Salicylate exchange in meso-tetraphenylporphyrinato salicylato thallium (III), Tl (tpp) (2-OH-C6H4CO2) and 13C NMR investigation of its homolog thiocyanato (meso-tetra-p-tolyl-porphyrinato)thallium (III), Tl (tptp) (SCN)

Article abstract of DOI:10.1016/S0277-5387(98)00277-0

This work determines the crystal structure of meso-tetraphenylporphyrinato salicylato thallium (III)S> Tl (tpp) (2-OH-C₆H₄CO₂) (or Tl (tpp) (SA)) The coordination sphere of the Tl³ ion is an approximately square-based pyramid in which a chelating bidentate 2-OH-C₆H₄CO^-₂ group occupies the apical site The average Tl (1)-N bond distance is 2221 A and the Tl atom is displaced 076 A from the porphyrin plane The Tl (1)-O(1) and Tl (1)-O(2) distance are 236 (1) and 247 (1) AS> respectively Variable temperature ¹³C NMR measurements reveal that the salicylato group of Tl (tpp) (SA) in CD₂Cl₂ solvent undergoes a ligand exchange In the slow exchange regionS> the carbonyl and C_1″ carbons of the salicylato group are separately located at 1696 ppm [with a ²J (Tl- ¹³C) coupling constant of 157 Hz] and 1115 ppm [with a ³J (Tl- ¹³C) coupling constant of 180 Hz] for Tl (tpp) (SA) in CD₂Cl₂ at -90°C In the fast exchange regionS> the C*O and C_1″ carbons of the 2-OH-C₆H₄CO^-₂ ligand in CD₂Cl₂ at 24°C are singlets at 1698 and 1125 ppmS> respectively The ¹³C resonance of the axial isocyanato ligand in the compound thiocyanato (meso-tetra-p-tolyl-porphyrinato)thallium (III)S> Tl (tptp) (SCN)S> was observed at 1107 ppm (24°C) with ²J (Tl- ¹³C) coupling constant 253 Hz This finding suggests that thiocyanato group isS> as thiocyanate typeS> axially coordinated to the Tl atom in Tl (tptp) (SCN) In additionS> there is no SCN ^- exchange in the same compound.

Full text of DOI:10.1016/S0277-5387(98)00277-0

\
Polyhedron 07 "0888# 034Ð049
PERGAMON
Salicylate exchange in meso!tetraphenylporphyrinato salicylato
thallium"III#\ Tl"tpp#"1!OH!C5H3CO1# and 02C NMR investigation of
its homolog thiocyanato "meso!tetra!p!tolyl!
porphyrinato#thallium"III#\ Tl"tptp#"SCN#
Yunn!Yu Lua\ Jo!Yu Tunga\ Jyh!Horung Chena\ ꢀ\ Feng!Ling Liaob\ Sue!Lein Wangb\
Shin!Shin Wangc\ Lian!Pin Hwangd
aDepartment of Chemistry\ National Chung!Hsing University\ Taichung 39116\ Taiwan
bDepartment of Chemistry\ National Tsing!Hua University\ Hsing!Chu 29932\ Taiwan
cUnion Chemical Laboratories\ Hsin!Chu 29932\ Taiwan
dDepartment of Chemistry\ National Taiwan University and Institute of Atomic and Molecular Sciences\ Academia Sinica\ Taipei 09653\ Taiwan
Received 02 May 0887^ accepted 09 July 0887
Abstract
This work determines the crystal structure of meso!tetraphenylporphyrinato salicylato thallium"III#\ Tl"tpp#"1!OH!C5H3CO1#"or
Tl"tpp#"SA##[ The coordination sphere of the Tl2¦ ion is an approximately square!based pyramid in which a chelating bidentate 1!
OH!C5H3CO−1 group occupies the apical site[ The average Tl"0#ÐN bond distance is 1[110 A and the Tl atom is displaced 9[65 A
Ä
Ä
Ä
from the porphyrin plane[ The Tl"0#ÐO"0# and Tl"0#ÐO"1# distance are 1[25"0# and 1[36"0# A\ respectively[ Variable temperature
02C NMR measurements reveal that the salicylato group of Tl"tpp#"SA# in CD1Cl1 solvent undergoes a ligand exchange[ In the slow
exchange region\ the carbonyl and C0ý carbons of the salicylato group are separately located at 058[5 ppm ðwith a 1J"TlÐ02C# coupling
constant of 046 HzŁ and 000[4 ppm ðwith a 2J"TlÐ02C# coupling constant of 079 HzŁ for Tl"tpp#"SA# in CD1Cl1 at −89>C[ In the fast
exchange region\ the CꢀO and C0ý carbons of the 1!OH!C5H3CO−1 ligand in CD1Cl1 at 13>C are singlets at 058[7 and 001[4 ppm\
respectively[ The 02C resonance of the axial isocyanato ligand in the compound thiocyanato "meso!tetra!p!tolyl!por!
1
phyrinato#thallium"III#\ Tl"tptp#"SCN#\ was observed at 009[6 ppm "13>C# with J"TlÐ02C# coupling constant 142 Hz[ This _nding
suggests that thiocyanato group is\ as thiocyanate type\ axially coordinated to the Tl atom in Tl"tptp#"SCN#[ In addition\ there is
no SCN− exchange in the same compound[ Þ 0888 Elsevier Science Ltd[ All rights reserved[
Keywords] Crystal structure^ Thallium porphyrin complexes^ cis geometries^ Salicyato ligand^ Low temperature 02C NMR analysis^ Ligand exchange
0[ Introduction
Tl"tpp#"SCN#\ and meso!tetra"3!methoxyphenylpor!
phyrinato#thiocyanatothallium"III#\ Tl"tmpp#"SCN#[
Both complexes are thallium "III# complexes with the
thiocynate\ SCN−\ being unidentately coordinated to Tl
atom[ When replacing the tpp and tmpp with meso!tetra!
p!tolyl!porphyrin "tptp#\ they became thiocyanato "meso!
Our earlier work reported on the benzoate exchange
in benzoato meso!tetra"3!methoxyphenylporphyrin!
ato#thallium"III#\ Tl"tmpp#"C5H4CO1# ð0Ł[ When replac!
ing C5H4CO−1 with the salicylate group\ 1!OH!C5H3CO−1 \
and replacing tmpp with tpp\ the complex
tetra!p!tolyl!porphyrinato#
thallium"III#\
Tl"tptp#
"SCN#"1#[ That investigation also reported on the
synthesis\ 02C and 0H NMR spectroscopic studies of the
new complex "1#[ The 02C signal of SCN− unam!
biguously solve the dichotomy of thiocyanate vs iso!
thiocyanate binding to the thallium centre[
Tl"tmpp#"C5H4CO1#
became
meso!tetraphenyl!
porphyrinato salicylato thallium"III#\ Tl"tpp#"1!OH!
C5H3CO1# "0# ðor Tl"tpp#"SA#Ł[ The benzoato exchange
of Tl"tmpp#"C5H4CO1# encourages us to investigate a
similar salicylato exchange for Tl"tpp#"SA#[
In the light of above discussion\ this work performs
0H and X!ray analysis of 0[ The 02C NMR spectra at a
low temperature are examined to infer the apical ligand\
1!OH!C5H3CO−1 \ exchange for 0 in CD1Cl1[ In addition\
the exchange for cis bidentately 5!coordinate thal!
In a related work\ Senge et al[ ð1Ł reported on meso!
tetraphenylporphyrinato
thiocyanatothallium"III#\
ꢀ Corresponding author[
9166!4276:88:, ! see front matter Þ 0888 Elsevier Science Ltd[ All rights reserved[
PII] S9166!4276 "87#99166!9

035
Y[!Y[ Lu et al[ : Polyhedron 07 "0888# 034Ð049
Table 0
lium"III# complex "0# is compared with the no exchange!
able axial ligand for monodentately 4!coordinate
thallium "III# complex "1#[
Crystal data for Tl"tpp#"SA#=H1O
Formula
C40H24N3O3Tl
861[1
Formula weight
Ä
a "A#
00[0081"2#
02[3736"2#
04[5916"3#
57[889"0#
60[275"0#
72[683"0#
1958[5"5#
1
1[ Experimental
Ä
b "A#
Ä
c "A#
a ">#
b ">#
g ">#
1[0[ Preparation of Tl"tpp#"SA# "0#
Tl"tpp#Cl "033[2 mg\ 9[04 mmol# in CHCl2 "29 cm2# was
treated with sodium salicylate "89[0 mg\ 9[45 mmol# in
CH2OH "14 cm2# and stirred under re~ux for 01 h[ After
concentration\ the mixture was dissolved in CH1Cl1 and
extracted four times with distilled water to remove excess
sodium salicylate[ The CH1Cl1 layer was then con!
centrated to dryness\ producing a purple prism "037[1 mg\
80[4)#[ Next\ the crystals were grown by di}usion of
ether vapour into a CH1Cl1 solution[ This crystal was
2
Ä
V "A #
Z
Dc "g cm−2
#
0[459
¹
Space group
P0
F"999#
853
28[43
4[08)
4[21)
m "cm−0
#
Ra
b
Rw
GOF
0[94
Ab
0
Bb
0[4×09−2
9[21×9[39×9[49
19589
0
dissolved in CDCl2 "or CD1Cl1# for H and 02C NMR
Crystal size "mm2#
Data collected
1umax ">#
0
Table 2 measurements at 13>C[ H NMR d"ppm#] 8[96
3
"d\ J"TlÐH#ꢁ56 Hz\ b!pyrrole H#\ 7[27 "s# and 7[05 "s#
46[6
for H1\5\ 6[79 "s# and 6[68 "s# for H2\4\ 6[65 "s# for H3\ 5[67
"t\ 2J"HÐH#ꢁ6[5 Hz\ H3ý#\ 5[10 "d\ 2J"HÐH#ꢁ7[1 Hz\
H2ý#\ 5[05 "d\ 2J"HÐH#ꢁ7[9 Hz\ H5ý#\ 5[97 "t\ 2J"HÐ
H#ꢁ6[4 Hz\ H4ý#[
Temperature "K#
Data used
Discrimination
185
5069 "Rintꢁ9[9615#
I×2s"I#
a RꢁðS==Fo=−=Fc==:S=Fo=Ł[
b RwꢁðSw"==Fo=−=Fc==#1:Sw"=Fo=#1Ł0:1^ wꢁA:"s1Fo¦BF1o#[
1[1[ Preparation of Tl"tptp#"SCN# "1#
Compound 1 was prepared by substituting sodium sal!
icylate with KSCN "50[1 mg\ 9[52 mmol# and Tl"tpp#Cl
with Tl"tptp#Cl "056[3 mg\ 9[07 mmol# in the preparation
of 0[ Purple crystals "1# "032[8 mg\ 74[5)# were obtained[
This crystal was dissolved in CDCl2 for 0H and 02C NMR
equivalent re~ections using the SHELXTL!PC program
package with "Tmin\maxꢁ9[263\ 9[817#[ The structures were
solved by direct methods "SHELXTL PLUS# and re_ned
by full!matrix least!squares[ All non!hydrogen atoms
were re_ned with anisotropic thermal parameters\
whereas all hydrogen!atom positions were located on
a di}erence map and included in the structure factor
calculation[ Table 1 lists selected bond distances and
angles for Tl"tpp#"SA#=H1O[
0
Table 2 measurements at 13>C[ H NMR d"ppm#] 8[06
"d\ 3J"TlÐH#ꢁ59 Hz\ b!pyrrole H#\ 7[21 "d\ 2J"HÐ
H#ꢁ6[3 Hz# and 7[95 "d\ 2J"HÐH#ꢁ6[1 Hz# for H1\5\ 6[53
"d\ 2J"HÐH#ꢁ6[5 Hz# and 6[44 "d\ 2J"HÐH#ꢁ6[5 Hz# for
H2\4\ 1[60 "s\ CH2#[
1[2[ NMR spectra
2[ Results and discussion
0H and 02C spectra in CDCl2 "or CD1Cl1# were rec!
orded at 399[02 "or 599[05# and 099[50 "or 049[81# MHz\
respectively\ on a Bruker AM!399 "or Bruker DMX!599#
2[0[ Molecular structure of ðTl"tpp#"SA#=H1OŁ
Figure 0 illustrates the skeletal framework of complex
0
spectrometers at 13 and −89>C[ H and 02C NMR are
¹
Tl"tpp#"SA#=H1O with P0 symmetry[ This framework has
relative to CDCl2 "or CD1Cl1# at 6[13 "or 4[29 ppm# and
the central line of CDCl2 "or CD1Cl1# at 66[9 "or
42[5 ppm#\ respectively[
a cis six!coordinate thallium with four nitrogen atoms of
the porphyrinato group and the asymmetric bidentate
1!OH!C5H3CO−1 ligand[ Bond distances "A# are Tl"l#Ð
Ä
O"l#ꢁ1[25"0#\ Tl"l#ÐO"1#ꢁ1[36"0#\ O"1#ÐC"40#ꢁ0[29"1#\
Ä
1[3[ Crystallography
O"0#ÐC"40#ꢁ0[04"1#\ C"49#ÐC"40#ꢁ0[46"1# A and the
Ä
mean Tl"0#ÐNꢁ1[110"7# A[ The geometrical con!
Table 0 lists the crystal data and other information
for Tl"tpp#"SA#=H1O[ Measurements were taken on a
Siemens SMART CCD di}ractometer using mono!
chromatic MoKa radiation "lꢁ9[60962 A#[ Next\
absorption corrections were based on 6916 symmetry!
_guration around the Tl2¦ ion is an approximately
square!based pyramid in which an asymmetric "chel!
ating# bidentate 1!OH!C5H3CO−1 group occupies the api!
cal site[ The dihedral angles between the mean plane of
the skeleton "C19N3# and the planes of the phenyl group
Ä

Y[!Y[ Lu et al[ : Polyhedron 07 "0888# 034Ð049
036
Table 1
Selected bond distance "A# and angle "># for Tl"tpp#"SA#=H1O
Ä
Tl"0#ÐO"0#
Tl"0#ÐO"1#
O"1#ÐC"40#
O"0#ÐC"40#
C"49#ÐC"40#
1[25"0#
1[36"0#
0[29"1#
0[04"1#
0[46"1#
Tl"0#ÐN"0#
Tl"0#ÐN"1#
Tl"0#ÐN"2#
Tl"0#ÐN"3#
C"38#ÐO"2#
1[114"5#
1[129"5#
1[102"6#
1[106"7#
0[36"1#
O"0#ÐTl"0#ÐN"0#
O"0#ÐTl"0#ÐN"1#
O"0#ÐTl"0#ÐN"2#
O"0#ÐTl"0#ÐN"3#
N"0#ÐTl"0#ÐN"1#
N"0#ÐTl"0#ÐN"2#
N"0#ÐTl"0#ÐN"3#
O"0#ÐTl"0#ÐO"1#
76[3"2#
002[8"2#
020[7"2#
090[5"2#
72[0"1#
039[4"2#
72[7"2#
42[3"2#
O"1#ÐTl"0#ÐN"0#
O"1#ÐTl"0#ÐN"1#
O"1#ÐTl"0#ÐN"2#
O"1#ÐTl"0#ÐN"3#
N"1#ÐTl"0#ÐN"2#
N"1#ÐTl"0#ÐN"3#
N"2#ÐTl"0#ÐN"3#
O"1#ÐC"40#ÐO"0#
017[5"2#
73[6"2#
75[8"2#
029[6"2#
73[0"1#
030[3"2#
72[3"2#
015"0#
Fig[ 0[ Molecular con_guration and atom!labeling scheme for Tl"tpp#"SA#=H1O\ with ellipsoids drawn at 29) probability[ Hydrogen atoms except
H"2A# are omitted for clarity[ Solvent is O"3#H"3A#H"3B#[
are 55[2> ðC"13#Ł\ 78[5> ðC"29#Ł\ 78[1> ðC"25#Ł\ and 57[0>
ðC"31#Ł[ The Tl atom lies 9[65 A from the 13!atom por!
phyrin plane "C19N3#[ The central hole|s radii "Ct?ÐN[ The
distance from the geometrical centre "Ct?# of the mean
plane of the 13!atom core to the porphyrinato!core N
Ä
Ä
Ä
atoms# is 1[983 A which is larger than 1[90 A suggested
by Collin et al[ ð2Ł[ The thallium"III# atom is bonded in
a highly expanded porphyrinato core "C19N3# and the

037
Y[!Y[ Lu et al[ : Polyhedron 07 "0888# 034Ð049
distortion of the porphyrin "C19N3 and Tl# can be viewed
as a domed shape[
The observed H"2A#===O"1# and O"1#===O"2# distances
Ä
are 0[792 and 1[516 A\ respectively[ These distances are
shorter than those expected from the van der Waals dis!
Ä
tances "1[59 and 1[79 A\ respectively#[ The O"2#ÐH"2A#Ð
O"1# angle is 042[6> and its deviation from linearity is not
too severe[ Therefore\ an intramolecular hydrogen bond
exists between H"2A# and the O"1# atom[
0
2[1[ 02C and H NMR for Tl"tpp#"SA# "0# in CD1Cl1
and Tl"tptp#"SCN# "1# in CDCl2 solution
Figure 1 depicts the representative broad band 02C
spectra of 0 in CD1Cl1 solvent at 13 and −89>C\ respec!
tively[ Table 2 summarizes their 02C data[ At 13>C\ the
exchange of the 1!OH!C5H3CO−1 group is rapid\ indicated
by singlet signals arising from carbonyl carbons at
058[7 ppm and C0ý carbons at 001[4 ppm shown in Fig[
1"a#[ At −89>C\ the rate of the exchange of 1!OH!
C5H3CO−1 for 0 in CD1Cl1 is slower than the coupling
frequency of TlÐ02C\ i[e[ 058201 Hz[ Hence\ CꢀO and
C0ý carbons of 1!OH!C5H3CO−1 ðFig[ 1"b#Ł are observed
1
at 058[5 ppm ðwith J"TlÐ02C#ꢁ046 HzŁ and 000[4 ppm
ðwith 2J"TlÐ02C#ꢁ079 HzŁ\ respectively[
The exchange of the 1!OH!C5H3CO−1 group is rapid
for "0# in CD1Cl1 at 13>C[ Whereas the rotation of phenyl
group along C0ÐCmeso bond is slow at the same tem!
perature on the NMR time!scale[ This slow rotation is
supported by assigning 023[8\ 023[1 ppm to the C1\5 car!
bons Table 2 and by assigning 7[27\ 7[05 ppm to H1\5
protons "or ortho!H#[
Owing to the ring current e}ect\ up_eld shifts for the
0H resonances of H5ý\ H4ý\ H2ý and H3ý in "0# are −0[48
ðfrom 6[64 "obtained from salicylic acid# to 5[05 ppmŁ\
−9[79 " from 5[77 to 5[97 ppm#\ −9[56 " from 5[77 to
5[10 ppm# and −9[57 " from 6[35 to 5[67 ppm#\ respec!
tively[ As the H5ý proton approaches the Ct?\ the shielding
becomes larger[
Isothiocyanate "!Nꢀ1C1S# carbon nuclei resonate
between 019 and 029 ppm[ Typical nitrile shift values
"009Ð004 ppm# are characteristic of thiocyanates "!SꢀÐ
C2N# ð3Ł[ The doublet signals for the SCN− carbons at
009[6 ppm
with
1J"TlÐ02C#ꢁ142 Hz
for
Tl"tptp#"SCN#"1# in CDCl2 at 13>C "Table 2# indicate
that SꢀCN− exchange does not occur in compound "1#[
The thiocyanate might be\ as in the case of Tl"tpp#"SCN#
and Tl"tmpp#"SCN#\ unidentately coordinated to the Tl
atom for compound "1#[ Interestingly\ ligands "X# such
as CN− ð4Ð6Ł\ SCN−\ CH−2 ð7Ł that are unidentately and
cis 4!coordinate bonded to Tl atom in Tl"por#X turn out
not to be exchangeable[ However\ the chelating bidentate
ligands "L# such as OAc− ð6\8\09Ł\ C5H4COO− ð0\00Ł\
CF2COO− ð01Ł\ SA− in Tl"por#L undergo either intra!
molecular or intermolecular ligand exchange[

Y[!Y[ Lu et al[ : Polyhedron 07 "0888# 034Ð049
038
Fig[ 1[ 02C broad band NMR spectra for Tl"tpp#"SA# in CD1Cl1 "a# at 13>C "099[50 MHz# and "b# at −89>C "049[81 MHz#[
2[2[ The relative magnitude of mesomeric\ inductive and
intramolecular hydrogen bond effects on chelating biden!
tate and cis 5!coordinate complex\ Tl"tpp#L\ with
LꢀOAc−\ C5H4COO−\ CF2COO−\ and SA−
action decreases electron de_ciency at the carbonyl car!
bon in Tl"tpp#"C5H4COO#[ The up_eld shift of
−06[3 ppm for carbonyl carbons from Tl"tpp#"OAc# ð8Ł
to Tl"tpp#"CF2COO# "at 046[4 ppm# ð01Ł is ascribed to
the inductive e}ect originating from the electronegative
~uorine atoms[ Moreover\ the down_eld shift of 0[2 ppm
for the same carbons from Tl"tpp#"C5H4COO# ð00Ł to
Tl"tpp#"SA# "at 058[7 ppm# is attributed to the intra!
molecular hydrogen bond in 0[
The mesomeric e}ect can account for the up_eld shift
of −5[3 ppm for carbonyl carbons from Tl"tpp#"OAc#
"at 063[8 ppm# ð8Ł to Tl"tpp#"C5H4COO# "at 057[4 ppm#
ð00Ł[ This is owing to the fact that the mesomeric inter!

049
Y[!Y[ Lu et al[ : Polyhedron 07 "0888# 034Ð049
ð3Ł Breitmaier E\ Voelter W[ Carbon!02 NMR Spectroscopy\ 2rd edn[
Acknowledgements
New York] VCH publishers\ 0889]134[
ð4Ł Lee WB\ Suen SC\ Tong TT\ Hong FE\ Chen JH[ J[ Organomet[
Chem[ 0882^349]52[
ð5Ł Cheng TW\ Chen YJ\ Hong FE\ Chen JH\ Wang SL\ Hwang LP[
Polyhedron 0883^02]392[
The authors would like to thank the National Science
Council of the Republic of China for _nancially sup!
porting this work under Contract No[ NSC 76!1002!M!
994!990[
ð6Ł Sheu YH\ Hong TN\ Lin CC\ Chen JH\ Wang SS[ Polyhedron
0886^05]570[
ð7Ł Tang SS\ Sheu MT\ Lin YH\ Liu IC\ Chen JH\ Wang SS[ Poly!
hedron 0884^03]290[
ð8Ł Chen JC\ Jang HS\ Chen JH\ Hwang LP[ Polyhedron
0880^09]1958[
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