Crystal of meso-p-tolyl-porphyrinato copper(II) Cu(tptp) and di-cation ion-pair complex [H4tptp]2+ [CF3SO3]2- formation during the reaction of Cu(CF3SO3)2 with meso-p-tolyl-porphyrin in CDCl3

Article abstract of DOI:10.1016/S0277-5387(00)00294-1

In the NMR and ESR time-scale of this experiment, an attempt was made to prepare the copper sitting-atop (SAT) species [Cu(H₂tptp)]²⁺ by the reaction of Cu(CF₃SO₃)₂ with meso-p-tolyl-porphyrin (H₂tptp) in CDCl₃; however, this led to the formation of meso-p-tolylporphyrinatocopper(II) Cu(tptp) and the protonated porphyrin [H₄tptp]²⁺ [CF₃SO₃]₂^- (2a). Previous researchers might have misinterpreted the SAT [Cu(H₂tpp)]²⁺ complex as being a single component instead of a mixture of [H₄tpp]²⁺ [CF₃SO₃]₂^- (1) and Cu(tpp) for a similar reaction between 5,10,15,20-tetraphenylporphyrin H₂tpp and Cu(CF₃SO₃)₂ in CH₃CN. This work determines the crystal structure of Cu(tptp) and its hyperfine constants α(Cu) = 94.0 G and α(N) = 15.8 G using ESR. The crystal structure of [H₄tptp]²⁺ [CH₃SO₃]₂^- (3) is reported and employed to simulate the groupings of [H₄tptp]²⁺ and CF₃SO₃^- in the di-cation ion-pair complex 2a. (C) 2000 Elsevier Science Ltd.

Full text of DOI:10.1016/S0277-5387(00)00294-1

www.elsevier.nl/locate/poly
Polyhedron 19 (2000) 633–639
Crystal of meso-p-tolyl-porphyrinato copper(II) Cu(tptp) and di-cation
y
ion-pair complex [H4tptp]2q[CF3SO3]2 formation during the reaction
of Cu(CF3SO3)2 with meso-p-tolyl-porphyrin in CDCl3
b
b
Cheng-Hsi Tsai a, Jo-Yu Tung a, Jyh-Horung Chen a, , Feng-Ling Liao , Sue-Lein Wang ,
*
Shin-Shin Wang c, Lian-Pin Hwang d, Chie-Bein Chen e
a Department of Chemistry, National Chung-Hsing University, Taichung 40227, Taiwan
b Department of Chemistry, National Tsing-Hua University, Hsin-Chu 30043, Taiwan
c Union Chemical Laboratories, Hsin-Chu 30043, Taiwan
d Department of Chemistry, National Taiwan University and Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10764, Taiwan
e Department of Business Administration, Ming Chuan University, Taipei, Taiwan
Received 16 May 1999; accepted 4 January 2000
Abstract
In the NMR and ESR time-scale of this experiment, an attempt was made to prepare the copper sitting-atop (SAT) species[Cu(H2tptp)]2q
by the reaction of Cu(CF3SO3)2 with meso-p-tolyl-porphyrin (H2tptp) in CDCl3; however, this led to the formation of meso-p-tolyl-
porphyrinatocopper(II) Cu(tptp)and theprotonatedporphyrin [H4tptp]2q[CF3SO3]2y (2a). Previousresearchersmighthavemisinterpreted
the SAT [Cu(H2tpp)]2q complex as being a single component instead of a mixture of [H4tpp]2q[CF3SO3]2y (1) and Cu(tpp) for a similar
reaction between 5,10,15,20-tetraphenylporphyrin H2tpp and Cu(CF3SO3)2 in CH3CN. This work determines the crystal structure of Cu(tptp)
and its hyperfine constants aCus94.0 G and aNs15.8 G using ESR. The crystal structure of [H4tptp]2q[CH3SO3]2y (3) is reported and
employed to simulate the groupings of [H4tptp]2q and CF3SO3y in the di-cation ion-pair complex 2a.
q2000 Elsevier Science Ltd All
rights reserved.
Keywords: Crystal structures; Cu2q porphyrin complexes; Protonated porphyrins; SAT complexes; Electron spin resonance; Nuclear magnetic resonance
1. Introduction
Cu(CF3SO3)2 with H2tpp in CDCl3 under a dry N2 atmos-
phere; instead, a mixture (A) consisting of Cu(tpp) and
[H4tpp]2q[CF3SO3]2 (1) is observed. The proton NMR
y
Previously, Inada et al. [1,2] reported on the formation of
the ‘sitting-atop’ (SAT) complex [Cu(H2tpp)]2q via the
reaction of Cu(CF3SO3)2 with 5,10,15,20-tetraphenylpor-
phyrin (H2tpp) in acetonitrile under a dry nitrogen atmos-
phere. We have not been successful in synthesizing the
complex [Cu(H2tpp)]2q by repeatingthe previouswork[1]
using the same solvent acetonitrile. According to their sug-
gestion, the reaction of Cu(CF3SO3)2 with H2tpp in CHCl3
in the absence of a strong base should be easily arrested at
the formation of the SAT complex because of the low donor
number (DN) of CHCl3. It is known that the donor number
of chloroform (DNsy) is less than that of acetonitrile
(DNs14.1) [3]. Hence, we did not investigate the reaction
in the same solvent, i.e. chloroform. However, the SAT com-
plex [Cu(H2tpp)]2q is not detected in the reaction of
spectrum (1H NMR) for the Cu(tpp) in mixture A in CDCl3
shows a broad multiplet at 7.50 ppm for meta-hydrogens and
at 7.64 ppm for para-hydrogens (see Fig. 1 and Table 1).
1
The H NMR values are quite close to those of 7.48 ppm
(meta-H) and 7.62 ppm (para-H) for the compound
Cu(tpp) reported by Godziela and Goff [4]. The 1H NMR
data for 1 in mixture A in CDCl3 at 248C (see Fig. 1 and
Table 1) showed a singlet at 8.73 ppm (8H) for b-pyrrole
protons, a doublet at 8.61 ppm (8H) for ortho- protons and
a multiplet at 8.00 ppm (12H) for meta- and para- protons,
and a singlet at y1.84 ppm (with 4H) for the N-H protons.
Our interpretation of these data differs from that of Inada et
al. [1,2]. Inada et al. [1,2] might have misinterpreted the
1
mixture A as the SAT complex [Cu(H2tpp)]2q. The H
NMR data for their SAT complex in CD3CN at room tem-
perature (see Table 1) showed a singlet at 8.77 ppm (4H)
* Corresponding author. Fax: q886-4-2862574; e-mail: jhchen@
mail.nchu.edu.tw
0277-5387/00/$ - see front matter q2000 Elsevier Science Ltd All rights reserved.
PII S0277-5387(00)00294-1
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Fig. 1. 400.13 MHz 1H NMR spectrum for the mixture A consists of Cu(tpp) and [H4tpp]2q[CF3SO3]2y (1) in CDCl3 at 248C. Resonances due to Cu(tpp)
are labeled with an asterisk (*).
Table 1
Proton chemical shifts (d) for copper and protonated porphyrins in CDCl3 at 248C
Porphyrin
b-H
o-H
m-H
p-H
p-CH3
NH
CH3SO3
2.65
H2tptp
8.84
8.71
8.68
8.08
7.54
(7.7)
7.86
(7.2)
7.83
(8)
7.30
7.62
(6.0)
7.30
2.69
2.77
2.78
y2.79
y2.22
y1.74
(7.8) a
8.60
[H4tptp]2q[CH3SO3]2y (3) b
[H4tptp]2q[CF3SO3]2y (2b) c
(7.6)
8.50
(8)
7.48
8.48
Cu(tptp)4
2.52
2.77
2a in mixture B d
8.66
y1.76
(6.1)
Cu(tptp) in mixture B
Free ionic CH3SO3y [19]
H2tpp
2.53
2.80
8.89
8.74
8.25–8.27
8.60
(7.2)
7.74–7.81
8.00
y2.73
y1.84
[H4tpp]2q[CF3SO3]2y (1) c
(m) f
Cu(tpp)4
7.48
7.50
7.62
7.64
[Cu(H2tpp)]2q in CD3CN1
8.66(NH)
8.77(N)
8.73
8.10–8.12
7.31–7.50
y2.05
y1.84
1 in mixture A e
8.61
(6.9)
8.00
(m)
Cu(tpp) in mixture A
a 3J(H–H) coupling constant.
b Compound 3 was obtained by protonation of H2tptp with CH3SO3H.
c Compound 2b (or 1) was obtained by protonation of H2tptp (or H2tpp) with CF3SO3H.
d Mixture Bs2aqCu(tptp).
e Mixture As1qCu(tpp).
f msmultiplet.
for the coordinating b-pyrrole protons, a doublet at 8.66 ppm
(4H) for the uncoordinating b-pyrrole protons, one multiplet
at 8.10–8.12 ppm for ortho-phenyl protons and another mul-
tiplet at 7.31–7.50 ppm for the meta- and para-phenyl pro-
tons, and a singlet at y2.05 ppm (2H) for pyrrole N-H[1,2].
If the doublet centered at 8.61 ppm is due to the long-range
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C.-H. Tsai et al. / Polyhedron 19 (2000) 633–639
635
coupling of b-protons with a nitrogen-bonded proton of the
same pyrrole ring, the 4J(H–H) coupling constant should be
less than 4 Hz [5,6]. However, the coupling constant of 6.9
Hz is reasonably assigned to adjacent 1H–1H coupling, 3J(H–
H). Furthermore, the doublet at 8.61 ppm remainsunchanged
on irradiating the NH proton at d y1.84 ppm. In addition,
the doublet for the ortho- protons becomes a singlet on irra-
diating the meta- and para-phenyl protons at 8.00 ppm. Thus
the 1H NMR spectral data support the composition of mixture
A proposed by us and disagree with the SAT complex
reported previously [1,2].
When the porphyrin group (tpp) was substituted using
meso-p-tolyl-porphyrin (tptp), a mixture B consisting of
meso-p-tolyl-porphyrinatocopper(II) Cu(tptp) and the pro-
tonated porphyrin [H4tptp]2q[CF3SO3]2y (2a)wasformed
via the reaction of Cu(CF3SO3)2 with H2tptp in CDCl3.
Cu(tptp) was crystallized out in mixture B and its X-ray
structure is reported here. Both Cu(tptp) and 2a in mixture
l
B were characterized using ESR, H, 13C and 19F NMR
methods.
2. Experimental
2.1. Preparation of mixture B consisting of Cu(tptp) and
[H4tptp]2q[CF3SO3]2y (2a)
Fig. 2. The C-H COSY spectrum for the mixture B consists of Cu(tptp) and
complex 2a in CDCl3 at 248C. Resonances due to Cu(tptp) are labeled with
an asterisk (*).
H2tptp (0.5 mmol) and Cu(CF3SO3)2 (1 mmol, from
TCI) were dissolved inCDCl3 (15cm3, 99.8%fromAldrich)
under a nitrogen atmosphere and the mixture was stirred at
room temperature for 12 h. After the removal of unreacted
Cu(CF3SO3)2 through filtration, the filtrate consisting of
Cu(tptp) and 2a (i.e. the mixture B) was studied usingNMR
(Fig. 2) and ESR (Fig. 3) spectroscopy. Meanwhile, a blue–
purple crystal of Cu(tptp) was grown by slow evaporation
of CDCl3 from the solution of mixture B.
2.2. Preparation of [H4tptp]2q[CH3SO3]2y (3) and
[H4tptp]2q[CF3SO3]2y (2b)
Fig. 3. The first derivative ESR spectrum for Cu(tptp) of mixture B in
CDCl3 at 248C.
Compound 3 (or 2b) was obtained by protonation of
H2tptp (1 mmol) with 3 mmol of CH3SO3H (or CF3SO3H)
in CHCl3. Compound 3 was dissolved in CHCl3 and layered
with benzene. After 2 weeks, blue–green and equant shape
crystals of complex 3 were obtained for single-crystal X-ray
line of CDCl3 at 77.0ppm, respectively. l9Fdataareexternally
relative to CFCl3.
2.4. ESR spectra
1
analysis. H (or 13C, or 19F) NMR data for 2b and 3 are
ESR spectra were obtained with a Bruker EMX-10 X-band
spectrometer system operating at 9.726 GHz with 100 kHz
field modulation.
shown in Table 1 (or Table 2), respectively.
2.3. NMR spectra
1H and 13C NMR spectra in CDCl3 were recordedat400.13
and 100.61 MHz, respectively, on a Bruker AM-400 spec-
trometer. The 19F NMR spectra were measured in CDCl3 at
376.76 or 282.40 MHz, on a Varian Mercury-400 or Bruker
MSL-300 spectrometer. The reference peaks in 1H NMR and
13C NMR are relative to CHCl3 at 7.24 ppm and the center
2.5. Crystallography
Table 3 presents crystal data and other information for
Cu(tptp) and [H4tptp]2q[CH3SO3]2yP2CHCl3 (3P2CHCl3).
Measurements were taken on a Siemens SMART CCD
diffractometer using monochromatic Mo Ka radiation
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C.-H. Tsai et al. / Polyhedron 19 (2000) 633–639
Table 2
13C and 19F NMR chemical shifts (d) for [H4tptp]2q[CF3SO3]2y (2a) and Cu(tptp) in mixture B in CDCl3 at 248C
Porphyrin
Ca
C1
C4
C2,6
Cb
C3,5
Cm
p-CH3
CF3SO3
CH3SO3
38.0
CF3SO3 (19F)
H2tptp
139.4
141.0
140.9
137.4
136.9
137.0
134.6
139.0
138.6
131.1
128.5
128.7
127.4
129.4
129.3
120.1
123.1
122.9
21.5
21.6
21.6
[H4tptp]2q[CH3SO3]2y (3) a
[H4tptp]2q[CF3SO3]2y (2b) a
145.8
145.8
116.9
y81.1
y81.2
(320)
116.2 c
(318) d
2a in mixture B b
145.9
140.9
137.1
138.7
128.8
129.3
127.1
123.0
21.6
21.4
Cu(tptp) in mixture B
Free ionic CF3SO3y [19]
121.0
(321)
y78.7
Free ionic CH3SO3y [19]
41.3
a The preparation of compounds 3 and 2b is shown in Table 1.
b Mixture Bs2aqCu(tptp).
c Measured at y508C.
d 1J(C–F) coupling constant.
Table 3
Table 4
˚
Crystal data for Cu(tptp) and 3P2CHCl3
Selected bond distances (A) and angles (8) for Cu(tptp) and 3P2CHCl3
Empirical formula
FW
Space group
C48H36CuN4
732.3
P21/n
C52H48Cl6N4O6S2
1101.8
P43212
Cu(tptp)
Cu(1)–N(1)
Cu(1)–N(2)
2.000(4)
1.994(4)
Crystal system
monoclinic
black lamellar
9.9271(4)
9.2107(4)
20.9383(5)
98.533(2)
1893.3(6)
2
1.285
6.16
1.03
0.07=0.08=0.31
56.0
296
5636
1544
tetragonal
blue equant
17.6633(3)
Cu(1)–N(1)–C(2)
Cu(1)–N(1)–C(5)
Cu(1)–N(2)–C(7)
Cu(1)–N(2)–C(10)
N(1)–Cu(1)–N(1a)
N(1)–Cu(1)–N(2)
127.2(3)
127.4(4)
127.4(4)
126.9(3)
180.0(1)
90.0(2)
Crystal color, habit
˚
a (A)
˚
b (A)
˚
c (A)
16.8444(4)
b (8)
3
˚
V (A )
5255(1)
4
1.392
4.59
3P2CHCl3
Z
Dcalc (g cmy3
)
S(1)–C(30)
S(1)–O(1)
S(1)–O(2)
S(1)–O(3)
N(2)–C(7)
N(2)–C(10)
N(1)–C(2)
N(1)–C(5)
1.748(8)
1.442(5)
1.433(5)
1.463(4)
1.390(7)
1.367(6)
1.390(7)
1.370(6)
m(Mo Ka) (cmy1
S
)
1.08
Crystal size (mm)
2umax (8)
T (K)
0.19=0.25=0.30
55.8
296
19092
2916
No. reflections measured
No. reflections observed
(IG3.0s(I))
C(30)–S(1)–O(1)
C(30)–S(1)–O(2)
C(30)–S(1)–O(3)
O(1)–S(1)–O(2)
O(1)–S(1)–O(3)
O(2)–S(1)–O(3)
C(7)–N(2)–C(10)
N(2)–C(10)–C(11)
N(2)–C(10)–C(9)
N(2)–C(7)–C(6)
N(2)–C(7)–C(8)
C(7)–C(6)–C(5)
C(7)–C(6)–C(16)
106.3(3)
106.1(3)
106.4(3)
114.5(3)
111.8(3)
111.2(3)
110.6(4)
127.2(5)
106.5(4)
126.6(4)
105.4(4)
123.3(5)
120.4(4)
R (%) a
4.57
4.95
5.27
5.55
Rw (%) b
a Rs[8NNFoNyNFcNN/8NFoN].
b Rws[8w(NNFoNyNFcNN)2/8w(NFoN)2]1/2; wsA/(s2FoqBFo2).
˚
(ls0.71073 A). Next, absorption corrections were based
on 3191 (or 13717) symmetry-equivalent reflections using
the SHELXTL-PC program package with Tmins0.481,
Tmaxs0.962 or Tmins0.786, Tmaxs0.942 for Cu(tptp) and
3P2CHCl3, respectively. The structures were solved by direct
methods (SHELXTL PLUS) and refined using full-matrix
least-squares. All non-hydrogen atoms were refined with ani-
sotropic thermal parameters, whereas all hydrogen-atom
positions were located on a difference map (or were calcu-
lated using a riding model) and included in the structure
factor calculation for Cu(tptp) and 3P2CHCl3. Table 4 out-
lines selected bond distances and angles for both com-
plexes.
3. Results and discussion
3.1. Molecular structure of Cu(tptp)
Crystals of Cu(tptp) were obtained by slow evaporation
of CDCl3 from the mixture B. Fig. 4(a) illustratestheskeletal
framework of complex Cu(tptp), with P21/n symmetry.This
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C.-H. Tsai et al. / Polyhedron 19 (2000) 633–639
637
CutTEtpp (H2tTEtpps2,3,12,13-tetraethyl-5,10,15,20-tetra-
˚
phenylporphyrin), 1.975 A in CucTEtpp (H2cTEtpps
2,3,7,8-tetraethyl-5,10,15,20-tetraphenylporphyrin)
and
˚
1.980 A in CuHEtpp (H2HEtpps2,3,7,8,12,13-hexaethyl-
5,10,15,20-tetraphenylporphyrin) [11]. Interestingly, the
structure of Cu(tptp) is also isomorphic to that of meso-p-
tolyl-porphyrinatozinc(II) Zn(tptp) [12].
3.2. The crystal structure of [H4tptp]2q[CH3SO3]2yP
2CHCl3 (3P2CHCl3)
Each porphyrin nucleus is associated with two complex
y
anions CH3SO3 (Fig. 4(b)). First, the contacts between
the porphyrin nitrogen atoms N(2) (or N(1a)) and O(3) of
˚
the anion are 2.866 (or 2.927 A), and these are short enough
to permit hydrogen bonding of the type N–H∆O. The mean
N∆O distance in these types of hydrogen bonds is calculated
˚
as 2.90 A. Second, the H∆O distances (based on the refined
˚
hydrogen atom positions) are 1.94 A for O(3)∆H(2) and
˚
1.98 A for O(3)∆H(la). The mean H∆O distance in hydro-
˚
gen bonds is calculated as 2.60 A. Third, the values of N–
H∆O angles are close to linear values with 171.58 for N(2)–
H(2)∆O(3) and 163.28 for N(la)–H(1a)∆O(3). Allthese
results indicate that two triflate anions are hydrogen bonded
to the pyrrole hydrogens in a monodentate bridging fashion,
with one O(3) (or O(3a)) bonded to two opposite N-H
protons, i.e. H(2) and H(la) (or H(1) and H(2a)), on the
same face of the porphyrin [13]. The four phenyl group–
porphyrin dihedral angles in 3P2CHCl3 are 35.48 (C(15)),
and 31.48 (C(19a)), 40.08 (C(25)) and 31.48 (C(l9)).
These dihedral angles are quite acute, averaging only 34.68.
They are slightly larger than the average 278 in [H2tpp]-
[ClO4]2 but smaller than 638 (or 758) in [H4tmp][ClO4]2
[14]. The distortion (C20N4) of 3P2CHCl3 is saddle shaped.
Fig. 4. Molecular configuration and atom-labeling scheme for (a) Cu(tptp)
and (b) 3P2CHCl3, with ellipsoids drawn at 20% probability. The refined
positions of the hydrogen atoms bonded to the pyrrole nitrogens are shown
for 3P2CHCl3; all other hydrogen atoms for both compounds and solvents
C(29)H(29a)Cl(l)Cl(2)Cl(3) for 3P2CHCl3 are omitted for clarity.
˚
Fig. 5 depicts the displacement (in A) of each atom of the
structure has a four-coordinate copper with four nitrogen
atoms of the porphyrinato group. Bond distances are Cu(1)–
˚
N(1)s2.000(4) and Cu(1)–N(2)s1.994(4) A. The
C20N4 core is essentially planar. The Cu(1) sits at the inver-
sion center, so the angles N(1)–Cu(1)–N(1a) and N(2)–
Cu(1)–N(2a) are 180.0(1)8. The dihedral angles between
the mean plane of the skeleton (C20N4) and the planes of the
phenyl groups are 68.48 (C(14)) and 87.58 (C(20)).
The radius of the central hole (Ct9∆N, the distance from
the geometrical center Ct9 of the mean plane of the 24-atom
˚
core to the porphyrinato-core N atoms) is 1.997 A (or ;2.00
˚
˚
A) which is similar to the value of ;2.01 A suggested by
Collins and Hoard [7]. Hence, the copper(II)atomisbonded
and centered in a porphyrinato core (C20N4) with ‘radial
˚
strain’ being minimized. The average distance of 1.997 A in
Cu(tptp) is comparable with the observed Cu–N distances
Fig. 5. Schematic diagram of the porphyrin core (C20N4) and four inner
hydrogen atoms of 3P2CHCl3 in which each atom symbol is replaced by a
˚
˚
of 1.981 A in Cu(tpp) [8], 1.998 A in Cu(oep) (H2oeps
˚
octaethylporphyrin) [9], 1.997 A in Cu(oetpp) (H2oe-
˚
number showing the displacement (in A) of that atom from the mean plane
˚
˚
tppsoctaethyltetraphenylporphyrin) [10], 1.984 A in
of the porphyrin (C20N4) with a typical esd of 0.003 A.
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C.-H. Tsai et al. / Polyhedron 19 (2000) 633–639
porphyrin from the porphyrin mean plane (C20N4) as well as
displacements of the four central hydrogen atoms. The pyr-
role NH protons are alternately displaced above and below
respectively. Owing to the paramagnetic copper(II) ion in
Cu(tptp), the l3C NMR spectrum of Cu(tptp) (see Fig. 2 and
Table 2) shows only two peaks at 127.1 (C3,5) and 21.4 ppm
(p-CH3). The 13C, l9F and lH NMR data for 2a in mixture B
shown in Tables 1 and 2 are consistent with those of
˚
˚
the 24-atom mean plane by y0.69 A for H(1), 0.71 A for
˚
˚
H(2), y0.71 A for H(2a), and 0.69 A for H(1a). The out-
of-plane displacements of the inner hydrogen atoms help to
relieve steric strain [15]. The groupings of [H4tptp]2q and
CH3SO3y of 3 in CDC13 retain their basic properties when
bonded together by hydrogen bonds called an ion-pair.
Although the structures of Cu(tpp) [8], Cu(oep) [9],
Cu(oetpp) [10], CutTEtpp [11], CucTEtpp [11], CuHEtpp
[11] and the di-cation of tetraarylporphyrin species
[H4por](ClO4)2 [14], [H4por](TFA)2 (TFAstrifluoro-
acetate) [15], and [H4por](OAc)3/2(TFA)1/2 [15]
(porstpp, oep, oetpp) have already been published,
Cu(tptp) and 3 are two new crystal structures with different
porphyrin (tptp) and counter ion (CH3SO3y).
y
[H4tptp]2q[CF3SO3]2 (2b) obtained by protonation of
H2tptp using CF3SO3H. Notably, these consistencies suggest
that complex 2a is 2b. Furthermore, thel3C (orl9F)resonance
of CF3SO3y for compound 2a at ds116.2 ppm with lJ(C–
F) coupling constant 318 Hz (or y81.2 ppm) is different
from that of free ionic CF3SO3y, i.e. Bu4NqCF3SO3y, with
l
ds121.0 and J(C–F)s321 Hz (or y78.7 ppm) at room
temperature [18,19]. Hence, the mutual geometric arrange-
ment of the [H4tptp]2q, CF3SO3y and the solvent CDCl3 in
complex 2a is explained as ion pairs. The intramolecular
electric fields in the ion-pair complex 2a cause considerable
upfield shifts of y4.8 ppm (from 121.0 to 116.2 ppm) for
the triflate carbon and about y2.5 ppm (from y78.7 to
y81.2 ppm) for the 19F resonance in the samecomplex[20].
3.3. NMR spectra of Cu(tptp) and [H4tptp]2q[CF3SO3]2
y
y
y
(2a) in mixture B
When the CF3 of 2a was replaced by a CH3 group, the
y
complex 2a became [H4tptp]2q[CH3SO3]2 (3). In the
The net reaction of Cu(CF3SO3)2 with H2tptp in CDCl3 is
known by Eqs. (1) and (2), where 2a is a di-cation ion-pair
complex [16].
absence of the crystal structure of 2a, the close resemblance
of l3C and lH data (shown in Tables 1 and 2) for the di-cation
[H4tptp]2q of 2b and 3 indicates a similar structure for these
two complexes. Two CH3SO3y anions axial and hydrogen-
bonded to the pyrrole hydrogen in 3 (shown in Fig. 4(b))
y
suggest that two CF3SO3 might be located on the axial
position of the porphyrin ring (C20N4) of 2a. The upfield
shift of about y3.3 ppm (from 41.3 (obtained from free
CH3SO3y, i.e. CsqCH3SO3y) [19] to 38.0 ppm) for carbon
of CH3SO3 in 3 is due to the same electric field as in complex
2a. Nevertheless, the 1H chemical shift of CH3SO3 in 3 expe-
rienced an upfield shift of y0.15 ppm from 2.8 (obtained
from free CH3SO3y) [19] to 2.65 ppm, being controlled by
the ring current effect.
(1)
H2 tptpq2CF3 SO3 H™[H4 tptp]2q[CF3 SO3]2y
(2a)
(2)
The SAT complex [Cu(H2tptp)]2q has been proposed as an
intermediate. Loss of the N-H protons and CF3SO3y ligand
produces Cu(tptp) and CF3SO3H. Finally, protonation of the
remaining H2tptp produces the ion-pair complex 2a between
the meso-p-tolyl-porphyrin di-cation [H4tptp]2q and triflate
(CF3SO3y). Only Cu(tptp) and complex 2a are observed
by H NMR in our system. The H NMR spectrum for
Cu(tptp) in mixture B in CDCl3 (see Table 1 and Fig. 2)
shows m-phenyl signals at 7.30 ppm and methyl protons at
2.53 ppm. These values are quite close to the corresponding
signals at 7.30 ppm for the m-phenyl protons and 2.52 ppm
for the methyl protons in complex Cu(tptp) reported by God-
ziela and Goff [4]. The N-H signals are downfield shifted by
;1.03 ppm from y2.79 (for H2tptp) to y1.76 ppm for
complex 2a by protonation. The similar downfield shift due
to protonation is also reflected by observing a 4.2–4.7 ppm
downfield shift of N-H at y2.588 and y2.672 ppm for
H2Cttp (4) (2-aza-21-carba-5,10,15,20-tetra-p-tolylpor-
phyrin), compared to 2.034, 1.877 and 1.612 ppm for [4-
H2]2q [17]. In complex 2a, the integrated peak areas are
8:8:8:4 for the b-pyrrole:o-phenyl:m-phenyl:N-H protons,
3.4. ESR spectra for Cu(tptp) in mixture B
Cu(tptp) are paramagnetic because of the d9 configuration
2
2
of Cu(II). The unpaired electron resides in the dx yy orbital,
which leads to characteristic EPR spectra for Cu(tptp): four
peaks due to the nuclear spin (Is3/2) of the Cu and super-
hyperfine interaction with the four nitrogens (Is1) of the
porphyrin. Cu(tptp) in CDCl3 exhibits a typical Cu(II) por-
phyrin EPR spectrum as shown in Fig. 3. The experimental
spectrum yields aCus94.0 G and four nitrogens with
aNs15.8 G. These data are similar to those reported,
aCus90.5 G and aNs15.8 G for Cu(tpp) [21], aCus90 G
and aNs15 G for Cu(oep) [9], or aCus86.5 G and aNs
14.4 G for Cu(oetpp) [10].
1
1
4. Conclusions
Inada postulated that in the reaction of Cu(II) with H2tpp
in CH3CN, an intermediate complex species forms,
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C.-H. Tsai et al. / Polyhedron 19 (2000) 633–639
639
[Cu(H2tpp)]2q, in which the metal stays above the tetra-aza
plane. We have repeated the reaction using a slightlydifferent
porphyrin (H2tptp) in less basic solvent CDCl3, and have
crystallized from the solution the Cu(tptp) and the doubly
protonated ligand [H4tptp]2q[CF3SO3]y (2a), which dem-
onstrates that the H2tptp acts simultaneously as Cu2q com-
plexation and as a proton receptor.
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The authors would like to thank the National Science
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this work under Contract No. NSC 88-2113-M-005-017.
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