Gold(II) phthalocyanine revisited: Synthesis and spectroscopic properties of gold(III) phthalocyanine and an unprecedented ring-contracted phthalocyanine analogue

Article abstract of DOI:10.1002/chem.201201701

In 1965, gold(II) phthalocyanine (AuPc, 1) was described to be synthesized from unsubstituted 1,3-diiminoisoindoline and gold powder or AuBr. Compound 1 has been regarded as a rare example of a paramagnetic gold(II) complex. However, its chemistry, especially the oxidation state of the central gold ion, has not been previously explored due to the inherent insolubility of 1 caused by its unsubstituted structure. In our attempt to synthesize soluble AuPcs by using 5,6-di-substituted 1,3-diiminoisoindolines, gold(III) phthalocyanine chloride (3) and a gold(III) complex of an unprecedented ring-contracted phthalocyanine analogue ([18]tribenzo-pentaaza-triphyrin(4,1,1), 4) were isolated. With this discrepant result from the original literature in hand, a reinvestigation of the original AuPc synthesis by using unsubstituted 1,3-diiminoisoindoline and various gold salts (including gold powder and AuBr) was performed, finding that only unsubstituted analogues of 3 and 4 or free-base phthalocyanine were obtained. Copyright

Full text of DOI:10.1002/chem.201201701

FULL PAPER
DOI: 10.1002/chem.201201701
Gold(II) Phthalocyanine Revisited: Synthesis and Spectroscopic Properties of
GoldACHTUNGTRENNUNG(III) Phthalocyanine and an Unprecedented Ring-Contracted
Phthalocyanine Analogue
Edwin W. Y. Wong,[a] Akito Miura,[b] Mathew D. Wright,[a] Qi He,[a] Charles J. Walsby,[a]
Soji Shimizu,*[b] Nagao Kobayashi,*[b] and Daniel B. Leznoff*[a]
Abstract: In 1965, gold(II) phthalocya-
nine (AuPc, 1) was described to be syn-
thesized from unsubstituted 1,3-diimi-
noisoindoline and gold powder or
AuBr. Compound 1 has been regarded
as a rare example of a paramagnetic
gold(II) complex. However, its chemis-
try, especially the oxidation state of the
central gold ion, has not been previous-
ly explored due to the inherent insolu-
bility of 1 caused by its unsubstituted
structure. In our attempt to synthesize
soluble AuPcs by using 5,6-di-substitut-
ed 1,3-diiminoisoindolines, gold(III)
phthalocyanine chloride (3) and a gold-
(III) complex of an unprecedented
ring-contracted phthalocyanine ana-
logue ([18]tribenzo-pentaaza-triphyrin-
ACHTUNGTRENN(UNG 4,1,1), 4) were isolated. With this dis-
G
crepant result from the original litera-
ture in hand, a reinvestigation of the
original AuPc synthesis by using unsub-
stituted 1,3-diiminoisoindoline and var-
ious gold salts (including gold powder
and AuBr) was performed, finding that
only unsubstituted analogues of 3 and
4 or free-base phthalocyanine were ob-
tained. No gold(II)-containing species
could be isolated.
AHCTUNGTRENNUNG
Keywords: aromaticity
·
gold
·
phthalocyanine · UV/Vis spectro-
scopy · triphyrin
Introduction
Gold is most commonly
found as the neutral metal or in
its +1 (d10) or +3 (d8) oxida-
tion states. This observation can
be rationalized by the fact that
as a third-row transition metal,
gold(II) (d9) has a large crystal-
Metallophthalocyanines (MPcs) are important functional
molecular materials that have found uses in a wide range of
applications, such as pigments, microelectronics, digital-data
storage, xerography, catalysis, and photodynamic cancer
therapy.[1,2] There has been a MPc complex reported for
every transition metal,[2,3] but in spite of their importance,
some MPc complexes have received little attention. For ex-
ample, gold phthalocyanine (AuPc, 1; Scheme 1) reported in
1965[4] is the only known instance of a gold Pc and is also a
rare example of a paramagnetic gold(II) complex.[5] Un-
fortunately, the reported data for 1 was limited to UV/Vis
absorption and EPR spectra.[4] Any further characterization
or studies on the reactivity of 1 has not been described in
the literature probably due to its very poor solubility, which
is typical for unsubstituted MPc compounds.
field splitting. Hence, in
a
square-planar or Jahn–Teller
distorted octahedral coordina-
tion geometry, as can be gener-
ally seen for MPcs, the un-
Scheme 1. Putative gold phtha-
locyanine 1.
paired electron is easily ionized, because it occupies a high
energy dx2ꢀy2 orbital. Thus, paramagnetic gold(II) species
tend to disproportionate into gold(I) and goldACTHNUTRGNEUNG
(III) species.[5]
Among known examples of gold(II) species, paramagnetic
gold(II) metal centers are normally stabilized by ligand-sup-
ported dimerization to form gold–gold bonds resulting in di-
4+
[a] E. W. Y. Wong, M. D. Wright, Q. He, Prof. C. J. Walsby,
Prof. D. B. Leznoff
amagnetic complexes with
a
Au2
core, such as in
[IAu(CH2PMe2CH2)2AuI] and [Au2(CH2PPh2CH2)-[S2CN-
(CH2Ph)2]Br2].[6] Mononuclear complexes containing formal
gold(II) centers, such as [Au([9]aneS3)2](BF4)2,
[Au([9]aneS2)2](BF4)2, and (nBu4N)2[Au(mnt)2] (mnt=male-
Department of Chemistry, Simon Fraser University
8888 University Drive, Burnaby, BC V5A 156 (Canada)
Fax : (+1)778-782-3765
AHCTUNGTRENNUNG
ACHTUNGTRENNUNG
G
ACHTUNGTRENNUNG
E-mail: dleznoff@sfu.ca
onitriledithiolate)[7] have been determined to contain non-
innocent ligands, which introduce uncertainty in the assign-
ment of the gold oxidation state. Gold complexes of por-
phyrins, which are closely related to Pcs, are obtained as
[b] A. Miura, Dr. S. Shimizu, Prof. N. Kobayashi
Department of Chemistry, Graduate School of Science
Tohoku University, Aoba-ku, Sendai 980-8578 (Japan)
Fax : (+81)22-795-7728
E-mail: ssoji@m.tohoku.ac.jp
goldACTHUNRTGNEUNG(III) complexes and can be chemically or electrochemi-
nagaok@m.tohoku.ac.jp
cally reduced to putative gold(II) species in solution (but
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/chem.201201701.
were not isolated).[8]
Chem. Eur. J. 2012, 00, 0 – 0
ꢀ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
&
1
&
ÞÞ
These are not the final page numbers!

With these points in mind, we set out to synthesize a
series of more soluble AuPc analogues to study the spectro-
scopic properties, electronic structure, and oxidation state of
the central gold ions and compare them with the prototypi-
cal putative gold(II) complex 1. Unexpected results during
the pursuit of the AuPc analogues also led to the re-exami-
nation of 1 by using modern analytical techniques.
Results and Discussion
Synthesis and characterization: 5,6-Disubstituted 1,3-diimi-
noisoindolines with p-tert-butylphenyl (2a) and p-tert-butyl-
phenyloxy (2b) groups were utilized to target soluble gold
phthalocyanines. As a source of gold, either gold(I) chloride
(AuCl) or potassium tetrachloroaurateACTHNUTRGNEG(NU III) ([KAuCl4]) was
used. A condensation reaction of a 1,3-diiminoisoindoline
and a gold salt in 1-chloronaphthalene at 2008C gave a mix-
ture of green and blue compounds (3 and 4, respectively;
Scheme 2), which could be easily isolated by silica-gel
column chromatography.[9]
Figure 1. X-ray crystal structure of 3a, top view (top) and side view
(bottom). The thermal ellipsoids were scaled to the 50% probability
level. Hydrogen atoms and one of the disordered chlorine atoms were
omitted for clarity in both views.
Scheme 2. Synthesis of 3 and 4 and axial ligand-exchange reaction with
phenol.
ꢀ
teraction. Similarly, long axial Au Cl bonds are known for
The high-resolution electrospray ionization mass spec-
trometry (HR-ESI-MS) analysis of 3 exhibited molecular-
ion peaks and distribution patterns corresponding to a
phthalocyanine with a gold center (3a: m/z=1765.8641,
calcd for C112H112N8Au 1765.8670 [M+ꢀCl]; 3b: m/z=
1893.8237, calcd for C112H112N8O8Au 1893.8263 [M+ꢀCl]),
whereas the HR-ESI-MS of the blue compounds 4 exhibited
peaks corresponding to a phthalocyanine with a gold and an
extra nitrogen atom (4a: m/z=1802.8609, calcd for
gold–porphyrin complexes.[11] Given the normally dianionic
nature of the Pc ligand and the anionic chloride ligand, 3 is
clearly an AuIII-containing MPc—indeed, it represents the
first structurally characterized example of a gold phthalocya-
nine.
The structure of 4a exhibits a so-called triphyrin-like
structure with a square-planar gold
three isoindole units linked by two meso-nitrogen atoms and
unique N C N N bonds: the N N bond lengths of 1.408(7)
and 1.421(6) ꢁ are in the range of a single-bond distance
(Figure 2).[12] This linkage would be plausibly formed by re-
acting half of a 1,3-diiminoisoindole unit, which results in
the regeneration of a cyano group. According to the conven-
tional nomenclature of porphyrinoids,[13] the macrocycle in 4
ACHTUNGERTN(NUNG III) center comprising
ꢀ ꢀ ꢀ
ꢀ
C
112H112N9AuNa 1802.8598 [M+ +Na]; 4b: m/z=1930.8216,
calcd for C112H112N9O8AuNa 1930.8192 [M+ +Na]).
The structures of two representative complexes of 3 and 4
were unambiguously elucidated by single-crystal X-ray anal-
ysis. In the crystal structure of 3a, the central gold ion is
bound in a square-pyramidal fashion by four nitrogen atoms
of the Pc ligand and a chlorine atom (Figure 1).[10] The axial
chloride ligand is disordered into two positions with
can be referred to as [18]tribenzo-pentaaza-triphyrinACHTUNGTRENNUNG(4,1,1).
In the unit cell, two triphyrin molecules form a slipped
stacking dimer with an interplanar separation of approxi-
mately 3.3 ꢁ. This preferential formation of a p–p stacking
dimer in the solid state is reflected in the tendency of 4 to
ꢀ
0.65:0.35 occupancies; the long Au Cl bond length of
ꢀ
3.12(9) ꢁ on average is indicative of a more ionic Au Cl in-
&
2
&
www.chemeurj.org
ꢀ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 0000, 00, 0 – 0
ÝÝ
These are not the final page numbers!

Gold(II) Phthalocyanine Revisited
FULL PAPER
columnar array of 4a observed in the solid state. The broad
proton signals of 4a were improved when measured in
[D6]benzene exhibiting assignable peak patterns, whereas
1
the H NMR spectrum of 4b in [D6]benzene showed severe
overlaps of peaks arising from both aggregation and the low
molecular symmetry of 4.
UV/Vis absorption and MCD spectroscopies: The UV/Vis
absorption spectra of 3a and 3b in CHCl3 exhibited a sharp
Q band absorption at l=714 and 696 nm (Figure 3a), re-
Figure 2. X-ray crystal structure of 4a, top view (top) and side view
(bottom). The thermal ellipsoids were scaled to the 50% probability
level. Hydrogen atoms were omitted for clarity in both views.
Figure 3. UV/Vis absorption (bottom) and MCD (top) spectra of a) 3a
(solid line) and 3b (dotted line) in CHCl3; b) 4a (solid line) and 4b
(dotted line) in toluene.
aggregate in solution at the concentrations used for
1H NMR measurements (see below).
In the H NMR spectra of 3, a singlet signal of a-benzo
1
protons (3a: d=9.15 ppm; 3b: d=8.67 ppm) and two dou-
blet signals due to the p-tert-butylphenyl substituents (3a:
d=7.42 and 7.36 ppm; 3b: 7.40 and 7.18 ppm) are observed
in the down-field region. These 1H NMR spectra confirm
the fourfold molecular symmetries as well as diamagnetic
natures of 3a and 3b. The presence of the axial chloride
ligand was also confirmed by replacing it with a phenoxy
ligand (5a and 5b; Scheme 1), the proton signal of which
spectively, which is typical of a MPc with D4h symmetry.[3a,14]
Corresponding to the Q-band absorption, dispersion-type
signals with a peak and trough at l=704 and 720 nm for 3a
and at l=688 and 702 nm for 3b were observed in the mag-
netic circular dichroism (MCD) spectra. Based on the MCD
theory,[15] this signal is recognized as a Faraday A term,
which is indicative of a contribution of transitions to degen-
erate excited states. The minus-to-plus sequence of the A
term in ascending energy indicates greater energy difference
between the HOMO and HOMOꢀ1 (DHOMO) than that
of the LUMO and LUMO+1 (DLUMO).[15]
1
can be observed in the H NMR spectra (see the Supporting
Information). In addition to the X-ray diffraction analysis,
1
these H NMR results support characterization of the cen-
tral gold ion as +3 (d8) oxidation state. Contrary to the
1
clear NMR spectra of 3, the H NMR spectra of 4a and 4b
On the other hand, contrary to the simple MPc-like ab-
sorption of 3, 4 exhibited broad and ill-defined absorptions
with three main bands in the Q-band region (l=684, 634,
in CDCl3 exhibited rather broad peaks probably due to ag-
gregation of 4, which can be inferred from the p–p stacked
Chem. Eur. J. 2012, 00, 0 – 0
ꢀ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
&
3
&
ÞÞ
These are not the final page numbers!

S. Shimizu, N. Kobayashi, D. B. Leznoff et al.
and 593 nm for 4a and 668, 622, and 581 nm for 4b; Fig-
ure 3b).[16] Corresponding to the first and third bands, Gaus-
sian-type signals, which are assigned as Faraday B terms,[15]
were observed at l=684 and 589 nm for 4a and at 668 and
570 nm for 4b in the MCD spectra. Faraday B terms in the
Q-band region are typically observed for Pc analogues with
nondegenerate excited states, which are generally caused by
lower molecular symmetries than C3. Thus, these two bands
can be assigned as split Q bands, whereas the second band
(l=634 for 4a and 622 nm for 4b) is a vibronic band of the
first band. A greater DHOMO than DLUMO is also infer-
red by the minus-to-plus sequence in ascending energy.
Theoretical calculations: To gain further insight into the
electronic structures, DFT and time-dependent (TD)-DFT
calculations at the B3LYP/LanL2DZ level were carried out
on model compounds of 3 and 4,[17] in which substituents at
b-positions were replaced with hydrogen atoms for simplici-
ty. Among the frontier molecular orbitals of 3, the
HOMOꢀ3 and degenerate LUMOs, which relate theoretical
Q-band transitions at l=601 nm with calculated oscillator
strengths of 0.357, are essentially the same as those of con-
ventional MPcs; the degenerate LUMOs are eg-like orbitals,
whereas the HOMOꢀ3 is an a1u-like orbital (Table 1,
Figure 4).[14] The HOMO, HOMOꢀ1, and HOMOꢀ2 local-
Figure 4. Partial frontier molecular orbitals of 3 and 4.
Although the absorption spectra of 4 exhibit similar spec-
tral features to those of phthalocyanine analogues with 18p-
electron conjugation systems, there are still two possibilities
for oxidation states that 4 can take, that is, a 16p-electron
conjugation system as a monovalent (ꢀ1) ligand and an
18p-electron conjugation system as a trivalent (ꢀ3) ligand.
In Michlꢂs perimeter model, which illustrates absorption and
MCD spectroscopic properties of Pcs and porphyrins by
using cyclic polyenes as a simple theoretical model, phthalo-
ꢀ
ize on the Au Cl bonds. Transitions from these MOs to the
degenerate LUMOs are predicted at the longer wavelength
regions, but are forbidden. The TD-DFT calculations on 3
are thus in good agreement with the single Q band with the
degenerate nature as observed for the absorption and MCD
spectra of 3 (Figure 3a).
cyanines are categorized as
(C16H16
a 16 atom 18p-electron
)
system.[18] In this system, the HOMO and
2ꢀ
The theoretical absorption spectrum of 4 also well repro-
duces the observed absorption spectra: two bands at l=588
and 543 nm with large oscillator strengths of 0.343 and
0.306, respectively, are composed of transitions from the
HOMO to the non-degenerate LUMO and LUMO+1 with
a DLUMO value of 0.23 eV (Table 1, Figure 4).
HOMOꢀ1, and the LUMO and LUMO+1 have ML = ꢁ4
and ꢁ5 nodal properties, respectively. In the case of 3, the
HOMOꢀ3, which is essentially the highest occupied orbital
of the phthalocyanine ligand, possesses ML = ꢁ4 nodal
property, whereas the degenerate LUMO and LUMO+1
retain ML = ꢁ5 nodal properties. Because similar nodal pat-
terns can be observed for the HOMO, LUMO, and
LUMO+1 of 4, the conjuga-
tion system of 4 likely falls into
Table 1. Selected transition energies and oscillator strengths of the Q bands and the related wave functions.
the same category of conven-
tional phthalocyanines, that is, a
Compound
l [nm]
f[a]
Wave functions[b]
!
!
2ꢀ
3
2014
1967
1963
1946
1946
1757
1644
1600
1600
688
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.36
0.36
+0.493jL H> +0.493jL+1 Hꢀ1> +…
C16H16 system. In addition to
!
!
+0.494jL H>ꢀ0.494jL+1 Hꢀ1> +…
the phthalocyanine-like absorp-
tion spectrum of 4, these calcu-
lation results reinforce the 18p-
electron conjugation system of
4 and the +3 (d8) oxidation
state of the central gold ion.
!
!
+0.494jL+1 H> +0.494jL Hꢀ1> +…
!
+0.706jL+1 Hꢀ2> +…
!
+0.706jL Hꢀ2> +…
!
+0.707jL+2 Hꢀ2> +…
!
!
+0.495jL+1 H>ꢀ0.495jL Hꢀ1> +…
!
!
+0.530jL+2 H> +0.467jL+2 Hꢀ1> +…
!
!
ꢀ0.530jL+2 Hꢀ1> +0.467jL+2 H> +…
!
+0.705jL+2 Hꢀ3> +…
!
!
!
601
601
+0.677jL+1 Hꢀ3>ꢀ0.137jL Hꢀ6>ꢀ0.122jL Hꢀ3> +…
Interconversion reaction: De-
metalation reactions of 4 with
the goal of obtaining their free-
base forms resulted in the unex-
pected formation of 3. Absorp-
tion spectral changes of 4b in
the presence of trifluoroacetic
!
!
!
+0.677jL Hꢀ3> +0.137jL+1 Hꢀ6> +0.122jL+1 Hꢀ3> +…
!
!
4
663
588
543
0.00
0.34
0.31
+0.695jL+2 H>ꢀ0.112jL+1 H> +…
!
!
+0.687jL H>ꢀ0.155jL+1 Hꢀ1> +…
!
!
!
+0.670jL+1 H> +0.175jL Hꢀ1> +0.109jL+2 H> +…
[a] Oscillator strength. [b] The wave functions based on the eigenvectors predicted by TDDFT. H=HOMO,
L=LUMO.
&
4
&
www.chemeurj.org
ꢀ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 0000, 00, 0 – 0
ÝÝ
These are not the final page numbers!

Gold(II) Phthalocyanine Revisited
FULL PAPER
Scheme 4. Reaction of unsubstituted 1,3-diiminoisoindoline 2c. The prod-
ucts were characterized by the UV/Vis absorption and MALDI-TOF MS
analyses.
Figure 5. Absorption spectral changes of 4b upon heating in the presence
of trifluoroacetic acid.
by reacting the goldACHTUNTRGNE(NUG III) starting material, [KAuCl4], with
acid in toluene at 1008C revealed an increase of an intense
absorption at approximately 696 nm at the expense of the
Q-band of 4b (Figure 5). Surprisingly, the absorption spec-
trum after two hours was identical to that of 3b, and after
chromatographic purification, a goldACTHNUTRGNEUNG(III) phthalocyanine, in
which the axial ligand is likely to be hydroxide or trifluoroa-
cetate, was obtained in 41% yield (Scheme 3). Similar reac-
molten 2c under the same reaction conditions.
The role of solvent in the reaction was then investigated
(Scheme 4). From a reaction of AuCl with 2c in 1-chloro-
naphthalene, blue green and navy blue fractions were col-
lected by silica-gel column chromatography. The blue green
product was identical to 3c by its absorption spectrum
(lmax =683 nm) and MALDI-TOF mass spectrometry (m/z=
709.2, calcd for C32H16N8Au 709.1 [M+ꢀCl]), whereas the
navy blue fraction with the different absorption spectrum
(lmax =665 nm) was identified as the gold complex of unsub-
stituted tribenzo-pentaaza-triphyrinACTHNUTRGNEUNG(4.1.1) (4c) by using
MALDI-TOF mass spectrometry (m/z=723.2, calcd for
C32H16N9Au 723.1 [M+]). In a similar reaction between 2c
and [KAuCl4] in 1-chloronaphthalene, only trace amounts of
3c and 4c were synthesized based on their absorption spec-
tra. Thus, the use of 1-chloronaphthalene as a solvent drasti-
cally altered the product distribution in favor of 4c.
Based on these results, which suggest that goldACTHNUTRGENUG(N III)-con-
Scheme 3. Protonation-promoted ring-expansion reaction of 4.
taining products are formed from both 5,6-disubstituted and
unsubstituted 1,3-diiminoisoindoline, we attempted to syn-
thesize the product isolated in the original report.[4] The re-
ported procedure stated that both gold(I) bromide (AuBr)
and gold powder gave the same product. This is plausible,
because AuBr might not be thermodynamically stable at
room temperature with respect to disproportionation into
tivity of 4a was also observed. Although the mechanism of
this thermal interconversion from 4 to 3 is still uncertain,
the protonation-promoted ring expansion from the triphyrin
system to phthalocyanine is very unusual.
gold metal and gold
(III) bromide.[19] To prevent the forma-
ACHTUNGTRENNUNG
Revisit of the original literature procedure of the AuPc syn-
tion of any gold
ACHTUNGTRENNUNG
thesis: Because the substituted AuPc 3 and Au triphyrin
complexes 4 appear to contain only goldACTHNUTRGNEUNG(III) metal centers,
but not any gold(II) ones, re-examination of the synthesis
and characterization of 1 seemed appropriate. To that end,
AuCl was reacted with molten 1,3-diiminoisoindoline (2c)
was initially used in the attempts to reproduce the reported
procedure.[4] The reaction of gold powder in molten 2c gave
a crude product with a UV/Vis absorption spectrum in the
Q-band region that is similar to the previously reported ab-
sorption spectrum for 1,[4] except for an additional intense
absorption band at l=694 nm (Scheme 5). However, the
spectrum of the crude product very closely matches that of
metal-free phthalocyanine (PcH2) in the Q-band region
(Table S2 in the Supporting Information). A MALDI-TOF
mass spectrum of the crude product showed the presence of
both PcH2 and oligomers of phthalonitrile, which likely re-
sulted from loss of ammonia from 2c followed by oligomeri-
zation, but no gold-containing species were detected. A neg-
ative control experiment was performed by heating 2c to
2408C in the absence of gold powder (see the Supporting
as the first trial, giving
a dark green crude product
(Scheme 4). The MALDI-TOF mass spectrum with peaks
corresponding to AuPc (m/z=709.1, calcd for C32H16N8Au
709.1 [M+ꢀCl]) and AuPcCl (m/z=743.2, calcd for
C32H15N8AuCl 743.1 [M+ꢀH]), and the intense MPc-like Q
band absorption at l=684 nm, which does not match the re-
ported spectrum for 1,[4] characterize the compound as gold
phthalocyanine with a chloride axial ligand (3c), although a
1
satisfactory H NMR spectrum could not be obtained due to
its poor solubility. An identical product was also obtained
Chem. Eur. J. 2012, 00, 0 – 0
ꢀ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
&
5
&
ÞÞ
These are not the final page numbers!

S. Shimizu, N. Kobayashi, D. B. Leznoff et al.
been suggested in recent theoretical studies of AuPc, was
not observed.[22]
Conclusion
In conclusion, by using of 5,6-disubstituted 1,3-diiminoisoin-
dolines with the vastly improved solubility allowed for the
isolation of the first structurally characterized gold phthalo-
cyanines and the gold complexes with a unique triphyrin
structure. Based on spectroscopic analyses as well as theo-
retical calculations, the AuIII metal centers of these com-
plexes were unambiguously revealed. Our attempts to repro-
duce the reported synthesis of 1 resulted in the isolation of
metal-free Pc and oligomers of phthalonitrile when gold
powder was used as a starting material and the unsubstitut-
ed triphyrin 4c was obtained by using AuBr as a starting
material, but no AuII-containing species has been obtained
yet. With this new knowledge of gold phthalocyanines, the
attempted synthesis of the elusive paramagnetic AuIIPc from
the AuIII species can now proceed.
Scheme 5. Revisit of the original synthetic reaction by using Au powder
or AuBr. The products were characterized by the UV/Vis absorption and
MALDI-TOF MS analyses.
Information). A MALDI-TOF mass spectrum of the reac-
tion mixture also showed the presence of PcH2 and oligom-
ers of phthalonitrile. In addition, the UV/Vis absorption
spectrum of the negative control matches that of the reac-
tion between gold powder and 2c.
Because the reactions between gold powder and 2c did
not produce the target AuPc products, AuBr was used in a
final attempt. The UV/Vis absorption spectrum of the ace-
tone extract from the reaction mixture of AuBr and 2c at
2408C matched that of the unsubstituted triphyrin 4c. A
trace amount of blue green product with an absorption
maxima (l=681, 619, 575 nm) closely matching that of
AuPcBr 3d, was extracted from the remaining dark blue
solid by using a mixture of CHCl3 and MeOH.
Experimental Section
General synthetic procedures for 3 and 4: To a 5,6-disubstituted 1,3-di-
iminoisoindoline (0.40 mmol) and AuCl or [KAuCl4] (0.20 mmol) in a
Schlenk tube was added 1-chloronaphthalene (0.3–1.0 mL). The mixture
was deoxygenated via three freeze-pump-thaw degas cycles, and the re-
sulting mixture was stirred for 1.5 h at 2008C under argon. After the re-
action, 1-chloronaphthalene was removed by silica-gel and alumina-gel
column chromatography by using hexane as an eluent. The resultant mix-
ture was purified into fractions containing gold complexes 3 and 4 with
silica-gel column chromatography by using a mixture of CHCl3 and
MeOH (10:1) and CHCl3 as eluent, respectively.
To check for the possible presence of the previously re-
ported AuII phthalocyanine species 1,[4] EPR measurements
were performed on 3b dissolved in chloroform and 3c dis-
solved in 1-chloronaphthalene. Measurements at room tem-
perature, 77 K, and 20 K revealed only trace amounts of par-
amagnetic species, consistent with the conclusion that the
Octa-p-tert-butylphenylphthalocyanine goldACTHNUTRGNE(UNG III) chloride (3a): From the
reaction of 2a (86 mg) and AuCl (25 mg), 3a was obtained in 12%
(11 mg) yield, whereas 3a was obtained in 21% (20 mg) yield by using
2a (88 mg) and [KAuCl4] (41 mg). 1H NMR (CDCl3, 400 MHz, 298 K):
d=9.15 (br s, 8H; a-benzo), 7.42 (d, J=8.0 Hz, 16H; phenyl), 7.36 (d,
J=8.0 Hz, 16H; phenyl), 1.45 ppm (s, 72H; tert-butyl); UV/Vis (CHCl3):
lmax (e)=259 (73200), 308 (79700), 643 (32800), 714 nm (143000); ESI-
FT-ICR-MS: m/z: calcd for C112H112N8Au: 1765.8670 [M+ꢀCl]; found:
1765.8641.
complex does not contain AuII, and that there were no
9
ligand radicals present. The putative AuII (5d , S=1= ) com-
2
plex would be expected to show a distinctive EPR spectrum
with g values exhibiting uniaxial symmetry, due to the antici-
pated approximately tetragonal coordination environment
of the gold ion. Furthermore, distinctive line splitting from
hyperfine interactions with the gold nucleus (197Au, 100%,
I=3/2) and superhyperfine interactions with nitrogen (14N,
99.632%, I=1) atoms from the Pc ligand are also potential-
ly observable. The published EPR measurement of 1 reports
only the perpendicular part of the spectrum and correspond-
GoldACTHNUTRGNENG(U III) octa-p-tert-butylphenyl-[18]tribenzo-pentaaza-triphyrinACHTUNGTRENNUNG(4.1.1)
(4a): From the reaction of 2a (86 mg) and AuCl (25 mg), 4a was ob-
tained in 15% (14 mg) yield, whereas only a trace amount of 4a was ob-
tained by using 2a (88 mg) and [KAuCl4] (41 mg). 1H NMR
([D6]benzene, 500 MHz, 298 K): d=9.81 (br s, 1H; a-benzo), 9.62 (br s,
1H; a-benzo), 9.54 (br s, 1H; a-benzo), 9.42 (br s, 1H; a-benzo), 9.00 (br
s, 1 H; a-benzo), 7.95 (br, 3H; a-benzo), 7.77 (d, J=6.9 Hz, 2H; phenyl),
7.70 (d, J=6.5 Hz, 2H; phenyl), 7.6–7.2 (m, 28H; phenyl), 1.39 (s, 9H;
tert-butyl), 1.34 (s, 9H; tert-butyl), 1.32 (br, 36H; tert-butyl), 1.27 (s, 9H;
tert-butyl), 1.18 ppm (s, 9H; tert-butyl); UV/Vis (toluene): lmax (e)=378
(57500), 593 (33400), 634 (32700), 684 nm (89200); ESI-FT-ICR-MS: m/
z: calcd for C112H112N9AuNa: 1802.8598 [M+ +Na]; found: 1802.8609.
ing values of g?, A?ACHUTGTNRENNUG( ACHTNUGTRENNUNG
197Au), and A?(14N).[4] The reported
spectroscopic parameters look similar to those reported for
other MPcs, such as CuPc[20] and AgPc,[21] which can be pos-
sible trace contaminants in the reaction, and the quality of
the EPR data shown is not sufficient for further discussion
on the observed species with confidence. Furthermore, any
spectra consistent with the earlier report or other interpreta-
tions of an AuII center or a ligand-based radical, which has
Octa-p-tert-butylphenyloxyphthalocyanine goldACTHNUGRTNEUNG(III) chloride (3b): From
the reaction of 2b (180 mg) and AuCl (49 mg), 3b was obtained in 14%
(27 mg) yield, whereas 3b was obtained in 14% (27 mg) yield by using
2b (181 mg) and [KAuCl4] (77 mg). 1H NMR (CDCl3, 400 MHz, 298 K):
d=8.67 (br s, 8H; a-benzo), 7.40 (d, J=8.0 Hz, 16H; phenyl), 7.18 (d,
J=8.0 Hz, 16H; phenyl), 1.34 ppm (s, 72H; tert-butyl); UV/Vis (CHCl3):
&
6
&
www.chemeurj.org
ꢀ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 0000, 00, 0 – 0
ÝÝ
These are not the final page numbers!

Gold(II) Phthalocyanine Revisited
FULL PAPER
lmax (e)=625 (27000), 696 nm (150000); ESI-FT-ICR-MS: m/z: calcd for
C112H112N8O8Au: 1893.8263 [M+ꢀCl]; found: 1893.8237.
both green and blue compounds were also obtained (Scheme S1 in
the Supporting Information).
[10] Crystallographic data for 3a: C117H123N8O1Au1Cl7; Mw =
Gold
(III)
octa-p-tert-butylphenyloxy-[18]tribenzo-pentaaza-triphyrin-
2102.35 gmolꢀ1; triclinic; space group P1 (no. 2); a=18.687(4), b=
¯
ACHTUNGTRENNUNG(4.1.1) (4b): From the reaction of 2b (183 mg) and AuCl (51 mg), 4b was
20.118(4), c=20.811(5) ꢁ; a=67.869(3), b=89.655(3), g=
80.793(3)8; V=7142(3) ꢁ3; Z=2; 1calcd =0.978 gcmꢀ3; T=ꢀ1738C;
33464 measured reflections; 24548 unique reflections (Rint =0.0279);
R=0.0522; Rw =0.1570 (all data); GOF=1.058. CCDC-833360 con-
tains the supplementary crystallographic data for this paper. These
data can be obtained free of charge from The Cambridge Crystallo-
graphic Data Centre via www.ccdc.cam.ac.uk/data_request/cif.
[11] R. Timkovich, A. Tulinsky, Inorg. Chem. 1977, 16, 962–963.
obtained in 22% (43 mg) yield, whereas 4b was obtained in 18%
(35 mg) yield by using 2b (178 mg) and [KAuCl4] (79 mg). Assignment of
the 1H NMR spectrum of 4b was prevented by severe overlaps of peaks
due to aggregation and low molecular symmetry of 4b. ESI-FT-ICR-MS:
m/z: calcd for C112H112N9O8AuNa: 1930.8192 [M+ +Na]; found:
1930.8216; UV/Vis (toluene): lmax (e)=372 (52000), 581 (30600), 622
(30600), 668 nm (81200).
[12] Crystallographic
data
for
4a:
C236H234N18Au2Br2;
Mw =
3876.17 gmolꢀ1; triclinic; space group P1 (no. 2); a=24.795(7), b=
25.521(7), c=25.556(8) ꢁ; a=66.651(3), b=82.965(4), g=
64.660(3)8; V=13397(7) ꢁ3; Z=2; 1calcd =1.436 gcmꢀ3; T=ꢀ1738C;
¯
Acknowledgements
126815 measured reflections; 47029 unique reflections (Rint
=
D.B.L. and C.J.W. are grateful to NSERC of Canada for support of this
research. E.W.Y.W. was supported by an NSERC CGS-D Scholarship,
and a JSPS Summer Fellowship. This work was partly supported by a
Grant-in-Aid for Scientific Research (B: No. 23350095 and C: No.
23550040) from JSPS and a Grant-in-Aid for Scientific Research on In-
novative Areas (No. 20108007, “pi-Space”) from MEXT. The authors
thank Prof. T. Iwamoto and Dr. S. Ishida, Tohoku University for X-ray
measurements.
0.0612); R=0.0604; Rw =0.1719 (all data); GOF=1.061. CCDC-
833361 contains the supplementary crystallographic data for this
paper. These data can be obtained free of charge from The Cam-
bridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_
request/cif.
[13] B. Franck, A. Nonn, Angew. Chem. 1995, 107, 1941–1957; Angew.
Chem. Int. Ed. Engl. 1995, 34, 1795–1811.
[14] T. Fukuda, N. Kobayashi in Handbook of Porphyrin Science, Vol. 9
(Eds.: K. M. Kadish, K. M. Smith, R. Guilard), World Scientific, Sin-
gapore, 2010, and references therein.
[1] a) Phthalocyanines: Properties and Applications, Vol. 1–4 (Eds.:
C. C. Leznoff, A. B. P. Lever), Wiley, New York, 1989; b) The Por-
phyrin Handbook, Vol. 19 (Eds.: K. M. Kadish, K. M. Smith, R. Gui-
lard), Academic Press, San Diego, 2003.
[2] N. B. McKeown, Phthalocyanine Materials: Synthesis, Structure, and
Function, Cambridge University Press, Cambridge, 1998.
[3] a) M. J. Stillman, T. Nyokong in Phthalocyanines: Properties and
Applications, Vol. 1 (Eds.: C. C. Leznoff, A. B. P. Lever), Wiley, New
York, 1989, pp. 133–289; b) M. Hanack, H. Heckmann, R. Polley in
Methods of Organic Chemistry (Houben–Wenyl), Vol. E9d (Ed.: E.
Schaumann), Thieme, New York, 1998, p.717.
[4] A. MacCragh, W. S. Koski, J. Am. Chem. Soc. 1965, 87, 2496–2497.
[5] A. Laguna, M. Laguna, Coord. Chem. Rev. 1999, 193–195, 837–856.
[6] a) J. D. Basil, H. H. Murray, J. P. Fackler Jr., J. Tocher, A. M.
Mazany, B. Trzcinska-Bancroft, H. Knachel, D. Dudis, T. J. Delord,
D. Marler, J. Am. Chem. Soc. 1985, 107, 6908–6915; b) M. Bardaji,
M. Concepciꢃn Gimeno, P. G. Jones, A. Laguna, M. Laguna, Orga-
nometallics 1994, 13, 3415–3419.
[7] a) A. J. Blake, J. A. Greig, A. J. Holder, T. I. Hyde, A. Taylor, M.
Schrçder, Angew. Chem. 1990, 102, 203–204; Angew. Chem. Int. Ed.
Engl. 1990, 29, 197–198; b) J. L. Shaw, J. Wolowska, D. Collison,
J. A. K. Howard, E. J. L. McInnes, J. McMaster, A. J. Blake, C.
Wilson, M. Schrçder, J. Am. Chem. Soc. 2006, 128, 13827–13839;
c) D. Huang, X. Zhang, E. J. L. McInnes, J. McMaster, A. J. Blake,
E. S. Davies, J. Wolowska, C. Wilson, M. Schrçder, Inorg. Chem.
2008, 47, 9919–9929; d) L. Ihlo, R. Bçttcher, R.-M. Olk, R. Kirmse,
Inorg. Chim. Acta 1998, 281, 160–164; e) R. L. Schlupp, A. H. Maki,
Inorg. Chem. 1974, 13, 44–51; f) J. H. Waters, H. B. Gray, J. Am.
Chem. Soc. 1965, 87, 3534–3535.
[15] J. Mack, M. J. Stillman, N. Kobayashi, Coord. Chem. Rev. 2007, 251,
429–453.
[16] Aggregation of 4 was not observed in the absorption spectra at con-
centrations ranging from 1 to 20 mm (Figures S1 and S2 in the Sup-
porting Information).
[17] Gaussian 09, M. J. Frisch, G. W. Trucks, H. B. Schlegel, G. E. Scuse-
ria, M. A. Robb, J. R. Cheeseman, G. Scalmani, V. Barone, B. Men-
nucci, G. A. Petersson, H. Nakatsuji, M. Caricato, X. Li, H. P.
Hratchian, A. F. Izmaylov, J. Bloino, G. Zheng, J. L. Sonnenberg, M.
Hada, M. Ehara, K. Toyota, R. Fukuda, J. Hasegawa, M. Ishida, T.
Nakajima, Y. Honda, O. Kitao, H. Nakai, T. Vreven, J. A. Montgom-
ery, Jr., J. E. Peralta, F. Ogliaro, M. Bearpark, J. J. Heyd, E. Broth-
ers, K. N. Kudin, V. N. Staroverov, R. Kobayashi, J. Normand, K.
Raghavachari, A. Rendell, J. C. Burant, S. S. Iyengar, J. Tomasi, M.
Cossi, N. Rega, J. M. Millam, M. Klene, J. E. Knox, J. B. Cross, V.
Bakken, C. Adamo, J. Jaramillo, R. Gomperts, R. E. Stratmann, O.
Yazyev, A. J. Austin, R. Cammi, C. Pomelli, J. W. Ochterski, R. L.
Martin, K. Morokuma, V. G. Zakrzewski, G. A. Voth, P. Salvador,
J. J. Dannenberg, S. Dapprich, A. D. Daniels, ꢄ. Farkas, J. B. Fores-
man, J. V. Ortiz, J. Cioslowski, D. J. Fox, Gaussian, Inc., Wallingford
CT, 2009.
[18] J. Michl, J. Am. Chem. Soc. 1978, 100, 6801–6811.
[19] E. M. W. Janssen, G. A. Wiegers, J. Less-Common Met. 1978, 57,
P59–P67.
[20] a) C. Finazzo, C. Calle, S. Stoll, S. Van Doorslaer, A. Schweiger,
Phys. Chem. Chem. Phys. 2006, 8, 1942–1953; b) C. M. Guzy, J. B.
Raynor, M. C. R. Symons, J. Chem. Soc. A 1969, 2299–2303; c) R.
Heucher, G. V. R. Chanramouli, P. T. Manoharan, J. Porphyrins
Phthalocyanines 1998, 2, 423–427; d) E. M. Roberts, W. S. Koski, J.
Am. Chem. Soc. 1961, 83, 1865–1867.
[8] a) K. M. Kadish, W. E, Z. Ou, J. Shao, P. J. Sintic, K. Ohkubo, S. Fu-
kuzumi, M. J. Crossley, Chem. Commun. 2002, 356–357; b) Z. Ou,
K. M. Kadish, W. E, J. Shao, P. J. Sintic, K. Ohkubo, S. Fukuzumi,
M. J. Crossley, Inorg. Chem. 2004, 43, 2078–2086.
[21] A. MacCragh, W. S. Koski, J. Am. Chem. Soc. 1963, 85, 2375–2376.
[22] D. Carrascal, L. Fernꢅndez-Seivane, J. Ferrer, Phys. Rev. B 2009, 80,
184415–184420.
[9] From a similar reaction by using 5-tert-butyl-1,3-diiminoisoindoline,
which is one of the most conventional precursors in MPc syntheses,
Received: May 15, 2012
Published online: && &&, 0000
Chem. Eur. J. 2012, 00, 0 – 0
ꢀ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
&
7
&
ÞÞ
These are not the final page numbers!

S. Shimizu, N. Kobayashi, D. B. Leznoff et al.
Reinvestigation of a putative gold(II)
phthalocyanine, which was synthesized
in 1965 and has not been fully charac-
EPR Spectroscopy
E. W. Y. Wong, A. Miura,
M. D. Wright, Q. He, C. J. Walsby,
S. Shimizu,* N. Kobayashi,*
terized, provided only gold
plexes, gold(III) phthalocyanine chlor-
ide and a gold(III) complex of an
ACHTUNGTRENN(UNG III) com-
AHCTUNGTRENNUNG
AHCTUNGTRENNUNG
D. B. Leznoff* ................ &&&& — &&&&
unprecedented ring-contracted phtha-
locyanine (see figure). Interconversion
reaction of the ring-contracted species
to goldACTHNUGTRNEUNG(III) phthalocyanine was also
revealed.
Gold(II) Phthalocyanine Revisited:
Synthesis and Spectroscopic Properties
of GoldACHTUNGTRENNUNG(III) Phthalocyanine and an
Unprecedented Ring-Contracted
Phthalocyanine Analogue
Gold phthalocyanine (Pc) has long been cited……as
a rare example of a paramagnetic gold(II)
compound. In the process of targeting soluble
gold(II) Pc analogues, an unprecedented ring-
contracted Pc analogue was discovered, and a gold-
AHCTUNGTREG(NNNU III) Pc was isolated, representing the first structur-
ally characterized Pc-containing gold. However, no
gold(II)-containing species could be identified with
either substituted or simple Pc ligands. For more
information, see the Full Paper by S. Shimizu, N.
Kobayashi, D. Leznoff, and co-workers on page &
& ff.
&
8
&
www.chemeurj.org
ꢀ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 0000, 00, 0 – 0
ÝÝ
These are not the final page numbers!