Hybrid α-Diimine/Bis(chalcogenoether) Ligands for Copper(I) and Copper(II) Complexes

Article abstract of DOI:10.1002/zaac.201800073

The new ligands L = 1,4-bis(2-methylchalcogenophenyl)-2,3-dimethyl-1,4-diaza-1,3-diene [chalcogen = O (1), S (2) or Se (3)] have been studied in their coordination behavior towards Cu^I and Cu^II. Whereas the O-ether containing ligand forms complex ions [Cu(L)₂]ⁿ⁺ = 4ⁿ⁺, with exclusive N-coordination (n = 1) or N and weaker O coordination (n = 2), the species with E = S or Se contain tetradentate ligands in [Cu(L)]⁺ (5⁺, 6⁺) and [Cu(L)L′]ⁿ⁺ [n = 1, L′ = TfO^– (E = S) or n = 2 and L′ = H₂O (E = Se)]. Molecular structures in the crystals of 5⁺ and 6⁺ show distorted tetrahedral N coordination at the metal and innocently behaving α-diimine functions, in agreement with spectroscopic and computational data. The copper(II) ions [Cu(L)L′]²⁺ with one tetradentate ligand L = 2 or 3 exhibit a square-pyramidal configuration at the metal. Two isolated crystalline forms of 4²⁺ show weak coordination (2.636–2.96 ?) of three or four ether oxygen atoms, resulting in 4+3 or 4+4 coordination arrangements for N and O donors, respectively. In agreement with the rather different Cu^I and Cu^II structures the electrochemical oxidation of the copper(I) complexes and the reduction of the corresponding Cu^II species reveal an ECEC behavior within a square scheme, whereas the reduction of the Cu^I compounds, most likely at the diimine site, proceeds irreversibly. UV/Vis spectroelectrochemical results showing intense MLCT and IL absorptions were analyzed with the help of TD-DFT calculations.

Full text of DOI:10.1002/zaac.201800073

Journal of Inorganic and General Chemistry
DOI: 10.1002/zaac.201800073
ARTICLE
Zeitschrift für anorganische und allgemeine Chemie
Hybrid α-Diimine/Bis(chalcogenoether) Ligands for Copper(I) and
Copper(II) Complexes
Martina Bubrin,[a] Hana Kvapilová,[b] Jan Fiedler,[b] Fabian Ehret,[a] Stanislav Zálisˇ,[b] and Wolfgang Kaim*[a]
Dedicated to Professor Peter Comba on the Occasion of his 65th Birthday
[Cu(L)LЈ]2+ with one tetradentate ligand L = 2 or 3 exhibit a square-
Abstract. The new ligands L = 1,4-bis(2-methylchalcogenophenyl)-
pyramidal configuration at the metal. Two isolated crystalline forms
of 42+ show weak coordination (2.636–2.96 Å) of three or four ether
oxygen atoms, resulting in 4+3 or 4+4 coordination arrangements for
N and O donors, respectively. In agreement with the rather different
CuI and CuII structures the electrochemical oxidation of the copper(I)
complexes and the reduction of the corresponding CuII species reveal
an ECEC behavior within a square scheme, whereas the reduction of
the CuI compounds, most likely at the diimine site, proceeds irrevers-
ibly. UV/Vis spectroelectrochemical results showing intense MLCT
and IL absorptions were analyzed with the help of TD-DFT calcula-
2,3-dimethyl-1,4-diaza-1,3-diene [chalcogen = O (1), S (2) or Se (3)]
have been studied in their coordination behavior towards CuI and CuII.
Whereas the O-ether containing ligand forms complex ions
[Cu(L)2]n+ = 4n+, with exclusive N-coordination (n = 1) or N and
weaker O coordination (n = 2), the species with E = S or Se contain
tetradentate ligands in [Cu(L)]+ (5+, 6+) and [Cu(L)LЈ]n+ [n = 1, LЈ =
TfO– (E = S) or n = 2 and LЈ = H2O (E = Se)]. Molecular structures
in the crystals of 5+ and 6+ show distorted tetrahedral N coordination
at the metal and innocently behaving α-diimine functions, in agreement
with spectroscopic and computational data. The copper(II) ions tions.
sociated with metals in lower oxidation states.[8] On the other
Introduction
hand, α-diimines have been rarely used in such model li-
gands,[9] in contrast to numerous such salen ligands.[10,11]
Whereas the latter favor five- and six-membered chelate ring
formation, the ligands 1–3 allow only five-membered chelate
ring structures in complexes (Scheme 2).
Redox pairs containing the two neighboring oxidation states
CuI and CuII with their significantly different coordination
preferences[1] have received much attention because of the role
played by corresponding “blue” copper proteins in understand-
ing biological electron transfer.[2] Typical such centers in the
blue copper proteins[3] with “type 1” copper centers[1,4] have
a {Cu(His)2(Cys–)(Met)}n (n = 0 or +) coordination arrange-
ment.[4] Numerous model compounds of these composition
have been reported in attempts to mimic structural, spectro-
scopic and electrochemical properties of the blue copper pro-
teins.[5,6]
Scheme 1. The potentially tetradentate ligands in s-cis conformation.
In contrast to this N2S2 donor set in {Cu(His)2(Cys–)(Met)}n
with predominantly electron-rich ligands we have now chosen
a ligand type 1–3 with an N2E2 (E = O, S, Se) donor atom set
containing the π accepting α-diimine function as comple-
mented by two chalcogenoether donors E (Scheme 1). Al-
though chalcogenoethers have been reported as less π acidic[7]
they are distinguished in the biochemical context as being as-
* Prof. Dr. Wolfgang Kaim
Fax: +49 711 685 64165
E-Mail: kaim@iac.uni-stuttgart.de
[a] Institut für Anorganische Chemie
Universität Stuttgart
Pfaffenwaldring 55
70550 Stuttgart, Germany
[b] J. Heyrovský Institute of Physical Chemistry
The Czech Academy of Sciences
Dolejsˇkova 3
Scheme 2. Complex ions studied.
18223 Prague, Czech Republic
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/zaac.201800073 or from the au-
thor.
Coordination preferences, molecular structures of ligands
and copper complexes, electrochemical and UV/Vis spectro-
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electrochemical properties were determined. Starting from the ordination but adopts the familiar[15–20] bis(α-diimine)cop-
copper(I) level an oxidation can be expected to lead to CuII, per(I) structure with a chelate-distorted tetrahedral coordina-
whereas reduction can produce persistent copper(I) com- tion at the metal (Figure 1, Table 1 and Table S3, Supporting
plexes[12] of α-diimine radical ligands.[13]
Information). Compound 1 thus acts only as a bidentate chelate
An important area of research using copper complexes of ligand towards CuI due to the weakness of CuI–O bonds, espe-
α-diimines involves their photochemical activity[14] and their cially with uncharged central oxygen atoms. While such com-
suitability to act in topologically non-trivial molecules,[15,16] pounds have been shown to exhibit metal-to-ligand charge
culminating in the recognition, analysis[17] and the specific de- transfer in low-lying excited states,[14] the bond parameters of
velopment of molecular machines.[18]
4+ suggest only little π back donation[13] as indicated by
slightly lengthened C=N (1.30 Å) and shortened central C–C
bonds (1.484 Å), confirmed experimentally and computation-
ally (Table 1). The dihedral angle between the two N–Cu–N
chelate sections is 67.44°, right between the values found for
related [Cu(tBuN=C–C=NtBu)2](Br) at 89.5°)[19] and
[Cu(MesN=C–C=NMes)2](BF4) at 51.1°.[20a] Intramolecular
Results and Discussion
Synthesis and Structures
The Ligands
The new ligands 1,4-bis(2-methylchalcogenophenyl)-2,3-di-
methyl-1,4-diaza-1,3-diene (1–3) were obtained from 2,3-buta-
dione (diacetyl) with two equivalents of the corresponding an-
iline derivative. In addition to standard characterization of the
molecules (see Experimental Section) all three compounds 1–
3 were structurally characterized by X-ray diffraction (Figures
S1–S3, Tables S1 and S2, Supporting Information). Com-
pounds 2 and 3 were found to crystallize isostructurally with
two different half molecules in the unit cell. The molecular
structures are similar, with an s-trans conformation at the cen-
tral C–C bond (1.48–1.52 Å) and other typical bond lengths
such as about 1.28 Å for the C=N bonds of unreduced α-di-
imines (Table S2).
Complexes of the Ether Ligand 1
Reacting 1 with the copper(I) precursor [Cu(NCCH3)4](BF4)
in 1:1 or 2:1 ratio gave a complex with the composition
[Cu(1)2](BF4) = (4)(BF4) (Scheme 3). The crystal structure
Figure 1. Molecular structure of the cation in (4)(BF4); ellipsoids at
analysis revealed that this compound shows no chalcogen co- 50% level, hydrogen atoms and anion are omitted for clarity.
Scheme 3. Synthesis of copper complexes with ligand 1.
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a)
π–π interactions are observed (Figure 1) between phenyl rings Table 2. Selected bond lengths /Å and angles /° (experimental and
DFT calculated) of (4)(BF4)2.
at about 3.7 Å distance and a small dihedral angle of 3.5°.
b)
exp.
exp.c)
DFT calcd.
Table 1. Selected bond lengths /Å and angles /° (experimental and
DFT calculated) of (4)(BF4)].
P2/c
P212121
Bond length
Cu1–N1
Cu1–N2
Cu1–N3
Cu1–N4
Cu1–O4
Cu1–O1
Cu1–O3
Cu1–O2
N1–C2
N2–C3
N3–C31
N4–C32
C2–C3
Bond angle
N1–Cu1–N2
N1–Cu1–N3
N2–Cu1–N4
N3–Cu1–N4
N1–Cu1–N4
N2–Cu1–N3
O4–Cu1–O1
Bond length / Angle
exp.
DFT calcd.
1.982(11)
2.016(11)
2.002(9)
1.991(10)
2.727(10)
2.654(11)
2.869(9)
2.961(10)
1.245(16)
1.303(14)
1.282(14)
1.236(15)
1.498(17)
1.999(1)
1.986(1)
1.984(1)
2.006(1)
2.636(1)
2.655(1)
2.836(1)
4.332(1)
1.281(2)
1.296(2)
1.285(2)
1.285(2)
1.494(2)
2.009
2.009
2.009
2.009
2.805
2.804
2.805
2.804
1.289
1.289
1.289
1.289
1.495
Cu1–N1
Cu1–N2
N1–C2
N1–C11
N2–C3
N2–C21
C1–C2
C2-C3
1.977(2)
2.002(2)
1.297(4)
1.434(4)
1.297(4)
1.414(4)
1.502(4)
1.484(4)
1.502(4)
1.399(4)
1.395(4)
1.368(4)
1.424(4)
1.407(4)
1.390(4)
1.362(4)
1.432(4)
80.33(10)
116.56(15)
113.66(15)
1.987
1.996
1.295
1.402
1.294
1.402
1.495
1.483
1.491
1.393
1.411
1.349
1.414
1.411
1.393
1.351
1.413
80.4
C3–C4
C11–C16
C11–C12
O1–C16
O1–C161
C21–C26
C21–C22
O2–C26
O2–C261
N1–Cu1–N2
N1–Cu1–N1#a)
N2–Cu1–N2#a)
80.1(4)
101.3(5)
109.3(4)
80.4(4)
160.4(4)
146.8(4)
65.1(3)
80.38(6)
103.09(6)
106.01(5)
80.11(5)
143.80(5)
164.79(6)
80.8
104.9
105.0
80.9
154.2
154.2
64.4
113.2
114.0
a) Two different crystal forms available, cf. main text. b) See experi-
mental section for refinement restraints. c) From 1,2-dichloroethane
solvate.
Symmetry operation to generate equivalent atoms: #1 –x,y,–z + 1/2
#2 –1,y,–z + 1/2.
Using AgBF4 as oxidant, the reaction with 4+ in CH2Cl2
yields a compound with the composition [Cu(1)2](BF4)2 = (4)
(BF4)2 as confirmed by crystal structure analyses of two forms
(Table 2 and Table S3, Supporting Information), monoclinic
(P2/c, as a CH2Cl2 solvate with limited quality, Figure 2), and
orthorhombic (P212121, as a 1,2-dichloroethane solvate, Figure
S4, Supporting Information). The former contains both ligands
1 as tetradentate, resulting in the rare[21] coordination number
of eight for the metal. The higher quality structure obtained
for the orthorhombic system exhibits a coordination number of
seven for CuII, i.e. one uncoordinated ether oxygen atom in
one tridentate ligand 1.
Although the difference between copper(II) and copper(I)
cases may be conveniently traced to the higher charge of CuII,
the other factor, the preference for higher coordination num-
bers of copper(II) also plays a crucial role. While the ligand
shows otherwise conventional bond parameters (1.29 Å for
C=N, 1.49 Å for connecting C–C bond), the coordination at
the metal can be described as 4+4 or 4+3, considering the long
but still adequate Cu–O bonds of 2.636–2.96 Å. At 2.00 Å the
CuII–N and CuI–N bonds are similar, reflecting the absence of
significant back donation in both cases. Concerning the de-
scription of the coordination structure in the more symmetrical
monoclinic case, a distorted dodecahedron (Figure 2) with in-
terspersing N4 and O4 bisphenoids of different size can be
invoked.[22] The DFT calculations confirm the structure and
the 4+4 coordination pattern (Table 2). At about 40° the dihe-
dral angles between N–Cu–N planes are smaller than in the
CuI case (67.4°), reflecting the tendency for planarity. The di-
hedral angles between O–Cu–O sections are only 14°. Intramo-
lecular π–π interactions are again present (Figure 2) between
phenyl rings in both crystalline forms.
Figure 2. Molecular structure of one of two crystallographically inde-
pendent dications in the asymmetric unit of (4)(BF4)2 (top) in the mo-
noclinic crystal of the dichloromethane solvate; ellipsoids at 30%
level, hydrogen atoms and anions are omitted for clarity. Bottom: The
coordination sphere in polyhedral representation.
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The packing and weak hydrogen bonding may be responsi-
ble for the different coordination of 1 in the dichloromethane
vs. the 1,2-dichloroethane solvate (Figure 2 and Figure S4,
Supporting Information). It confirms the hemilabile[23] nature
of 1 with less basic neutral oxygen donor atoms.
Complexes of the Thioether and Selenoether Ligands 2 and 3
Reacting the ligands 2 or 3 with copper precursors yields
compounds 5n and 6n with tetradentate chelates (Scheme 4,
Scheme 5). As indicated in Scheme 4, the copper(I) form 5+
was observed from reacting copper(II) precursors with 2 in
ethanol, which suggests a redox process involving that poten-
tially reducing solvent.[24a] Electrochemical oxidation of eth-
anol has been observed at about 0.7 V vs. SCE[24b] which is
close to the typical CuII-to-CuI reduction in the presence of π
acceptor ligands (Table S6, Supporting Information). However,
a copper(II) reduction involving the ligand cannot be ruled out.
The structures of the copper(I) complex ions are similar
(Figure 3, Table 3, Table S4, Supporting Information). The di-
imine part remains unreduced (short C=N, long C–C bonds).
The CuI–E bonds are rather short, relative to CuII–E (Table 3),
reflecting some metal (π donor) to chalcogenoether (π ac-
ceptor) back donation. In compensation, the CuI–N bonds are
relatively long at about 2.06 Å.
The overall coordination is that of a severely distorted tetra-
hedron (Figure 4) with chelate-induced small angles down to
78° and large angles such as E–CuI–E (134° for E = S, 125°
for E = Se). The dihedral angles between respective N–Cu–N
and E–Cu–E planes are 43.2° in (5+)(BF4) and 40.8° in (6+)
(ClO4), far from the 90° expected for a regular tetrahedron.
Copper(II) precursors react with L = 2 or 3 in dichlorometh-
ane to yield complexes with five coordinate metal, the tetra-
dentate L being complemented by one O donor ligand.
While compound [5(OTf)](OTf) could be crystallized as
such for X ray diffraction, attempts to obtain a suitable crystal-
line compound containing of 62+ were eventually successful
Figure 3. Molecular structures of (5)(BF4) (top) and (6)(ClO4) (bot-
tom); ellipsoids at 50% level, hydrogen atoms and anions are omitted
for clarity.
when using Cu(OTf)2 in reagent grade (i.e. not dried) dichloro- [6(H2O)](OTf)2 could be obtained (Figure 5 and Figure S5,
methane for crystallization from which complex Table 3).
a
Scheme 4. Syntheses of copper complexes with ligand 2 (CuII Ǟ CuI reduction by solvent).
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Scheme 5. Syntheses of copper complexes with ligand 3.
Table 3. Selected bond lengths /Å and angles /° (experimental and DFT calculated ) for sulfur and selenium containing compounds
a)
b)
.
a)
a)
b)
b)
(5)(BF4)
[(5)(OTf)](OTf)
(6)(ClO4)
[(6)(H2O)](OTf)2
exp.
calcd.
exp.
calcd.
exp.
calcd.
exp.
calcd.
Bond length
Cu–N1
Cu–N2
Cu–E1
Cu–E2
Cu–O1
N1–C2
N2–C3
C2–C3
2.058(5)
2.068(5)
2.270(2)
2.235(2)
2.060
2.060
2.233
2.233
1.953(4)
1.970(4)
2.346(2)
2.288(2)
2.172(4)
1.290(6)
1.282(6)
1.504(7)
1.785(5)
1.813(5)
1.784(5)
1.815(5)
1.967
1.986
2.375
2.311
2.068
1.290
1.294
1.495
1.785
1.814
1.785
1.820
2.060(2)
2.074(2)
2.370(0)
2.372(0)
2.070
2.071
2.348
2.348
1.984(3)
1.984(3)
2.430(0)
2.433(0)
2.152(2)
1.287(4)
1.290(4)
1.504(5)
1.931(4)
1.956(4)
1.942(3)
1.964(4)
1.995
1.999
2.435
2.434
1.287(8)
1.305(8)
1.484(8)
1.783(6)
1.806(6)
1.767(6)
1.799(6)
1.288
1.288
1.483
1.768
1.801
1.768
1.801
1.290(3)
1.290(3)
1.495(3)
1.933(2)
1.959(2)
1.922(2)
1.952(3)
1.291
1.291
1.485
1.917
1.946
1.917
1.946
1.294
1.295
1.503
1.918
1.945
1.919
1.946
E1–C16
E1–C161
E2–C26
E2–C261
Bond angle
N1–Cu–N2
N2–Cu–E2
E2–Cu–E1
E1–Cu–N1
N1–Cu–E2
N2–Cu–E1
78.4(2)
83.7(2)
133.98(6)
82.4(2)
137.1(2)
136.1(2)
78.6
83.5
130.9
83.5
139.2
139.2
81.0(2)
85.9(1)
101.32(5)
84.1(1)
156.7(1)
156.1(1)
81.8
86.0
103.5
82.6
163.9
150.0
78.66(7)
85.48(5)
125.35(2)
85.95(5)
143.78(6)
139.20(6)
78.2
84.5
139.8
84.6
136.8
136.8
80.42(1)
85.73(8)
100.67(2)
85.06(8)
156.54(8)
155.48(8)
80.5
85.1
101.6
83.9
156.2
153.2
a) Calculations for cations or dications. b) E = S or Se.
bonds to the O ligands are not too long at 2.172(4) Å for
[5(OTf)]+ and only 2.152(2) Å for [6(H2O)]2+.
EPR Spectroscopy
The copper(II) forms exhibit conventional[2,17] EPR signals
(Figure S6, Supporting Information), and the parameters are
listed in Table 4. In contrast to 42+, the frozen solutions of 52+
and 62+ show the presence of two species. It is assumed that
exchange equilibria for the axial ligand from the external envi-
ronment (counterion, solvents) are responsible, which are dis-
tinguished from the binding of intraligand O donors for 42+.
Spin density calculations (Figure 6 and Figure S6, Supporting
Figure 4. Coordination polyhedra 5+ (left) and 6+ (right): Copper (tur-
quoise), nitrogen (blue), sulfur (yellow), and selenium (deep red).
As mentioned above the CuII–E bonds are relatively long Information) confirm 2/3 of spin on the metal in 42+, whereas
(e.g. 2.43 Å for [6(H2O)]2+ vs. 2.37 Å for 6+) whereas the 52+ and 62+ exhibit lower copper (ca. 55%) and increased
CuII–N bonds are shorter at 1.97 Å vs. 2.06 Å for CuI–N. The chalcogen spin density (ca. 25% for two S or Se).
coordination polyhedron is a typical square pyramid (Figure
Metal compounds of α-diimines frequently undergo revers-
S5, Supporting Information) with τ values[25] near 0. The axial ible reduction to radical complexes,[13] however, Hartl and co-
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Figure 6. DFT calculated spin densities of 52+ (left) and 62+ (right)
(DFT/PCM-CH2Cl2).
meric radical complexes could not be detected by EPR on re-
duction.
Electrochemistry
The electrochemistry of CuI/CuII couples is affected by their
rather different structures, which typically causes square
scheme behavior (see Scheme 6 and Scheme 7)[17,27] with cy-
clic voltammetry peaks shifted due to chemical reactions ac-
companying electron transfer. Such behavior has been ob-
served here too. Cyclic voltammetry of compounds (4)(BF4),
(4)(BF4)2, (5)(BF4), (5)(OTf)2, (6)(ClO4), and (6)(OTf)2 re-
vealed that the charge transfer processes proceed electrochemi-
cally less reversibly according to |Ep – Ep/2| Ͼ 60 mV.
Figure 5. Molecular structures of [5(OTf)]+ from [5(OTf)](OTf)·
CH2Cl2 (top) and of [6(H2O)]2+ from [6(H2O)](OTf)2 (bottom); non-
coordinated counterions, hydrogen atoms and solvent molecules are
omitted for clarity; 50% probability ellipsoids.
Table 4. Experimental and calculated results for EPR active species.a)
.
42+
52+ d)
62+ d)
g1
g2
g3
A1
A2
A3
ρCu
ρN
2.220
2.066
2.053
15.3
3.3
2.166
2.040
1.988
18.3
n.d.
2.236
2.057
1.986
13.1
n.d.
Scheme 6. Square scheme mechanism for the electron transfer of ether
complexes 4n+ with copper(I) and copper(II).
b)
b)
b)
Figure 7 and Figure 8 show representative cyclic voltammo-
grams in the potential range of CuI ↔ CuII transitions. Electro-
chemical simulations using DigiElch software (ElchSoft) indi-
cate rapid conversions following both charge transfers CuI to
CuII and CuII to CuI (Scheme 6 and Scheme 7, Tables S7 and
S8, Supporting Information). Diffusion coefficients required
for the simulation have been obtained from chronoamperome-
try and Cottrell plots.[28] Voltammetric scanning in a wider
0
n.d.
n.d.
c)
c)
c)
0.67
0.07
0.09
0.55
0.10
0.12
0.56
0.09
0.13
ρE
a) From spectra measured in CH2Cl2 at 110 K. b) Hyperfine constants
A in mT. c) TD-DFT/PCM-CH2Cl2 calculated spin densities. d) Main
component of equilibrium (see text).
workers have shown that dimerization can follow in some potential range revealed further irreversible reduction of all
cases.[26] A similar reactivity is assumed here because mono- compounds (5n+, 6n+, 7n+) at negative potentials; these pro-
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Scheme 7. Square scheme mechanism for the electron transfer of thio-
ether (5n+) and selenoether complexes (6n+) of copper.
cesses obviously belong to ligand-based electron uptake. The
experimental potentials are summarized in Table S6.
Figure 8. Cyclic voltammograms of 5+ (top) and 62+ (bottom) in 0.1 m
Bu4NOTf / CH2Cl2 at 100 mV·s–1 scan rate.
The experimental results are reasonably reproduced by the
computational data which allows for the following assignments
of major transitions: All compounds exhibit weak absorptions
(ε Ͻ 1100 m–1 cm–1) in the visible region, with maxima be-
tween 500 and 700 nm. The TD-DFT calculations suggest
transitions between fully (cations) or half occupied (dications)
orbitals of mixed metal/chalcogen character and the lowest un-
occupied MO based at the α-diimine acceptor site. An MLCT/
IL (metal-to-ligand charge transfer/intra-ligand) description
seems appropriate for these low-energy transitions with π*(α-
diimine) as the target orbital, in agreement with the results
from EPR spectroscopy and electrochemistry.
Figure 7. Cyclic voltammograms of 4+ in 0.1 m Bu4NPF6 / CH2Cl2 at
100 mV·s–1 scan rate and simulated cyclic voltammogram (parameters
in Table S7, Supporting Information).
The complexes have been also investigated by varying the
scan rate in order to reveal redox potentials (reversible half-
wave potentials) of the CuI/CuII couples in Scheme 6 and
Scheme 7. Employing high scan rate voltammetry, the coupled
chemical reactions can be at least partially avoided. However,
the limited rates of the charge transfer reactions (quasi-revers-
ibility of the charge transfer processes, see above) did not al-
low us to apply sufficiently high scan rates.
More intense absorptions are detected at higher energies.
The S and Se containing systems 5+/52+ and 6+/62+ have ab-
sorptions in the UV region around 360 nm, assigned to intra-
ligand transitions, whereas the oxygen complexes with their
1:2 metal ligand ratio absorb at longer wavelengths, still in the
visible around 500 nm, due to MLCT (4+) or IL transitions
(42+). Strong absorptions occur around 310 nm, which may be
identified as MLCT transitions to higher lying unoccupied
MOs.
UV/Vis/NIR Spectroelectrochemistry and TD-DFT
Calculations
The chemical reversibility of the CuI/II transition allowed us
to study both forms in their stable configurations using an op-
tically transparent thin-layer electrolysis (OTTLE) cell.[29]
The experimental results from Figure 9 and Table 5 are com-
plemented by TD-DFT calculations, which are summarized in
Tables S9–S11 (Supporting Information) Figures S7–S12
(Supporting Information) depict the molecular orbitals in-
volved.
The well studied CuI-diimine charge transfer processes[14,15]
occur in the near UV region below 360 nm for 5+ and 6+ and
do not contribute to the absorption in the visible.
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Typical square scheme behavior for CuI/CuII pairs with non-
entatic state[29] properties, i.e. different and effectively sepa-
rated coordination structures, was observed by cyclic voltam-
metry and analyzed through simulations, using kinetic and
thermodynamic parameters.
Analysis of the electronic structures by spectroscopy and
TD-DFT-supported (spectro)electrochemistry reveals the α-di-
imine acceptor location as the site of the LUMO in all com-
pounds. Yet the radicals formed on reduction proved to be too
reactive for detection, e.g., by EPR. The highest doubly (CuI)
or singly (CuII) occupied MO is made up from a metal-cen-
tered d orbital and, to a lesser extent, from chalcogen-based
orbitals. EPR parameters and absorption bands from MLCT/
IL transitions in the visible reflect this electronic structure.
While the reproduction of experimental results by DFT calcu-
lations has turned out to be successful for the example studied
herein, the application of other methods[30] is required for the
design of alternative ligands and for the prediction of struc-
tures and properties of copper complexes.
Experimental Section
Instrumentation: EPR spectra in the X band were recorded with a
Bruker System EMX. 1H-, 13C- and 77Se-NMR spectra were taken
with a Bruker AV 250 spectrometer. UV/Vis/NIR absorption spectra
were recorded with J&M TIDAS and Shimadzu UV 3101 PC spectro-
photometers. Cyclic voltammetry was carried out in 0.1 m electrolyte
solutions using a three-electrode configuration (glassy carbon working
electrode, Pt counter electrode, Ag/AgCl reference) and a PAR 273
potentiostat and function generator. The ferrocene/ferrocenium (Fc/
Fc+) couple served as internal reference. Spectroelectrochemistry was
performed with an optically transparent thin-layer electrode (OTTLE)
cell.[31]
Figure 9. UV/Vis spectroelectrochemical response for reduction of 52+
(CuII/CuI redox pair, top) and reduction of the CuI cation (bottom) in
0.1 m Bu4NOTf / CH2Cl2 at 295 K.
Synthesis of Ligand 1: 2,3-Butadione (10.5 mmol, 0.9 mL), o-anisi-
dine (21 mmol, 2.6 mL) and a catalytic amount of p-toluenesulfonic
acid were dissolved in 60 mL benzene. Heating to reflux for 3 h using
a water separator, removal of the solvent and crystallization from eth-
anol at –18 °C yielded 1 as a yellow solid (1.78 g, 6.0 mmol, 57%).
C18H20N2O2 (296.36 g·mol–1): calcd: C 72.95; H 6.80; N 9.45%;
found: C 72.97; H 6.85; N 9.46%. 1H NMR (250 MHz, C6D6): δ =
6.99–6.78 (m, 4 H), 6.71 (dd, J = 7.3, 2.1 Hz, 2 H), 6.60 (dd, J = 7.8,
1.5 Hz, 2 H), 3.24 (s, 6 H), 2.27 (s, 6 H). 13C NMR (63 MHz, C6D6):
δ = 169.42, 148.60, 140.91, 124.56, 121.04, 120.10, 111.72, 54.82,
15.76.
Table 5. UV/Vis absorption maxima for different charge states of com-
plex ions 5n and 6n from spectroelectrochemical measurements [λ /nm
(ε /m–1·cm–1)].
42+
4+
324 (3720)
349 (3480)
424 (4090)
543 (3150)
510sh
361 (10440)
350 (6010)
356 (3040)
364 (11990)
355 (6190)
530sh
650sh
52+
5+
5
319 (9160)
306 (14790)
274 (8610)
320 (9310)
307 (11750)
680 (870)
513 (1090)
62+
6+
617 (660)
521 (980)
Synthesis of Ligand 2: 2,3-Butadione (3.5 mmol, 0.3 mL) and 2-
methylthioaniline (7.2 mmol, 0.9 mL) were reacted in a similar pro-
cedure as for 1 to yield 344 mg (1.1 mmol, 30%) of a yellow solid.
C18H20N2S2 (328.48 g·mol–1): calcd: C 65.81; H 6.14; N 8.53%;
found: C 65.52; H 6.32; N 8.17%. 1H NMR (250 MHz, C6D6): δ =
7.09–7.02 (m, 2 H), 7.00–6.87 (m, 4 H), 6.54–6.47 (m, 2 H), 2.30 (s,
6 H), 1.97 (s, 6 H). 13C NMR (63 MHz, C6D6): δ = 169.07 (s), 148.81
(s), 128.93 (s), 125.86 (s), 125.22 (s), 124.44 (s), 117.94 (s), 15.60 (s),
14.42 (s).
Conclusions
This article describes copper(I) and coper(II) complexes of
new open-chain tetradentate ligands with two central π acidic
α-diimine N donor atoms and two chalcogenoether functions
(O, S, Se as chalcogens). While the S and Se containing com-
pounds are very similar, forming 1:1 complexes with largely
conventional coordination structures for CuI and CuII systems,
the O-ether analogues react to form complexes in 1:2 metal:-
ligand ratio. Ether-oxygen donors are uncoordinated in the CuI
complex ion, and unusual structures described as 4+4 and 4+3
coordination arrangements for N and O donors have been ob-
served for the copper(II) case.
Synthesis of Ligand 3: 2,3-Butadione (2.3 mmol, 0.2 mL) and 2-
methylselenoaniline[32] (4.8 mmol, 0.9 mL) were reacted in a similar
procedure as for 1 to yield 477 mg (1.1 mmol, 49%) of a yellow solid.
C18H20N2Se2 (422.28 g·mol–1): calcd. C 51.20; H 4.77; N 6.63%;
found: C 51.44; H 4.85; N 6.50%.1H NMR (250 MHz, CD2Cl2): δ =
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7.39 (dd, J = 7.7, 1.4 Hz, 1 H), 7.25 (td, J = 7.5, 1.5 Hz, 1 H), 7.14
isostructurally (Table S2). Crystals of compound (4)(BF4) and from
(td, J = 7.5, 1.5 Hz, 1 H), 6.74 (dd, J = 7.6, 1.5 Hz, 1 H), 2.36–2.27
(m, 3 H), 2.23 (d, J = 2.0 Hz, 3 H). 77Se NMR (76 MHz, CD2Cl2):
δ = 160.42 (s).
the complexes with the sulfur and selenium ligands (Tables S4 and S5)
were obtained from dichloromethane solutions at –18 °C. The tetra-
fluoroborate anion showed disorder along the F1-B1 axis. Crystalli-
zation of (4)(BF4)2 was accomplished by diffusion of ethyl ether into
a dichloromethane or 1,2-dichloroethane solution. Two different struc-
tures were thus obtained for this system: The crystals from CH2Cl2
(P2/c) showed poor quality with two independent molecules and one
solvent molecule in the asymmetric unit. ISOR restraints and Squeeze
procedures had to be used.[33] The crystal quality from dichloroethane
solution was better (P212121) even though a solvent molecule was also
present. Measurements were performed with an Apex II duo dif-
fractometer (Bruker). The crystals were kept at 100 or 110 K during
data collection. The structures were solved via direct methods (ligands)
or the Patterson procedure (complexes) with the SHELXL-97 structure
solution program[34] using Least Squares minimization. Non-hydrogen
atoms were refined anisotropically, hydrogen atoms were introduced
as per the riding model.
Synthesis of Complex (4)(BF4) = [Cu(1)2](BF4): [Cu(MeCN)4](BF4)
(0.12 mmol, 33.8 mg) was reacted with 1 (0.25 mmol, 74 mg) in
CH2Cl2 (20 mL) for 1 h at room temperature in an argon atmosphere.
Removal of the solvent, washing with toluene and drying under vac-
uum yielded 64 mg (0.08 mmol, 73%) of the purple compound (4)
(BF4). C36H40BCuF4N4O4 (743.07 g·mol–1): calcd: C 58.54; H 5.84;
N 7.38%; found: C 58.74; H 5.67; N 7.26%. 1H NMR (250 MHz,
CD2Cl2): δ = 7.35–7.17 (m, 1 H), 7.05–6.88 (m, 1 H), 6.69 (dd, J =
7.7, 1.6 Hz, 1 H), 3.69 (s, 2 H), 1.96 (s, 2 H).
Synthesis of Complex (4)(BF4)2 = [Cu(1)2](BF4)2: [Cu(MeCN)4]BF4
(0.25 mmol, 71 mg) was reacted with 1 (0.5 mmol, 148 mg) in CH2Cl2
for 1 h at room temperature in an argon atmosphere. Addition of
AgBF4 (1 equiv., 0.25 mmol, 48.5 mg), stirring for 1 h, filtration
through celite, and recrystallization from CH2Cl2/Et2O (3/1) yielded
Crystallographic data (excluding structure factors) for the structures in
this paper have been deposited with the Cambridge Crystallographic
Data Centre, CCDC, 12 Union Road, Cambridge CB21EZ, UK. Copies
of the data can be obtained free of charge on quoting the depository
numbers CCDC-1825427, CCDC-1825428, CCDC-1825429, CCDC-
1825430, CCDC-1825431, CCDC-1825432, CCDC-1825433, CCDC-
1825434, CCDC-1825435, and CCDC-1825436. (Fax: +44-1223-336-
033; E-Mail: deposit@ccdc.cam.ac.uk, http://www.ccdc.cam.ac.uk).
(4)(BF4)2 as
a
brown solid (128 mg, 0.16 mmol, 62%).
C36H40B2CuF8N4O4 (829.88 g·mol–1): calcd: C 49.14; H 4.77; N
6.03%; found: C 49.14; H 4.87; N 6.36%.
Synthesis of Complex (5)(BF4)
= [Cu(2)](BF4): Ligand 2
(0.10 mmol, 33 mg) and Cu(BF4)2 (0.1 mmol, 24 mg) were heated to
reflux for 5 h in ethanol (20 mL). After cooling the red precipitate was
collected by filtration and recrystallized from dichloromethane. The
purple solid (5)(BF4) was obtained in 66% yield (32 mg, 0.07 mmol).
C18H20BCuF4N2S2 (478.83 g·mol–1): calcd. C 45.15; H 4.21%; N
5.85%; found: C 45.28; H 4.21; N 5.58%. 1H NMR (250 MHz,
CD2Cl2): δ = 7.74 (dd, J = 8.0, 1.3 Hz, 2 H), 7.62–7.47 (m, 4 H), 2.87
(s, 6 H), 2.60 (s, 6 H).
DFT Calculations: The electronic structures of the complex ions were
calculated by density functional theory (DFT) methods using the
Gaussian 09.C01[35] program package. Open shell systems were calcu-
lated by the unrestricted Kohn-Sham approach (UKS). Geometry opti-
mization followed by vibrational analysis was made either in vacuo or
in solvent media. Electronic transitions were calculated by the time-
dependent DFT (TD-DFT) method.
Synthesis of Complex (5)(OTf)2 = [Cu(2)(OTf)](OTf): Cu(OTf)2
(9 mg, 0.16 mmol) and 3 (52 mg, 0.16 mmol) were reacted for 2 h at
room temperature in dry CH2Cl2 (40 mL). After 1 d of keeping this
mixture at –18 °C the precipitate formed was collected by filtration.
Washing with CH2Cl2 and toluene and drying yielded (5)(OTf)2 as a
green solid (89 mg, 0.13 mmol, 80%). C20H20CuF6N2O6S4
(690.18 g·mol–1): calcd. C 34.80; H 2.92; N 4.06%; found: C 34.65;
H 2.84; N 3.93%.
G09 calculations employed the Perdew, Burke, Ernzerhof[36,37] PBE0
hybrid functional (G09/PBE0). Polarized triple-ζ basis sets 6-
311G(3df) were used for all atoms.[38,39] Solvent effects were de-
scribed by the polarizable continuum model (PCM).[40]
Supporting Information (see footnote on the first page of this article):
Crystallographic data, Figures and parameters.
Synthesis of Complex (6)(ClO4) = [Cu(3)](ClO4): [Cu(MeCN)4]ClO4
(0.12 mmol, 39 mg) was reacted with 3 (0.12 mmol, 50 mg) in CH2Cl2
(10 mL) for 1 h at room temperature in an argon atmosphere. (Cau-
tion! Perchlorate salts are explosive and should be handled with care).
The purple solution was reduced to 5 mL and treated with Et2O for
precipitation. Recrystallization of the product from CH2Cl2/Et2O (3/1)
at –18 °C yielded (6)ClO4 as a purple solid (57 mg, 0.10 mmol, 81%).
C18H20ClCuN2O4Se2 (585.27 g·mol–1): calcd. C 36.94; H 3.44; N
4.79%; found: C 37.61; H 3.63; N 4.63%. 1H NMR (250 MHz,
CD2Cl2): δ = 7.72 (d, J = 7.7 Hz, 1 H), 7.53 (t, J = 7.3 Hz, 1 H), 7.41
(d, J = 7.7 Hz, 1 H), 7.34 (t, J = 7.8 Hz, 1 H), 2.59–2.39 (m, 1 H).
Acknowledgements
We thank Dr. Wolfgang Frey for crystallographic measurements. This
project was supported by the Land Baden-Württemberg. S.Z. thanks
the Ministry of Education of the Czech Republic (grant number
LTC17052) for support. J.F. thanks the Czech Science Foundation
(project 18–09848S) for support.
Keywords: Chalcogenoether ligands; Copper; α-Diimines;
Electrochemistry; Molecular structures
Synthesis of Complex (6)(OTf)2 = [Cu(3)(OTf)](OTf): Cu(OTf)2
(0.13 mmol, 50 mg) and 3 (0.13 mmol, 58 mg) were reacted at room
temperature for 2 h in dry CH2Cl2. Precipitation of the product after
keeping the mixture at –18 °C for 24 h, filtration and washings with
dichloromethane and toluene yielded (6)(OTf)2 as a green solid
(67 mg, 0.08 mmol, 65%). C20H20CuF6N2O6S2Se2 (783.96 g·mol–1):
calcd. C 30.64; H 2.57; N 3.57%; found: C 30.59; H 2.64; N 3.37%.
References
[1] W. Kaim, J. Rall, Angew. Chem. 1996, 108, 47–64; Angew. Chem.
Int. Ed. Engl. 1996, 35, 43–60.
[2] E. I. Solomon, R. G. Hadt, Coord. Chem. Rev. 2011, 255, 774–
789.
Crystallography: Suitable single crystals of ligands 1–3 were ob-
tained from ethanol solutions at –18 °C. Compounds 2 and 3 crystallize
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ARTICLE
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[3] E. I. Solomon, R. K. Szilagyi, S. DeBeer George, L. Basumallick,
680–699; c) A. Bader, E. Lindner, Coord. Chem. Rev. 1991, 108,
27–110.
Chem. Rev. 2004, 104, 419–458.
[24] a) I. E. Markó, P. R. Giles, M. Tsukazaki, S. M. Brown, C. J.
Urch, Science 1996, 274, 2044–2046; b) E. Sokolova, Electro-
chim. Acta 1975, 20, 323–330.
[25] A. W. Addison, T. N. Rao, J. Reedijk, J. van Rijn, G. C. Ver-
schoor, J. Chem. Soc., Dalton Trans. 1984, 1349–1356.
[26] B. D. Rossenaar, F. Hartl, D. J. Stufkens, C. Amatore, E. Maison-
haute, J.-N. Verpeaux, Organometallics 1997, 16, 4675–4685.
[27] M. M. Bernardo, P. V. Robandt, R. R. Schroeder, D. B. Rorab-
acher, J. Am. Chem. Soc. 1989, 111, 1224–1231.
[28] M. Bubrin, Ph. D. Thesis, Universität Stuttgart, Germany 2014.
[29] B. Dicke, A. Hoffmann, J. Stanek, M. S. Rampp, B. Grimm-Leb-
sanft, F. Biebl, D. Rukser, B. Maerz, D. Göries, M. Naumova, M.
Biednov, G. Neuber, A. Wetzel, S. M. Hofmann, P. Roedig, A.
Meents, J. Bielecki, J. Andreasson, K. R, Beyerlein, H. N. Chap-
man, C. Bressler, W. Zinth, M. Rübhausen, S. Herres-Pawlis, Nat.
Chem. 2018, 10, 355–362.
[30] a) P. Comba, T. W. Hambley, B. Martin, Molecular Modeling of
Inorganic Compounds, Wiley-VCH, Weinheim, Germany, 2009;
b) P. Comba, ed., Modeling of Molecular Properties, Wiley-VCH,
Weinheim, Germany, 2011.
[4] W. Kaim, B. Schwederski, A. Klein, Bioinorganic Chemistry, 2.
ed., Wiley, Chichester, 2013.
[5] J. Reedijk, J. Inorg. Biochem. 2012, 115, 182–185.
[6] K. D. Trotter, J. Reglinski, K. Robertson, J. C. Forgie, J. A. Park-
inson, A. R. Kennedy, D. R. Armstrong, R. J. Sowden, C. M.
Spickett, Inorg. Chim. Acta 2009, 362, 4065–4072.
[7] H.-B. Kraatz, H. Jacobsen, T. Ziegler, P. M. Boorman, Organome-
tallics 1993, 12, 76–80.
[8] Y. Xue, A. V. Davis, G. Balakrishnan, J. P. Stasser, B. M.
Staehlin, P. Focia, T. G. Spiro, J. E. Penner-Hahn, T. V. O’Hallo-
ran, Nat. Chem. Biol. 2008, 4, 107–109.
[9] S. Chandra, R. Kumar, Spectrochim. Acta Part A 2005, 61, 437–
446.
[10] D. A. Nation, M. R. Taylor, K. P. Wainwright, J. Chem. Soc., Dal-
ton Trans. 1992, 1557–1562.
[11] M. K. Taylor, K. D. Trotter, J. Reglinski, L. E. A. Berlouis, A. R.
Kennedy, C. M. Spickett, R. J. Sowden, Inorg. Chim. Acta 2008,
361, 2851–2862.
[12] a) W. Kaim, M. Moscherosch, J. Chem. Soc. Faraday Trans.
1991, 87, 3185–3187; b) W. Kaim, Dalton Trans. 2003, 761–768;
c) S. Ye, W. Kaim, B. Sarkar, B. Schwederski, F. Lissner, T.
Schleid, C. Duboc-Toia, J. Fiedler, Inorg. Chem. Commun. 2003,
6, 1196–1200; d) S. Roy, M. Sieger, P. Singh, M. Niemeyer, J.
Fiedler, C. Duboc, W. Kaim, Inorg. Chim. Acta 2008, 361, 1699–
1704.
[31] M. Krejcik, M. Danek, F. Hartl, J. Electroanal. Chem. 1991, 317,
179–187.
[32] M. Mbuyi, M. Evers, G. Tihange, A. Luxen, L. Christiaens, Tetra-
hedron Lett. 1983, 24, 5873–5876.
[33] A. Spek, J. Appl. Crystallogr. 2003, 36, 7–13.
[34] G. M. Sheldrick, SHELXL97, Program for the Refinement of
Crystal Structures, University of Göttingen: Germany, 1997.
[35] M. J. Frisch, G. Trucks, H. B. Schlegel, G. E. Scuseria, M. A.
Robb, J. R. Cheeseman, G. Scalmani, V. Barone, B. Mennucci,
G. A. Petersson, H. Nakatsuji, M. Caricato, X. Li, H. P. Hratchian,
A. F. Izmaylov, J. Blonio, 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. Mont-
gomery Jr., J. E. Peralta, F. Ogliaro, M. Bearpark, J. J. Heyd, E.
Brothers, K. N. Kudin, V. N. Staroverov, R. Kobayashi, J. Norm-
and, 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, Ö. Farkas, J. B. Foresman, J. V. Ortiz, J. Cioslowski,
D. J. Fox, Gaussion 09, Revision C.01, Gaussian, Inc, Wallingford
CT, 2009.
[13] W. Kaim, M. Sieger, S. Greulich, B. Sarkar, J. Fiedler, S. Zálisˇ,
J. Organomet. Chem. 2010, 695, 1052–1058.
[14] M. W. Blaskie, D. R. McMillin, Inorg. Chem. 1980, 19, 3519–
3522.
[15] C. O. Dietrich-Buchecker, J.-P. Sauvage, J.-M. Kern, J. Am.
Chem. Soc. 1984, 106, 3043–3045.
[16] M. Schwach, H.-D. Hausen, W. Kaim, Chem. Eur. J. 1996, 2,
446–451.
[17] F. Baumann, A. Livoreil, W. Kaim, J.-P. Sauvage, Chem. Com-
mun. 1997, 35–36.
[18] J.-P. Sauvage, Angew. Chem. Int. Ed. 2017, 56, 11080–11093.
[19] C. L. Foster, C. A. Kilner, M. Thornton-Pett, M. A. Halcrow, Acta
Crystallogr., Sect. C: Cryst. Struct. Commun. 2000, 56, 319–320.
[20] a) D. M. Haddleton, A. J. Clark, D. J. Duncalf, A. M. Heming, D.
Kukulj, A. J. Shooter, J. Chem. Soc., Dalton Trans. 1998, 381–
386; b) H. tom Dieck, L. Stamp, Z. Naturforsch. B 1980, 45,
1369–1382; c) L. Stamp, H. tom Dieck, Inorg. Chim. Acta 1978,
129, 107–114; d) H. tom Dieck, I. W. Renk, Chem. Ber. 1971,
104, 92–109.
[36] J. P. Perdew, K. Burke, M. Enzerhof, Phys. Rev. Lett. 1996, 77,
3865–3868.
[21] a) F. Allen, Acta Crystallogr., Sect. C: Cryst. Struct. Commun.
2002, 58, 380; b) I. J. Bruno, J. C. Cole, P. R. Edgington, M.
Kessler, C. F. Macrae, P. McCabe, J. Pearson, R. Taylor, Acta
Crystallogr., Sect. B: Struct. Sci. 2002, 58, 389–397.
[22] a) B. Nowicka, A. Samotus, J. Szklarzewicz, J. Burgess, J. Faw-
cett, D. R. Russell, Polyhedron 1998, 17, 3167–3174; b) J. K.
Burdett, R. Hoffmann, R. C. Fay, Inorg. Chem. 1978, 17, 2553–
2568.
[37] C. Adamo, V. Barone, J. Chem. Phys. 1999, 110, 6158–6170.
[38] P. J. Hay, J. Chem. Phys. 1977, 66, 4377–4384.
[39] K. Raghavachari, G. W. Trucks, J. Chem. Phys. 1989, 91, 1062–
1065.
[40] M. Cossi, N. Rega, G. Scalmani, V. Barone, J. Comput. Chem.
2003, 24, 669–681.
[23] a) J. C. Jeffrey, T. B. Rauchfuss, Inorg. Chem. 1979, 18, 2658–
2666; b) P. Braunstein, F. Naud, Angew. Chem. Int. Ed. 2001, 40,
Received: March 2, 2018
Published online: ᭿
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Journal of Inorganic and General Chemistry
ARTICLE
Zeitschrift für anorganische und allgemeine Chemie
M. Bubrin, H. Kvapilová, J. Fiedler, F. Ehret, S. Zálisˇ,
W. Kaim* ......................................................................... 1–11
Hybrid α-Diimine/Bis(chalcogenoether) Ligands for Copper(I)
and Copper(II) Complexes
Z. Anorg. Allg. Chem. 0000, 0–0
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