Perhalogenated porphyrinic derivatives with indium and thallium: The X-ray structures of (β-Cl4TPP)Tl(Cl), (β-Cl4TPP)In(Cl) and (TpFTPP)Tl(Cl)

Article abstract of DOI:10.1016/j.poly.2004.04.010

The synthesis and spectroscopic characterization of new substituted porphyrinate complexes are reported. The investigated compounds are represented by the formula (Porph)M(Cl) where Porph are TpFPP, TPyP, β-Cl ₄TPP, β-Cl₈TPP or β-Cl₄TPP, and M=In or Tl. UV-Vis and NMR spectroscopies of the title complexes confirm the proposed molecular formula and are described extracting all plausible information. The study is completed by three X-ray structures of (β-Cl₄TPP)Tl(Cl) , (β-Cl₄TPP)In(Cl) and (TpFTPP)Tl(Cl). Compounds (β-Cl ₄TPP)Tl(Cl) and (β-Cl₄TPP)In(Cl) are isostructural and they were treated in a similar way. The chloride substituents on the porphyrin core were found to be disordered in both compounds and they were refined anisotropically with occupation factors free to vary. The porphyrin core is saddle distorted while there is no twist distortion as judged by the large values of the dihedral angles formed between the phenyl rings and the C ₂₀N₄ mean plane. In compound (TpFTPP)In(Cl), the dihedral angles between the pentafluorophenyl rings and C₂₀N₄ are very close to the ideal value of 90°.

Full text of DOI:10.1016/j.poly.2004.04.010

Polyhedron 23 (2004) 1777–1784
www.elsevier.com/locate/poly
Perhalogenated porphyrinic derivatives with indium and thallium:
the X-ray structures of (b-Cl4TPP)Tl(Cl), (b-Cl4TPP)In(Cl)
and (TpFTPP)Tl(Cl) q
a
Catherina Raptopoulou , Dimitra Daphnomili , Athanassios Karamalides ,
b
c
c
Massimo Di Vaira , Aris Terzis , Athanassios G. Coutsolelos
a
b,
*
a
NCRS, Demokritos, Agia Paraskevi, 15310 Athens, Greece
b
Laboratory of Bioinorganic Coordination Chemistry, Department of Chemistry, School of Sciences, University of Crete,
P.O. Box 1470, 71409 Heraklion Crete, Greece
c
Universita degli Studi di Firenze, Dipartimento di Chimica, Via della Lastruccia 5, Sesto Fiorentino, Firenze, Italy
Received 10 November 2003; accepted 24 March 2004
Available online 10 May 2004
Abstract
The synthesis and spectroscopic characterization of new substituted porphyrinate complexes are reported. The investigated
compounds are represented by the formula (Porph)M(Cl) where Porph are TpFPP, TPyP, b-Cl4TPP, b-Cl8TPP or b-Cl4TPP, and
M ¼ In or Tl.
UV–Vis and NMR spectroscopies of the title complexes confirm the proposed molecular formula and are described extracting all
plausible information. The study is completed by three X-ray structures of (b-Cl4TPP)Tl(Cl), (b-Cl4TPP)In(Cl) and
(TpFTPP)Tl(Cl).
Compounds (b-Cl4TPP)Tl(Cl) and (b-Cl4TPP)In(Cl) are isostructural and they were treated in a similar way. The chloride
substituents on the porphyrin core were found to be disordered in both compounds and they were refined anisotropically with
occupation factors free to vary. The porphyrin core is saddle distorted while there is no twist distortion as judged by the large values
of the dihedral angles formed between the phenyl rings and the C20N4 mean plane. In compound (TpFTPP)In(Cl), the dihedral
angles between the pentafluorophenyl rings and C20N4 are very close to the ideal value of 90°.
Ó 2004 Elsevier Ltd. All rights reserved.
Keywords: Metalloporphyrins; Indium; Thallium
1. Introduction
chemical properties. Investigations have been carried
out to probe the electronic structures of these systems by
different approaches involving spectral and redox po-
tential data as well as semi-empirical calculations. For b-
halogenated porphyrins with more than four halogens,
the electronic effects of the peripheral substituents cau-
ses a decrease of the basicity of the porphyrin ring, a red
shift of the Soret band transition energy and a decrease
in HOMO–LUMO energy gap [10–18].
Porphyrin complexes of the main group IIIB are ideal
model compounds since they show considerable flexi-
bility of the core geometries depending on the peripheral
substitution and on axial ligation [1–9].
Meso-substitution as well as b-halogenation on the
porphyrin core is expected to alter their spectroelectro-
Metal ions incorporated into perhalogenated com-
plexes are mainly copper, zinc and nickel [10,12,14,16–
18] as far as concerns the four coordinated ions, while
iron complexes have also been reported due to the en-
hanced catalytic activity of these systems [11,18,19].
q Supplementary data associated with this article can be found, in the
online version, at doi:10.1016/j.poly.2004.04.010.
* Corresponding author. Tel.: +30-2810-393636; fax: +30-2810-
393601.
E-mail address: coutsole@chemistry.uoc.gr (A.G. Coutsolelos).
0277-5387/$ - see front matter Ó 2004 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2004.04.010

1778
C. Raptopoulou et al. / Polyhedron 23 (2004) 1777–1784
Recently the X-ray study of a lanthanide perhalogen-
ated complex has been published [14]. It has been sug-
gested that the metal ion and its environment influence
the redox potential of these systems.
(TPyP)TlCl (2): The same reaction process as men-
tioned above was followed. The product was recovered
after recrystallization from a mixture of CH2Cl2/C6H14
(1/3 v/v), (yield: 94%).
Based on a recently published procedure [14] we
achieved the synthesis of halogenated In(III) and Tl(III)
complexes. Their physicochemical features are com-
pared with those of meso-substituted derivatives. Met-
allation with In or Tl offers a unique probe to study the
influence of peripheral substituents and/or of the central
metal on their physicochemical properties. A work
correlating the 205Tl NMR chemical shifts to the basicity
of the ring, the axial ligation and the oxidation state has
already been published by our group [20]. Monomeric
thallium complexes provide 205Tl signals from approxi-
mately 2850–2700 ppm following a decreasing order of
basicity, while in the case of dimeric complexes (with a
Rh:!Tl metal bond, typical +1 oxidation state of Tl)
the signal is shifted more than 2000 ppm to the region of
180–200 ppm [21].
(b-Cl4TPP)TlCl (3): The reaction was performed as
for compound 1. A column of SiO2 (4 cm ꢀ 3 cm) was
used for the chromatographic separation. The desired
product was eluted with CH3OH/CH2Cl2 (50/50 v/v-20/
80 v/v) as eluents, (yield: 65%).
(b-Br4TPP)TlCl (4): The preparation of the crude
product was the same as described above. The column
separation was performed on SiO2 (4 cm ꢀ 3 cm). The
desired metalloporphyrin derivative was eluted with
CH2Cl2, (yield: 67%).
(b-Cl8TPP)TlCl (5): The reaction conditions men-
tioned before were also followed for the synthesis of the
crude product 5. The chromatographic separation was
performed on SiO2 column (6 cm ꢀ 4 cm). The product
was eluted with toluene/hexane (8/2 v/v), (yield: 60%).
Finally, part of our research interest is the formation
of single metal–metal bonded porphyrinic complexes.
Monomeric metalloporphyrins of In or Tl are excellent
precursors for the synthesis of new metal–metal bonded
dimers. The nature of the monomeric complexes is ex-
pected to influence dramatically the properties of the
formed dimers.
2.2.2. Syntheses of (Porph)In–Cl complexes
(TpFPP)InCl (6): 0.15 mmol of (TpFPP)H2, 1.5 mmol
of InCl3 and 16 mmol of CH3COONa were dissolved in
50 ml of glacial acetic acid. The reaction mixture was
refluxed for 24 h. The solvent was removed under re-
duced pressure and the solid residue was dissolved in
CH2Cl2. The solution was extracted from an aqueous
solution of NaHCO3 (5% w/v). The organic phase was
washed two times with a saturated aqueous solution of
NaCl and dried over MgSO4. The solvent was removed
and the solid residue was purified. A chromatographic
separation was performed on SiO2 (6 cm ꢀ 3 cm). With
CH2Cl2/hexane (4/6 v/v) the free base was eluted. In-
creasing gradually the polarity of the solvents to
CH2Cl2/hexane (8/2 v/v) the metalloporphyrin was
eluted, (yield: 85%).
(TPyP)InCl (7): The previous synthetic route was also
performed for compound 7. Basic Al2O3 (5 cm ꢀ 3 cm)
(Grade 1) was used in order to perform the chromato-
graphic separation. With CH2Cl2/MeOH (200/5 v/v) the
desired product was collected, (yield: 87%).
(b-Cl4TPP)InCl (8): The preparation followed the
previously described method for complex 6. The chro-
matographic separation was performed on basic Al2O3
(5 cm ꢀ 3 cm) (Grade 1). The metalloporphyrin was
eluted with a mixture of CH2Cl2/MeOH (7/3 v/v), (yield:
70%).
2. Experimental
2.1. Materials
All chemical were reagent grade and were used
without further purification except as noted. Basic type I
alumina was activated at 150 °C for at least 24 h.
2.2. Syntheses
The synthesis of free bases followed previously pub-
lished procedures [14,22]. The preparation of thal-
lium(III) complexes was based on Abraham’s method
[23]. The preparation of In complexes was based on the
‘‘acetate method’’ [24].
2.2.1. Syntheses of (Porph)Tl–Cl complexes
(TpFPP)TlCl (1): 0.1 mmol of (TpFPP)H2 and 1
mmol of TlIII(CH3COO)3 ꢀ 11/2H2O were dissolved in
100 ml THF. The reaction mixture was refluxed for 24 h.
After cooling, THF was removed and the solid residue
was dissolved in CH2Cl2 and washed with a saturated
aqueous solution of NaCl. Chromatographic separation
of the crude product was performed on a SiO2 column (4
cm ꢀ 3 cm). The metallated product was eluted with
CH2Cl2/C6H14 (4/6 v/v) as eluents (yield: 60%).
(b-Br4TPP)InCl (9): The preparation was the same as
described above. The crude product was chromato-
graphed on SiO2 (5 cm ꢀ 4 cm). The elution of the
metallated porphyrin was achieved with toluene, (yield:
60%).
(b-Cl8TPP)InCl (10): The reaction conditions were
the same but with THF as reaction solvent due to low
solubility of (b-Cl8TPP)H2 in the glacial acetic acid. The
chromatographic separation was achieved on SiO2 (6

C. Raptopoulou et al. / Polyhedron 23 (2004) 1777–1784
1779
cm ꢀ 4 cm) and the product was eluted with CH2Cl2;
centred reflections in the range 1° < 2h < 23°. Intensity
data were recorded using h ꢁ 2h scans. Three standard
reflections were monitored every 97 reflections over the
course of data collection and showed less than 3% var-
iation and no decay. Lorentz polarization and w-scan
absorption corrections were applied using Crystal Logic
software. The structures of 3 and 8 were solved by direct
methods using SHELXS-86 [25] and refined by full-ma-
trix least-squares techniques on F 2 with SHELXL-93 [26].
A single crystal of 6, with approximate dimensions
0.20 ꢀ 0.40 ꢀ 0.60 mm, was mounted in air on a Sie-
mens-Bruker P4 diffractometer equipped with a rotating
anode generator, graphite-monochromated Cu Ka ra-
diation being used for all operations. Cell dimensions
were determined from the angular settings of 30 reflec-
tions with 32° < h < 55°. Intensity data were recorded
by x–2h scans and three standards monitored every 90
min revealed an overall 14% intensity decay, which was
accounted for at data reduction time. A w-scan ab-
sorption correction was applied. Structure solution and
refinement were performed with SHELX [25,26].
(yield: 70%).
3. Instrumentation and methods
1H NMR and 13C NMR spectra were recorded on a
Bruker AMX-500 MHz NMR spectrometer using
chloroform-D3 as a solvent. Resonances in the 1H NMR
were referenced versus the residual proton signal of the
solvent.
Absorption spectra were collected on a Perkin–Elmer
Lamda 6 grating spectrophotometer.
Crystals suitable for X-ray diffraction were obtained
by slow evaporation of a saturated toluene solution for
compounds 3 and 8 and of a saturated solution of a
mixture of 1:1 CHCl3/toluene for compound 6.
3.1. Data collection and X-ray crystal structure determi-
nation
A
single crystal with approximate dimensions
A summary of crystallographic data for 3, 6 and 8 is
given in Table 1.
0.20 ꢀ 0.20 ꢀ 0.50 mm for 3, and 0.10 ꢀ 0.10 ꢀ 0.30 mm
for 8 were mounted in air. Diffraction measurements for
3 and 8 were made on a Crystal Logic Dual Goniometer
diffractometer using graphite monochromated Mo Ka
radiation. Unit cell dimensions were determined and
refined by using the angular settings of 25 automatically
Compounds 3 and 8 are isostructural and they were
treated in a similar way. The chloride substituents on the
porphyrin core were found disordered in both 3 and 8
and they were refined anisotropically with occupation
factors free to vary. The chlorine substitution on the
Table 1
Summary of crystal, intensity collection and refinement data for compounds (b-Cl4TPP)TlCl (3), (TpFPP)InCl (6) and (b-Cl4TPP)InCl (8)
Parameters
(3) ꢂ C6H5CH3
51H32Cl5N4Tl
(8) ꢂ C6H5CH3
C51H32Cl5InN4
(6) ꢂ 1.5(C6H6)
C53H17ClF20InN4
1239.98
Formula
Fw
C
1082.43
triclinic
992.88
triclinic
Crystal system
Space group
Temperature (K)
Unit cell dimensions
monoclinic
P21=n
298
ꢀ
ꢀ
P1
298
P1
298
ꢁ
a (A)
13.942(6)
14.284(6)
13.368(6)
105.32(1)
118.44(1)
90.39(1)
13.914(6)
14.198(7)
13.238(6)
104.73(1)
118.02(1)
91.10(1)
14.775(3)
12.979(2)
26.222(6)
–
ꢁ
b (A)
ꢁ
c (A)
a (°)
b (°)
c (°)
92.66(2)
–
5023(2)
3
ꢁ
V (A )
2230(2)
2
2203(2)
2
Z
4
qcalcd (g cmꢁ3
Radiation, h (A)
l (mmꢁ1
)
1.612/1.60
Mo Ka 0.71073
3.962
1.497/1.48
Mo Ka 0.71073
0.881
1.640/1.63
Cu Ka 1.5418
5.309
ꢁ
)
Reflections collected/unique [Rint
Data with I > 2rðIÞ
]
7783/7428 [0.0156]
6340
561
6412/6110 [0.0237]
4345
562
9238/5827 [0.0388]
5618
758
Parameters refined
ꢁ3
ꢁ
ðDqÞmax, ðDqÞ (e A
min
)
0.696/)0.794
a ¼ 0:0657, b ¼ 1:2315
1.179
0.705/)0.521
a ¼ 0:0703, b ¼ 9:0137
1.014
1.998/)0.715
a ¼ 0:0921, b ¼ 9:6349
1.134
wa
Goodness-of-fit (on F 2)
c
R1b, wR2 (all data)
0.0595, 0.1260
0.0469, 0.1184
0.1004, 0.1984
0.0680, 0.1625
0.0584, 0.1618
0.0573, 0.1606
R1b, wR2 (I > 2rðIÞ)
c
2
a w ¼ 1=½r2ðFo2Þ þ ðaPÞ þ bPꢃ and P ¼ ðmaxðFo2; 0Þ þ 2Fc2Þ=3.
P
P
b R1 ¼ ðjFoj ꢁ jFcjÞ= ðjFojÞ.
P
P
2
2
1=2
c wR2 ¼ f ½wðFo2 ꢁ Fc2Þ ꢃ= ½wðFo2Þ ꢃg
.

1780
C. Raptopoulou et al. / Polyhedron 23 (2004) 1777–1784
pyrroles of the porphyrin skeleton is unsymmetrical in
both 3 and 8. The distribution of the chloride ions is
unsymmetrical because there are two pyrrole rings,
which are monosubstituted, one that is doubly substi-
tuted and one unsubstituted. In compound 3, there is
64% probability of the presence of chlorine substituents
in C2, C7, C12, C13 and 36% probability of the presence
of the substituents in the remaining Cb atoms of the
porphyrin. The corresponding probabilities in com-
pound 8 are 60% in C2, C7, C12, C13 and 40% in the
remaining Cb positions. In both 3 and 8, all the non-
hydrogen atoms were refined anisotropically, except
those of the toluene solvent molecule, which were re-
fined isotropically. The toluene molecule was found
disordered over two orientations and was refined with
occupation factors of a total sum of one. All H atoms
were introduced at calculated positions as riding on
bonded atoms; no H atoms for the toluene solvent
molecule were included in the refinement.
In the model for the structure of 6 all the non-hy-
drogen atoms were refined anisotropically and the hy-
drogen atoms, both of the TPP ring and of the solvent
molecules, were in calculated positions, riding. Presence
of solvate molecules in the structure was modelled by
two benzene molecules: one was distributed over two
orientations whose complementary occupancy factors
were refined and the other one, lying in proximity of an
inversion centre, was assigned a fixed 0.50 occupancy
factor value.
halogenated complexes (Table 2). In the case of Tl
complexes a scalar coupling of pyrrolic protons with the
Tl nucleus is observed, which is measured close to 75 Hz.
Taking advantage of the 100% natural abundance of
spin 1/2 19F and its high gyromagnetic ratio, 19F NMR
experiments were performed. Five separate signals were
observed (Table 3). The porphyrin ring current and the
position of the fluorine atoms related to the porphyrin
ring differentiate them. The furthest downfield signals,
which appeared as two doublets, are attributed to ortho-
F and to ortho0-F (J ¼ 23:5 Hz). The fluorine atom at
the para position appeared as a triplet. Metallation
mainly effects the chemical shifts of ortho-F, ortho0-F
and meta-F compared to the free base [27].
13C- NMR signals spread in a 200 ppm region (Table
4). Assignment was based on heteronuclear experiments
(HMQC, HMBC). We can distinguish two major groups
for carbon frequencies. The aromatic carbons resonate
between 130 and 170 ppm and the methinic carbons in
the region of 90–120 ppm. The chemical data does not
present any unexpected information in respect to other
metalloporphyrinic derivatives. However the chemical
shifts for Cph are sensitive to the number of the halogen
atoms: 140.18 ppm for (b-Cl4TPP)TlCl to 144.2 ppm for
(b-Cl8TPP)TlCl.
Cb are the most sensitive carbon atoms to substitu-
tion. For tetrahalogenated complexes Cb provide two
signals, one which is attributed to Cb-H and one to Cb-X
(X ¼ Cl, Br). In the case of (b-Cl4TPP)TlCl, Cb–Cl res-
onate at 135.34 ppm. The signal at 133.72 ppm was
assigned through heteronuclear experiments to Cb-H
and for the tetrabrominated analogue at 134.2 ppm. In
the case of octahalogenated complexes Cb–Cl is di-
shielded at 137.86 ppm for (b-Cl8TPP)TlCl.
4. Results and discussion
4.1. NMR
The title complexes are fully characterized by 1H
NMR and 13C NMR, while for the case of pentaflu-
oroporphyrins 19F NMR experiments were performed.
By the performance of 1H NMR we observed the
characteristic differentiation of ortho- and ortho0-pro-
tons. There is only one exception for the case of octa-
4.2. UV–visible spectroscopy
The position (b-pyrrole or meso) of the substitu-
tion is the factor which affects more or less in each
case the spectrochemical properties of the macrocycle
(Table 5).
Table 2
1H NMR chemical shifts of complexes (Porph)InIIICl and (Porph)TlIIICl in CDCl3
Complex
para-H (p-H)
meta-H (m-H)
ortho-H (o-H)
ortho-H0 (o0-H)
pyr-H
(TpFPP)TlCl (1)
(TPyP)TlCl (2)
9.14 (J ¼ 61)a
9.13 (J ¼ 63:3)a
8.89
8.97 (J ¼ 75)a
9.11 (d)
7.75 (m)
7.73 (m)
7.79 (br)
8.37
8.10
(b-Cl4TPP)TlCl (3)
(b-Br4TPP)TlCl (4)
(b-Cl8TPP)TlCl (5)
7.84 (m)
7.84 (tr)
7.86 (tr)
8.14 (d)
8.14 (m)
8.16 (br)
8.03 (d)
8.04 (m)
8.16 (br)
(TpFPP)InCl (6)
(TPyP)InCl (7)
9.15
9.14
8.92
8.95
9.13 (d)
8.37
8.10
(b-Cl4TPP)InCl (8)
(b-Br4TPP)InCl (9)
(b-Cl8TPP)InCl (10)
7.83 (tr)
7.85 (tr)
7.86 (tr)
7.77 (m)
7.77 (m)
7.79 (s,br)
8.15 (m)
8.15 (m)
8.15 (s,br)
7.98 (m)
8.01 (m)
8.15 (s,br)
d in ppm.
a In parenthesis 205Tl–H coupling in Hz.

C. Raptopoulou et al. / Polyhedron 23 (2004) 1777–1784
1781
Table 3
19F NMR data for (TpFPP)MIIICl (M ¼ In, Tl) complexes in CDCl3
ortho-F (o-F)
ortho0-F (o0-F)
meta-F (m-F)
meta0-F (m0-F)
para-F (p-F)
a
(TpFPP)H2
(TpFPP)InIIICl
(TpFPP)TlIIICl
)136.92
)135.66
)135.84
)136.92
)137.34
)137.22
)161.81
)161.03
)161.09
)161.81
)161.6
)161.56
)151.70
)150.83
)150.84
d in ppm.
a Taken from [27].
Table 4
13C NMR data of (b-XnTPP)InIIICl and (b-XnTPP)TlIIICl(X ¼ Cl or Br n ¼ 4 or 8) in CDCl3
0
0
Co
Co
Cmeta
Cmeta
Cpara
Cph
Cmeso
Ca
Cb
(Cl4TPP)TlCl
134.57
135.02
127.67
127.48
129.96
140.18
122.65
151.98
151.97
150.03
150.65
133.79
129.65
133.86
137.86
133.72
135.34
134.22
137.8
(Br4TPP)TlCl
(Cl8TPP)TlCl
(Cl4TPP)InCl
134.48
135.80
134.56
135.17
135.44
134.73
127.48
128.64
127.56
127.79
128.41
127.37
129.24
130.15
129.04
141.20
144.20
140.60
123.12
122.8
121.55
(Br4TPP)InCl
(Cl8TPP)InCl
134.44
135.83
135.06
135.27
127.78
128.51
127.46
128.51
129.21
130.10
140.07
143.15
122.10
121.63
d in ppm.
Table 5
UV–visible data of (Porph)InIIICl and (Porph)TlIIICl complexes in toluene
B bands
Q(2,0)
Q(1,0) or b
Q(0,0) or a
b=a
(TpFPP)TlCl (1)
(TPyP)TlCl (2)
412 (4.63)
413 (4.53)
422 (4.57)
424 (4.63)
433 (5.70)
434 (5.66)
443 (5.47)
446 (5.58)
468 (5.35)
425 (5.63)
426 (5.79)
435 (5.61)
438 (5.64)
456 (5.51)
523 (3.48)
526 (3.41)
535 (3.46)
539 (3.59)
565
563 (4.38)
565 (4.29)
575 (4.14)
576 (4.26)
604 (3.98)
556 (4.38)
559 (4.35)
568 (4.27)
570 (4.32)
591 (4.10)
596 (3.25)
604 (3.77)
614 (3.79)
617 (3.920)
660 (4.04)
591 (3.34)
597 (3,72)
607 (3.81)
609 (3.90)
643 (4.02)
1.35
1.14
1.09
1.09
0.98
1.31
1.17
1.12
1.11
1.02
(b-Cl4TPP)TlCl (3)
(b-Br4TPP)TlCl (4)
(b-Cl8TPP)TlCl (5)
(TpFPP)InCl (6)
(TPyP)InCl (7)
359 (4.33)
363 (4.18)
393 (4.52)
403 (4.66)
405 (4.58)
412 (4.60)
416 (4.66)
516 (3.40)
520 (3.51)
529 (3.49)
532 (3.57)
552 (3.54)
330 (4.28)
352 (4.31)
358 (4.36)
387 (4.45)
(b-Cl4TPP)InCl (8)
(b-Br4TPP)InCl (9)
(b-Cl8TPP)InCl (10)
kmax (nm), log e (dmꢁ1 molꢁ1 cmꢁ1).
Theoretical as well as experimental work concerning
the tetraphenyl porphyrin has demonstrated that the
relative ordering of the a1u and a2u orbitals is particu-
larly sensitive to meso-substitution [28]. The a1u orbi-
tal localizes electron density predominantly on Ca
whereas a2u electron is concentrated on the meso posi-
tion. So, an electron-withdrawing group such as a per-
fluorophenyl group at the meso position is expected to
lower the energy of the a2u orbital with respect to a1u
[15].
In the case of halogenated complexes semi-empirical
AM1 and spectroscopic calculation revealed that both
the electronic properties of the halogen and the distor-
tion of the macrocycle results in a reduced HOMO–
LUMO energy gap [10,12,14,18,29]. On the other hand
theoretical calculations relative to the influence of me-
tal–porphyrin interactions on the energy of the frontier
orbital revealed that mainly the a2u orbital sensed the
metal perturbation which places considerable electron
density on the pyrrole nitrogen, while a1u has nodes
through the nitrogen and cannot interact directly with
the metal [28c,30].
The porphyrinic complexes 1, 2, 6 and 7 which are
meso substituted possess spectral features of ‘‘nor-
mal’’ type porphyrins [31] (Table 5) with no significant
shifts of kmax relative to the corresponding tetraphenyl
derivatives [2].
Metallation of tetrahalogenated porphyrin results in
bathochromically shifted bands. The intensity of the a
band increases relative to the tetraphenyl complexes of
In and Tl. This observation is more pronounced in the
case of octahalogenated complexes where the intensity
ratio of the molar absorptivities (b=a) is reduced. To a
first approximation the b=a value correlates with the
stabilization of the central metal [32]. The porphyrin
ring with a large b=a value stabilizes the central metal.
This is in good agreement with the reduced electron
density for the octahalogenated complexes.

1782
C. Raptopoulou et al. / Polyhedron 23 (2004) 1777–1784
The Soret band of the octa-halogenated complexes (5,
10) is red shifted relative to the free base, in contrast to
the four coordinated complexes which possess blue-
shifted Soret bands. [10,16]. The difference in kmax of the
Soret band between octahalogenated complexes 5, 10
and the meso substituted 1, 2, 6, 7 reflect the reduced
HOMO–LUMO energy gap expected in view of the ring
distortion as well as to the inductive effect of the halogen
atoms.
The differences observed concerning the kmax of the
Soret band for the two series of In and Tl complexes
with the same porphyrinic ligand can be attributed to
the different electronegativity values of the two metals.
More electronegative metals lower the a2u orbital
[28c,30b]. In addition, the ionic radii of the two metals
play an important role. The size of the ionic radius of Tl
ꢁ
(1.05 A) leads to an out of the D4N plane displacement
which is larger than that for the In complexes [33] and it
is also observed in the present X-ray structures.
4.3. Description of the structures
Fig. 2. ORTEP plot of (TpFPP)InCl (6).
The molecular structures of compounds 3, 6 and 8 are
shown as ORTEP plots in Figs. 1–3 respectively. Selected
bond distances and angles are listed in Table 6, structural
characteristics of the porphyrin core of all the three
structures are given in Table 7. Compounds 3 and 8 are
the corresponding thallium(III) and indium(III) com-
plexes of tetrachloro-tetraphenylporphyrin and are iso-
structural, so they will be discussed together. In both
compounds, the coordination geometry about the metal
is square pyramidal with the four nitrogen atoms of the
porphyrin defining the equatorial plane and the chloride
ion occupying the apical position. The M–N bond dis-
ꢁ
tances range from 2.199(6) to 2.220(6) A for 3 (average
ꢁ
value 2.210 A) and from 2.150(7) to 2.163(7) A for 8
ꢁ
Fig. 3. ORTEP plots of (b-Cl4TPP)InCl (8).
ꢁ
(average value 2.158 A). The M–Cl bond lengths are
ꢁ
2.442(2) and 2.367(3) A for 3 and 8 respectively. The
ꢁ
metal ion lies 0.70 and 0.58 A in 3 and 8 respectively, out
of the equatorial plane of the square pyramid toward the
axial chloride ligand. The presence of the metal ions along
with the substitution on the Cb and Cm atoms of the
porphyrin results in the distortion of the porphyrin core.
The presence of the chlorine atoms on Cb carbon atoms
of the porphyrin skeleton in both 3 and 8 results in the
saddling distortion of the ligand, expressed by the mean
absolute displacement of the Cb atoms from the C20N4
ꢁ
Fig. 1. ORTEP plot of (b-Cl4TPP)TlCl (3).
mean plane (0.39 A for C2, C7, C12, C13 in both 3 and 8).

C. Raptopoulou et al. / Polyhedron 23 (2004) 1777–1784
1783
Table 6
ꢁ
Selected bond distances (A), angles (°), and averages for (b-Cl4TPP)TlCl ꢂ C6H5CH3 (3), (b-Cl4TPP)TlCl ꢂ C6H5CH3 (8) and (TpFPP)InCl ꢂ 1.5(C6H6)
(6)
3 ꢂ C6H5CH3
8 ꢂ C6H5CH3
6 ꢂ 1.5(C6H6)
Bond distances
M–Cl
2.442(2)
2.212(6)
2.207(6)
2.199(6)
2.220(6)
1.376
2.367(3)
2.162(7)
2.150(7)
2.163(7)
2.156(7)
1.375
2.360(2)
2.154(5)
2.141(5)
2.161(5)
2.135(5)
1.367
M–N(1)
M–N(2)
M–N(3)
M–N(4)
N–Ca
Ca–Cb
X–Cb
1.453
1.446
1.442
1.691a
1.410
1.484
1.674b
1.403
1.494
–
1.398
1.505
Ca–Cm
Cm–Cphenyl
Bond lengths
(N–M–N)cis
(N–M–N)trans
(Cl–M–N)axial
Ca–N–Ca
84.2
142.9
108.6
109.2
107.6
107.8
126.3
85.9
149.0
105.5
108.7
107.7
107.9
125.8
86.2
149.9
105.0
108.1
108.3
107.6
125.7
N–Ca–Cb
Ca–Cb–Cb
N–Ca–Cm
a For Cl(1), Cl(3), Cl(5) and Cl(6) with occupancy 64%.
b For Cl(1), Cl(3), Cl(5) and Cl(6) with occupancy 60% (see text for details).
Table 7
down with respect to the porphyrin core mean plane by
9.21°–12.69° in 3 and 8.43°–12.33° in 8.
In compound 6, the nitrogen atoms of the tetra-
(pentafluorophenyl)porphyrin define the equatorial
plane of the square pyramidal geometry about the in-
dium(III) ion while the apical position is occupied by the
Structural characteristics of the compounds (b–Cl4TPP)Tl–
Cl ꢂ C6H5CH3 (3), (b–Cl4TPP)Tl–Cl ꢂ C6H5CH3 (8) and (TpFPP)In–
Cl ꢂ 1.5(C6H6) (6) indicating the distortion of the porphyrin core
Atom(s)
3 ꢂ C6H5CH3
8 ꢂ C6H5CH3
6 ꢂ 1.5(C6H6)
0.074
N
0.017
0.081
0.387a
0.689d
0.031
0.094
0.391a
0.689d
Cm
Cb
Cl1
0.061
0.097b, 0.101c
ꢁ
chloride ion. The metal ion lies 0.63 A out of the
equatorial plane towards the axial ligand. The In–N
–
ꢁ
bond distances range from 2.135(5) to 2.161(5) A (av-
ꢁ
erage value 2.148 A), and the In–Cl bond length is
Dihedral angles with the C20N4 mean plane
ꢁ
2.360(2) A. The lack of substitution on the Cb atoms of
the porphyrin skeleton is reflected in the small average
absolute displacement of these atoms from the C20N4
Group
3 ꢂ C6H5CH3
8 ꢂ C6H5CH3
6 ꢂ 1.5(C6H6)
4.16, 5.00
Pyrroles
12.69, 9.97
10.85, 9.21
76.71, 72.74
66.70, 65.10
12.33, 9.56
10.85, 8.43
76.66, 72.41
67.55, 64.12
3.33, 7.28
74.96, 89.58
87.23, 73.55
Phenyls
ꢁ
mean plane (0.097 and 0.101 A for C3, C8, C13, C18 and
C4, C9, C14, C19 respectively) and the small dihedral
angles formed between the pyrrole rings and the C20N4
mean plane (3.33°–7.28°). The average absolute dis-
Average absolute displacement of selected atoms of the porphyrin
from the C20N4 mean plane.
a Average absolute value of C(2), C(7), C(12) and C(13) displacements.
b Average absolutevalue of C(3), C(8), C(13) and C(18)displacements.
c Average absolute value of C(4), C(9), C(14) and C(19) displacements.
d AverageabsolutevalueofCl(1), Cl(3), Cl(5)andCl(6)displacements.
ꢁ
placement of the Cm atoms is also very small (0.061 A
for C1, C6, C11, C16) despite the pentafluoro-phenyl
substituents. The absence of Cb-substituents in the
porphyrin skeleton is also reflected in the large dihedral
angles formed between the pentafluoro-phenyl rings and
the C20N4 mean plane (73.55°–89.58°) due to the mini-
mization of the steric effects. These values are very close
to the ideal value of 90°, which is expected in the non-
substituted porphyrins.
The average absolute displacement of the corresponding
ꢁ
chlorine atoms bonded to Cb atoms is 0.69 A (for Cl1, Cl3,
Cl5, Cl6 in both 3 and 8). On the other hand, the average
absolute displacement of the Cm atoms from the por-
ꢁ
phyrin core (0.081 and 0.094 A in 3 and 8 respectively)
along with the rather large values of the dihedral angles
formed between the phenyl rings and the C20N4 mean
plane (65.10°–76.71° and 64.12°–76.66° in 3 and 8 re-
spectively) indicate that there is no twist distortion of the
porphyrin skeleton. The pyrrole rings are planar within
experimental error and they are tilted alternatively up and
5. Concluding remarks
All these complexes could be used as precursors for
the synthesis of new metal–metal bonded derivates with

1784
C. Raptopoulou et al. / Polyhedron 23 (2004) 1777–1784
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Crystallographic data for the structural analyses have
been deposited with the Cambridge Crystallographic
Data Center, CCDC 221431-221333. Copies of this in-
formation may be obtained free of charge from The
Director, CCDC, 12 Union Road, Cambridge, CB2
1EZ, UK (fax: +44-1223-336033); e-mail: deposit@
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