Anthraphen: A Salphen-Like Non-Innocent Tetradentate Anthraquinone Imine Dye - Coordination and Electrochemistry

Article abstract of DOI:10.1002/ejic.201501355

A new, highly redox-active chromophore ligand, H₂(anthraphen) (1), containing two o-phenylenediamine-linked anthraquinone imine units has been synthesized in a three-step synthesis and fully characterized by X-ray crystallography, UV/Vis spectroscopy, and cyclic voltammetry. The dark-red dye 1 shows molar extinction coefficients of up to 47000 L mol^-1 cm^-1 and four reversible reduction processes. This dianionic N₂O₂ ligand, with a significantly extended π system, offers a salphen-like binding cavity for metal coordination, as has been demonstrated by the synthesis of [K₂(anthraphen)] (2) and the transition-metal complexes of Ti^IV (3), V^IV (4), Fe^II (5), Fe^III (6), Co^II (7), Ni^II (8), Cu^II (9), Pd^II (10), Pt^II (11), and Zn^II (12). These metal chromophores have colors ranging from dark-red, violet, green to black. Their optical and electrochemical properties were investigated and compared with those of the diprotic ligand. Coordination led to an increase in the molar extinction coefficients up to 66400 L mol^-1 cm^-1 in the case of [V(anthraphen)O] (4), broadening of the absorption bands in the visible-light region as well as a redshift of the lowest-energy absorption band. The lowest-energy absorption observed for these complexes to date is for [Ni(anthraphen)] (8) at 784 nm. The metal chromophores exhibit up to five fully reversible oxidation and reduction processes.

Full text of DOI:10.1002/ejic.201501355

DOI: 10.1002/ejic.201501355
Full Paper
Redox-Active Ligands
Anthraphen: A Salphen-Like Non-Innocent Tetradentate
Anthraquinone Imine Dye – Coordination and Electrochemistry
[
a]
[a]
[a]
[a]
Christian Prinzisky, Andreas Jacob, Marcus Harrer, Michael Elfferding, and
Jörg Sundermeyer*[
a]
Abstract: A new, highly redox-active chromophore ligand, These metal chromophores have colors ranging from dark-red,
H2(anthraphen) (1), containing two o-phenylenediamine-linked violet, green to black. Their optical and electrochemical proper-
anthraquinone imine units has been synthesized in a three-step ties were investigated and compared with those of the diprotic
synthesis and fully characterized by X-ray crystallography, ligand. Coordination led to an increase in the molar extinction
UV/Vis spectroscopy, and cyclic voltammetry. The dark-red coefficients up to 66400 L mol– cm in the case of [V(anthra-
1
–1
dye
7000 L mol cm–1 and four reversible reduction processes. light region as well as a redshift of the lowest-energy absorp-
This dianionic N O ligand, with a significantly extended π sys- tion band. The lowest-energy absorption observed for these
1 shows molar extinction coefficients of up to phen)O] (4), broadening of the absorption bands in the visible-
–
1
4
2
2
tem, offers a salphen-like binding cavity for metal coordination, complexes to date is for [Ni(anthraphen)] (8) at 784 nm. The
as has been demonstrated by the synthesis of [K (anthraphen)] metal chromophores exhibit up to five fully reversible oxidation
2
IV
IV
II
(
2) and the transition-metal complexes of Ti (3), V (4), Fe (5), and reduction processes.
Fe (6), Co (7), Ni (8), Cu (9), Pd (10), Pt (11), and Zn (12).
III
II
II
II
II
II
II
Introduction
ing co-polymerization of carbon dioxide and oxiranes to poly-
carbonates with chromium and cobalt salen complexes.
[
13,14]
Schiff-base ligands, easily obtained by straightforward conden-
sation reaction of an aldehyde or ketone with a primary amine,
have become a basic module of coordination chemistry since
Recently, salen derivatives have attracted great interest be-
[
15–21]
cause of their redox non-innocent behavior.
The interplay
[
1]
of redox-active transition-metal ions and pro-radical ligands is
an area of considerable research effort because redox processes
in some enzymes involve not only metal centers but also coor-
their first description by Hugo Schiff in 1864. Metal complexes
of these σ-donor and π-acceptor ligands have plenty of applica-
[
2–4]
tions
and have been known since the mid-nineteenth cen-
[
22,23]
[
5]
dinated non-innocent ligands
applications in catalysis.
and also because of their
tury, even before the general preparation of Schiff-base li-
[
24]
[
1,6]
Depending on the relative energies
gands themselves.
of the redox-active orbitals, metal complexes with such non-
innocent ligands exist in two limiting descriptions, either as a
Probably the most prominent Schiff-base ligand is H (salen),
2
obtained by the spontaneous condensation reaction of 2 equiv-
alents of salicylaldehyde with 1 equivalent of ethylenediamine.
This tetradentate dianionic ligand was synthesized for the first
time by Pfeiffer et al. in 1933. Metal complexes of salen li-
gands are an important class of compounds and stabilize met- quinones (H
als in low as well as higher oxidation states
donor properties of the phenolate and π-acceptor properties of benzosemiquinone anion (sbq ) to the neutral benzoquinone
the imine group. Salen complexes have found numerous appli- ligand (bq). o-Phenylenediamine (H pda) and its derivatives are
cations in heterogeneous and homogeneous catalysis, includ- classical examples of non-innocent N-donor ligands.
n+
·
metal–ligand radical [M (L )] or as a higher-valent metal–
(
n+1)+
–
[19]
anionic ligand complex [M
(L )].
[
7]
Typical examples of non-innocent ligands are o-benzohydro-
[
25–31]
bq),
2
which can be oxidized from the doubly
[
8–14]
2–
due to the π- deprotonated dianionic catecholate (cat ) via the radical o-
1
–
2
[
22,32–34]
ing in the asymmetric epoxidation of olefins by chiral manga- They can form complexes in the doubly deprotonated dianionic
[
9,10]
2–
nese and chromium salen complexes,
the asymmetric catal- form (pda ), which in turn can be oxidized to the o-benzosemi-
[
11,12]
1–
ysis of epoxide ring-opening reactions,
and the ring-open- quinone diiminato radical imino anion (sbqdi ) and to the
neutral o-benzoquinone diimine ligand (bqdi). Furthermore, o-
[
a] Department of Chemistry and Material Sciences Center,
Philipps-Universität Marburg,
benzoquinone imine (H
phenylenediamine, is an interesting non-innocent ligand
and has been studied by Pierpont
their co-workers. Structurally related to o-quinones and o-quin-
one imines are p-quinones and p-quinone imines, respectively
(Scheme 1, a).
2
bqi), as a hybrid of o-quinone and o-
[
35–37]
Hans-Meerwein-Straße 4, 35032 Marburg, Germany
E-mail: jsu@chemie.uni-marburg.de
https://www.uni-marburg.de/fb15/ag-sundermeyer
Supporting information for this article is available on the WWW under
http://dx.doi.org/10.1002/ejic.201501355.
[38]
[39]
and Wieghardt
and
Eur. J. Inorg. Chem. 2016, 477–489
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Scheme 1. Different oxidation states of (a) p-benzoquinone imine and (b) juglone imine.
Quinone, phenylene diamine, and quinone imine ligands in quinone with phenylene-1,2-diamine, which is by no means a
their ligand-oxidized form are weak σ donors and strong π ac- straightforward selective reaction. The targets were non-inno-
2
–
ceptors. To achieve polydentate p-naphthoquinone or p- cent [N O ] hybrid ligands incorporating salphen and anthra-
2
2
naphthoquinone imine ligands with σ-donor properties like quinone building blocks (Figure 1), specifically the tetradentate
salen derivatives, a hydroxy group has to be introduced into phenylene-bridged anthraquinone imine N,N′-bis(1-hydroxy-10-
the peri position, which leads to juglone and juglone imine de- oxo-9-anthryl)-o-phenylendiimine, named H (anthraphen) (1) in
2
rivatives (Scheme 1, b). No transition-metal complexes of the following. Similar to most popular organic chromophore
juglone imine derivatives have been reported in the literature. complexes such as metal phthalocyanines or porphyrins, the
For this work we chose the hydroxyanthraquinone motif (Fig- targeted anthraphen metal dyes may have broad application as
ure 1) to avoid side-reactions at the 2- and 3-positions redox catalysts, as photophysically active materials in light-
(
Scheme 1, b). Furthermore, anthraquinones are the largest driven processes, or as organic semiconductor materials. Here
group of naturally occurring quinones. Alizarin, a component of we report the synthesis of the parent ligand 1, its deprotona-
the madder root pigment, has been used as dyestuff since the tion to potassium salt 2, its coordination chemistry, its structural
times of Ancient Egypt and became economically important as and chromophore properties, and its electrochemistry within a
the mordant dye Turkey Red in Western Europe in the late me- series of unique transition-metal anthraphen chelate complexes
dieval centuries. Ancient as well as modern 1-hydroxy-9,10- 3–12.
anthraquinone derivatives are prominent due to their brilliance,
color fastness, and photostability as well as for their ability to
form, for example, Al and Ca complexes on fibers. This historical
background and the fact that no anthraquinone imine com-
plexes have been reported in the literature prompted us to
Results and Discussion
study the condensation reaction of 1-hydroxy-9,10-anthra-
Synthesis
The direct condensation of 1-hydroxy-9,10-anthraquinone with
o-phenylenediamine is hampered by the unselective redox re-
actions of this nucleophile–electrophile pair. The conjugation
of the carbonyl groups with the aromatic system and the steric
hindrance created by the hydrogen atoms in the peri positions
causes ordinary 9,10-anthraquinones to react only with strong
[
40]
and hard nucleophiles under harsh conditions. Our synthesis
of the tetradentate H (anthraphen) (1) follows a three-step pro-
2
cedure (Scheme 2) involving the literature-known regioselective
activation of the keto function in the peri position by the medi-
[
41,42]
ating hydroxy group.
1-Hydroxyanthraquinone (16) was
treated with acetic anhydride to form 1-acetoxy-9,10-anthra-
quinone (17), thereby introducing an acetoxy group as auxiliary
(
Yp = 98 %) that facilitates and controls the selective nucleo-
philic substitution at the 9-position (for numbering see Fig-
ure 2). The second step leads, by migration of the acetoxy
group in alkaline media using sodium methoxide in tetrahydro-
2
Figure 1. Structural combination of H (salphen) (14) and alizarin (15) to ob-
[
40,43,44]
tain the new tetradentate ligand H
2
(anthraphen) (1).
furan/methanol, to the dimethoxy acetal 18.
After work-
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up with acetic acid, the pure 1-hydroxy-9,9-dimethoxy-10-an-
throne (18) can be isolated by column chromatography on de-
Table 1. Synthesized metal complexes, reagents used, reaction conditions,
and product yields for 2–12.
activated silica gel (Y = 69 %). These two steps are necessary to
Compound[a]
(ap)] (2)
Ti(ap)(NMe
[V(ap)O] (4)
Fe(ap)] (5)
Fe(ap)Cl] (6)
p
Reagents
KH
Solvents and conditions
Y
p
[%]
activate the system for the subsequent condensation reaction.
Furthermore, these two steps are essential to selectively substi-
[
[
K
2
thf, r.t., 1 h
58
2 2
)
] (3) Ti(NMe
[VO(acac)
[Fe(hmds)
1. [K(hmds)]
. FeCl
[Co(hmds)
Ni(OAc) ·4H O
2
)
2
toluene, reflux, 0.5 h
toluene, reflux, 18 h
thf, reflux, 0.5 h
toluene, reflux, 0.5 h
thf, reflux, 1 h
toluene, reflux, 2.5 h
methanol, reflux, 3.5 h
methanol, reflux, 3 h
dmf, r.t., 15 min
86
86
93
72
[
45]
tute the 9-carbonyl. An alternative route
using phosphorus
2
]
2
(thf)]
[
[
pentachloride was also tested but led to lower yields. H (anthra-
2
phen) (1) was obtained by the reaction of 1-hydroxy-9,9-di-
methoxy-10-anthrone (18) with 0.5 equivalents of o-phenylene-
diamine (19) in toluene at reflux and was purified by column
2
3
[Co(ap)] (7)
2
(thf)]
91
88
93
20
[Ni(ap)] (8)
[Pd(ap)] (9)
2
2
chromatography (Y = 72 %).
Pd(OAc)
1. NaOAc
. Zeise's dimer[b]
Cu(OAc) ·H
[Zn(hmds)
2
p
[Pt(ap)] (10)
2
110 °C, 4 d
methanol, reflux, 3.5 h
toluene, reflux, 1.5 h
[Cu(ap)] (11)
2
2
O
85
62
[Zn(ap)] (12)
2
]
[
2 4 2
a] ap: anthraphen. [b] Zeise's dimer: [{PtCl(C H )}(μ-Cl)] .
NMR Spectroscopy
The diamagnetic compounds 1-acetoxy-9,10-anthraquinone
(17), 1-hydroxy-9,9-dimethoxy-10-anthrone (18), H2(anthra-
phen) (1), [Ti(anthraphen)(NMe ) ] (3), [Ni(anthraphen)] (8),
2
2
[Pd(anthraphen)] (9), [Pt(anthraphen)] (10), and [Zn(anthra-
phen)] (12) were analyzed by NMR spectroscopy (but not
[
K (anthraphen)] (2) due to its poor solubility in common sol-
2
1
vents). These compounds were fully characterized by H and
1
3
C NMR spectroscopy, and all signals were chemically un-
equal and so a full assignment was carried out by means of 2D
COSY, HMQC, and HMBC experiments, except for [Ti(anthra-
phen)(NMe ) ] (3) and [Pt(anthraphen)] (10), for which no rea-
2
2
1
sonable data were obtained due to their low solubility. All H,
C, and 2D NMR spectra are presented in the Supporting Infor-
1
3
mation.
Mass Spectrometry
The precursors 17 and 18, the ligand 1, and the metal com-
plexes 3–12, but not the potassium salt 2, were analyzed by
mass spectrometry. Compounds 17 and 18 were ionized by
electrospray ionization, whereas ligand 1 and the complexes 3–
12 were ionized by atmospheric-pressure chemical ionization
(APCI). All the data and high-resolution mass spectra can be
found in the Supporting Information.
Single-Crystal XRD Structures
2
Scheme 2. Synthesis of H (anthraphen) (1) and its complexes 2–12.
Single crystals of H (anthraphen) (1), [V(anthraphen)O] (4),
2
[Fe(anthraphen)Cl] (6), [Co(anthraphen)] (7), [Ni(anthraphen)]
Subsequently, H (anthraphen) (1) was treated with a series (8), [Pd(anthraphen)] (9), [Pt(anthraphen)] (10), [Cu(anthra-
2
of metal cations. Depending on the cation, the corresponding phen)py] (11), and [Zn(anthraphen)] (12) were obtained and
acetates, acetylacetonates, or amides were used for the metal- analyzed by XRD. Single crystals of 1 were grown by slow evap-
ation processes (Table 1). In the case of iron(III), the correspond- oration from a saturated toluene solution, 4 and 7 by diffusion
ing metal halide was used, which reacted with the ligand after of pentane into a saturated dichloromethane solution, 6 by
its deprotonation with potassium bis(trimethylsilyl)amide.
cooling a saturated tetrahydrofuran solution from room tem-
For most substances, single crystals suitable for XRD were perature to –20 °C, 8, 10, and 12 by slow evaporation from
obtained. Unless stated otherwise, all compounds were ana- saturated tetrahydrofuran solutions, 9 by the diffusion of pent-
lyzed by NMR, IR, and UV/Vis spectroscopy, mass spectrometry, ane into a saturated tetrahydrofuran solution, and 11 by slow
cyclic voltammetry, and elemental analysis.
evaporation from a saturated pyridine solution.
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The numbering of the anthraquinone imine structure is in [Fe(anthraphen)Cl] (6, P2 /n) crystallizes with one complex mol-
1
accord with IUPAC, and is shown in Figure 2. Additional crystal- ecule in the asymmetric unit, [Co(anthraphen)] (7, P2 /c) crystal-
1
lographic data and experimental parameters are listed in the lizes with one complex and one dichloromethane molecule in
Supporting Information.
the asymmetric unit, and [Ni(anthraphen)] (8, P2 /c) crystallizes
1
with one complex and one tetrahydrofuran molecule in the
asymmetric unit. [Pd(anthraphen)] (9, P2 /n) crystallizes with
1
one complex and half a tetrahydrofuran molecule in the asym-
metric unit. The half tetrahydrofuran molecule is disordered
through an inversion center. It should be noted that the reflec-
tion data show a low ratio of observed/unique reflections of
4
6 %. [Pt(anthraphen)] (10, P2 /c) crystallizes isostructurally to
1
[Co(anthraphen)] (7), with one complex and one dichlorometh-
ane molecule in the asymmetric unit, [Cu(anthraphen)py] (11,
P2 /c) crystallizes with one complex pyridine adduct, one water,
1
2
Figure 2. Numbering of the H (anthraphen) ligand 1 (left) and the metal–
anthraphen complexes 2–12 (right).
and one disordered pyridine molecule in the asymmetric unit,
The tetradentate H (anthraphen) ligand (1) crystallizes in the and [Zn(anthraphen)] (12) crystallizes in the triclinic space
2
monoclinic space group C2/c and the asymmetric unit consists group P1. The molecular structures of 4 and 6–12 are shown in
¯
of half a molecule with crystallographically induced mirror sym- Figure 4.
metry. The parameters of the intramolecular hydrogen bond
between O–H as donor and N as acceptor [d(O1···N1) =
2
.537(3) Å; <(O1H1N1) = 156(3)°; Figure 3a] are in the same
range as those of H (salen) [d(O1···N1) 2.596(2) Å;
and H (salphen) [d(O1···N1) = 2.564 Å;
=
2
[
46]
<
<
(O1H1N1) = 146.0°]
2
[
47]
(O1H1N1) = 150.0°].
Figure 4. Molecular structures of (a) [V(anthraphen)O] (4), (b) [Fe(anthra-
phen)Cl] (6), (c) [Co(anthraphen)] (7), (d) [Ni(anthraphen)] (8), (e) [Pd(anthra-
phen)] (9), (f) [Pt(anthraphen)] (10), (g) [Cu(anthraphen)py] (11), and
(
h) [Zn(anthraphen)] (12). For clarity, solvent molecules and hydrogen atoms
are not shown. Note that the pyridine molecule of [Cu(anthraphen)py] (11)
had to be constrained and restrained with the commands EADP and ISOR.
Figure 3. (a) Molecular structure, (b) illustration of intra- and intermolecular
π stacking, and (c) column-like structure of H (anthraphen) (1).
The complexes show weak intermolecular hydrogen bonds
between C–H as donor and O as acceptor (see the Supporting
2
Furthermore, it is notable that the two anthraquinone imine Information). Furthermore, intermolecular π stacking can be ob-
moieties show intermolecular (shortest distance found: 3.33 Å) served for [Co(anthraphen)] (7), [Ni(anthraphen)] (8), and [Pt-
as well as intramolecular (shortest distance found: 3.43 Å) π (anthraphen)] (10; Figure 5, a–c). [Co(anthraphen)] (7) and
stacking (Figure 3, b). As a result of the π stacking, H (anthra- [Pt(anthraphen)] (10) also show column-like structures with al-
2
phen) (1) forms a column-like structure (Figure 3, c). The angle ternating Co–Co distances of 6.8754 and 3.3612 Å and Pt–Pt
α of 56.1° between the phenylene bridge and the carbon atoms distances of 6.7429 and 3.3076 Å, respectively (Figure 5, a,b).
of the quinone imine moieties (Figure 3, b) indicates weak π The shorter Co–Co and Pt–Pt distances indicate intermolecular
conjugation in the aromatic systems.
π stacking between the quinone imine moieties (Figure 5, b).
[
V(anthraphen)O] (4) crystallizes in the monoclinic space [V(anthraphen)O] (4), [Fe(anthraphen)Cl] (6), [Cu(anthra-
group P2 /c, with two complex molecules and several disor- phen)py] (11), and [Zn(anthraphen)] (12) show column-like
1
dered dichloromethane molecules in the asymmetric unit, structures (Figure 5, d–g), but with no clearly identifiable π
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stacking due to the strong bending of the anthraquinone imine
structure and in the case of [V(anthraphen)O] (4) due to interac-
tions with numerous solvent molecules. For [Pd(anthraphen)]
Table 2. Bond lengths of the anthraphen and literature-known salen com-
plexes.
Compound[a]
d(N1–M) [Å] d(N2–M) [Å] d(O1–M) [Å]
d(O3–M) [Å]
(
9), neither π stacking nor a column-like structure was ob-
[
V(ap)O] (4)
V(salen)O][48]
Fe(ap)Cl] (6)
2.080(4)
.083(4)
2.046(1)
.055(1)
2.131(4)
2.098(9)
1.874(2)
1.88(1)
1.864(3)
1.8519(10)
1.974(5)
1.952(2)
1.967(4)
1.938(5)
1.898(5)
1.958(2)
1.952(3)
2.072(5)
2.081(4)
2.081(4)
2.054(1)
2.057(1)
2.131(5)
2.091(10)
1.8806(19)
1.88(1)
1.873(3)
1.8494(10)
1.962(5)
1.957(2)
1.972(3)
1.950(5)
1.900(5)
1.959(2)
1.947(3)
2.078(6)
1.921(3)
1.897(4)
1.921(1)
1.924(1)
1.882(4)
1.898(7)
1.8303(16)
1.88(1)
1.832(2)
1.8494(10)
1.976(4)
1.9981(16)
1.982(3)
2.006(4)
1.980(5)
1.945(2)
1.885(3)
2.053(5)
1.902(3)
1.918(3)
1.922(1)
1.925(1)
1.869(4)
1.978(7)
1.8282(17)
1.95(1)
1.817(2)
1.8540(8)
1.970(4)
2.0087(16)
1.973(3)
2.002(4)
1.983(5)
1.911(2)
1.884(2)
2.053(5)
served.
2
[
2
[
[
[
[
[
[
[
[
[
[
[
[
[
[
Fe(salen)Cl][
49]
Co(ap)] (7)
Co(salen)][
50]
Ni(ap)] (8)
Ni(salen)][
51]
Pd(ap)] (9)
Pd(salen)][
52]
Pt(ap)] (10)
Pt(salen)][
53]
Cu(ap)py] (11)
Cu(salen)][
54][b]
Zn(ap)] (12)
Zn(salen)]
[55]
2
[
a] ap: anthraphen. [b] In the case of the copper–salen complex, no pyridine
adduct has been found in the literature and so solvent-free [Co(salen)] has
been used for comparison.
metal complexes, the cobalt and zinc atoms have a distorted
square-planar configuration, the vanadium atom has a square-
pyramidal configuration, and the iron and copper atoms have
a distorted square-pyramidal configuration.
Table 3. Torsion angles (γ) of the donor atoms O1–N1–N2–O3, positions of
the metal atom relative to the plane (Pl) formed by them, M–Laxial bond
lengths, angles α between the planes formed by C21–C26 and C1a–C4a–
C10–C5a–C8a–C9, angles ꢀ formed by C21–C26 and C11a–C14a–C20–C15a–
C18a–C19, and ionic radius of the metal cation.
Figure 5. (a) Column-like structure and (b) π stacking of [Co(anthraphen)] (7)
{
(
isostructural with [Pt(anthraphen)] (10)}, (c) π stacking of [Ni(anthraphen)]
8) and column-like structures of (d) [V(anthraphen)O] (4), (e) [Fe(anthra-
Compound[a]
(ap) (1)
V(ap)O] (4)
γ [°]
d(M···Pl) [Å]
d(M–L) [Å]
α [°], ꢀ [°] αꢀ [°]
phen)Cl] (6), (f) [Cu(anthraphen)py] (11), and (g) [Zn(anthraphen)] (12). For
clarity, hydrogen atoms and solvent molecules are not shown.
H
2
56.1
45.9
45.6
56.1
46.1
[
0.12
0.58
0.58
1.601(3)
1.606(3)
0.10
The N–M and O–M bond lengths of the metal complexes
and those of comparable literature-known salen complexes are
listed in Table 2. Comparison shows that the bond lengths are
nearly identical. Larger differences are observed for the zinc
complexes due to strong intermolecular interactions of the sol-
vent-free salen complex, which result in a binuclear complex.
Short contacts are formed between O1 and the metal center of
a second complex molecule, which result in longer O–M and N–
M bonds. Furthermore, the copper–anthraphen complex shows
shorter N–M but longer O–M distances, which can be explained
by the influence of the axial pyridine ligand and enhanced co-
ordination number.
4
45.8
7.2
[V(salen)O][48]
1.590
2.2125(16)
[Fe(ap)Cl] (6)
3.40
0.56
47.5
48.5
49.5
[
Fe(salen)Cl][49]
2.295
[Co(ap)] (7)
2.24
0.00
0.26
0.53
1.02
2.94
0.06
0.03
0.03
0.06
0.16
0.01
44.1
45.4
45.4
44.8
44.9
50.8
44.3
49.5
44.4
[
Ni(ap)] (8)
Pd(ap)] (9)
4
4.3
54.6
7.1
[
4
[Pt(ap)] (10)
Cu(ap)py] (11)
43.8
44.8
50.0
[
2.335(6)
The coordination geometries of the metal atoms can be de-
termined by comparison of the torsion angles of the donor
atoms O1–N1–N2–O3 {also O6–N3–N4–O8 for [V(anthraphen)O]
4
9.0
46.3
2.4
[Zn(ap)] (12)
4
(
4)}, the positions of the metal atom relative to the plane
formed by them, and the M–Laxial bond lengths in the case of
V(anthraphen)O] (4), [Fe(anthraphen)Cl] (6), and [Cu(anthra-
[
a] ap: anthraphen.
[
The interplanar angle α between the phenylenediamine
phen)py] (11). The relevant values are listed in Table 3. Also bridge and the carbon atoms of the quinone imine system has
listed are comparable M–Laxial bond lengths of literature-known already been discussed above for H (anthraphen) (1; Figure 3,
2
salen complexes. It is incidental that four different coordination b). The corresponding angles α and ꢀ for the metal complexes
geometries are obtained. The nickel, palladium, and platinum 4,6–12 are listed in Table 3. No distinctive trend can be identi-
8
2+
atoms have a square-planar configuration typical of low-spin d
fied between the metal complexes. On the one hand, Cu and
Eur. J. Inorg. Chem. 2016, 477–489
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Pd2+ have the largest ionic radii and their complexes show the
largest average angles. On the other hand, nickel and vanadium
have the smallest ionic radii and their complexes show me-
dium-to-high average angles. Zinc, platinum, and cobalt have
medium ionic radii and their complexes also show medium av-
[
56]
erage angles.
All in all, the interplanar angles within these
chelate complexes are significantly smaller than that of the pro-
tonated ligand. In contrast to phthalocyanine [PcM] complexes,
the title compounds [M(ap)] cannot be perfectly planar as the
aromatic hydrogen atoms C8–H and C26–H as well as C18–H
and C23–H avoid facing each other.
UV/Vis Spectroscopy
The absorption spectra of H (anthraphen) (1), [Ti(anthra-
2
phen)(NMe ) ] (3), [V(anthraphen)O] (4), [Fe(anthraphen)] (5),
2
2
[
(
Fe(anthraphen)Cl] (6), [Co(anthraphen)] (7), [Ni(anthraphen)]
8), [Pd(anthraphen)] (9), [Cu(anthraphen)] (11), and [Zn(anthra-
phen)] (12) in dichloromethane are shown in Figure 6 and their
corresponding absorption maxima and molar extinction coeffi-
cients are presented in Table 4. For the platinum (10) and potas-
sium (2) complexes no meaningful spectra could be obtained
due to their very low solubility in dichloromethane and other
common solvents.
All the compounds show their strongest absorption bands
in the short-wavelength region at 250 ± 5 nm, which is believed
to be due to a π→π* transition of the benzenoid system based
on comparison with the data of anthraquinone derivatives.[57]
A second weak absorption at 322 ± 12 nm can be found as a
Figure 6. UV/Vis spectra of H
2
2 2
(anthraphen) (1), [Ti(anthraphen)(NMe ) ] (3),
[
V(anthraphen)O] (4), [Fe(anthraphen)] (5), [Fe(anthraphen)Cl] (6), [Co(anthra-
phen)] (7), [Ni(anthraphen)] (8), [Pd(anthraphen)] (9), [Cu(anthraphen)] (11),
and [Zn(anthraphen)] (12) in dichloromethane.
shoulder for H (anthraphen) (1), [Co(anthraphen)] (7), and be due to a d→π* transition.[60] The absorption bands between
2
[
Ni(anthraphen)] (8), or as an isolated peak for [Fe(anthraphen)] 461 and 748 nm, depending on the central metal atom, can
(
5), [Pd(anthraphen)] (9), and [Cu(anthraphen)] (11), which can be explained qualitatively by d→d transitions. The electronic
[
57]
also be correlated to a benzenoid absorption.
most of the compounds show a medium-intense absorption Co
band at 291 ± 9 nm, which is believed to originate from quin- higher wavelengths.
one iminoid electron transfer. Weak quinonoid absorption is phen)] (8) is typical of a low-spin d square-planar group 10
also mentioned in the literature at 405 nm, which can be corre- complex with d→d transitions at 500 nm and a higher wave-
lated to the absorption at 435 ± 1 nm for the quinone iminoid length.[ The electronic spectrum of [Cu(anthraphen)] (11) is
Furthermore, spectrum of [Co(anthraphen)] (7), for example, is typical of a
II
7
d complex with d→d transitions at 410–490 nm and
[
60]
The UV/Vis spectrum of [Ni(anthra-
[
57]
8
61]
II
9
system. It is also known for salen derivatives that the free ligand typical of a Cu d complex with a d→d transition at around
[
18]
shows an n→π* transition in the region of 400–440 nm that 580 nm, which fits with the broad absorption between 500–
involves the promotion of a free lone-pair electron on the nitro- 600 nm. The complete assignment is hindered because of over-
gen atom to an antibonding π* orbital of the imine group.[58,59] lapping π→π* and d→π* or d→d transitions in this versatile
The absorption of [Ti(anthraphen)(NMe ) ] (3), [Ni(anthraphen)] system. It is notable that all the complexes show higher molar
2
2
(
8), and [Zn(anthraphen)] (12) in that wavelength range could extinction coefficients than the free ligand.
Table 4. Absorption data for H
Compound[a]
2
(anthraphen) (1) and its complexes 3–9, 11, and 12.
λ [nm] (ε [L mol–1 cm–1])[b]
1
2
3
4
5
6
7
8
H
2
(ap) (1)
252 (47000)
246 (49800)
250 (66400)
249 (57500)
250 (38900)
251 (61100)
252 (61700)
255 (55700)
253 (65100)
248 (63900)
282 (31100)
265 (45900)
288
325
435 (11400)
434 (11100)
[
[
[
[
[
[
[
[
[
Ti(ap)(NMe
V(ap)O] (4)
Fe(ap)] (5)
Fe(ap)Cl] (6)
Co(ap)] (7)
Ni(ap)] (8)
Pd(ap)] (9)
Cu(ap)] (11)
Zn(ap)] (12)
2 2
) ] (3)
470 (19300)
470 (16000)
473
310 (26700)
386
300
282
317
334
316 (17500)
326 (22700)
461 (15600)
504 (22200)
463 (17100)
501 (22300)
558 (13500)
553
612 (11500)
640
619 (13400)
592
435 (20200)
748
284
299
394
434 (18.900)
[a] ap: anthraphen. [b] In the case of shoulders, the approximate wavelengths of the theoretical maxima are given without molar extinction coefficients.
Eur. J. Inorg. Chem. 2016, 477–489
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482

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Figure 7 shows the UV/Vis spectra of H (anthraphen) (1), as of their low solubility. Figure 8 shows exemplarily the cyclic
2
the free ligand, [Ni(anthraphen)] (8), as the complex showing voltammogram of H (anthraphen) (1). The redox potentials
2
1
a
k
the highest molar extinction coefficients, and [Pd(anthraphen)]
9), as the complex with an absorption in the longest wave- the cyclic voltammetry experiments are summarized in Table 5;
length region for comparison. [Ni(anthraphen)] (8) shows at high-resolution graphics can be found in the Supporting Infor-
Φ
and peak separation values ΔΦ(j –j ) determined from all
rev p p
(
52 nm with ε = 61700 L mol–1 cm an extinction coefficient mation. From the peak separation values and the cathodic-to-
–1
2
nearly twice as high as that of the free ligand 1. Furthermore, anodic or anodic-to-cathodic peak current ratios, the electron-
all extinction coefficients are increased, and another absorption transfer mechanisms were estimated to be reversible, quasi-re-
maximum is evident at 504 nm with a shoulder at 553 nm along versible, or irreversible, and consist of one or multiple electron
with weak absorptions at 640 and 748 nm. The palladium com- transfers. All the compounds were investigated at different scan
plex 9 shows less of an increase in absorbance, but therefore a rates to determine the dependencies of the peak current, which
broader absorption between 463 and 619 nm. The latter could gives information about the kinetics of the processes. Thereby a
be caused by d→d transitions.
diffusion-controlled electron-transfer process can be confirmed
Figure 9).
(
Figure 8. Cyclic voltammogram of [H
2
(anthraphen)] (1) in DMSO (ca.
–
1
–1
5
mmol L ) with TBAPF (50 mmol L ) as electrolyte at a scan rate of 50
6
–
1
mV s . Potentials are plotted against the ferrocene/ferrocenium redox cou-
ple. The arrow indicates the starting point and scan direction.
Figure 7. UV/Vis spectra of H
(
[
2
(anthraphen) (1), as free ligand, [Ni(anthraphen)]
8), as the complex showing the highest molar extinction coefficients, and
Pd(anthraphen)] (9), as the complex with an absorption in the longest wave-
length region.
Complexes of salen derivatives have molar extinction coeffi-
cients of approximately 10000 L mol–1 cm ,
–1 [62]
whereas the
H (anthraphen) complexes 2–12 show molar extinction coeffi-
2
cients of up to 66400 L mol–1 cm .
–1
Cyclic Voltammetry
The redox behavior of H (anthraphen) (1), [V(anthraphen)O] (4),
2
[
(
Fe(anthraphen)Cl] (6), [Co(anthraphen)] (7), [Ni(anthraphen)]
8), [Pd(anthraphen)] (9), [Cu(anthraphen)] (11), and [Zn(anthra-
phen)] (12) was investigated by cyclic voltammetry. [K (anthra-
2
phen)] (2), [Ti(anthraphen)(NMe ) ] (3), [Fe(anthraphen)] (5),
2
2
Figure 9. Cyclic voltammograms of [Co(anthraphen)] (7) recorded at different
and [Pt(anthraphen)] (10) could not be investigated because
scan rates.
Table 5. Redox potentials Φ r1 ev vs. FcH and peak separation values ΔΦ(j –j ) in DMSO with TBAPF as electrolyte.[a]
a
k
p
p
6
Compound[b]
Φ
rev [V] {ΔΦ(j –j ) [mV]}
a
p
k
p
1
2
3
4
5
H
2
(ap) (1)
–1.81 {91}
0.24 {88}
–1.91 {89}
–0.78
–2.24 {60}
–0.97 {110}
–2.36 {60}
–1.30 {72}
[
[
[
[
[
[
[
V(ap)O] (4)
Fe(ap)Cl] (6)
Co(ap)] (7)
Ni(ap)] (8)
Pd(ap)] (9)
Cu(ap)] (11)
Zn(ap)] (12)
–1.97 {73}
–0.58 {111}
–0.28 {160}
–1.95 {130}
–0.95 {109}
–0.88 {90}
–1.38 {111}
–1.18 {140}
–1.09 {131}
–2.53 {150}
–1.19 {119}
–1.39 {70}
–1.63 {111}
–1.22 {119}
–2.91 {140}
–1.75 {109}
–1.68 {69}
–1.88 {110}
–1.71 {130}
–2.28 {130}
–2.08 {111}
–2.13 {80}
–2.08 {140}
[
a] All potentials represent a one-electron redox event. [b] ap: anthraphen.
Eur. J. Inorg. Chem. 2016, 477–489
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Scheme 3. Schematic illustration of four ligand-centered reduction and one metal-centered oxidation processes.
The ligand, H (anthraphen) (1), shows two times, two super-
[Ni(anthraphen)] (8) shows two reversible redox processes
imposed reversible charge transfers (–1.81, –1.91, –2.24, (–2.53, –2.91 V) and one quasi-reversible process (–1.95 V).
2.36 V). It is notable that the ligand is able to take up reversi- Weak processes also occur at voltages in the range –0.5 to
2
–
bly four electrons without decomposition. The overlapping re- –1.5 V (vs. FcH) that cannot be explained. However, after a few
dox processes can be explained by the structure of the ligand. cycles, the cyclic voltammogram seems to be identical to the
As proven by the crystal structure, the two anthraquinone imine first cycle. [Pd(anthraphen)] (9) and [Cu(anthraphen)] (11) show
units are not perfectly conjugated through the phenylenedi- four reversible reduction processes (Pd: –0.95, –1.19, –1.75,
amine bridge. As a consequence, electronically, two relatively –2.08 V; Cu: –0.88, –1.39, –1.68, –2.13 V) whereas [Zn(anthra-
independent and equal π-conjugated systems exist. The system phen)] (12) shows three reversible and one quasi-reversible re-
will change its conformation on taking up one electron and so duction processes (–1.38, –1.63, –1.88, –2.08 V).
a small shift is observed for the take-up of the second electron
(
Figure 8). The cyclic voltammogram of [V(anthraphen)O] (4)
shows four reversible redox processes (0.24, –0.97, –1.30,
1.97 V) and one quasi-reversible charge transfer (–0.78 V). It
Conclusions
–
can be assumed that the missing reduction process of the H2(anthraphen) (1), a novel bis-1-hydroxy-9,10-anthraquinone-
quasi-reversible charge transfer is overlapped by the redox imine-type non-innocent chromophore ligand with a manifold
process at –0.97 V, which could explain the high peak separa- of fully reversible redox properties, has been developed. It has
tion of 110 mV compared with the other four processes a distinct coordination capacity for four equatorial positions in
(
80 ± 8 mV). [Fe(anthraphen)Cl] (6) shows two reversible proc- square planar, tetragonal pyramidal, or octahedral complexes
esses (–0.58, –1.18 V) and two broad peaks. This observation without showing the enhanced backbone flexibility of related
2
–
can be explained by the poor solubility of 6, which resulted in N O ligands such as H (salen) and H (salphen). In its coordi-
2
2
2
2
residual solid in the sample. All further samples were filtered nation chemistry, high molar extinction coefficients, and elec-
through a 0.45 μm Teflon syringe filter before measurement. trochemical properties, 1 seems to be more related to the huge
[Co(anthraphen)] (7) shows two reversible (–1.71, –2.28 V), two class of phthalocyanines (26000 publications to date). The pro-
overlapped reversible (–1.09, –1.22 V), and one quasi-reversible tonated ligand 1, the potassium salt 2, and 10 3d, 4d, and 5d
IV
IV
II
III
redox process (–0.28 V). A clear localization of the redox events transition-metal complexes, namely Ti (3), V (4), Fe (5), Fe
II
II
II
II
II
II
within the structure could not be achieved. The supposed struc- (6), Co (7), Ni (8), Cu (9), Pd (10), Pt (11), and Zn (12), have
tures of four ligand-centered reduction and one metal-centered been characterized by NMR, UV/Vis, and IR spectroscopy, cyclic
oxidation processes are illustrated in Scheme 3. In the case of voltammetry, elemental analysis, and single-crystal XRD. The
II
III
the cobalt complex 7, a nonligand-centered Co to Co oxida- optical analysis of ligand 1 revealed extinction coefficients of
tion at –0.28 V was estimated based on a comparison with up to 47000 L mol– cm (at 252 nm) and absorption bands up
1
–1
[
63,64]
Co(salen) complexes.
The comparisons also indicate that to 500 nm, whereas the corresponding complexes show higher
the metal complexes 4, 6–9, 11, and 12 of H (anthraphen) (1) extinction coefficients and a broader absorption spectrum in
2
show high stability against reduction and oxidation. Up to four the lower-energy range of visible light, for example, molar ex-
tinction coefficients of up to 66400 L mol– cm (at 250 nm) in
1
–1
electrons can be taken up and released reversibly.
Eur. J. Inorg. Chem. 2016, 477–489
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the case of [V(anthraphen)O] (4) and broadening of the absorp- SHELXL-2014[75] for refinement, and Platon[76] for final validation.
Absorption corrections (multiscan) were either applied within
tion spectrum in the visible-light region with a maximum at
[
77]
[78]
WinGX
or beforehand within the APEX2 software.
Graphics
619 nm in case of [Pd(anthraphen)] (10). Ligand 1 shows four
[
79]
were created with Diamond 3
and the ellipsoids are shown at
reversible reduction processes in cyclic voltammetry measure-
ments, whereas some of its complexes show five reversible oxi-
dation and reduction events, including metal-centered redox
activity. The comparison with salphen-type complexes showed
the 50 % probability level. Hydrogen atoms were constrained to the
parent site if carbon-bonded and independently isotropically re-
fined if located in the Fourier map and oxygen-bonded. For clarity,
hydrogen atoms are only shown if oxygen-bonded. CCDC 1423992
(for 6), 1423993 (for 12), 1423994 (for 8), 1423995 (for 11), 1423996
that H (anthraphen) (1) and its complexes 2–12 have much
2
higher molar extinction coefficients and greater stability with (for 10), 1423997 (for 7), 1423998 (for 4), 1423999 (for 1), and
respect to multiple electron uptake. The simple modular syn- 1424000 (for 9) contain the supplementary crystallographic data for
thetic approach followed in this work allows for the design of this paper. These data can be obtained free of charge from The
Cambridge Crystallographic Data Centre. UV/Vis spectra were re-
numerous variants of this chelating anthraquinone imine ligand
corded with an AvaLight-DHc light source and an AvaSpec-2048
motif. Theoretical calculations, EPR spectroscopy, and spectro-
detector using fused quartz cuvettes and dichloromethane as sol-
electrochemical studies will contribute to the tuning and un-
vent. The ligand 1 and cobalt and nickel complexes 7 and 8, respec-
derstanding of the complex absorption behavior of this inter-
tively, were additionally analyzed in tetrahydrofuran, and identical
esting class of new chromophore complexes. We believe that
spectra were obtained. UV/Vis spectra were recorded for all
metal complexes of this ligand motif will be further investigated
as effective redox, electro-, and Lewis acid catalysts, as biomi-
compounds at different concentrations in the range of 5 to
–1
2
0 μmol L to calculate their molar extinction coefficients by using
metic models for metalloenzymes, as “black dye“ sensitizers for the Beer–Lambert law. Cyclic voltammetry was carried out with an
wide-band-gap semiconductors, for example, in dye-sensitized Ivium Technologies Iviumstat or a Metrohm Autolab PGSTAT204 in-
solar cells, as well as for other optoelectronic applications.
strument using a RHD Instruments microcell HC under nitrogen at
5 °C. A glassy carbon working electrode (diameter d = 3 mm) and
2
a platinum counter electrode were used. The measurements were
carried out against a platinum pseudo-electrode or a silver/silver
sulfide reference electrode and were calibrated by adding ferrocene
as an internal standard after recording the first series of CVs. Di-
methyl sulfoxide (≥99.9 %) from Sigma–Aldrich was used as solvent
and was stored over 4 Å molecular sieves and distilled before use.
Experimental Section
General: All reactions, with the exception of the synthesis of 1-
acetoxy-9,10-anthraquinone (17), were carried out under an inert
atmosphere using standard Schlenk and glovebox techniques.
Chemicals were used as received unless stated otherwise. All sol-
vents were dried and purified according to common procedures
Tetrabutylammonium hexafluorophosphate (TBAPF ; ≥99.0 %) from
6
Fluka was used as electrolyte for electrochemical analysis. All
[
65]
[66]
and stored over 3 or 4 Å molecular sieves.
[Fe(hmds) (thf)],
–1
2
measurements were carried out at a concentration of 50 mmol L
of electrolyte and 5–10 mmol L of sample.
[67]
[68]
[69]
[
Co(hmds) (thf)],
[{PtCl(C H )}(μ-Cl)] ,
[Zn(hmds)2],
and
–1
2
2
4
2
K(hmds) were synthesized according to literature procedures. It
1
9
(
-Acetoxy-9,10-anthraquinone (17): A suspension of 1-hydroxy-
,10-anthraquinone (16; 12.3 g, 54.9 mmol) and sodium acetate
50.2 mg, 0.612 mmol) in acetic anhydride (80.0 mL, 846 mmol) was
should be mentioned that H (anthraphen) (1) never completely dis-
2
solved in the corresponding solvent in complexation reactions be-
cause of its low solubility. The anthraquinones and anthrones are
numbered according to IUPAC rules. TLC plates from Merck KGaA
with silica gel 60 on aluminium with fluorescence quenching F254
at room temperature were used for TLC. NMR spectra were recorded
in automation or by the service department (FB Chemie, Philipps
Universität Marburg) with a Bruker Avance 300, 400, or 500 spec-
trometer at 25 °C using CD Cl or CDCl as solvent and for calibra-
heated at reflux for 16 h. The orange reaction mixture was
quenched with distilled water (300 mL) and stirred for 5 min at
room temperature. The precipitate was filtered off, washed with
distilled water (3 × 30 mL), and dried in vacuo. 1-Acetoxy-9,10-
anthraquinone (17; 14.3 g, 98 %) was obtained as a yellow solid.
1
R = 0.39 (n-pentane/ethyl acetate, 20:1). H NMR (CDCl , TMS,
f
3
2
2
3
3
4
[
70]
300 MHz; pt: pseudo triplet): δ = 8.27 (dd, JH,H = 7.8, JH,H = 1.4 Hz,
H, 4-H), 8.24–8.19 (m, 2 H, 5-H, 8-H), 7.78 (pt, J = 7.9 Hz, 1 H,
tion.
ESI and APCI high-resolution mass spectra were recorded
3
1
3
1
H,H
by the service department (FB Chemie, Philipps Universität Mar-
burg) with a Finnigan LTQ-FT spectrometer using methanol or di-
chloromethane as solvent. The m/z values are given together with
their relative intensities. IR spectra were recorded with a Bruker Al-
pha FT-IR spectrometer with Platinum ATR sampling. Elemental
analyses were performed by the service department (FB Chemie,
Philipps Universität Marburg) with an Elementar vario MICRO CUBE
instrument. TGA and DSC measurements were carried out with a
Netzsch STA 409 CD instrument in aluminium oxide crucibles at a
3
4
-H), 7.77–7.74 (m, 2 H, 7-H, 6-H), 7.41 (dd, J = 8.0, J = 1.3 Hz,
H,H
H,H
H, 2-H), 2.49 (s, 3 H, 12-H) ppm. 13C NMR (CDCl , TMS, 75 MHz):
3
δ = 182.5 (C-10), 181.9 (C-9), 169.7 (C-11), 150.4 (C-1), 135.4 (C-4a),
35.0 (C-3), 134.4 (C-7), 134.2 (C-8a), 134.1 (C-6), 132.8 (C-5a), 130.0
C-2), 127.3 (C-8), 127.1 (C-5), 125.9 (C-4), 125.0 (C-1a), 21.3 (C-
1
(
1
2) ppm. IR (neat): ν˜ = 2361 (w), 1764 (s, C=O) 1672 (s, C=O), 1589
(
(
m), 1442 (w), 1362 (w), 1323 (m), 1278 (s), 1239 (w), 1182 (s), 1165
m, C–O), 1041 (w), 1020 (w), 995 (w), 970 (w), 899 (m), 861 (m), 808
–
1
–1
(s), 777 (w), 731 (m), 704 (s), 688 (s), 652 (m), 582 (m), 543 (m), 530
heating rate of 5 K min and an argon flow rate of 40 mL min .
TGA decomposition points are given as the onset temperature and
DSC data are given as the peak value. Single-crystal structure deter-
mination was performed by XRD by the service department (FB
Chemie, Philipps Universität Marburg) with a Bruker D8 Quest or
Stoe IPDS-II diffractometer at 100 K using Mo-Kα radiation (λ =
–
1
(
2
m), 483 (m), 452 (w), 410 (w) cm . MS (ESI+, CH Cl ): m/z (%) =
2 2
+
89.1 (100). HRMS: calcd. for [M + Na] 289.0471; found 289.0471.
C H O (266.25): calcd. C72.18, H 3.79; found C 72.23, H 3.71.
16 10 4
1-Hydroxy-9,9-dimethoxy-10-anthrone (18): A solution of so-
dium methoxide (4.64 g, 85.9 mmol) in methanol (40 mL) was
slowly added to a suspension of 1-acetoxy-9,10-anthraquinone (17;
0
.71073 Å). Stoe (X-AREA, X-RED) or Bruker (Instrument Service,
APEX2, SAINT) software were used for data collection, cell refine- 6.50 g, 24.4 mmol) in tetrahydrofuran (210 mL) and the resulting
[
71,72]
[73]
ment, and data reduction.
The WinGX
program suite using
mixture was stirred for 30 min at room temperature. The dark-red
SIR-97[
74]
or SHELXT-2014
[75]
was used for structure solution, reaction mixture was quenched with distilled water (280 mL) and
Eur. J. Inorg. Chem. 2016, 477–489
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Full Paper
acetic acid was added until the color changed to yellow. Afterwards,
distilled water (560 mL) was added and the yellow precipitate was
filtered off and washed with distilled water (3 × 100 mL). The raw
[Ti(anthraphen)(NMe ) ] (3): Tetrakis(dimethylamido)titanium
2
2
(50.0 μL, 0.214 mmol) was added to a suspension of H (anthraphen)
2
(1; 104 mg, 0.201 mmol) in toluene (18 mL) and the resulting mix-
product was purified by column chromatography [deactivated (tri- ture was heated at reflux for 30 min. All the volatile components
ethylamine/n-pentane) silica gel; n-pentane/ethyl acetate, 20:1] and
dried in vacuo. 1-Hydroxy-9,9-dimethoxy-10-anthrone (18; 4.57 g,
were removed in vacuo. [Ti(anthraphen)(NMe ) ] (3; 112 mg, 86 %)
2 2
1
was obtained as a green-black solid. H NMR (CD Cl , TMS, 300 MHz;
2
2
3
6
9 %) was obtained as a yellow solid. R = 0.48 (n-pentane/ethyl
pt: pseudo triplet): δ = 8.31 (d,
J
= 8.5 Hz, 2 H, H ), 7.95 (d,
f
H,H
3
ar
1
3
4
acetate, 20:1). H NMR (CD Cl , TMS, 300 MHz; pt: pseudo triplet):
δ = 8.27 (dd, J = 7.9, J = 0.9 Hz, 1 H, 5-H), 8.03 (s, 1 H, OH),
JH,H = 8.9 Hz, 2 H, H ), 7.90 (dd, J
= 8.9, J
= 1.1 Hz, 2 H,
2
2
ar
H,H
H,H
3
4
3
H ), 7.41 (pt, J = 7.9 Hz, 2 H, H ), 7.27–7.14 (m, 4 H, H ), 6.76
(dd, J = 7.2, J = 0.9 Hz, 2 H, H ), 6.24 (dd, J = 6.0, J
H,H
H,H
ar
H,H
4
ar
ar
4
3
4
3
3
3
7
.85 (dd, J = 7.8, J = 1.2 Hz, 1 H, 4-H), 7.84 (dd, J = 7.7,
=
H,H
H,H
H,H
H,H
H,H
ar
H,H
H,H
4
3
4
3
4
JH,H = 1.1 Hz, 1 H, 8-H), 7.79 (ddd, J = 7.8, 7.2, J = 1.4 Hz, 1
3.4 Hz, 2 H, H ), 6.24 (dd, J = 5.9, J = 3.4 Hz, 2 H, H ), 3.30
H,H
H,H
ar H,H H,H ar
3
4
13
H, 7-H), 7.62 (ddd, J = 7.9, 7.2, J = 1.4 Hz, 1 H, 6-H), 7.49 (pt,
[s, 12 H, 2 N(CH ) ] ppm. C NMR: too poorly soluble in common
H,H
H,H
3 2
3
3
4
JH,H = 7.9 Hz, 1 H, 3-H), 7.21 (dd, J = 8.1, J = 1.1 Hz, 1 H, 2-
solvents. IR: ν˜ = 2839 (w, br), 2766 (w, br), 1580 (w), 1547 (w), 1512
H,H
H,H
1
3
H), 2.96 (s, 6 H, 2 OCH ) ppm. C NMR (CD Cl , TMS, 75 MHz): δ = (w), 1461 (m), 1438 (m), 1370 (s), 1300 (s), 1250 (s), 1185 (w), 1151
3
2
2
1
82.4 (C-10), 156.4 (C-1), 138.6 (C-8a), 134.8 (C-4a), 134.7 (C-7), 133.8
(w), 1115 (w), 1055 (w), 1024 (m), 1004 (s), 646 (w), 756 (m), 729 (m),
713 (m), 687 (m), 663 (m), 645 (m), 609 (m), 576 (m), 553 (m) cm .
–1
(C-5a), 131.6 (C-3), 130.4 (C-6), 127.3 (C-5), 127.1 (C-8), 122.6 (C-2, C-
1
2
a), 119.3 (C-4), 100.2 (C-9), 52.3 (2 OCH ) ppm. IR: ν˜ = 3393 (w, br),
MS (APCI+, CH OH): m/z (%) = 597.2 (25). HRMS: calcd. for
3
3
+
998 (w), 2931 (w), 2828 (w), 1671 (m), 1638 (w), 1593 (m), 1452
[C H N O Ti + CH O] 597.0928; found 597.0922.
34
18
2
4
3
(
(
m), 1317 (m), 1272 (s), 1252 (s), 1223 (m), 1199 (m), 1157 (m), 1065
[
0
V(anthraphen)O] (4): A suspension of H (anthraphen) (1; 98 mg,
2
.19 mmol) and vanadyl acetylacetonate (52 mg, 0.20 mmol) in tolu-
–
1
s), 998 (s), 872 (m), 830 (w), 767 (s), 707 (m) cm . MS (ESI+, CH OH):
3
+
m/z (%) = 293.1 (100). HRMS: calcd. for [M + Na] 293.0784; found
2
ene (15 mL) was heated at reflux for 18 h. Afterwards, the reaction
mixture was filtered, washed with toluene (2 × 2 mL), and dried in
vacuo. [V(Anthraphen)O] (4; 94 mg, 86 %) was obtained as a red
solid. IR: ν˜ = 1666 (s), 1581 (s), 1553 (w), 1504 (s), 1472 (w), 1452
93.0788.
H (anthraphen) (1): A solution of 1-hydroxy-9,9-dimethoxy-10-
anthrone (18; 8.37 g, 31.0 mmol) and o-phenylenediamine (1.68 g,
2
(w), 1415 (m), 1361 (m), 1339 (w), 1305 (m), 1265 (s), 1242 (m), 1222
1
5.5 mmol) in toluene (250 mL) was heated at reflux for 24 h, cooled
to –30 °C, and filtered. The solid was washed with cold toluene (2 ×
0 mL) and purified by column chromatography (silica gel, CHCl3).
H (anthraphen) (1; 5.85 g, 72 %) was obtained as a red solid. R =
(m), 1157 (m), 1145 (w), 1024 (w), 978 (s), 894 (m), 831 (m), 799 (w),
–
1
7
79 (m), 748 (m), 712 (s), 703 (s), 662 (w), 543 (m) cm . MS (APCI+,
2
+
CH OH): m/z (%) = 585.3 (50), 586.3 (100). HRMS: calcd. for [M]
585.0650; found 585.0649; calcd. for [M + H] 586.0728; found
586.0731. C H N O V (585.46): calcd. C 69.75, H 3.10, N 4.78; found
C 69.04, H 3.01, N 5.15.
3
2
f
+
1
0
1
.18 (CHCl ). H NMR (CDCl , TMS, 300 MHz; pt: pseudo triplet): δ =
3.40 (s, 2 H, OH), 8.08 (dd, JH,H = 8.2, J = 1.5 Hz, 2 H, 5-H, 15-
3 3
3
4
34 18 2 5
H,H
H), 7.63–7.58 (m, 6 H, 4-H, 14-H, 6-H, 16-H, 8-H, 18-H), 7.46 (pt,
3
JH,H = 7.92 Hz, 2 H, 3-H, 13-H), 7.39–7.34 (m, 4 H, 7-H, 17-H, 23-H,
[Fe(anthraphen)] (5): A solution of [Fe(hmds) (thf)] (159 mg, 0.354)
in tetrahydrofuran (10 mL) was added to a suspension of H (anthra-
phen) (1; 183 mg, 0.352 mmol) in tetrahydrofuran (20 mL) and the
resulting mixture was heated at reflux for 30 min. The reaction mix-
ture was filtered, washed with hot n-hexane, and dried in vacuo.
2
3
4
2
1
1
6-H), 7.28–7.23 (m, 2 H, 24-H, 25-H), 7.03 (dd, J
= 8.2, J
=
H,H
H,H
2
1
3
.1 Hz, 2 H, 2-H/, 12-H) ppm. C NMR (CDCl , TMS, 75 MHz): δ =
3
81.5 (C-10, C-20), 162.1 (C-9, C-19), 161.0 (C-1, C-11), 136.6 (C-21,
C-22), 133.8 (C-3, C-13), 132.9 (C-6, C-16), 132.7 (C-5a, C-15a), 132.6
C-7, C-17), 131.6 (C-4a, C-14a), 130.1 (C-8a, C-18a), 128.0 (C-5, C-
(
1
2
[Fe(anthraphen)] (5; 189 mg, 93 %) was obtained as a black solid.
5), 127.3 (C-8, C-18), 126.9 (C-23, C-26), 123.8 (C-2, C-12), 122.5 (C-
4, C-25), 118.9 (C-4, C-14), 117.7 (C-1a, C-11a) ppm. IR: ν˜ = 1665
IR: ν˜ = 1657 (s), 1616 (m), 1567 (s), 1531 (m), 1472 (s), 1427 (w),
1
1
8
6
6
413 (m), 1351 (s), 1301 (s), 1261 (s), 1238 (w), 1218 (s), 1152 (m),
139 (w), 1107 (w), 1072 (w), 1041 (w), 1022 (m), 930 (w), 883 (m),
(
(
(
(
(
(
s), 1588 (s), 1552 (m), 1487 (m), 1450 (s), 1344 (m), 1318 (m), 1288
s), 1270 (s), 1225 (s), 1155 (m), 1143 (m), 1111 (m), 1094 (w), 1069
w), 1047 (w), 1035 (w), 1014 (m), 963 (w), 882 (m), 848 (m), 829
m), 784 (s), 776 (s), 765 (s), 726 (w), 709 (s), 697 (s), 656 (m), 618
w), 553 (w), 536 (w), 524 (w), 488 (w), 470 (m), 435 (w) cm . MS
APCI+, CH OH): m/z (%) = 521.3 (100). HRMS: calcd. for [M + H]
26 (m), 791 (m), 770 (s), 740 (s), 706 (s), 663 (w), 651 (w), 633 (w),
–1
10 (w), 497 (m) cm . MS (APCI+, CH OH): m/z (%) = 574.1 (100),
3
+
05.4 (75). HRMS: calcd. for [M] 574.0611; found 574.0610; calcd.
–
1
+
for [M + CH OH] 606.0872; found 606.0869. C H N O Fe·C H O
(646.47): calcd. C 70.60, H 4.05, N 4.33; found C 70.65, H 4.21, N
4.45.
3
34 18
2
4
4 8
+
3
5
3
21.1496; found 521.1496. C H N O (520.53): calcd. C 78.45, H
34 20 2 4
.87, N 5.38; found C 78.21, H 3.92, N 5.20. TGA: 297 °C (decomp.);
[
0
Fe(anthraphen)Cl] (6):
A solution of K(hmds) (103 mg,
DSC: 296 (endoth.), 300 (exoth.) °C.
.516 mmol) in toluene (5 mL) was added to a suspension of H2
[
K (anthraphen)(thf) ] (2): A suspension of potassium hydride
(anthraphen) (1; 126 mg, 0.242 mmol) in toluene (10 mL) and the
resulting mixture was heated at reflux for 30 min. The dark-red
precipitate was filtered, washed with toluene (2 × 10 mL), and sus-
pended in tetrahydrofuran (20 mL). A solution of FeCl3 (39 mg,
0.24 mmol) in tetrahydrofuran (5 mL) was added and the resulting
suspension was heated at reflux for 1 h. The reaction mixture was
concentrated to a few milliliters and then n-pentane was added
2
2
(7.7 mg, 0.019 mmol) in tetrahydrofuran (2 mL) was added to a
suspension of H (anthraphen) (1; 50 mg, 0.096 mmol) in tetrahydro-
2
furan, (8 mL) and the resulting mixture was stirred for 1 h at room
temperature. After concentrating the solution to a few milliliters,
the precipitate was filtered off and washed with tetrahydrofuran
(2 × 2 mL). [K (anthraphen)]·THF (2; 33 mg, 58 %) was obtained as
2
a violet-black solid. IR: ν˜ = 2962 (w, br), 1645 (m), 1586 (w), 1566 until precipitation occurred. The precipitate was filtered off, washed
(m), 1515 (m), 1449 (m), 1409 (m), 1369 (w), 1336 (w), 1296 (m), with methanol (2 × 5 mL), and dried in vacuo. [Fe(anthraphen)Cl]
1
7
5
258 (s), 1207 (w), 1154 (w), 1089 (m), 1016 (s br), 921 (w), 883 (m), (6; 107 mg, 72 %) was obtained as a brown-black solid. IR: ν˜ = 1665
96 (s), 774 (s), 748 (m), 705 (s), 661 (m), 615 (w), 597 (w), (s), 1581 (s), 1510 (s), 1472 (w), 1446 (w), 1418 (w), 1301 (s), 1264
47 (w), 529 (w), 513 (w), 469 (w), 446 (w), 435 (w) cm . (s), 1241 (m), 1225 (m), 1158 (w), 1143 (w), 1108 (w), 1074 (w), 1044
(w), 1021 (m), 892 (m), 829 (m), 777 (m), 751 (m), 735 (m), 709 (s),
–
1
C H K N O ·2C H O (668.82): calcd. C 68.08, H 4.63, N 3.78; found
C 68.01, H 4.66, N 4.21.
34
18
2
2
4
4 8
–
1
662 (w), 548 (w), 498 (w) cm . MS (APCI+, CH Cl ): m/z (%) = 574.2
2 2
Eur. J. Inorg. Chem. 2016, 477–489
www.eurjic.org
486
© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Full Paper
(
100). HRMS: calcd. for [M – Cl]+ 574.0611; found 574.0606. 1492 (m), 1468 (m), 1445 (w), 1399 (w), 1357 (m), 1299 (s), 1258 (s),
C H N O FeCl·0.5C H O (645.87): calcd. C 66.95, H 3.43, N 4.34;
found C 66.92, H 3.45, N 4.37.
1236 (m), 1212 (s), 1166 (w), 1136 (m), 1076 (w), 1032 (m), 1024 (m),
969 (w), 893 (w), 825 (w), 766 (s), 731 (w), 716 (m), 702 (s), 681 (w),
34
18
2
4
4 8
–
1
6
52 (w), 547 (w), 525 (w), 513 (w) cm . MS (APCI+, CH Cl ): m/z
2 2
[
Co(anthraphen)] (7): A solution of [Co(hmds) (thf)] (93 mg,
2
+
(%) = 625.22 (85). HRMS: calcd. for [M + H] 625.0387; found
0
.24 mmol) in toluene (9 mL) was added to a suspension of H2
6
4
25.0367. C H N O Pd·CH OH (656.98): calcd. C 63.99, H 3.38, N
.26; found C 63.79, H 3.30, N 4.42.
34 18 2 4 3
(anthraphen) (1; 121 mg, 0.233 mmol) in toluene (15 mL) and the
resulting mixture was heated at reflux for 2.5 h. The reaction mix-
ture was filtered, washed with cold toluene (2 × 3 mL), and dried
in vacuo. [Co(anthraphen)] (7; 122 mg, 91 %) was obtained as a
black solid. IR: ν˜ = 1663 (m), 1645 (s), 1578 (s), 1536 (w), 1480 (m),
[Pt(anthraphen)] (10): A suspension of H (anthraphen) (1; 150 mg,
2
0.288 mmol) and sodium acetate (49 mg, 0.60 mmol) in dimethyl-
formamide (10 mL) was stirred for 15 min at room temperature.
Afterwards, a solution of [{PtCl(C H )}(μ-Cl)] (232 mg, 0.394 mmol)
1
466 (m), 1448 (w), 1407 (m), 1369 (m), 1350 (m), 1327 (w), 1302
2
4
2
(
(
8
6
s), 1266 (s), 1242 (m), 1230 (m), 1183 (w), 1170 (w), 1154 (m), 1143 in dimethylformamide (10 mL) was added and the resulting suspen-
m), 1111 (w), 1075 (w), 1027 (w), 983 (w), 965 (w), 945 (w), 893 (w),
83 (w), 825 (w), 809 (w), 777 (s), 761 (s), 734 (s), 717 (w), 701 (s),
sion was heated at 110 °C for 4 d. The reaction mixture was filtered,
the solvent was removed from the filtrate in vacuo, and the residue
62 (w), 651 (w), 620 (w), 591 (w), 561 (w), 545 (w), 534 (w), 514 was recrystallized from chloroform. [Pt(anthraphen)] (10; 42 mg,
–
1
1
(
(
w), 465 (w), 432 (w) cm . MS (APCI+, CH Cl ): m/z (%) = 578.17
20 %) was obtained as a black solid. H NMR (CDCl , TMS, 400 MHz;
2
2
3
100). HRMS: calcd. for [M + H]+ 578.0671; found 578.0672.
pt: pseudo triplet): δ = 8.31 (dd, J = 7.6, J = 1.0 Hz, 2 H, H ),
H,H H,H Ar
3
4
3
3
4
C H N O Co·C H (668.58): calcd. C 73.54, H 3.91, N 4.18, Co 8.80; 7.96 (d, J = 8.0 Hz, 2 H, H ), 7.89 (dd, J = 6.62, J = 1.73 Hz,
found C 73.84, H 3.82, N 4.77, Co 8.53.
34
18
2
4
7
8
H,H
Ar
H,H
H,H
3
2 H, H ), 7.76 (pt, J = 7.7 Hz, 2 H, H ), 7.70–7.53 (m, 6 H, H ),
Ar H,H Ar Ar
3
4
3
6
6
1
1
.91 (dd, J = 6.6, J = 3.5 Hz, 2 H, 24-H, 25-H), 6.66 (dd, J
.4, JH,H = 3.4 Hz, 2 H, 23-H, 26-H) ppm. C NMR (CDCl , TMS,
00 MHz): δ = 184.1 (C-10, C-20), 165.0, 157.1 (C-1, C-11, C-9, C-19),
49.1 (C-21, C-22), 133.6 (2 C ), 133.4, 133.2, 132.5, 132.1, 131.5 (10
=
H,H
H,H
H,H
[
0
Ni(anthraphen)] (8): A solution of [Ni(OAc) ·4H O] (99 mg,
.40 mmol) in methanol (4 mL) was added to a suspension of H2
2 2
4
13
3
(anthraphen) (1; 189 mg, 0.363 mmol) in methanol (20 mL) and the
q
resulting mixture was heated at reflux for 3.5 h. The reaction mix-
ture was filtered at +4 °C, washed with cold methanol, and dried in
vacuo. [Ni(anthraphen)] (8; 185 mg, 88 %) was obtained as a black
C ), 130.9, 130.2 (4 C ), 128.3 (2 C ), 126.0 (C-23, C-26), 125.5 (C-
Ar
q
Ar
2
4, C-25), 123.1 (2 C ), 120.4 (2 C ) ppm. IR: ν˜ = 2962 (w), 2923
q
Ar
(w), 2852 (w), 2402 (w), 2382 (m), 2363 (w), 2350 (m), 2336 (m),
1
3
solid. H NMR (CD Cl , TMS, 300 MHz): δ = 8.27 (dd, JH,H = 7.8,
2
2
2327 (m), 2306 (w), 2293 (w), 2251 (w), 1665 (m), 1584 (m), 1493
4
3
JH,H = 1.2 Hz, 2 H, 5-H, 15-H), 8.01 (d, J = 7.7 Hz, 2 H, 8-H, 18-
H,H
(
(
7
w), 1469 (w), 1451 (w), 1405 (w), 1366 (w), 1305 (w), 1260 (s), 1139
3
4
H), 7.72 (ddd, J
= 7.7, 7.4, J
= 1.1 Hz, 2 H, 6-H, 16-H), 7.69
H,H
H,H
w), 1092 (w), 1016 (m), 910 (w), 863 (w), 796 (s), 753 (w), 724 (m),
3
4
3
(dd, J = 7.0, J = 1.2 Hz, 2 H, 4-H, 14-H), 7.58 (ddd, J = 8.1,
H,H H,H H,H
–1
04 (m), 674 (s), 662 (s) cm . MS (APCI+, CH OH): m/z (%) = 714.3
4
3
3
7
3
6
.3, J = 1.5 Hz, 2 H, 7-H, 17-H), 7.44 (dd, J = 8.6, 7.1 Hz, 2 H,
H,H H,H
+
(
100). HRMS: calcd. for [M + H] 714.0990; found 714.0980.
3
4
-H, 13-H), 7.32 (dd, JH,H = 8.6, J = 1.3 Hz, 2 H, 2-H, 12-H), 6.73–
.68 (m, 2 H, 24-H, 25-H), 6.64–6.59 (m, 2 H, 23-H, 26-H) ppm.
H,H
13
C
[Cu(anthraphen)] (11): A solution of [Cu(OAc) ·H O] (69 mg,
2 2
NMR (CD Cl , TMS, 75 MHz): δ = 183.4 (C-10, C-20), 165.2 (C-1, C- 0.35 mmol) in methanol (4 mL) was added to a suspension of H (an-
2
2
2
1
1), 162.5 (C-9, C-19), 148.1 (C-21, C-22), 134.0 (C-5a, C-15a), 133.9
thraphen) (1; 181 mg, 0.348 mmol) in tetrahydrofuran (20 mL) and
(C-3, C-13), 133.0 (C-6, C-16), 132.3 (C-7, C-17), 132.0 (C-8a, C-18a),
the resulting suspension was heated at reflux for 3.5 h. The black
1
31.8 (C-4a, C-14a), 131.3 (C-8, C-18), 129.5 (C-2, C-12), 128.2 (C-5, reaction mixture was filtered at +4 °C, washed with cold methanol,
C-15), 126.0 (C-23, C-26), 124.8 (C-24, C-25), 122.2 (C-1a, C-11a),
and dried in vacuo. [Cu(anthraphen)] (11; 171 mg, 85 %) was ob-
1
18.2 (C-4, C-14) ppm. IR: ν˜ = 1651 (m), 1579 (s), 1492 (m), 1468 tained as a black solid. IR: ν˜ = 1663 (m), 1581 (s), 1501 (s), 1474 (s),
(m), 1450 (w), 1404 (m), 1369 (m), 1301 (s), 1264 (s), 1229 (s), 1169
1406 (s), 1355 (s), 1303 (s), 1261 (s), 1247 (s), 1220 (s), 1157 (m),
1140 (m), 1110 (m), 1073 (m), 1046 (m), 1025 (m), 888 (m), 828 (m),
801 (w), 782 (m), 772 (s), 753 (s), 741 (m), 710 (s), 696 (s), 657 (m),
(w), 1141 (m), 1076 (w), 1030 (m), 899 (w), 827 (w), 788 (w), 768 (s),
–
1
7
50 (w), 734 (w), 723 (w), 703 (s), 687 (w), 653 (w), 544 (w) cm .
+
–1
MS (APCI+, CH Cl ): m/z (%) = 577.2 (65). HRMS: calcd. for [M + H]
543 (s), 522 (s) cm . MS (APCI+, CH Cl ): m/z (%) = 582.2 (100).
2
2
2
2
+
5
6
77.0693; found 577.0693. C H N O Ni·CH OH (609.25): calcd. C
HRMS: calcd. for [M + H] 582.0635; found 582.0635. C H N O Cu
3
4
18
2
4
3
34 18 2 4
9.00, H 3.64, N 4.60; found C 68.85, H 3.62, N 4.64.
(582.06): calcd. C 70.16, H 3.12, N 4.81; found C 69.72, H 3.15, N
.99.
4
[Pd(anthraphen)] (9): A solution of [Pd(OAc) ] (55 mg, 0.25 mmol)
2
in methanol (5 mL) was added to a suspension of H (anthraphen)
[Zn(anthraphen)] (12):
A solution of [Zn(hmds)2] (77 mg,
2
(1; 108 mg, 0.208 mmol) in tetrahydrofuran (20 mL) and the result- 0.20 mmol) in toluene (5 mL) was added to a suspension of H2-
ing mixture was heated at reflux for 3 h. The reaction mixture was
filtered at +4 °C, washed with cold tetrahydrofuran, and dried in
vacuo. [Pd(anthraphen)] (9; 121 mg, 93 %) was obtained as a green-
(anthraphen) (1; 100 mg, 0.192 mmol) in toluene (15 mL) and the
resulting suspension was heated at reflux for 1.5 h. The reaction
mixture was filtered at +4 °C, washed with cold toluene, and dried
in vacuo. [Zn(anthraphen)] (12; 70 mg, 62 %) was obtained as a
1
black solid. H NMR (CDCl , TMS, 300 MHz; pt: pseudo triplet): δ =
3
3
3
1
8
8
.32 (d, J = 7.8 Hz, 2 H, 5-H, 15-H), 7.96 (d, J = 7.9 Hz, 2 H,
dark-red solid. H NMR (CDCl +C D N, TMS, 300 MHz; pt: pseudo
H,H
H,H
3
5 5
3
4
3
4
-H, 18-H), 7.84 (dd, J = 7.0, J = 0.9 Hz, 2 H, 4-H, 14-H), 7.72
triplet): δ = 8.24 (dd, J = 7.7, J = 0.8 Hz, 2 H, 5-H, 15-H), 7.65
H,H
H,H
H,H H,H
3
3
4
3
3
(
pt, J = 7.3 Hz, 2 H, 6-H, 16-H), 7.65 (dd, JH,H = 7.5, J = 0.9 Hz, (d, J = 7.6 Hz, 2 H, 8-H, 18-H), 7.58 (pt, J = 7.5 Hz, 2 H, 6-H,
H,H H,H H,H H,H
3
4
2
H, 2-H, 12-H), 7.59–7.53 (m, 4 H, 7-H, 17-H, 3-H, 13-H), 6.84 (dd, 16-H), 7.49 (dd, J = 5.9, J = 2.6 Hz, 2 H, 4-H, 14-H), 7.44 (dpt,
H,H H,H
3
3
3
4
JH,H = 6.3, 3.4 Hz, 2 H, 24-H, 25-H), 6.69 (dd, J = 6.3, 3.4 Hz, 2
H, 23-H, 26-H) ppm. C NMR (CDCl , TMS, 125 MHz): δ = 183.7 (C-
JH,H = 7.88, J = 1.2 Hz, 2 H, 7-H, 17-H), 7.38–7.31 (m, 4 H, 2-H,
H,H
H,H
13
3
4
12-H, 3-H, 13-H), 6.76 (dd, J = 6.1, J = 3.4 Hz, 2 H, 24-H, 25-
H,H H,H
H), 6.52 (dd, J
3
3
4
13
1
1
0, C-20), 166.6 (C-1, C-11), 160.7 (C-9, C-19), 147.7 (C-21, C-22),
34.1 (C-5a, C-15a), 134.0 (C-3, C-13), 132.8 (C-6, C-16), 132.7, 132.6
= 6.1, J
= 3.4 Hz, 2 H, 23-H, 26-H) ppm.
C
H,H
H,H
NMR (CDCl +C D N, TMS, 75 MHz): δ = 185.2 (C-10, C-20), 170.5 (C-
3
5 5
(C-4a, C-14a, C-8a, C-18a), 132.1 (C-7, C-17), 131.2 (C-8, C-18), 130.3
1, C-11), 165.9 (C-9, C-19), 141.7 (C-21, C-22), 134.7 (C-5a, C-15a),
(C-2, C-12), 128.2 (C-5, C-15), 125.9 (C-23, C-26), 125.5 (C-24, C-25), 133.3 (C-4a, C-14a), 133.2 (C-3, C-13), 132.6 (C-8a, C-18a), 131.7 (C-
1
22.5 (C-1a, C-11a), 119.3 (C-4, C-4) ppm. IR: ν = 1650 (m), 1578 (m),
2, C-12), 131.5 (C-6, C-16), 131.2 (C-7, C-17), 129.3 (C-8, C-18), 127.7
˜
Eur. J. Inorg. Chem. 2016, 477–489
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487 © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

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(
1
1
C-5, C-15), 126.2 (C-24, C-25), 123.8 (C-23, C-26), 119.7 (C-1a, C-11a),
[32] W. Kaim, Inorg. Chem. 2011, 50, 9752–9765.
[
33] A. Vlcek Jr., Coord. Chem. Rev. 2002, 230, 225–242.
15.4 (C-4, C-14) ppm. IR: ν˜ = 1662 (s), 1581 (s), 1558 (m), 1521 (s),
[
34] M. M. Khusniyarov, K. Harms, O. Burghaus, J. Sundermeyer, B. Sarkar, W.
474 (w), 1446 (w), 1417 (m), 1356 (w), 1343 (m), 1322 (m), 1296
Kaim, J. van Slageren, C. Duboc, J. Fiedler, Dalton Trans. 2008, 1355–
(
(
s), 1258 (s), 1243 (m), 1220 (m), 1188 (w), 1164 (m), 1142 (m), 1111
w), 1071 (w), 1043 (w), 1020 (w), 887 (m), 830 (w), 792 (m), 776 (m),
1
365.
[
[
[
35] O. Siri, P. Braunstein, Chem. Commun. 2000, 2223–2224.
36] Q.-Z. Yang, O. Siri, P. Braunstein, Chem. Commun. 2005, 2660–2662.
37] B. Sarkar, S. Schweinfurth, N. Deibel, F. Weisser, Coord. Chem. Rev. 2015,
7
5
(
51 (s), 731 (w), 709 (s), 692 (w), 674 (w), 663 (m), 601 (w), 561 (w),
–
1
40 (m), 518 (w), 499 (w), 463 (w) cm . MS (APCI–, CH Cl ): m/z
2
2
–
%) = 617.31 (30). HRMS: calcd. for [M + Cl] 617.0252; found
2
93, 250–262.
6
17.0249. C H N O Zn (583.90): calcd. C 69.94, H 3.11, N 4.80;
34
18
2
4
[38] C. G. Pierpont, C. W. Lange, Prog. Inorg. Chem. 1994, 41, 381–492.
[39] H. Chun, T. Weyhermüller, E. Bill, K. Wieghardt, Angew. Chem. Int. Ed.
found C 69.86, H 3.25, N 4.76.
2
001, 40, 2489–2492; Angew. Chem. 2001, 113, 2552.
40] A. A. Kutyrev, S. J. Fomin, V. V. Moskva, Russ. J. Gen. Chem. 1996, 66, 776–
83.
[
Acknowledgments
7
[41] T. V. Kharlamova, Chem. Nat. Compd. 2009, 45, 629–633.
[42] S. I. Popov, V. P. Volosenko, Russ. J. Org. Chem. 1982, 18, 145–149.
[43] T. Tsuchiya, S. Ohmuro, Tetrahedron Lett. 2002, 43, 611–615.
This work was supported by the Deutsche Forschungsgemein-
schaft (DFG) within the graduate school “Functionalization of
Semiconductors” (GRK 1782).
[44] V. P. Volosenko, S. I. Popov, Russ. J. Org. Chem. 1981, 17, 874–875.
[
[
[
45] A. A. Kutyrev, S. J. Fomin, V. V. Moskva, Russ. J. Gen. Chem. 1996, 66, 757–
64.
46] N. B. Pahor, M. Calligaris, G. Nardin, L. Randaccio, Acta Crystallogr., Sect.
B 1978, 34, 1360–1363.
47] V. Z. Mota, G. S. G. de Carvalho, P. P. Corbi, F. R. G. Bergamini, A. L. B.
Formiga, R. Diniz, M. C. R. Freitas, A. D. da Silva, A. Cuin, Spectrochim.
Acta Part A 2012, 99, 110–115.
7
Keywords: N,O ligands · Schiff bases · Transition metals ·
Ligand design · Chromophores
[
[
[
[
1] H. Schiff, Ann. Chem. Pharm. 1864, 131, 118–119.
2] P. A. Vigato, S. Tamburini, Coord. Chem. Rev. 2004, 248, 1717–2128.
3] F. Bedioui, Coord. Chem. Rev. 1995, 144, 39–68.
4] R. Drozdzak, B. Allaert, N. Ledoux, I. Dragutan, V. Dragutan, F. Verpoort,
Coord. Chem. Rev. 2005, 249, 3055–3074.
[48] P. E. Riley, V. L. Pecoraro, C. J. Carrano, J. A. Bonadies, K. N. Raymond,
Inorg. Chem. 1986, 25, 154–160.
[49] M. Gerloch, F. E. Mabbs, J. Chem. Soc. A 1967, 1900–1908.
[50] S. Brückner, M. Calligaris, G. Nardin, L. Randaccio, Acta Crystallogr., Sect.
B 1969, 25, 1671–1674.
[51] M. A. Siegler, M. Lutz, Cryst. Growth Des. 2009, 9, 1194–1200.
[52] N. Kumari, R. Prajapati, L. Mishra, Polyhedron 2008, 27, 241–248.
[53] W. Sawodny, U. Thewalt, E. Potthoff, Acta Crystallogr., Sect. C 1999, 55,
2060–2061.
[
[
[
5] C. Ettling, Ann. Chem. Pharm. 1840, 35, 241–276.
6] M. D. Hobday, T. D. Smith, Coord. Chem. Rev. 1972, 9, 311–337.
7] P. Pfeiffer, E. Breith, E. Lübbe, T. Tsumaki, Justus Liebigs Ann. Chem. 1933,
5
03, 84–130.
[
[
8] P. G. Cozzi, Chem. Soc. Rev. 2004, 33, 410–421.
9] T. Katsuki, J. Mol. Catal. A 1996, 113, 87–107.
[54] M. M. Bhadbhade, D. Srinivas, Inorg. Chem. 1993, 32, 6122–6130.
[
[
[
10] E. M. McGarrigle, D. G. Gilheany, Chem. Rev. 2005, 105, 1563–1602.
11] E. N. Jacobsen, Acc. Chem. Res. 2000, 33, 421–431.
12] M. Tokunaga, J. F. Larrow, F. Kakiuchi, E. N. Jacobsen, Science 1997, 277,
[55] M. Odoko, N. Tsuchida, N. Okabe, Acta Crystallogr., Sect. E 2006, 62, 708–
09.
[56] A. F. Holleman, E. Wiberg, N. Wiberg, Lehrbuch der Anorganischen Chemie,
01st ed., de Gruyter, Berlin, 1995.
[57] R. H. Thomson, Naturally Occuring Quinones, Academic Press, London,
971.
[58] P. E. Aranha, M. P. dos Santos, S. Romera, E. R. Dockal, Polyhedron 2007,
6, 1373–1382.
7
936–938.
1
[
[
13] D. J. Darensbourg, Chem. Rev. 2007, 107, 2388–2410.
14] A. Decortes, A. M. Castilla, A. W. Kleij, Angew. Chem. Int. Ed. 2010, 49,
1
9822–9837; Angew. Chem. 2010, 122, 10016.
[
[
15] Y. Shimazaki, D. P. Stack, T. Storr, Inorg. Chem. 2009, 48, 8383–8392.
16] O. Rotthaus, O. Jarjayes, C. Philouze, C. P. D. Valle, F. Thomas, Dalton Trans.
2
[
[
[
59] B. Bosnich, J. Am. Chem. Soc. 1968, 90, 62.
2
009, 1792–1800.
17] T. Storr, P. Verma, Y. Shimazaki, E. C. Wasinger, T. D. P. Stack, Chem. Eur. J.
010, 16, 8980–8983.
18] T. Storr, P. Verma, R. C. Pratt, E. C. Wasinger, Y. Shimazaki, T. D. P. Stack, J.
Am. Chem. Soc. 2008, 130, 15448–15459.
60] B. Ortiz, S.-M. Park, Bull. Korean Chem. Soc. 2000, 21, 405–411.
61] O. Rotthaus, F. Thomas, O. Jarjayes, C. Philouze, E. Saint-Aman, J.-L. Pierre,
Chem. Eur. J. 2006, 12, 6953–6962.
[
[
[
[
[
[
[
[
2
[
[
62] P. Siega, V. Vrdoljak, C. Tavagnacco, R. Dreos, Inorg. Chim. Acta 2012, 387,
9
3–99.
19] T. Storr, E. C. Wasinger, R. C. Pratt, T. D. P. Stack, Angew. Chem. Int. Ed.
63] A. Kochem, H. Kanso, B. Baptiste, H. Arora, C. Philouze, O. Jarjayes, H.
2007, 46, 5198–5201; Angew. Chem. 2007, 119, 5290.
Vezin, D. Luneau, M. Orio, F. Thomas, Inorg. Chem. 2012, 51, 10557–
20] O. Rotthaus, O. Jarjayes, F. Thomas, C. Philouze, C. P. D. Valle, E. Saint-
Aman, J.-L. Pierre, Chem. Eur. J. 2006, 12, 2293–2302.
21] Y. Shimazaki, F. Tani, K. Fukui, Y. Naruta, O. Yamauchi, J. Am. Chem. Soc.
1
0571.
[
[
64] T. Kurahashi, H. Fujii, Inorg. Chem. 2013, 52, 3908–3919.
65] W. L. F. Armarego, D. D. Perrin, Purification of Laboratory Chemicals, 4th
ed., Elsevier, Burlington, 1996.
2003, 125, 10512–10513.
22] M. M. Khusniyarov, E. Bill, T. Weyhermüller, E. Bothe, K. Harms, J. Sunder-
meyer, L. Wieghardt, Chem. Eur. J. 2008, 14, 7608–7622.
23] a) B. A. Jazdzewski, W. B. Tolman, Coord. Chem. Rev. 2000, 200–202, 633–
[
66] M. M. Olmstead, P. P. Power, S. C. Shoner, Inorg. Chem. 1991, 30, 2547–
2
551.
[
[
[
67] H. Bürger, U. Wannagat, Monatsh. Chem. 1963, 94, 1007–1012.
68] J. Chatt, M. L. Searle, Inorg. Synth. 1957, 5, 210–215.
69] H. Bürger, W. Sawodny, U. Wannagat, J. Organomet. Chem. 1965, 3, 113–
685; b) G. H. Loew, D. L. Harris, Chem. Rev. 2000, 100, 407–419.
24] a) V. Lyaskovskyy, B. de Bruin, ACS Catal. 2012, 2, 270–279; b) O. R. Luca,
R. H. Crabtree, Chem. Soc. Rev. 2013, 42, 1440–1459.
1
20.
[
[
25] C. G. Pierpont, Coord. Chem. Rev. 2001, 216–217, 99–125.
26] P. Verma, J. Weir, L. Mirica, T. D. P. Stack, Inorg. Chem. 2011, 50, 9816–
[70] G. R. Fulmer, A. J. M. Miller, N. H. Sherden, H. E. Gottlieb, A. Nudelman,
B. M. Stoltz, J. E. Bercaw, K. I. Goldberg, Organometallics 2010, 29, 2179–
2179.
[71] APEX2, Bruker AXS Inc., Madison, WI, 2007; SAINT, Bruker AXS Inc., Mad-
ison, WI, 2007.
[72] X-AREA, Stoe & Cie, Darmstadt, Germany, 2002; X-RED, Stoe & Cie, Darm-
stadt, Germany, 2002.
[73] L. J. Farrugia, J. Appl. Crystallogr. 2012, 45, 849–854.
9
825.
27] K. Ray, T. Petrenko, K. Wieghardt, F. Neese, Dalton Trans. 2007, 1552–
566.
[
1
[
[
[
[
28] D. Schweinfurth, F. Weisser, B. Sarkar, Nachr. Chem. 2009, 57, 862–866.
29] W. Kaim, Coord. Chem. Rev. 2011, 255, 2503–2513.
30] W. Kaim, B. Schwederski, Coord. Chem. Rev. 2010, 254, 1580–1588.
31] W. Kaim, Eur. J. Inorg. Chem. 2012, 343–348.
Eur. J. Inorg. Chem. 2016, 477–489
www.eurjic.org
488
© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Full Paper
[
74] A. Altomare, M. C. Burla, M. Camalli, G. L. Cascarano, C. Giacovazzo, A.
[77] R. H. Blessing, Acta Crystallogr., Sect. A 1995, 51, 33–38.
Guagliardi, A. G. G. Moliterni, G. Polidori, R. Spagna, J. Appl. Crystallogr.
[78] SADABS, v. 2012/1, Bruker AXS Inc., Madison, WI, 2012.
1999, 32, 115–119.
[79] K. Brandenburg, DIAMOND, Crystal Impact GbR, Bonn, Germany, 1999.
[
[
75] G. M. Sheldrick, Acta Crystallogr., Sect. A 2008, 64, 112–122.
76] A. L. Spek, Acta Crystallogr., Sect. D 2009, 65, 148–155.
Received: November 20, 2015
Published Online: January 5, 2016
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489
© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim