Liquid-Crystalline Mono- And Dinuclear (Perhalophenyl)gold(I) Isocyanide Complexes

Article abstract of DOI:10.1021/ic960917s

Rodlike gold(I) and gold(III) complexes [AuR(C≡N(C₆H₄)_mOC_nH _2n+1-p)] (m = 1, n = 10, R = C₆F₅; m = 2, n = 4, 6, 8, 10, 12, R = C₆F₅, C₆F₄Br-o, C₆F₄Br-p), [(μ-4,4′C₆F₄C₆F ₄){AuC≡N(C₆H₄)_mOC _nH_2n+1}₂] (m = l, 2; n = 4, 6, 8, 10, 12), [AuRI₂(C≡NC₆H₄C₆H ₄OC_nH_2n+1-p)] (R = C₆F₅, n = 8; R = C₆F₄Br-o, n = 10), and [(μ-4,4′-C₆F₄C₆F₄){AuX ₂C≡N(C₆H₄)_mOC _nH_2n+1}₂] (m = l, 2; n = 4, 6, 8, 10, 12) have been prepared and their liquid crystal behavior has been studied. The gold(III) compounds are not mesomorphic, but all the perhalogold(I) derivatives described are liquid crystals except the phenyl isocyanide gold(I) derivative [Au(C₆F₅)(C≡NC₆H₄OC ₁₀H₂₁-p)]. The mononuclear derivatives show only a nematic (N) phase when the isocyanides have a short tail (n = 4), N and smectic A phases (S_A) when the isocyanides have an intermediate tail (n = 6, 8), and only S_A phases for longer chains. Their thermal stability is high, even in the isotropic state. The variation in transition temperatures is as follows: C₆F₄Br-p ≥ C₆F₅ > C₆F₄Br-o when n ≤ 6 and C₆F₄Br-p > C₆F₄Br-o > C₆F₅ for n ≥ 8. This behavior is understood on the basis of electronic and steric factors. The dinuclear compounds [(μ4,4′-C₆F₄C₆F ₄){AuC≡N(C₆H₄)_mOC _nH_2n+1}₂] display only N mesophases and all the biphenylisocyanide derivatives and phenyl isocyanide compounds with n ≤ 6 undergo some decomposition upon reaching the clearing point to the isotropic state.

Full text of DOI:10.1021/ic960917s

Inorg. Chem. 1997, 36, 2329-2334
2329
Liquid-Crystalline Mono- and Dinuclear (Perhalophenyl)gold(I) Isocyanide Complexes
Rocio Bayo´n, Silverio Coco, Pablo Espinet,*,† Ce´sar Ferna´ndez-Mayordomo, and
Jose´ M. Mart´ın-Alvarez
Departamento de Qu´ımica Inorga´nica, Facultad de Ciencias, Universidad de Valladolid,
E-47005 Valladolid, Spain
ReceiVed August 1, 1996X
Rodlike gold(I) and gold(III) complexes [AuR(CtN(C6H4)mOCnH2n+1-p)] (m ) 1, n ) 10, R ) C6F5; m ) 2, n
) 4, 6, 8, 10, 12, R ) C6F5, C6F4Br-o, C6F4Br-p), [(µ-4,4′-C6F4C6F4){AuCtN(C6H4)mOCnH2n+1}2] (m ) 1, 2;
n ) 4, 6, 8, 10, 12), [AuRI2(CtNC6H4C6H4OCnH2n+1-p)] (R ) C6F5, n ) 8; R ) C6F4Br-o, n ) 10), and
[(µ-4,4′-C6F4C6F4){AuX2CtN(C6H4)mOCnH2n+1}2] (m ) 1, 2; n ) 4, 6, 8, 10, 12) have been prepared and their
liquid crystal behavior has been studied. The gold(III) compounds are not mesomorphic, but all the perhalo-
gold(I) derivatives described are liquid crystals except the phenyl isocyanide gold(I) derivative [Au(C6F5)(CtNC6H4-
OC10H21-p)]. The mononuclear derivatives show only a nematic (N) phase when the isocyanides have a short
tail (n ) 4), N and smectic A phases (SA) when the isocyanides have an intermediate tail (n ) 6, 8), and only SA
phases for longer chains. Their thermal stability is high, even in the isotropic state. The variation in transition
temperatures is as follows: C6F4Br-p g C6F5 > C6F4Br-o when n e 6 and C6F4Br-p > C6F4Br-o > C6F5 for n
g 8. This behavior is understood on the basis of electronic and steric factors. The dinuclear compounds [(µ-
4,4′-C6F4C6F4){AuCtN(C6H4)mOCnH2n+1}2] display only N mesophases and all the biphenylisocyanide derivatives
and phenyl isocyanide compounds with n e 6 undergo some decomposition upon reaching the clearing point to
the isotropic state.
Introduction
tives; a few olefin complexes of Pt26,27 and Fe;28,29 a number of
alkynyl complexes of Ni, Pd, and Pt;30,31 some isocyanide
The continued development of liquid-crystal-based technolo-
gies requires mesomorphic materials with adequate physical
properties, and much research has been carried out in order to
design and prepare new liquid-crystalline materials. In the last
years metal-containing liquid crystals with transition or post-
transition metals (so-called metallomesogens) have seen sys-
tematic research and development.1-5 Most metallomesogens
are based on d8-d10 coordination compounds with planar or
linear geometries, but only a few examples of gold mesogens
have been reported. Moreover, the kinds of organometallic
liquid crystals known are rather limited: A vast family of
orthometalated derivatives of Pd6-16 and a few of Pt,17 Mn-
(I),18 and Re(I);19 some ferrocene20-24 and ruthenocene25 deriva-
complexes of Au,32-37 Pd, and Pt;38,39 and recently a few
(carbene)gold derivatives.40
In summary the reviews show the absence of metallome-
sogens based on molecules with metal-aryl bonds not involved
in a metallacycle, with the exception of bis(aryl)mercury
derivatives, which were the first metallomesogens described,41
and arylgermanium, -tin, and -lead derivatives.42
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† E-mail: espinet@cpd.uva.es.
X Abstract published in AdVance ACS Abstracts, April 15, 1997.
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S0020-1669(96)00917-2 CCC: $14.00 © 1997 American Chemical Society

2330 Inorganic Chemistry, Vol. 36, No. 11, 1997
Bayo´n et al.
On the other hand, there has been an increasing interest in
liquid crystals containing fluorine atoms in the backbone
structure,43-47 due to the fact that fluorination of conventional
organic liquid crystals produces important changes on the
melting temperatures, viscosity, birefringence, dielectric ani-
sotropy, and mesophase stability.48,49 However only a limited
number of metal complexes with fluorinated ligands have been
reported.50-53
Scheme 1
We have reported previously a family of gold complexes
[AuX(CtNC6H4OCnH2n+1-p)] (X ) halogen) which show
smectic A phases in spite of the fact that their isocyanide ligands
are not mesogenic and contain only one aryl ring. These
complexes show the induction of mesogenic behavior by the
presence of a metal atom that increases the polarizability of the
molecule.34 On this simple mesogenic system, we have studied
the effect of modifications in the isocyanide group on the
mesogenic properties. Thus, similar gold(I) biphenyl, 2-fluo-
rophenyl, and 3-fluorophenyl isocyanide complexes show mostly
SA mesophases, and gold(I) 3,4,5-trialkoxyphenyl isocyanide
derivatives show hexagonal columnar mesophases.36,37
In this paper we report the preparation and thermal behavior
of uncommon mesogens containing only M-C σ-bonds, based
on mono- and dinuclear (perhalophenyl)gold(I) isocyanide
compounds of type [AuR(CtNC6H4C6H4OCnH2n+1-p)] (R )
C6F5, C6F4Br-o, C6F4Br-p) and [(µ-4,4′-C6F4C6F4){AuCtN-
(C6H4)mOCnH2n+1}2] (m ) 1, 2).
Results and Discussion
Synthesis and Characterization. The gold(I) isocyanide
complexes and their corresponding gold(III) derivatives have
been prepared as described in the literature for similar (pen-
tafluorophenyl)gold(I) and -gold(III) isocyanide derivatives and
(4,4′-octafluorobiphenyl)gold(I) complexes, respectively,54,55 as
represented in Schemes 1 and 2 (tht ) tetrahydrothiophene).
[AuR(CtN(C6H4)mOCnH2n+1-p)] (series I: m ) 1, n ) 10, R
) C6F5; m ) 2, n ) 4, 6, 8, 10, 12, R ) C6F5, C6F4Br-o, C6F4-
Br-p) and [(µ-4,4′-C6F4C6F4){AuCtN(C6H4)mOCnH2n+1}2] (se-
ries III: m ) 1, 2) are obtained in two steps by arylation of
[AuCl(tht)] followed by ligand exchange with the appropriate
isocyanide. Oxidative addition of halogen yields the corre-
sponding gold(III) derivatives (series II and IV).
The C, H, N analyses for the complexes, yields, and relevant
IR data are given in the Experimental Section. The IR spectra
are all similar and show one ν(CtN) absorption for the
isocyanide group at higher wavenumbers (ca. 90 cm-1) than
for the free isocyanide, as has been reported for other gold(I)
isocyanide compounds.34-36,54
(36) Benouazzane, M.; Coco, S.; Espinet, P.; Mart´ın-Alvarez, J. M. J. Mater.
Chem. 1995, 5, 441.
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19.
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1994, 4, 859.
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Soc., Chem. Commun. 1995, 1215.
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Trans. 1989, 2, 2041.
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Wiley: Chichester, U.K., 1987.
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Chem. 1992, 2, 65.
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1990, 8, 513.
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200, 109.
1
The H NMR spectra of gold(I) and gold(III) isocyanide
complexes prepared are all very similar, showing at 300 MHz
respectively four or two somewhat distorted “doublets” for the
biphenyl (strictly two AA′XX′ spin systems) or the phenyl group
(one AA′XX′ spin system), as we have reported for similar
halogold(I) isocyanide complexes.34,36
The 19F NMR spectra of these complexes show the typical
patterns of the corresponding perhalophenyl group. Thus, the
C6F5 derivatives show the three resonances expected from an
AA′MXX′ spin system.56 The C6F4Br-o complexes show four
signals (first order, AKRX spin system). The two low-field
signals (doublets of doublets) appear at ca. -116 ppm and ca.
-127 ppm (reference CFCl3) and are assigned to F(ortho) and
F(ortho to Br), respectively. The two high-field signals appear
at ca. -156 and -157 ppm and are assigned to F(para) and
F(meta), respectively. Note that in the precursors [AuR(tht)]
(R ) C6F5, C6F4Br-o, tht ) tetrahydrothiophene), the signal of
F(para) appears at lower field than for CNR derivatives. This
suggest that, upon substitution of tht for isocyanide, which is a
good π acceptor ligand, the R group becomes more electron
donating producing a deshielding mainly in the para position.
(54) Uso´n, R.; Laguna, A.; Vicente, J.; Garc´ıa, J.; Bergareche, B.; Brun,
P. Inorg. Chim. Acta 1978, 28, 237.
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(Perhalophenyl)gold(I) Isocyanide Complexes
Inorganic Chemistry, Vol. 36, No. 11, 1997 2331
Table 1. Optical, Thermal, and Thermodynamic Data for the
Complexes [AuR(CtNC6H4C6H4OCnH2n+1-p)]
Scheme 2
R
n
transitiona
tempb (°C)
∆Hb (kJ/mol)
C6F5
4
C- - -C′
C′- - -N
N- - -I
C- - -C′
C′- - -SA
SA- - -N
N- - -I
C- - -SA
SA- - -N
N- - -I
C- - -SA
SA- - -I
C- - -SA
SA- - -I
C- - -C′
C′- - -N
N- - -I
C- - -SA
SA- - -N
N- - -I
C- - -SA
SA- - -N
N- - -I
C- - -SA
SA- - -I
C- - -SA
SA- - -I
C- - -N
N- - -I
C- - -SA
SA- - -N
N- - -I
98.5
0.2
31.6
0.7
2.0
33.7
0.1
1.0
37.0
0.3
1.0
42.9
2.8
138.7
186.5
86.8
C6F5
C6F5
6
8
99.3
122.6
166.8
70.0
148.8
158.9
75.3
150.5
70.3
133.4
106.1
119.7
168d (dec)
95.4
128.9
166.1
74.6
139.7
148.0
80.8
C6F5
10
12
4
C6F5
41.7
2.6
C6F4Br-o
5.5c
22.2c
C6F4Br-o
C6F4Br-o
6
8
25.9
0.1
1.1
22.6
0.3
0.7
42.3
2.6
35.5
C6F4Br-o
C6F4Br-o
C6F4Br-p
C6F4Br-p
10
12
4
150.6
81.0
147d (dec)
136.8
219.7
106.4
140c
36.6
0.9
25.0
6
195.7
114.1
187.3
196.6
99.4
192.6
100.3
192.7
0.9
3.1
0.4
0.9
32.9
3.7
C6F4Br-p
8
C- - -SA
SA- - -N
N- - -I
C- - -SA
SA- - -I
C- - -SA
SA- - -I
C6F4Br-p
C6F4Br-p
10
12
42.8
4.4
The 19F NMR spectra of the C6F4Br-p compounds show two
somewhat distorted “doublets” flanked by two pseudotriplets
(strictly an AA′XX′ spin system with JAA′ ≈ JXX′).
a C, crystal; S, smectic; N, nematic; I, isotropic liquid. b Data refer
to the second DSC cycle starting from the crystal formed on cooling
the mesophase. Temperature data as peak onset. c Data refer to the
first DSC cycle. d Optical microscopy data.
The 19F NMR spectra of the 4,4′-octafluorobiphenyl com-
pounds show two complex multiplets at ca. -117 and -140
ppm, corresponding to the ortho and the meta fluorine atoms
as reported for similar tetrahydrothiophene complexes.55
Mesogenic Behavior. Mononuclear Compounds. The
complex [Au(C6F5)(CtNC6H4OC10H21-p)] does not display
liquid crystal behavior, but all the gold biphenyl isocyanide
compounds [AuR(CtNC6H4C6H4OCnH2n+1-p)] (R ) C6F5,
C6F4Br-o, C6F4Br-p) are mesomorphic and their optical, thermal,
and thermodynamic data are presented in Table 1. The free
biphenyl isocyanides display nematic (N) and/or smectic A (SA)
phases in the range 40-85 °C.38 Their (perhalophenyl)gold(I)
complexes behave as liquid crystals showing a N phase when
the isocyanide has a short tail (n ) 4), N and SA phases when
the isocyanide has an intermediate tail (n ) 6, 8), and only a
SA phase for longer chains. The SA mesophases present the
typical mielinic and homeotropic textures reorganizing to the
fan-shaped texture at temperatures close to the clearing point
and the focal-conic fan texture on cooling from the nematic or
isotropic phases. The nematic phases show the schlieren texture.
Some of the compounds show crystal-to-crystal transitions
before melting.
The decrease of transition temperatures with increasing length
is small for C6F4Br-p derivatives, greater for those of C6F4Br-
o, and more marked for C6F5 complexes. As a consequence of
this trend, a change is produced in the sequence of melting and
clearing temperatures the order being C6F4Br-p g C6F5 > C6F4-
Br-o when n e 6 and C6F4Br-p > C6F4Br-o > C6F5 for n g 8.
The mononuclear gold(III) isocyanide compounds are ther-
mally unstable, and heating leads to cleavage of the Au-R bond
(R ) C6F5, C6F4Br-o) to give the corresponding halogold(I)
isocyanide derivatives.34,36
Dinuclear Compounds. The mesogenic behavior of [(µ-
4,4′-C6F4C6F4){AuCtN(C6H4)mOCnH2n+1}2] (m ) 1, 2, n )
4, 6, 8, 10, 12) is presented in Table 2. They all display a N
mesophase, identified in optical microscopy by its typical
marbled texture. Some of the compounds show one crystal-
to-crystal transition before melting. All the biphenyl isocyanide
derivatives and the phenyl isocyanide compounds with n e 6
undergo some decomposition upon reaching the clearing point
to the isotropic state, possibly due to their very high transition
temperatures.
The variation in thermal properties is quite regular and can
be summarized for each family as follows: The melting and
clearing temperatures decrease with increasing length of the
alkoxy chain to reach a roughly constant value beyond n ) 8.
The range of SA phase increases, and that of N phase decreases
as the length of the chain increases.
The variation in thermal properties can be summarized as
follows: The clearing temperatures decrease with increasing
length of the alkoxy chain and in the order biphenyl > phenyl.
The same trend is observed for the melting temperatures with

2332 Inorganic Chemistry, Vol. 36, No. 11, 1997
Bayo´n et al.
Table 2. Optical, Thermal, and Thermodynamic Data for the
Complexes [(µ-4,4′-C6F4C6F4){AuCtN(C6H4)mOCnH2n+1-p}2]
m
1
n
transitiona
tempb (°C)
∆Hb (kJ/mol)
4
C- - -N
N- - -I
C- - -C′
C′- - -N
N- - -I
C- - -N
N- - -I
C- - -N
N- - -I
C- - -C′
C′- - -N
N- - -I
C- - -N
N- - -I
C- - -C′
C′- - -N
N- - -I
C- - -N
N- - -I
224.4
50.1
275.0c (dec)
115.4
1
6
5.1
44.9
173.3
254.0c (dec)
193.6
1
1
1
8
10
12
56.4
4.2
51.0
3.6
2.3
45.5
3.1
245.7
149.5
220.8
112.3
152.2
202.9
246.4d
261 (dec)
184.3
35.8
Figure 1. Comparison of the thermal properties of complexes [AuCl-
(CtNC6H4C6H4OCnH2n+1-p)] reported in ref 36 and [Au(C6F4Br-p)-
(CtNC6H4C6H4OCnH2n+1-p)] (Ic).
2
2
4
6
2.6
42.9
211.2
278c (dec)
183.8
factor. Thus the transition temperatures are in the order C6F5
> C6F4Br-o for n e 6 and the opposite for n g 8.
It is also interesting to compare the variation of transition
2
2
2
8
10
12
39.4
42.0
275c (dec)
175.2
C- - -N
N- - -I
C- - -C′
C′- - -N
N- - -I
245c (dec)
93.4
temperatures of these complexes [AuR(CtNC6H4C6H4OCnH2n+1
-
12.0
35.9
p)] with that of the previously reported compounds [AuX-
(CtNC6H4C6H4OCnH2n+1-p)] (X ) halogen).36 The thermal
properties of both kinds of complexes are compared in Figure
1 for R ) C6F4Br-p and X ) Cl. It can be seen that the
perhalophenyl group produces lower transition temperatures,
shorter mesogenic ranges, and an enhancement of nematic
phases, according to the expected lower lateral intermolecular
interactions as consequence of their greater molecular width.
Thus it is not unexpected that when the conjugated rigid core
is reduced, as in [Au(C6F5)(CtNC6H4OCnH2n+1-p)], the me-
sogenic properties are lost.
In the complexes [(µ-4,4′-C6F4C6F4){AuCtN(C6H4)m-
OCnH2n+1}2} (m ) 1, 2; n ) 4, 6, 8, 10, 12) the rather high
transition temperatures found suggest good intermolecular
interactions. Only the N phase is observed. It is well-known
that the steric and electronic repulsions between the fluorine
atoms produce large twist angles (about 53°) between the two
rings of the octafluorobiphenyl group, as found crystallographi-
cally for nickel complexes.59 This must necessarily reduce the
π-conjugation between the two halves of our dinuclear gold
complexes to a very small value. In other words, as far as
polarizability and other properties associated with π-conjugation
are concerned, these gold complexes can be assimilated to two
monomeric molecules linked head-to-head, the dimer having
no net dipolar moment but possessing a complex multipolar
structure. The intermolecular interactions between these large
multipolar molecules is strong, as suggested by the high
transition temperatures. These high melting temperatures and
the nonplanar nature of the octafluorobiphenyl moiety (hindering
the adoption of a planar shape for a more efficient stacking of
molecules) will both cooperate to create the appearance of the
entropically favored nematic phase.
160.9
240c (dec)
a C, crystal; S, smectic; N, nematic; I, isotropic liquid. b Data referr
to the second DSC cycle starting from the crystal formed on cooling
the mesophase. Temperature data as peak onset. c Optical microscopy
data. d Data referr to the first DSC cycle.
one exception, the gold(I) (octyloxy)phenyl isocyanide com-
pound whose melting point is higher than that of the hexyloxy
derivative.
Similarly to the mononuclear perhalophenyl derivatives
discussed above, the thermal treatment of dinuclear (octafluo-
robiphenyl)gold(III) complexes led to cleavage of the gold-
octafluorobiphenyl bonds to give the corresponding halogold(I)
isocyanide complexes.
Discussion
The simplest way to look at the rodlike molecules [AuR-
(CtNC6H4C6H4OCnH2n+1-p)] (R ) C6F4Br-o, C6F4Br-p) is to
consider them as formal derivatives of [Au(C6F5)(CtNC6H4C6H4-
OCnH2n+1)] by substitution of a F by a Br atom in the lateral or
terminal position, which will determine the magnitude of
intermolecular electrostatic interactions.
Irrespective of its position, the introduction of a Br substituent
leads to higher values for the molecular polarizability as Br is
more polarizable than F,57,58 increasing intermolecular interac-
tions and leading to higher transition temperatures. On the other
hand, a Br atom in the para position produces only a small
increase in the total length of the molecule, while in the ortho
position it causes a noticeable increase in the width of the
molecule, reducing the intermolecular attractions and leading
to lower transition temperatures. Thus, melting and clearing
temperatures for the C6F4Br-p compounds should be higher than
those for the C6F5 and for the C6F4Br-o derivatives, as observed.
Similarly, the polarizability of the C6F4Br-o group is higher
than that of the C6F5 group, but the width of the former is higher
than that of the later. This helps one to understand the fact
that the transition temperatures are greater for C6F4Br-o than
for C6F5, except for low lengths of the alkoxy chain, where the
width of the perhalophenyl group seems to be the determining
It can be seen that these dinuclear complexes produce nematic
phases at temperatures where the monomeric compounds display
SA phases (compare for instance the C6F4Br-p derivative for n
) 12). The accessibility of a N, involving the slip of molecules
with mixing of aromatic and aliphatic regions, must depend on
the energy difference between that disordered arrangement and
the more ordered smectic arrangement with discrimination of
aromatic and aliphatic regions. As suggested in Figure 2, for
a dipolar molecule the aromatic interactions favor the adoption
of smectic arrangements (a), and this interaction must be
(57) Seed, A. J.; Toyne, K. J.; Goodby, J. W. J. Mater. Chem. 1995, 5,
2201.
(58) Handbook of Chemistry and Physics; Lide, D. R., Ed.; CRC Press:
Boca Rato´n, FL, 1992; pp 10-194.
(59) Craig Sturge, K.; Hunter, A. D.; McDonald, R.; Santarsiero, B. D.
Organometallics 1992, 11, 3056.

(Perhalophenyl)gold(I) Isocyanide Complexes
Inorganic Chemistry, Vol. 36, No. 11, 1997 2333
Br-o)(tht)], δ1 -116.19 (dd, 3J1,2 ) 30.5 Hz, 5J1,4 ) 11.9 Hz, Fortho), δ2
-157.08 (ddd, 3J1,2 ) 30.5 Hz, 3J2,3 ) 19.5 Hz, 4J2,4 ) 1.4 Hz, Fmeta),
3
3
δ3 -157.80 (dd, J2,3 ) 19.5 Hz, J3,4 ) 21.2 Hz, Fpara), δ4 -127.10
3
5
4
(ddd, J3,4 ) 21.2 Hz, J1,4 ) 11.9 Hz, J2,4 ) 1.4 Hz, Fortho to Br);
[Au(C6F4Br-p)(tht)], δ1 -115.50 (Fortho), δ2 -135.30 (Fmeta), AA′XX′
spin system (3J1,2 + J1,2′ ) 18.3 Hz, J1,1′ + J2,2′ ) 10.0 Hz, J1,2
-
5
4
4
3
5J1,2′ ) 42.5 Hz).
All compounds [AuR(CtN(C6H4)mOCnH2n+1-p)] (m ) 1, n ) 10,
R ) C6F5; m ) 2, n ) 4, 6, 8, 10, 12, R ) C6F5, C6F4Br-o, C6F4Br-p),
[(µ-4,4′-C6F4C6F4){Au(CtN(C6H4)mOCnH2n+1-p}2] (m ) 1, 2; n ) 4,
6, 8, 10, 12), [Au(R)I2(CtNC6H4C6H4OCnH2n+1-p)] (R ) C6F4Br-o, n
) 10; R ) C6F5, n ) 8) and [(µ-4,4′-C6F4C6F4){AuX2(CtN(C6H4C6H4-
OC8H17-p)}2] (X ) I, Br) were prepared as reported for (pentafluo-
rophenyl)gold(I) and -gold(III) isocyanide complexes,54,55 with some
modifications. Only examples are described as the syntheses were
similar for the rest of the complexes. Yields, IR, and analytical data
are given for all the gold isocyanide complexes.
Preparation of [Au(C6F4Br-o)(CtNC6H4C6H4OCnH2n+1-p)]. n )
4. To a solution of [Au(C6F4Br-o)(tht)] (0.100 g, 0.195 mmol) in 40
mL of diethyl ether was added CtNC6H4C6H4OC4H9-p (0.049 g, 0.195
mmol). After the solution was stirred for 1 h, the solvent was removed
on a rotary evaporator and the white solid obtained was recrystallized
from dichloromethane/hexane (0.095 g, 72% yield). 1H NMR
5
(CDCl3): δ1 7.58, δ2 7.68, AA′XX′ spin system (3J1,2 + J1,2′ ) 8.6
5
Hz), δ3 7.52, δ4 7.00, AA′XX′ spin system (3J3,4 + J3,4′ ) 8.8 Hz),
4.01 (t, J ) 6.5 Hz, O-CH2), 1.86-0.88 (m, 7H, alkyl chain). 19F
NMR (CDCl3): δ1 -116.19 (dd, 3J1,2 ) 29.3 Hz, 5J1,4 ) 11.8 Hz, Fortho),
3
3
δ2 -157.08 (dd, J1,2 ) 29.3 Hz, J2,3 ) 19.9 Hz, Fmeta), δ3 -156.82
3
3
3
(dd, J2,3 ) 19.9 Hz, J3,4 ) 19.9 Hz, Fpara), δ4 -127.54 (dd, J3,4
)
Figure 2. A simple model showing different positions of two molecules
as they slip with respect to each other for a molecule with a dipolar
rigid core (a, b) or a molecule with a multipolar symmetric rigid core
(c, d, e).
5
19.9 Hz, J1,4 ) 11.8 Hz, Fortho to Br). IR [ν(CtN)]: (CH2Cl2) 2214,
(KBr) 2214. Anal. Calcd for C23H17AuBrF4NO: C, 40.88; H, 2.53;
N, 2.07. Found: C, 41.12; H, 2.50; N, 2.47.
Yields, IR, and analytical data are as follows:
overcome to reach the mixing of aromatic and aliphatic regions
(b) characteristic of nematic phases. For the symmetric dimers,
however, the best multipole-multipole interactions are not those
represented in (c), but probably those in (d) which already
involve some mixing of aromatic and aliphatic regions. Thus,
the slip with mixing of the regions (e) giving rise to a nematic
phase must become thermally more easily accessible, and it is
the only one observed above the melting point.
n ) 6. Yield: 60%. IR [ν(CtN)]: (CH2Cl2) 2214, (KBr) 2213.
Anal. Calcd for C25H21AuBrF4NO: C, 42.67; H, 3.01; N, 1.99.
Found: C, 43.01; H, 3.01; N, 2.38.
n ) 8. Yield: 70%. IR [ν(CtN)]: (CH2Cl2) 2214, (KBr) 2219.
Anal. Calcd for C27H25AuBrF4NO: C, 44.28; H, 3.44; N, 1.91.
Found: C, 44.67; H, 3.39; N, 2.18.
n ) 10. Yield: 67%. IR [ν(CtN)]: (CH2Cl2) 2214, (KBr) 2218.
Anal. Calcd for C29H29AuBrF4NO: C, 45.80; H, 3.84; N, 1.84.
Found: C, 45.46; H, 3.88; N, 1.98.
Conclusions
n ) 12. Yield: 50%. IR [ν(CtN)]: (CH2Cl2) 2214, (KBr) 2218.
Anal. Calcd for C31H33AuBrF4NO: C, 47.22; H, 4.21; N, 1.77.
Found: C, 47.09; H, 3.82; N, 2.49.
The use of perhaloaryl rings, which give quite stable Au-C
bonds, allows the synthesis of metal-containing liquid crystals
with only M-C σ-bonds. In spite of the bulkiness of some of
these groups, large ranges of N or SA phases are obtained. The
mesogenic behavior can be roughly explained using simple
arguments of polarization and polarizability of the species
involved. The dominance of nematic behavior in symmetric
dinuclear complexes is particularly interesting.
[Au(C6F5)(CtNC6H4C6H4OCnH2n+1-p)]. n ) 4. Yield: 77%. 1H
NMR (CDCl3): δ1 7.58, δ2 7.68, AA′XX′ spin system (3J1,2 + 5J1,2′
)
5
8.6 Hz), δ3 7.52, δ4 7.00, AA′XX′ spin system (3J3,4 + J3,4′ ) 8.8
Hz), 4.01 (t, J ) 6.5 Hz, O-CH2), 1.86-0.88 (m, 7H, alkyl chain). 19
F
NMR (CDCl3): δ1 -116.47 (m, Fortho), δ2 -162.72 (m, Fmeta), δ3
-157.84 (t, J2,3 ) 19.8 Hz, Fpara). IR [ν(CtN)]: (CH2Cl2) 2216, (KBr)
2210. Anal. Calcd for C23H17AuF5NO: C, 44.87; H, 2.76; N, 2.28.
Found: C, 44.65; H, 2.77; N, 2.34.
Experimental Section
Yields, IR, and analytical data are as follows:
n ) 6. Yield: 88%. IR [ν(CtN)]: (CH2Cl2) 2215, (KBr) 2211.
Anal. Calcd for C25H21AuF5NO: C, 46.66; H, 3.27; N, 2.18. Found:
C, 46.30; H, 3.18; N, 2.24.
n ) 8. Yield: 87%. IR [ν(CtN)]: (CH2Cl2) 2217, (KBr) 2225.
Anal. Calcd for C27H25AuF5NO: C, 48.29; H, 3.72; N, 2.09. Found:
C, 48.16; H, 3.65; N, 2.14.
n ) 10. Yield: 72%. IR [ν(CtN)]: (CH2Cl2) 2215, (KBr) 2225.
Anal. Calcd for C29H29AuF5NO: C, 49.78; H, 4.15; N, 2.00. Found:
C, 49.71; H, 4.03; N, 1.74.
Combustion analyses were completed with a Perkin-Elmer 2400
microanalyzer. IR spectra (cm-1) were recorded on a Perkin-Elmer
FT 1720X instrument, and 1H NMR spectra, on a Bruker AC 300
instrument in CDCl3. Microscopy studies were carried out using a Leitz
microscope provided with a hot stage and polarizers at a heating rate
of approximately 10 °C min-1. For differential scanning calorimetry
(DSC) a Perkin-Elmer DSC7 instrument was used, which was calibrated
with water and indium; the scanning rate was 10 °C min-1, the samples
were sealed in aluminum capsules in the air, and the holder atmosphere
was dry nitrogen.
n ) 12. Yield: 79%. IR [ν(CtN)]: (CH2Cl2) 2215, (KBr) 2225.
Anal. Calcd for C31H33AuF5NO: C, 51.17; H, 4.54; N, 1.93. Found:
C, 51.29; H, 4.51; N, 1.91.
Literature methods were used to prepare [CtNC6H4C6H4OCnH2n+1
-
p],36 [CtNC6H4OCnH2n+1-p],34 and [(µ-4,4′-C6F4C6F4){Au(tht)}2] (tht
) tetrahydrothiophene).55 [Au(R)(tht)] (R ) C6F4Br-o, C6F4Br-p) were
prepared similarly to [Au(C6F5)(tht)],60 using the corresponding bromo
derivatives C6F4Br2-o and C6F4Br2-p. 19F NMR (CDCl3): [Au(C6F4-
[Au(C6F5)(CtNC6H4OC10H21-p)]. Yield: 79%. 1H NMR (CDCl3):
5
δ1 7.46, δ2 6.96, AA′XX′ spin system (3J1,2 + J1,2′ ) 8.9 Hz), 4.0 (t,
J ) 6.5 Hz, O-CH2), 1.81-0.88 (m, 19H, alkyl chain). 19F NMR
(CDCl3): δ1 -116.5 (m, Fortho), δ2 -162.84 (m, Fmeta), δ3 -158.0 (t,
J2,3 ) 20 Hz, Fpara). IR [ν(CtN)]: (CH2Cl2) 2218, (KBr) 2226. Anal.
(60) Uso´n, R.; Laguna, A.; Laguna, M. Inorg. Synth. 1989, 26, 85.

2334 Inorganic Chemistry, Vol. 36, No. 11, 1997
Bayo´n et al.
Calcd for C23H25AuF5NO: C, 44.35; H, 4.01; N, 2.25. Found: C,
44.21; H, 3.98; N, 2.36. Optical data: C-I, 64 °C.
n ) 8. Yield: 65%. IR [ν(CtN)]: (CH2Cl2) 2218, (KBr) 2211.
Anal. Calcd for C42H42Au2F8N2O2: C, 43.76; H, 3.67; N, 2.43.
Found: C, 43.80; H, 3.65; N, 2.63.
[Au(C6F4Br-p)(CtNC6H4C6H4OCnH2n+1-p)]. n ) 4. Yield: 77%.
1H NMR (CDCl3): δ1 7.58, δ2 7.68, AA′XX′ spin system (3J1,2 + 5J1,2′
n ) 10. Yield: 81%. IR [ν(CtN)]: (CH2Cl2) 2217, (KBr) 2208.
Anal. Calcd for C46H50Au2F8N2O2: C, 45.71; H, 4.17; N, 2.32.
Found: C, 45.68; H, 4.18; N, 2.48.
5
) 8.6 Hz), δ3 7.52, δ4 7.00, AA′XX′ spin system (3J3,4 + J3,4′ ) 8.8
Hz), 4.01 (t, J ) 6.5 Hz, O-CH2), 1.86-0.88 (m, 7H, alkyl chain).
19F NMR (CDCl3): δ1 -115.39, δ2 -135.27, AA′XX′ spin system (3J1,2
+ 5J1,2′ ) 17.4 Hz, 4J1,1′ + 4J2,2′ ) 9.5 Hz, 3J1,2 - 5J1,2′ ) 42.2 Hz). IR
[ν(CtN)]: (CH2Cl2) 2216, (KBr) 2220. Anal. Calcd for
C23H17AuBrF4NO: C, 40.88; H, 2.53; N, 2.07. Found: C, 41.22; H,
2.50; N, 2.47.
n ) 12. Yield: 80%. IR [ν(CtN)]: (CH2Cl2) 2214, (KBr) 2218.
Anal. Calcd for C50H58Au2F8N2O2: C, 47.48; H, 4.62; N, 2.22.
Found: C, 47.27; H, 4.42; N, 2.15.
Preparation of [Au(C6F5)I2(CtNC6H4C6H4OC8H17-p)]. To a
solution of [Au(C6F5)(CtNC6H4C6H4OC8H17-p)] (0.100 g, 0.150 mmol)
in 40 mL of diethyl ether was added iodine (0.050 g, 0.200 mmol).
After the solution was stirred for 90 min the solvent was removed on
a rotary evaporator and the white solid obtained was recrystallized from
dichloromethane/hexane (0.027 g, 40% yield). Anal. Calcd for
AuC27F5H25I2NO: C, 35.03; H, 2.70; N, 1.51. Found: C, 35.22; H,
Yields, IR, and analytical data are as follows:
n ) 6. Yield: 74%. IR [ν(CtN)]: (CH2Cl2) 2216, (KBr) 2207.
Anal. Calcd for C25H21AuBrF4NO: C, 42.67; H, 3.01; N, 1.99.
Found: C, 42.44; H, 2.91; N, 1.88.
n ) 8. Yield: 70%. IR [ν(CtN)]: (CH2Cl2) 2217, (KBr) 2207.
Anal. Calcd for C27H25AuBrF4NO: C, 44.28; H, 3.44; N, 1.91.
Found: C, 44.05; H, 3.25; N, 2.42.
n ) 10. Yield: 74%. IR [ν(CtN)]: (CH2Cl2) 2216, (KBr) 2224.
Anal. Calcd for C29H29AuBrF4NO: C, 45.80; H, 3.84; N, 1.84.
Found: C, 45.65; H, 3.70; N, 1.76.
n ) 12. Yield: 85%. IR [ν(CtN)]: (CH2Cl2) 2216, (KBr) 2224.
Anal. Calcd for C31H33AuBrF4NO: C, 47.22; H, 4.21; N, 1.77.
Found: C, 47.06; H, 3.96; N, 1.72.
2.62; N, 1.47. IR [ν(CtN)]: (CH2Cl2): 2250 cm-1
.
1H NMR
5
(CDCl3): δ1 7.68, δ2 7.74, AA′XX′ spin system (3J1,2 + J1,2′ ) 8.8
5
Hz), δ3 7.53, δ4 7.00, AA′XX′ spin system (3J3,4 + J3,4′ ) 8.8 Hz),
4.00 (t, J ) 6.6 Hz, O-CH2), 1.82-0.88 (m, 15H, alkyl chain). 19F
NMR (CDCl3): δ1 -118.59 (m, Fortho), δ2 -156.16 (t, J ) 19.7 Hz,
Fpara), δ3 -162.02 (m, Fmeta).
[Au(C6F4-Br-o)I2(CtNC6H4C6H4OC10H21-p)] was similarly pre-
pared. Anal. Calcd for AuBrC29F4H28I2NO: C, 34.34; H, 2.88; N,
1.38. Found: C, 34.31; H, 2.75; N, 1.67. IR [ν(CtN)]: (CH2Cl2):
Preparation of [(µ-4,4′-C6F4C6F4){Au(CtNC6H4C6H4OCnH2n+1
-
p)}2]. n ) 4. To a solution of [(µ-4,4′-C6F4C6F4){Au(tht)}2] (0.100
g, 0.115 mmol) in 40 mL of diethyl ether was added CtNC6H4C6H4-
OC4H9-p (0.077 g, 0.26 mmol). After the solution was stirred for 1 h,
the solvent was removed on a rotary evaporator and the white solid
obtained was recrystallized from dichloromethane/hexane (0.140 g, 89%
yield). 1H NMR (CDCl3): δ1 7.59, δ2 7.68, AA′XX′ spin system (3J1,2
+ 5J1,2′ ) 8.5 Hz), δ3 7.52, δ4 7.00, AA′XX′ spin system (3J3,4 + 5J3,4′
) 8.8 Hz), 4.01 (t, J ) 6.3 Hz, O-CH2), 1.83-0.80 (m, 19H, alkyl
chain). 19F NMR (CDCl3): -117.70 (Fortho), -140.50 (Fmeta). IR
[ν(CtN)]: (CH2Cl2) 2216, (KBr) 2210. Anal. Calcd for
C46H34Au2F8N2O2: C, 46.32; H, 2.87; N, 2.35. Found: C, 45.89; H,
2.92; N, 2.20.
2245 cm-1 1H NMR (CDCl3): δ1 7.68, δ2 7.73, AA′XX′ spin system
.
(3J1,2 + 5J1,2′ ) 8.7 Hz), δ3 7.53, δ4 7.00, AA′XX′ spin system (3J3,4
+
5J3,4′ ) 8.7 Hz), 4.00 (t, J ) 6.5 Hz, O-CH2), 1.83-0.87 (m, 15H,
3
alkyl chain). 19F NMR (CDCl3): δ1 -117.16 (dd, J1,2 ) 24.3 Hz,
3
3
5J1,4 ) 8.2 Hz, Fortho), δ2 -155.27 (dd, J1,2 ) 24.3 Hz, J2,3 ) 19.9
3
3
Hz, Fmeta), δ3 -155.53 (dd, J2,3 ) 19.9 Hz, J3,4 ) 19.9 Hz, Fpara), δ4
-128.20 (dd, J3,4 ) 19.9 Hz, J1,4 ) 8.2 Hz, Fortho to Br).
3
5
Preparation of [(µ-4,4′-C6F4C6F4){AuI2(CtNC6H4C6H4OC8H17-
p)}2]. To a solution of [(µ-4,4′-C6F4C6F4){Au(CtNC6H4C6H4OC8H17-
p)}2] (0.080 g, 0.061 mmol) in 50 mL of dichloromethane was added
iodine (0.031 g, 0.123 mmol). After the solution was stirred for 90
min, the solvent was removed on a rotary evaporator and the red solid
obtained was recrystallized from dichloromethane/hexane (0.033 g, 30%
yield). Anal. Calcd for Au2C54F8H50I4N2O2: C, 35.78; H, 2.78; N,
1.55. Found: C, 35.69; H, 2.74; N, 1.52. IR [ν(CtN)]: (KBr) 2242
Yields, IR, and analytical data are as follows:
n ) 6. Yield: 62%. IR [ν(CtN)]: (CH2Cl2) 2214, (KBr) 2206.
Anal. Calcd for C50H42Au2F8N2O2: C, 48.09; H, 3.39; N, 2.56.
Found: C, 47.81; H, 3.15; N, 2.36.
n ) 8. Yield: 77%. IR [ν(CtN)]: (CH2Cl2) 2214, (KBr) 2219.
Anal. Calcd for C54H50Au2F8N2O2: C, 49.70; H, 3.86; N, 2.15.
Found: C, 49.59; H, 3.73; N, 2.21.
n ) 10. Yield: 76%. IR [ν(CtN)]: (CH2Cl2) 2215, (KBr) 2210.
Anal. Calcd for C58H58Au2F8N2O2: C, 51.18; H, 4.29; N, 2.06.
Found: C, 51.03; H, 4.23; N, 1.94.
n ) 12. Yield: 75%. IR [ν(CtN)]: (CH2Cl2) 2216, (KBr) 2211.
Anal. Calcd for C62H66Au2F8N2O2: C, 52.55; H, 4.69; N, 1.98.
Found: C, 52.37; H, 4.14; N, 1.41.
Yields, IR, and analytical data for [(µ-4,4′-C6F4C6F4){Au(CtNC6H4-
OCnH2n+1-p)}2] are as follows:
n ) 4. Yield: 72%. IR [ν(CtN)]: (CH2Cl2) 2218, (KBr) 2212.
Anal. Calcd for C34H26Au2F8N2O2: C, 39.25; H, 2.52; N, 2.69.
Found: C, 39.25; H, 2.56; N, 2.75.
n ) 6. Yield: 78%. IR [ν(CtN)]: (CH2Cl2) 2218, (KBr) 2212.
Anal. Calcd for C38H34Au2F8N2O2: C, 41.62; H, 3.13; N, 2.56.
Found: C, 41.56; H, 3.15; N, 2.53.
cm-1 1H NMR (CDCl3): δ1 7.76, δ2 7.71, AA′XX′ spin system (3J1,2
.
+ 5J1,2′ ) 8.9 Hz), δ3 7.55, δ4 7.02, AA′XX′ spin system (3J3,4 + 5J3,4′
) 8.8 Hz), 4.01 (t, J ) 6.5 Hz, O-CH2), 1.84-0.87 (m, 15H, alkyl
chain). 19F NMR (CDCl3): -119.31 (Fortho), -139.00 (Fmeta).
[(µ-4,4′-C6F4C6F4){AuBr2(CtNC6H4C6H4OC8H17-p)}2] was simi-
larly prepared. Anal. Calcd for Au2Br4C54F8H50N2O2: C, 39.92; H,
3.10; N, 1.72. Found: C, 40.52; H, 2.99; N, 3.27. IR [ν(CtN)]: (KBr)
2251 cm-1 1H NMR (CDCl3): δ1 7.75, δ2 7.70, AA′XX′ spin system
.
(3J1,2 + 5J1,2′ ) 8.9 Hz), δ3 7.55, δ4 7.01, AA′XX′ spin system (3J3,4
+
5J3,4′ ) 8.8 Hz), 4.01 (t, J ) 6.5 Hz, O-CH2), 1.86-0.86 (m, 15H,
alkyl chain). 19F NMR (CDCl3): -123.27 (Fortho), -138.38 (Fmeta).
Acknowledgment. We are indebted to the Comisio´n Inter-
ministerial de Ciencia y Tecnolog´ıa for financial support (Project
MAT93-0329 and MAT96-0329).
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