c Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002, People’s Republic of China
Received 14 March 2003; received in revised form 18 July 2003; accepted 18 July 2003
Dedicated to Prof. E.O. Fischer on the occasion of his 85th birthday
Abstract
?
Several platinum(II) isocyanide complexes of the type PtI2(CNC6H2-2,6-R2-4-CC-(C6H2-3,5-R2-4-(R or S)-OCHMeCnꢀ1(H2
(nꢀ1)CH3))2 have been prepared and their mesomorphic properties have been investigated. The complexes with RꢁMe, R?ꢁH, and
nꢁ4Á7 exhibit a broader N* phase than the corresponding complexes with RꢁR?ꢁH, indicating that the methyl substituents on
the phenylisocyanide group improve the liquid crystal properties by creating a smooth transition between the bulky PtI2 center and
the more slender organic units. The complexes with RꢁMe and R?ꢁMe exhibit a SmA phase. The presence of methyl groups in the
R?-positions in addition to the methyl groups in the R-positions increases the melting point, but does not significantly change the
/
/
/
/
/
/
/
/
clearing temperature. For the complexes with Rꢁ
/
Me and R?ꢁ/H the temperature-dependent pitches of the N* phase range from
350 to 400 nm.
# 2003 Elsevier B.V. All rights reserved.
Keywords: Platinum(II) isocyanide complex; Liquid crystals
1. Introduction
We have recently prepared palladium and platinum
complexes of the same general type based on 4-
isocyanobenzylidene-4-alkoxyphenylimines [18]. Com-
plexes I are distinguished from other mesomorphic
isocyanide metal complexes primarily by the presence
of the imine bridge between the aromatic rings and the
lateral methyl substituents on the isocyanophenyl
groups. The imine linkage provides a convenient means
of assembling the elongated rigid core, but its hydrolytic
ability also limits the potential utility of the liquid
crystals. In the present complexes 1, we replaced the
imino bridge by the hydrolytically stable, but sterically
similar ethynylene connector. The lateral methyl sub-
stituents on the isocyanide ligands in complexes I were
suggested to have a favorable influence on the liquid
crystal properties, by smoothing out the protrusions
created by the lateral iodide ligands. In order to evaluate
this notion, we included in this study also isocyanides
without methyl substituents and isocyanides with addi-
Linear metal complexes of isocyanides with rigid
central cores and flexible terminal chains have been
demonstrated by Takahashi and coworkers [1Á
Espinet and coworkers [5Á16] to exhibit liquid crystal
/
4] and by
/
properties. In typical examples, the rigid cores of the
isocyanides contain one or several phenyl rings while
alkoxy groups form the flexible chains. By introducing
chiral alkoxy groups, Serrano, Veciana and coworkers
have furthermore shown that metal complexes of this
type can form ferroelectric liquid crystals [17], and
Espinet and coworkers were able to obtain complexes
exhibiting twist-grain boundaries and blue phases [15].
* Corresponding author. Tel.: ꢂ
960.
E-mail address: amayr@notes.cc.sunysb.edu (A. Mayr).
/
1-631-6327-951; fax: ꢂ1-631-6327-
/
0022-328X/03/$ - see front matter # 2003 Elsevier B.V. All rights reserved.
doi:10.1016/S0022-328X(03)00763-0

288
A. Mayr et al. / Journal of Organometallic Chemistry 684 (2003) 287Á299
/
tional methyl substituents on the second aromatic ring.
The results confirm that the lateral methyl substituents
on the isocyanophenyl groups indeed exert a beneficial
influence on the liquid crystal properties.
dimethylphenol [19,20]. 4-Ethynylaniline and 4-ethynyl-
2,6-dimethylaniline [21] were prepared from the corre-
sponding 4-iodoanilines via palladium(0)Ácopper(I)-cat-
/
alyzed coupling with trimethylsilylacetylene, followed by
hydrolytic desilylation [22]. The compounds (R)- or (S)-
As a further modification, we introduced chiral 1-
methylalkoxy chains in complexes 1. Complexes I were
found to exhibit a nematic (N) and/or a smectic C (SmC)
phase, the latter covering a broad temperature range.
The observation of a broad SmC phase suggested to us
that analogues with chiral alkoxy groups might exhibit a
chiral smectic C (Sm*C) phase. However, this expecta-
tion could not be confirmed in the present study,
presumably because the alkoxy chains of complexes 1
are too short. For the chain lengths covered in this study
4-I-2,6-R2-C6H2-OC*(Me)H-Cnꢀ1H2(nꢀ1)ꢂ2 (nꢁ
/
4Á7,
/
RꢁH, Me) were prepared from the corresponding
/
alcohols and phenols following an established literature
procedure [23]. All of the ligands and their metal
complexes were prepared in the same manner as out-
lined in Scheme 1. Typical preparative procedures and
physical data for intermediates, ligands, and metal
complexes are given below.
(nꢁ
/
4Á7) both complexes I and 1 exhibit only nematic
/
2.1. Synthesis of anilines 2
phases, N and N*, respectively.
2.1.1. (R)-4-(4-(1-methylheptyloxy)phenylethynyl)-
2,6-dimethylaniline (2e)
2. Experimental
Under an atmosphere of nitrogen, a 100 ml flask is
charged with (R)-4-iodo-(1-methylheptyloxy)benzene
(664 mg, 2 mmol), 4-ethynyl-2,6-dimethylaniline (290
mg, 2 mmol), bis(triphenylphosphine)palladium dichlor-
ide (28.6 mg) and copper (I) iodide (57 mg) [24]. Then
triethylamine (60 ml) is added, and the reaction mixture
1
The H- and 13C-NMR spectra were recorded on a
Bruker DPX 300 or a JEOL 270 NMR spectrometer,
using tetramethylsilane as internal standard. IR spectra
were measured in CH2Cl2 solution using a Shimadzu
FTIR-8201PC infrared spectrophotometer. Mass spec-
tra were obtained with a Finnigan MAT 95 MS
spectrometer. The textures of the mesophases were
studied with a Leica polarizing microscope equipped
with a Mettler FP82 hot stage. The transition tempera-
tures were obtained by differential scanning calorimetry
is stirred at 50Á
under reduced pressure. The residue is extracted with
dichloromethane (3ꢃ100 ml). After evaporation of the
solvent, the product is purified by chromatography on
silica gel, using hexaneÁethyl acetate (3:1/v:v) as the
eluent, to afford 430 mg (62%) of an orange oil. H-
NMR (CDCl3): d 7.39 (2H, d, Jꢁ8.9 Hz, ArÁH), 7.13
(2H, s, ArÁH), 6.82 (2H, d, Jꢁ8.9 Hz, ArÁH), 4.33
(1H, m, CHMe2), 3.73 (2H, br, NH2), 2.17 (6H, s, CH3)
1.73Á1.28 (13H, m, C5H10, CH3), 0.88 (3H, m, CH3). IR
(CH2Cl2, cmꢀ1): 3404 (NÁ
H), 2206 (CÅC). MS (EI):
349 (M).
/
70 8C for 24 h. The solvent is removed
/
/
1
using a PerkinÁElmer DSC7 instrument with heating
/
rates of 10 K minꢀ1 under a nitrogen atmosphere.
Elemental microanalyses were performed by Butter-
worth Laboratories Ltd.
/
/
/
/
/
The reflectance spectra were measured in the follow-
ing way: A few milligrams of a sample were dropped
onto a cleaned glass substrate and heated to the
temperature of the liquid crystal phase. Then, a cleaned
microscopy cover glass was carefully placed on top of
the sample and gently pressed to create a flow-induced
alignment. After the alignment test cell was cooled to
room temperature, it was transferred to a polarizing
microscope, and the reflective spectrum was measured
with an ORIEL MS257 imaging spectrometer connected
to the crossed polarizer microscope via an optic fiber.
The temperature of the sample was controlled with a
Mettler FP82 hot stage. The data were analyzed using
ORIEL Instaspec software.
/
/
/
2.1.2. (R)-4-(4-(1-Methylbutyloxy)phenylethynyl)-2,6-
dimethylaniline (2a)
1
Orange oil. Yield: 67%. H-NMR (CDCl3): d 7.39
(2H, d, Jꢁ
(2H, d, Jꢁ8.9 Hz, ArÁ
(2H, br, NH2), 2.17 (6H, s, CH3) 1.75Á
C2H4, CH3), 0.88 (3H, m, CH3). IR (CH2Cl2, cmꢀ1):
3408 (NÁH), 2216 (CÅC). MS (EI): 307 (M).
/
8.9 Hz, ArÁ
H), 4.34 (1H, m, CHMe2), 3.77
1.28 (7H, m,
/
H), 7.13 (2H, s, ArÁH), 6.82
/
/
/
/
/
/
Methylene chloride, n-hexane, and triethylamine were
dried over calcium hydride and distilled prior to use. All
other solvents and reagents were used as received. 4-
Iodoaniline, 4-iodophenol, (R)- and (S)-2-hexanol, (R)-
2-pentanol, (S)-2-heptanol, and (R)- and (S)-2-octanol
were obtained from Aldrich or Acros. 4-Iodo-2,6-
dimethylaniline and 4-iodo-2,6-dimethylphenol were
prepared by iodination of 2,6-dimethylaniline and 2,6-
2.1.3. (R)-4-(4-(1-Methylpentyloxy)phenylethynyl)-
2,6-dimethylaniline (2b)
1
Orange oil. Yield: 60%. H-NMR (CDCl3): d 7.39
(2H, d, Jꢁ
(2H, d, Jꢁ8.9 Hz, ArÁ
(2H, br, NH2), 2.17 (6H, s, CH3) 1.73Á
C3H6, CH3), 0.88 (3H, m, CH3). IR (CH2Cl2, cmꢀ1):
3408 (NÁH), 2205 (CÅC). MS (EI): 321 (M).
/
8.9 Hz, ArÁ
H), 4.33 (1H, m, CHMe2), 3.73
1.28 (9H, m,
/
H), 7.13 (2H, s, ArÁH), 6.82
/
/
/
/
/
/

A. Mayr et al. / Journal of Organometallic Chemistry 684 (2003) 287Á
/299
289
Scheme 1.
2.1.4. (S)-4-(4-(1-Methylpentyloxy)phenylethynyl)-
2,6-dimethylaniline (2c)
2.1.7. (R)-4-(4-(1-
Methylpentyloxy)phenylethynyl)aniline (2g)
1
Orange oil. Yield: 60%. H-NMR (CDCl3): d 7.39
1
Orange oil. Yield: 66%. H-NMR (CDCl3): d 7.40
(2H, d, Jꢁ8.8 Hz, ArÁH), 7.31 (2H, d, Jꢁ8.6 Hz, ArÁ
H), 6.83 (2H, d, Jꢁ8.8 Hz, ArÁH), 6.63 (2H, Jꢁ8.5
Hz, ArÁH), 4.36 (1H, m, CHMe2), 3.77 (2H, br, NH2),
1.74Á1.26 (9H, m, C3H6, CH3), 0.88 (3H, m, CH3). IR
(CH2Cl2, cmꢀ1): 3404 (NÁ
H), 2206 (CÅC). MS (EI):
(2H, d, Jꢁ
(2H, d, Jꢁ8.9 Hz, ArÁ
(2H, br, NH2), 2.17 (6H, s, CH3) 1.73Á
C3H6, CH3), 0.88 (3H, m, CH3). IR (CH2Cl2, cmꢀ1):
3408 (NÁH), 2205 (CÅC). MS (EI): 321 (M).
/
8.9 Hz, ArÁ
H), 4.33 (1H, m, CHMe2), 3.73
1.28 (9H, m,
/
H), 7.13 (2H, s, ArÁ
/
H), 6.82
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
296 (M).
2.1.5. (S)-4-(4-(1-Methylhexyloxy)phenylethynyl)-2,6-
dimethylaniline (2d)
2.1.8. (S)-4-(4-(1-
Methylhexyloxy)phenylethynyl)aniline (2h)
1
Orange oil. Yield: 58%. H-NMR (CDCl3): d 7.39
(2H, d, Jꢁ
(2H, d, Jꢁ8.9 Hz, ArÁ
(2H, br, NH2), 2.16 (6H, s, CH3) 1.73Á
C4H8, CH3), 0.88 (3H, m, CH3). IR (CH2Cl2, cmꢀ1):
3409 (NÁH), 2206 (CÅC). MS (EI): 335 (M).
/
8.9 Hz, ArÁ
H), 4.33 (1H, m, CHMe2), 3.73
1.28 (11H, m,
/
H), 7.13 (2H, s, ArÁ
/
H), 6.82
Yellow oil. Yield: 62%. 1H-NMR (CDCl3): d 7.40
/
/
(2H, d, Jꢁ
H), 6.83 (2H, d, Jꢁ
Hz, ArÁH), 4.36 (1H, m, CHMe2), 3.75 (2H, br, NH2),
1.74Á1.28 (11H, m, C4H8, CH3), 0.88 (3H, m, CH3). IR
(CH2Cl2, cmꢀ1): 3404 (NÁ
H), 2206 (CÅC). MS (EI):
/
8.8 Hz, ArÁ
/
H), 7.31 (2H, d, Jꢁ
/
8.6 Hz, ArÁ
/
/
/
8.8 Hz, ArÁ
/
H), 6.63 (2H, Jꢁ
/8.5
/
/
/
/
/
/
310 (M).
2.1.6. (S)-4-(4-(1-Methylheptyloxy)phenylethynyl)-
2,6-dimethylaniline (2f)
1
Orange oil. Yield: 58%. H-NMR (CDCl3): d 7.39
2.1.9. (R)-4-(4-(1-
Methylheptyloxy)phenylethynyl)aniline (2i)
(2H, d, Jꢁ
(2H, d, Jꢁ8.9 Hz, ArÁ
(2H, br, NH2), 2.17 (6H, s, CH3) 1.73Á
C5H10, CH3), 0.88 (3H, m, CH3). IR (CH2Cl2, cmꢀ1):
3409 (NÁH), 2205 (CÅC). MS (EI): 349 (M).
/
8.9 Hz, ArÁ
H), 4.33 (1H, m, CHMe2), 3.73
1.28 (13H, m,
/
H), 7.13 (2H, s, ArÁ
/
H), 6.82
1
Orange oil. Yield: 71%. H-NMR (CDCl3): d 7.40
/
/
/
(2H, d, Jꢁ
H), 6.82 (2H, d, Jꢁ
Hz, ArÁH), 4.35 (1H, m, CHMe2), 3.77 (2H, br, NH2),
/
8.7 Hz, ArÁ
/
H), 7.31 (2H, d, Jꢁ
/
8.6 Hz, ArÁ
/
/
8.8 Hz, ArÁ
/
H), 6.61 (2H, Jꢁ
/8.5
/
/
/

290
A. Mayr et al. / Journal of Organometallic Chemistry 684 (2003) 287Á299
/
1.74Á
/
1.28 (13H, m, C5H10, CH3), 0.88 (3H, m, CH3). IR
(CH2Cl2, cmꢀ1): 3404 (NÁ
324 (M).
2.2.2. (R)-4-(4-(1-Methylbutyloxy)phenylethynyl)-2,6-
dimethyl-1-formamidobenzene (3a)
1
Yellow solid. Yield: 96%. H-NMR (CDCl3): d 8.41,
/
H), 2208 (CÅC). MS (EI):
/
8.13, 8.09 (1H, s, NHCHO), 7.44, 7.41 (2H, s, ArÁ
7.28, 7.24 (2H, s, ArÁH), 7.14, 7.10, 6.89, 6.87 (1H, br,
NHCHO), 6.86, 6.85, 6.83, 6.82 (2H, s, ArÁH), 4.36
(1H, m, CH(Me)), 2.29, 2.25 (6H, s, CH3) 1.79Á1.29
(7H, m, C2H4, CH3), 0.88 (3H, m, CH3). IR (CH2Cl2,
cmꢀ1): 3404 (NÁ
H), 2208(CÅC), 1699 (CÄO). MS (EI):
335 (M).
/
H),
2.1.10. (S)-4-(4-(1-
/
Methylheptyloxy)phenylethynyl)aniline (2j)
1
Orange oil. Yield: 66%. H-NMR (CDCl3): d 7.40
/
/
(2H, d, Jꢁ
H), 6.83 (2H, d, Jꢁ
Hz, ArÁH), 4.36 (1H, m, CHMe2), 3.77 (2H, br, NH2),
1.74Á1.26 (13H, m, C5H10, CH3), 0.88 (3H, m, CH3). IR
(CH2Cl2, cmꢀ1): 3404 (NÁ
H), 2206 (CÅC). MS (EI):
324 (M).
/
8.8 Hz, ArÁ
/
H), 7.31 (2H, d, Jꢁ
/
8.6 Hz, ArÁ
/
/
8.8 Hz, ArÁ
/
H), 6.63 (2H, Jꢁ
/
8.5
/
/
/
/
/
/
/
2.2.3. (R)-4-(4-(1-Methylpentyloxy)phenylethynyl)-
2,6-dimethyl-1-formamidobenzene (3b)
1
Yellow solid. Yield: 98%. H-NMR (CDCl3): d 8.39,
2.1.11. (S)-4-(4-(1-Methylhexyloxy)-2,6-
dimethylphenylethynyl)-2,6-dimethylaniline (2k)
1
Orange oil. Yield: 64%. H-NMR (CDCl3): d 7.15
8.12, 8.08 (1H, s, NHCHO), 7.44, 7.41 (2H, s, ArÁ
7.28, 7.24 (2H, s, ArÁH), 7.14, 7.10, 6.89, 6.87 (1H, br,
NHCHO), 6.86, 6.85, 6.83, 6.82 (2H, s, ArÁH), 4.36
(1H, m, CHMe2), 2.29, 2.23 (6H, s, CH3) 1.73Á1.29 (9H,
m, C3H6, CH3), 0.88 (3H, m, CH3). IR (CH2Cl2, cmꢀ1):
3418 (NÁH), 2216 (CÅC), 1699 (CÄO). MS (EI): 349
(M).
/
H),
/
/
(2H, s, ArÁ
Hz, ArÁH), 4.07 (1H, m, CHMe2), 3.71 (2H, br, NH2),
2.23 (6H, s, CH3), 2.15(6H, s, CH3), 1.78Á1.28 (13H, m,
C4H8, CH3), 0.88 (3H, m, CH3). IR (CH2Cl2, cmꢀ1):
3404 (NÁH), 2208 (CÅC). MS (EI):363 (M).
/
H), 7.12 (2H, s, ArÁ
/
H), 6.82 (2H, d, Jꢁ8.9
/
/
/
/
/
/
/
/
/
2.1.12. (R)-4-(4-(1-Methylheptyloxy)-2,6-
dimethylphenylethynyl)-2,6-dimethylaniline (2l)
1
Orange oil. Yield: 75%. H-NMR (CDCl3): d 7.15
2.2.4. (S)-4-(4-(1-Methylpentyloxy)phenylethynyl)-
2,6-dimethyl-1-formamidobenzene (3c)
1
Yellow solid. Yield: 96%. H-NMR (CDCl3): d 8.39,
(2H, s, ArÁ
Hz, ArÁH), 4.07 (1H, m, CHMe2), 3.71 (2H, br, NH2),
2.23 (6H, s, CH3), 2.15(6H, s, CH3), 1.78Á1.28 (13H, m,
C5H10, CH3), 0.88 (3H, m, CH3). IR (CH2Cl2, cmꢀ1):
3404 (NÁH), 2202 (CÅC). MS (EI): 377 (M).
/
H), 7.12 (2H, s, ArÁ
/
H), 6.82 (2H, d, Jꢁ
/
8.9
8.12, 8.08 (1H, s, NHCHO), 7.44, 7.41 (2H, s, ArÁ
7.28, 7.24 (2H, s, ArÁH), 7.14, 7.10, 6.89, 6.87 (1H, br,
NHCHO), 6.86, 6.85, 6.83, 6.82 (2H, s, ArÁH), 4.36
(1H, m, CHMe2), 2.29, 2.23 (6H, s, CH3) 1.73Á1.29 (9H,
m, C3H6, CH3), 0.88 (3H, m, CH3). IR (CH2Cl2, cmꢀ1):
3418 (NÁH), 2216 (CÅC), 1699 (CÄO). MS (EI): 349
(M).
/
H),
/
/
/
/
/
/
/
/
/
/
2.2. Synthesis of formamides 3
2.2.1. (R)-4-(4-(1-Methylheptyloxy)phenylethynyl)-
2,6-dimethyl-1- formamidobenzene (3e)
A mixture of acetic anhydride (1.46 g, 14.4 mmol) and
formic acid (0.66 g, 14.4 mmol) is heated for 2 hours at
2.2.5. (S)-4-(4-(1-Methylhexyloxy)phenylethynyl)-2,6-
dimethyl-1-formamidobenzene (3d)
1
Yellow solid. Yield: 98%. H-NMR (CDCl3): d 8.39,
8.12, 8.08(1H, s, NHCHO), 7.44, 7.41 (2H, s, ArÁ
7.28, 7.24 (2H, s, ArÁH), 7.14, 7.10, 6.89, 6.87 (1H, br,
NHCHO), 6.86, 6.85, 6.83, 6.82 (2H, s, ArÁH), 4.36
(1H, m, CHMe2), 2.29, 2.23 (6H, s, CH3) 1.73Á1.29
(11H, m, C4H8, CH3), 0.88 (3H, m, CH3). IR (CH2Cl2,
cmꢀ1): 3417 (NÁ
H), 2212 (CÅC), 1697 (CÄO). MS (EI):
363 (M).
/
H),
50Á60 8C in a flask fitted with a drying tube [25].
/
/
Compound 2e (2.35 g, 6.8 mmol) is added to the stirred
mixture over a 10-min period, using a water bath to
maintain the temperature below 39 8C. After stirring for
about 24 h at r.t., CH2Cl2 and water (50 ml/50 ml) are
added. The organic phase is treated with 10% Na2CO3
(aq) and dried with magnesium sulfate. After removal of
the solvent on a rotary evaporator, the residue is
purified by chromatography on silica gel, using
/
/
/
/
/
2.2.6. (S)-4-(4-(1-Methylheptyloxy)phenylethynyl)-
2,6-dimethyl-1-formamidobenzene (3f)
1
Yellow solid. Yield: 98%. H-NMR (CDCl3): d 8.39,
hexaneÁ
/
ethyl acetate (1:1/v:v) as the eluent, to afford
2.48 g (yield: 97%) of a yellow solid. 1H-NMR (CDCl3):
d 8.39, 8.12, 8.08 (1H, s, NHCHO), 7.44, 7.41 (2H, s,
8.12, 8.08(1H, s, NHCHO), 7.44, 7.41 (2H, s, ArÁ
7.28, 7.24 (2H, s, ArÁH), 7.14, 7.10, 6.89, 6.87 (1H, br,
NHCHO), 6.86, 6.85, 6.83, 6.82 (2H, s, ArÁH), 4.36
(1H, m, CHMe2), 2.29, 2.23 (6H, s, CH3) 1.73Á1.29
(13H, m, C5H10, CH3), 0.88 (3H, m, CH3). IR (CH2Cl2,
cmꢀ1): 3417 (NÁ
H), 2206 (CÅC), 1699 (CÄO). MS (EI):
377 (M).
/
H),
ArÁ
(1H, br, NHCHO), 6.86, 6.85, 6.83, 6.82 (2H, s, ArÁ
4.36 (1H, m, CHMe2), 2.29, 2.23 (6H, s, CH3) 1.73Á1.29
(13H, m, C5H1, CH3), 0.88 (3H, m, CH3). IR (CH2Cl2,
cmꢀ1): 3404 (NÁ
H), 2208 (CÅC), 1697 (CÄO). MS (EI):
377 (M).
/
H), 7.28, 7.24 (2H, s, ArÁ/H), 7.14, 7.10, 6.89, 6.87
/
/H),
/
/
/
/
/
/
/
/
/

A. Mayr et al. / Journal of Organometallic Chemistry 684 (2003) 287Á
/299
291
2.2.7. (R)-4-(4-(1-Methylpentyloxy)phenylethynyl)-1-
formamidobenzene (3g)
2.2.12. (R)-4-(4-(1-Methylheptyloxy)-2,6-
dimethylphenylethynyl)-2,6-dimethyl-1-
formamidobenzene (3l)
1
Yellow solid. Yield: 92%. H-NMR (CDCl3): d 8.74,
1
8.72, 8.39, 8.38, 7.84, 7.82 (1H, s, NHCHO), 7.05, 7.04
(1H, br, NHCHO), 7.54, 7.52, 7.50, 7.49, 7.48, 7.47,
Yellow solid: Yield: 97%. H-NMR (CDCl3): d 8.39,
8.12, 8.08 (1H, s, NHCHO), 7.26, 7.24, 7.18(4H, s, ArÁ
H), 7.08, 7.03, 6.87 (1H, br, NHCHO), 4.07 (1H, m,
CHMe2), 2.25, 2.24 (12H, s, CH3) 1.79Á1.17 (13H, m,
C5H10, CH3), 0.89 (3H, m, CH3). IR (CH2Cl2, cmꢀ1):
3406 (NÁH), 2208 (CÅC), 1697 (CÄO). MS (EI): 405
(M).
/
7.44, 7.42, (6H, s, ArÁ
H), 4.36 (1H, m, CHMe2), 2.29, 2.23 (6H, s, CH3) 1.73Á
1.25 (9H, m, C3H6, CH3), 0.88 (3H, m, CH3). IR
(CH2Cl2, cmꢀ1): 3415 (NÁ
H), 2216 (CÅC), 1703 (CÄ
O). MS (EI): 321 (M).
/
H), 6,85, 6.84, 6.83, (2H, s, ArÁ
/
/
/
/
/
/
/
/
/
2.3. Synthesis of isocyanides 4
2.2.8. (S)-4-(4-(1-Methylhexyloxy)phenylethynyl)-1-
formamidobenzene (3h)
Yellow solid. Yield: 96%. H-NMR (CDCl3): d 8.74,
8.73, 8.39, 8.38, 7.84, 7.83 (1H, s, NHCHO), 7.05, 7.04
(1H, br, NHCHO), 7.54, 7.52, 7.51, 7.49, 7.48, 7.47,
2.3.1. (R)-4-(4-(1-Methylheptyloxy)phenylethynyl)-
2,6-dimethylphenylisocyanide (4e)
1
A flask containing 3e (900 mg, 2.4 mmol), triethyla-
mine (0.12 ml, 0.8 mmol), and CH2Cl2 (50 ml) is cooled
in a liquid nitrogen bath. Then a solution of triphosgene
(37.2 mg, 0.8 mmol) in dry CH2Cl2 (5 ml) is added
slowly [26]. The reaction mixture is allowed to warm to
r.t. and stirred for 12 h. Then 10% Na2CO3 (aq) (30 ml)
is added dropwise. The organic phase is separated and
dried with MgSO4. The solvent is evaporated, and the
crude product is chromatographed on silica gel, using
7.44, 7.43, (6H, s, ArÁ
H), 4.36 (1H, m, CHMe2), 2.29, 2.23 (6H, s, CH3) 1.73Á
1.25 (11H, m, C4H8, CH3), 0.88 (3H, m, CH3). IR
(CH2Cl2, cmꢀ1): 348 (NÁ
H), 2206 (CÅC), 1705 (CÄO).
MS (EI): 335 (M).
/
H), 6,85, 6.84, 6.83, (2H, s, ArÁ
/
/
/
/
/
2.2.9. (R)-4-(4-(1-Methylheptyloxy)phenylethynyl)-1-
formamidobenzene (3i)
hexaneÁ
610 mg (71%) of 4e as an orange oil. 1H-NMR (CDCl3):
d 7.42 (2H, d, Jꢁ8.8 Hz, ArÁH), 7.24 (2H, s, ArÁH),
6.84 (2H, d, Jꢁ8.8 Hz, ArÁH), 4.37 (1H, m, CHMe2),
2.41 (6H, s, ArÁCH3), 1.73Á1.25 (13H, m, C5H10, CH3),
/ethyl acetate (10:1 v/v) as the eluent, to afford
1
Yellow solid. Yield: 95%. H-NMR (CDCl3): d 8.74,
8.72, 8.39, 8.38, 7.84, 7.82 (1H, s, NHCHO), 7.05, 7.04
(1H, br, NHCHO), 7.54, 7.52, 7.50, 7.49, 7.48, 7.47,
/
/
/
/
/
7.44, 7.42, (6H, s, ArÁ
H), 4.36 (1H, m, CHMe2), 2.29, 2.23 (6H, s, CH3) 1.73Á
1.25 (13H, m, C5H10, CH3), 0.88 (3H, m, CH3). IR
(CH2Cl2, cmꢀ1): 3415 (NÁ
H), 2216 (CÅC), 1703 (CÄ
O). MS (EI): 349 (M).
/
H), 6,85, 6.84, 6.83, (2H, s, ArÁ
/
/
/
/
0.88 (3H, m, CH3). 13C-NMR (CDCl3): d 168.9, 158.9,
134.9, 133.2, 130.6, 126.5, 124.3, 115.7, 114.3, 91.6, 86.9,
74.1, 36.4, 31.8, 29.3, 25.5, 22.6, 19.7, 18.9, 14.2. IR
/
/
/
(CH2Cl2, cmꢀ1): 2212 (CÅ
359 (M).
/
C), 2118 (CÅ
/
N). MS (EI):
2.2.10. (S)-4-(4-(1-Methylheptyloxy)phenylethynyl)-1-
formamidobenzene (3j)
2.3.2. (R)-4-(4-(1-Methylbutyloxy)phenylethynyl)-2,6-
dimethylphenylisocyanide (4a)
1
Yellow solid. Yield: 96%. H-NMR (CDCl3): d 8.74,
1
Light yellow oil. Yield: 73%. H-NMR (CDCl3): d
8.72, 8.40, 8.39, 7.84, 7.82 (1H, s, NHCHO), 7.05, 7.04
(1H, br, NHCHO), 7.54, 7.52, 7.51, 7.49, 7.48, 7.47,
7.42 (2H, d, Jꢁ
(2H, d, Jꢁ8.8 Hz, ArÁ
(6H, s, ArÁCH3), 1.75Á
/
8.8 Hz, ArÁ
H), 4.39 (1H, m, CHMe2), 2.41
1.25 (7H, m, C2H4, CH3), 0.94
/
H), 7.24 (2H, s, ArÁ
/
H), 6.85
/
/
7.44, 7.43, (6H, s, ArÁ
H), 4.36 (1H, m, CHMe2), 2.29, 2.23 (6H, s, CH3) 1.73Á
1.26 (13H, m, C5H10, CH3), 0.88 (3H, m, CH3). IR
(CH2Cl2, cmꢀ1): 3415 (NÁ
H), 2216 (CÅC), 1699 (CÄ
O). MS (EI): 349 (M).
/
H), 6,85, 6.84, 6.83, (2H, s, ArÁ
/
/
/
/
(3H, m, CH3). 13C-NMR (CDCl3): d 168.9, 158.7, 134.9,
133.2, 130.6, 124.3, 115.8, 114.3, 91.6, 86.9, 73.7, 38.5,
29.7, 22.7, 19.7, 18.8, 18.7, 14.0. IR (CH2Cl2, cmꢀ1):
/
/
/
2210 (CÅ
/
C), 2117 (CÅ/N). MS (EI): 317 (M).
2.2.11. (S)-4-(4-(1-Methylhexloxy-2,6-
dimethyl)phenylethynyl)-2,6-dimethyl-1-
formamidobenzene (3k)
2.3.3. (R)-4-(4-(1-Methylpentyloxy)phenylethynyl)-
2,6-dimethylphenylisocyanide (4b)
1
Light yellow oil. Yield: 74%. H-NMR (CDCl3): d
1
Yellow solid: Yield: 96%. H-NMR (CDCl3): d 8.39,
7.42 (2H, d, Jꢁ
(2H, d, Jꢁ8.8 Hz, ArÁ
(6H, s, ArÁCH3), 1.73Á
/
8.8 Hz, ArÁ
H), 4.37 (1H, m, CHMe2), 2.41
1.25 (9H, m, C3H6, CH3), 0.88
/
H), 7.24 (2H, s, ArÁ
/
H), 6.85
8.12, 8.08 (1H, s, NHCHO), 7.26, 7.24, 7.18 (4H, s, ArÁ
H), 7.08, 7.03, 6.87 (1H, br, NHCHO), 4.07 (1H, m,
CHMe2), 2.25, 2.24 (12H, s, ÁCH3) 1.79Á1.17 (11H, m,
C4H8, CH3), 0.89 (3H, m, CH3). IR (CH2Cl2, cmꢀ1):
3406 (NÁH), 2202(CÅC), 1699 (CÄO). MS (EI): 391
(M).
/
/
/
/
/
/
/
(3H, m, CH3). 13C-NMR (CDCl3): d 168.9, 158.7, 134.9,
133.2, 130.6, 126.4, 124.3, 115.8, 114.3, 91.6, 86.9, 74.0,
36.4, 27.7, 22.7, 19.7, 18.8, 14.0. IR (CH2Cl2, cmꢀ1):
/
/
/
2212 (CÅ
/
C), 2117 (CÅ/N). MS (EI): 331 (M).

292
A. Mayr et al. / Journal of Organometallic Chemistry 684 (2003) 287Á299
/
2.3.4. (S)-4-(4-(1-Methylpentyloxy)phenylethynyl)-
2,6-dimethylphenylisocyanide (4c)
1
Light yellow oil. Yield: 76%. H-NMR (CDCl3): d
2.3.9. (R)-4-(4-(1-
Methylheptyloxy)phenylethynyl)phenylisocyanide (4i)
1
Light yellow soild. Yield: 75%. H-NMR (CDCl3): d
7.42 (2H, d, Jꢁ
(2H, d, Jꢁ8.8 Hz, ArÁ
(6H, s, ArÁCH3), 1.73Á
/
8.8 Hz, ArÁ
H), 4.37 (1H, m, CHMe2), 2.41
1.25 (9H, m, C3H6, CH3), 0.88
/
H), 7.24 (2H, s, ArÁ
/
H), 6.85
7.51 (2H, d, Jꢁ
ArÁH), 7.31 (2H, d, Jꢁ
Jꢁ8.8 Hz, ArÁ
/
8.5 Hz, ArÁ
/
H), 7.44 (2H, d, Jꢁ
H), 6.86 (2H, d,
1.24
/
8.8 Hz,
/
/
/
/
8.5 Hz, ArÁ
/
/
/
/
/
H), 4.39 (1H, m, CHMe2), 1.74Á
/
(3H, m, CH3). 13C-NMR (CDCl3): d 168.9, 158.7, 134.9,
133.2, 130.6, 126.4, 124.3, 115.8, 114.3, 91.6, 86.9, 74.0,
36.4, 27.7, 22.7, 19.7, 18.8, 14.0. IR (CH2Cl2, cmꢀ1):
(13H, m, C5H10, CH3), 0.88 (3H, m, CH3). 13C-NMR
(CD2Cl2): d 165.4, 158.8, 133.2, 132.3, 126.4, 125.2,
115.7, 113.9, 92.6, 86.5, 73.9, 36.4, 31.8, 29.2, 25.5, 22.6,
2212 (CÅ
/
C), 2117 (CÅ
/
N). MS (EI): 331 (M).
19.7, 14.2. IR (CH2Cl2, cmꢀ1): 2212 (CÅ
N). MS (EI): 332 (Mꢂ1).
/
C), 2117 (CÅ
/
/
2.3.5. (S)-4-(4-(1-Methylhexyloxy)phenylethynyl)-2,6-
dimethylphenylisocyanide (4d)
2.3.10. (S)-4-(4-(1-
Methylheptyloxy)phenylethynyl)phenylisocyanide (4j)
1
Light yellow oil. Yield: 78%. H-NMR (CDCl3): d
1
7.42 (2H, d, Jꢁ
(2H, d, Jꢁ8.8 Hz, ArÁ
(6H, s, ArÁCH3), 1.73Á1.25 (11H, m, C4H8, CH3), 0.88
/
8.8 Hz, ArÁ
/
H), 7.24 (2H, s, ArÁ/H), 6.85
Light yellow solid. Yield: 74%. H-NMR (CDCl3): d
7.51 (2H, d, Jꢁ8.5 Hz, ArÁH), 7.44 (2H, d, Jꢁ8.8 Hz,
ArÁH), 7.31 (2H, d, Jꢁ8.5 Hz, ArÁH), 6.86 (2H, d,
Jꢁ8.8 Hz, ArÁ 1.24
/
/H), 4.37 (1H, m, CHMe2), 2.41
/
/
/
/
/
/
/
/
(3H, m, CH3). 13C-NMR (CDCl3): d 168.9, 158.9, 134.9,
133.2, 130.6, 128.4, 124.3, 115.7, 114.3, 91.6, 86.9, 74.0,
36.4, 31.8, 25.2, 22.6, 19.7, 18.8, 14.2. IR (CH2Cl2,
/
/
H), 4.39 (1H, m, CHMe2), 1.74Á
/
(13H, m, C5H10, CH3), 0.88 (3H, m, CH3). 13C-NMR
(CD2Cl2): d 165.4, 158.8, 133.2, 132.3, 126.4, 125.2,
115.7, 113.9, 92.6, 86.5, 73.9, 36.4, 31.8, 29.2, 25.5, 22.6,
19.7, 14.2. IR (CH2Cl2, cmꢀ1): 2212 (CÅ
N). MS (EI): 331 (M).
cmꢀ1): 2206 (CÅ
/
C), 2117 (CÅ/N). MS (EI): 345 (M).
/
C), 2117 (CÅ
/
2.3.6. (S)-4-(4-(1-Methylheptyloxy)phenylethynyl)-
2,6-dimethylphenylisocyanide (4f)
1
Light yellow oil. Yield: 77%. H-NMR (CDCl3): d
2.3.11. (S)-4-(4-(1-Methylhexyloxy)-2,6-
dimethylphenylethynyl)-2,6-dimethylphenylisocyanide
(4k)
1
Light yellow solid. Yield: 80%. H-NMR (CDCl3): d
7.42 (2H, d, Jꢁ
(2H, d, Jꢁ8.8 Hz, ArÁ
(6H, s, ArÁCH3), 1.73Á1.25 (13H, m, C5H10, CH3), 0.88
/
8.8 Hz, ArÁ
/
H), 7.24 (2H, s, ArÁ/H), 6.85
/
/H), 4.37 (1H, m, CHMe2), 2.41
/
/
(3H, m, CH3). 13C-NMR (CDCl3): d 168.9, 158.9, 134.9,
133.2, 130.6, 126.5, 124.3, 115.7, 114.3, 91.6, 86.9, 74.1,
36.4, 31.8, 29.3, 25.5, 22.6, 19.7, 18.9, 14.2. IR (CH2Cl2,
7.24 (2H, s, ArÁ
CHMe2), 2.41 (6H, s, ArÁ
/
H), 7.18 (2H, s, ArÁ
CH3), 2.25 (6H, s, ArÁ
1.18 (11H, m, C4H8, CH3), 0.89 (3H, m, CH3).
/
H), 4.08 (1H, m,
/
/CH3),
1.78Á
/
cmꢀ1): 2209 (CÅ
/
C), 2117 (CÅ/N). MS (EI): 359 (M).
13C-NMR (CDCl3): d 168.8, 155.5, 134.9, 132.3, 131.8,
130.7, 124.2, 117.0, 91.6, 87.1, 78.3, 36.9, 32.1, 25.1,
22.7, 19.7, 18.8, 17.2, 14.1. IR (CH2Cl2, cmꢀ1): 2206
2.3.7. (R)-4-(4-(1-
Methylpentyloxy)phenylethynyl)phenylisocyanide (4g)
1
Light yellow oil. Yield: 70%. H-NMR (CDCl3): d
(CÅ
/
C), 2117 (CÅ/N). MS (EI): 373 (M).
7.51 (2H, d, Jꢁ
ArÁH), 7.34 (2H, d, Jꢁ
Jꢁ8.8 Hz, ArÁH), 4.39 (1H, m, CHMe2), 1.77-1.26
/
8.5 Hz, ArÁ
/
H), 7.44 (2H, d, Jꢁ
/
8.9 Hz,
2.3.12. (R)-4-(4-(1-Methylheptyloxy)-2,6-
dimethylphenylethynyl)-2,6-dimethylphenylisocyanide
(4l)
/
/
8.5 Hz, ArÁ
/
H), 6.86 (2H, d,
/
/
(9H, m, C3H6, CH3), 0.91 (3H, m, CH3). 13C-NMR
(CD2Cl2): d 165.6, 158.9, 133.2, 132.3, 126.4, 125.3,
115.8, 114.1, 92.6, 86.5, 74.1, 36.1, 29.7, 22.7, 19.7, 14.0.
Yellow solid. Yield: 83%. H-NMR (CDCl3): d 7.24
1
(2H, s, ArÁ
CHMe2), 2.40 (6H, s, ArÁ
/
H), 7.18 (2H, s, ArÁ
CH3), 2.25 (6H, s, ArÁ
1.18 (13H, m, C5H10, CH3), 0.89 (3H, m,
/
H), 4.10 (1H, m,
/
/
IR (CH2Cl2, cmꢀ1): 2212 (CÅ
/
C), 2118 (CÅ/N). MS (EI):
CH3), 1.78Á
/
303 (M).
CH3). 13C-NMR (CDCl3): d 168.9, 155.5, 134.9, 132.3,
131.8, 130.7, 124.2, 117.0, 91.6, 87.1, 78.3, 37.1, 31.9,
29.5, 25.7, 22.6, 19.7, 18.8, 17.2, 14.1. IR (CH2Cl2,
2.3.8. (S)-4-(4-(1-
Methylhexyloxy)phenylethynyl)phenylisocyanide (4h)
1
Light yellow oil. Yield: 72%. H-NMR (CDCl3): d
cmꢀ1): 2208 (CÅ
/
C), 2119 (CÅ
/
N). MS (EI): 387 (M).
7.51 (2H, d, Jꢁ
ArÁH), 7.34 (2H, d, Jꢁ
Jꢁ8.8 Hz, ArÁ
/
8.6 Hz, ArÁ
/
H), 7.44 (2H, d, Jꢁ
H), 6.86 (2H, d,
1.25
/
8.9 Hz,
2.4. Synthesis of metal complexes 1
/
/
8.6 Hz, ArÁ
/
/
/
H), 4.39 (1H, M, CHMe2), 1.76Á
/
2.4.1. Complex 1e
(11H, m, C4H8, CH3), 0.89 (3H, m, CH3). 13C-NMR
(CD2Cl2): d 165.4, 158.9, 133.2, 132.3, 126.4, 125.3,
115.7, 114.0, 92.6, 86.5, 74.0, 36.3, 31.8, 25.1, 22.6, 19.7,
Under an atmosphere of nitrogen, PtI2 (143.8 mg,
0.32 mmol) is added to a stirred solution of 4e (230 mg,
0.64 mmol) in 15 ml CH2Cl2 [27]. After stirring for 6 h,
the yellow solution is filtered, and the solvent is removed
under vacuum. The residue is recrystallized from
14.0. IR (CH2Cl2, cmꢀ1): 2216 (CÅ
(EI): 317 (M).
/
C), 2125 (CÅ
/
N). MS

A. Mayr et al. / Journal of Organometallic Chemistry 684 (2003) 287Á
/299
293
dichloromethaneÁ
262 mg (70%). 1H-NMR (CDCl3): d 7.44 (2H, d, Jꢁ
Hz, ArÁH), 7.28 (2H, s, ArÁH), 6.86 (2H, d, Jꢁ8.8 Hz,
ArÁH), 4.38 (1H, m, CHMe2), 2.56 (6H, s, ArÁCH3),
1.74Á1.28 (13 H, m, C5H10, CH3), 0.88 (3H, m, CH3).
/
n-hexane to give a yellow solid. Yield:
(3H, m, CH3). IR (CH2Cl2, cmꢀ1): 2212 (CÅ
(CÅ
/
C), 2118
N). 13C-NMR (CDCl3): d 158.9, 136.8, 133.3, 130.9,
/8.8
/
/
/
/
126.1, 124.4, 115.8, 114.0, 93.0, 86.8, 74.0, 36.3, 31.8,
25.2, 22.6, 19.7, 18.9, 14.1. IR (CH2Cl2, cmꢀ1): 2212
/
/
/
(CÅ
/
C), 2191 (CÅ
/
N). MS (FAB) m/z: 1140 (Mꢂ1).
/
13C-NMR (CDCl3): d 158.9, 136.8, 133.3, 130.9, 126.1,
124.5, 115.8, 114.1, 93.0, 86.8, 74.1, 36.4, 31.8, 29.3,
25.5, 22.6, 19.7, 18.9, 14.2. IR (CH2Cl2, cmꢀ1): 2216
Anal. Calc. for C48H54I2N2O2Pt: C, 50.57; H, 4.74; N,
2.46. Found: C, 50.65; H, 4.52; N, 2.51.
(CÅ
/
C), 2189 (CÅ
/
N). MS (FAB) m/z: 1168 (Mꢂ
/
1).
2.4.6. Complex 1f
Yellow crystals. Yield: 80%. 1H-NMR (CDCl3): d
Anal. Calc. for C50H58I2N2O2Pt: C, 51.41; H, 4.97; N,
2.40. Found: C, 51.30; H, 5.05; N, 2.36%.
7.44 (2H, d, Jꢁ
(2H, d, Jꢁ8.8 Hz, ArÁ
(6H, s, ArÁCH3), 1.74Á
0.88 (3H, m, CH3). IR (CH2Cl2, cmꢀ1): 2212 (CÅ
2189 (CÅ
N). 13C-NMR (CDCl3): d 158.9, 136.8, 133.3,
/
8.8 Hz, ArÁ
H), 4.39 (1H, m, CHMe2), 2.56
1.29 (13 H, m, C5H10, CH3),
C),
/
H), 7.29 (2H, s, ArÁ
/
H), 6.86
/
/
2.4.2. Complex 1a
Yellow crystals. Yield: 81%. 1H-NMR (CDCl3): d
/
/
/
7.44 (2H, d, Jꢁ
(2H, d, Jꢁ8.8 Hz, ArÁ
(6H, s, ArÁCH3), 1.77-1.31 (9 H, m, C3H6, CH3), 0.88
(3H, m, CH3). IR (CH2Cl2, cmꢀ1): 2212 (CÅ
C), 2118
(CÅ
N). 13C-NMR (CDCl3): d 158.9, 136.8, 133.3, 130.9,
126.1, 115.7, 114.0, 92.8, 86.8, 73.7, 38.5, 29.7, 19.7,
18.9, 18.7, 14.0. IR (CH2Cl2, cmꢀ1): 2210 (CÅ
C), 2192
(CÅN). MS (FAB) m/z: 1083 (M). Anal. Calc. for
/
8.8 Hz, ArÁ
/
H), 7.29 (2H, s, ArÁ/H), 6.86
/
/
/H), 4.39 (1H, m, CHMe2), 2.56
130.9, 126.1, 124.4, 115.7, 114.0, 93.0, 86.8, 74.0, 36.4,
/
31.8, 29.3, 25.5, 22.6, 19.7, 18.9, 14.1. IR (CH2Cl2,
/
cmꢀ1): 2216 (CÅ
(Mꢂ
4.97; N, 2.40. Found: C, 51.67; H, 4.80; N, 2.46%.
/
C), 2189 (CÅ
/
N). MS (FAB) m/z: 1168
/
/
1). Anal. Calc. for C50H58I2N2O2Pt: C, 51.41; H,
/
/
2.4.7. Complex 1g
Yellow crystals. Yield:81%. 1HNMR (CDCl3): d 7.59
C44H46I2N2O2Pt: C 48.75; H, 4.25; N, 2.59. Found: C,
48.58; H, 4.14; N, 2.13.
(2H, d, Jꢁ
H), 7.46 (2H, d, Jꢁ
Hz, ArÁ
/
8.6 Hz, ArÁ
/
H), 7.51 (2H, d, Jꢁ
H), 6.87 (2H, d, Jꢁ
1.26 (9H, m,
/
8.6 Hz, ArÁ
/
/
8.7 Hz, ArÁ
/
/8.8
2.4.3. Complex 1b
Yellow crystals. Yield: 78%. 1H-NMR (CDCl3): d
/
H), 4.39 (1H, m, CHMe2), 1.78Á
/
C3H6, CH3), 0.91 (3H, m, CH3). 13C-NMR (CD2Cl2): d
159.1, 133.4, 132.5, 127.2, 126.8, 124.3, 115.8, 113.7,
94.1, 86.4, 74.0, 36.1, 27.7, 22.6, 19.7, 14.1. IR (CH2Cl2,
7.44 (2H, d, Jꢁ
(2H, d, Jꢁ8.8 Hz, ArÁ
(6H, s, ArÁCH3), 1.77Á
/
8.8 Hz, ArÁ
/
H), 7.29 (2H, s, ArÁH), 6.86
/
/
/
H), 4.39 (1H, m, CHMe2), 2.56
1.31 (9 H, m, C3H6, CH3), 0.88
/
/
cmꢀ1): 2214 (CÅ
(Mꢂ
3.98; N, 2.65. Found: C, 47.85; H, 3.96; N, 2.43.
/
C), 2194 (CÅ
/N). MS (FAB) m/z: 1056
(3H, m, CH3). IR (CH2Cl2, cmꢀ1): 2212 (CÅ
/
C), 2118
N). 13C-NMR (CDCl3): d 158.9, 136.8, 133.3, 130.9,
126.1, 124.4, 115.7, 114.0, 93.0, 86.8, 74.0, 36.4, 27.7,
22.7, 19.7, 18.9, 14.1. IR (CH2Cl2, cmꢀ1): 2216 (CÅ
C),
2189 (CÅN). MS (FAB) m/z: 1111 (M). Anal. Calc. for
/1) Anal. Calc. for C42H42I2N2O2Pt: C, 47.77; H,
(CÅ
/
/
2.4.8. Complex 1h
Yellow crystals. Yield: 74%. 1H-NMR (CDCl3): d
/
C46H50I2N2O2Pt: C, 49.69; H, 4.50; N, 2.52. Found: C,
49.26; H, 4.38; N, 2.19.
7.59 (2H, d, Jꢁ
ArÁH), 7.48 (2H, d, Jꢁ
Jꢁ8.8 Hz, ArÁ
/
8.8 Hz, ArÁ
/
H), 7.51 (2H, d, Jꢁ
H), 6.88 (2H, d,
1.25
/
8.7 Hz,
/
/
8.7 Hz, ArÁ
/
/
/
H), 4.39 (1H, m, CHMe2), 1.79Á
/
2.4.4. Complex 1c
Yellow crystals. Yield: 82%. 1H-NMR (CDCl3): d
(11H, m, C4H8, CH3), 0.89 (3H, m, CH3). 13C-NMR
(CD2Cl2): d 159.1, 133.4, 132.5, 127.2, 126.8, 124.3,
115.8, 113.7, 94.1, 86.4, 74.0, 36.3, 31.8, 25.2, 22.6, 19.7,
14.0. IR (CH2Cl2, cmꢀ1): 2214 (CÅ
7.44 (2H, d, Jꢁ
(2H, d, Jꢁ8.8 Hz, ArÁ
(6H, s, ArÁCH3), 1.77Á
/
8.8 Hz, ArÁ
/
H), 7.29 (2H, s, ArÁH), 6.86
/
/
/
H), 4.39 (1H, m, CHMe2), 2.56
1.31 (9 H, m, C3H6, CH3), 0.88
/
C), 2194 (CÅ/N). MS
/
/
(FAB) m/z: 1083 (M). Anal. Calc. for C44H46I2N2O2Pt:
C 48.75; H, 4.25; N, 2.59. Found: C, 48.77; H, 4.29; N,
2.60%.
(3H, m, CH3). IR (CH2Cl2, cmꢀ1): 2212 (CÅ
/
C), 2118
N). 13C-NMR (CDCl3): d 158.9, 136.8, 133.3, 130.9,
126.1, 124.4, 115.7, 114.0, 93.0, 86.8, 74.0, 36.4, 27.7,
22.7, 19.7, 18.9, 14.1. IR (CH2Cl2, cmꢀ1): 2216 (CÅ
C),
2189 (CÅN). MS (FAB) m/z: 1111 (M). Anal. Calc. for
(CÅ
/
/
2.4.9. Complex 1i
Yellow crystals. Yield: 78%. 1H-NMR (CDCl3): d
/
C46H50I2N2O2Pt: C, 49.69; H, 4.50; N, 2.52. Found: C,
49.52; H, 4.49; N, 2.18%.
7.59 (2H, d, Jꢁ
ArÁH), 7.46 (2H, d, Jꢁ
Jꢁ8.9 Hz, ArÁ
/
8.7 Hz, ArÁ
/
H), 7.51 (2H, d, Jꢁ
H), 6.88 (2H, d,
1.29
/
8.9 Hz,
/
/
8.7 Hz, ArÁ
/
/
/
H), 4.39 (1H, m, CHMe2), 1.76Á
/
2.4.5. Complex 1d
Yellow crystals. Yield: 82%. 1H-NMR (CDCl3): d
(13H, m, C5H10, CH3), 0.88 (3H, m, CH3). 13C-NMR
(CD2Cl2): d 159.1, 133.4, 132.5, 127.2, 126.8, 124.3,
115.8, 113.7, 94.1, 86.4, 73.9, 36.4, 31.8, 29.2, 25.5, 22.6,
7.44 (2H, d, Jꢁ
(2H, d, Jꢁ8.8 Hz, ArÁ
(6H, s, ArÁCH3), 1.79Á1.29 (11 H, m, C4H8, CH3), 0.89
/
8.8 Hz, ArÁ
/
H), 7.29 (2H, s, ArÁH), 6.86
/
/
/
H), 4.39 (1H, m, CHMe2), 2.56
19.7, 14.1. IR (CH2Cl2, cmꢀ1): 2216 (CÅ
/
C), 2194 (CÅ
/
/
/
N). MS (FAB) m/z: 1111 (M). Anal. Calc. for

294
A. Mayr et al. / Journal of Organometallic Chemistry 684 (2003) 287Á299
/
C46H50I2N2O2Pt: C, 49.68; H, 4.50; N, 2.52. Found: C,
49.38; H, 4.45; N, 2.47%.
DENZO [28]. The X-ray radiation from all generators was
graphite-monochromatized MoÁKa X-ray radiation
0.71073 A). Empirical absorption corrections based
/
˚
(lꢁ
/
2.4.10. Complex 1j
Yellow crystals. Yield: 72%. 1H-NMR (CDCl3): d
on the c-scan of five strong reflections were applied to
the data of 1a. The structure determinations were done
using the MSC crystal structure analysis package
TEXSAN [29] and the full-matrix least squares refine-
7.59 (2H, d, Jꢁ
ArÁH), 7.48 (2H, d, Jꢁ
Jꢁ8.9 Hz, ArÁ
/
8.7 Hz, ArÁ
/
H), 7.51 (2H, d, Jꢁ
H), 6.88 (2H, d,
1.25
/
8.7 Hz,
/
/
8.7 Hz, ArÁ
/
/
/
H), 4.39 (1H, m, CHMe2), 1.76Á
/
ments were on F using reflections with I ꢀ3 or 2sI.
/
(13H, m, C5H10, CH3), 0.88 (3H, m, CH3). 13C-NMR
(CD2Cl2): d 159.1, 133.4, 132.5, 127.2, 126.8, 124.3,
115.8, 113.7, 94.1, 86.4, 74.0, 36.4, 31.8, 29.2, 25.5, 22.6,
Hydrogen atoms at calculated positions with thermal
parameters equal to 1.3 times that of the attached C
atoms were included in the calculations, but not refined.
19.7, 14.1. IR (CH2Cl2, cmꢀ1): 2216 (CÅ
/
C), 2194 (CÅ
/
N). MS (FAB) m/z: 1111 (M). Anal. Calc. for
C46H50I2N2O2Pt: C, 49.68; H, 4.50; N, 2.52. Found: C,
49.77; H, 4.99; N, 2.21%.
3. Results and discussion
3.1. Synthesis and spectroscopic characterization of the
isocyanide metal complexes
2.4.11. Complex 1k
Yellow crystals. Yield: 81%. 1H-NMR (CDCl3): d
7.27 (2H, s, ArÁ
CHMe2), 2.55 (6H, s, ArÁ
/
H), 7.19 (2H, s, ArÁ
CH3), 2.26 (6H, s, ArÁ
1.18 (11H, m, C4H8, CH3), 0.90 (3H, m, CH3).
/
H), 4.11 (1H, m,
The trans-diiodo-bis(isocyanide)platinum(II) com-
/
/CH3),
plexes 1aÁ
reaction of two equivalents of the corresponding iso-
cyanides 4aÁl with platinum(II) iodide in CH2Cl2. The
isocyanides 4aÁl were obtained from the anilines 2aÁ
via the formamide derivatives 3aÁl, following estab-
lished procedures [25,26].
/l were prepared as shown in Scheme 1 by
1.78Á
/
13C-NMR (CDCl3): 155.7, 136.8, 132.3, 131.8, 131.0,
126.0, 124.5, 116.8, 92.9, 87.0, 78.3, 37.0, 32.0, 25.4,
22.5, 19.8, 18.9, 17.2, 14.1. IR (CH2Cl2, cmꢀ1): 2210
/
/
/l
/
(CÅ
/
C), 2189 (CÅ
/N). Anal. Calc. for C52H62I2N2O2Pt:
C, 52.21; H, 5.19; N, 2.34. Found: C, 51.84; H, 5.14; N,
2.33.%
The ethynyl and isocyanide groups of the free ligands
give rise to characteristic IR absorptions in the ranges of
2200Á
coordination of the isocyanides to platinum(II), the CÅ
C stretching frequencies remain largely unchanged while
the NÅC stretching frequencies increase by about 70
wavenumbers to 2189Á
2194 cmꢀ1 [27]. For the free
isocyanide groups, 13C-NMR signals were observed at d
165Á170 [30]. The corresponding resonances of the
/
2220 and 2115Á
2125 cmꢀ1, respectively. Upon
/
2.4.12. Complex 1l
Yellow solid. Yield: 93%. H-NMR (CDCl3): d 7.27
/
1
(2H, s, ArÁ
CHMe2), 2.55 (6H, s, ArÁ
/
H), 7.19 (2H, s, ArÁ
CH3), 2.26 (6H, s, ArÁ
1.15 (13H, m, C5H10, CH3), 0.89 (3H, m,
/H), 4.09 (1H, m,
/
/
/
/
CH3), 1.78Á
/
CH3). 13C-NMR (CDCl3): 155.7, 136.8, 132.3, 131.8,
131.0, 126.1, 124.5, 116.8, 92.9, 87.0, 78.3, 37.0, 31.8,
29.5, 25.6, 22.6, 19.8, 18.9, 17.2, 14.1. IR (CH2Cl2,
/
coordinated isocyanide carbon atoms could not be
detected due to their low intensity. The 13C-NMR
signals of the ethynyl groups occur between d 85 and
95 and are little affected by coordination of the
isocyanide groups to the metal center [31].
cmꢀ1): 2210 (CÅ
/
C), 2189 (CÅ/N). Anal. Calc. for
C54H66I2N2O2Pt: C, 52.98; H, 5.39; N, 2.29. Found: C,
52.82; H, 5.46; N, 2.01%.
2.5. X-ray crystal structure analyses of complexes 1a, 1d
and 1k
3.2. Crystal structures of complexes 1a, 1d and 1k
The crystal structures of complexes 1a, 1d and 1k have
been determined by X-ray crystallography. The crystal
parameters and information on data collection and
refinement are summarized in Table 1. Selected bond
lengths and bond angles are listed in Table 2, and the
molecular structures are shown in Fig. 1. All three
structures confirm the trans arrangement of the isocy-
anide ligands, giving rise to the overall linear shapes of
the molecules. The individual bond distances and bond
angles are unexceptional. The length of the unsaturated
core, as measured by the distance between the two
oxygen atoms in the 4-positions of the outer phenyl
The crystal parameters of compounds 1a, 1d, and 1k
and information on data collection and refinement are
summarized in Table 1. The diffraction data for
compounds 1a were collected on a Rigaku AFC7R
four-circle diffractometer using X-ray radiation from a
Rigaku RU-200 rotating anode generator at 50 kV and
160 mA and processed by the MSC/Rigaku diffract-
ometer control software. The diffraction data for
complex 1d were collected on a Siemens SMART
CCD diffractometer. The diffraction data for complex
1k were collected on a MAR imaging plate detector
system using X-ray radiation from an MAR generator
(sealed tube 50 kV and 50 mA), and processed by
˚
rings, is about 30.7 A, slightly longer than in complexes
I. A common feature of the three solid state structures is

A. Mayr et al. / Journal of Organometallic Chemistry 684 (2003) 287Á
/299
295
the arrangement of the flat linear molecules in slanted
stacks, whereby neighboring molecules are shifted
relative to each other to such an extent that each bulky
platinum center is flanked on either side by a slender
ethynylene group from the neighboring molecules. This
situation is illustrated for 1k in Fig. 2. Since there are no
unusually short intermolecular distances, this arrange-
ment is apparently a consequence of the crystal packing
forces. Complex 1k differs from complexes 1a and 1d by
the presence of two methyl substituents on the outer
phenyl rings. The increased steric bulk at the ends of the
rigid core creates extra room to fill for the adjacent
flexible alkoxy chains, which do so by adopting a non-
zigzag conformation. In all other solid-state structures
of mesogenic isocyanide metal complexes determined so
far only alkoxy chains with fully stretched-out confor-
mations have been found. While linear zigzag conforma-
tions of alkoxy chains are the norm in crystalline
calorimetry (DSC) and polarized optical microscopy.
The phase transition temperatures and the associated
enthalpies are listed in Table 3. Complexes 1aÁj exhibit
/
an oil streak texture, indicating the presence of a chiral
nematic (N*) phase [39]. Complexes 1k and 1l display a
smectic A (SmA) phase characterized by a fan-shaped
texture [40].
A plot of the phase transition temperatures of
complexes 1aÁl versus the length of the alkyl chains is
/
shown in Fig. 3. All complexes have terminal 1-methyl-
alkoxy chains. They are divided into three groups. In
complexes 1aÁ/1f, the isocyanophenyl groups bear two
methyl groups, as in complexes I. In complexes 1gÁ
/j,
these methyl substituents have been removed, and in
complexes 1k and 1l, two additional methyl groups have
been introduced on the outer phenyl rings. Compared to
complexes 1aÁ
/
f, complexes 1gÁj have lower phase
/
transition temperatures and a significantly narrower
range for the liquid crystal phase. The broadness of the
mesogens [32Á35], twists in the conformations never-
/
theless appear to be induced readily by particular
structural features or general crystal packing forces
liquid crystal phase of complexes 1aÁf supports our
/
previous conclusion that the lateral methyl substituents
adjacent to the metal center improve the liquid crystal
properties. Complexes 1k and 1l have higher melting
points and slightly lower clearing temperatures than
complexes 1d and 1e,f, which have alkoxy chains of the
same length. Apparently, the additional methyl substi-
tuents at the periphery of the rigid core stabilize the
[36Á38].
/
3.3. Liquid crystal properties
The thermal properties of complexes 1aÁ
studied by a combination of differential scanning
/l were

296
A. Mayr et al. / Journal of Organometallic Chemistry 684 (2003) 287Á299
/
Table 1
Crystal and data collection parameters for complexes 1a, 1d and 1k
1a
1d
1k
Formula
C
44H46I2N2O2Pt
C48H54I2N2O2Pt
1139.8
C52H62I2N2O2Pt
1195.97
Monoclinic
Formula weight
Crystal system
Space group
1083.76
Triclinic
¯
P1 (no. 2)
Monoclinic
C2
P21/n (no. 14)
Unit cell dimensions
˚
a (A)
˚
8.866(1)
10.651(2)
12.792(2)
71.28(1)
69.81(1)
79.74(1)
1070.6(3)
1
20.851(4)
11.517(2)
10.798(2)
10.578(2)
20.381(3)
12.154(2)
b (A)
˚
c (A)
a (8)
b (8)
116.16(3)
97.12(2)
g (8)
3
V (A )
˚
2327.3(25)
2
296
2600.1(7)
2
301
Z
T (K)
Crystal color
Crystal dimensions (mm3)
301
Yellow
Yellow
Yellow
0.35ꢃ/0.1ꢃ
/
0.1
0.15ꢃ
/
0.20ꢃ
/
0.35
0.30ꢃ
/
0.07ꢃ0.07
/
Dcalc (g cmꢀ3
m cmꢀ1()
Scan mode
)
1.681
47.42
1.626
4.378
v
1.527
39.13
v Á
48
3355
/2u
Á/
50.9
4029
2umax (8)
Unique reflections
50.0
3258
Reflections used in LS refinement
No. of variables
2346 (I ꢀ
232
0.042 a
0.066 b
0.05
/
3s(I))
2565 (F ꢀ
/
4.0s(F))
2541 (I ꢀ
268
0.062 a
0.092 b
0.05
/
3s(I))
249
0.065
0.086
R
Rw
(D/s)max
Goodness-of-fit
1.84
1.58
2.85
ꢀ3
˚
Dr (e A
)
ꢀ
/
0.65/1.03
ꢀ
/
1.09/1.98
ꢀ/1.07/0.97
a
Rꢁ
Rwꢁ
/
SjjFojꢀ
/
jFcjj/SjFoj.
/
b
/
[S w(jFojꢀ
jFcj)2/S wF2o]1/2, where wꢁ
/
F2o/[s2(I)ꢂ(pF2o)2].
/
Table 2
Selected bond lengths (A) and bond angles (8) for complex 1a, 1d and 1k
˚
1a
1d
1k
Bond lengths
Pt(1)Á
N(1)ÁC(1)
C(5)Á
C(9)Á
/
I(1)
2.6017(7)
1.16(1)
1.41(1)
1.40(1)
1.947(9)
1.39(1)
1.21(1)
Pt(1)Á
Pt(1)Á
N(1)Á
C(10)Á
Pt(1)ÁI(2)
N(1)ÁC(1)
C(5)ÁC(10)
C(11)ÁC(12)
/
I(1)
C(1)
C(2)
2.596(3)
1.81(2)
1.43(2)
1.23(3)
2.606(4)
1.25(3)
1.47(3)
1.47(3)
Pt(1)Á
N(1)Á
C(5)Á
C(9)Á
/
I(1)
2.597(1)
1.19(1)
1.44(1)
1.42(1)
1.93(1)
1.38(1)
1.19(1)
/
/
/C(1)
/
C(8)
/
/
C(8)
/
C(10)
/
C(11)
/
C(10)
Pt(1)Á
N(1)ÁC(2)
C(8)ÁC(9)
/C(1)
/
Pt(1)Á
N(1)ÁC(2)
C(8)ÁC(9)
/
C(1)
/
/
/
/
/
/
/
Bond angles
I(1)ÁPt(1)ÁC(1)
C(1)ÁN(1)ÁC(2)
C(8)ÁC(9)ÁC(10)
Pt(1)ÁC(1)ÁN(1)
C(5)ÁC(8)ÁC(9)
C(13)ÁO(1)ÁC(16)
/
/
91.1(3)
178.1(9)
173(1)
I(1)Á
I(2)Á
C(1)Á
C(10)Á
I(1)ÁPt(1)Á
Pt(1)ÁC(1)Á
C(5)ÁC(10)Á
/
Pt(1)Á
/
I(2)
180.0(1)
I(1)Á
C(1)Á
C(8)Á
Pt(1)Á
C(5)ÁC(8)Á
/
Pt(1)Á
N(1)Á
C(9)ÁC(10)
C(1)ÁN(1)
C(9)
/
C(1)
91.3(4)
/
/
/
Pt(1)Á
/
C(1)
90(1)
177(3)
177(3)
90(1)
/
/C(2)
178(1)
174(1)
174(1)
172(1)
/
/
/
N(1)Á
C(11)Á
C(1)
N(1)
C(11)
/C(2)
/
/
/
/
178.5(8)
176(1)
/
/C(12)
/
/
/
/
/
/
/
/
/
/
129(1)
/
/
176(3)
173(4)
/
/

A. Mayr et al. / Journal of Organometallic Chemistry 684 (2003) 287Á
/299
297
crystal phase due to increased intermolecular interac-
tions between the enlarged rigid cores, but they do not
stabilize the mesophase. As the results of the crystal
structure determination of complex 1k suggest, these
methyl groups create an abrupt transition between a
wide rigid core and a narrow flexible chain, thereby
creating space for the alkoxy chains to adopt non-
stretched-out conformations. Thus, the additional meth-
yl groups on the peripheral phenyl rings of the
isocyanide ligands do not enhance the liquid crystal
properties. We also observed that complexes 1k and 1l
display a higher viscosity than complexes 1aÁ
Complexes I with nꢁ5, 6 and 8 exhibit an N phase
with CÁN transition temperatures varying from 244 to
206 8C and NÁI transition temperatures ranging from
318 to 295 8C. The liquid crystal phase of complexes 1aÁ
f (nꢁ4Á7) is narrower, but overlaps with the lower end
/
j.
/
/
/
/
/
/
of that range. Considering the difference in the alkyl
chains, this result shows that the replacement of the
imino unit in complexes I by an ethynylene bridge does
not dramatically alter the liquid crystal properties and
suggests that a comparison of the thermal behavior of
complexes I and complexes 1aÁ
complexes I with nꢁ5Á8, complexes 1aÁ
nematic phase. In the series of complexes I, an SmC
phase emerges at an alkyl chain length of nꢁ10. We
conclude that the alkyl chains in complexes 1aÁf are too
/
f is meaningful. Like
/
/
/f do exhibit a
/
/
short for a smectic phase to be observed, but would
expect a SmC* phase to emerge in this series at longer
chain lengths. In contrast, among the isocyanide com-
plexes reported by Serrano to exhibit a SmC* phase was
also the related compound PdI2(CNC6H4-4-(CO2C6H4-
4-O-(R)-CHMeC5H11) with an alkyl chain length of nꢁ
6 [17].
For complexes 1a, 1c, 1d and 1f, the reflection spectra
/
of films with the planar texture were measured [41]. The
results are summarized in Table 4. The reflection
spectrum of 1f at 190 8C is shown in Fig. 4 as a
representative example. For compound 1d, the pitch
[42] ranges from 394 to 352 nm in the temperature range
of 175Á
/
220 8C, for compound 1f from 462 to 365 nm in
the temperature range of 170Á
/
210 8C.
3.4. Conclusions
This study confirms our earlier suggestion that lateral
methyl substituents on the isocyanophenyl groups in
trans-diiodo-bis(isocyanide)palladium(II) and platinu-
m(II) complexes exert a beneficial influence on the
liquid crystal properties. Additional methyl substituents
on arene groups that are further removed from the
bulky metal center appear to have a negative effect.
Fig. 1. (a) ORTEP drawing of compound 1a. The thermal ellipsoids are
shown at the 40% probability level. (b) Molecular structure of
compound 1d. (c) ORTEP drawing of compound 1k. The thermal
ellipsoids are shown at the 40% probability level.
Complexes 1aÁ/1f exhibit an N* phase with pitches
ranging from 350 to 400 nm.

298
A. Mayr et al. / Journal of Organometallic Chemistry 684 (2003) 287Á299
/
Fig. 2. Drawing of two neighboring molecules in the crystal structure of 1k.
Table 3
Mesomorphic properties of complexes 1aÁl
/
Compound
Transition
N*
T (8C)
DH (kJ molꢀ1
)
1a
CÁ
N*Á
CÁN*
N*Á
CÁN*
N*Á
CÁN*
N*Á
IÁN*
N*Á
CÁN*
N*Á
IÁN*
N*Á
CÁN*
N*Á
IÁN*
N*Á
CÁN*
N*Á
IÁN*
N*Á
CÁN*
N*Á
IÁN*
N*Á
CÁN*
N*Á
IÁN*
N*Á
CÁN*
N*Á
IÁN*
N*Á
CÁSA
SA
IÁSA
SA
CÁ
SA
IÁSA
SA
/
249
268 (dec.)
218
29.6
/
I
1b
1c
1d
/
31.0
28.2
26.7
/
I
254 (dec.)
217
/
/
I
255 (dec.)
169
/
/
I
229
220
0.9
a
/
a
/
C
161
1e
1f
1g
1h
1i
/
152
214
25.5
1.0
/
I
a
/
208
a
/
C
144
Fig. 3. Plot of phase transition temperatures of complexes 1aÁl versus
/
/
151
26.6
number of carbon atoms in the longest alkoxy chains. Only the data
obtained from heating the samples are included.
/
I
215
207
1.1
a
/
a
/
C
141
/
141
159
25.8
a
Table 4
Reflection data and pitches for the planar texture of selected complexes
/
I
a
/
145
Complex
T (8C)
l (nm)
Po (nm) a
/
C
131
24.2
/
137
145
23.2
a
1a
1c
1d
252
228
175
180
190
200
210
220
170
180
190
200
210
730
752
630
622
604
589
570
563
739
693
649
615
584
457
470
394
389
378
368
357
352
462
433
406
385
365
/
I
a
/
130
/
C
127
24.4
/
129
135
28.1
a
/
I
a
/
121
/
C
114
20.5
1j
/
130
136
27.1
a
1f
/
I
a
/
121
/
C
113
19.1
1k
1l
/
195
227
39.2
a
Á/
I
a
/
210
a
lꢁ
/
n ꢃPo; l is the wavelength of the center of the reflectance
/
¯
peak; n is the average refractive index of the liquid crystal sample (1.6);
Á/
C
181
180
21.5
36.2
¯
Po is the pitch.
/SA
Á/
I
200
198
1.1
a
/
Á/
C
168
12.6
a
Not detected by DSC.
pounds 1a, 1d, and 1k, respectively. Copies of this
information may be obtained free of charge from The
Director, CCDC, 12 Union Road, Cambridge CB2 1EZ,
4. Supplementary material
Crystallographic data for the structural analysis have
been deposited with the Cambridge Crystallographic
UK (Fax: ꢂ44-1223-336033; e-mail: deposit@ccdc.ca-
/
Data Centre, CCDC nos. 205900Á205902 for com-
/
m.ac.uk or www: http://www.ccdc.cam.ac.uk).

A. Mayr et al. / Journal of Organometallic Chemistry 684 (2003) 287Á
/299
299
[13] M. Benouazzane, S. Coco, P. Espinet, J. Barbera´, J. Mater. Chem.
11 (2001) 1740.
[14] M. Benouazzane, S. Coco, P. Espinet, J.M. Mart´ın-Alvarez, J.
Barbera´, J. Mater. Chem. 12 (2002) 691.
[15] R. Bayo´n, S. Coco, P. Espinet, Chem. Mater. 14 (2002) 3515.
[16] M. Benouazzane, S. Coco, P. Espinet, Inorg. Chem. 41 (2002)
754.
[17] A. Omenat, J.-L. Serrano, T. Sierra, D.B. Amabilino, M.
Minguet, E. Ramos, J. Veciana, J. Mater. Chem. 9 (1999) 2301.
[18] (a) S. Wang, A. Mayr, K.-K. Cheung, J. Mater. Chem. 8 (1998)
1561;
(b) P.R.P. Tuffin, K.J. Toyne, J.W. Goodby, J. Mater. Chem. 6
(1996) 1271.
[19] Y. Miuea, H. Oka, M. Momoli, Synthesis (1995) 1419.
[20] K.J. Edgar, S.N. Falling, J. Org. Chem. 55 (1990) 5287.
[21] K.-S. Jeong, Y.L. Cho, S.Y. Chang, T.-Y. Park, J.U. Song, J.
Org. Chem. 64 (1999) 9459.
[22] S. Takahashi, Y. Kuroyama, K. Sonogashira, N. Hagihara,
Synthesis (1980) 627.
[23] O. Mitsunobu, Synthesis (1981) 1.
Fig. 4. Reflection spectrum of complex 1f at 190 8C.
[24] O. Lavastre, L. Olliver, P.H. Dixneuf, S. Sibadhit, Tetrahedron 52
(1996) 5495.
Acknowledgements
[25] C.W. Huffmann, J. Org. Chem. 23 (1958) 727.
[26] H. Eckert, B. Forster, Angew. Chem. 99 (1987) 922; Angew.
Chem. Int. Ed. Engl. 26 (1987) 894.
Support for this work by the Committee on Con-
ference and Research Grants of The University of Hong
Kong and by the Hong Kong Research Grants Council
is gratefully acknowledged. We would like to thank
Prof. D.-K. Yang and Dr. F. Zhang for assistance with
the reflectance spectroscopy measurements.
[27] L. Malatesta, F. Bonati, Isocyanide Complexes of Transition
Metals, Wiley, New York, 1969.
[28] DENZO, in: The HKL Manual*/A description of the programs
DENZO
,
XDISPLAYF and SCALEPACK, written by D. Gewirth, with
the cooperation of the program authors Z. Otwinowski, W.
Minor, 1995.
[29] TEXSAN: Crystal Structure Analysis Package, Molecular Structure
Corporation, 1985 and 1992.
References
[30] K.Y. Lau, A. Mayr, K.-K. Cheung, Inorg. Chim. Acta 285 (1999)
223.
[1] T. Kaharu, S. Takahashi, Chem. Lett. (1992) 1515.
[2] T. Kaharu R. Ishii, S. Takahashi, J. Chem. Soc. Chem. Commun.
(1994) 1349.
[31] Z.-l. Lu, A. Mayr, K.-K. Cheung, Inorg. Chim. Acta 284 (1999)
205.
[32] D.W. Bruce, in: D.W. Bruce, D. O’Hare (Eds.), Inorganic
Materials, Wiley, Chichester, UK, 1992.
[3] T. Kaharu, T. Tanaka, M. Sawada, S. Takahashi, J. Mater.
Chem. 4 (1994) 859.
[33] P. Espinet, M.A. Esteruelas, L.A. Oro, J.L. Serrano, E. Sola,
Coord. Chem. Rev. 117 (1992) 215.
[4] T. Kaharu, R. Ishii, T. Adachi, T. Yoshida, S. Takahashi, J.
Mater. Chem. 5 (1995) 687.
[34] S.A. Hudson, P. Maitlis, Chem. Rev. 93 (1993) 861.
[35] J.-L. Serrano (Ed.), Metallomesogens, VCH, Weinheim, Ger-
many, 1996.
[5] M. Benouazzane, S. Coco, P. Espinet, J.M. Martin-Alvarez, J.
Mater. Chem. 5 (1995) 441.
[6] S. Coco, P. Espinet, S. Flanagan, J.M. Martin-Alvarez, New J.
Chem. 19 (1995) 959.
[36] K. Hori, M. Takamatsu, Bull. Chem. Soc. Jpn. 62 (1989) 1751.
[37] H. Iki, K. Hori, Bull. Chem. Soc. Jpn. 68 (1995) 1281.
[38] I.H. Ibrahim, H. Paulus, M. Mokhles, W. Haase, Mol. Cryst. Liq.
Cryst. 258 (1995) 185.
[7] P. Alejos, S. Coco, P. Espinet, New J. Chem. 19 (1995) 799.
[8] S. Coco, P. Espinet, J.M. Martin-Alvarez, A.-M. Levelut, J.
Mater. Chem. 7 (1997) 19.
[39] D. Demus, L. Richter, Textures of Liquid Crystals, Verlag
Chemie, Weinheim, 1978.
[9] R. Bayon, S. Coco, P. Espinet, C. Fernandez-Mayordomo, J.M.
Martin-Alvarez, Inorg. Chem. 36 (1997) 2329.
[10] S. Coco, F. D´ıez-Expo´sito, P. Espinet, C. Ferna´ndez-Mayor-
[40] G.W. Gray, J.W.G. Goodby, Smectic Liquid Crystals, Textures
and Structures, Leonhard Hill, Glasgow, 1984.
[41] J.L. Fergason, N.N. Goldberg, R.J. Nadalin, Mol. Crystals 1
(1966) 309.
´
domo, J.M. Mart´ın-Alvarez, A.M. Levelut, Chem. Mater. 10
(1998) 3666.
[11] M. Benouazzane, S. Coco, P. Espinet, J.M. Mart´ın-Alvarez, J.
´
[42] D.-K. Yang, X.-Y. Huang, Y.-M. Zhu, Annu. Rev. Mater. Sci. 27
(1997) 117.
Mater. Chem. 9 (1999) 2327.
[12] S. Coco, P. Espinet, E. Marcos, J. Mater. Chem. 10 (2000) 1297.