Nickel(II) and palladium(II) thiaethyneporphyrins. intramolecular metal(II)-η2-CC interaction inside a porphyrinoid frame

Article abstract of DOI:10.1021/ic2027175

3,18-Diphenyl-8,13-di-p-tolyl-20-thiaethyneporphyrin ([18]thiatriphyrin(4. 1.1)), which formally contains an C1-C2 ethyne moiety instead of pyrrole embedded in the macrocyclic framework of 21-thiaporphyrin, was obtained in a modification of the "3 + 1" ap

Full text of DOI:10.1021/ic2027175

Article
pubs.acs.org/IC
Nickel(II) and Palladium(II) Thiaethyneporphyrins. Intramolecular
Metal(II)−η2-CC Interaction inside a Porphyrinoid Frame
Elzbieta Nojman, Anna Berlicka, Ludmiła Szterenberg, and Lechosław Latos-Grazynski*
́
̇
̇
Department of Chemistry, University of Wrocław, 14 F. Joliot-Curie Street, 50-383 Wrocław, Poland
S
* Supporting Information
ABSTRACT: 3,18-Diphenyl-8,13-di-p-tolyl-20-thiaethynepor-
phyrin ([18]thiatriphyrin(4.1.1)), which formally contains an
C1−C2 ethyne moiety instead of pyrrole embedded in the
macrocyclic framework of 21-thiaporphyrin, was obtained in a
modification of the “3 + 1” approach using the ethyne analogue
of tripyrrane (1,4-diphenyl-1,4-di(pyrrol-2-yl)but-2-yne) and 2,5-
bis(p-tolylhydroxymethyl)thiophene. The spectroscopic and struc-
tural properties of 20-thiaethyneporphyrin reflect its macro-
cyclic aromaticity, revealing a combination of the acetylene
(≥C−CC−C≤) and cumulene (>CCCC<) character
of the C18−C1−C2−C3 linker. The magnetic manifestations of aromaticity and antiaromaticity of thiaethyneporphyrin and its
1
two-electron-oxidized derivative were observed using H NMR spectroscopy and were confirmed by density functional theory
calculations involving chemical shifts and nucleus-independent chemical shift analysis. Protonation of 20-thiaethyneporphyrin
yielded a nonaromatic tautomer of iso-20-thiaethyneporphyrin, locating the saturated meso carbon adjacent to thiophene.
Insertion of palladium(II) and nickel(II) into 20-thiaethyneporphyrin afforded planar palladium(II) thiaethyneporphyrin and
low-spin diamagnetic nickel(II) 20-thiaethyneporphyrin as determined by X-ray crystallography. 20-Thiaethyneporphyrin acts
as a dianionic ligand that coordinates through the two nitrogen and one sulfur donors. Metal(II) ions are uniquely exposed to
form an intramolecular metal(II)−η2-CC bond, whereas the organometallic fragment is coplanar with the whole macrocycle.
Coordination of pyridine converts diamagnetic nickel(II) thiaethyneporphyrin into its paramagnetic counterpart as determined
1
by H NMR.
building block may be of importance in the construction of
porphyrinoids derived formally from [14]triphyrins(n.1.1).11,12
Developments in the area of contracted porphyrinoids related
to [14]triphyrins(1.1.1) (Chart 2), such as subphthalocyanine,13
subporphyrazine,14 subporphyrin,15−17 and subpyriporphyrin 3,18
have been motivated by their potential applications in the fields
of dyes, nonlinear optics, photonic devices, and materials
sciences.19−23 The recent progress is associated with the
dynamically developing exploration of [N]triphyrins(n.1.1) includ-
ing the seminal for the field of boron(III) [14]triphyrins(1.1.1)
2.15−17,24 Still, with the exception of subpyriporphyrin 3, a
homologue of [14]triphyrin(1.1.1) with a pyridine moiety
embedded in the macrocyclic framework, all [14]triphyrins(1.1.1)
were isolated as boron(III) complexes, which were typically applied
as indispensable templating agents.18,24 Preserving the fundamental
features of subporphyrins, one can envisage the systematic
modification of triphyrin(1.1.1), which requires elongation of the
meso bridge (bridges). The replacement of nitrogen(s) by
heteroatom(s) should also be considered. Accordingly, a group
of aromatic β- and meso-substituted [14]triphyrins(2.1.1) and
[14]benzotriphyrins(2.1.1) 4, which are nearly planar metal-free
contracted porphyrinoids, have recently been reported.24−28
INTRODUCTION
■
Incorporation of an acetylene−cumulene unit into a porphy-
rinoid skeleton provides the unique means to design a
molecular frame affording eventually effective control of the
electronic structure that encloses the π-conjugation pathway of
aromatic molecules. Originally, the annulene−cumulene
moieties have been successfully embedded into porphyrinoids,
heteroporphyrinoids, or expanded porphyrinoids, furnishing
the specific subgroup of expanded porphyrinoids,1−10 the
representative examples of which include acetylene−cumulene
porphycene 1 (Chart 1).1
Chart 1
Exploration in this area can be motivated by the search for
suitable chromophores potentially active at near-IR (NIR)
because of the expanded π-conjugation pathway. Recently, we
recognized that the concept of an acetylene−cummulene
Received: December 19, 2011
Published: February 22, 2012
© 2012 American Chemical Society
3247
dx.doi.org/10.1021/ic2027175 | Inorg. Chem. 2012, 51, 3247−3260

Inorganic Chemistry
Article
Chart 2
Chart 4
RESULTS AND DISCUSSION
Synthesis of 1,4-Di(phenyl-1,4-di(pyrrol-2-yl)but-2-
yne (11). A key step in the synthesis of 3,18-diphenyl-8,13-
di-p-tolyl-20-thiaethyneporphyrin 7 is the construction of 11,
which is a suitable synthon for introducing the ethyne unit into
a porphyrin-like skeleton (Scheme 1).
■
The replacement of the six inner protons of [18]annulene by three
oxygen, sulfur, or NH(NR) groups or some combination of the
three, as explored originally by Badger et al., leads to heteroatom-
bridged annulenes related to [18]triphyrin(2.2.2).29−31 Aza-
deficient porphyrin 5,10,15,20-tetraaryl-21-vacataporphyrin [buta-
dieneporphyrin or [18]triphyrin(6.1.1)], which is an annulene−
porphyrin hybrid, can be also considered as a representative
molecule for the whole subclass of homologous [N]triphyrins-
(n.1.1).32−34
a
Scheme 1. Synthesis of 11 (30%)
In the search for contracted porphyrinoids (heteroporphy-
rinoids) structurally related to putative [18]triphyrin(4.1.1),
one can refer to two formal strategies where the final structure
is being treated as derived from [14]triphyrin(1.1.1) or
[18]porphyrin(1.1.1.1). Formally, [18]triphyrin(4.1.1) could
be derived from [14]triphyrin(1.1.1) or [18]porphyrin(1.1.1.1)
using the expansion (C3 insertion) or replacement (pyrrole
with −CC−) concepts.35 Of course, in the present case, these
hypothetical changes in the major skeleton must be accom-
panied by heteroatom(s) substitution and reduction.
Previously, we have probed such a strategy to obtain
19,21-dithiaethyneporphyrin (Chart 3) and, subsequently,
the first contracted carbaporphyrinoid−dithiaethyneazulipo-
rphyrin 6.11,12
a
Legend: (a) Co2(CO)8; (b) pyrrole, TFA; (c) Fe(NO3)3·9H2O;
Co′ = Co(CO)3.
1,4-Diphenyl-2-butyne-1,4-diol 8 has been obtained by
applying the standard approach in the reaction of aryl aldehyde
(benzaldehyde) with the Grignard reagent BrMgCCMgBr in
tetrahydrofuran (THF).36,37 Subsequently, the modified
Nicholas reaction has been applied as shown in Scheme 1.
The seemingly straightforward approach, i.e., a direct reaction
between 8 and pyrrole (in excess) catalyzed with trifluoroacetic
acid (TFA), failed to produce 11. Complexation of an alkyne to
dicobalt hexacarbonyl has been typically used to help stabilize
the carbocationic charge generated at the carbon α to the
alkyne moiety prior to treatment with a nucleophile. For
instance, stable carbocationic intermediates that benefit from
the β-effect of cobalt have been alkylated with several carbon
nucleophiles to result in C−C bond formation.38−44 Thus, 8
stirred with Co2(CO)8 in THF with the subsequent evolution
of carbon monoxide gas afforded a stable dark-red complex 9
between the alkyne and dicobalt hexacarbonyl. Complex 9 was
then treated with TFA to form a propargylic cation stabilized
by the adjacent cobalt carbonyl moiety. The subsequent reac-
tion with pyrrole as a nucleophile followed by decomplexation
afforded a substituted alkyne 11 (yield 30%).
Chart 3
The coordinating abilities of 5 and 6 were exemplified by the
formation of their ruthenium(II) complexes.
In the present work, we describe the synthesis and reactivity
of a new porphyrinoid 20-thiaethyneporphyrin 7 (Chart 4),
which, while 21-thiaporphyrin-like in character, is expected to
have fundamentally different electronic and coordination proper-
ties. Eventually, the ability to coordinate nickel(II) and palladium-
(II), yielding the T-frame of coordinated metal(II) ions uniquely
exposed to interact with the π CC bond, has been explored.
The molecular structure of 11 was determined by X-ray
diffraction studies; the graphic representation is shown in
Figure 1. The C2−C3 bond length [1.188(2) Å] reflects the
3248
dx.doi.org/10.1021/ic2027175 | Inorg. Chem. 2012, 51, 3247−3260

Inorganic Chemistry
Article
Figure 2. UV−vis absorption spectra (298 K, CH2Cl2) of 7 (black
line) and [13-H2]2+ (red line). Inset: Q bands of 7.
Figure 1. Molecular structure of 11 (top, perspective view; bottom,
side view). The thermal ellipsoids represent 50% probability. Selected
bond lengths: C1−C2, 1.478(2) Å; C2−C3, 1.188(2) Å; C3−C4,
1.483(2) Å.
ethyne structure of 11. Accordingly, the characteristic 13C
resonance of ethyne (83.4 ppm) has been detected at 13C NMR.
Synthesis and Characterization of 7. 20-Thiaethynepor-
phyrin 7 has been obtained in a simple modification of the
“3 + 1” approach10,45 described for p-benziporphyrin,10,46,47 24-
thia-1,4-naphthiporphyrin,10,48 expanded p-benziporphyrins48,49
and heterocarbaporphyrins11,48−50 using the ethyne analogue of
tripyrrane 11 (Scheme 2).
a
Scheme 2. Synthesis of 7 (33%)
1
Figure 3. H NMR spectra of (A) 7 (CDCl3, 300 K), (B) 12′-H+
a
Legend: (a) BF3:OEt2; (b) Et3N, DDQ.
(CD2Cl2, 300 K), and (C) [13-H2]2+ (CDCl3, 300 K). Peak labels
follow systematic position numbering or denote proton groups: o-, m-,
p-Ph are the ortho, meta, and para positions of the meso-aryl groups.
Inset: pyrrole region of 7. Resonance assignments at trace B: pyrr,
pyrrole; th, thiophene. The broad resonance centered at 7.5 ppm in
traces B and C is tentatively assigned to the unidentified products of
oxidation.
The electronic spectrum of 7 (Figure 2) demonstrates a distinct
intense Soret-like band at 439 nm accompanied by less intense Q
bands at 508, 539, 630, and 710 nm, resembling the spectroscopic
features of aromatic 5,10,15,20-tetraphenyl-21-thiaporphyrin.51
The 1H NMR spectrum of 7 presents resonances at positions
consistent with an aromatic structure and resembles that of
21-thiaporphyrin (Figure 3, trace A).51 Assignments of the H
1
retains the macrocyclic aromaticity, reflecting the presence of
an 18-π-electron delocalization pathway. The scalar coupling
detected between 19,21-NHs and β-pyrrolic hydrogen atoms
confirms the molecular structure of 7.
and 13C NMR resonances for 7 have been made on the basis of
relative intensities and detailed two-dimensional NMR experi-
ments (COSY, NOESY, HSQC, and HMBC). The molecule 7
3249
dx.doi.org/10.1021/ic2027175 | Inorg. Chem. 2012, 51, 3247−3260

Inorganic Chemistry
Article
The 13C chemical shifts of a four-carbon linker derived from
2-butyne are equal to 117.9 ppm for C1 and C2 and 102.3 ppm
for C3 and C18. Two canonical structures of 7 define 18-π-
electron macrocyclic delocalization pathways (Scheme 3). The
Scheme 3. Canonical Structures of 7
cumulene segment itself of 7-2 contributes four π electrons
(rather than six) because of the perpendicular orientation of the
p orbitals that make up the central π bond.
Accordingly, the electronic structure of 7 can be described as
reflecting a combination of the acetylene (≥C−CC−C≤)
Figure 4. Molecular structure of 7 (top: perspective view; bottom: side
and cumulene (>CCCC<) character of the C18−C1−
C2−C3 fragment. The relevant chemical shift values of
acetylene or cumulene carbon atoms adjacent to aryl or
2-thienyl moieties have been considered in comparisons. The
Csp carbon atoms of 11 produces a 13C NMR resonance at 83.4
ppm, in the 70−95 ppm range typical for acetylene. The 13C
NMR chemical shifts of cumulene fragments vary in the relatively
wide range: 140.53 ppm for tetra(2-thienyl)butatriene,52 152.03
ppm for tetraphenylbutatriene,53 and 134.48 ppm for 6,7,18,19-
tetradehydrotetrathia[24]annulene(4.0.4.0), where, however, some
admixture of the acetylenic structure was suggested.4 Thus, the 13C
NMR chemical shifts of 7 point out that 7-1 and 7-2 contribute to
the overall electronic structure, although the cumulenic character of
the C18−C1−C2−C3 moiety prevails. The detected chemical
shifts of 7 are fairly typical for acetylene−cumulene porphyr-
inoids1,2,53 and acetylene−cumulene annulenes54 and resemble that
determined for 19,21-dithiaethyneporphyrin 5.11
view with aryl groups omitted for clarity). The vibrational elipsoids
represent 50% probability. The bond lengths in the Csp CspCspCsp
(C18−C1−C2−C3) unit are 1.380(2), 1.238(2), and 1.385(2) Å. The
dihedral angles between the plane of four meso-carbon atoms (C3, C8,
C13, and C18) and the planes of five-membered rings are as follows:
pyrrole 18.3°, thiophene 16.5°, and pyrrole 16.1°.
2
2
been considered as a feasible route to generating novel
macrocyclic forms. Thus, titration of 7 with HBF4 etherate or
TFA has been carried out in dichloromethane-d2 (298 K). The
progress of this reaction has been systematically monitored by
1
1H NMR. Judging by the H NMR spectra of the reaction
mixture, the process is quite complex. In the conditions of the
experiment, the protonation is not reversible. The transient
species 12′-H readily undergoes unexplored degradation,
yielding the broad peak centered at 7.5 ppm (Figure 3, trace B).
Still, the positions of the narrow resonances including the NH
ones reflect the structural features of 12′-H+ shown in Scheme 4.
The molecular structure of 7, determined in a X-ray diffraction
2
2
study, is shown in Figure 4. The Csp CspCspCsp butyne moiety is
practically linear [C18−C1−C2, 178.5(1)°; C1−C2−C3,
179.2(2)°]. In comparison to 11, which can be considered
here as a standard acetylene-like reference, the statistically
significant shortening of the C18−C1/C2−C3 (0.10 Å) bond
distance and elongation of the C1−C2 (0.05 Å) bond distance
have been detected. This observation firmly reflects the essen-
tial role of cumulene contributor 7-2 in the description of 20-
thiaethyneporphyrin.
Scheme 4. Protonation of 7
The bond distances within the framework of 7 indicate that
the macrocycle reveals the bond-length pattern expected for
aromatic porphyrinoids.10,55 In particular, the C18−C1 and
C2−C3 distances [1.380(2) and 1.385(2) Å] approach the
aromatic bond limit. The aromaticity of 7 is clearly
demonstrated by equalization of the Cα−Cmeso bond lengths
[C2−C3, 1.385(2) Å; C3−C4, 1.420(2) Å; C7−C8, 1.428(2) Å;
C8−C9, 1.402(2) Å]. There is an appreciable effect of the
conjugation on the thiophene fragment. The bond lengths
within the thiophene ring are altered. Thus, the Cα−Cβ bonds
in 7 [1.421(2) and 1.418(2) Å] are longer than the Cβ−Cβ
distances [1.377(2) Å], whereas the reverse is true for tetra-
thiaporphyrinogen.56
1
The H NMR resonances of 12′-H+ were detected in the region
that is typical for the conjugated but nonaromatic system.11,57,57,58
The 1H NMR chemical shift of H8 equals 5.5 ppm and is consistent
with tetrahedral hybridization around the adjacent meso-carbon.58 In
the COSY map, this resonance revealed the scalar coupling to the
thiophene H10, which allowed the unambiguous determination of
the protonation site. Actually, a macrocyclic structural motif present
at 12′-H+ can be identified as one of two nonaromatic 12′ and 12″
tautomers of iso-thiaethyneporphyrins with a saturated meso-carbon,
shown schematically in Chart 5.
Formation of iso-Thiaethyneporphyrin. The addition of
an appropriate electrophile to the evidently electron-rich 7 has
3250
dx.doi.org/10.1021/ic2027175 | Inorg. Chem. 2012, 51, 3247−3260

Inorganic Chemistry
Article
a
Scheme 6. Insertion of Metal(II) to Thiaethyneporphyrin 7
Chart 5. Hypothetical iso-Thiaethyneporphyrins
a
Reaction conditions: 7-Pd, Pd(OAc)2 (10 equiv), toluene, reflux, 4 h,
60%; 7-Ni, Ni(OAc)2·4H2O (10 equiv), toluene, reflux, 5 h, 50%.
Oxidation of 7. Cyclic voltammetry (Figure S6 in the
Supporting Information) demonstrates that 7 undergoes two
consecutive, reversible one-electron oxidations with semireversible
half-wave potentials (1) −74 mV and (2) +202 mV (if the half-
wave potential of ferrocene equals 0 mV), yielding 7•+ and
[13-H2]2+, respectively (Scheme 5). These potentials are very low,
which accounts for the easy accessibility of the oxidized forms.
ligand coordinating through the two nitrogen and one sulfur
donors. To complete the coordination sphere of metal, inter-
action with the ethyne moiety is required (vide infra).
7-Pd is stable in solution and can be chromatographed.
Solutions of 7-Ni undergo gradual demetalation to give free
thiaethyneporphyrin 7. Originally, the identity of 7-M was
confirmed by high-resolution mass spectrometry (HR-MS) and
NMR spectroscopy. The electronic absorption spectra of 7-Pd
and 7-Ni are presented in Figure 5. These complexes have
Scheme 5. Oxidation of 7
Oxidation of 7 in chloroform-d or dichloromethane-d2 with
varying amounts of 2,3-dichloro-5,6-dicyano-p-benzoquinone
(DDQ) has been followed by 1H NMR. In fact, the addition of
DDQ resulted in extreme broadening of all resonances prac-
tically beyond detection. Presumably, the presence of even a
minute amount of the radical 7•+ leads to significant line
broadening and shortening of the T1 relaxation times, confirming
fast electron exchange between differently oxidized forms of 7.59
Finally, in this condition oxidation resulted in the irreversible
degradation of 7. The analogous oxidation of 7 with DDQ in
chloroform-d or dichloromethane-d2 but in the presence of HBF4
Figure 5. UV−vis absorption spectra (298 K, CH2Cl2) of 7 (blue
line), 7-Pd (black line), 7-Ni (red line), and 14-Pd (green line).
1
afforded a well-resolved H NMR spectrum readily assigned to
[13-H2]2+, the diprotonated form of [16]thiaethyneporphyrin
(Figure 3, trace C). During oxidation, the color of the solution
changes from orange to brown-red. The UV-Vis electronic spec-
trum (Figure 2) presents the features assigned to antiaromaticity.
spectral characteristics that resemble those of thiaethynepor-
phyrin. The marked bathochromic shift of the Soret-like band
has been determined for 7-Pd.
7-Pd and 7-Ni have effective Cs symmetry, with the mirror
plane passing through the metal ion, thiophene sulfur, and the
center of the C1−C2 bond. As a consequence, the representa-
tive 1H NMR spectrum of 7-Pd (Figure 6, trace A) contains the
AB pattern of pyrrole resonances accompanied by the thio-
1
The H chemical shifts observed for [13-H2]2+, in particular the
peculiar upfield position of the inner H19 and H21 hydrogen
atoms (25.35 ppm), show that a paratropic ring current is present
in the macrocycle (Figure 3, trace C). The antiaromatic behavior is
also reflected by the reverse order of meso-aryl resonances (p-H >
m-H > o-H).33 In particular, the upfield relocation of the ortho
protons (phenyl 6.6, p-tolyl 6.8 ppm) seems to be of significance.
The pyrrolic β-H signals of [13-H2]2+ at 5.96 and 6.08 ppm are
slightly shifted upfield relative to the nonaromatic fully conjugated
systems, which contain pyrrole moieties.57,60 The resonances of
[13-H2]2+ disappeared after the addition of pyridine-d5 to the
NMR sample. The addition of HBF4 resulted in the recovery of
[13-H2]2+.
Formation and Characterization of Palladium(II) and
Nickel(II) Complexes. Palladium(II) and nickel(II) have been
inserted into thiaethyneporphyrin to give formally four-
coordinated complexes of palladium(II) thiaethyneporphyrin
7-Pd and low-spin diamagnetic nickel(II) thiaethyneporphyrin
(Scheme 6). The 20-thiaethyneporphyrin 7 acts as a dianionic
1
phene singlet resembling closely the H NMR spectrum of 7.
The insertion of palladium resulted also in rather modest
changes in the 13C chemical shift. The 13C chemical shifts of
a four-carbon linker derived from 2-butyne are equal to
115.8 ppm for C1 and C2 and 107.2 ppm for C3 and C18 and
are practically identical with those for the free base 7.
Nonequivalence of two macrocyclic sides due to the side-on
coordination of the thiophene of 7-M causes each aryl ring to
have two distinct ortho and two meta resonances, unless the
rotation around the Cmeso−Cipso bond is sufficiently fast.
Significantly, meso-tolyls of 7-Pd, flanking the thiophene unit,
demonstrate two o-H resonances typical for the slow rotation
limit even at 300 K. At same time, the averaged features of
meso-phenyl resonances have been seen. As the temperature is
lowered, these meta and ortho resonances are splitting because
3251
dx.doi.org/10.1021/ic2027175 | Inorg. Chem. 2012, 51, 3247−3260

Inorganic Chemistry
Article
H2 position. The formation of 14-Pd from 7-Pd can be described
as the stereoselective anti-addition of palladium(II) and a hydride
anion across the C1−C2 multiple bond. Formally, at the free base
level, this transformation can be treated as an anti-addition of
dihydrogen to thiaethyneporphyrin, yielding still aromatic
20-thiaetheneporphyrin 14 (Chart 6).
Chart 6
Initially, the analogous reactivity of 7-Ni toward NaBH4 such
as that determined for 7-Pd has been expected. The appropriate
experiments followed by NMR led to the conclusion that
demetalation might take place.
Formation of High-Spin Nickel(II) Species. Titration of
7-Ni with pyridine converted the low-spin species into the high-
spin complex 7-Ni-py due to axial coordination (Scheme 8).
Scheme 8. Coordination of Pyridine to 7-Ni
1
Figure 6. H NMR spectra: (A) 7-Pd (CDCl3, 282 K); (B) 7-Ni
(CDCl3, 300 K); (C) 14-Pd (180 K, CD2Cl2). The residual resonances
of 7 are marked with asterisks.
of the slower rotation rate. The fast rotation of all meso-aryls
has been detected for 7-Ni at 300 K.
Reaction with Borohydride. 7-Pd reacts with sodium
borohydride to produce aromatic palladium(II) thiaethenepor-
phyrin (Scheme 7).
The paramagnetic nickel(II) complex is readily identified by 1H
NMR (Figure 7). The spectrum resembles closely the pattern
Scheme 7. Formation of 14-Pd
The progress of transformation from 7-Pd to 14-Pd has been
directly followed by 1H NMR (Figure 6, trace C) in conditions
that afforded the best spectroscopic insight (i.e., 300 K, in
dichloromethane-d2 adding NaBH4 in ethanol). Any attempt to
1
isolate 14-Pd failed. The H NMR spectrum of 14-Pd reflects
symmetry lowering in comparison to 7-Pd. Two pyrrolic and
one thiophene AB patterns and the unique H2 resonance can
be easily identified. The C2 carbon atom of 14-Pd produces a
resonance at 122 ppm, which is consistent with its trigonal geo-
metry. Thus, the PdII−η2-C1C2 interaction has been replaced by
the typical PdII−C σ bond (Pd−C1), affording the complex of a
regular carbaporphyrinoid. Thus, the reaction with NaBH4 can be
considered as a specific case of 7-M reactivity. The deuterated
derivative where a deuterium atom is bound to C2 has been
synthesized as described above by replacing NaBH4 in ethanol
with NaBD4 in methanol-d4. The deuteration has resulted in the
removal of the singlet at 8.76 ppm unambiguously assigned to the
1
Figure 7. H NMR spectrum of 7-Ni after the addition of (A) 0.25
equiv of pyridine-d5 and (B) 0.25 equiv of pyridine (600 MHz, 200 K,
CD2Cl2). Resonance assignments: pyrr, pyrrole; th, thiophene; H3,
H4, protons of coordinated pyridine.
characteristic for paramagnetic nickel(II) thiaporphyrin with
the upfield shift of the thiophene resonance and a large
difference in contact shifts of downfield pyrrole resonances for
β-H located in the same pyrrole ring.57,60−62
3252
dx.doi.org/10.1021/ic2027175 | Inorg. Chem. 2012, 51, 3247−3260

Inorganic Chemistry
Article
The axial coordination of pyridine has been clearly confirmed
by the detection of H3 and H4 resonances assigned readily
by comparison of the NMR spectra collected for 7-Ni-py and
7-Ni-py-d5. Two resonances of the two axially coordinated
pyridines, located in the positions determined above, resemble
those reported for pyridine coordinated to high-spin nickel(II)
21-thiaporphyrin.61,62 In fact, the coordination equilibria of
pyridine by nickel(II) thiaethyneporphyrin are quite complex.
The selected and simplest example allows one to make quite a
fundamental point. Namely, thiaethyneporphyrin is capable of
accommodating both low- and high-spin nickel(II) cations, adjusting
appropriately the size of a coordination crevice. The created
coordination center provides a suitable environment, allowing
stabilization of the organonickel(II) complex and revealing an
unprecedented η2-CC coordination of high-spin nickel(II).10,63−67
Molecular Structures of 7-Pd and 7-Ni. The geometry of
7-Pd as determined by X-ray crystallography (Figure 8) reflects
range.82,83 Thus, the palladium(II) ion interacts with thiaethyne-
porphyrin in an η2-fashion engaging the C1 and C2 carbon atoms.
For comparison, the palladium(0) complexes containing alkenes
and/or alkynes built in the macrocyclic structure afforded the
formation of palladium(0)−η2-alkene [2.185(3)−2.197(4) Å] or
palladium(0)−η2-alkyne [2.107(4)−2.140(6) Å] bonds.84 A weak
interaction has been observed for palladium(II) p-benziporphyrin
and palladium(II) naphthiporphyrin complexes both in solution
and in the solid state; albeit, in these cases, the CC fragment built-
in arene units are involved.48,69
The C18−C1−C2−C3 butyne moiety is slightly bent toward
palladium(II), as is clearly reflected by the appropriate bond
angles [C18−C1−C2, 175.7(3)°; C1−C2−C3, 178.5(3)°].
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.63 The
dihedral angle between the thiophene plane and the Pd−N19−
N21−C1−C2 plane is 24.2°. This bending opens up the center
of the porphyrin to accommodate palladium(II) and allows
palladium(II) to interact with the thiophene sulfur in a side-on
fashion. The angle between the center of thiophene and the
Pd−S20 bond is 132.5°. Similar angles are found in palladium
21-thiaporphyrin.68 The Pd−S20 distance, 2.177(1) Å, is clearly
a bonding distance. Thus, the thiophene is σ-bonded to
palladium through sulfur, which has pyramidal geometry.
7-Ni reveals structural features similar to those of 7-Pd (Figure 9).
Some differences result from constraints imposed by smaller
Figure 8. Molecular structure of 7-Pd (top, perspective view; bottom,
side view with aryl groups omitted for clarity). The thermal ellipsoids
represent 50% probability. Selected bond distances: Pd−N19,
2.029(2) Å; Pd−N21, 2.026(2) Å; Pd−S20, 2.177(1) Å; Pd−C1,
2.289(3) Å; Pd−C2, 2.315(3) Å. The bond lengths in the
2
2
Csp CspCspCsp (C18−C1−C2-C3) unit are 1.386(4), 1.257(4), and
1.388(4) Å. The bottom view presents the geometry of the side-on
interaction between palladium(II) and thiophene.
the balance among constraints of the macrocycle ligand, the
size of the palladium(II) ion, and the predisposition of the
palladium(II) ion for square-planar geometry, resembling
eventually the structure of palladium(II) vacataporphyrin,
palladium(II) p-benziporphyrin,33,57,60,62 and palladium
21-thiaporphyrin.68,69
The most notable feature of 7-Pd is the nature of the Pd···C1,
Pd···C2, and Pd−S20 interactions. The bond-length pattern of
aromatic 7 is preserved in 7-Pd. In particular, the acetylene unit
approaches palladium(II) at distances much shorter [Pd···C1,
2.289(3) Å; Pd···C2, 2.315(3) Å] than the expected van der Waals
contact (Pd···C, 3.3 Å)70 but in the 2.110(7)−2.479(6) Å range
limits of the typical values for palladium(II)-η2-alkene com-
plexes.71−81 The relevant palladium(II)−η2-CC bond distances for
palladium(II)-η2-alkyne vary in the 2.245(14)−2.487(15) Å
Figure 9. Molecular structure of 7-Ni (top, perspective view; bottom,
side view with aryl groups omitted for clarity). The thermal ellipsoids
represent 50% probability. Selected bond distances: Ni−N19, 1.964(4)
Å; Ni−N21, 1.956(4) Å; Ni−S20, 2.087(1) Å; Ni−C1, 2.213(5) Å;
Ni−C2, 2.229(5) Å. The bond lengths in the Csp CspCspCsp (C18−
C1−C2−C3) unit are 1.345(6), 1.238(5), and 1.362(6) Å. The
bottom view presents the geometry of the interaction between
nickel(II) and thiophene.
2
2
cationic radii of low-spin nickel(II), which are expected and clearly
demonstrated by shorter Ni−N and Ni−S bond distances. Thus,
the nickel(II) ion interacts with thiaethyneporphyrin in a
η2-fashion, engaging the C1 and C2 carbon atoms. The C18−
C1−C2−C3 butyne moiety of 7-Ni is bent toward nickel(II)
stronger than for 7-Pd, as is clearly reflected by the appropriate
3253
dx.doi.org/10.1021/ic2027175 | Inorg. Chem. 2012, 51, 3247−3260

Inorganic Chemistry
Article
bond angles [C18−C1−C2, 173.5(7)°; C1−C2−C3, 174.5(7)°].
The C1C2 unit approaches nickel(II) at distances much shorter
[Ni···C1, 2.213(5) Å; Ni···C2, 2.229(5) Å] than the expected van
der Waals contact (Ni···C, 3.4 Å)70 but in the upper limit of
nickel(II)−η2-alkene bond lengths, which vary in the wide range
1.950(3)−2.285(7) Å.85−89 For comparison, the representative
nickel(0)−η2-CC bond distances are also given: nickel(0)−η2-
alkene [2.024(6) Å],90 nickel(0)−η2-benzene [2.021(1) Å],91
nickel(0)−η2-allene [1.916(5) Å],92 and nickel(0)−η2-alkyne
[1.875(4) Å].93,94 The relevant weak interaction has been
observed for the high-spin nickel(II) p-benziporphyrin complex
both in solution and in the solid state [Ni···C, 2.583(4) Å].47 In
fact, paramagnetic organonickel compounds are extremely
rare.10,63,64 The few examples include species with a σ-bound
methyl group [Ni(I)−C distance of 2.04(1) Å]65,66 or a η5-
cyclopentadienyl group (mean distance of 2.27 Å),66 and the
iodonickel(II) complex of 2,21-dimethylated N-confused porphyr-
in [2.404(9) Å].67
The dihedral angle between the thiophene plane and the
Ni−N19−N21−C1−C2 plane is 20.1°. Nickel(II) interacts
with the thiophene sulfur in a side-on fashion. The angle
between the center of the thiophene and the Ni−S20 bond
is 136°. Similar angles are found in the nickel(II)
21-thiaporphyrins.95,96
Density Functional Theory (DFT) Studies: Ethynepor-
phyrins. The magnetic manifestations of aromaticity and
antiaromaticity of 7 and its two-electron-oxidized derivative can
easily be observed using 1H NMR spectroscopy. However, this
method does not provide detailed information on the structural
consequences of electron delocalization in these two species.
Furthermore, in the absence of X-ray structural data, it is
difficult to ascertain whether [13-H2]2+ does exhibit bond
alternation along the [16]annulene pathway, expected for a 4n
π-electron system. To address these issues, we carried out DFT
calculations of 7 and [13-H2]2+, performing full geometry
optimizations at the B3LYP/6-31G** level. A genuine energy
minimum was obtained for 7 and [13-H2]2+.
The DFT-optimized geometry of 7 closely resembles that
determined by X-ray crystallography, revealing an equalization of
the C−C bond along the π delocalization route (Figure 10). The
DFT structure of [13-H2]2+ shows bond localization, as expected
of an antiaromatic planar [4n]annulenoid system. In fact, the
known structures of 16 π-electron porphyrin rings demonstrated
the presence of bond alternation characteristic of antiaromatic
structures in contrast to aromatic 18 π-electron porphyrins.97−102
To address the issue of macrocyclic conjugation on the built-in
acetylenic moiety, Wiberg bond indices have been applied to
estimate bond orders of C18−C1, C1−C2, and C2−C3 bonds in
thiaethyneporphyrin 7 and related compounds ([13-H2]2+,
7-Pd, 7-Ni; Table 1).103 In comparison to 11, applied here as a
suitable acetylene-like reference, the indices of C1−C2 in 7,
[13-H2]2+, 7-Pd, and 7-Ni approach values that are expected for
the double bond. At the same time, the indices for C18−C1 and
C2−C3 bonds approach the limit for the aromatic bond. Thus,
Wiberg bond indices reflect the essential role of cumulene
contributor 7-2 in the description of 20-thiaethyneporphyrin.
Nucleus-independent chemical shifts (NICS) have been
proposed by Schleyer et al. as a computational measure of
aromaticity that is related to experimental magnetic criteria.104,105
A NICS is defined as the negative shielding value computed at the
center of a ring. The NICS method has been used to assess the
aromaticity of annulenes or porphyrins106,107 and their ana-
logues.108−111 NICS values were calculated for 7 and [13-H2]2+
Figure 10. Calculated geometries and bond lengths (in Å) of
structures 7 (A), [13-H2]2+ (B), and 14-Pd (C). Nitrogen and sulfur
are shown in blue and yellow, respectively. Outer hydrogen atoms and
meso substituents are omitted for clarity. 7 and [13-H2]2+ have
effective Cs symmetry, and the equivalent bond distances are equal
within the given accuracy.
Table 1. Wiberg Bond Indices
bond
compound
C18−C1
C1−C2
C2−C3
a
b
c
11
1.011
2.8475
1.011
7
1.4475
1.5692
1.4201
1.3681
2.2621
2.1467
2.0097
2.1604
1.4475
1.5792
1.4201
1.3681
[13-H2]2+
7-Pd
7-Ni
a
b
c
C1−C2. C2−C3. C3−C4.
using the GIAO method at the optimization level for the central
15-membered ring. A comparison of the center ring NICS
(calculated for B3LYP/6-31G** geometries) values shows that
they are good indicators of macrocyclic aromaticity. For the
Huckel aromatic system 7, the central NICS value is negative
̈
(−13.05 ppm) and comparable with that reported for a porphyrin
(−16.5 ppm).106 For the antiaromatic structure of [13-H2]2+, the
3254
dx.doi.org/10.1021/ic2027175 | Inorg. Chem. 2012, 51, 3247−3260

Inorganic Chemistry
Article
center ring NICS is positive (+18.95 ppm). This value is larger
than the NICS obtained for [20]annulene (+12.1 ppm).112
Figure 11. Linear correlation between calculated and experimental
values of chemical shifts for (A) 7 and (B) [13-H2]2+ (orange,
thiophene; blue, pyrrole; pink, NH; green, aryl; red, methyl).
1H NMR chemical shifts have been calculated using the
GIAO−B3LYP method for the optimized (at the B3LYP/6-31G**
level) geometries of aromatic 7 and antiaromatic [13-H2]2+
(Figure 11). In the described cases, we have been in a unique
position to compare the experimental and calculated
chemical shifts assigned to aromatic and antiaromatic struc-
tures confined in the frame of ethyneporphyrin geometries.
We have concluded that there is a satisfactory qualitative agree-
ment for each considered set of theoretical and experimental data
readily demonstrated by linear correlations between the calcu-
lated and experimental chemical shifts (Figure 11).
Figure 12. Geometries of 7-Pd (A) and 14-Pd (B) obtained in a DFT
study. Projections emphasize the conformations of the macrocycles.
Outer hydrogen atoms and meso substituents (bottom views) are
omitted for clarity.
DFT Calculations: Metalloporphyrinoids. The principal
geometries of 7-Ni, 7-Pd, and 14-Pd were subjected to a DFT
optimization at the B3LYP level of theory with the LANL2D
basis set for palladium complexes and the 6-31G** basis set for
nickel complexes. The final geometries are shown in Figure 12
and S9 in the Supporting Information. In each case, a genuine
energy minimum was obtained. Significantly, the DFT-
optimized structural parameters of 7-Pd and 7-Ni are essentially
similar to those determined by X-ray crystallography, which
adds credibility to the geometry of the DFT-optimized
structure of 14-Pd. 1H NMR chemical shifts have been
calculated using the GIAO−B3LYP method for the optimized
geometries of 7-Pd, 7-Ni, and 14-Pd. Linear correlations
between the calculated and experimental values of the chemical
shifts for each complex have been determined (Figures S10−
S12 in the Supporting Information).
palladium(II)···η2-C1C2 and nickel(II)···η2-C1C2 interaction
in 7-Pd and 7-Ni. The data gathered in Table 2 provide examples
Table 2. Wiberg Bond Indices
compound
bond
7-Pd
7-Ni
M−C1
M−C2
M−N19
M−N21
M−S20
0.1649
0.1650
0.4700
0.4700
0.6329
0.1589
0.1589
0.3888
0.3888
0.5514
of the typical coordination bonds M−N and M−S and the
metal(II)···η2-C1C2 itself. Evidently, the metal(II)···C1 and
metal(II)···C2 interactions have significant bonding character,
albeit smaller than simultaneously coordinating nitrogen atoms.
The interaction involving metal(II) and the ethyne frag-
ment in 7-M is of special interest. A comparison of the pro-
perties of Wiberg bond indices is helpful in discussing the
3255
dx.doi.org/10.1021/ic2027175 | Inorg. Chem. 2012, 51, 3247−3260

Inorganic Chemistry
Article
1
yield (white crystals, 4.43 g). H NMR (600 MHz, CD2Cl2, 300 K): δ
7 . 5 4 ( 4 H , o - P h ) , 7 . 3 9 ( 4 H , m - P h ) , 7 . 3 4 ( 2 H ,
p-Ph), 5.55 (2H, H1, H4), 2.43 (2H, OH). 13C NMR (150.90 MHz,
CD2Cl2, 300 K): δ 142.2, 130.2, 130.0, 128.1, 87.9, 66.0. HR-MS (ESI,
m/z): 221.0992 (221.0966 calcd for [C16H14O2 − OH]+).
CONCLUSION
■
Thiaethyneporphyrin is an aromatic porphyrinoid that presents
the essential features of [18]triphyrin(4.1.1). The combination
of two structural motifs of 21-thiaporphyrin and ethyne in
thiaethyneporphyrin provided a unique opportunity to study
metal(II)···η2-C1C2 interactions. In this contribution, we have
demonstrated that 20-thiaethyneporphyrin acts as a macrocyclic
ligand to palladium(II) or nickel(II), which are suitably held via
two pyrrolic nitrogen and one thiophenic sulfur atoms in the
T-like fashion, being conveniently exposed to interaction with a
conjugated four-carbon linker of porphyrinoid. Eventually, two
fundamental patterns of interactions between metal(II) and a
four-carbon conjugated moiety have been recognized. The first
one corresponds to a regular η2-type bond and involves the
C1C2 fragment. Significantly, the CC unit is located in the
plane defined by the remaining three donor atoms. The second
mode was revealed once palladium(II) thiaethyneporphyrin
reacted with sodium borohydride, yielding palladium(II)
thiaetheneporphyrin. The profound structural changes due to
the addition of hydride and palladium(II) to the C1C2 unit
allowed one to create the regular Pd−C σ bond, demonstrating
that [18]thiatriphyrins(4.1.1) can act as “true” carbaporphy-
rinoids. It is significant to emphasize that the coordination core
of [18]thiatriphyrins(4.1.1) is quite flexible, accommodating
peculiar organometallic compounds represented in this work
by high-spin nickel(II) organometallic species. In terms of the
characterization of intermediates involved in selective C−C bond
activation by metals under mild conditions, the reported organo-
metallic compounds provide suitable structural models of the
transient species. Previously reported [18]triphyrins(6.1.1)
(vacataporphyrin) applied as a ligand toward metal(II) demon-
strated the peculiar plasticity of its molecular and electronic
structure.33,34,64,113,114 The present contribution revealed that the
length of the meso bridge allows one to control the electronic
structure and coordination properties of this class of porphyr-
inoids. Generally, [N]triphyrins(n.1.1) provide a stimulating
environment to explore the specific issues of organometallic
chemistry, applying the macrocyclic platform concept as the
suitable approach.
Dicobalt Complex of 1,4-Diphenyl-2-butyne-1,4-diol (9).
Dicobalt octacarbonyl (4.31 g, 12.6 mmol) was added to a solution
of 8 (3.0 g, 12.6 mmol) in THF (150 mL). The mixture was stirred in
a nitrogen atmosphere for 24 h. Then the solvent was evaporated to
dryness, and the residue was purified by chromatography on silica gel.
The main red fraction eluted with dichloromethane was collected to
1
give 9 with 95% yield (6.61 g). H NMR (500 MHz, CDCl3, 298 K):
two stereoisomers were observed, δ 7.5−7.3 (1,4-o, m, p), 5.96 (H1,
H4), 5.80 (H1, H4), 3.40 (OH), 3.30 (OH). 13C NMR (125.7 MHz,
CDCl3, 300 K): δ 198.4, 143.6, 143.2, 128.7, 128.5, 128.3, 128.2,
125.7, 125.6, 75.1, 74.6.
Dicobalt Complex of 1,4-Diphenyl-1,4-di(pyrrol-2-yl)but-2-
yne (10). Compound 9 (1.64 g, 3.14 mmol) was dissolved in dry
pyrrole (8.69 mL), and the solution was purged with nitrogen gas for
10 min. Then trifluoroacetic acid (TFA; 1.2 mL, 15.7 mmol) was
added, and the mixture was stirred in a nitrogen atmosphere for 2 h.
Next 50 mL of freshly distilled dichloromethane was added, and the
solution was neutralized by the addition of a 40% solution of sodium
hydroxide (30 mL). The organic layer was washed with water (3 ×
40 mL) and dried (anhydrous MgSO4), and the solvent was
evaporated to dryness. The residue was purified by chromatography
on silica gel. The main brown-red fraction eluted with a dichloro-
methane/hexane fraction (1:2, v/v) was collected to give 10 with 60%
1
yield (brown-red oil, 1.17 g). H NMR (500 MHz, CDCl3, 298 K):
two stereoisomers were observed, δ 7.85, 7.74, 7.43−7.29, 6.60, 6.57,
6.14, 6.12, 5.37, 5.34. 13C NMR (CDCl3, 298 K): δ 198.8, 142.7, 142.6,
132.3, 132.0, 128.9, 128.8, 128.4, 127.7, 127.6, 118.2, 117.6, 108.4,
108.3, 107.7, 107.5, 103.0, 102.7, 49.8, 49.3.
1,4-Diphenyl-1,4-di(pyrrol-2-yl)but-2-yne (11). Compound 10
(0.2 g, 0.32 mmol) was dissolved in ethanol (6.7 mL); then
Fe(NO3)3·9H2O (0.52 g, 1.28 mmol) was added, and the mixture
was stirred for 20 min. Subsequently, the mixture was combined with
water (15 mL) and extracted with diethyl ether (3 × 20 mL). The
organic layer was dried (anhydrous MgSO4), and the solvent was
evaporated to dryness. The residue was purified by chromatography on
silica gel. A second yellow fraction eluted with dichloromethane/
n-hexane (1:1, v/v) was collected to give 11 with 30% yield (yellow oil,
32 mg). 1H NMR (600 MHz, CD2Cl2, 300 K): δ 8.16 (2H, NH), 7.43
(4H, o-Ph), 7.36 (4H, m-Ph), 7.29 (2H, p-Ph), 6.67 (2H, pyr), 6.11
(2H, pyr), 6.02 (2H, pyr), 5.20 (2H, H1, H4). 13C NMR (150.90
MHz, CD2Cl2, 300 K): δ 142.2 (i-Ph), 132.4 (α-pyr), 130.3 (m-Ph),
129.1 (o-Ph), 128.8 (p-Ph), 118.9 (pyr), 110.1 (pyr), 107.8 (pyr), 84.9
(C2, C3), 38.4 (C1, C4). HR-MS (ESI, m/z): 337.1755 (337.1705
calcd for [C24H20N2 + H]+).
EXPERIMENTAL SECTION
■
Materials. 2,5-Bis(p-tolylhydroxymethyl)thiophene was prepared
via a previously reported procedure by Ulman and Manassen.115
Solvents like methanol, ethanol, and n-hexane, at least pure grade, were
used without purification. Tetrahydrofuran (THF), toluene and N,N-
dimethylformamide (DMF) were purified via pushing through
absorber column (M Braun SPS-800 system). Dichloromethane and
triethylamine were distilled over CaH2. Dichloromethane-d2 was used
as received. Chloroform-d was prepared directly before use by passing
through a basic alumina column. Inorganic salts were used without
purification.
1,4-Diphenyl-2-butyne-1,4-diol (8) was prepared via a modified
procedure reported by Krupowicz and Sapiecha.36,37 THF (200 mL),
ethylmagnesium bromide (40 mL, 1 M in THF, 0.04 mol), and
ethynylmagnesium bromide (80 mL, 0.5 M in THF, 0.04 mol) were
placed in a 500-mL round-bottomed flask. The mixture was stirred
under a nitrogen atmosphere for 16−18 h. Then the reaction mixture
was heated until reflux, and a solution of benzaldehyde (0.08 mol) in
THF (20 mL) was added dropwise over a period of 20 min, after which
reflux was maintained for 7 h. The mixture was cooled to room
temperature and stirred overnight. The reaction mixture was quenched
with water (100 mL) and extracted with diethyl eter (3 × 50 mL). The
combined organic phases were dried (anhydrous MgSO4) and evaporated
to dryness on a rotary evaporator to give a yellow-brown oil.
Recrystallization from dichloromethane/n-hexane produced 8 with 47%
3,18-Diphenyl-8,13-di-p-tolyl-20-thiaethyneporphyrin (7).
Compound 11 (314 mg, 0.935 mmol) and 2,5-bis-
(tolylhydroxymethyl)thiophene (303 mg, 0.935 mmol) were dissolved
in freshly distilled dichloromethane (312 mL) in a 500-mL round-
bottomed flask equipped with stirring bar and a nitrogen inlet.
Nitrogen was bubbled through the solution for 15 min; then boron
trifluoride−diethyl ether (117 μL, 0.935 mmol) was added, and the
mixture was stirred in the dark for 15 min under a nitrogen
atmosphere. Triethylamine (130 μL, 0.935 mmol) and 2,3-dichloro-
5,6-dicyano-p-benzoquinone (DDQ; 424 mg, 1.87 mmol) were added,
and the solution was stirred for a further 30 min. Then the solvent was
evaporated to dryness, and the residue was purified by chromatog-
raphy on basic allumine (II°). The main orange fraction eluted with
dichloromethane was collected and recrystallized from dichloro-
methane/methanol to give 7 with 33% yield (191 mg). UV−vis
[λmax, nm (log ε, M−1 cm−1)]: 439 (5.1), 508 (4.2), 539 (3.9), 630
(3.3), 710 (3.1). HR-MS (ESI, m/z): 620.2290 (620.2286 calcd for
[C44H32N2S]•+). H NMR (600 MHz, CDCl3, 300 K): δ 9.16 (s, 2H,
1
H10, H11), 8.97 (dd, 3J = 4.4 Hz, 4J = 2.2 Hz, 2H, H5, H16), 8.84 (d,
3J = 7.6 Hz, 4H, 3,18-o), 8.75 (dd, J = 4.4 Hz, J = 2.2 Hz, 2H,
3
4
3
3
H6, H15), 8.27 (d, J = 7.8 Hz, 4H, 8,13-o), 7.84 (t, J = 7.6 Hz, 4H,
3256
dx.doi.org/10.1021/ic2027175 | Inorg. Chem. 2012, 51, 3247−3260

Inorganic Chemistry
Article
3
3
3
3
3,18-m), 7.65 (d, J = 7.8 Hz, 4H, 8,13-m), 7.60 (t, J = 7.3 Hz, 2H,
3,18-p), 2.68 (s, 6H, CH3), −3.29 (bs, 2H, H19, H21). 13C NMR
(150.90 MHz, CDCl3, 300 K): δ 140.4 (3,18-ipso), 137.7 (8,13-p),
137.5 (8,13-ipso), 136.2 (9,12), 134.3 (8,13-o), 133.9 (7,14), 132.7
(3,18-o), 132.3 (4,17), 129.5 (10,11), 129.2 (3,8,13,18-m), 126.9
(3,18-p), 122.6 (6,15), 117.9 (1,2), 117.5 (5,16), 116.8 (8,13), 102.3
(3,18), 21.5 (Me).
(bs, 2H, 8,13-o), 8.41 (d, J = 4.5 Hz, H6, H15), 7.81 (t, J = 7.6 Hz,
3
4H, 3,18-m), 7.69 (bs, 2H, 8,13-o), 7.60 (t, J = 7.6 Hz, 2H, 3,18-p),
7.56 (bs, 2H, 8,13-m), 7.53 (bs, 2H, 8,13-m), 2.65 (s, 6H, Me). H
1
NMR (600 MHz, CDCl3, 282 K): δ 9.04 (s, 2H, H10, H11), 8.74 (d,
3J = 4.6 Hz, 2H, H5, H16), 8.64 (d, 3J = 7.8 Hz, 4H, 3,18-o), 8.62 (d,
3J = 7.7 Hz, 2H, 8,13-o), 8.44 (d, J = 4.6 Hz, H6, H15), 7.79 (t, J =
3
3
3
7.8 Hz, 4H, 3,18-m), 7.67 (d, J = 7.5 Hz, 2H, 8,13-m′), 7.60 (d, 2H,
3
3
Dehydro-3,18-diphenyl-8,13-di-p-tolyl-20-thiaethynepor-
phyrin Dication ([13-H22+]). The solution of 7 in CDCl3 or CD2Cl2
was placed in an NMR tube (typically, a sample of ∼1−2 mg of 16).
Then excess of DDQ in the presence of HBF4 etherate was added, and
a change of color from orange to brown-red was observed. The
oxidation of 7 afforded a 1H NMR spectrum readily assigned to [13-H2]2+.
HR-MS (ESI, m/z): 619.2206 (619.2208 calcd for [C44H30N2S +
8,13-o′), 7.58 (t, J = 7.4 Hz, 2H, 3,18-p), 7.51 (d, J = 7.5 Hz, 2H,
8,13-m), 2.64 (s, 6H, Me). 13C NMR (150.90 MHz, CDCl3, 300 K): δ
159.5 (α-pyr), 143.1 (α-pyr), 140.0 (8,13-p), 139.7 (8,13-ipso), 139.4
(3,18-ipso), 136.6 (8,13-o), 133.4 (3,18-o), 131.0 (3,18-m), 130.9
(10,11), 130.7 (8,13-m), 129.0 (3,18-p), 128.0 (9,12), 125.7 (8,13),
124.5 (5,16), 124.2 (6,15), 115.8 (1,2), 107.2 (3,18), 22.8 (Me).
Palladium(II) Complex of 3,18-Diphenyl-8,13-di-p-tolyl-20-
thiaetheneporphyrin (14-Pd). The solution of 7-Pd in CD2Cl2 was
placed in an NMR tube (typically, a sample of ∼1−2 mg of 7-Pd).
Then the ethanol solution of NaBH4 was added gradually (at 30 min
intervals) through a 25 μL microsyringe. The addition of a reducting
agent was stopped when the entire amount of 7-Pd was converted to
14-Pd. HR-MS (ESI, m/z): 725.1265 (725.1248 calcd for
H]+). H NMR (600 MHz, CDCl3, 300 K): δ 25.35 (s, 2H, H19,
1
H21), 7.25 (t, 3J = 7.5 Hz, 2H, 3,18-p), 7.10 (t, 3J = 7.9 Hz, 4H, 3,18-
m), 7.06 (d, 3J = 8.1 Hz, 4H, 8,13-m), 6.96 (s, 2H, H10, H11), 6.80 (d,
3J = 8.3 Hz, 4H, 8,13-o), 6.60 (d, J = 7.9 Hz, 4H, 3,18-o), 6.08 (dd,
3
3J = 5.0 Hz, 4J = 1.9 Hz, 2H, H5, H16), 5.96 (dd, 3J = 5.0 Hz, 4J = 1.9
Hz, 2H, H6, H15), 2.34 (s, 6H, Me).
[C44H31N2S106Pd]−). H NMR (600 MHz, CD2Cl2, 180 K): δ 8.76
1
iso-Thiaethyneporphyrin (12′-H+). The solution of 7 in CD2Cl2
was placed in an NMR tube (typically, a sample of ∼1−2 mg of 7).
The titration of 7 was carried out with HBF4 etherate or TFA at 298 K.
3
3
(s, 1H, H2), 8.62 (d, 1H, J = 7.8 Hz, 8-o), 8.56 (d, J = 7.8 Hz, 1H,
13-o), 8.24 (d, 3J = 7.3 Hz, 1H, 18-o′), 8.17 (d, 3J = 5.3 Hz, 1H, H11),
8.15 (d, 3J = 7.3 Hz, 1H, 18-o), 8.06 (d, 3J = 7.5 Hz, 1H, 3-o′), 8.05 (d,
3J = 5.3 Hz, 1H, H10), 7.89 (d, 3J = 3.8 Hz, 1H, H5), 7.85 (d, 3J = 7.3
Hz, 3-o), 7.84 (d, 3J = 3.8 Hz, 1H, H6), 7.81 (d, 3J = 3.8 Hz, 1H, H15),
1
The progress of the reaction was followed by NMR spectroscopy. H
NMR (600 MHz, CD2Cl2, 300 K): δ 9.65, 9.50, 8.06, 7.81, 7.70, 7.59−
7.55, 7.54, 7.52, 7.46, 7.44, 7.32, 7.27, 7.24, 7.23, 7.12, 6.35, 5.50, 2.52,
2.39.
3
3
7.77 (d, J = 3.6 Hz, 1H, H16), 7.66 (t, J = 7.3 Hz, 1H, 18-m′), 7.59
3
3
(t, J = 7.3 Hz, 1H, 18-m), 7.57 (t, J = 7.1 Hz, 1H, 3-m′), 7.55
(d, 1H + 1H, 8,13-m), 7.44 (t, 3J = 7.4 Hz, 1H, 3-m), 7.40 (t, 3J = 7.4
Hz, 1H, 18-p), 7.39 (t, 1H, 3-p), 7.37 (d, 3J = 7.8 Hz, 1H, 13-o′), 7.33
(d, 3J = 7.8 Hz, 1H, 13-m′), 7.21 (d, 3J = 7.8 Hz, 1H, 8-m′), 7.03 (d, 3
J = 7.8 Hz, 1H, 8-o′), 2.49 (s, 3H, 13-Me), 2.47 (s, 3H, 8-Me). 13C
NMR (150.90 MHz, CDCl3, 300 K): δ 153.1, 150.8, 148.1, 140.7,
140.0, 139.7, 139.6, 137.4, 137.2, 137.1, 136.3, 135.8−135.7, 135.2,
134.3, 133.9, 133.7, 133.5, 132.7, 132.5, 132.1, 130.8, 130.6, 129.5,
129.3−129.2, 129.1, 129.0, 128.8, 128.4, 128.1, 127.7, 127.6, 127.1,
126.1−125.9, 122.1, 122.0 (C2), 119.2, 118.1, 115.9, 22.0.
Nickel(II) Complex of 3,18-Diphenyl-8,13-di-p-tolyl-20-
thiaethyneporphyrin (7-Ni). Nickel(II) acetate (28 mg, 0.1
mmol) in 5 mL of DMF was added to a dark-orange toluene solution
of 7 (7 mg, 0.01 mmol). The mixture was refluxed under nitrogen. The
progress of the reaction was followed by UV−vis spectroscopy. After
the disappearance of absorption peaks ascribed to the starting material
(it usually takes ∼5 h), the solvent was evaporated to dryness and the
residue was purified by chromatography on silica gel. The main brown-
red fraction eluted with dichloromethane was collected and recrystal-
lized from dichloromethane/n-hexane to give 7-Ni with 50% yield.
UV−vis [λmax, nm (log ε, M−1 cm−1)]: 291.0 (4.4), 435.0 (4.6), 595.0
(3.7). HR-MS (ESI, m/z): 676.1483 (676.1483 calcd for
Instrumentation. NMR spectra were measured on Bruker Avance
1
500 MHz and Bruker Avance 600 MHz spectrometers. H and 13C
1
[C44H30N2SNi]•+). H NMR (500 MHz, CD2Cl2, 300 K): δ 8.97 (s,
NMR shifts were referenced to the residual resonances of deuterated
solvents. Two-dimensional NMR spectra were recorded typically with
2048 data points in the t2 domain and up to 1024 points in the t1
domain, with a 1 s recovery delay. Absorption spectra were recorded
on a Varian Carry-50 Bio spectrophotometer. Mass spectra (high
3
3
2H, H10, H11), 8.44 (d, J = 4.5 Hz, 2H, H5, H16), 8.43 (d, J = 7.6
3
Hz, 4H, 3,18-o), 8.22 (d, J = 4.5 Hz, 2H, H6, H15), 7.94 (bs, 4H,
3
3
8,13-o), 7.72 (t, J = 7.6 Hz, 4H, 3,18-m), 7.55 (t, J = 7.6 Hz, 2H,
3,18-p), 7.54 (d, 3J = 8.0 Hz, 4H, 8,13-m), 2.59 (s, 6H, Me). 13C NMR
(150.90 MHz, CD2Cl2, 300 K): δ 160.9 (α-pyr), 145.9 (α-pyr), 140.0
(8,13-p), 139.5 (8,13-ipso), 138.7 (3,18-ipso), 133.9 (8,13-o), 132.6
(3,18-o), 130.8 (3,18-m), 130.7 (8,13-m), 129.7 (10,11), 128.9 (3,18-
p), 127.1 (9,12), 127.0 (6,15), 124.2 (8,13), 124.0 (5,16), 116.8 (1,2),
105.9 (3,18), 22.8 (Me).
resolution and accurate mass) were recorded on a Bruker micro-TOF-
̈
Q spectrometer using the electrospray technique. X-ray-quality crystals
of 7 and 7-Pd were prepared by the diffusion of methanol or n-hexane
and o-dichlorobenzene, respectively, into a chloroform solution
contained in a tube stored in a refrigerator. X-ray-quality crystals of
7-Ni and 11 were prepared by the diffusion of n-hexane or n-heptane,
respectively, into a dichloromethane solution contained in a tube
stored at room temperature. Data were collected at 100 K for 7 and
7-Pd, 7-Ni and at 110 K for 11 on an Xcalibur PX-k geometry
diffractometer, with Mo Kα radiation (λ = 0.71073 Å). Data were
corrected for Lorentz and polarization effects. An analytical absorption
correction was applied for 7-Pd and 7-Ni. Crystal data are compiled in
Table S1 in the Supporting Information. Structures were solved by a
heavy metal (7-Pd) and direct (7, 7-Ni, and 11) methods with
SHELXS-97 and refined by a full-matrix least-squares method by
using SHELXL-97 with anisotropic thermal parameters for almost all
non-hydrogen atoms. Scattering factors were those incorporated into
SHELXS-97.116,117 Electrochemical measurements were performed
with an EA9C multifunctional electrochemical analyzer under the
following conditions: CH2Cl2; 0.1 M TBAP; scan rate, 50 mV s−1;
working electrode, glassy carbon disk; auxliary electrode, platinum
wire; reference electrode, Ag/AgCl. The voltammograms were
referenced against the half-wave potential of Fc/Fc+.
Dipyridinenickel(II) Complex of 3,18-Diphenyl-8,13-di-
p-tolyl-20-thiaethyneporphyrin (7-Ni-py). The solution of 7-Ni
in CD2Cl2 was placed in an NMR tube (typically, a sample of ∼1−2
mg of 7-Ni). Titration of 7-Ni with pyridine at 200 K afforded the 1H
NMR spectrum readily assigned to 7-Ni-py. 1H NMR (600 MHz,
CD2Cl2, 200 K): δ 117.0 (pyrr), 71.2 (H3), 54.9 (pyrr), 22.3 (H4),
−17.4 (th).
Palladium(II) Complex of 3,18-Diphenyl-8,13-di-p-tolyl-20-
thiaethyneporphyrin (7-Pd). Palladium(II) acetate (36 mg, 0.16
mmol) was added to a dark-orange toluene solution of 7 (10 mg, 0.016
mmol). The mixture was refluxed. The progress of the reaction was
followed by UV−vis spectroscopy. After the disappearance of
absorption peaks ascribed to the starting material (it usually takes
∼4 h), the solvent was evaporated to dryness and the residue was
purified by chromatography on silica gel. The main brown-red fraction
eluted with dichloromethane was collected and recrystallized from
CH2Cl2/CH3OH to give 7-Pd with 60% yield. UV−vis [λmax, nm (log
ε, M−1 cm−1)]: 285.5 (4.4), 373.0 (4.1), 462.0 (4.9), 578.5 (3.8). HR-
MS (ESI, m/z): 724.1175 (724.1180 calcd for [C44H30N2S106Pd]•+).
1H NMR (600 MHz, CD2Cl2, 300 K): δ 9.04 (s, 2H, H10, H11), 8.72
DFT Calculations. Geometry optimizations were carried out within
unconstrained C1 symmetry, with the starting coordinates derived from
molecular mechanic calculations.118 Becke’s three-parameter exchange
(d, 3J = 4.5 Hz, 2H, H5, H16), 8.64 (d, 3J = 7.6 Hz, 4H, 3,18-o), 8.61
3257
dx.doi.org/10.1021/ic2027175 | Inorg. Chem. 2012, 51, 3247−3260

Inorganic Chemistry
Article
functional with the gradient-corrected correlation formula of Lee, Yang,
and Parr (DFT-B3LYP) was used with the LANL2D basis set for Pd and
6-31G** for other atoms.119,120 Harmonic vibrational frequencies were
calculated using analytical second derivatives. The structure was found to
have converged to a minimum on the potential energy surface. The
resulting zero-point vibrational energies were included in the calculation
of the relative energies. Calculations of the NMR properties for the
investigated systems were performed for the optimized structures.
Analysis of Wiberg’s bond indices was performed for the final geometry
using NBO.3.0 software.121
(15) Inokuma, Y.; Kwon, J. H.; Ahn, T. K.; Yoo, M. C.; Kim, D.;
Osuka, A. Angew. Chem., Int. Ed. 2006, 45, 961−964.
(16) Inokuma, Y.; Yoon, Z. S.; Kim, D.; Osuka, A. J. Am. Chem. Soc.
2007, 129, 4747−4761.
(17) Takeuchi, Y.; Matsuda, A.; Kobayashi, N. J. Am. Chem. Soc.
2007, 129, 8271−8281.
́ ́
(18) Mysliborski, R.; Latos-Grazynski, L.; Szterenberg, L.; Lis, T.
̇
Angew. Chem., Int. Ed. 2006, 45, 3670−3674.
(19) Heremans, P.; Cheyns, D.; Rand, B. P. Acc. Chem. Res. 2009, 42,
1740−1747.
(20) Torres, T. Angew. Chem., Int. Ed. 2006, 45, 2834−2837.
(21) Claessens, C. G.; Gonzalez-Rodriguez, D.; Torres, T. Chem. Rev.
2002, 102, 835−853.
ASSOCIATED CONTENT
* Supporting Information
■
S
(22) Rodriguez, D.; Torres, T.; Guldi, D. M.; Rivera, J.; Herranz,
M. A.; Echegoyen, L. J. Am. Chem. Soc. 2004, 126, 6301−6313.
(23) Kobayashi, N. Synthesis and Spectroscopic Properties of
Phthalocyanine Analogs. In The Porphyrin Handbook; Kadish, K. M.,
Smith, K. M., Guilard, R., Eds.; Academic Press: San Diego, 2003; pp
161−162.
(24) Inokuma, Y.; Osuka, A. Dalton Trans. 2008, 2517−2526.
(25) Anju, K. S.; Ramakrishnan, S.; Srinivasan, A. Org. Lett. 2011, 13,
2498−2501.
Tables of computational results (Cartesian coordinates), figures
presenting correlations between calculated and experimental 1H
NMR chemical shifts, additional NMR data, cyclic voltammetry
data, and X-ray crystallographic data in CIF format. This
material is available free of charge via the Internet at http://
pubs.acs.org.
AUTHOR INFORMATION
Corresponding Author
■
(26) Xue, Z. L.; Mack, J.; Lu, H.; Zhang, L.; You, X. Z.; Kuzuhara, D.;
Stillman, M.; Yamada, H.; Yamauchi, S.; Kobayashi, N.; Shen, Z.
Chem.Eur. J. 2011, 17, 4396−4407.
*E-mail: lechoslaw.latos-grazynski@chem.uni.wroc.pl. Tel:
+48 71 3757256. Fax: +48 71 3282348. Homepage: http://
llg.chem.uni.wroc.pl.
(27) Kuzuhara, D.; Yamada, H.; Xue, Z. L.; Okujima, T.; Mori, S.;
Shen, Z.; Uno, H. Chem. Commun. 2011, 47, 722−724.
(28) Xue, Z. L.; Shen, Z.; Mack, J.; Kuzuhara, D.; Yamada, H.;
Okujima, T.; Ono, N.; You, X. Z.; Kobayashi, N. J. Am. Chem. Soc.
2008, 130, 16478.
Notes
The authors declare no competing financial interest.
(29) Badger, G. M.; Elix, J. A.; Lewis, G. E. Aust. J. Chem. 1965, 18,
ACKNOWLEDGMENTS
■
70−89.
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).
(30) Badger, G. M.; Elix, J. A.; Lewis, G. E. Aust. J. Chem. 1966, 19,
1220−1241.
(31) Badger, G. M.; Lewis, G. E.; Singh, U. P. Aust. J. Chem. 1967, 20,
1635−1642.
(32) Pacholska, E.; Latos-Grazyn
2002, 8, 5403−5406.
(33) Pacholska-Dudziak, E.; Skonieczny, J.; Pawlicki, M.;
ski, L.; Ciunik, Z. Chem.Eur. J.
̇
REFERENCES
■
Szterenberg, L.; Ciunik, Z.; Latos-Grazyn
2008, 130, 6182−6195.
(34) Pacholska-Dudziak, E.; Gaworek, A.; Latos-Grazyn
́
̇
(1) Jux, N.; Koch, P.; Schmickler, H.; Lex, J.; Vogel, E. Angew. Chem.,
Int. Ed. Engl. 1990, 29, 1385−1387.
́
(2) Martire, D. O.; Jux, N.; Aramendia, P. F.; Negri, R. M.; Lex, J.;
Chem. 2011, 50, 10956−10965.
Braslavsky, S. E.; Schaffner, K.; Vogel, E. J. Am. Chem. Soc. 1992, 114,
9969−9978.
(35) Pawlicki, M.; Latos-Grazyn
ski, L. Chem. Rec. 2006, 6, 64−78.
̇
(36) Krupowicz, J.; Sapiecha, K. Rocz. Chem. 1973, 47, 1729−1730.
(37) Krupowicz, J.; Sapiecha, K.; Gaszczyk, R. Rocz. Chem. 1974, 48,
2067−2068.
(38) Lockwood, R. F.; Nicholas, K. M. Tetrahedron Lett. 1977, 4163−
4166.
(3) Weghorn, S. J.; Lynch, V.; Sessler, J. L. Tetrahedron Lett. 1995, 36,
4713−4716.
(4) Kurata, H.; Baba, H.; Oda, M. Chem. Lett. 1997, 571−572.
(5) Mena-Osteritz, E.; Bauerle, P. Adv. Mater. 2001, 13, 243−246.
(6) Fuhrmann, G.; Debaerdemaeker, T.; Bauerle, P. Chem. Commun.
̈
(39) Padmanabhan, S.; Nicholas, K. M. Tetrahedron Lett. 1983, 24,
2003, 948−949.
2239−2242.
(7) Kromer, J.; Rios-Carreras, I.; Fuhrmann, G.; Musch, C.;
Wunderlin, M.; Debaerdemaeker, T.; Mena-Osteritz, E.; Bauerle, P.
Angew. Chem., Int. Ed. 2000, 39, 3481−3486.
(40) Schreiber, S. L.; Klimas, M. T.; Sammakia, T. J. Am. Chem. Soc.
1987, 109, 5749−5759.
(41) Nicholas, K. M. Acc. Chem. Res. 1987, 20, 207−214.
(42) Teobald, B. J. Tetrahedron 2002, 58, 4133−4170.
(43) Omae, I. Appl. Organomet. Chem. 2007, 21, 318−344.
(44) Bromfield, K. M.; Graden, H.; Ljungdahl, N.; Kann, N. Dalton
Trans. 2009, 5051−5061.
(8) Vogel, E.; Jux, N.; Dorr, J.; Pelster, T.; Berg, T.; Bohm, H. S.;
Behrens, F.; Lex, J.; Bremm, D.; Hohlneicher, G. Angew. Chem., Int. Ed.
2000, 39, 1101−1105.
́
(9) Berlicka, A.; Latos-Grazynski, L. Wiad. Chem. 2008, 61, 339−369.
̇
(10) Pawlicki, M.; Latos-Grazyn
́
ski, L. Carbaporphyrinoids
̇
(45) Lash, T. D. Eur. J. Org. Chem. 2007, 5461−5481.
Synthesis and Coordination Properties. In Handbook of Porphyrin
Science: with Applications to Chemistry, Physics, Materials Science,
Engineering, Biology and Medicine; Kadish, K. M., Smith, K. M., Guilard,
R., Eds.; World Scientific Publishing: Singapore, 2010; pp 104−192.
(46) Stepien
́
́
̇
̨
3838−3839.
(47) Stepien
̨
Latajka, Z. J. Am. Chem. Soc. 2004, 126, 4566−4580.
(11) Berlicka, A.; Latos-Grazyn
2005, 44, 5288−5291.
(12) Berlicka, A.; Sprutta, N.; Latos-Grazyn
ski, L.; Lis, T. Angew. Chem., Int. Ed.
̇
(48) Szyszko, B.; Latos-Grazyn
4354−4363.
ski, L. Chem. Commun.
̇
(49) Stepien
, M.; Szyszko, B.; Latos-Grazyn
2006, 3346−3348.
̨
3930−3933.
(13) Meller, A.; Ossko, A. Monatsh. Chem. 1972, 103, 150−155.
(14) Rodriguez-Morgade, M. S.; Esperanza, S.; Torres, T.; Barbera, J.
Chem.Eur. J. 2004, 11, 354−360.
(50) Hung, C. H.; Lin, C. Y.; Lin, P. Y.; Chen, Y. J. Tetrahedron Lett.
2004, 45, 129−132.
3258
dx.doi.org/10.1021/ic2027175 | Inorg. Chem. 2012, 51, 3247−3260

Inorganic Chemistry
Article
(51) Latos-Grazyn
́
(83) Ara, I.; Falvello, L. R.; Fernandez, S.; Fornies, J.; Lalinde, E.;
Martin, A.; Moreno, M. T. Organometallics 1997, 16, 5923−5937.
(84) Pla-Quintana, A.; Torrent, A.; Dachs, A.; Roglans, A.; Pleixats,
R.; Moreno-Manas, M.; Parella, T.; Benet-Buchholz, J. Organometallics
2006, 25, 5612−5620.
̇
J. Am. Chem. Soc. 1987, 109, 4428−4429.
(52) Kawase, T.; Muro, S.; Kurata, H.; Oda, M. J. Chem. Soc., Chem.
Commun. 1992, 778−779.
(53) Vandonge, J. P.; Debie, M. J. A.; Steur, R. Tetrahedron Lett.
1973, 1371−1374.
(85) Battiste, M. A.; Griggs, B. G.; Sackett, D.; Coxon, J. M.; Steel,
P. J. J. Organomet. Chem. 1987, 330, 437−446.
(54) Nakagawa, M. Angew. Chem., Int. Ed. Engl. 1979, 18, 202−214.
́ ́
(55) Stepien, M.; Latos-Grazynski, L. Aromaticity and tautomerism
̇
̨
(86) Churchil, M. R.; Deboer, B. G.; Hackbart, J. J. Inorg. Chem.
1974, 13, 2098−2105.
in porphyrins and porphyrinoids. In Aromaticity in Heterocyclic
Compounds; Krygowski, T. M., Ed.; Springer: Berlin/Heidelberg,
2009; pp 83−154.
(87) Li, X. Y.; Sun, H. J.; Florke, U.; Klein, H. F. Organometallics
2005, 24, 4347−4350.
(56) Vogel, E.; Rohrig, P.; Sicken, M.; Knipp, B.; Herrmann, A.; Pohl,
̈
(88) Taube, R.; Langlotz, J.; Sieler, J.; Gelbrich, T.; Tittes, K.
J. Organomet. Chem. 2000, 597, 92−104.
M.; Schmickler, H.; Lex, J. Angew. Chem., Int. Ed. Engl. 1989, 28,
1651−1655.
(89) O’Connor, A. R.; White, P. S.; Brookhart, M. J. Am. Chem. Soc.
2007, 129, 4142−4143.
(57) Stepien
5117.
, M.; Latos-Grazyn
̨
(90) Bach, I.; Porschke, K. R.; Proft, B.; Goddard, R.; Kopiske, C.;
Kruger, C.; Rufinska, A.; Seevogel, K. J. Am. Chem. Soc. 1997, 119,
3773−3781.
(58) Skonieczny, J.; Latos-Grazyn
J. 2008, 4861−4874.
(59) Nervi, C.; Gobetto, R.; Milone, L.; Viale, A.; Rosenberg, E.;
Rokhsana, D.; Fiedler, J. Chem.Eur. J. 2003, 9, 5749−5756.
(60) Mysliborski, R.; Latos-Grazynski, L.; Szterenberg, L. Eur. J. Org.
́ ́
̇
Chem. 2006, 3064−3068.
(61) Chmielewski, P. J.; Latos-Grazyn
(91) Bach, I.; Porschke, K. R.; Goddard, R.; Kopiske, C.; Kruger, C.;
Rufinska, A.; Seevogel, K. Organometallics 1996, 15, 4959−4966.
(92) Pulst, S.; Arndt, P.; Heller, B.; Baumann, W.; Kempe, R.;
Rosenthal, U. Angew. Chem., Int. Ed. Engl. 1996, 35, 1112−1115.
(93) Bennett, M. A.; Johnson, J. A.; Willis, A. C. Organometallics
1996, 15, 68−74.
5231−5235.
(62) Lisowski, J.; Latos-Grazyn
(94) Edelbach, B. L.; Lachicotte, R. J.; Jones, W. D. Organometallics
1999, 18, 4660−4668.
1992, 31, 1933−1940.
(63) Latos-Grazyn
̇
́
(95) Latos-Grazynski, L.; Olmstead, M. M.; Balch, A. L. Inorg. Chem.
̇
Porphyrins and Metalloporphyrins. In The Porphyrin Handbook;
Kadish, K. M., Smith, K. M., Guilard, R., Eds.; Academic Press: New
York, 2000; pp 361−416.
1989, 28, 4065−4066.
(96) Latos-Grazynski, L.; Lisowski, J.; Olmstead, M. M.; Balch, A. L.
́
̇
Inorg. Chem. 1989, 28, 1183−1188.
(64) Pacholska-Dudziak, E.; Latos-Grazyn
2007, 2594−2608.
(65) Ram, M. S.; Riordan, C. G.; Yap, G. P. A.; Liables-Sands, L.;
Rheingold, A. L.; Marchaj, A.; Norton, J. R. J. Am. Chem. Soc. 1997,
119, 1648.
(97) Pohl, M.; Schmickler, H.; Lex, J.; Vogel, E. Angew. Chem., Int. Ed.
Engl. 1991, 30, 1693−1697.
(98) Cissell, J. A.; Vaid, T. P.; Rheingold, A. L. J. Am. Chem. Soc.
2005, 127, 12212−12213.
(99) Cissell, J. A.; Vaid, T. P.; Yap, G. P. A. Org. Lett. 2006, 8, 2401−
2404.
(66) Klaui, W.; Huhn, M.; Herbst-Irmer, R. J. Organomet. Chem.
̈
1991, 415, 133−142.
(100) Cissell, J. A.; Vaid, T. P.; Yap, G. P. A. J. Am. Chem. Soc. 2007,
129, 7841−7847.
(67) Chmielewski, P. J.; Latos-Grazyn
Chem. Soc. 1996, 118, 5690−5701.
(101) Yamamoto, Y.; Yakamoto, A.; Furuta, S.; Horie, M.; Kodama,
M.; Satao, W.; Akiba, K.; Tsuzuki, S.; Uchimaru, T.; Hashizume, D.;
Iwasaki, F. J. Am. Chem. Soc. 2005, 127, 14540−14541.
(102) Yamamoto, Y.; Hirata, Y.; Kodama, M.; Yamaguchi, T.;
Matsukawa, S.; Akiba, K. y.; Hashizume, D.; Iwasaki, F.; Muranaka, A.;
Uchiyama, M.; Chen, P.; Kadish, K. M.; Kobayashi, N. J. Am. Chem.
Soc. 2010, 132, 12627−12638.
(68) Latos-Grazyn
M.; Olmstead, M. M.; Balch, A. L. Inorg. Chem. 1994, 33, 192−197.
(69) Szyszko, B.; Latos-Grazyn
ski, L.; Lisowski, J.; Chmielewski, P. J.; Grzeszczuk,
̇
Int. Ed. 2011, 50, 6587−6591.
(70) Bondi, A. J. Phys. Chem. 1964, 68, 441−451.
(71) Hahn, C.; Vitagliano, A.; Giordano, F.; Taube, R. Organo-
metallics 1998, 17, 2060−2066.
(103) Wiberg, K. B. Tetrahedron 1968, 24, 1083−1096.
(104) Chen, Z.; Wannere, C. S.; Corminboeuf, C.; Puchta, R.;
Schleyer, P. Chem. Rev. 2005, 105, 3842−3888.
(72) Rettig, M. F.; Wing, R. M.; Wiger, G. R. J. Am. Chem. Soc. 1981,
103, 2980−2986.
(73) Ghebreyessus, K. Y.; Ellern, A.; Angelici, R. J. Organometallics
2005, 24, 1725−1736.
(74) Miki, K.; Shiotani, O.; Kai, Y.; Kasai, N.; Kanatani, H.;
Kurosawa, H. Organometallics 1983, 2, 585−593.
(75) Smith, D. E.; Welch, A. J. Acta Crystallogr., Sect. C 1986, 42,
1717−1720.
(76) Orpen, A. G.; Brammer, L.; Allen, F. H.; Kennard, O.; Watson,
D. G.; Taylor, R. J. Chem. Soc., Dalton Trans. 1989, S1−S83.
(77) Binotti, B.; Bellachioma, G.; Cardaci, G.; Macchioni, A.;
Zuccaccia, C.; Foresti, E.; Sabatino, P. Organometallics 2002, 21, 346−
354.
(78) Klein, A.; Luening, A.; Ott, I.; Hamel, L.; Neugebauer, M.;
Butsch, K.; Lingen, V.; Heinrich, F.; Elmas, S. J. Organomet. Chem.
2010, 695, 1898−1905.
(79) Kang, M.; Sen, A. Organometallics 2004, 23, 5396−5398.
(80) Meinhard, D.; Hollmann, F.; Huhn, W.; Thewalt, U.; Klinga,
M.; Rieger, B. Organometallics 2004, 23, 5637−5639.
(81) Ciajolo, R.; Jama, M. A.; Tuzi, A.; Vitagliano, A. J. Organomet.
Chem. 1985, 295, 233−238.
(82) Berenguer, J. R.; Fornies, J.; Lalinde, E.; Martinez, F.
Organometallics 1996, 15, 4537−4546.
(105) Schleyer, P.; Meaerker, C.; Dransfeld, A.; Jiao, H.; Hommes,
N. J. R. J. Am. Chem. Soc. 1996, 118, 6317−6318.
́
(106) Cyranski, M. K.; Krygowski, T. M.; Wisiorowski, M.; Hommes,
N. J. R.; Schleyer, P. Angew. Chem., Int. Ed. Engl. 1998, 37, 177−180.
(107) Juselius, J.; Sundholm, D. J. Org. Chem. 2000, 65, 5233−5237.
(108) Simkowa, I.; Latos-Grazyn
ski, L.; Stepien
́
̇
̨
Int. Ed. 2010, 49, 7665−7669.
́ ́
(109) Stepien, M.; Latos-Grazyn
̇
̨
2007, 72, 2259−2270.
(110) Furuta, H.; Maeda, H.; Osuka, A. J. Org. Chem. 2001, 66,
8563−8572.
(111) Toganoh, M.; Furuta, H. J. Org. Chem. 2010, 75, 8213−8223.
(112) Castro, C.; Isborn, C. M.; Karney, W. L.; Mauksch, M.;
Schleyer, P. Org. Lett. 2002, 4, 3431−3434.
(113) Pacholska-Dudziak, E.; Skonieczny, J.; Pawlicki, M.; Latos-
Grazyn
ski, L.; Szterenberg, L. Inorg. Chem. 2005, 44, 8794−8803.
̇
(114) Pacholska-Dudziak, E.; Latos-Grazyn
2009, 253, 236−248.
(115) Ulman, A.; Manassen, J. J. Chem. Soc., Perkin Trans. 1 1979,
1066−1069.
ski, L. Coord. Chem. Rev.
̇
3259
dx.doi.org/10.1021/ic2027175 | Inorg. Chem. 2012, 51, 3247−3260

Inorganic Chemistry
Article
(116) SHELXL97Program for Crystal Structure Refinement;
University of Gottingen: Gottingen, Germany, 1997.
̈
̈
(117) SHELXS97Program for Crystal Structure Solution; University
of Gottingen: Gottingen, Germany, 1997.
̈
̈
(118) Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.;
Robb, M. A.; Cheeseman, J. R.; Scalmani, G.; Barone, V.; Mennucci,
B.; Petersson, G. A.; Nakatsuji, H.; Caricato, M.; Li, X.; Hratchian,
H. P.; Izmaylov, A. F.; Bloino, J.; Zheng, G.; Sonnenberg, J. L.; Hada,
M.; Ehara, M.; Toyota, K.; Fukuda, R.; Hasegawa, J.; Ishida, M.;
Nakajima, T.; Honda, Y.; Kitao, O.; Nakai, H.; Vreven, T.;
Montgomery, J. A., Jr.; Peralta, J. E.; Ogliaro, F.; Bearpark, M.;
Heyd, J. J.; Brothers, E.; Kudin, K. N.; Staroverov, V. N.; Kobayashi,
R.; Normand, J.; Raghavachari, K.; Rendell, A.; Burant, J. C.; Iyengar,
S. S.; Tomasi, J.; Cossi, M.; Rega, N.; Millam, N. J.; Klene, M.; Knox,
J. E.; Cross, J. B.; Bakken, V.; Adamo, C.; Jaramillo, J.; Gomperts, R.;
Stratmann, R. E.; Yazyev, O.; Austin, A. J.; Cammi, R.; Pomelli, C.;
Ochterski, J. W.; Martin, R. L.; Morokuma, K.; Zakrzewski, V. G.;
Voth, G. A.; Salvador, P.; Dannenberg, J. J.; Dapprich, S.; Daniels,
̈
A. D.; Farkas, O.; Foresman, J. B.; Ortiz, J. V.; Cioslowski, J.; Fox, D. J.
Gaussian 09, revision A.1; Gaussian, Inc.: Wallingford, CT, 2009.
(119) Lee, C.; Yang, W.; Parr, R. G. Phys. Rev. B 1988, 37, 785−789.
(120) Becke, A. D. Phys. Rev. A 1988, 38, 3098−3100.
(121) Glendening, E. D.; Reed, A. E.; Carpenter, I. J.; Weinhold, F.
The NBO3.0 program; University of Wisconsin: Madison, MI, 1996.
3260
dx.doi.org/10.1021/ic2027175 | Inorg. Chem. 2012, 51, 3247−3260