Metal complexes of N-o-chlorobenzamido-meso-tetraphenylporphyrin: cis-Tl(N-NCO(o-Cl)C6H4-tpp)(OAc) and trans-Cd(N-NHCO(o-Cl)C6H4-tpp)(OAc) (tpp = 5, 10, 15, 20-tetraphenylporphyrinate)

Article abstract of DOI:10.1016/j.inoche.2010.01.022

The crystal structures of diamagnetic (cis-acetato) (N-o-chlorobenzamido-meso-tetraphenylporphyrinato)thallium(III)·0.5 water solvate [cis-Tl(N-NCO(o-Cl)C₆H₄-tpp)(OAc)·0.5 H₂O; 3·0.5 H₂O] and diamagnetic (trans-acetato) (N-o-chlorobenzamido-meso-tetraphenylporphyrinato)cadmium(II) methylene chloride solvate [trans-Cd(N-NHCO(o-Cl)C₆H₄-tpp)(OAc)·CH₂Cl₂; 4·CH₂Cl₂] were determined. The coordination sphere around the Tl³⁺ (or Cd²⁺) in 3 (or 4) is a distorted square-based pyramid in which the apical site is occupied by a chelating bidentate OAc^- group. In 3, Tl³⁺ and N(5) are located on the same side at 1.18 and 1.26 A? from it 3N plane, but in 4, Cd²⁺ and N(5) are located on different sides at 1.06 and -1.55 A? from it 3N plane. The free energy of activation at the coalescence temperature T_c for the intermolecular acetate exchange process in 3 in CD₂Cl₂ solvent is found to be Δ G₁₉₈^≠ = 42.1 kJ/mol through ¹H NMR temperature-dependent measurements. Likewise, the free energy of activation Δ G₂₉₃^≠ = 55.94 kJ/mol is determined for the intramolecular exchange of the ortho protons between o′-H (34, 40) and o′-H (38, 44) in 3 in CD₂Cl₂. VT NMR (¹H and ¹³C) studies of 4 show that the acetate acts as a bidentate ligand and the OAc^- exchange does not occur in CD₂Cl₂. Moreover, the NH proton [i.e., H(5)] of 4 in CD₂Cl₂ is observed as a singlet at δ -0.09 ppm with Δν_1/2 = 13 Hz at 20 °C indicating that the NH protons undergo intermediate intermolecular proton exchange with water at this temperature.

Full text of DOI:10.1016/j.inoche.2010.01.022

Inorganic Chemistry Communications 13 (2010) 506–510
Contents lists available at ScienceDirect
Inorganic Chemistry Communications
journal homepage: www.elsevier.com/locate/inoche
Metal complexes of N-o-chlorobenzamido-meso-tetraphenylporphyrin:
cis-Tl(N-NCO(o-Cl)C6H4-tpp)(OAc) and trans-Cd(N-NHCO(o-Cl)C6H4-tpp)(OAc)
(tpp = 5, 10, 15, 20-tetraphenylporphyrinate)
b
c,*
Kwan-Tin Chen a, Ming Yang Tsai a, Jyh-Horung Chen a, , Shin-Shin Wang , Jo-Yu Tung
*
a Department of Chemistry, National Chung-Hsing University, Taichung 40227, Taiwan
b Material Chemical Laboratories, Hsin-Chu 300, Taiwan
c Department of Occupational Safety and Health, Chung Hwai University of Medical Technology, Tainan 717, Taiwan
a r t i c l e i n f o
a b s t r a c t
Article history:
The crystal structures of diamagnetic (cis-acetato) (N-o-chlorobenzamido-meso-tetraphenylporphyrin-
ato)thallium(III)ꢀ0.5 water solvate [cis-Tl(N-NCO(o-Cl)C6H4-tpp)(OAc)ꢀ0.5 H2O; 3ꢀ0.5 H2O] and
diamagnetic (trans-acetato) (N-o-chlorobenzamido-meso-tetraphenylporphyrinato)cadmium(II) methy-
lene chloride solvate [trans-Cd(N-NHCO(o-Cl)C6H4-tpp)(OAc)ꢀCH2Cl2; 4ꢀCH2Cl2] were determined. The
coordination sphere around the Tl3+ (or Cd2+) in 3 (or 4) is a distorted square-based pyramid in which
the apical site is occupied by a chelating bidentate OAcꢁ group. In 3, Tl3+ and N(5) are located on the
same side at 1.18 and 1.26 Å from it 3N plane, but in 4, Cd2+ and N(5) are located on different sides at
1.06 and ꢁ1.55 Å from it 3N plane. The free energy of activation at the coalescence temperature Tc for
Received 14 December 2009
Accepted 28 January 2010
Available online 4 February 2010
Keywords:
Thallium
Cadmium
X-ray diffraction
N-Substituted-N-aminoporphyrin
Dynamic NMR
the intermolecular acetate exchange process in 3 in CD2Cl2 solvent is found to be
D
G–198 ¼ 42:1 kJ/mol
through 1H NMR temperature-dependent measurements. Likewise, the free energy of activation
D
G–293 ¼ 55:94 kJ/mol is determined for the intramolecular exchange of the ortho protons between o0-
H (34, 40) and o0-H (38, 44) in 3 in CD2Cl2. VT NMR (1H and 13C) studies of 4 show that the acetate
acts as a bidentate ligand and the OAcꢁ exchange does not occur in CD2Cl2. Moreover, the NH proton
[i.e., H(5)] of 4 in CD2Cl2 is observed as a singlet at d ꢁ0.09 ppm with
Dm1/2 = 13 Hz at 20 °C indicating
that the NH protons undergo intermediate intermolecular proton exchange with water at this
temperature.
Ó 2010 Elsevier B.V. All rights reserved.
Previously, we reported two-stage formation of (N-o-chlo-
robenzamido-meso-tetraphenylporphyrinato)(methanol)zinc(II)
methanol solvate [Zn(N-NCO(o-Cl)C6H4-tpp)(MeOH)ꢀMeOH; 1ꢀ
MeOH] [1]. Compound 1 is a zinc complex of N-NHCO(o-Cl)
distorted trigonal prismatic Tl (III) derivative, that is, (cis-aceta-
to)(N-o-chlorobenzimido-meso-tetraphenylporphyrinato)thallium
(III)ꢀ0.5 water solvate [Tl(N-NCO(o-Cl)C6H4-tpp)(OAc)ꢀ0.5 H2O;
3ꢀ0.5 H2O] possessing a nitrene moiety inserted between the thal-
lium atom and one nitrogen atom, N(4) (Scheme 1). During the
metallation of free base 2 with Cd(OAc)2, the soft acid Cd2+ with
a lower polarizing power (2.041) prefers to retain one OAcꢁ ligand
and coordinate to the N–H proton [i.e. H(2A)] of 2 also to form a
six-coordinate distorted trigonal prismatic complex, that is,
(trans-acetato)(N-o-chlorobenzimido-meso-tetraphenylporphyrin-
ato)cadmium(II) methylene chloride solvate [trans-Cd(N-NHCO(o-
Cl)C6H4-tpp)(OAc)ꢀCH2Cl2; 4ꢀCH2Cl2] (Scheme 1). In this paper,
we describe the X-ray structural investigation on the complexation
of Tl3+ and Cd2+ classified as C acids (covalent acids) but with dif-
ferent polarizing power into 2 leading to mononuclear complexes
of cis-3 and trans-4 [4,5]. In addition, the 1H and 13C NMR spectra
of cis-3 in CD2Cl2 at various temperatures are used to investigate
the intermolecular apical ligand (OAcꢁ) exchange process and in
turn to determine the free energy of activation at the coalescence
C6H4-Htpp) (2) (Chart 1). The absolute values of hardness
g for
Zn2+, Tl3+ and Cd2+ are 10.88, 10.4, and 10.29 eV, respectively [2].
It is observed that the effective ionic radius (r) for the metal ion in-
creases from 0.82 Å for Zn2+ (S = 0) with coordination number
(CN) = 5 [or 1.025 Å for Tl3+ (S = 0) with CN = 6] to 1.09 Å for Cd2+
(S = 0) with CN = 6 [3]. In these three metal ions the polarizing
power z/r2 (z = charge on the cation, r = ionic radius) decreases
from 3.652 (Zn2+) [or (Tl3+)] to 2.041 (Cd2+) [4,5]. The metal cations
of different polarizing power selected were Tl3+ and Cd2+. The soft
acid Tl3+ with a larger polarizing power (2.855) similar to that of
Zn2+ attacks the two N–H protons of 2 and lead to a six-coordinate
* Corresponding authors. Tel.: +886 4 228 40411x612; fax: +886 4 228 62547
(J.H. Chen), tel.: +886 6 267 4567x815; fax: +886 6 289 4028 (J.Y. Tung).
E-mail addresses: JyhHChen@dragon.nchu.edu.tw (J.-H. Chen), joyuting@mail.
hwai.edu.tw (J.-Y. Tung).
temperature,
D
G–Tc, for the exchange process.
1387-7003/$ - see front matter Ó 2010 Elsevier B.V. All rights reserved.
doi:10.1016/j.inoche.2010.01.022

K.-T. Chen et al. / Inorganic Chemistry Communications 13 (2010) 506–510
507
3N. The geometry around Tl (III) (or Cd (II)) is a distorted square-
based pyramid in which the apical site is occupied by a chelating
bidentate OAcꢁ group in 3 (or 4). In complex 3, Tl (III) and N(5)
are located on the same side at 1.18 and 1.26 Å from its 3N plane,
but for complex 4, Cd (II) and N(5) are located on different sides at
1.06 and ꢁ1.55 Å from its 3N plane. Apparently, chelating biden-
tate OAcꢁ in 3 is cis to the (o-Cl)BA group with O(2) and O(3) being
located separately at 2.95 and 3.13 Å out of the 3N plane, and
bidentate OAcꢁ in 4 is trans to the (o-Cl)BA group with O(2) and
O(3) located at 3.21 and 2.85 Å out of the 3N plane.
Cl
Cl
O
O
C
C
N
N
N
NH(5A)
N
N
N
Zn
N
N
H(2A)
N
MeOH
The N(4) pyrrole rings bearing the (o-Cl)BA group in 3 and 4
deviate mostly from the 3N plane, thus orienting separately with
a dihedral angle of 47.6° and 30.8°, whereas small angle of 7.5°,
13.5° and 9.8° occur with N(1), N(2) and N(3) pyrrole for 3 and
the corresponding angles are 21.8°, 1.4 ° and 17.0° with N(1),
N(2) and N(3) pyrrole for 4. In 3, such a large deviation from pla-
narity for the N(4) pyrrole is also reflected by observing a 16.2–
20.3 ppm upfield shift of the Cb (C17, C18) at 115.4 ppm compared
to 134.1 ppm for Cb (C2, C13), 134.1 ppm for Cb (C3, C12) and
131.6 ppm for Cb (C7, C8). In 4, a similar deviation is also found
for N(4) pyrrole by observing a 7.4–10.1 ppm upfield shift of Cb
(C17, C18) at 124.0 ppm compared to 134.1 ppm for Cb (C3, C12),
134.0 ppm for Cb (C7, C8) and 131.4 ppm for Cb (C2, C13). The dihe-
dral angles between the mean plane of the skeleton (3N) and the
planes of the phenyl groups are 88.1° [C(24)], 54.1° [C(30)], 42.7°
[C(36)] and 36.2° [C(42)] for 3 and the corresponding angles are
61.1°, 51.7°, 39.9° and 36.4° for 4.
In solution, the molecule has effective Cs symmetry with a mir-
ror plane running through the N(4)–N(5)–Tl(1)–N(2) unit for 3 and
the N(2)–Cd–N(4)–N(5) unit for 4. As a result, the 1H NMR spec-
trum will exhibit four pyrrole resonances [Hb (2, 13), Hb (3, 12),
Hb (7, 8), Hb (17, 18)] for these two complexes (Figs. 2 and 3).
Fig. 2 depicts the representative 1H spectra for 3 in CD2Cl2 at 20
and ꢁ90 °C. The NMR study of 3 showed three different types of
Tl–H coupling constants for Hb. In 3 at 20 °C, the doublet at
9.30 ppm is assigned as Hb (2, 13) with 4J(Tl–H) = 10.8 Hz and the
other doublet at 8.59 ppm is due to Hb (7, 8) with 4J(Tl–
(1)
(2)
Chart 1.
Using a d10 metal, namely, thallium(III) and cadmium(II), the
new complexes 3 and 4 were synthesized. The synthetic strategy
is outlined in Scheme 1. The complex cis-Tl(N-NCO(o-Cl)C6H4-
tpp)(OAc) (3) was produced in 63% yield by heating a N-NHCO(o-
Cl) C6H4-Htpp) (2) solution in CH2Cl2/MeOH under aerobic condi-
tions with an excess of Tl(OAc)3 (Scheme 1). The complex trans-
Cd(N-NHCO(o-Cl)C6H4-tpp)(OAc) (4) was synthesized in 53% yield
by reacting 2 with excess Cd(OAc)2 in CH3CN under aerobic condi-
tions (Scheme 1). The molecular frameworks are depicted in Fig. 1a
for 3ꢀ0.5H2O and in Fig. 1b for 4ꢀCH2Cl2. The cadmium–nitrogen
bond distances are comparable to those of Cd(1)–N(p) =
2.301(5) Å in Cd(N-NHCOC6H5-tpp)(OAc) [6]. The Cdꢀ ꢀ ꢀN(4) dis-
tance of 2.600(4) Å for 4 is longer than 2.301(5) Å but is signifi-
cantly shorter than the sum of the van der Waals radii of Cd and
N (3.15 Å) [3]. This longer Cdꢀ ꢀ ꢀN(4) contact in 4 may be viewed
as a secondary intramolecular interaction. Most chemists seems
to consider this secondary interaction between the metal ion and
the fourth N as a weak bond in N-substituted porphyrin metal
complexes [7,8] .
We adopt the plane of three strongly bound pyrrole nitrogen
atoms [i.e., N(1), N(2) and N(3)] for 3 and 4 as a reference plane,
Cl
O
C
O
O
N
N
N
N
Tl
Tl(OAc)3
N
Cl
CH2Cl2 / MeOH
60° 3h
O
C
63 %
cis-3
N
Cl
NH
HN
N
O
C
N
N
NH
Cd(OAc)2
N
N
Cd
N
(2)
CH3CN
50° 3h
O
O
59 %
trans-4
Scheme 1.

508
K.-T. Chen et al. / Inorganic Chemistry Communications 13 (2010) 506–510
Fig. 1. (a) Molecular structure of cis-Tl(N-NCO(o-Cl)C6H4-tpp)(OAc)ꢀ0.5H2O (3ꢀ0.5H2O) and (b) trans-Cd(N-NHCO(o-Cl)C6H4-tpp)(OAc)ꢀCH2Cl2 (4ꢀCH2Cl2), with 30% thermal
ellipsoids. Hydrogen atoms, solvent H2O for 3ꢀ0.5H2O and solvent CH2Cl2 for 4ꢀCH2Cl2 are omitted for clarity. Selected bond distances (Å): Tl(1)–N(1), 2.382(3); Tl(1)–N(2),
2.148 (3); Tl(1)–N(3), 2.350(3); Tl(1)–N(5), 2.131(3); Tl(1)–O(2), 2.299(3); Tl(1)–O(3), 2.432(3) for 3ꢀ0.5H2O; Cd–N(1), 2.294(4); Cd–N(2), 2.246(4); Cd–N(3), 2.331(4); Cd–
O(2), 2.281(12); Cd–O(3), 2.344(10) for 4?CH2Cl2
.
H) = 75.0 Hz. The singlet at 8.95 ppm is assigned to Hb (3, 12) and
the other singlet at 7.26 ppm is due to Hb (17, 18) (Fig. 2a). In 4
at 20 °C, the doublet at 8.77 ppm is assigned to Hb (2, 13) with
3J(H–H) = 4.2 Hz and the other doublet at 8.71 ppm with 3J(H–
H) = 4.2 Hz is due to Hb (3, 12) (Fig. 3a). The singlet at 8.81 ppm
is assigned to Hb (7, 8) and the other singlet at 8.64 ppm is due
to Hb (17, 18) (Fig. 3a).
set of ortho protons, o-H (22, 32) [or o-H (26, 32)] and o-H (26,
28) [or o-H (22, 28)], for phenyl C(24) and C(30) and the other
set of ortho protons, o0-H (34, 40) [or o0-H (34, 44)] and o0-H (38,
44) [or o0-H (38, 40)] for phenyl C(36) and C(42) of 3 (or 4), respec-
tively. In 3 at 20 °C, the rotation of the phenyl group along C1–Cmeso
[C(5)–C(21) or C(10)–C(27)] bond is slow [9]. This slow rotation is
supported by the two doublets at 8.25 and 8.12 ppm due to o-H
(22, 32) and o-H (26, 28), respectively (Fig. 2a). Moreover, the rota-
tion of phenyl group along C(15)–C(33) [or C(20)–C(39)] bond for 3
is at the near fast exchange region [9]. In this fast exchange region,
the signals are observed as broad singlet at 8.47 ppm (Fig. 2a). At
ꢁ90 °C, both rotations are extremely slow. Hence, the rate of intra-
molecular exchange of the ortho protons for 3 in CD2Cl2 is also ex-
tremely slow. The singlet at 8.16 ppm and the doublet at 8.13 ppm
with 3J(H–H) = 5.4 Hz is assigned as ortho protons o-H (26) and o-H
(28). The two sets of signals at 8.27 and 8.20 ppm is due to ortho
protons o-H (22) and o-H (32) for 3 (Fig. 2b). Likewise, the two par-
tially overlapping doublets at 8.72 ppm with 3J(HꢁH) = 7.8 Hz is
The signal arising from the NH proton of 4 in CD2Cl2 was ob-
served as a singlet at d ꢁ0.99 ppm (
Dm1/2 = 13 Hz) at 20 °C. This
NMR data suggests that the NH protons of 4 undergo intermediate
intermolecular proton exchange with water at 20 °C. At low tem-
perature the chemical exchange slows down that allows the obser-
vation of a broad singlet for the NH proton at ꢁ1.08 ppm (
Dm1/
2 = 17 Hz) for 4 at ꢁ90 °C. In this case, the NH proton signal for 4
at ꢁ90 °C is broadened by the quadrupolar interaction of the 14N
nucleus.
Non-equivalence of the two sides of the macrocycle will cause
each phenyl ring have two distinct ortho resonances, with one

K.-T. Chen et al. / Inorganic Chemistry Communications 13 (2010) 506–510
509
Fig. 2. 1H NMR (599.95 MHz) spectra showing four different b-pyrrole protons Hb and phenyl protons (o-H, m,p-H) for 3 in CD2Cl2: (a) 20 °C and (b) ꢁ90 °C.
Fig. 3. 1H NMR (599.95 MHz) spectra showing four different b-pyrrole protons Hb and phenyl protons (o-H, m,p-H) for 4: (a) in CDCl3 at 20 °C and (b) in CD2Cl2 at ꢁ90 °C.
due to ortho protons o0-H (34, 40). The same two sets of signals at
protons of 4 in CDCl3 at 20 °C were observed as two sets of dou-
blets: one doublet at 8.65 ppm is assigned to ortho protons o-H
(26, 32) with 3J(H–H) = 6.6 Hz and the other doublet at 8.44 is
due to ortho protons o-H (22, 28) with 3J(H–H) = 6.6 Hz (Fig. 3a).
Likewise, two sets of broad singlet at 8.37 and 8.08 ppm is due to
ortho protons o0-H (34, 44) and o0-H (38, 40) (Fig. 3a). However,
for ortho protons of 4 in CD2Cl2 at ꢁ90 °C, the rotation of phenyl
group along C1–Cmeso bond in 4 is extremely slow, which is evident
from the appearance of the four doublets at 8.49 [o-H (26, 32)],
8.27 and 8.20 ppm is also due to ortho protons o0-H (38) and o0-H
(44) for 3 (Fig. 2b). The free energy of activation
D
G–293 ¼ 55:94 kJ/
mol is therefore, determined for the intramolecular exchange of
the ortho protons between o0-H (34, 40) and o0-H (38, 44) in 3.
In a similar fashion, the rotation of the phenyl group of 4 in
CDCl3 at 20 °C along C(10)–C(27) [or C(5)–C(21)] bond is slow
and the rotation along C(20)–C(39) [or C(15)–C(33)] is at the inter-
mediate exchange region [9]. Hence the 1H resonances for the ortho

510
K.-T. Chen et al. / Inorganic Chemistry Communications 13 (2010) 506–510
at this temperature, the methyl and carbonyl carbons of OAcꢁ are
observed at 17.5 ppm [with 3J(Tl–C) = 200 Hz] and 174.7 ppm [with
2J(Tl–C) = 204 Hz] as doublets, respectively [11].
8.42 [o-H (22, 28)], 8.31 and 8.04 ppm for o0-H (34, 44) and o0-H
(38, 40) due to four different ortho protons of the aromatic ring
in 4 (Fig. 3b).
Due to the ring current effect, upfield shifts for the 1H reso-
nances of (o-Cl)BA-Ph-H6, (o-Cl)BA-Ph-H3, (o-Cl)BA-Ph-H5 and
X-ray diffraction analysis unambiguously confirms that 3 and 4
have a chelating bidentate OAcꢁ ligand in the solid state. The 13C
NMR chemical shifts were shown to be a useful tool for diagnosing
the nature of acetate ligands, whether unidentate or bidentate in
diamagnetic complexes. Unidentate acetate ligands were located
at 20.5 0.2 and 168.2 1.7 ppm and bidentate acetate ligands at
18.0 0.7 and 175.2 1.6 ppm [13]. The methyl and carbonyl
chemical shifts of the acetate group in 3 (or 4) at 20 °C in CDCl3
are separately located at 18.5 (or 18.9) and 175.0 (or 176.4) ppm
confirming that the acetate is chelating bidentately and is coordi-
nated to the thallium (or cadmium) atom in 3 (or 4) in the solution
phase.
In conclusion, we have investigated two new, diamagnetic and
mononuclear porphyrin complexes, namely, a thallium(III) com-
plex 3ꢀ0.5H2O and a cadmium(II) complex 4ꢀCH2Cl2 and their X-
ray structures are established. In 3, the N–H bond of the o-chloro-
benzamido ligand is cleaved and the o-chlorobenzamido nitrogen
participates in bonding to the thallium ion. Complex 3 is a bridged
metalloporphyrins with a metal–N–N linkage. In 4, the (o-Cl)BA
substituent is left intact and the cadmium(II) ion is coordinated
to the four nitrogens [N(1)–N(4)] of the macrocycle core. Com-
(o-Cl)BA-Ph-H4 for 4 in CDCl3 at 20 °C are
D
d = ꢁ3.2 [from 7.77
(obtained from o-chlorobenzamide) to 4.57 ppm], ꢁ1.46 (from
7.42 to 5.96 ppm), ꢁ1.34 (from 7.35 to 6.01 ppm) and ꢁ1.08
(from 7.40 to 6.32 ppm), respectively. As the distance between
the geometrical center (Ct) of the 4N plane [i.e., N(1), N(2), N(3),
N(4) for 3 and 4] and axial protons gets smaller, the shielding ef-
fect becomes larger. In 4, the distance for Ctꢀ ꢀ ꢀ(o-Cl)BA-Ph-H6,
Ctꢀ ꢀ ꢀ(o-Cl)BA-Ph-H3, Ctꢀ ꢀ ꢀ(o-Cl)BA-Ph-H5 and Ctꢀ ꢀ ꢀ(o-Cl)BA-Ph-H4,
increases from 5.419, 6.284, 7.057 to 7.396 Å. As the (o-Cl)BA-
Ph-H6 proton of 4 is closer to Ct, the shielding gets larger for this
(o-Cl)BA-Ph-H6 protons. A similar ring current effect is also ob-
served for 3. The average distance between Ctꢀ ꢀ ꢀ(o-Cl)BA-Ph-H6,
Ctꢀ ꢀ ꢀ(o-Cl)BA-Ph-H5, Ctꢀ ꢀ ꢀ(o-Cl)BA-Ph-H3 and Ctꢀ ꢀ ꢀ(o-Cl)BA-Ph-H4
for 3 increases from 3.233, 4.866, 5.946 to 5.984 Å. The 1H NMR
spectra reveal that the aromatic protons of the (o-Cl)BA group ap-
pear as a doublet of triplets at 6.36 ppm [(o-Cl)BA-Ph-H4], a dou-
blet at 6.21 ppm [(o-Cl)BA-Ph-H3], the triplet at 6.10 ppm [(o-
Cl)BA-Ph-H5] and the other doublet at 4.87 ppm [(o-Cl)BA-Ph-
H6] for 3. The (o-Cl)BA bonding argument is further supported
by the result that at 20 °C in 13C NMR the (o-Cl)BA-Ph-C1 [i.e.,
C(46)] and the C(45) peaks in 3 were observed at 132.6 ppm with
3J(Tl–C) = 20.1 Hz and at 167.7 ppm with 2J(Tl–C) = 665 Hz,
respectively.
pound
4 is a cadmium(II) N-substituted-N-aminoporphyrin
complex.
Acknowledgments
The 1H NMR spectrum for OAcꢁ of 4 in CD2Cl2 displays a sharp
The financial support from the National Research Council of the
ROC under Grant NSC 98-2113-M-005-005 is gratefully acknowl-
edged. We thank Dr. S. Elango for helpful discussions.
singlet for CH3 at d0.06 ppm with
a sharp singlet for the same methyl proton at d ꢁ0.01 ppm with
1/2 = 4 Hz at ꢁ90 °C. This minimum deviation in the value of line
width (
1/2) upon cooling indicates that OAcꢁ exchange does not
Dm1/2 = 3 Hz at 20 °C and remains
D
m
D
m
occur in compound 4.
Appendix A. Supplementary material
Upon cooling of a 0.02 M CD2Cl2 solution of 3, the methyl pro-
ton signal of OAcꢁ, being a single peak at 20 °C (d 0.17 ppm), first
broadened (coalescence temperature Tc = ꢁ75 °C) and then split
into peaks with a separation of 14.4 Hz at d 0.08 ppm at ꢁ90 °C.
As the exchange of OAcꢁ within 3 is reversible, the results at
599.95 MHz confirm the separation as a coupling of 4J(Tl–H) rather
than a chemical shift difference [10,11]. The most likely cause of
loss of coupling is due to the reversible dissociation of acetate with
a small dissociation constant.
CCDC 695921 (for 3ꢀ0.5H2O) and 695922 (4ꢀCH2Cl2) contain the
supplementary crystallographic data for this paper. These data can
be obtained free of charge from The Cambridge Crystallographic
Data Centre via www.ccdc.cam.ac.uk/data_request/cif. Supplemen-
tary data associated with this article can be found, in the online
version, at doi:10.1016/j.inoche.2010.01.022.
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Collins College Publishers, New York, 1993. pp. 114, 292.
[4] Y. Zhang, Inorg. Chem. 21 (1982) 3886.
[5] Y. Zhang, Inorg. Chem. 21 (1982) 3889.
[6] F.A. Yang, J.H. Chen, H.Y. Hsieh, S. Elango, L.P. Hwang, Inorg. Chem. 42 (2003)
4603.
CD2Cl2
*
)
TlðN-NCOðo-ClÞC6H4-tppÞþ þ OAcꢁ
ð1Þ
Such a scenario would lead to the change in the chemical shift with
temperature and no detectable free OAcꢁ and Tl(N-NCO(o-Cl)C6H4-
tpp)+ at low temperature, but would lead to the loss of coupling be-
tween acetate and thallium at higher temperature [10–12]. The
chemical shift in the high-temperature limit is the average of the
two species (i.e., Tl(N-NCO(o-Cl)C6H4-tpp)(OAc) and OAcꢁ) in Eq.
(1) weighted by their concentration. The free energy of activation
[7] J.Y. Tung, J.H. Chen, Polyhedron 26 (2007) 589.
[8] M. Ravikanth, T.K. Chandrashekar, Struct. Bond. 82 (1995) 105.
[9] R.S. Drago, Physical Methods for Chemists, second ed., Saunder College
Publishing, New York, 1992. pp. 290–295.
[10] J.Y. Tung, J.I. Jang, C.C. Lin, J.H. Chen, L.P. Hwang, Inorg. Chem. 39 (2000) 1106.
[11] F.A. Yang, K.Y. Cho, J.H. Chen, S.S. Wang, J.Y. Tung, H.Y. Hsieh, F.L. Liao, G.H. Lee,
L.P. Hwang, S. Elango, Polyhedron 25 (2006) 2207.
[12] J.P. Jenson, E.L. Muetteries, in: L.M. Jackman, F.A. Cotton (Eds.), Dynamic
Nuclear Magnetic Resonance Spectroscopy, Academic Press, New York, 1975,
pp. 299–304.
at the coalescence temperature Tc for the intermolecular exchange
–
of OAcꢁ in 3 is determined to be
D
G198 ¼ 42:1 kJ/mol. At 20 °C,
intermolecular exchange of the OAcꢁ group for 3 is rapid as indi-
cated by the appearance of singlet signals due to carbonyl carbons
at 175.0 ppm and methyl carbons at 18.5 ppm. At ꢁ90 °C, the rate
of intermolecular exchange of OAcꢁ for 3 in CD2Cl2 is slow. Hence,
[13] S.J. Lin, T.N. Hong, J.Y. Tung, J.H. Chen, Inorg. Chem. 36 (1997) 3886.