Core-modified porphyrin incorporating a phenolate donor. Characterization of Pd(II), Ni(II), Zn(II), Cd(II), and Fe(III) complexes

Article abstract of DOI:10.1021/ic0345121

Coordinating properties of acetoxybenziporphyrin, (TPBPOAc)H, have been investigated for a number of metal ions. Insertion of Ni, Pd, and Fe results in the cleavage of the acetoxy group leading to complexes (TPBPO)Ni^II, (TPBPO)Pd^II, and (TPBPO)Fe^IIIX containing a M-O bond. No cleavage is observed with Zn(II) and Cd(II), which form complexes (TPBPOAc)M^IICl, where M = Zn, Cd. (TPBPO)Ni^II can also be obtained from the dication of hydroxybenziporphyrin, [(TPBPOH)H ₃]Cl₂, which is prepared by acid hydrolysis of the acetoxy compound. The diamagnetic (TPBPO)Ni^II can be transformed into the paramagnetic (TPBPOAc)Ni^IICl in a reaction with acetyl chloride. X-ray structures have been determined for (TPBPO)Pd^II and (TPBPOAc)Zn^IICl. In the palladium species, the phenolate moiety forms a strong bond to the Pd ion and an unusual interaction geometry is observed, enforced by the macrocyclic environment. Association of a TFA molecule to the phenolic oxygen does not cause significant structural changes in the (TPBPO)Pd^II molecule. In (TPBPOAc)Zn^IICl, the metal ion weakly interacts with the phenolic fragment. The paramagnetic Fe(III) complexes, (TPBPO)Fe^IIIX, have been investigated with ¹H NMR spectroscopy. The observed spectral patterns are consistent with the presence of a high-spin Fe(III) center and π delocalization of spin density onto the phenoxide fragment. Each of the compounds (TPBPO)Fe^IIIX exists in solution as a mixture of two isomers, which for X = I are shown to remain in a temperature-dependent equilibrium. The observed isomerism results from two nonequivalent orientations of the axial halide with respect to the puckered macrocyclic ring.

Full text of DOI:10.1021/ic0345121

Inorg. Chem. 2003, 42, 6183−6193
Core-Modified Porphyrin Incorporating a Phenolate Donor.
Characterization of Pd(II), Ni(II), Zn(II), Cd(II), and Fe(III) Complexes
Marcin Ste¸pien´ and Lechosław Latos-Graz3yn´ski*
Department of Chemistry, UniVersity of Wrocław,14 F. Joliot-Curie St., Wrocław 50 383, Poland
Received May 14, 2003
Coordinating properties of acetoxybenziporphyrin, (TPBPOAc)H, have been investigated for a number of metal
ions. Insertion of Ni, Pd, and Fe results in the cleavage of the acetoxy group leading to complexes (TPBPO)NiII,
II
III
(TPBPO)Pd , and (TPBPO)Fe X containing a M−O bond. No cleavage is observed with Zn(II) and Cd(II), which
form complexes (TPBPOAc)M Cl, where M ) Zn, Cd. (TPBPO)NiII can also be obtained from the dication of
II
hydroxybenziporphyrin, [(TPBPOH)H ]Cl2, which is prepared by acid hydrolysis of the acetoxy compound. The
3
diamagnetic (TPBPO)NiII can be transformed into the paramagnetic (TPBPOAc)NiIICl in a reaction with acetyl chloride.
II
II
X-ray structures have been determined for (TPBPO)Pd and (TPBPOAc)Zn Cl. In the palladium species, the phenolate
moiety forms a strong bond to the Pd ion and an unusual interaction geometry is observed, enforced by the
macrocyclic environment. Association of a TFA molecule to the phenolic oxygen does not cause significant structural
II
II
changes in the (TPBPO)Pd molecule. In (TPBPOAc)Zn Cl, the metal ion weakly interacts with the phenolic fragment.
The paramagnetic Fe(III) complexes, (TPBPO)Fe X, have been investigated with 1H NMR spectroscopy. The observed
III
spectral patterns are consistent with the presence of a high-spin Fe(III) center and π delocalization of spin density
III
onto the phenoxide fragment. Each of the compounds (TPBPO)Fe X exists in solution as a mixture of two isomers,
which for X ) I are shown to remain in a temperature-dependent equilibrium. The observed isomerism results
from two nonequivalent orientations of the axial halide with respect to the puckered macrocyclic ring.
Introduction
p-phenylene,8 semiquinone,9-11 cycloheptatriene,12,13 in-
dene,12,14 azulene,15-18 cyclopentadiene,19 or 2,4-linked
thiophene.20
One of the primary goals driving the search for new core-
modified porphyrins is the synthesis of macrocycles that
provide a favorable environment to stabilize less-common
coordination modes between metal ions and a donor of
choice.1 This goal is well exemplified by the coordination
properties of carbaporphyrinoids, a novel class of macro-
cycles capable of generating rich organometallic chemistry.1-5
Their construction formally requires a modification of the
porphyrin skeleton that would provide a CH unit in place of
one of the nitrogens. It is effected by replacing one pyrrole
ring by an appropriate moiety, such as m-phenylene,6,7
Some of the resultant molecules can be derivatized by
exploiting their inherent reactivity. When the reaction affects
the exterior of the macrocycle, the (N,N,N,C) coordination
(7) Ste¸pien´, M.; Latos-Graz˘yn´ski, L. Chem.-Eur. J. 2001, 7, 5113.
(8) Ste¸pien´, M.; Latos-Graz˘yn´ski, L. J. Am. Chem. Soc. 2002, 124, 3838.
(9) Lash, T. D. Angew. Chem., Int. Ed. Engl. 1995, 34, 2533.
(10) Lash, T. D.; Chaney, S. T.; Richter, D. T. J. Org. Chem. 1998, 63,
9076.
(11) Liu, D.; Lash, T. D. Chem. Commun. 2002, 2426.
(12) Berlin, K.; Steinbeck, C.; Breitmaier, E. Synthesis 1996, 336.
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(14) Lash, T. D.; Hayes, M. J. Angew. Chem., Int. Ed. Engl. 1997, 36,
840.
* Author to whom correspondence should be addressed. E-mail: llg@
wchuwr.chem.uni.wroc.pl.
(1) Latos-Graz˘yn´ski, L. Core Modified Heteroanalogues of Porphyrins
and Metalloporphyrins. The Porphyrin Handbook; Kadish, K. M.,
Smith, K. M., Guilard, R., Eds.; Academic Press: New York, 2000;
Vol. 2, Chapter 14, pp 361-416.
(2) Chmielewski, P. J.; Latos-Graz˘yn´ski, L.; Rachlewicz, K.; Głowiak,
T. Angew. Chem., Int. Ed. Engl. 1994, 33, 779.
(15) Lash, T. D.; Chaney, S. T. Angew. Chem., Int. Ed. Engl. 1997, 36,
839.
(16) Lash, T. D. Chem. Commun. 1998, 1683.
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J.; Chandrashekar, T. K.; Teng, W.; Ruhlandt-Senge, K. Chem.
Commun. 2002, 1660.
(3) Furuta, H.; Asano, T.; Ogawa, T. J. Am. Chem. Soc. 1994, 116, 767.
(4) Lash, T. D. Synlett 1999, 279.
(5) Furuta, H.; Maeda, H.; Osuka, A. Chem. Commun. 2002, 1795.
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2002, 41, 1371.
(19) Berlin, K. Angew. Chem., Int. Ed. Engl. 1996, 35, 1820.
(20) Sprutta, N.; Latos-Graz˘yn´ski, L. Tetrahedron Lett. 1999, 40, 8457.
10.1021/ic0345121 CCC: $25.00 © 2003 American Chemical Society
Published on Web 09/09/2003
Inorganic Chemistry, Vol. 42, No. 20, 2003 6183

Ste¸pien´ and Latos-Graz3yn´ski
Scheme 1
Scheme 2
core of a carbaporphyrinoid is preserved although the
structure may otherwise be deeply altered.16,20-26 If, however,
the substitution takes place at the internal carbon, the
coordinating properties of the molecule are directly affected.27
In some cases, a potential donor atom is actually introduced,
leading to a new type of porphyrin-related ligand.28,29 The
metal-donor bond can be firmly held in the cavity of such
a ligand so that possible dissociation will be impaired.
This approach was explored for regular porphyrins, as
examplified by the coordination of porphyrin N-oxide,30-33
insertion of vinylidene carbene into the Fe-N nitrogen bond
of iron porphyrin,33-35 or isolation of the bridging methylene
complex Ru(OEP-N-µ-CH2-)(CH3).36 In those compounds,
oxygen and carbon donors were introduced into the porphyrin
core leading to peculiar coordination environments, (N,N,N,O-
(N)) and (N,N,N,C(N)).
isomers, only the alkyl-substituted form of 2 was reported
until now.9 It exists preferentially as the 18-electron aromatic
keto tautomer 2′ and, hence, was called 2-oxybenziporphyrin.
Such an aromatic tautomer is not available for 1 or 3. A
disubstituted compound, 2-oxy-4-hydroxybenziporphyrin,
was reported subsequently.37 8,19-Dimethyl-9,13,14,18-tet-
raethyl-2-oxybenziporphyrin coordinated palladium(II) to
form the four-coordinate anionic complex [(OBP)PdII]-.38
The NMR data provided evidence for the retention of
macrocyclic aromaticity and coordination via a carbon
σ-donor. The phenolic structure of type 2 could be restored
by protonation or alkylation of the external oxygen.
In the course of our studies on coordinating properties of
6,11,16,21-tetraphenyl-m-benziporphyrin, we found that in
the reaction with silver(I) acetate, the macrocycle was
selectively acetoxylated at the internal carbon atom yielding
22-acetoxy-6,11,16,21-tetraphenyl-m-benziporphyrin (4).7 X-
ray structural analysis of 4 confirmed that the benzene ring
built into the framework of acetoxy-m-benziporphyrin com-
pletely blocks macrocyclic delocalization while retaining the
unperturbed [6]annulene aromaticity, similar to the substrate
m-benziporphyrin.
Compound 4 can be viewed as an O-protected 22-hydroxy-
6,11,16,21-tetraphenyl-m-benziporphyrin (5), corresponding
to the phenolic structure 1. Symbols (TPBPOAc)H and
(TPBPOH)H will be adopted for 4 and 5, respectively, to
denote the internal substitution. Deprotection of the OH
group in 4 can, in principle, be carried out by either acid
hydrolysis or metal insertion. In the latter case, 4 would lead
directly to complexes of 5, thus obviating the hydrolysis step.
Cleavage of the ester function may depend on reaction
A natural modification of this type that can be applied to
m-benziporphyrin is the introduction of a phenolate donor
to the coordination core. The pertinent compound, 22-
hydroxybenziporphyrin (1) is one of three isomeric benzi-
porphyrins containing a phenolic function, the other two
being 2-hydroxy- and 3-hydroxybenziporphyrin (2 and 3,
respectively). These species correspond to the three distinct
ways of incorporating a phenol moiety into the porphyrin
macrocycle. In 2 and 3, the (N,N,N,C) coordination core is
retained, while in 1 it becomes (N,N,N,O(C)). Of the three
(21) Chmielewski, P. J.; Latos-Graz˘yn´ski, L. J. Chem. Soc., Perkin Trans.
2 1995, 503.
(22) Chmielewski, P. J.; Latos-Graz˘yn´ski, L.; Głowiak, T. J. Am. Chem.
Soc. 1996, 118, 5690.
(23) Schmidt, I.; Chmielewski, P. J. Tetrahedron Lett. 2001, 42, 1151.
(24) Schmidt, I.; Chmielewski, P. J.; Ciunik, Z. J. Org. Chem. 2002, 67,
8917.
(25) Furuta, H.; Maeda, H.; Osuka, A.; Yasutake, M.; Shinmyozu, T.;
Ishikawa, Y. Chem. Commun. 2000, 1143.
(26) Furuta, H.; Ishizuka, T.; Osuka, A.; Ogawa, T. J. Am. Chem. Soc.
1999, 121, 2945.
(27) Ishikawa, Y.; Yoshida, I.; Akaiwa, K.; Koguchi, E.; Sasaki, T.; Furuta,
H. Chem. Lett. 1997, 453.
(28) Hayes, M. J.; Spence, J. D.; Lash, T. D. Chem. Commun. 1998, 2409.
(29) Hung, C.-H.; Chen, W.-C.; Lee, G.-H.; Peng, S.-M. Chem. Commun.
2002, 1516.
(30) Balch, A. L.; Chan, Y. W.; Olmstead, M. M. J. Am. Chem. Soc. 1986,
107, 6510.
(31) Groves, J. T.; Watanabe, Y. J. Am. Chem. Soc. 1988, 110, 8443.
(32) Tsurumaki, H.; Watanabe, Y.; Morishima, I. J. Am. Chem. Soc. 1993,
115, 11784.
(33) Rachlewicz, K.; Latos-Graz˘yn´ski, L. Inorg. Chem. 1996, 35, 1136.
(34) Chevrier, B.; Weiss, R.; Chottard, J.-C.; Lange, M.; Mansuy, D. J.
Am. Chem. Soc. 1981, 103, 2899.
(35) Latos-Graz˘yn´ski, L.; Cheng, R.-J.; La Mar, G. N.; Balch, A. L. J.
Am. Chem. Soc. 1981, 103, 4270.
(37) Richter, D. T.; Lash, T. D. Tetrahedron 2001, 57, 3657.
(38) Ste¸pien´, M.; Latos-Graz˘yn´ski, L.; Lash, T. D.; Szterenberg, L. Inorg.
Chem. 2001, 40, 6892.
(36) Seyler, J. W.; Safford, L. K.; Fanwick, P. E.; Leidner, C. R. Inorg.
Chem. 1992, 31, 1545.
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Core-Modified Porphyrin Incorporting Phenolate Donor
Figure 1. Electronic spectrum of [5-H2]Cl2 (CH2Cl2, 298 K).
conditions and the choice of metal, making acetoxybenzi-
porphyrin a versatile ligand.
Figure 2. 1H NMR spectrum of [5-H2]Cl2 (CD2Cl2, 233 K). The high-
field region is expanded in the upper trace.
Removal of the acetyl group should enable phenoxide
coordination supported in a peculiar arrangement by the
porphyrinoid ring, similar to the complexes of other mac-
rocyclic39 and pincer ligands.40
In this account, we describe the structure and spectroscopic
properties of complexes formed by insertion of Ni, Pd, Zn,
Cd, and Fe ions into 22-acetoxy-m-benziporphyrin or 22-
hydroxy-m-benziporphyrin. In the case of paramagnetic
systems, the relation between paramagnetic shifts and the
molecular structure will be discussed in detail.
Results and Discussion
Formation and Characterization of 22-Hydroxy-6,11,-
16,21-tetraphenyl-m-benziporphyrin (5). Complexes of
(TPBPOH)H have usually been obtained directly from
acetoxybenziporphyrin, which is a readily available derivative
of m-benziporphyrin.7 Metal insertion and acetyl removal
are combined in these reactions, making the preparation of
5 unnecessary. Hydroxybenziporphyrin has been prepared,
however, to investigate its own reactivity toward metal ions,
especially those that do not induce ester cleavage in
acetoxybenziporphyrin (Zn(II), Cd(II)).
Figure 3. 1H NMR spectra (CDCl3, 298 K) of 6-Ni (trace A) and 6-Pd
(trace B).
Scheme 3
Compound 5 has been obtained as the dichloride salt by
refluxing a chloroform solution of 4 with concentrated
hydrochloric acid for 2 h and subsequent precipitation with
n-hexane. Electronic and 1H NMR spectra of [5-H2]Cl2 are
shown in Figures 1 and 2, respectively. They are similar to
the corresponding spectra obtained for the protonated m-
benziporphyrin, reflecting similarities in the electronic and
molecular structure. In the 1H NMR spectrum, the resonances
of exchangeable protons 22-OH, 23,25-NH, and 24-NH have
been identified at 9.43, 12.12, and 8.04 ppm (CD2Cl2, 233
K). The latter two signals show four-bond scalar couplings
to the corresponding â-pyrrole resonances (4JHH ≈ 1 Hz).
Proton 22-OH could be assigned using the correlations to
22-C and 1,5-C found in the heteronuclear multiple-bond
correlation (HMBC) map.
The dicationic form is stable, providing that it is protected
from loss of HCl. Deprotonation in solution results in
complex equlibria, which are currently under investigation.
Formation and Characterization of (TPBPO)NiII and
(TPBPO)PdII. Insertion of nickel(II) chloride to 4 in
acetonitrile results in the formation of a four-coordinate
diamagnetic complex, (TPBPO)NiII (6-Ni) in 74% yield
(Scheme 3). The same complex was obtained by reacting
[5-H2]Cl2 with NiCl2. The palladium species (TPBPO)PdII
(6-Pd) was obtained analogously.
The 1H NMR spectra of 6-Ni and 6-Pd are presented in
Figure 3. NMR data are consistent with the formation of
four-coordinate complexes. The 1H and 13C resonances
corresponding to the CH3 and CO fragments of the free
(39) Olmstead, M. M.; Sigel, G.; Hope, H.; Xu, X.; Power, P. P. J. Am.
Chem. Soc. 1985, 107, 8087.
(40) van der Boom, M. E.; Liou, S.-Y.; Ben-David, Y.; Shimon, L. J. W.;
Milstein, D. J. Am. Chem. Soc. 1998, 120, 6531.
Inorganic Chemistry, Vol. 42, No. 20, 2003 6185

Ste¸pien´ and Latos-Graz3yn´ski
is 62.1°. The 6,21 meso carbons are displaced from the N3
plane in the direction opposite to the oxygen atom, but the
remaining part of the macrocycle is only slightly ruffled.
Similar conformation was observed in the nickel(II) com-
plexes of the octaethylporphyrin-N-oxide dianion,30 where
the oxygen was inserted between the nickel ion and one of
the porphyrin nitrogens.
The strain is most noticeable in the C(22)-O-Pd bond
angle, which is contracted to 99.6(1)°. A similar geometry,
with the Cipso-O-Pd angle of 98.85(14)° was found in the
palladium pincer phenoxide of Milstein et al.40 On the other
hand, in the Pd(II) complex of a substituted salicylaldimine,42
where no strain is present, the pertinent angle is 127.4(3)°.
Similar values are observed for other metal phenoxides where
no restraint is imposed by the ligand structure.39,43-45
As a result of the strain, the Pd‚‚‚C(22) distance is only
2.571(2) Å, significantly less than the sum of van der Waals
radii (1.63 Å for Pd and 1.77 Å for C).46 It is, however, still
larger than that normally observed for Pd-C bond lengths.
The environment of C(22) is planar despite the proximity
of the Pd ion, suggesting that the Pd‚‚‚C(22) interaction has
little if any bonding character.
When (TPBPO)PdII was crystallized in the presence of
trifluoroacetic acid, another crystal form was obtained
containing the adduct (TPBPO)PdII TFA. In the X-ray
structure (Figure 4, bottom), a molecule of TFA associates
to the phenolic oxygen of 6-Pd via a hydrogen bond (1.51
Å), which forms an angle of ca. 37° with the molecular
symmetry plane of 6-Pd. Formation of the H-bond does
not influence significantly the structural parameters of the
(TPBPO)PdII molecule. The structure of the acid adduct
shows that (TPBPO)PdII is not protonated by TFA in the
solid state, implying low basicity of the Pd-coordinated
phenolate.
Paramagnetic Ni(II) Complexes. When a solution of
(TPBPO)NiII (6-Ni) is treated with gaseous hydrogen
chloride, a new species is formed that can be formulated as
(TPBPOH)NiIICl (7-Ni, Scheme 4). A similar process can
be carried out with acetyl chloride yielding (TPBPOAc)NiII-
Cl (8-Ni). Interestingly, no reaction is observed with acetic
acid or acetic anhydride. The reactions are reversed by
refluxing the products in chloroform. (TPBPOH)NiIICl and
(TPBPOAc)NiIICl are, however, hydrolytically unstable and
in the presence of excess HCl or AcCl slowly decompose to
the respective free ligands.
Both (TPBPOH)NiIICl and (TPBPOAc)NiIICl are para-
magnetic. The 1H NMR spectrum of the latter compound is
presented in Figure 5A. It resembles the spectra observed
for other high-spin Ni(II) complexes of core-modified
porphyrins.1 The pyrrolic â-H resonances and the 2,4-H
signal are shifted to low field, while 3-H and the acetoxy
methyl group have their resonances in the upfield region.
Figure 4. Crystal structure diagrams of 6-Pd‚CDCl3 (top) and 6-Pd‚
TFA‚2CDCl3 (bottom). Thermal ellipsoids are at the 50% probability level.
N atoms are shaded in gray and O atoms in black. H atoms and solvent
molecules are omitted for clarity. Phenyl substituents are not shown in the
side views. The TFA molecule is drawn in gray lines.
acetoxybenziporphyrin (4) are missing in the respective
spectra, confirming the absence of the acetyl group.
Crystal Structure of (TPBPO)PdII. The structure of
6-Pd, determined in an X-ray diffraction study, is shown
in Figure 4 (top). The coordination environment of the Pd
ion is roughly square planar and is constituted by three
pyrrolic donors and one phenoxide donor. The Pd-N
distances are in the limits found for palladium(II) porphy-
rins,41 although the Pd-N(24) bond length of 1.981(2) Å is
noticeably smaller than the remaining two (2.013(2) and
2.010(2) Å). The Pd-O bond length of 1.992(1) Å is similar
to that determined in a palladium(II) phenoxy pincer ligand
complex (2.041(2) Å)40 and comparable to the distance found
in the palladium(II) complexes of a substituted salicylaldi-
mine (1.982(4) Å).42 The C(22)-O distance (1.326(2) Å) is
typical of phenoxide ligands.
The coordination square is slightly ruffled with angles
N(24)-Pd-O(22) and N(23)-Pd-(N25) equal to 167.1(1)
and 175.2(1)°, respectively. The cis X-Pd-Y angles (X, Y
) N, O) fall in the range of 87-92°. The Pd atom lies 0.08
Å away from the mean N3O plane, which is less than the
mean deviation of the four donor atoms (0.14 Å).
Introduction of the additional oxygen into the coordination
core causes strain, which is partly relieved by bending the
phenolate moiety out of the macrocyclic plane (the phenolate
itself remains planar). The dihedral angle between the plane
of the phenolate (C6O) and that of the three nitrogens (N3)
(43) Balch, A. L.; Latos-Graz˘yn´ski, L.; Noll, B. C.; Olmstead, M. M.;
Zovinka, E. P. Inorg. Chem. 1992, 31, 1148.
(41) Stolzenberg, A. M.; Schussel, L.; Summers, J. S.; Foxman, B. M.;
Petersen, J. L. Inorg. Chem. 1992, 31, 1678.
(42) Miller, K. J.; Baag, J. H.; Abu-Omar, M. M. Inorg. Chem. 1999, 38,
4510.
(44) Darensbourg, D. J.; Widelson, J. R.; Lewis, S. J.; Yarbrough, J. C. J.
Am. Chem. Soc. 2002, 124, 7075.
(45) Redshaw, C.; Elsegood, M. R. J. Inorg. Chem. 2000, 39, 5164.
(46) Bondi, A. J. Phys. Chem. 1964, 68, 441.
6186 Inorganic Chemistry, Vol. 42, No. 20, 2003

Core-Modified Porphyrin Incorporting Phenolate Donor
Scheme 4
Figure 5. 1H NMR spectrum of 8-Ni (trace A, 298 K, CDCl3). The
diamagnetic region is not shown. Trace B shows the 1H NMR spectrum of
the intermediates forming during Ni(II) insertion to 4. Concentration ratio
of the two species is 8.9:1.
To check if any of the two paramagnetic species is an
intermediate in the Ni(II) insertion to acetoxybenziporphyrin,
the reaction was stopped after a 5 min reflux and worked
up in the usual way (see Experimental Section), except for
the crystallization step. The 1H NMR spectrum of the product
mixture is shown in Figure 5 (trace B, the diamagnetic
region, where the signals of (TPBPO)NiII were present, is
not shown). Two paramagnetic species are present, one of
which can be identified as (TPBPOAc)NiIICl (8-Ni) based
on the chemical shifts. The spectral pattern observed for the
other, more abundant species does not match (TPBPOH)-
NiIICl, which has similar shift values as (TPBPOAc)NiIICl.
The new species, which could not be generated from the
diamagnetic 6-Ni, is probably a nickel(II) acetoxybenzipo-
rhyrin with unspecified axial ligation. The ligands that should
be taken into acount are the chloride originating from the
metal carrier, the acetate released during insertion, and
acetonitrile.
Figure 6. Crystal structure diagram of 8-Zn‚2CD2Cl2 with thermal
ellipsoids at the 50% probability level. Hydrogen atoms and solvent
molecules are omitted for clarity. The bottom part of the figure compares
the solid-state conformations of 8-Zn (A), 4 (B, with a hydrogen bonded
water molecule), and 6-Pd (C).
insertions (resulting in 6-Ni and 6-Pd) is probably caused
by a greater electrophilicity of the d8 ions accompanied by
their tendency to form tetracoordinate planar complexes.
It is possible to generate (TPBPO)ZnII (6-Zn) starting
from the 22-hydroxybenziporphyrin dication. An unstable
compound with a spectrum similar to 6-Ni and 6-Pd could
1
be observed in the H NMR spectrum of product mixture
but was not isolated in pure form.
Crystal Structure of (TPBPOAc)ZnIICl. The structure
of (TPBPOAc)ZnIICl, determined in an X-ray diffraction
study, is shown in Figure 6. In the crystal, the molecule of
8-Zn is located on a crystallographic symmetry plane (m)
accompanied by two dichloromethane molecules, one of
which is disordered. The acetoxy methyl group shows
rotational disorder and was refined in two equally populated
orientations. Conformation of the macrocycle closely re-
sembles that of the water adduct of acetoxy-m-benziporphy-
rin7 (Figure 6).
Other Diamagnetic Metal Ions. Zinc(II) and cadmium-
(II) are readily inserted into 22-acetoxy-m-benziporphyrin,
yielding exclusively the four-coordinate complexes (TPB-
POAc)ZnIICl (8-Zn) and (TPBPOAc)CdIICl (8-Cd), analog-
ous to the previously described (TPBPOAc)NiIICl (8-Ni).
The ester group is not cleaved during the insertion of Zn
and Cd even after prolonged reflux of the acetonitrile
solutions. The cleavage observed for Ni(II) and Pd(II)
Inorganic Chemistry, Vol. 42, No. 20, 2003 6187

Ste¸pien´ and Latos-Graz3yn´ski
Figure 7. Electronic spectrum of 9-I (CH2Cl2, 298 K).
Scheme 5
Figure 8. 1H NMR spectra (CDCl3, 323 K) of 9-Cl (trace A), 9-Br
(trace B), 9-I (trace C), and 9-I-d6 (trace D). The high- and low-field
part of each spectrum are not to scale.
The acetoxy group lies on the side opposite to the chloride.
The geometry around zinc can be described as a trigonal
bipyramid with the equatorial positions occupied by N(24),
the chloride, and the acetoxy-substituted phenylene ring. The
coordination bond lengths Zn-N(23), 2.080(3) Å; Zn-
N(24), 1.969(5) Å; Zn-N(25), 2.081(3) Å; and Zn-Cl,
2.261(1) Å are in the limits found for the zinc(II) porphyrins
and N-methyl porphyrins.47,48 The Zn‚‚‚C(22) and Zn‚‚‚O(22)
distances (2.794(6) and 2.748(4) Å, respectively) are smaller
than the corresponding sums of van der Waals radii (ca. 1.39
Å for Zn, 1.52 Å for O, and 1.77 Å for the benzene ring),46
indicating a weak, closed-shell interaction. The zinc ion is
located 0.58 Å away from the N3 plane.
Iron Complexes. Insertion of iron into acetoxy-m-benzi-
porphyrin (4) has been carried out by refluxing the ligand
and excess FeCl2 in a chloroform-acetonitrile solution in
the presence of atmospheric oxygen. The reaction results
yield a five-coordinate complex, (TPBPO)FeIIICl (9-Cl,
Scheme 5).
Presumably an iron(II) species (TPBPOAc)FeIICl is ini-
tially formed. Subsequently acetoxyl cleavage takes place,
similarly as during the insertion of Ni(II) and Pd(II),
accompanied by aerial oxidation of iron(II). No attempt was
made to detect the Fe(II) intermediates in the reaction
mixture.
Axial ligand exchange in (TPBPO)FeIIICl (9-Cl) was
accomplished by stirring a solution of the complex with
hydrobromic or hydriodic acid (see Experimental Section).
In this way, the bromoiron and iodoiron complexes (9-Br
and 9-I) were obtained. The electronic spectrum of 9-I is
shown in Figure 7.
The molecule of (TPBPO)FeIIIX has an effective Cs
symmetry, with the mirror plane passing through the iron
atom, chloride, and phenol oxygen. As a consequence, the
1H NMR spectrum will contain three pyrrole resonances (8,-
19-H, 9,18-H, and 13,14-H) and two phenol resonances
(2,4-H and 3-H, intensity ratio 2:1). Nonequivalence of the
two sides of the macrocycle will cause each phenyl ring to
have two distinct ortho and two meta resonances, unless the
rotation around the Cmeso-Cipso bond is sufficiently fast.49
The 1H NMR spectra of the paramagnetic (TPBPO)FeIIIX
(X ) Cl, Br, I) are shown in Figure 8. Resonance assign-
ments have been made on the basis of relative intensities
1
and site specific deuteration. The H NMR spectrum of
pyrrole-deuterated (TPBPO-d6)FeIIII is shown in Figure 8,
trace D.
Each of the compounds 9-X (X ) Cl, Br, I) is actually
a mixture of two isomers. They will be denoted 9a-X and
9b-X, isomer 9b being the more abundant. Relative amounts
of the two isomers were in each case estimated by careful
deconvolution of the downfield region of the spectrum, and
the results are given in Table 1. The concentration ratios
[9b-X]/[9a-X] determined at 323 K vary from about 2:1
for the chloride (9-Cl) to 4:1 for the iodide (9-I). The error
of these estimations may exceed 10%. Apparently, the
composition of the iodide species exhibits certain temperature
dependence varying from 6.6:1 at 213 K to 3.9:1 at 323 K
(Figure 9), indicating that the two isomers are actually in
dynamic equilibrium. Approximate thermodynamic param-
eters derived from these data are ∆H° ) -2.6(1) kJ/mol
and ∆S° ) 3.7(4) J/(mol K) (r2 ) 0.97).
(47) Lavallee, D. K.; Kopelove, A. B.; Anderson, O. P. J. Am. Chem. Soc.
1978, 100, 3025.
(48) Kuila, D.; Lavallee, D. K.; Schauer, C. K.; Anderson, O. P. J. Am.
Chem. Soc. 1984, 106, 448.
(49) Walker, F. A. Proton NMR and EPR Spectroscopy of Paramagnetic
Metalloporphyrins. The Porphyrin Handbook; Kadish, K. M., Smith,
K. M., Guilard, R., Eds.; Academic Press: San Diego, CA, 2000; Vol.
5, Chapter 36, pp 81-183.
6188 Inorganic Chemistry, Vol. 42, No. 20, 2003

Core-Modified Porphyrin Incorporting Phenolate Donor
Table 1. 1H NMR Chemical Shifts and Line Widths for Complexes
9-X, X ) Cl, Br, I
(TPBPO)FeIIICl
(TPBPO)FeIIIBr
(TPBPO)FeIIII
compound
pyrroles
(9-Cl)
(9-Br)
(9-I)
Major Isomer (9b) δ/ppm (ν1/2/kHz)
89 (1.4)
79 (1.5)
∼51 (1.1)
57 (0.9)
-69 (0.9)
91 (0.59)
80 (0.61)
53 (0.58)
56 (0.39)
-70 (0.30)
92 (0.25)
81 (0.24)
55 (0.26)
53 (0.22)
-71 (0.18)
2,4-H
3-H
Minor Isomer (9a) δ/ppm (ν1/2/kHz)
pyrroles
∼72 (∼1.4)
∼71 (∼1.4)
∼53 (1.1)
∼73 (∼1.4)
-155 (2.1)
2.1
75 (0.58)
71 (0.55)
52 (0.47)
77 (0.49)
-167 (0.88)
2.7
78 (0.26)
72 (0.24)
50 (0.26)
82 (0.27)
-180 (0.54)
3.9
2,4-H
3-H
[9b]/[9a]
Figure 10. Curie plot for 9-I (temperature range 213-323 K). Full dots
(solid lines) correspond to the major isomer (9b-I). Lines are not least-
squares fits and are for illustration only. Positive and negative parts of the
Y-axis are differently scaled.
to T-2, which was shown to correct for the pseudocontact
shifts.51
Addition of an excess of benzyltriethylammonium chloride
to a solution of (TPBPO)FeIIII in CDCl3 results in its
conversion to (TPBPO)FeIIICl, which is characterized by
identical isomeric composition to the sample obtained
directly from the insertion procedure. In a reverse experiment,
the chloride complex 9-Cl could not be converted into 9-I
even in the presence of a large excess of tetrabutylammonim
iodide.
Figure 9. Temperature dependence of the equilibrium constant K ) [9b-
I]/[9a-I]. Vertical bars correspond to an error of (10%. The line shows a
least-squares fit of the van’t Hoff equation (see text).
Addition of AgBF4 in CD3OD to a solution of (TPBPO)-
FeIIII transforms the complex into [(TPBPO)FeIII]BF4, the
iodide ligand being removed in the form of AgI. The
spectrum of the resulting solution contains only one set of
very broad resonances (1-3 kHz, the signal of 3-H was not
found). Addition of tetrabutylammonim iodide restores 9-I,
and the ratio of isomers is again exactly reproduced.
Coordination of a metal ion by 22-hydroxybenziporphyrin
imposes a steric constraint on the geometry of the ligand.
As can be seen in the structure of 6-Pd, the phenolate moiety
is positioned at an angle to the macrocyclic plane. In the
ferric complexes 9-X, the halide ligand can be coordinated
on one of the two inequivalent faces of the macrocycle,
leading to two distinct species syn and anti, shown in Scheme
6 (the slanted line shows the position of the phenolate).
A similar type of isomerism was previously observed for
some chloroiron(III) ocataethylporphyrins substituted in one
of the meso positions with AcO,54 n-Bu, OMe, or CHO.55
Selected chemical shifts and line widths for (TPBPO)-
FeIIICl, (TPBPO)FeIIIBr, and (TPBPO)FeIIII are presented in
Table 1. The line width increases in the order I- < Br- <
Cl-, similar to what is observed in high-spin iron complexes
of regular porphyrins.50-53 The signals are therefore best
resolved for the iodide complex, which was chosen for
detailed spectral analysis.51,52
The temperature dependence of the isotropic shifts re-
corded for the two isomers of (TPBPO)FeIIII (9-I) is shown
in Figure 10 (the shifts of (TPBPO)NiII have been taken as
the diamagnetic reference). The plots depart visibly from the
Curie law, and the curvature results from significant zero-
field splitting of the ground electronic state. A satisfactory
fit can be obtained, however, by including a term proportional
(50) La Mar, G. N.; Walker, A. F. NMR. The Porphyrins; Dolphin, D.,
Ed.; Academic Press: New York, 1979; Vol. IVB, pp 57-161.
(51) La Mar, G. N.; Eaton, G. R.; Holm, R. H.; Walker, F. A. J. Am. Chem.
Soc. 1973, 95, 63.
(52) Balch, A. L.; Cheng, R.-J.; La Mar, G. N.; Latos-Graz˘yn´ski, L. Inorg.
(54) Balch, A. L.; Latos-Graz˘yn´ski, L.; Noll, B. C.; Olmstead, M. M.;
Zovinka, E. P. Inorg. Chem. 1992, 31, 2248.
Chem. 1985, 24, 2651.
(53) Wojaczyn´ski, J.; Latos-Graz˘yn´ski, L.; Hrycyk, W.; Pacholska, E.;
Rachlewicz, K.; Szterenberg, L. Inorg. Chem. 1996, 35, 6861.
(55) Kalish, H.; Camp, J. E.; Ste¸pien´, M.; Latos-Graz˘yn´ski, L.; Olmstead,
M. M.; Balch, A. L. Inorg. Chem. 2002, 41, 989.
Inorganic Chemistry, Vol. 42, No. 20, 2003 6189

Ste¸pien´ and Latos-Graz3yn´ski
The spectroscopic patterns of the (TPBPO)FeIIIX isomers
(Figure 8, Table 1) are consistent with their high-spin nature.
In all cases (9-Cl,Br,I), the downfield shifts of the â-pyrrole
signals are greater for the more populated form (9b). The
isotropic shift values approach those found for high-spin iron-
(III) tetraarylporphyrins, â-substituted tetraarylporphy-
rins,49,53,59 N-methylporphyrins,60,61 and porphycene.62 The
paramagnetic shifts of high-spin iron(III) can be explained
by a model typically applied to regular iron porphyrins and
iron N-substituted porphyrins. In the case of a high-spin iron-
Scheme 6
1
2
1
1
2
2
2
(III) center, (dxy) (dxzdyz) (dz ) (dx -y ) , both σ and π routes
of spin-density delocalization operate. The domination of the
σ-route results in the downfield shifts of pyrrole resonances
observed for (TPBPO)FeIIIX.49,53,59-61,63
Each of these substituents can be oriented in two different
ways (syn or anti) with respect to the axial chloride, and
two isomers could be observed by H NMR spectroscopy.
Of particular significance is the shift pattern demonstrated
by the phenoxy moiety. Sign alternation of the 2,4- and 3-H
resonances is evident for the two isomers (Table 1). Actually,
analogous alternation was previously observed for the
phenoxide ligand axially coordinated to high-spin iron
1
Analogous structural diversity is exhibited by complexes
of N-tosylamido-meso-tetraphenylporphyrin. In a recent study
it was shown that their stereochemistry depends on the
coordinated metal ion.56 In the gallium(III) species, the axial
acetate and the N-tosylamide substituent were bound on
opposite sides of the macrocycle (the trans isomer), while
in the thallium(III) complex they were located on the same
side (cis isomer).
Other systems where the discussed kind of isomerism
could arise are complexes of N-methylporphyrin (N-MeP)H
and 21-thiaporphyrin (SP)H, where the presence of the
methyl group or the bulky sulfur atom renders the two faces
of the macrocycle inequivalent. In a series of (N-MeP)MII-
Cl and [(N-MeP)MIIICl]+ complexes, only the anti forms
were observed, most probably for steric reasons.57 Similarly,
only the anti isomers formed in the (SP)MIICl series.1
Apparently, this steric restriction is not severe and six-
coordinate complexes of N-methyl- and thiaporphyrins are
known where both sides of the macrocycle are occupied with
axial ligands.58 Finally, the trans preference is also demon-
strated by the zinc(II) complex of acetoxybenziporphyrin (6-
Zn).
1
porphyrins or iron(III) porphycene.59,62,64-66 The H NMR
pattern is very characteristic for phenoxide coordination (e.g.,
(TPP)FeOPh ortho, -118.4; meta, 95; para, -109.7 ppm at
295 K) and was accounted for by π delocalization on the
PhO moiety.59,65 There is a σ donation from the oxygen
orbital of axially coordinated phenoxide into the half
2
occupied dz orbital of high-spin iron(III). Consequently, it
creates a significant amount of spin density on the oxygen
orbitals involved in formation of the Fe-O bond. The overlap
between oxygen orbitals and the pz orbital of the ipso carbon
provides a route to π spin delocalization onto the phenoxy
ligand. An identical mechanism is instrumental in the
investigated case of (TPBPO)FeIIII, although, because of the
location of the phenoxy group in the meridional plane, the
2
2
2
half-occupied dx -y orbital, instead of dz , is included in the
discussed delocalization route.
In the three complexes 9-X (X ) Cl, Br, I), the less-
populated form is always characterized by a wider spread
of the 2,4-H and 3-H resonances. For instance, for the iodide
species, the 2,4-H signal of the minor isomer is displaced
downfield by 30 ppm compared to the major form. The effect
is even stronger for the 3-H resonance, which is shifted
upfield by an additional 119 ppm. This indicates that the
overlap between the π system of the phenoxy unit and the d
orbitals of the iron differs substantially between the two
isomers. Arguably, an additional spin delocalization pathway
may be operative, resulting from a direct overlap between
the d orbitals on the metal center and the π orbitals on the
It is impossible to distinguish the syn and anti forms in
the NMR spectra of 9-X on the basis of chemical shifts
alone. Judging by the geometry of the palladium species (6-
Pd), the two faces of the macrocycle in 9-X should be
similarly accessible to the axial ligand and the preference
for one of the isomers may be determined by the overall
conformation of the macrocyclic ligand or other, more subtle
effects.
When the halide anion is replaced by the noncoordinating
-
BF4 to produce 9-BF4 (Scheme 6), the source of iso-
(59) Arasasingham, R. D.; Balch, A. L.; Hart, R. H.; Latos-Graz˘yn´ski, L.
J. Am. Chem. Soc. 1990, 112, 7566.
meric differentiation is removed. Coordination of solvent
molecules is still possible (MeOH-d4 used in the experiment)
and may yield similar spectroscopic pattern as in the case
of 9-X.
(60) Balch, A. L.; La Mar, G. N.; Latos-Graz˘yn´ski, L.; Renner, M. W.
Inorg. Chem. 1985, 24, 2432.
(61) Balch, A. L.; Cornman, C. R.; Latos-Graz˘yn´ski, L.; Olmstead, M. M.
J. Am. Chem. Soc. 1990, 112, 7552.
(62) Rachlewicz, K.; Latos-Graz˘yn´ski, L.; Vogel, E.; Ciunik, Z.; Jerzy-
kiewicz, L. Inorg. Chem. 2002, 41, 1979.
(56) Tung, J.-Y.; Jiang, J.-I.; Lin, C.-C.; Chen, J.-H.; Hwang, L.-P. Inorg.
Chem. 2000, 39, 1.
(57) Lavallee, D. K. The Chemistry and Biochemistry of N-Substituted
Porphyrins; VCH Publishers Inc.: New York, 1987.
(58) Latos-Graz˘yn´ski, L.; Lisowski, J.; Olmstead, M. M.; Balch, A. L. Inorg.
Chem. 1989, 28, 3328.
(63) Pawlicki, M.; Latos-Graz˘yn´ski, L. Inorg. Chem. 2002, 41, 5866.
(64) Godziela, G. M.; Tilotta, D.; Goff, H. M. Inorg. Chem. 1986, 25, 2142.
(65) Balch, A. L.; Hart, R. H.; Latos-Graz˘yn´ski, L. Inorg. Chem. 1990,
29, 3253.
(66) Arasasingham, R. D.; Balch, A. L.; Cornman, C. R.; de Ropp, J. S.;
Eguchi, K.; La Mar, G. N. Inorg. Chem. 1990, 29, 1847.
6190 Inorganic Chemistry, Vol. 42, No. 20, 2003

Core-Modified Porphyrin Incorporting Phenolate Donor
(CD2Cl2, 233 K): 7.8-7.5 (m, 10H, 6,11,16,21-Ph); 12.12, 7.61,
ipso carbon, C(22). This effect would heavily depend on the
Fe‚‚‚C(22) distance, which presumably differs between the
two isomers. As noted before, this distance is small in
complex 6-Pd (2.57 Å).
4
6.90 (ABC: 23,25-H, 8,19-H, 9,18-H, 3JBC ) 5.0 Hz, 4JAB ≈ JAC
≈ 1 Hz); 9.43 (s, 1H, 22-OH); 8.04, 7.27 (AB2: 24-H, 13,14-H,
3
4JAB ≈ 1 Hz); 7.24, 6.69 (AB2: 3-H, 2,4-H, JAB ) 7.6 Hz). 13C
NMR (CD2Cl2, 233 K): 158.6 (10,17-C); 150.8 (12,15-C); 149.1
(6,21-Ph); 144.5 (7,20-C); 140.1 (ipso-Ph); 138.0 (2,4-C); 137.6
(8,19-C); 136.8 (ipso-Ph, no correlations found); 135.8 (o/m-Ph);
133.9 (o/m/p-Ph); 133.3 (o/m/p-Ph); 133.3 (13,14-C); 131.9 (m-
Ph); 130.5 (1,5-C); 129.6 (o/m/p-Ph); 128.4 (o/m-Ph); 128.2 (o/m-
Ph); 128.1 (9,18-C); 127.0 (3-C); 115.5 (11,16-C); 113.3 (22-C).
UV-vis (CH2Cl2, λmax [nm] (log ꢀ)): 327 (4.52); 388 (4.43); 471
(5.07); 920 (4.09, broad). HRMS (ESI, m/z): 642.2559 (642.2540
for C46H32N3O+).
Conclusion
Two distinct types of metal complexes have been obtained
from 22-acetoxybenziporphyrin (4). In the species 8-M (M
) Zn, Cd), the acetoxyl substituent is left intact and the metal
ion is coordinated to the three nitrogens of the macrocyclic
core. In the other group of complexes, exemplified by 6-M
(M ) Ni, Pd) and the ferric species 9-X, the Ac-O bond
is cleaved, and the phenolic oxygen participates in binding
the metal ion. In the latter case, acetoxybenziporphyrin offers
a convenient shortcut to complexes of 22-hydroxybenzipor-
phyrin, making prior hydrolysis of the ester bond unneces-
sary.
The type of complex that is obtained depends on the metal
ion, namely, on its ability to break the ester bond. For
instance, (TPBPO)ZnII (6-Zn) cannot be synthesized directly
from acetoxybenziporphyrin, and [5-H2]Cl2 has to be used
as the ligand source. Conversely, Ni(II) insertion to acetoxy-
benziporphyrin quickly yields (TPBPO)NiII (6-Ni), and
(TPBPOAc)NiIICl (8-Ni) is observed only as a transient
species. 8-Ni can be synthesized in a reaction of 6-Ni with
acetyl chloride.
The nonplanarity of the macrocycle in the complexes
(TPBPO)FeIIIX (9-X) gives rise to a type of positional
isomerism. Ligand X and the deflected m-phenylene ring may
lie on the same side of the macrocycle or on the opposite
sides, leading to two distinct species (syn and anti, respec-
tively).
In complexes 6-M and 9-X, the M-O-C angle lies in
a plane perpendicular to the phenoxide moiety. This unusual
arrangement is a consequence of restraints imposed by the
ligand structure, which lead to significant compression of
the M-O-C angle.
Chlorozinc(II) 6,11,16,21-Tetraphenyl-22-acetoxy-m-benzi-
porphyrin (8-Zn). Acetoxybenziporphyrin (4, 20 mg) and anhy-
drous zinc(II) chloride (molar excess) are added to acetonitrile (15
mL) and refluxed under nitrogen for 15 min. The color of the
solution changes from blue-green to yellow-brown. The reaction
mixture is then cooled and diluted with water (the solution becomes
green). The compound is extracted with dichloromethane, and the
extracts are dried with anhydrous sodium sulfate and evaporated
to dryness. The residue contains practically pure chlorozinc
1
complex. H NMR (CDCl3, 298 K): 7.65-7.60, 7.54-7.43 (m,
10H, 6,11,16,21-Ph); 7.54, 6.86 (AB: 8,19-H, 9,18-H, 3JAB ) 5.1
3
Hz); 7.41, 7.15 (AB2: 3-H, 2,4-H, JAB ) 7.7 Hz); 7.13 (s, 2H,
13,14-H); 1.14 (s, 3H, Me). 13C NMR (CDCl3, 298 K): 168.1 (CO);
168.0 (10,17-C); 160.6 (12,15-C); 152.9 (7,20-C); 141.6 (6,21-ipso-
Ph); 139.7 (11,16-ipso-Ph); 137.3 (6,21-C); 135.4 (8,19-C); 134.3
(13,14-C); 134.1 (o-Ph); 133.3 (1,5-C); 132.7 (o/m-Ph); 131.9 (9,-
18-C); 131.6 (2,4-C); 129.5 (3-C); 129.0 (o/m/p-Ph); 127.8, 127.7,
127.6 (o/m/p-Ph); 116.8 (11,16-C); 102.8 (22-C); 20.1 (Me). UV-
vis (CH2Cl2, λmax [nm] (log ꢀ)): 428 (4.92); 567 (3.39); 820 (4.48).
HRMS (ESI, m/z): 746.1798 (746.1780 for C48H32N3O2Zn+).
Chlorocadmium(II) 6,11,16,21-Tetraphenyl-22-acetoxy-m-
benziporphyrin (8-Cd). Acetoxybenziporphyrin (4, 20 mg) and
anhydrous cadmium(II) chloride67 (molar excess) are added to a
mixture of chloroform and acetonitrile (10 + 10 mL) and refluxed
under nitrogen for 30 min. The yellow-brown solution is then
evaporated to dryness, redissolved in a small volume of dichlo-
romethane, and filtered through a Teflon disk. The solvent is
removed and the chlorocadmium complex is obtained quantitatively.
1H NMR (CDCl3, 298 K): 7.62-7.59, 7.53-7.42 (m, 10H, 6,11,-
16,21-Ph); 7.50, 6.78 (AB: 8,19-H, 9,18-H, 3JAB ) 5.0 Hz); 7.48,
Further investigations of the hydroxybenziporphyrin com-
plexes may afford an insight into the redox properties of
phenols in the presence of metal ions. The macrocyclic
structure of the ligand may be expected to stabilize inter-
mediates as well as the frequently elusive products of such
reactivity.
3
7.26 (AB2: 3-H, 2,4-H, JAB ) 7.7 Hz); 7.11 (s, 2H, 13,14-H);
1.26 (s, 3H, Me). 13C NMR (CDCl3, 298 K): 169.0 (10,17-C); 168.8
(CO); 162.8 (12,15-C); 153.0 (7,20-C); 141.3 (ipso-Ph); 140.1 (ipso-
Ph); 135.4 (6,21-C); 135.0 (13,14-C); 134.6 (8,19-C); 133.9 (o-
Ph, may overlap with 1,5-C); 133.3 (9,18-C, may overlap with 1,5-
C); 132.8 (o/m-Ph); 131.9 (2,4-C); 130.7 (3-C); 129.2, 128.0, 127.8,
127.5 (o/m/p-Ph); 117.5 (11,16-C); 102.7 (22-C); 20.1 (Me).
Experimental Section
Dichloromethane and acetonitrile were distilled from calcium
hydride prior to use. Nickel(II) chloride was dried at 120 °C until
yellow. Dilute hydriodic acid was treated with small portions of
solid NaBH4 until the disappearance of dissolved iodine.
6,11,16,21-Tetraphenyl-22-acetoxy-m-benziporphyrin (4) was
obtained as previously described.7
6,11,16,21-Tetraphenyl-22-hydroxy-m-benziporphyrin Dica-
tion Dichloride, [5-H2]Cl2. Acetoxybenziporphyrin (4, 23.5 mg)
is dissolved in chloroform (10 mL) and refluxed with concentrated
hydrochloric acid (10 mL) for 2 h. Afterward, the organic layer is
withdrawn with a pipet, washed once with water, dried with
anhydrous calcium chloride, and filtered. The solution is concen-
trated and the dication precipitated with n-hexane. The compound
slowly loses HCl upon standing. Yield: 18.0 mg (73%). 1H NMR
Palladium(II) 6,11,16,21-Tetraphenyl-22-hydroxy-m-benzi-
porphyrin (6-Pd). Acetoxybenziporphyrin (4, 9.1 mg, 13.3 µmol)
and palladium(II) chloride (3.2 mg, 18 µmol) are refluxed in
acetonitrile (15 mL) under nitrogen. After 4 h, the reaction mixture
is evaporated to dryness, and the product is recrystallized from
dichloromethane/hexane. Yield: 6.7 mg (67%). 1H NMR (CDCl3,
298 K): 7.34-7.43 (m, 10H, 6,11,16,21-Ph); 7.09, 6.45 (AB: 8,-
3
19-H, 9,18-H, JAB ) 5.3 Hz); 6.68 (s, 2H, 13,14-H); 6.51, 6.01
3
(AB2: 3-H, 2,4-H, JAB ) 7.7 Hz). 13C NMR (CDCl3, 298 K):
160.5 (10,17-C); 154.9 (12,15-C); 152.7 (7,20-C); 147.2 (6,21-C);
(67) Handbook of PreparatiVe Inorganic Chemistry, 2nd ed.; Bauer, G.,
Ed.; Acadamic Press: New York, London, 1963.
Inorganic Chemistry, Vol. 42, No. 20, 2003 6191

Ste¸pien´ and Latos-Graz3yn´ski
Table 2. Crystal Structure Data for 6-Pd, 6-Pd‚TFA, and 8-Zn
6-Pd‚CDCl3
6-Pd‚TFA‚2CDCl3
8-Zn‚2CD2Cl2
cryst grown by
slow evaporation of a CDCl3 solution
dark prism
C47H29DCl3N3OPd
865.5
slow evaporation of a CDCl3 solution
dark prism
C50H29D2Cl6F3N3O3Pd
1099.9
slow evaporation of a CD2Cl2 solution
dark irregular block, violet luster
C50H32D4Cl5N3O2Zn
957.4
cryst habit
formula
fw
a, Å
b, Å
c, Å
15.0961(7)
14.6038(9)
16.7035(9)
14.9805(9)
13.8084(7)
22.1604(10)
10.0525(5)
17.7456(8)
12.3798(7)
R, °
â, °
93.027(4)
100.337(5)
102.527(5)
γ, °
V, Å3
Z
3677.3(3)
4
1.563
monoclinic
P21/n
4509.6(4)
4
1.617
monoclinic
P21/c
2155.83(19)
2
1.469
monoclinic
P21/m
D
calc, g‚cm-3
cryst syst
space group
cryst size, mm
µ, mm-1
0.3 × 0.5 × 0.5
0.2 × 0.2 × 0.4
0.4 × 0.6 × 0.6
0.766
0.828
0.925
absorption correction
Tmin, Tmax
T, K
psi-scan (ellipsoid)
0.736, 0.843
100 (2)
psi-scan (ellipsoid)
0.636, 0.707
100 (2)
psi-scan (ellipsoid)
0.341, 0.402
100 (2)
θ range
3.71 e θ e 28.38
-19 e h e 20
-19 e k e 16
-21 e l e 21
8543
3.26 e θ e 28.48
-19 e h e 17
-18 e k e 18
-28 e l e 29
10560
3.37 e θ e 28.39
-13 e h e 13
-22 e k e 19
-16 e l e 15
5146
hkl range
reflns measd
unique reflns, I g 2 σ(I)
parameters/restraints
7571
629/6
8664
667/3
4753
305/0
R1
wR2
S
0.0290
0.0686
1.085
0.55/-1.02
0.0374
0.0936
1.100
1.21/-0.75
0.0649
0.1636
1.324
0.67/-0.71
F
max/Fmin, e‚Å3
142.5 (ipso-Ph); 139.0 (8,19-C); 138.6 (ipso-Ph);137.6 (2,4-C);
134.1 (13,14-C); 132.9, 132.0, 131.7 (o/m/p-Ph); 131.0 (1,5-C);
128.0, 127.9, 127.6, 126.9 (o/m/p-Ph); 126.7 (22-C); 125.3 (9,18-
C); 121.7 (3-C); 115.8 (11,16-C). UV-vis (CH2Cl2, λmax [nm] (log
ꢀ)): 349 (4.41); 396 (4.58); 437 (4.58); 607 (4.11); 873 (3.50).
HRMS (ESI, m/z): 746.1459 (746.1418 for C46H30N3O106Pd+).
Iodoiron(III) 6,11,16,21-Tetraphenyl-22-hydroxy-m-benzipor-
phyrin (9-I). The chloroiron(III) complex 9-Cl is dissolved in a
small volume of chloroform and stirred with hydriodic acid
(concentrated stock solution diluted with water in 1:10 ratio) for 1
h (progress of the axial ligand exchange was monitored by 1H NMR
spectroscopy). UV-vis (CH2Cl2, λmax [nm] (log ꢀ)): 302 (4.47);
348 (4.41); 424 (4.44); 718 (3.50); 931 (3.30). The bromoiron(III)
species (9-Br) was obtained analogously using aqueous HBr.
Nickel(II) 6,11,16,21-tetraphenyl-22-hydroxy-m-benziporphy-
rin (6-Ni) is prepared analogously to the palladium species using
1 equiv (or slight excess) of anhydrous nickel(II) chloride.
Alternatively, [5-H2]Cl2 (12.4 mg, 17 mmol) is refluxed in MeCN
with NiCl2 (5 mg, 38 mmol) for 5 h. The solution is then evaporated,
redissolved in CH2Cl2, filtered through a Teflon disk, and crystal-
lized from CH2Cl2/n-hexane to afford the nickel(II) complex 6-Ni
Instrumentation. NMR spectra were recorded on a Bruker
Avance 500 spectrometer (base frequencies 1H, 500.13 MHz; 13C,
125.77 MHz) equipped with a broadband inverse gradient probe-
1
head, a dual H-13C gradient probehead, or a direct broadband
probehead. Spectra were referenced to the residual solvent signals.
Except for NOESY spectra, all 2D experiments were gradient
selected. The DPFGSE experiment was performed using pulse
program selnogp.3 from the standard Bruker library. Gaussian
pulses were employed with a duration of 50 ms. Assignments of
13C spectra were obtained from 1H-13C HSQC and HMBC
experiments.
1
(9 mg, 74%). H NMR (CDCl3, 298 K): 7.40-7.24 (m, 10H, 6,-
3
11,16,21-Ph); 7.01, 6.33 (AB: 8,19-H, 9,18-H, JAB ) 5.3 Hz);
3
6.68 (s, 2H, 13,14-H); 6.68, 6.23 (AB2: 3-H, 2,4-H, JAB ) 7.7
Hz). 13C NMR (CDCl3, 298 K): 163.1 (10,17-C); 156.6 (12,15-
C); 155.2 (7,20-C); 144.3 (6,21-C); 142.3 (11,16-ipso-Ph); 140.1
(8,19-C); 138.3 (6,21-ipso-Ph, no correlations found); 137.4 (2,4-
C); 134.3 (13,14-C); 133.3 (1,5-C); 132.6 (o-Ph); 132.0, 131.5
(broad, o/m/p-Ph); 129.8 (22-C); 127.9, 127.5, 126.8 (o/m/p-Ph);
125.9 (9,18-C); 121.3 (3-C); 115.1 (11,16-C). UV-vis (CH2Cl2,
X-ray Data Collection and Refinement. Crystals of 6-Pd,
6-Pd‚TFA, and 8-Zn were grown by slow evaporation of CDCl3
or CD2Cl2 solutions. Crystal data and refinement details are given
in Table 2. The data were collected on a Kuma KM4CCD κ-axis
diffractometer with graphite-monochromated Mo KR radiation and
processed using the accompanying software. The structures were
solved by heavy-atom or direct methods (SHELXS97 68) and refined
by the full-matrix least-squares method on all F2 data using the
SHELXL97 program.69 Hydrogen atoms were found in the differ-
ence map and refined isotropically (6-Pd) or as riding groups (6-
λmax [nm] (log ꢀ)): 329 (4.44); 368 (4.54); 439 (4.68); 637 (3.61);
890 (3.51). HRMS (ESI, m/z): 697.1648 (697.1659 for C46H29N3-
ONi+).
Chloroiron(III) 6,11,16,21-Tetraphenyl-22-hydroxy-m-ben-
ziporphyrin (9-Cl). Acetoxybenziporphyrin (4, 15.7 mg, 23 mmol)
and anhydrous iron(II) chloride (10 mg, 79 mmol) are refluxed in
acetonitrile (25 mL) for 3 h. The reaction mixture is poured into
50 mL of water, and the complex is extracted with dichloromethane.
The extracts are dried with anhydrous sodium sulfate and filtered,
and the solvent is removed. The residue is crystallized from CH2-
Cl2-MeOH to give the chloroiron(III) species 9-Cl (13.5 mg,
80%). HRMS (ESI, m/z): 695.1674 (695.1655 for C46H29N3OFe+).
(68) Sheldrick, G. M. SHELXS97 - Program for Crystal Structure Solution.
University of Go¨ttingen: Go¨ttingen, Germany, 1997.
(69) Sheldrick, G. M. SHELXL97 - Program for Crystal Structure
Refinement. University of Go¨ttingen: Go¨ttingen, Germany, 1997.
6192 Inorganic Chemistry, Vol. 42, No. 20, 2003

Core-Modified Porphyrin Incorporting Phenolate Donor
Pd‚TFA and 8-Zn). Psi-scan absorption correction was applied.70
The disordered CDCl3 molecule in 6-Pd was refined in two
orientations with a total unit occupancy. In the remaining structures,
the disorder of solvent molecules, as well as that of CH3 and CF3
groups, was handled similarly.
T09A 147 22) and the Foundation for Polish Science is
kindly acknowledged.
Supporting Information Available: Crystal data for com-
pounds 6-Pd, 6-Pd‚TFA, and 8-Zn are included in CIF format.
The material is available free of charge via the Internet at
http://pubs.acs.org.
Acknowledgment. Financial support from the State
Committee for Scientific Research KBN of Poland (Grant 4
(70) XPREP Data Preparation and Reciprocal Space Exploration Program.
IC0345121
Bruker Analytical X-ray Systems: 1997.
Inorganic Chemistry, Vol. 42, No. 20, 2003 6193