Syntheses and mesomorphic properties of gold(I)-carbene complexes

Article abstract of DOI:10.1021/om9606202

The liquid-crystalline gold(I)-carbene complexes ClAu=C(YC_mH_2m+1)(NHC₆H₄CO ₂C₆H₄-OC_nH_2n+1), Y = O and NH, have been prepared by reactions of gold(I)-isonitrile complexes [ClAU{CNC₆H₄CO₂C₆H ₄OC_nH_2n+1}] with alcohols and amines, respectively. The gold(I)-(alkoxy)(amino)carbene complexes show stable enantiotropic smectic A phases over the range of around 15 °C. The partial double-bond character of the C-N bond in the carbene complex gives rise to two geometrical isomers (E:Z = ca. 3:1). Their molecular structures were spectroscopically characterized, and the E-isomer was confirmed by an X-ray structural analysis. The phase behaviors of E- and Z-isomers which were isolated by repeated recrystallization from CHCl₃/Et₂O or CH₂Cl₂/C₆H₁₄ were examined. In the gold(I)-diaminocarbene complexes, a novel dinuclear gold-carbene complex, [ClAu{C(NHC₆H₄-CO₂C₆H ₄OC_nH_2n+1)}](NCH₃C_mH _2mNCH₃)[ClAu{C(NHC₆H₄CO ₂C₆H₄OC_nH_2n+1)}], was synthesized by the reaction with a secondary diamine. This dinuclear complex generated a smectic mesophase although it decomposed at temperatures below its clearing temperature.

Full text of DOI:10.1021/om9606202

20
Organometallics 1997, 16, 20-26
Syn th eses a n d Mesom or p h ic P r op er ties of
Gold (I)-Ca r ben e Com p lexes
Shi-Wei Zhang, Rie Ishii, and Shigetoshi Takahashi*
The Institute of Scientific and Industrial Research, Osaka University, Mihogaoka,
Ibaraki, Osaka 567, J apan
Received J uly 26, 1996X
The liquid-crystalline gold(I)-carbene complexes ClAudC(YCmH2m+1)(NHC6H4CO2C6H4-
OCnH2n+1), Y ) O and NH, have been prepared by reactions of gold(I)-isonitrile complexes
[ClAu{CNC6H4CO2C6H4OCnH2n+1}] with alcohols and amines, respectively. The gold(I)-
(alkoxy)(amino)carbene complexes show stable enantiotropic smectic A phases over the range
of around 15 °C. The partial double-bond character of the C-N bond in the carbene complex
gives rise to two geometrical isomers (E:Z ) ca. 3:1). Their molecular structures were
spectroscopically characterized, and the E-isomer was confirmed by an X-ray structural
analysis. The phase behaviors of E- and Z-isomers which were isolated by repeated
recrystallization from CHCl3/Et2O or CH2Cl2/C6H14 were examined. In the gold(I)-
diaminocarbene complexes, a novel dinuclear gold-carbene complex, [ClAu{C(NHC6H4-
CO2C6H4OCnH2n+1)}](NCH3CmH2mNCH3)[ClAu{C(NHC6H4CO2C6H4OCnH2n+1)}], was syn-
thesized by the reaction with a secondary diamine. This dinuclear complex generated a
smectic mesophase although it decomposed at temperatures below its clearing temperature.
In tr od u ction
new families of organometallic liquid crystals including
isonitrile complexes of platinum4 and gold.5 In contrast
to platinum-isonitrile complexes which display stable
mesomorphic properties over a high and wide temper-
ature range without any decomposition, most gold-
isonitrile complexes have suffered from considerable
decomposition due to high phase-transition tempera-
tures caused by strong intermolecular interactions.6
In our preliminary report,7 an effort was made to
decrease the transition temperatures of the gold-
isonitrile complexes by synthesizing liquid-crystalline
transition metal-carbene complexes by the nucleophilic
addition of alcohols to gold-isonitrile complexes (see
Scheme 1). The gold-carbenes exhibited exclusively
smectic phases with lower clearing temperatures than
the corresponding gold-isonitrile complexes due to the
introduction of lateral alkyl chains which weaken
intermolecular interaction. We now report the detailed
synthesis, complete characterization, and mesomorphic
properties of gold(I)-(alkoxy)(amino)carbene complexes.
This paper also reports the preparation of gold(I)-
diaminocarbene complexes by the nucleophilic reaction
of gold(I)-isonitrile complexes with amines. Addition-
Transition metal-carbene complexes have attracted
much attention as useful reagents, as effective catalysts,
and as molecules displaying unique bonding. Their
chemistry has been widely developed for application in
the fields of both catalytic reactions and stoichiometric
organic synthesis over the last three decades.1 How-
ever, little attention has been paid to the carbene
complexes from the viewpoint of material science,
though the complexes have expectantly novel physical
properties based on the direct metal-carbon double
bond.
In contrast, liquid crystals incorporating transition
metals, so-called metallomesogens, have attracted much
more interest due to the perceived advantages of com-
bining the properties of liquid-crystal systems with
those of transition metals. A large number of studies
on metallomesogens have been performed in the last 20
years, and the area has been well reviewed recently.2
Organometallic liquid crystals which contain a direct
metal-carbon bond have received much less attention,
and their study has been limited due to their thermal
and chemical instability. In an attempt to remedy this,
we had previously developed liquid-crystalline platinum-
alkynyls stabilized by trialkylphosphine ligands3 and
(3) Kaharu, T.; Matsubara, H.; Takahashi, S. J . Mater. Chem. 1992,
2, 43; Mol. Cryst. Liq. Cryst. 1992, 220, 191.
(4) Kaharu, T.; Takahashi, S. Chem. Lett. 1992, 1515. Kaharu, T.;
Tanaka, T.; Sawada, M.; Takahashi, S. J . Mater. Chem. 1994, 4, 859.
(5) Kaharu, T.; Ishii, R.; Takahashi, S. J . Chem. Soc., Chem.
Commun. 1994, 1349. Kaharu, T.; Ishii, R.; Adachi, T.; Yoshida, T.;
Takahashi, S. J . Mater. Chem. 1995, 5, 687.
(6) (a) Adams, H.; Albeniz, A. C.; Bailey, N. A.; Bruce, D. W.;
Cherodian, A. S.; Dhillon, R.; Dummur, D. A.; Espinet, P.; Feijoo, J .
L.; Lalimde, E.; Maitlis, P. M.; Richardson, P. M.; Urgan, G. J . Mater.
Chem. 1991, 1, 843. (b) Bruce, D. W.; Lalimde, E.; Styring, P.; Maitlis,
P. M. J . Chem. Soc., Chem. Commun. 1986, 581. (c) Pathaneni, S. S.;
Desiraju, G. R. J . Chem. Soc., Dalton Trans. 1993, 319. (d) Irwin, M.
J .; J ia, G.; Payne, N. C.; Puddephatt, R. J . Organometallics 1996, 15,
51.
X Abstract published in Advance ACS Abstracts, December 1, 1996.
(1) (a) Dotz, K. H. Angew. Chem. 1984, 96, 573; Angew. Chem., Int.
Ed. Engl. 1984, 23, 587. (b) Dotz, K. H.; Fischer, H.; Hofmann, P.;
Kreissl, F. R.; Scchubert, U.; Weiss, K. Transition Metal Carbene
Complexes; Verlag Chemie: Weinheim, Germany, 1993. (c) Wulff, W.
D. Adv. Met.-Org. Chem. 1989, 1, 209. (d) Brown, F. J . Prog. Inorg.
Chem. 1980, 27, 1.
(2) (a) Giroud-Godquim, A.-M.; Maitlis, P. M. Angew. Chem., Int.
Ed. Engl. 1991, 30, 375. (b) Espinet, P.; Esteruelas, M. A.; Oro, A.;
Serrano, J . L.; Sola, E. Coord. Chem. Rev. 1992, 117, 215. (c) Hudson,
S. A.; Maitlis, P. M. Chem. Rev. 1993, 93, 861. (d) Bruce, D. W. J .
Chem. Soc., Dalton Trans. 1993, 2983. (e) Polishchuk, A. P.; Timofeeva,
T. V. Russ. Chem. Rev. 1993, 62, 291.
(7) Ishii, R.; Kaharu, T.; Pirio, N.; Zhang, S.-W.; Takahashi, S. J .
Chem. Soc., Chem. Commun. 1995, 1215.
S0276-7333(96)00620-6 CCC: $14.00 © 1997 American Chemical Society

Gold(I)-Carbene Complexes
Sch em e 1
Organometallics, Vol. 16, No. 1, 1997 21
Sch em e 2
ally, we attempted to synthesize a variety of liquid-
crystalline gold-carbene complexes by the following
approaches: (1) using branched alcohols instead of
linear alcohols as a nucleophile; (2) synthesizing a
carbene complex containing an amino ligand with three
aromatic rings; (3) replacing the chlorine attached to
gold with sterically large iodine by a halogen exchange
reaction; (4) preparing a dinuclear gold-carbene com-
plex by reaction with a diamine.
Sch em e 3
Resu lts a n d Discu ssion
Syn th esis a n d Ch a r a cter iza tion . Examples of
thermally stable transition metal-carbene complexes
are platinum- and gold-carbene complexes, which can
be prepared from acetylide and isonitrile complexes by
the attack of appropriate nucleophiles at the positively
charged R-carbon atom of MCtCR and MCtNR.8 As
we have a variety of samples of liquid-crystalline
platinum- and gold-isonitrile complexes in our labora-
tory, we tried to convert them to liquid-crystalline
carbene complexes by the reaction with nucleophiles (eq
1). Treatment of bis(isonitrile)platinum(II) complexes
with amine nucleophiles gave bis(diaminocarbene)-
platinum(II) complexes, which have not yet been found
to exhibit mesomorphic properties.9
reactions with alcohols and amines.10 For example, a
gold-isonitrile complex (Scheme 1, n ) 11, m ) 2) was
suspended in ethanol and stirred at 65 °C under
nitrogen for 12 h, to give carbene complex 1e (n ) 11,
m ) 2) as white crystals in 70-80% yield after recrys-
tallization from CH2Cl2/hexane. Several gold(I)-diami-
nocarbene complexes were similarly prepared by adding
secondary and primary amines to CH2Cl2 or benzene
suspensions of the gold-isonitrile complexes at room
temperature. The products thus obtained are numbered
as shown in Schemes 2 and 3. Gold(I)-(alkoxy)(amino)-
carbene complexes containing three aromatic rings and
branched alkoxy groups were prepared similarly. The
yields of the products and the results of elemental
analyses are summarized in Table 5 (see Experimental
Section).
Our previous work showed that the rodlike structure
of gold(I)-isonitrile complexes with a two-coordination
geometry is quite suitable for the formation of liquid
crystals and even a rather large lateral group does not
disturb the mesophase stability but leads to a favorable
lowering of the transition temperatures.5 On the basis
of this finding, we transformed gold-isonitrile com-
plexes to carbene complexes by the nucleophilic addition
All the gold-carbene complexes were identified by
elemental and spectral analyses including IR and NMR
spectra. For example, the infrared spectrum of 1e
showed the disappearance of the CtN band at 2240
cm-1 for the corresponding isonitrile complex and the
appearance of two new bands at 3230 and 1550 cm-1
attributable to ν(NH) and ν(CdN), respectively. The 13
C
NMR spectrum displays a carbene carbon at δ 208 ppm,
indicating that 1e is a gold-(alkoxy)(amino)carbene
complex.
The detailed spectral analyses for 1 suggests the
existence of two geometrical isomers (ca. 3:1 ratio) due
(8) (a) Chisholm, M. H.; Clark, H. C. Inorg. Chem. 1971, 10, 1711.
(b) Badley, E. M.; Chatt, J .; Richards, R. L.; Sim, G. A. J . Chem. Soc.,
Chem. Commun. 1969, 1322. (c) Bonati, F.; Minghetti, G. J . Organomet.
Chem. 1970, 24, 251; 25, 255. (d) Miller, J . S.; Balch, A. L. Inorg. Chem.
1972, 11, 2069. (e) Parks, J . E.; Balch, A. L. J . Organomet. Chem. 1974,
71, 453. (f) Banditelli, G.; Bonati, F.; Calogero, S.; Valle, G. J .
Organomet. Chem. 1984, 275, 153.
(10) Bonati, F.; Minghetti, G. Syn. Inorg. Met.-Org. Chem. 1971, 1,
299.
(11) Bonati, F.; Minghetti, G. J . Organomet. Chem. 1973, 59, 403.
(9) Zhang, S.-W.; Kaharu, T.; Pirio, N.; Ishii, R.; Uno, M.; Takahashi,
S. J . Organomet. Chem. 1995, 489, C62.

22 Organometallics, Vol. 16, No. 1, 1997
Zhang et al.
(NHC6H4CH3-p)} (1.983(3) Å)12a and cationic Au{C-
+
(OC2H5)(NHC6H4CH3-p)}2 (2.02(2) Å).12b The C(1)-
Au(1)-Cl(1) angle is 176.2(2)°, showing a linear dico-
ordinate structure of gold(I), and the two planes of the
aromatic rings are almost perpendicular to each other.
It has been reported that only weak intermolecular
interaction can be expected when the Au---Au distance
of is over the range 2.75-3.40 Å.5,6c Since the shortest
intermolecular Au---Au distance present is >4 Å, it is
inferred that there are no Au---Au interactions. This
may account for the large reduction in the clearing
temperature. By utilization of the IR and 1H NMR
spectral data, the E- and Z-isomers of all the gold(I)-
carbene complexes can be clearly distinguished, and the
mesomorphic properties are attributed to the isolated
isomers.
Figu r e 1. Crystal structure of (E)-ClAu{C(OC2H5)(NHC6H4-
CO2C6H4OC2H5)}. Selected bond distances (Å) and angles
(deg) are as follows: Au(1)-C(1) ) 1.985(7), Au(1)-Cl(1)
) 2.277(2), C(1)-N(1) ) 1.325(9), C(1)-O(1) ) 1.317(8);
C(1)-Au(1)-Cl(1) ) 176.2(2), H(1)-N(1)-C(1) ) 117.9,
O(1)-C(1)-N(1) ) 113.0(6).
Th er m a l Beh a vior of Gold (I)-Ca r ben e Com -
p lexes. The carbene complexes obtained above exhibit
mesomorphic properties. For example, crystals of 1e
melt at 146 °C to form a smectic A (SA) phase, which
transforms to an isotropic phase at 160 °C with slight
decomposition. The mesophases were identified on the
basis of optical textures, and cooling 1e from an isotropic
phase shows a focal conic texture after the initial
appearance of baˆtonnets.
to the partial double-bond character of the C-N bond
which was observed in the infrared spectra.12 For
example, 1e shows two bands at 1730 and 1710 cm-1
assigned to the ester CdO. In addition, 1H NMR
spectrum shows two sets of signals due to the amide
proton and the protons on the neighboring aromatic ring
which allows the isomer ratio to be estimated by
analysis of the 1H NMR spectrum. The geometrical
isomers exist as a thermodynamic mixture in a solution,
and one of the isomers is a little more stable. The
isomers of 1 can be separated from each other by
fractional crystallization from CHCl3/Et2O12 or CH2Cl2/
C6H14 because one of them is less soluble than the other.
Complete separation of the isomers was successful with
the complexes which have short alkoxy groups. How-
ever, for the complexes having rather long alkoxy groups
could not be separated as they have almost the same
solubility. The pure E- and Z-isomers are stable in the
solid state, but they both isomerize even at room
temperature in a chloroform solution to give an equi-
librium mixture of E- and Z-forms.
The phase behaviors of each isomer of 1b,e,f and an
isomeric mixture of 1 are summarized in Table 1. The
gold(I)-(alkoxy)(amino)carbene complexes prepared in
the present work exhibit a stable SA phase, and those
having a lateral alkoxy group with less than four carbon
atoms exhibit an enantiotropic transition with slight
decomposition at the clearing point. To our surprise,
in spite of having a large lateral group, 1h was found
to be mesomorphic although the transition is monotro-
pic. In contrast to gold-isonitrile complexes, a favor-
able decrease of transition temperatures is attained for
the carbene complexes, in which the lateral group
probably improves the mesophase stability by inter-
rupting the strong intermolecular interactions between
two-coordinate gold(I) molecules. Comparison between
the E-isomer and Z-isomer showed no obvious differ-
ences of phase behavior and transition temperatures
except for the initial melting points. This is reasonable
because the transition from a crystalline phase of either
pure E- or Z-isomer to an SA phase could result in
isomerization to a thermodynamic mixture of the two
isomers. In fact, the isomerization between the E- and
Z-isomers has been confirmed to proceed not only in
solutions but also in the melt. The crystals obtained
by rapidly cooling the melted E- and Z-isomers of 1b
after heating to 150 and 155 °C, respectively, consist of
a mixture of E- and Z-isomers with different ratios. The
solids obtained from the isotropic liquids were confirmed
to comprise two isomers with an E/Z molar ratio of ca.
3:1 (Table 2), which is the same as the equilibrium ratio
observed in a chloroform solution. The fact that the two
pure isomers have different melting points and the same
clearing temperatures is consistent with the above
observation.
Z
E
To distinguish the E-isomer from the Z-isomer by
spectral methods, we have synthesized a gold(I)-
(alkoxy)(amino)carbene complex, ClAu{C(OC2H5)(NHC6-
H4CO2C6H4OC2H5)}, as a model complex for 1. The
single-crystal X-ray structural determination of the less
soluble isomer revealed that the complex exhibits an
E-form around the C-N bond and thus an extended
linear structure with an alkoxy lateral group. The
molecular structure and the atom-labeling scheme of
(E)-ClAu{C(OC2H5)(NHC6H4CO2C6H4OC2H5)} are pre-
sented in Figure 1. The Au---Ccarbene distance of 1.985-
(7) Å is similar to those reported for ClAu{C(OC2H5)-
In order to extend the range of liquid-crystallinity of
the gold-carbene complexes, we replaced the -COO-
joint combining the two aromatic rings of the isonitrile
ligands by -OCO-, -CtC-, and -CH2CH2- groups.
The results are summarized in Table 3. All of the gold-
carbene complexes 2 having a -OCO- joint showed
(12) (a) Banditelli, G.; Bonati, F.; Calogero, S.; Valle, G.; Wagner,
F. E.; Wordel, R. Organometallics 1986, 5, 1346. (b) Minghetti, G.;
Baratto, L.; Bonati, F. J . Organomet. Chem. 1975, 102, 397.

Gold(I)-Carbene Complexes
Organometallics, Vol. 16, No. 1, 1997 23
Ta ble 1. P h a se Tr a n sition Tem p er a tu r es (°C) for Com p lex 1
Ta ble 2. E/Z Ra tios of 1b (n ) 10, m ) 2)
Sch em e 4
Isom er a tion a t Melted Sta tesa
solid
150 °C
155 °C
165 °C
E-isomer
Z-isomer
1/0
0/1
2.4/1
1/1
3.6/1
2.9/1
3.4/1
2.3/1
a
Determined by means of 1H NMR data after rapidly cooling
the samples at the temperature.
Ta ble 3. P h a se Tr a n sition Tem p er a tu r es (°C) for
Com p lexes 2-4
did not. Replacement by a -CH2CH2- joint group
resulted in loss of mesomorphic properties as seen in
complex 4.
Second, instead of a linear alcohol, we employed a
branched alcohol in the preparation of the carbene
complexes. Complex 5 prepared with 3-methylbutanol
showed a monotropic S phase (Scheme 4). However, in
the cases of 2-propanol and 1-methylpropanol, no mes-
ophases were observed. Carbene complex 6 contains
three aromatic rings and showed an smectic phase, but
it decomposed before the transition to the isotropic
phase. This result is probably due to the high transition
temperature (Scheme 5). The carbene complexes with
three aromatic rings obtained from other alcohols or
amines did not show improved mesomorphic character-
istics.
a
b
With some decomposition. Unidentified phases.
mesogenic properties but with only generated monotro-
pic character. Comparison between 1b and 2b (n ) 10,
m ) 2), both of which are regioisomers, reveals that 1b
formed a stable SA phase while 2b gave a monotropic
SA phase with a lower melting temperature. The
carbene complexes 3p (n ) 8, m ) 2) and 3q (n ) 8, m
) 3) having a -CtC- joint group showed mesomorphic
properties, while the remaining two complexes, 3b,c,
We prepared an iodogold-carbene complex by a
halogen exchange reaction. Because direct exchange
reaction with the chlorogold-carbene complexes failed
to produce pure iodide derivatives, an alternative
synthetic route was taken as shown in Scheme 6. An
iodogold-isonitrile complex was first prepared by treat-
ment of a chloro analog with LiI in acetone13 and then
transformed to an iodogold-carbene complex by reac-

24 Organometallics, Vol. 16, No. 1, 1997
Zhang et al.
Sch em e 5
Sch em e 7
Sch em e 6
The absence of mesomorphic properties for complexes
8 may be attributed to bulky dialkyl lateral groups
which are unsuitable for the formation of mesophases.
An illustration is the fact that 9c having a lateral
butylamino group showed a monotropic SA phase while
8c which bears both methyl and butyl substitutes on
the amino group did not exhibit mesomorphic proper-
ties. It is noteworthy that a dinuclear gold-carbene
complex 10, prepared from N,N′-dimethyl-1,6-diamino-
hexane, formed a smectic mesophase although it de-
composed before transition to an isotropic phase (Scheme
7). Efforts to extend the liquid-crystalline behavior of
carbene complexes to other transition metals is in
progress.
Ta ble 4. P h a se Tr a n sition Tem p er a tu r es (°C) for
Com p lexes 8 a n d 9
Con clu sion s
This report provides the first detailed report of liquid-
crystalline metal-carbene complexes. Both gold(I)-
(alkoxy)(amino)carbene complexes and gold(I)-diami-
nocarbene complexes show mesogenic behaviors, and in
particular, the former display enantiotropic SA phases
with lower clearing temperatures than the correspond-
ing gold-isonitrile complexes. The structure of a model
complex has been determined by X-ray crystallography,
which suggests that the introduction of lateral alkyl
groups weakens intermolecular interactions. Two kinds
of geometric isomers, E and Z, exist for the gold(I)-
carbene complexes, which can be separated by fractional
recrystallization. The E-isomers show the almost same
thermal behavior as the Z-isomers with the exception
of their melting points. This effect is due to isomeriza-
tion which occurs during heating to afford an equilib-
rium mixture of E- and Z-isomers with a 3:1 molar ratio.
A dinuclear gold-carbene complex can be prepared by
using a diamine nucleophile. However, these new
carbene complexes decompose in the mesophases before
reaching their clearing point due to their high transition
temperatures.
a
With some decomposition.
tion with an alcohol nucleophile. The resulting complex
7 shows a higher melting point than the corresponding
chloro derivative 1f and decomposes before reaching the
isotropic temperature.
Finally, we prepared gold(I)-diaminocarbene com-
plexes 8 and 9 (Scheme 3), some of which exhibit
mesomorphic behavior. Their phase transition temper-
atures are summarized in Table 4. Complexes 8 were
prepared from secondary amines and did not show any
mesomorphic properties. In contrast complexes 9,
prepared from primary amines, formed SA phases
although they gradually decompose in the SA phases.
Exp er im en ta l Section
Gold-isonitrile complexes were prepared by the known
methods.5 Elemental microanalyses were performed by the
Material Analysis Center, ISIR, Osaka University (Table 5).
IR spectra were obtained with a Perkin-Elmer 2000 FT-IR
system. 1H NMR spectra were recorded on a Brucker WM-
(13) Benouazzane, M.; CoCo, S.; Espinet, P.; Martin-Alvarez, J . J .
Mater. Chem. 1995, 5, 441.

Gold(I)-Carbene Complexes
Organometallics, Vol. 16, No. 1, 1997 25
Ta ble 5. Yield s a n d Elem en ta l An a lyses of
1.74 (m, 2H, OCH2CH2C8H17), 1.59-1.49, 1.46-1.18 (m, 17H,
OCH2CH3, O(CH2)2(CH2)7CH3), 0.89 (t, 3H, J ) 6.9 Hz,
O(CH2)9CH3); 13C-NMR (CDCl3) δ 208.4 (AudC), 164.5 (CdO),
157.1, 131.4, 128.6, and 115.2 (HNC6H4CO2), 144.1, 140.1,
123.7, and 122.7 (CO2C6H4OC10H21), 76.6 (OCH2CH3), 68.5
(OCH2C9H19), 31.9, 30.1, 29.6, 29.4, 29.3, 26.1, 25.9, and 22.7
(OCH2C8H16CH3), 15.1 (OCH2CH3), 14.1 (OC9H18CH3).
Ch lor o[(p r op oxy){(4-((4′-(n -d e cyloxy)b e n zoyl)oxy)-
p h en yl)a m in o}ca r ben e]gold (2c). A solution of chloro[4-
((4′-(n-decyloxy)benzoyl)oxy)phenyl isonitrile]gold (91.6 mg,
0.150 mmol) in propanol (15 mL) was stirred at 65 °C under
nitrogen atmosphere for 12 h. The solvent was removed on a
rotary evaporator, and the residue was recrystallized from
CHCl3/Et2O to give a white powder of product as an isomeric
mixture (85.4 mg, 85%): IR (KBr) 3296, 3236 (νN-H), 1713,
1724 (νCdO), 1545, 1549 (νCdN) cm-1; 1H-NMR (270 MHz, CDCl3)
δ 10.09, 9.08 (s, 1H, NH), 8.13 (m, 2H, Ar), 7.61, 7.49 (m, 2H,
Ar), 7.30-7.21 (m, 2H, Ar), 6.98 (m, 2H, Ar), 4.82-4.76 (m,
2H, OCH2CH2CH3), 4.04 (t, 2H, J ) 6.4 Hz, OCH2C9H19), 1.93-
1.80 (m, 4H, OCH2CH2CH3 OCH2CH2C8H17), 1.59-1.28 (m,
17H, OCH2CH2CH3, O(CH2)2(CH2)7CH3), 0.89 (t, 3H, J ) 6.6
Hz, O(CH2)9CH3).
Gold (I)-Ca r ben e Com p lexes 1-10
anal. (%): found (calcd)
com- yield
plex (%)
C
H
N
Cl(I)
1a
1b
1c
1d
1e
1f
1g
1h
1j
1k
1m
2b
2c
2m
3b
3c
3p
3q
4
75 46.81 (46.63) 5.22 (5.17) 2.20 (2.18) 5.33 (5.51)
76 47.15 (47.46) 5.26 (5.36) 2.05 (2.13) 5.34 (5.39)
78 48.41 (48.26) 5.62 (5.55) 2.01 (2.08) 5.10 (5.28)
74 49.20 (49.02) 5.67 (5.73) 2.01 (2.04) 5.28 (5.17)
87 48.18 (48.26) 5.30 (5.52) 2.28 (2.08) 5.01 (5.28)
76 49.03 (49.02) 5.70 (5.73) 1.97 (2.04) 5.12 (5.17)
83 49.57 (49.76) 5.75 (5.90) 1.97 (2.00) 5.05 (5.06)
75 50.40 (50.46) 6.00 (6.07) 1.84 (1.96) 5.01 (4.96)
87 48.73 (49.02) 5.69 (5.73) 1.95 (2.04) 5.30 (5.17)
59 49.93 (49.76) 5.79 (5.90) 1.93 (2.00) 5.15 (5.06)
47 50.64 (50.46) 5.97 (6.07) 1.81 (1.96) 4.75 (4.96)
93 47.26 (47.46) 5.21 (5.36) 2.03 (2.13) 5.30 (5.39)
85 48.43 (48.26) 5.48 (5.52) 2.03 (2.08) 5.18 (5.28)
40 50.25 (50.46) 6.05 (6.07) 1.89 (1.96) 4.74 (4.96)
90 50.64 (50.83) 5.30 (5.53) 2.11 (2.20) 5.78 (5.56)
85 51.30 (51.58) 5.51 (5.72) 2.14 (2.15) 5.32 (5.44)
68 48.96 (49.23) 4.90 (5.12) 2.43 (2.30) 5.65 (5.81)
69 49.95 (50.05) 5.11 (5.33) 2.18 (2.24) 5.65 (5.68)
81 48.62 (48.91) 5.50 (5.75) 2.09 (2.28) 5.88 (5.77)
90 50.68 (50.46) 6.01 (6.07) 1.85 (1.96) 4.69 (4.96)
26 50.97 (51.04) 4.85 (5.00) 1.91 (1.98) 5.28 (5.02)
42 51.21 (51.04) 4.91 (5.00) 1.87 (1.98) 5.26 (5.02)
82 43.28 (43.26) 4.94 (5.06) 1.59 (1.80) 16.55 (16.32)
90 48.91 (49.09) 5.71 (5.89) 4.30 (4.09) 5.27 (5.18)
93 49.15 (49.09) 5.76 (5.89) 3.93 (4.09) 5.00 (5.18)
73 51.00 (51.21) 6.31 (6.38) 3.62 (3.85) 4.66 (4.88)
47 48.54(48.33) 5.56 (5.71) 3.98 (4.17) 5.35 (5.28)
41 50.04 (49.83) 5.99 (6.06) 3.93 (4.01) 5.03 (5.07)
59 50.30 (50.53) 6.12 (6.22) 3.85 (3.93) 5.13 (4.97)
82 50.71 (50.60) 6.08 (6.09) 3.80 (3.93) 4.99 (4.98)
5
Ch lor o[(et h oxy){(4-((4′-(n -oct yloxy)p h en yl)et h yn yl)-
p h en yl)a m in o}ca r ben e]gold (3p ). A solution of chloro[4-
((4′-(n-octyloxy)phenyl)ethynyl)phenyl isonitrile]gold (90 mg,
0.16 mmol) in ethanol (15 mL) was stirred at 65 °C under
nitrogen atmosphere for 12 h. The solvent was removed on a
rotary evaporator, and the residue was recrystallized from
CH2Cl2/hexane to give a white powder of product as an
isomeric mixture (67 mg, 68%): IR (KBr) 3223 (νN-H), 2216
6a
6b
7
8a
8b
8c
9a
9b
9c
10
1
(νCtC), 1541 (νCdN) cm-1; H-NMR (270 MHz, CDCl3) δ 9.88,
8.88 (s, 1H, NH), 7.56-7.40 (m, 6H, Ar), 6.89-6.83 (m, 2H,
Ar), 4.90 (dq, 2H, J ) 7.0, 2.0 Hz, OCH2CH3), 3.97 (t, 2H, J )
6.6 Hz, OCH2C7H15), 1.82-1.74 (m, 2H, OCH2CH2C6H13),
1.56-1.29 (m, 13H, OCH2CH3, O(CH2)2(CH2)5CH3), 0.89 (t, 3H,
J ) 6.7 Hz, O(CH2)7CH3).
360 spectrometer in CDCl3 with tetramethylsilane as an
internal standard. The textures of liquid crystals were
observed using an Olympus BH-2 polarizing microscope in
conjunction with a Mettler FP 52 hot-stage and FP 5 control
unit, and phase transition temperatures were also determined
using a Shimazu DSC-50 differential scanning calorimeter.
Representative preparation procedures and physical data for
gold-carbene complexes are given below.
Ch lor o[(e t h oxy){(4-((4′-(n -oct yloxy)p h e n yl)e t h yl)-
p h en yl)a m in o}ca r ben e]gold (4). A solution of chloro[4-((4′-
(n-octyloxy)phenyl)ethyl)phenyl isonitrile]gold (74 mg, 0.13
mmol) in ethanol (15 mL) was stirred at 65 °C under nitrogen
atmosphere for 12 h. The solvent was removed on a rotary
evaporator, and the residue was recrystallized from CH2Cl2/
hexane to give a white powder of product as an isomeric
Ch lor o[(eth oxy){(4-((4′-(n -d ecyloxy)p h en yl)ca r bon yl)-
p h en yl)a m in o}ca r ben e]gold (1b). A solution of chloro[4-
((4′-(n-decyloxy)phenyl)carbonyl)phenyl isonitrile]gold (207 mg,
0.34 mmol) in ethanol (15 mL) was stirred at 65 °C under
nitrogen atmosphere for 12 h. The solvent was removed on a
rotary evaporator, and the residue was recrystalized from
CHCl3/Et2O to give a white powder of product as a mixture of
E- and Z-isomers (169 mg, 76% yield). By fractional recrys-
tallization from CHCl3, pure Z-isomer was obtained as a white
powder (30 mg, 13%) at the first cycle. After removal of the
solvent of the mother liquor, the residue was recrystalized from
CHCl3/Et2O again. The same operation was repeatedly carried
out, and finally the E-isomer was also separated as a white
powder. (Z)-Chloro[(ethoxy){4-((4′-(n-decyloxy)phenyl)carbon-
yl)phenylamino}carbene]gold: IR (KBr) 3230 (νN-H), 1714
(νCdO), 1546 (νCdN), 1249, 1193, 1088 (νC-O) cm-1; 1H-NMR (270
MHz, CDCl3) δ 8.99 (s, 1H, NH), 8.28 (m, 2H, Ar), 7.77 (m,
2H, Ar), 7.11 (m, 2H, Ar), 6.93 (m, 2H, Ar), 4.94 (q, 2H, J )
7.0 Hz, OCH2CH3), 3.96 (t, 2H, J ) 6.6 Hz, OCH2C9H19), 1.84-
1.74 (m, 2H, OCH2CH2C8H17), 1.59-1.49, 1.46-1.18 (m, 17H,
OCH2CH3, O (CH2)2(CH2)7CH3), 0.89 (t, 3H, J ) 6.9 Hz,
O(CH2)9CH3); 13C-NMR (CDCl3) δ 208.0 (AudC), 164.0 (CdO),
157.1, 131.4, 128.8, and 115.2 (HNC6H4CO2), 144.1, 139.9,
122.7, and 122.2 (CO2C6H4OC10H21), 76.2 (OCH2CH3), 68.5
(OCH2C9H19), 32.1, 31.9, 30.0, 29.6, 29.4, 26.3, 26.1, and 22.7
(OCH2C8H16CH3), 15.1 (OCH2CH3), 14.1 (OC9H18CH3). (E)-
Chloro[(ethoxy){4-((4′-(n-decyloxy)phenyl)carbonyl)phenylami-
no}carbene]gold: IR (KBr) 3305 (νN-H), 1733 (νCdO), 1548
mixture (65 mg, 81%): IR (KBr) 3233 (νN-H), 1537 (νCdN) cm-1
;
1H-NMR (270 MHz, CDCl3) δ 9.47, 8.81 (s, 1H, NH), 7.46-
7.15 (m, 4H, Ar), 7.04 (m, 2H, Ar), 6.84-6.79 (m, 2H, Ar), 4.86
(q, 2H, J ) 6.9 Hz, OCH2CH3), 3.92 (dt, 2H, J ) 6.6, 1.7 Hz,
OCH2C7H15), 2.87-2.07 (m 4H, Ph(CH2)2Ph), 1.82-1.72 (m,
2H, OCH2CH2C6H13), 1.56-1.25 (m, 13H, OCH2CH3, O(CH2)2-
(CH2)5CH3), 0.89 (t, 3H, J ) 6.9 Hz, O(CH2)7CH3).
Ch lor o[(3-m eth ylbu toxy){(4-((4′-(u n d ecyloxy)p h en yl)-
ca r bon yl)p h en yl)a m in o}ca r ben e]gold (5). A solution of
chloro[4-((4′-(undecyloxy)phenyl)carbonyl)phenyl isonitrile]gold
(161 mg, 0.26 mmol) in 3-methylbutanol (12 mL) was stirred
at 65 °C under nitrogen atmosphere for 12 h. The solvent was
removed on a rotary evaporator, and the residue was recrys-
tallized from CH2Cl2/hexane to give a white powder of product
as an isomeric mixture (165 mg, 90%): IR (KBr) 3235, 3200
(νN-H), 1720, 1712 (νCdO), 1542, 1530 (νCdN) cm-1; 1H-NMR (270
MHz, CDCl3) δ 10.02, 9.00 (s, 1H, NH), 8.27, 8.22 (d, d, 2H,
Ar), 7.78, 7.56 (d, d, 2H, Ar), 7.14-7.08 (m, 2H, Ar), 6.96-
6.91 (m, 2H, Ar), 4.93-4.86, 4.81-4.46 (m, 2H, OCH2CH2CH2-
(CH3)2), 3.96 (t, 2H, J ) 6.4 Hz, OCH2C10H21), 1.93-1.80 (m,
4H, OCH2CH2CH2(CH3)2, OCH2CH2C9H19), 1.59-1.28 (m, 18H,
OCH2CH2CH2(CH3)2, O(CH2)2(CH2)8CH3), 1.10-0.89 (m, 9H,
OCH2CH2CH2(CH3)2, O(CH2)9CH3).
Ch lor o[(eth oxy){(4-((4′′-(n -octyloxy)diph en yl)car bon yl)-
p h en yl)a m in o}ca r ben e]gold (6). To the solution of chloro-
[(ethoxy){4-((4′′-(n-octyloxy)diphenyl)carbonyl)phenyl isocyanide]-
gold (69 mg, 0.105 mmol) in CHCl3 (10 mL) was added ethanol
(20 mL). After the solution was stirred for 18 h at 65 °C under
nitrogen in dark, the solvent was evaporated and the resultant
(νCdN), 1245, 1192, 1074 (νC-O) cm-1 1H-NMR (270 MHz,
;
CDCl3) δ 10.38 (s, 1H, NH), 8.23 (m, 2H, Ar), 7.62 (m, 2H,
Ar), 7.11 (m, 2H, Ar), 6.96 (m, 2H, Ar), 4.98 (q, 2H, J ) 7.0
Hz, OCH2CH3), 3.96 (t, 2H, J ) 6.6 Hz, OCH2C9H19), 1.84-

26 Organometallics, Vol. 16, No. 1, 1997
Zhang et al.
residue was purified by recrystallization from CH2Cl2/hexane.
The crystals in the first cycle was collected as the Z-isomeric
product (19.4 mg, 26%). At the second cycle, a white powder
was found to be the E-isomeric product (30.9 mg, 42%). The
third recrystallization from CH2Cl2/hexane gave a white
powder product as an isomeric mixture. (Z)-Chloro[(ethoxy)-
{(4-((4′′-(n-octyloxy)diphenyl)carbonyl)phenyl)amino}carbene]-
gold: IR (KBr) 3226 (νN-H), 1713 (νCdO), 1547 (νCdN); 1H-NMR
(270 MHz, CDCl3) δ 9.01 (s, 1H, NH), 8.31 (d, 2H, J ) 8.6 Hz,
Ar), 7.79 (d, 2H, J ) 8.6 Hz, Ar), 7.60 (d, 2H, J ) 8.6 Hz, Ar),
7.51 (d, 2H, J ) 8.9 Hz, Ar), 7.26 (d, 2H, J ) 8.6 Hz, Ar), 6.98
(d, 2H, J ) 8.6 Hz, Ar), 4.95 (q, 2H, J ) 7.1 Hz, OCH2CH3),
4.00 (t, 2H, J ) 6.4 Hz, OCH2C7H15), 1.84-1.76 (m, 2H,
OCH2CH2C6H13), 1.57-1.52, 1.30-1.25 (m, 13H, OCH2CH3,
O(CH2)2(CH2)5CH3), 0.90-0.87 (m, 3H, O(CH2)7CH3). (E)-
Chloro[(ethoxy){(4-((4′′-(n-octyloxy)diphenyl)carbonyl)phenyl)-
amino}carbene]gold: IR (KBr) 3228 (νN-H), 1727 (νCdO), 1553
(t, 2H, J ) 7.3 Hz, NCH2(CH2)CH3), 3.96 (t, 2H, J ) 6.4 Hz,
OCH2C11H23), 3.69, 3.16 (s, 3H, NCH3), 1.84-1.67 (m, 4H,
NCH2CH2C2H5, OCH2CH2(CH2)8CH3), 1.46-1.27 (m, 20H,
N(CH2)2CH2CH3, O(CH2)2(CH2)9CH3), 1.06-0.96 (m, 3H, N-
(CH2)3CH3), 0.88 (t, 3H, J ) 6.8 Hz, O(CH2)11CH3).
Ch lor o[(p r op yla m in o){(4-((4′-(n -d od ecyloxy)p h en yl)-
ca r bon yl)p h en yl)a m in o}ca r ben e]gold (9a ). To the solu-
tion of chloro[4-((4′-(n-dodecyloxy)phenyl)carbonyl)phenyl isoni-
trile]gold (84.1 mg, 0.131 mmol) in benzene (20 mL) was added
propylamine (0.022 mL, 0.26 mmol). After the solution was
stirred for 5 h at room temperature under nitrogen, the solvent
was evaporated and the resultant residue was purified by
recrystallization from CH2Cl2/hexane. A white powder (42.7
mg, 47%) was obtained as an isomeric mixture: IR (KBr) 3299
(νN-H), 1732 (νCdO), 1560 (νCdN) cm-1 1H-NMR (270 MHz,
;
CDCl3) δ 8.20 (bd, 2.5-3H, NH, Ar), 7.84 (bs, -0.5H, NH),
7.75 (m, 2H, Ar), 7.36 (bs, 1H, NH), 7.12-7.07 (m, 2H, Ar),
6.94-6.87 (m, 2H, Ar), 3.95 (t, 2H, J ) 6.4 Hz, OCH2C11H23),
3.72, 3.27 (bm, 2H, NCH2C2H5), 1.81-1.73 (m, 2H, NCH2CH2-
CH3,), 1.71-1.67, 1.57-1.26 (m, 20H, NCH2CH2CH3, O(CH2)2-
(CH2)9CH3), 1.10, 0.97 (t, 3H, J ) 7.4, 6.6 Hz, N(CH2)2CH3),
0.88 (t, 3H, J ) 6.6 Hz, O(CH2)11CH3).
1
(νCdN); H-NMR (270 MHz, CDCl3) δ 10.22 (s, 1H, NH), 8.27
(d, 2H, J ) 8.9 Hz, Ar), 7.67-7.58 (m, 4H, Ar), 7.51 (d, 2H, J
) 8.6 Hz, Ar), 7.26 (d, 2H, J ) 8.6 Hz, Ar), 6.98 (d, 2H, J )
8.9 Hz, Ar), 4.96 (q, 2H, J ) 7.1 Hz, OCH2CH3), 4.00 (t, 2H, J
) 6.4 Hz, OCH2C7H15), 1.84-1.76 (m, 2H, OCH2CH2C6H13),
1.59-1.53, 1.30-1.25 (m, 13H, OCH2CH3, O(CH2)2(CH2)5CH3),
0.90-0.87 (m, 3H, O(CH2)7CH3).
Din u clea r Gold -Ca r ben e Com p lex, [ClAu {C(NHC6-
H4CO2C6H4OCn H2n +1)}](NCH3CmH2mNCH3)[ClAu {C(NHC6-
Iodo[(pr opoxy){(4-((4′-(n -u n decyloxy)ph en yl)car bon yl)-
p h en yl)a m in o}ca r ben e]gold (7). To a solution of chloro-
[(4-((4′-(n-undecyloxy)phenyl)carbonyl)phenyl isonitrile]gold
(281 mg, 0.50 mmol) in acetone (50 mL) was added LiI (301
mg, 2.5 mmol). After the solution was stirred for 12 h at room
temperature, the solvent was evaporated and benzene as
washing solvent was added to the resultant residue. Then the
precipitate was collected by filtration to give a yellow powder
as product, iodo[4-((4′-(n-undecyloxy)phenyl)carbonyl)phenyl
isonitrile]gold (281 mg, 87%). A solution of iodo[4-((4′(n-
undecyloxy)phenyl)carbonyl)phenyl isonitrile]gold (93 mg, 0.13
mmol) in propanol (15 mL) was stirred at 65 °C under nitrogen
atmosphere for 2 h. The solvent was removed on a rotary
evaporator, and the residue was recrystallized from CH2Cl2/
hexane to give a pale yellow powder product as an isomeric
mixture (83 mg, 82%): IR (KBr) 3224 (νN-H), 1727, 1713 (νCdO),
H4CO2C6H4OCn H2n +1)}] (10). To the solution of chloro[4-((4′-
(n-dodecyloxy)phenyl)carbonyl)phenyl isonitrile]gold (82.6 mg,
0.13 mmol) in CH2Cl2 (15 mL) was added N,N′-dimethyl-1,6-
hexamethylenediamine (0.01 mL, 0.065 mmol). The mixture
was stirred at room temperature under nitrogen for 1 h. The
solvent was evaporated and the resultant residue was purified
by recrystallization from CH2Cl2/hexane. A white powder (75.3
mg, 82%) was obtained as a product: IR (KBr) 3322 (νN-H),
1
1713 (νCdO), 1554 (νCdN) cm-1; H-NMR (270 MHz, CDCl3) δ
8.03 (d, 4H, J ) 7.9 Hz, Ar), 7.91 (s, 2H, NH), 7.64 (d, 4H, J
) 7.6 Hz, Ar), 7.09 (d, 4H, J ) 9.2 Hz, Ar), 6.85 (d, 4H, J )
9.2 Hz, Ar), 4.23 (m, 4H, (NCH2C2H4)2), 3.94 (t, 4H, J ) 6.6
Hz, (OCH2C11H23)2), 3.21 (m, 4H, (NCH2CH2CH2)2), 1.89-1.27
(m, 24H, (NC2H4CH2)2, OCH2CH2)8CH3), 1.46-1.27 (m, 20H,
N(CH2)2CH2CH3, (O(CH2)2(CH2)10CH3)2), 0.90 (t, 6H, J ) 6.9
Hz, (O(CH2)11CH3)2).
1
1549 (νCdN) cm-1; H-NMR (270 MHz, CDCl3) δ 9.07, 9.00 (s,
1H, NH), 8.26, 8.06 (m, 2H, Ar), 7.79, 7.50 (m, 2H, Ar), 7.13-
7.07 (m, 2H, Ar), 6.95-6.87 (m, 2H, Ar), 4.89 (dt, 2H, J ) 6.6,
2.1 Hz, OCH2CH2CH3), 3.96 (t, 2H, J ) 6.4 Hz, OCH2C10H21),
1.97-1.11 (m, 20H, OCH2CH2CH3, OCH2(CH2)9CH3), 1.05 (dt,
3H, OCH2CH2CH3), 0.89 (t, 3H, J ) 6.6 Hz, O(CH2)10CH3).
Ch lor o[(N-m eth yl-n -bu tylam in o){(4-((4′-(n -dodecyloxy)-
p h en yl)ca r bon yl)p h en yl)a m in o}ca r ben e]gold (8c). To
the solution of chloro[4-((4′-(n-dodecyloxy)phenyl)carbonyl)-
phenyl isonitrile]gold (83.6 mg, 0.131 mmol) in CH2Cl2 (15 mL)
was added N-methyl-n-butylamine (0.1 mL, 0.84 mmol). After
the solution was stirred for 3 h at room temperature under
nitrogen, the solvent was evaporated and the resultant residue
was purified by recrystallization from CH2Cl2/hexane. A white
powder (69.6 mg, 73%) was obtained as an isomeric mixture:
IR (KBr) 3338 (νN-H), 1741, 1708 (νCdO), 1552 (νCdN) cm-1; 1H-
NMR (270 MHz, CDCl3) δ 8.19 (m, 2H, Ar), 7.70 (m, 2H, Ar),
7.51 (s, 1H, NH), 7.10 (m, 2H, Ar), 6.93 (m, 2H, Ar), 4.08, 3.47
Ack n ow led gm en t. This work was supported in part
by grants from the ministry of Education, Science,
Sports, and Culture of J apan (Nos. 07740522 and
08740521). We thank the Material Analysis Center of
ISIR, Osaka University, for X-ray measurements and
elemental analyses.
Su p p or tin g In for m a tion Ava ila ble: Text describing
X-ray procedures, tables of crystal data and details of the
structure solution, positional and displacement parameters,
and bond distances and angles, and ORTEP diagrams (20
pages). Ordering information is given on any current mast-
head page.
OM9606202