Copper(II) thiaethyneporphyrin and copper(II) 21-phosphoryl N-confused porphyrin hybrids. Intramolecular copper(II)-carbon interaction inside of a porphyrinoid surrounding

Article abstract of DOI:10.1021/ic302631d

Stabilization of unusual organocopper(II) species via the very efficient protection of the copper(II)-carbon bond has been achieved encapsulating the copper(II) center in the coordination core of suitably constructed carbaporphyrinoids. Copper(II) was inserted into hybrid N-confused porphyrins which contain 21-diphenylphosphoryl-, 21-diphenylthiophosphoryl-, or 21-phosphinodithioic substituents or into 20-thiaethyneporphyrin, an aromatic porphyrinoid, which combines two structural motifs of 21-thiaporphyrin and ethyne. Two distinctly different types of the copper(II)-carbon bond have been detected. Copper(II) hybrid N-confused porphyrins reveal the η¹-C(21) side-on coordination. The unprecedented equatorial metal(II)?η²-CC interaction has been trapped in a copper(II) thiaethyneporphyrin surrounding.

Full text of DOI:10.1021/ic302631d

Article
pubs.acs.org/IC
Copper(II) Thiaethyneporphyrin and Copper(II) 21-Phosphoryl
N‑confused Porphyrin Hybrids. Intramolecular Copper(II)−Carbon
Interaction Inside of a Porphyrinoid Surrounding
Norbert Grzegorzek, Elzbieta Nojman, Ludmiła Szterenberg, and Lechosław Latos-Grazynski*
́
̇
̇
Department of Chemistry, University of Wrocław, 14 F. Joliot-Curie St., 50-383 Wrocław, Poland
S
* Supporting Information
ABSTRACT: Stabilization of unusual organocopper(II) spe-
cies via the very efficient protection of the copper(II)−carbon
bond has been achieved encapsulating the copper(II) center in
the coordination core of suitably constructed carbaporphyr-
inoids. Copper(II) was inserted into hybrid N-confused
porphyrins which contain 21-diphenylphosphoryl-, 21-diphe-
nylthiophosphoryl-, or 21-phosphinodithioic substituents or
into 20-thiaethyneporphyrin, an aromatic porphyrinoid, which
combines two structural motifs of 21-thiaporphyrin and
ethyne. Two distinctly different types of the copper(II)−
carbon bond have been detected. Copper(II) hybrid N-
confused porphyrins reveal the η1-C(21) side-on coordination. The unprecedented equatorial metal(II)···η2-CC interaction has
been trapped in a copper(II) thiaethyneporphyrin surrounding.
subsequently O-confused porphyrin with a pendant pyrrole.14
INTRODUCTION
■
As a result of steric constraints imposed by the ligand geometry,
the C(21) carbon creates two distinctly different types of the
copper(II)−carbon(21) bonds. Specifically the equatorial
macrocycle may act as an sp2 σ-carboanion to coordinate to
the copper in the η1-fashion, but the coordinating C(21) carbon
atom preserves trigonal geometry. The copper(II)−carbon(sp2)
bond was also found in the nitrogen-anchored N-heterocyclic
carbene complexes.56 It was also possible to stabilize the
copper(II)−carbon(sp3) bond by coordination of the tripoidal
ligand tri(2-pyridylthio)methane (tptmH).57,58 Recently we
have demonstrated that the 21-diphenylphosphoryl-carbapor-
pholactone hybrid stabilized the organocopper(II) complex,
revealing an unprecedented side-on coordination of copper-
(II).17
Here we have focused on organocopper(II) chemistry of two,
recently reported, types of carbaporphyrinoids. Thus the hybrid
carbaporphyrins (1−4) have been formed in the course of
regioselective phosphorylation or thiophosphorylation of N-
confused carbaporphyrin (1−4). They combine features of N-
confused porphyrin and covalently appended diphenylphos-
phoryl, 21-diphenylthiophosphoryl, or 21-phosphinodithioic
units (Chart 1).59 On the other hand 20-thiaethyneporphyrin
5 is an aromatic porphyrinoid that presents the essential
features of [18]triphyrin(4.1.1) combining, however, two
structural motifs of 21-thiaporphyrin60 and ethyne.15
A set of the organometallic derivatives formed by a
combination of metal cations and appropriately tuned
carbaporphyrinoids may serve as a perfect (chemically and
structurally) environment to explore innovative organometallic
chemistry in a “vessel” formed by porphyrin-like surround-
ing.1−7 The remarkable structural flexibility of carbaporphyr-
inoids, including N-confused porphyrin, is reflected by
formation of various coordination modes inside a macrocyclic
frame, with or without formation of a direct metal−carbon
bond.7−22 Atypical oxidation states of metal ions trapped in the
organometallic setting including extremely rare organocopper-
(II) complexes have been identified.14,19,23−30
In fact, the organometallic chemistry of copper is nearly
exclusively focused on the metal oxidation state +1.31−35
Electron-rich organocopper(I) compounds are widely applied
as useful reagents in numerous organic syntheses.33,36 Transient
organocopper(III) species were considered in the mechanism
of a multiple bond activation via reactive π complexes.37−41 The
several stable organometallic complexes of copper(III) were
characterized by X-ray crystallography.29,42−46 Initially the
transient σ-alkyl adducts of copper(II) were postulated to be
formed in the reactions of copper(I) complexes with aliphatic
radicals obtained by pulse-radiolysis techniques.47 A detailed
study covered the key mechanistic aspects of a mild C−H
activation process conducted by a triazamacrocyclic copper(II)
complex revealed an aromatic C−H bond in close proximity to
the metal center.48−53 Eventually organocopper(II) compounds
were synthesized applying an efficient protection of the
copper(II)−carbon bond in the coordination (CNNN) core
of N-confused porphyrin,25,54 N-confused calix[4]phyrin55 and
As a part of our continuing program aimed to explore
organometallic chemistry of paramagnetic carbaporphyri-
Received: December 1, 2012
© XXXX American Chemical Society
A
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Chart 1
Scheme 1. Insertion of Copper(II) to Hybrid N-confused
Porphyrins
a
noids,61 here we report on the synthesis and spectroscopic
characterization of copper(II) complexes of these specific 1−5
carbaporphyrinoids. Copper(II) ions are expected to be suitably
held via three pyrrolic nitrogens (1−4) or two pyrrolic
nitrogens and one thiophenic sulfur atoms (5) in the T-like
fashion. Consequently the inserted copper(II) cation will be
conveniently exposed to interact with the C(21) carbon atom
(1−4) or a conjugated four-carbon linker of porphyrinoid 5.
These studies explore specific macrocyclic factors of importance
in the emerging field of copper(II) organometallic chemistry,
affording an insight into intramolecular copper(II)-carbapor-
phyrinoid interactions.
a
Conditions: Cu(OAc)2, THF, N2.
RESULTS AND DISCUSSION
■
Formation and Characterization of Copper(II) Com-
plexes. Copper(II) has been readily inserted into hybrid
porphyrinoids 1−4 following the procedure reported previously
for analogous derivatives of carbaporpholactone17 to give
copper(II) complexes in which the hybrid porphyrinoids act as
dianionic ligands (Scheme 1).
Insertion of copper(II) cation was accompanied by a color
change of the reaction mixture from green to red in case of 1-
(Cu), 3-(Cu), 4-(Cu) and from orange to green for 2-(Cu).
Solutions of the copper(II) complexes are not reactive toward
dioxygen for several hours. The UV−vis absorption spectra of
copper(II) porphyrinoids demonstrate the similar patterns
consisting of Soret band (slightly broadened for 3-(Cu)) and
two Q bands (Figure 1). The presence of copper(II)
paramagnetic species was confirmed each time by electron
paramagnetic resonance (EPR) spectroscopy (vide infra).
Analogously copper(II) has been inserted into thiaethyne-
porphyrin 5 to give the four coordinated complex of copper(II)
thiaethyneporphyrin 5-(Cu) (Scheme 2).
Figure 1. UV−vis absorption spectra (dichloromethane), 1-(Cu)
(black), 2-(Cu) (blue), 3-(Cu) (red), and 4-(Cu) (green).
Scheme 2. Insertion of Copper(II) to Thiaethyneporphyrin
a
5
20-Thiaethyneporphyrin 5 acts as a dianionic ligand
coordinating through the two nitrogen and one sulfur donor
atoms. To complete the coordination sphere of the metal,
interaction with the ethyne moiety is readily implied (vide
infra). 5-(Cu) is reactive toward dioxygen in solution. The
process results eventually in the complete degradation of
carbaporphyrinoid. Thus all manipulations including chroma-
tography have been carried in anaerobic conditions. The
identity of 5-(Cu) was confirmed by high-resolution mass
spectrometry.
a
Conditions: Cu(AcO)2, THF, N2.
shift of the Soret-like band has been determined for 5-(Cu)
with respect to free base 5.
Molecular Structure of 1-(Cu). The coordinating about
the copper(II) ion is square pyramidal (X-ray analysis), with
the C(21), N(22), N(23), and N(24) atoms occupying the
equatorial positions and the phosphine oxide oxygen atom in
The UV−vis absorption spectrum of 5-(Cu) is presented in
Figure 2. This complex has spectral characteristics that
resemble that reported for 5-(Ni).15 The small hypsochromic
B
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Figure 2. UV−vis absorption spectra (dichloromethane) of 5 (black)
and 5-(Cu) (red).
the apical position. Actually, the appended diphenylphosphoryl
arm creates a peculiar four-membered ring due to simultaneous
coordination of C(21) and oxygen(PO) atoms. The Cu−C(21)
bond length equals 2.154(3) Å which is significantly (0.078 Å)
shorter than one observed for analogous copper(II) 21-
carbaporpholactone (2.232(2) Å)17 but longer once compared
to copper(II) seen in N-confused calix[4]phyrin (2.007(4)
Å),55 copper(II) O-confused porphyrin with a pendant pyrrole
ring (1.939(4) Å),14 and copper(II) coordinated by the
tripoidal ligand (2.001(8) Å).57,58 The markedly longer
distance has been determined for copper(II) and the inner
carbon C(22) (2.698(5) Å) of copper(II) 22-chloro-m-
benziporphyrin.19 Importantly the C(21) atom of 1-(Cu)
approaches the copper(II) ion at a distance much shorter than
the sum of van der Waals radii (3.1 Å) reflecting the formation
of a weak bond.62
Figure 3. Molecular structure of 1-(Cu) (top: perspective view,
bottom: side view with aryl groups omitted for clarity). The thermal
ellipsoids represent 50% probability.
square planar surrounding of the copper(II) ion with three
nitrogen and one carbon donor atoms.14,25 The isotropic 14N
EPR superhyperfine coupling patterns of 1-(Cu), 2-(Cu), 3-
(Cu), and 4-(Cu) indicate a presence of three pyrrolic nitrogen
donor atoms in the first coordination sphere, showing well
resolved splitting into seven lines associated with the
interaction of the electron with three nearly equivalent nitrogen
atoms (Figure 4).
While the three pyrrole rings reside close to a (Cmeso)4 plane,
the N-confused pyrrole is sharply tipped out and the C(21)−P
bond is almost perpendicular to the same plane. The P−
C(21)−Cu bond angle equals 88.5(2)°. Such an architecture
allows coordination to the copper(II) ion in an η1-fashion
through the C(21) carbon atom. The similar side-on
coordination has been considered, based on spectroscopic
evidence only, for copper(II) 2-aza-2-methyl-21-methyl-21-
carbaporphyrin.25 Thus the copper(II) lies significantly out of
the plane of the N-confused pyrrole, with the angle between the
N-confused pyrrole plane and the CuII−C(21) bond being
41.8° (Figure 3). To get a quantitative measure of the
distortion from the idealized geometry around the C(21)
coordination center, the sums of the bond angles have been
analyzed (Σ = C(1)−C(21)−C(4) + C(1)−C(21)−C(P) +
C(4)−C(21)−P). The comparison of experimental (Σ =
335.9°) and idealized tetrahedral (Σ = 328.5°) or trigonal (Σ
= 360°) parameters reveals the marked degree of pyramidal
distortion from the trigonal geometry expected for the ultimate
side-on coordination. Insertion of copper(II) into 1 adjusted
the geometry to accommodate the copper(II) as the trigonal
geometry around C(21) is expected for the free macrocycle.
EPR Spectral analysis. The EPR spectra recorded for 1-
(Cu), 2-(Cu), 3-(Cu), 4-(Cu), and 5-(Cu) provided the
conclusive evidence for the copper(II) oxidation state in all
investigated complexes (Figure 4, Table 1). The values of g and
A tensor components reveal the typical features diagnostic for
the copper(II) electronic structure d9: (dxz)2, (dyz)2, (dxy)2,
The distinct spectroscopic signature has been determined for
copper(II) thiaethyneporphyrin 5-(Cu). In particular the
multiplicity of superhyperfine splitting (quintet) reflects the
presence of two nitrogen donor atoms (Figure 4 E, F). In fact
Cu
the smaller A∥ as compared for instance to copper(II) N-
confused porphyrins can be related to the number of nitrogen
donor atoms in the first coordination sphere. Actually, similar
values have been reported for derivatives of copper(II)
dipyrromethenes where the coordination of two nitrogen
donor atoms was firmly determined.63 The axial coordination of
tetrahydrofuran (THF) to 5-(Cu) yielding 5-(Cu)-THF
(Scheme 3) is clearly detected by the significant modification
of the EPR parameters.
DFT Studies. The principal geometries of copper(II) N-
confused porphyrin hybrids (1-(Cu), 2-(Cu), 3-(Cu), 4-(Cu))
and copper(II) thiaethyneporphyrin 5-(Cu) were subjected to
DFT optimizations at the B3LYP level of theory using the 6-
31G** basis set. The final geometries are shown in Figures 5
and 6. In each case a genuine energy minimum was obtained.
Significantly the DFT optimized structural parameters of 1-
(Cu) are essentially similar to those determined by X-ray
crystallography (Table 2). In the previous report we have
determined that the DFT optimization reproduced satisfactorily
the X-ray molecular structure of nickel(II) and palladium(II)
thiaethyneporphyrin.15 These comparisons add credibility to
2
1
2
2
2
(dz ) , (dx −y
)
(Table 1). The observed values nicely
correspond to those determined for already reported copper-
(II) complexes of carbaporphyrinoids (Table 1) confirming the
C
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Figure 4. EPR spectra of 1-(Cu) (A), 2-(Cu) (B), 3-(Cu) (C), 4-(Cu) (D) (all at toluene/dichloromethane mixture 2/8 v/v, 77 K) and 5-(Cu) (E)
(toluene, 77 K), 5-(Cu)-THF (F) (toluene/THF, 77 K). Insets A′, B′, C′, D′, E′, and F′ present the corresponding isotropic spectra collected at 298
K. Asterisks denote the signal of the quartz radical. Conditions: microwave frequency v = 9.5749 GHz; microwave power 31.7 mW, modulation
amplitude, 5.19 G; modulation frequency 100 kHz.
the geometry of the DFT optimized structure of 2-(Cu), 3-
(Cu), 4-(Cu) and in particular 5-(Cu).
replaced by 21-diphenylphosphoryl-N-confused porphyrin 1-
(Cu).
In each copper(II) hybrid N-confused porphyrin case, the
three pyrrole rings reside close to a (Cmeso)4 plane, the N-
confused pyrrole is sharply tipped out, and the C(21)−P bonds
(1-(Cu), 2-(Cu), 3-(Cu)) or C(21)−S (4-(Cu)) are almost
perpendicular to the same plane (Figure 5). Such an
architecture allows coordination to the copper(II) ion in an
η1-fashion through the C(21) carbon atom.
The bond indices calculated for the Cu···C contact according
to the Wiberg method66 are comparable to Cu−N bond orders
(Table 3). The significant increase of indices has been noted
once 21-diphenylphosphoryl-carbaporpholactone 9-(Cu) was
DFT optimized geometry of 5-(Cu) (Figure 6) reflects the
balance among constraints of the macrocycle ligand, the size of
the copper(II) ion, and the predisposition of the copper(II) for
square planar geometry. The bond length pattern of aromatic 5
is preserved in 5-(Cu). The most notable feature of 5-(Cu) is
the nature of the Cu(II)···C(1), Cu(II)···C(2), and Cu(II)−
S(20) interactions. In fact the coordination mode detected for
copper(II) thiaethyneporphyrin 5-(Cu) does not have a
precedent in the literature. In particular, the acetylene unit
approaches copper(II) at distances much shorter (Cu···C(1)
2.346 Å, Cu···C(2) 2.346 Å) than the expected van der Waals
D
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Table 1. Spin-Hamiltonian Parameters of Copper(II)
Complexes of Carbaporphyrinoids
Cu
Cu
complex
g∥
g⊥
go
A∥
A⊥
AoCu
AoN
a
1-(Cu)
2.159
2.153
2.157
2.144
2.101
2.129
2.034
2.033
2.035
2.032
2.039
2.059
2.075
2.073
2.076
2.069
2.057
2.063
172.0
172.0
170.0
169.0
94.4
26.0
27.5
29.5
28.0
8
40.0
39.0
37.0
75.0
29
13.0
12.0
13.0
12.0
10
a
a
a
b
2-(Cu)
3-(Cu)
4-(Cu)
5-(Cu)
5-(Cu)-
107.4
12
28.4
9
c
THF
6-(Cu)64
7-(Cu)60,65
8-(Cu)63
9-(Cu)17
10-(Cu)14
11-(Cu)25
12-(Cu)25
2.190
2.212
2.272
2.158
2.134
2.190
2.139
2.045
2.051
2.062
2.041
2.029
2.050
2.057
211
2.141
2.130
2.082
2.073
2.110
2.070
159.5
108
70.0
56.2
38.3
30.0
60
9.8
13.7
21.6
13
164.0
154.0
154
25.0
29.0
13
143
37
23
18.3
a
Frozen solution spectra taken at 77 K, isotropic recorded at 298 K.
The solvent used: toluene/dichloromethane mixture (8/2 v/v).
b
c
Toluene. Toluene/THF. Hyperfine constants are in 10−4 cm−1; 6
porphyrin, 7 21-thiaporphyrin, 8 substituted dipyrromethenes, 9 21-
diphenylphosphoryl-carbaporpholactone, 10 O-confused oxaporphyr-
in, 12 N-confused porphyrin, 12 C(21) deprotonated N-confused
porphyrin.
a
Scheme 3. Coordination of THF to 5-(Cu)
Figure 5. DFT (B3LYP/6-31G**) optimized geometries of (A) 1-
(Cu), (B) 2-(Cu), (C) 3-(Cu), and (D) 4-(Cu). Side projections
emphasize the conformations of the macrocycles. Outer hydrogen
atoms and meso-substituents (bottom views) are omitted for clarity.
a
Conditions: THF, N2.
contact (Cu···C 3.1 Å).62 Thus the copper(II) ion interacts
with thiaethyneporphyrin in an η2-fashion engaging the C(1)
and C(2) carbon atoms. The C(18)−C(1)−C(2)−C(3)
butyne moiety is slightly bent toward copper(II) as clearly
reflected by the appropriate bond angles (∠C(18)C(1)C(2) =
∠C(1)C(2)C(3) = 177.6°). The bond lengths C(1)−C(2)
(1.254 Å) and C(2)−C(3)/C(18)−C(1) (1.372 Å) approach
those detected in the free base 5.15 While the thiophene ring is
planar, it is sharply bent out of the plane of the porphyrin. The
shape of the porphyrin resembles that seen in metal(II)
complexes of 21-thiaporphyrins.3,60,67,68 The dihedral angle
between the thiophene plane and the CuN(19)N(21)C(1)-
C(2) plane is 26.2°. This bending opens up the center of the
porphyrin to accommodate the copper(II) and allows the
copper(II) to interact with the thiophene sulfur in a side-on
fashion. The angle between the center of thiophene and the
Cu−S(20) bond is 126.5°. Similar angles are found in
copper(II) 21-thiaporphyrin.69 The Cu−S(20) distance,
2.177(1) Å, is clearly a bonding distance. Thus the thiophene
is σ-bonded to copper(II) through sulfur which has pyramidal
geometry.
Figure 6. DFT (B3LYP/6-31G**) optimized geometry of 5-(Cu).
Projections emphasize the conformations of the macrocycles. Outer
hydrogen atoms and meso-substituents (bottom view) are omitted for
clarity.
examples of typical coordination bonds Cu−N, M−S, and the
metal(II)···η2-C(1)C(2) itself. Evidently, the copper(II)···C(1)
and copper(II)···C(2) interactions have significant bonding
character albeit smaller than simultaneously coordinating
nitrogen atoms and noticeably reduced in comparison with
relevant previously studied 5-(Ni) and 5-(Pd).15
The interaction involving the metal(II) and the ethyne
fragment in 5-(Cu) is of special interest. Comparison of the
Wiberg bond indices is helpful in discussing the copper(II)···η2-
C(1)C(2) interaction. The data gathered in Table 4 provide
Conclusion. The present work offers the spectroscopic
evidence for stabilization of unusual organocopper(II) species
E
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Table 2. Structural Parameters Obtained from DFT Calculations
bond length (Å)
bond angle (deg)
a
compound
Cu−C(21)
Cu−X
Cu−C(21)−P
Cu−C(21)−P−X
Σ
a
a
d
1-(Cu)
2.181
2.451
86.2
88.5
84.0
95.1
85.2
17.5
−22.9
−8.2
339.2
335.9
345.9
332.3
332.7
c
d
d
d
e
1-(Cu)
2.154(3)
2.278
2.547(2)
a
a
b
2-(Cu)
3-(Cu)
2.329
b
2.133
3.138
−33.2
b
4-(Cu)
2.145
2.697
166.6
a
b
c
d
e
X = O. X = S. X-ray data.,17 Σ = C(1)−C(21)−C(4) + C(1)−C(21)−P + C(4)−C(21)−P. Σ = C(1)−C(21)−C(4) + C(1)−C(21)−S +
C(4)−C(21)−S.
Table 3. Wiberg Bond Indices for Copper(II) Hybrid N-confused Porphyrin
compound
Cu−C(21)
Cu−N(22)
Cu−N(23)
Cu−N(24)
Cu−P
Cu−O
Cu−S
1-(Cu)
2-(Cu)
3-(Cu)
4-(Cu)
0.2548
0.2074
0.2721
0.2668
0.1930
0.3064
0.3152
0.2924
0.3229
0.2110
0.2941
0.2964
0.2786
0.3172
0.1921
0.3035
0.3069
0.2911
0.3235
0.2070
0.0553
0.0503
0.0527
0.1294
0.1513
0.1293
a
9-(Cu)17
a
9-(Cu) copper(II) 21-diphenylphosphoryl-carbaporpholactone.
inoids: 5,10,15,20-tetratolyl-2-aza-21-diphenylphosphoryl-21-carbapor-
phyrin59 1; 5,10,15,20-tetratolyl-2-aza-3,21-bis(diphenylphosphoryl)-
21-carbaporphyrin59 2; 5,10,15,20-tetratolyl-2-aza-21-diphenylthio-
phosphoryl-21-carbaporphyrin59 3; 5,10,15,20-tetratolyl-2-aza-21-car-
baporphyrino-21-diphenylphosphinodithioate59 4; and 3,18-diphenyl-
8,13-di-p-tolyl-20-thiaethyneporphyrin15 5 were prepared by previ-
ously reported methods.
Table 4. Wiberg Bond Indices for 20-Thiaethyneporphyrin
Complexes
complex
bond
5-(Cu)
5-(Ni)15
5-(Pd)15
515
M−C1
M−C2
0.1036
0.1036
0.2973
0.2973
0.3490
1.3809
2.2005
1.3809
0.1589
0.1589
0.3888
0.3888
0.5514
1.3681
2.1604
1.3681
0.1649
0.1650
0.4700
0.4700
0.6329
1.4201
2.0097
1.4201
Copper(II) 5,10,15,20-Tetratolyl-2-aza-21-diphenylphosphoryl-
21-carbaporphyrin 1-(Cu). A 11.4 mg portion (0.013 mmol) of 1
was dissolved in 25 mL of freshly distilled THF, and 12 mg (0.065
mmol) of (AcO)2Cu was added. The green reaction mixture
immediately turned to brown-red. The mixture was stirred at 293 K
for 1 h. Subsequently the solvent was removed, and the dry crude
residue was dissolved in CH2Cl2 and filtered to remove copper(II)
salts. Next, the solvent was removed, and the residue was
chromatographed on basic alumina G(IV) column. The strong red
fraction eluted with dichloromethane was collected and recrystallized
from dichloromethane/n-hexane to give 1-(Cu) (9 mg of red
amorphous solid). Yield: 75%. UV−vis (CH2Cl2, λmax [nm], log ε):
346 (4.51), 447 (4.97), 554 (4.03), 761 (3.62). HR-MS (ESI+, FT-
MS): m/z [M+H]+ 932.2727, calcd for C60H46CuN4OP+ 932.2700.
Copper(II) 5, 10, 15, 20-Tetratolyl-2-aza-3, 21-bis-
(diphenylphosphoryl)-21-carbaporphyrin 2-(Cu). A 8.2 mg portion
(0.008 mmol) of 2 was dissolved in 25 mL of freshly distilled THF,
and 10 mg (0.04 mmol) of (AcO)2Cu was added. The red-orange
reaction mixture turned slowly green. The mixture was stirred at 293 K
for 1 h. Subsequently the solvent was removed, and the dry crude
residue was dissolved in dichloromethane and filtered to remove
copper(II) salts. Next the solvent was removed, and the residue was
chromatographed on a basic alumina G(IV) column. The strong green
fraction eluted with ethyl acetate was collected and recrystallized from
dichloromethane/n-hexane to give 2-(Cu) (7.5 mg of red amorphous
solid). Yield: 85%. UV−vis (CH2Cl2, λmax [nm], log ε): 352 (4.46),
454 (4.83), 628 (4.03), 762 (3.59). HR-MS (ESI+, FT-MS): m/z [M
M−N19
M−N21
M−S20
C18−C1
C1−C2
C2−C3
1.4475
2.2621
1.4475
encapsulated in the coordination core of suitably constructed
carbaporphyrinoids. As a result of steric constraints imposed by
the ligand geometry, two distinctly different types of the
copper(II)−carbon bond have been explored. Thus hybrid N-
confused porphyrin containing diphenylphosphoryl, 21-diphe-
nylthiophosphoryl, or 21-phosphinodithioic substituents reveal
η1-C(21) side-on coordination. In terms of characterization of
intermediates involved in selective C−H(X) bond activation by
copper under mild conditions, the molecular structure of 4
provides a structural model of the copper(II)-C-H(X) transient
species.19,50,51,53,70 Thiaethyneporphyrin-aromatic porphyri-
noid, which combines two structural motifs of 21-thiaporphyrin
and ethyne, affords a unique opportunity to detect
unprecedented copper(II)···η2-CC interactions. In contrast
alkene and alkyne coordinations to copper(I) center in an η2-
fashion have been well documented in the literature.71−74
Significantly the CC unit is located in the plane defined by the
remaining three donor atoms. Evidently carbaporphyrinoids
provide a stimulating environment to explore specific issues of
organometallic chemistry applying the macrocyclic platform
concept as the suitable approach.
+
+H]+ 1132.3060, calcd for C72H55CuN4O2P2 1132.3091.
Copper(II) 5,10,15,20-Tetratolyl-2-aza-21-diphenylthiophosphor-
yl-21-carbaporphyrin 3-(Cu). Nine milligrams (0.010 mmol) of 3 was
dissolved in 25 mL of freshly distilled THF, and 10 mg (0.05 mmol) of
(AcO)2Cu was added. The green reaction mixture turned slowly
brown-red. The mixture was stirred at 293 K for 1 h. Subsequently the
solvent was removed, and the dry crude residue was dissolved in
dichloromethane and filtered to remove copper(II) salts. Next the
solvent was removed, and the residue was chromatographed on basic
alumina G(IV) column. The strong red fraction eluted with
dichloromethane/ethyl acetate (v/v 9/1) was collected and recrystal-
lized from dichloromethane/n-hexane to give 3-(Cu) (8 mg of red
EXPERIMENTAL SECTION
■
Solvents and Reagents. Ethyl acetate and hexane were used
without purification. CH2Cl2 was distilled over CaH2. THF was
distilled over sodium with benzophenone as oxygen presence indicator
in argon atmosphere. (AcO)2Cu was used as received. Carbaporphyr-
F
dx.doi.org/10.1021/ic302631d | Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
amorphous solid). Yield: 85%. UV−vis (CH2Cl2, λmax [nm], log ε):
344 (4.52), 456 (4.84), 560 (4.04), 780 (3.62). HR-MS (ESI+, FT-
MS): m/z [M+H]+ 948.2463, calcd for C60H46CuN4PS+ 948.2471.
Copper(II) 5,10,15,20-Tetratolyl-2-aza-21-carbaporphyrino-21-
diphenylphosphino-dithioate 4-(Cu). Seven milligrams (0.008
mmol) of 4 was dissolved in 25 mL of freshly distilled THF, and 8
mg (0.04 mmol) of (AcO)2Cu was added. The green reaction mixture
turned slowly brown-red. The mixture was stirred at 293 K for 1 h.
Subsequently the solvent was removed, and the dry crude residue was
dissolved in dichloromethane and filtered to remove copper(II) salts.
Next the solvent was removed, and the residue was chromatographed
on basic alumina G(IV) column. The strong brown fraction (red in
solution) eluted with dichloromethane was collected and recrystallized
from dichloromethane/n-hexane to give 4-(Cu) (8 mg of red
amorphous solid). Yield: 95%. UV−vis (CH2Cl2, λmax [nm], log ε):
347 (4.43), 449 (4.77), 555 (3.94), 805 (3.51). HR-MS (ESI+, FT-
AUTHOR INFORMATION
Corresponding Author
*Tel: +48 71 3757256. Fax: +48 71 3282348. E-mail:
lechoslaw.latos-grazynski@chem.uni.wroc.pl. Homepage:
http://llg.chem.uni.wroc.pl.
■
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
Financial support from the Ministry of Science and Higher
Education (Grant N N204 013536) is kindly acknowledged.
Quantum chemical calculations have been carried out at the
Poznan Supercomputer Center (Poznan) and Wrocław Super-
́ ́
computer Center (Wrocław).
+
MS): m/z [M+H]+ 980.2162, calcd for C60H46CuN4PS2 980.2192.
Copper(II) 3,18-Diphenyl-8,13-di-p-tolyl-20-thiaethyneporphyrin
5-(Cu). Copper(II) insertion and chromatography were carried in the
inert atmosphere of the MBraun glovebox using degassed solvents.
Ten milligrams (0.016 mmol) of 5 was dissolved in 10 mL of THF,
and 32 mg (0.16 mmol) of (AcO)2Cu was added. Reaction mixture
slowly turned from orange to brown-red. The mixture was stirred at
229 K for 3 h. Subsequently the solvent was removed under vacuum,
and the dry crude residue was chromatographed on silica gel. The first
light-brown fraction eluted with dichloromethane contained 5-(Cu).
The second fraction eluted with dichloromethane/THF (9:1, v/v)
yielded the mixture of 5-(Cu) and its THF adduct as confirmed by
EPR. Yield of 5-(Cu): 20%. UV−vis (CH2Cl2, λmax [nm]): 437. HR-
MS (ESI+, TOF-MS): m/z M•+ 681.1424, calcd for [C44H30N2SCu]•+
681.1420.
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