Structural investigations on diorgano- and triorganotin(IV) derivatives of [meso-tetra(4-sulfonatophenyl)porphine] metal chlorides

Article abstract of DOI:10.1016/j.jorganchem.2005.12.012

Several new complexes of organotin(IV) moieties with MCl _n[meso-tetra(4-sulfonatophenyl)porphine], (R₂Sn) ₂MCl_n[meso-tetra(4-sulfonatophenyl)-porphinate]s and (R₃Sn)₄MCl_n [meso-tetra(4-sulfonatophenyl) porphinate]s, [M = Fe(III), Mn(III): n = 1, R = Me, n-Bu; Ph; M = Sn(IV): n = 2, R = Me, n-Bu] have been synthesized and their solid state configuration investigated by infrared (IR) and M?ssbauer spectroscopy, and by ¹H and ¹³C NMR in D₂O. The electron density on the metal ion coordinated inside the porphyrin ring is not influenced by the organotin(IV) moieties bonded to the oxygen atoms of the side chain sulfonatophenyl groups, as it has been inferred on the basis of M?ssbauer spectroscopy and, in particular, from the invariance of the isomer shift of the Fe(III) and Sn(IV) atoms coordinated into the porphyrin square plane of the newly synthesized complexes, with respect to the same atoms in the free ligand. As far as the coordination polyhedra around the peripheral tin atoms are concerned, infrared spectra and experimental M?ssbauer data would suggest octahedral and trigonal bipyramidal environments around tin, in polymeric configurations obtained, respectively, in the diorganotin derivatives through chelating or bridging sulfonate groups coordinating in the square plane, and in triorganotin(IV) complexes through bridging sulfonate oxygen atoms in axial positions. The structures of the (Me₃Sn)₄Sn(IV)Cl ₂[meso-tetra(4-sulfonatophenyl)porphinate] and of the two model systems, Me₃Sn(PS)(HPS) and Me₂Sn(PS)₂ [HPS = phenylsulfonic acid], have been studied by a two layer ONIOM method, using the hybrid DFT B3LYP functional for the higher layer, including the significant tin environment. This approach allowed us to support the structural hypotheses inferred by the IR and M?ssbauer spectroscopy analysis and to obtain detailed geometrical information of the tin environment in the compounds investigated. ¹H and ¹³C NMR data suggested retention of the geometry around the tin(IV) atom in D₂O solution.

Full text of DOI:10.1016/j.jorganchem.2005.12.012

Journal of Organometallic Chemistry 691 (2006) 1573–1583
www.elsevier.com/locate/jorganchem
Structural investigations on diorgano- and triorganotin(IV)
derivatives of [meso-tetra(4-sulfonatophenyl)porphine] metal chlorides
a
a
a
b
a
a
C. Pellerito , M. Scopelliti , T. Fiore , L. Nagy , G. Barone , M. Abbate ,
a
a,
*
G.C. Stocco , L. Pellerito
a
`
Dipartimento di Chimica Inorganica e Analitica ‘‘Stanislao Cannizzaro’’, Universita di Palermo, Viale delle Scienze, Parco d’Orleans II,
90128 Palermo, Italy
Department of Inorganic and Analytical Chemistry, University of Szeged, P.O. Box 440, H-6701 Szeged, Hungary
b
Received 7 December 2005; accepted 7 December 2005
Available online 19 January 2006
Abstract
Several new complexes of organotin(IV) moieties with MCln[meso-tetra(4-sulfonatophenyl)porphine], (R2Sn)2MCln[meso-tetra(4-sulf-
onatophenyl)-porphinate]s and (R3Sn)4MCln [meso-tetra(4-sulfonatophenyl)porphinate]s, [M = Fe(III), Mn(III): n = 1, R = Me, n-Bu;
Ph; M = Sn(IV): n = 2, R = Me, n-Bu] have been synthesized and their solid state configuration investigated by infrared (IR) and Mo¨ss-
1
bauer spectroscopy, and by H and 13C NMR in D2O.
The electron density on the metal ion coordinated inside the porphyrin ring is not influenced by the organotin(IV) moieties bonded to
the oxygen atoms of the side chain sulfonatophenyl groups, as it has been inferred on the basis of Mo¨ssbauer spectroscopy and, in par-
ticular, from the invariance of the isomer shift of the Fe(III) and Sn(IV) atoms coordinated into the porphyrin square plane of the newly
synthesized complexes, with respect to the same atoms in the free ligand.
As far as the coordination polyhedra around the peripheral tin atoms are concerned, infrared spectra and experimental Mo¨ssbauer
data would suggest octahedral and trigonal bipyramidal environments around tin, in polymeric configurations obtained, respectively, in
the diorganotin derivatives through chelating or bridging sulfonate groups coordinating in the square plane, and in triorganotin(IV)
complexes through bridging sulfonate oxygen atoms in axial positions.
The structures of the (Me3Sn)4Sn(IV)Cl2[meso-tetra(4-sulfonatophenyl)porphinate] and of the two model systems, Me3Sn(PS)(HPS)
and Me2Sn(PS)2 [HPS = phenylsulfonic acid], have been studied by a two layer ONIOM method, using the hybrid DFT B3LYP func-
tional for the higher layer, including the significant tin environment. This approach allowed us to support the structural hypotheses
inferred by the IR and Mo¨ssbauer spectroscopy analysis and to obtain detailed geometrical information of the tin environment in
the compounds investigated.
1H and 13C NMR data suggested retention of the geometry around the tin(IV) atom in D2O solution.
Ó 2005 Elsevier B.V. All rights reserved.
Keywords: Organotin(IV); Porphinate; Infrared; Mo¨ssbauer; DFT calculations; 1H and 13C NMR
1. Introduction
porphyrins, only few papers dealt with side chain deriva-
tives of metallic or organometallic moieties. Bis[diorgano-
tin(IV)chloro]-protoporphyrin IX complexes have been
investigated in the solid and in solution phase [1], and chro-
mosome damages have been evidenced in early-developing
embryos of Anilocra physodes L. (Crustacea, Isopoda) fol-
lowing exposure to bis(dimethyltin(IV)chloro)-protopor-
phyrin IX [2]. Fifteen side chain platinum(II)-porphyrin
In the recent past, in spite of the number of publications
which appeared in the literature on the chemistry of metal
*
Corresponding author. Tel.: +39 091 590367; fax: +39 091 427584.
E-mail address: bioinorg@unipa.it (L. Pellerito).
0022-328X/$ - see front matter Ó 2005 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2005.12.012

1574
C. Pellerito et al. / Journal of Organometallic Chemistry 691 (2006) 1573–1583
complexes have been synthesized, chemically characterized
and their antitumor activity in vivo towards MDA-MB 231
mammary carcinoma cell line tested [3].
SO3H
HO3S
A series of mono-, bis- and tetrakisporphyrin assemblies
have been prepared, by Yuan et al. [4], from interaction of
Zn(II)[5-(p-pyridyl)-10,15,20-triphenylporphyrinate] and
Zn(II)[5-(p-pyridyl)-10,15,20-tri(p-tolyl)porphyrinate] with
trans-Pd(DMSO)2Cl2 and cis-Pt(DMSO)2Cl2. In all the
synthesized complexes, both Pd and Pt were side chain
coordinated to the nitrogen donor atom of the pyridyl
groups [4].
N
Cl
N
N
M
N
[meso-Tetra(4-carboxyphenyl)porphine]
(=H6TPPC)
and [meso-tetra(4-sulfonatophenyl) porphine] (=H6TPPS)
interaction with diorgano and triorganotin(IV) moieties
have been investigated and the obtained results evidenced
the formation of complexes with formula (R2Sn)2H2-
TPPC, (R3Sn)4H2TPPC, (R2Sn)2H2TPPS and (R3Sn)4H2-
TPPS (R = Me, n-Bu, Ph), respectively. Their solid state
and solution configurations were reported, together with
their in vivo cytotoxic activity [5,6]. Stepwise assembly
of unsymmetrical supramolecular arrays containing
meso-40-pyridylphenylporphyrins and ruthenium coordi-
nation compounds, have been reported [7,8]. Recently, a
paper dealing with diorganotin(IV) and triorganotin(IV)
derivatives of chlorin-e6 (organo = Me, n-Bu, Ph), their
effect on sea urchin embryonic development and induced
apoptosis, has been published [9]. Finally, in order to
examine the pathway with which (Bu2Sn)2TPPS and
(Bu3Sn)4TPPS induced A375 cell death, DNA fragmenta-
tion analysis, Annexin V binding and PI uptake as well as
caspases activation analysis by Western blot, were carried
out [10].
HO3S
HO3S
SO3H
SO3H
a
N
Cl
N
N
Sn
N
Cl
In the present paper, investigations have been extended
to di- and triorganotin(IV) complexes of meso-tetra(4-sulf-
onatophenyl)porphine derivatives, containing Fe(III)Cl,
Mn(III)Cl or Sn(IV)Cl2 groups within the porphyrin ring
(Fig. 1a and b).
HO3S
SO3H
b
Fig. 1. M(III)Cl[meso-tetra(4-sulfonatophenyl)porphine], [M = Fe(III),
Mn(III)] (a); Sn(IV)Cl2[meso-tetra(4-sulfonatophenyl)porphine] (b).
2.1.1. (R2Sn)2MCln[meso-tetra(4-sulfonatophenyl)-
porphinate]s, [M = Fe(III), Mn(III): n = 1, R = Me,
n-Bu; Ph; M = Sn(IV): n = 2, R = Me, n-Bu]
2. Experimental
2.1. Chemical materials and methods
MClnH4[meso-tetra(4-sulfonatophenyl)porphine]
and
the appropriate (R2Sn)2O, suspended in 50 ml of CH3OH,
in the 1:2 stoichiometric ratio, were allowed to react for
24 h at about 40 °C, under a constant stirring. The brown
solid (R2Sn)2MCln[meso-tetra(4-sulfonatophenyl)porphi-
nate]s, which precipitated on cooling, were recovered,
recrystallized from methanol and dried over P4O10.
R2SnO (R = Me, n-Bu, Ph), (n-Bu3Sn)2O and Ph3SnOH
used in the syntheses, were freshly prepared by hydrolysis
of the parent organotin(IV)chloride (Fluka, Bucks, Swit-
zerland) and recrystallized from benzene, while Me3SnOH
was a Alfa Aesar product (Johnson Matthey GmbH,
Karlsruhe, Germany). The free Fe(III)ClH4[meso-tetra-
(4-sulfonatophenyl)porphinate], Mn(III)ClH4[meso-tetra-
(4-sulfonatophenyl)porphinate] and Sn(IV)Cl2H4[meso-
tetra(4-sulfonatophenyl)porphinate] ligands (Fig. 1a and
b) were Porphyrin Products (Logan, UT, USA).
2.1.2. (R3Sn)4MCln[meso-tetra(4-sulfonatophenyl)-
porphinate]s, [M = Fe(III), Mn(III): n = 1, R = Me,
n-Bu; Ph; M = Sn(IV): n = 2, R = Me]
MClnH4[meso-tetra(4-sulfonatophenyl)porphine] were
allowed to react into 50 ml of CH3OH, for 24 h at about
40 °C, under a constant stirring, together with the stoichio-
metric amount of Me3SnOH, (Bu3Sn)2O or Ph3SnOH.
The brown solid (R3Sn)4MCln[meso-tetra(4-sulfonatophe-
(R2Sn)2MCln[meso-tetra(4-sulfonatophenyl)porphinate]s
and
(R3Sn)4MCln[meso-tetra(4-sulfonatophenyl)porphi-
nate]s, (M = Fe(III), Mn(III): n = 1, R = Me, n-Bu; Ph;
M = Sn(IV): n = 2, R = Me, n-Bu), have been obtained
according to the following procedures.

C. Pellerito et al. / Journal of Organometallic Chemistry 691 (2006) 1573–1583
1575
nyl)porphinate]s obtained were recovered by filtration,
recrystallized from methanol and dried over P4O10 under
vacuum.
The recrystallized solids were analyzed for C, H, N,
S contents (Table 1), by using a Vario EL III CHNS
elemental analyzer (Elementar Analysensysteme GmbH,
Hanau, Germany).
Thermogravimetric (TG) measurements were carried out
from room temperature (=RT) up to 600 °C, with a Mettler
TA-300 system operating in a pure nitrogen atmosphere, in
alumina crucible and at a heating rate of 5 °C/min, using
alumina as reference. The organotin(IV)MCln- [meso-
tetra(4-sulfonatophenyl)porphinate] complexes had a char-
acteristic thermal decomposition pattern, between 60 and
110 °C, due to loss of six water molecules (Table 1). The
experimental results and in particular the temperature at
which the water molecules have been lost, should exclude
any involvement in coordination sphere of the tin atom.
FT-IR spectra (Table 2) were registered, as nujol and
hexachlorobutadiene mulls, on a Mod. Spectrum one Per-
kin–Elmer FT-IR, between CsI windows, in the 4000–
250 cmꢀ1 region.
maintained at liquid nitrogen temperature in a model
NDR-1258-MD Cryo liquid nitrogen cryostat (Cryo
Industries of America, Inc., Atkinson, NH, USA) with a
Cryo sample holder. The 77.3 0.1 K temperature was
controlled with a model ITC 502 temperature controller
of the Oxford Instruments (Oxford, England). The multi-
channel calibration was performed with an enriched iron
foil [57Fe = 95.2%, thickness 0.06 mm, Dupont, MA
(USA)], at room temperature, by using a 57Co–Pd source
[(10 mCi, Ritverc GmbH, St. Petersburg (Russia)], while
the zero point of the Doppler velocity scale has been deter-
mined, at room temperature, through absorption spectra of
natural CaSnO3 (
119Sn = 0.5 mg/cm2) and a Ca119SnO3
source [10 mCi, Ritverc GmbH, St. Petersburg (Russia)].
The obtained 5 Æ 105 count spectra were refined, to obtain
the isomer shift, d (mm sꢀ1), and the nuclear quadrupole
splitting, |Dexp| (mm sꢀ1), values reported in Table 3.
2.2. Quantum chemical calculations
Two layers ONIOM calculations [11], with full geometry
optimization, were performed on the structure of
(Me3Sn)4Sn(IV)Cl2TPPS, as well as of Sn(IV)Cl2H4TPPS
and (Me3Sn)4H2TPPS, for comparison purposes, and on
the two model complexes of trimethyltin(IV) and dimethyl-
tin(IV) with the ligand phenylsulfonic acid (HPS),
Me3Sn(PS)(HPS) and Me2Sn(PS)2. The density functional
theory (DFT) hybrid Becke’s three-parameter method
(B3LYP) level, with the double-zeta valence plus polariza-
tion (DZVP) basis set [12], was used for the higher layer,
including the tin-dichloride protoporphyrin environment
or the di- or trimethyltin(IV)-sulfonate environment,
respectively; the semiempirical AM1 method was used for
the lower layer. All calculations were performed by the
GAUSSIAN-98 program package [13]. The 119Sn Mo¨ssbauer
nuclear quadrupole splitting was calculated by the calibra-
tion formula Dcalcd = 0.93 Æ V 0.58 mm sꢀ1 [12], where
1H and 13C NMR spectra of non-paramagnetic organo-
tin(IV) derivatives were recorded on a Bruker AC 250E
instrument, operating at 63 and 250 MHz, respectively,
using DMSO as solvent and tetramethylsilane (TMS) as
internal reference; using D2O as solvent, DSS [=3-(tri-
methylsilyl)-1-propanesulfonic acid sodium salt] has been
used as external reference (Tables 6 and 7).
The 119Sn Mo¨ssbauer spectra (Table 3) were measured
at liquid nitrogen temperature with a multichannel ana-
lyzer [TAKES Mod. 269, Ponteranica, Bergamo (Italy)]
and the following Wissenschaftliche Elektronik system
[MWE, Munchen (Germany)]: an MR250 driving unit,
¨
an FG2 digital function generator and an MA250 velocity
transducer, moved at linear velocity, constant acceleration,
in a triangular waveform. The organotin(IV) samples were
Table 1
Analytical data [calculated % values in parentheses] of (R2Sn)2MCln[meso-tetra(4-sulfonatophenyl)porphinate] and (R3Sn)4MCln[meso-tetra(4-sulfona-
tophenyl)porphinate] (M = Fe(III), Mn(III): n = 1, R = Me, n-Bu; Ph; M = Sn(IV): n = 2, R = Me, n-Bu)
Compounda
C
H
N
S
H2O
(Me2Sn)2FeClTPPS Æ 6H2O
(n-Bu2Sn)2FeClTPPS Æ 6H2O
(Ph2Sn)2FeClTPPS Æ 6H2O
(Me3Sn)4FeClTPPS Æ 6H2O
(n-Bu3Sn)4FeClTPPS Æ 6H2O
(Ph3Sn)4FeClTPPS Æ 6H2O
(Me2Sn)2MnClTPPS Æ 6H2O
(n-Bu2Sn)2MnClTPPS Æ 6H2O
(Ph2Sn)2MnClTPPS Æ 6H2O
(Me3Sn)4MnClTPPS Æ 6H2O
(n-Bu3Sn)4MnClTPPS Æ 6H2O
(Ph3Sn)4MnClTPPS Æ 6H2O
(Me2Sn)2SnCl2TPPS Æ 6H2O
(n-Bu2Sn)2SnCl2TPPS Æ 6H2O
(Me3Sn)4SnCl2TPPS Æ 6H2O
a
40.73 (40.43)
45.02 (45.20)
48.30 (48.79)
37.55 (37.71)
49.83 (48.28)
57.26 (55.10)
39.87 (40.46)
44.76 (45.23)
48.99 (48.81)
38.33 (37.73)
49.23 (48.30)
54.38 (55.12)
37.19 (37.82)
43.15 (42.58)
34.92 (35.74)
3.14 (3.39)
4.96 (4.55)
3.64 (3.37)
4.24 (4.07)
6.60 (6.34)
3.34 (3.83)
3.96 (3.40)
4.57 (4.55)
3.77 (3.37)
4.34 (4.07)
5.51 (6.34)
3.97 (3.82)
3.29 (3.17)
4.30 (4.28)
3.56 (3.85)
3.35 (3.93)
3.50 (3.51)
3.17 (3.35)
3.25 (3.14)
2.49 (2.45)
2.51 (2.22)
4.10 (3.93)
3.71 (3.52)
3.23 (3.35)
3.53 (3.14)
3.71 (2.45)
2.41 (2.22)
3.57 (3.67)
3.26 (3.31)
2.77 (2.97)
8.46 (9.00)
7.56 (8.05)
7.08 (7.66)
7.11 (7.19)
5.79 (5.61)
5.39 (5.07)
8.43 (9.00)
7.88 (8.05)
7.72 (7.67)
7.32 (7.20)
7.65 (5.61)
4.76 (5.08)
8.80 (8.41)
7.90 (7.58)
6.61 (6.81)
7.82 (7.56)
7.31 (6.97)
7.05 (6.45)
7.00 (6.06)
4.63 (4.72)
5.01 (4.27)
7.28 (7.58)
6.78 (6.11)
6.85 (6.45)
6.06 (6.54)
4.43 (4.72)
5.50 (4.27)
6.98 (7.09)
6.41 (6.63)
6.02 (5.74)
FeClTPPS4ꢀ = Fe(III)Cl[meso-tetra(4-sulfonatophenyl)porphinate]4ꢀ; MnClTPPS4ꢀ = Mn(III)Cl[meso-tetra(4-sulfonatophenyl)porphinate]4ꢀ; SnCl2-
TPPS4ꢀ = Sn(IV)Cl2[meso-tetra(4-sulfonatephenyl)porphinate]4ꢀ
.

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C. Pellerito et al. / Journal of Organometallic Chemistry 691 (2006) 1573–1583
Table 2
Relevant absorption bands of Me3SnSO3Ra (R = CH3,CF3), H4MCln[meso-tetra(4-sulfonatophenyl)porphinate], (R2Sn)2MCln[meso-tetra(4-sulfonatoph-
enyl)porphinate] and (R3Sn)4MCln[meso-tetra(4-sulfonatophenyl)porphinate] derivatives [(M = Fe(III), Mn(III); n = 1; R = Me, n-Bu, Ph), (M = Sn(IV),
n = 2, R = Me, n-Bu)] in the 4000–250 cmꢀ1 regionb
Compoundsc/assignment
m(SO3) (A00) m(SO3) (A0) m(SO3) (A0) m(SO3) (A00) m(SO3) (A0) m(SO3) (A0) q(SO3) (A00) q(SO3) (A0) Y-mode
Me3SnSO3CH3
1266s
1112vs
1035s
562s
531s
516ms
352m,sh
346m,sh
356ms
347s
275m,sh
Me3SnSO3CF3
1319vs
1145s
1026s
633s
577ms
530m,sh
317m
H4FeClTPPS
(Me2Sn)2FeClTPPS Æ 6H2O
1203s
1202s
1123s
1121s
1034vs
1035vs
577s
579s
n.o.
549w
n.o.
520w
371w
342w
370w
341w
368w
341w
363w
337w
364w
337w
370m
341w
285w
281w
284w
279w
283w
280w
(n-Bu2Sn)2FeClTPPS Æ 6H2O 1203s
1119s
1121s
1121s
1118s
1112s
1033vs
1034vs
1036vs
1035vs
1034vs
580s
548w
551w
553m
551w
549m
522w
525w
521w
521w
520w
(Ph2Sn)2FeClTPPS Æ 6H2O
(Me3Sn)4FeClTPPS Æ 6H2O
1203s
579s
450m
453m
1202m
580w
579m
579w
(n-Bu3Sn)4FeClTPPS Æ 6H2O 1203m
(Ph3Sn)4FeClTPPS Æ 6H2O
1202m
H4MnClTPPS
1206
1123
1035
578
551
526
(Me2Sn)2MnClTPPS Æ 6H2O
1205m
1121s
1035vs
580s
548w
523w
355w
335w
346w
330w
350w
330s
350w
335w
349w
330w
350w
330s
275m
272m
270m
276w
270w
273m
(n-Bu2Sn)2MnClTPPS Æ 6H2O 1206m
1119s
1122s
1124s
1119s
1118s
1034vs
1035vs
1036vs
1035vs
1035vs
579s
579s
579s
580s
580s
550w
550m
551m
550w
550w
525w
522w
523w
520w
526w
(Ph2Sn)2MnClTPPS Æ 6H2O
(Me3Sn)4MnClTPPS Æ 6H2O
1206m
1205m
451m
453m
(n-Bu3Sn)4MnClTPPS Æ 6H2O 1206s
(Ph3Sn)4MnClTPPS Æ 6H2O
1205m
H4SnCl2TTPS
(Me2Sn)2SnCl2TPPS Æ 6H2O
1215m,bd
1214s
1124m
1123s
1033s
1036s
577m
579s
548w
550w
n.o
520w
390w
380w
385w
375w
385w
375vw
280w
290w
290vw
(n-Bu2Sn)2SnCl2TPPS Æ 6H2O 1212s
1123s
1124s
1035s
1036s
580m
581m
550w
550s
520w
530w
(Me3Sn)4SnCl2TPPS Æ 6H2O
1210s
a
See Ref. [14].
b
s = Strong, m = medium, w = weak, sh = shoulder, bd = broad, v = very, n.o. = not observed.
c
FeClTPPS4ꢀ = Fe(III)Cl[meso-tetra(4-sulfonatophenyl)porphinate]4ꢀ; MnClTPPS4ꢀ = Mn(III)Cl[meso-tetra(4-sulfonatophenyl)porphinate]4ꢀ, SnCl2-
TPPS4ꢀ = Sn(IV)Cl2[meso-tetra(4-sulfonatophenyl)porphinate]4ꢀ
.
"
#
tion of the sulfonate group RSOꢀ3 should decrease the sym-
metry to Cs, removing in this way the degeneracy of the E
mode vibrations. As a consequence, the coordinated sulfo-
nate group should originate six A0 and three A00 vibrational
modes. The infrared data of all the newly synthesized com-
plexes, (R2Sn)2MCln[meso-tetra(4-sulfonatophenyl)porphi-
nate]s and (R3Sn)4MCln[meso-tetra(4-sulfonatophenyl)-
porphinate]s showed the occurrence of the nine expected
S–O vibrations, Table 2, which, according to previous
reports [6,14–19], may be attributed to a monoanionic
mono or bidentate binding of the sulfonate groups. These
findings would support a six coordination around the
tin(IV) atom in the (R2Sn)2MCln[meso-tetra(4-sulfona-
tophenyl) porphinate] complexes, with trans-R2 octahedral
configuration, possibly in a polymeric configuration. Four
or five coordination, the latter with a monomeric bidentate
1=2
ꢀ
ꢁ
2
1
3
V xx ꢀ V yy
V ¼ V zz 1 þ
;
V zz
and where Vxx, Vyy, Vzz, following the condition
|Vzz| P |Vyy| P |Vxx|, are the eigenvalues of the diagonal-
ized electric field gradient tensor, calculated at the same le-
vel of theory of the higher layer.
3. Results and discussion
3.1. IR spectra
According to the literature reports, the ionic sulfonate
group RSOꢀ, C3v symmetry, should present in its IR spec-
3
trum six fundamental vibrations, three of which should be
A0 and three doubly degenerate E modes [14]. Coordina-

C. Pellerito et al. / Journal of Organometallic Chemistry 691 (2006) 1573–1583
1577
Table 3
Experimental Mo¨ssbauer parameters, isomer shift, d, mm sꢀ1, and nuclear quadrupole splittings, |Dexp|, mm sꢀ1, of H4Fe(III)Cl[meso-tetra(4-
sulfonatophenyl)porphine], H4Sn(IV)Cl2[meso-tetra(4-sulfonatophenyl)porphine], (R2Sn)2MCln[meso-tetra(4-sulfonatphenyl)porphinate], (R3Sn)4 MCln-
[meso-tetra(4-sulfonatophenyl)porphinate], [(M = Fe(III), Mn(III), n = 1, R = Me, n-Bu, Ph); (M = Sn(IV), n = 2, R = Me, n-Bu)], measured at liquid N2
temperature
Compoundsa
dSn (mm sꢀ1
)
|Dexp
|
(mm sꢀ1
)
dFe (mm sꢀ1
)
|Dexp|c (mm sꢀ1
)
b
b
c
H4Fe(III)ClTPPS
0.23
0.24
0.22
0.25
0.23
0.23
0.20
0.34
0.32
0.36
0.36
0.32
0.36
0.33
(Me2Sn)2FeClTPPS Æ 6H2O
(n-Bu2Sn)2FeClTPPS Æ 6H2O
(Ph2Sn)2FeClTPPS Æ 6H2O
(Me3Sn)4FeClTPPS Æ 6H2O
(n-Bu3Sn)4FeClTPPS Æ 6H2O
(Ph3Sn)4FeClTPPS Æ 6H2O
1.36
1.52
1.20
1.41
1.52
1.30
4.29
4.74
3.70
3.94
4.08
3.52
dSn (mm sꢀ1
)
|Dexp
|
(mm sꢀ1
)
dSn (mm sꢀ1
)
|Dexp
|
(mm sꢀ1
)
b
b
b
b
(Me2Sn)2MnClTPPS Æ 6H2O
(n-Bu2Sn)2MnClTPPS Æ 6H2O
(Ph2Sn)2MnClTPPS Æ 6H2O
(Me3Sn)4MnClTPPS Æ 6H2O
(n-Bu3Sn)4MnClTPPS Æ 6H2O
(Ph3Sn)4MnClTPPS Æ 6H2O
H4SnCl2TPPS
1.46
1.54
1.37
1.32
1.56
1.33
4.29
4.64
3.70
3.39
4.23
3.39
0.27
0.27
0.27
0.27
1.04
1.07
1.04
1.04
(Me2Sn)2SnCl2TPPS Æ 6H2O
(Bu2Sn)2SnCl2TPPS Æ 6H2O
(Me3Sn)4SnCl2TPPS Æ 6H2O
a
1.36
1.54
1.45
4.06
4.16
3.53
FeClTPPS4ꢀ = Fe(III)Cl[meso-tetra(4-sulfonatophenyl)porphinate]4ꢀ
; ; SnCl2-
MnClTPPS4ꢀ = Mn(III)Cl[meso-tetra(4-sulfonatophenyl)porphinate]4ꢀ
TPPS4ꢀ = Sn(IV)Cl2[meso-tetra (4-sulfonatophenyl)porphinate]4ꢀ; sample thickness ranged between 0.50 and 0.60 mg 119Sn cmꢀ2
.
b
Isomer shift, d 0.03 mm sꢀ1 with respect to RT BaSnO3; nuclear quadrupole splittings, |D| 0.02 mm sꢀ1
.
c
Isomer shift, d 0.03 mm sꢀ1 with respect to RT enriched 57Fe foil (57Fe = 95.2%); nuclear quadrupole splittings, |D| 0.02 mm sꢀ1
.
or a polymeric monodentate trigonal bipyramidal environ-
ment around the tin(IV) atom, may be invoked for the
(R3Sn)4MCln[meso-tetra(4-sulfonatophenyl)porphinate]
complexes.
Furthermore, the Sn–Ph Y-mode of Whiffen [20] was
present at around 450 cmꢀ1 for (Ph2Sn)2MCln[meso-tetra-
(4-sulfonatophenyl)porphinate]s and (Ph3Sn)4MCln-[meso-
tetra(4-sulfonatophenyl)porphinate]s. As far as m(SnCl)
stretching frequency related to the central SnCl2 moieties
in organotin-SnCl2[meso-tetra(4-sulfonatophenyl)porphi-
nate]s (ranging from 300 to 310 cmꢀ1), the frequency is
comparable with the reported value of 309 cmꢀ1 for
SnCl2[tetra-p-tolylporphyrin] [21].
[meso-tetra(4-sulfonatophenyl)porphinate]s and (R3Sn)4-
Fe(III)Cl[meso-tetra(4-sulfonatophenyl)porphinate]s, are
characteristic of Fe(III) S = 5/2 compounds [22]. The
invariance of d, on going from the free Fe(III)ClH4[meso-
tetra(4-sulfonatophenyl)porphine] to the complexes, shows
that the 57Fe Mo¨ssbauer parameter d is independent from
the withdrawing or releasing electronic effects of the organo-
tin(IV) moieties coordinated to the side chain sulfonate
groups. On the other hand, according to previous reports
[23], both (R2Sn)2Fe(III)Cl[meso-tetra(4-sulfonatophe-
nyl)porphinate] and (R3Sn)4Fe(III)Cl[meso-tetra(4-sulfon-
atophenyl)porphinate] complexes which possess, compared
to the free Fe(III)ClH4[meso-tetra(4-sulfonatophenyl)por-
phine], methyl and butyl electron-releasing substituents,
should have larger D values. Table 3 also shows that, for
the investigated complexes, the 57Fe |Dexp| values vary, with
respect to the free Fe(III)ClH4[meso-tetra(4-sulfonatophe-
nyl)porphine], within the experimental errors.
An asymmetric distribution of the electron charges
around the 57Fe, gives a non-zero electric field gradient.
According to the |Dexp| values obtained (Table 3), it is pos-
sible to hypothesize that the side chain organotin(IV) moie-
ties do not influence neither the lattice contribution, qlat,
arising from the four endocyclic nitrogen atoms of the por-
phyrin ring and from the chloride directly bonded to the
iron(III) center, nor the valence contributions, qval, resulting
from the asymmetric distribution of electrons in the bonding
and non-bonding orbitals and in particular from the effective
population of the 3d and 4p orbitals of the Fe(III) [24].
As far as 119Sn Mo¨ssbauer data are concerned, the
trend of the isomer shift values of the complexes, d,
3.2. 57Fe and 119Sn Mo¨ssbauer spectra
Both 57Fe and 119Sn Mo¨ssbauer spectroscopies have been
applied to (R2Sn)2Fe(III)Cl[meso-tetra(4-sulfonatophenyl)-
porphinate]s and to (R3Sn)4Fe(III)Cl[meso-tetra(4-sulfo-
natophenyl)porphinate]s (Table 3, Fig. 2a and b), while only
119Sn Mo¨ssbauer spectroscopy has been used to investigate
(R2Sn)2Mn(III)Cl[meso-tetra(4-sulfonatophenyl)porph-
inate]s, (R3Sn)4Mn(III)Cl[meso-tetra(4-sulfonatophenyl)-
porphinate]s, (R2Sn)2Sn(IV)Cl2[meso-tetra(4-sulfonatophe-
nyl)-porphinate]s and, finally, (R3Sn)4Sn(IV)-Cl2[meso-
tetra(4-sulfonatophenyl)porphinate]s (Table 3).
The isomer shifts, d (mm sꢀ1) and the experimental
nuclear quadrupole splittings, |Dexp| (mm sꢀ1), measured
with 57Fe Mo¨ssbauer spectroscopy, both for the free
Fe(III)ClH4[meso-tetra(4-sulfonatophenyl)porphine], and
for all its organotin(IV) derivatives, (R2Sn)2Fe(III)Cl-

1578
C. Pellerito et al. / Journal of Organometallic Chemistry 691 (2006) 1573–1583
1.005
1
present in the organotin(IV)MCln[meso-tetra(4-sulfona-
tophenyl)porphinate]s, results in smaller nuclear quadru-
pole splittings, see Table 3.
A typical Mo¨ssbauer spectrum for (Me3Sn)4Sn(IV)-
Cl2TPPS is reported in Fig. 3 in which the contribution
of the inorganic tin(IV) (|Dexp| = 1.04 mm sꢀ1) and of the
triorganotin(IV) moieties (|Dexp| = 3.53 mm sꢀ1) are visible,
characteristic of eq-R3 trigonal bipyramidal geometry,
Fig. 4c).
In conclusion, according both to IR and Mo¨ssbauer
findings, polymeric octahedral trans-R2Sn configurations
are proposed, for diorganotin(IV)M(III)Cl[meso-tetra(4-
sulfonatophenyl)porphinate]s (Fig. 4a and b), and
polymeric trigonal bipyramidal equatorial R3Sn for triorg-
anotin(IV)-M(III)Cl[meso-tetra(4-sulfonatophenyl)porphi-
nate]s (Fig. 4c).
0.995
0.99
0.985
0.98
0.975
-6
-4
-2
0
2
4
6
In the structures shown in Fig. 4a and b, the formal
charge 2+ of each of two diorganotin(IV) moieties is coun-
terbalanced by the total 4ꢀ charge of four bridging or of
two chelating monoanionic sulfonate groups. In both cases,
the coordination polyhedron of tin(IV) should be formed by
four equatorial oxygen atoms and two trans-R2 groups. In
the latter case, equal bonding situation should be envisaged
for each of the four sulfonate groups of the porphine ligand,
thus giving origin to a complex polymeric structure, where
all the diorganotin(IV) groups should be inter-connected
by two bridging sulfonate groups, belonging to two different
[meso-tetra(4-sulfonatophenyl) porphinate] molecules.
A similar structure should be hypothesized also for the
triorganotin(IV) complexes, where, however, there should
be only one sulfonate bridge between each pair of metal
atoms, and two of such bridges for each triorganotin(IV)
moiety, counterbalancing the formal +1 charge on the
tin(IV) atom. The coordination polyhedron of the tin(IV)
atom should be a trigonal bipyramid with equatorial
SnC3 units and two axial oxygen atoms, from two sulfo-
nate groups belonging to two different ligand molecules.
Velocity, mm/s
a
1.005
1
0.995
0.99
0.985
0.98
-6
-4
-2
0
2
4
6
Velocity, mm/s
b
Fig. 2. (a) 57Fe Mo¨ssbauer spectrum of (n-Bu3Sn)4FeClTPPS Æ 6H2O.
(b) 119Sn Mo¨ssbauer spectrum of (n-Bu3Sn)4FeClTPPS Æ 6H2O.
reflected the meaning of the parameter, increasing from
methyl to butyltin(IV)MCln[meso-tetra(4-sulfonatophenyl)-
porphinate] derivatives and decreasing in phenyltin-
(IV)MCln[meso-tetra(4-sulfonatophenyl)porphinate], M =
Fe(III), Mn(III). This trend, according to the literature
reports [25–27], reflects the difference in number and elec-
tronegativity of the organic radicals bonded to the tin(IV)
atom. In Table 3 are reported, for comparison purpose,
the isomer shifts of several tin and organotin sulfonate
complexes, previously reported in the literature [14–18],
from which it is possible to evidence the covalent character
[14] of the bonds in the complexes reported in this paper.
The electronegativity of the SO3 groups in MCln-
[meso-tetra(4-sulfonatophenyl)porphinate]4ꢀ, M = Fe(III),
Mn(III), Sn(IV) according to Yeats et al. [16], causes a
withdrawal of p-electron density of the tin in organotin(IV)
moieties, with concomitant deshielding of the tin 5s elec-
trons, resulting in the d values observed. Additionally,
the above mentioned imbalance in the p orbital charge
1.005
1
0.995
0.99
0.985
0.98
0.975
0.97
0.965
0.96
-8
-6
-4
-2
0
2
4
6
8
Velocity, mm/s
Fig. 3. 119Sn Mo¨ssbauer spectrum of (Me3Sn)4SnCl2TPPS Æ 6H2O.

C. Pellerito et al. / Journal of Organometallic Chemistry 691 (2006) 1573–1583
1579
[meso-tetra(4-sulfonatophenyl)porphinate]. Moreover, this
model allows us to get detailed information of the structure
of the SnCl2 moiety coordinated by the porphyrin nitrogen
atoms. The results obtained show that the SnCl2 group,
within the porphyrin plane, lies in a regular octahedral
structure, analogously to what observed in Sn(IV)Cl2H4-
[meso-tetra(4-sulfonatophenyl)porphinate].
R
O
R'
O
O
O
S
S
Sn
R'
O
O
R
a
O
R'
O
R'
Concerning the peripheral Me3Sn(IV) groups, the calcu-
lated parameters for the considered system (Table 4) allow
us to conclude that their structure could be described as a
tetrahedral environment, with a strong Sn2–O1 and an
additional weak Sn2–O2 bond, distorted towards a trigonal
bipyramidal configuration in analogy to what observed for
(Me3Sn)4H2[meso-tetra(4-sulfonatophenyl)porphinate].
To mimic the possible polymeric coordination of the
Me3Sn(IV) moieties by the sulfonate groups of two different
[meso-tetra(4-sulfonatophenyl)porphinate] derivative ligands,
the structure shown in Fig. 5b was considered as model sys-
tem. It turns out that the sulfonate groups would act, in this
case, as monodentate axial ligands with the methyl groups
in the equatorial plane of a distorted tbp structure (see
Table 4). For both the monomer and polymer model sys-
tems, reported in Fig. 5a–c there is a good agreement
between the calculated nuclear quadrupole splitting value
and the corresponding experimental value obtained for
(Me3Sn)4SnCl2[meso-tetra(4-sulfonatophenyl)porphinate]
(Table 5). However, the occurrence of Mo¨ssbauer effect at
room temperature for (Me3Sn)4SnCl2[meso-tetra(4-sulfona-
tophenyl)porphinate] would induce us to preferably attri-
bute the polymeric structure reported in Fig. 5b for the
triorganotin(IV) complexes of the [meso-tetra(4-sulfona-
tophenyl)porphinate] derivatives investigated.
S
S
S
S
R
R
Sn
R
R
O
O
O
O
O
O
O
O
O
O
O
Sn
R
Sn
R
O
R'
O
R'
O
b
O
R'
O
O
R'
O
R'
R
R
S
S
S
O
O
Sn
R
O
Sn
O
O
R
R
R
c
Fig. 4. Proposed octahedral polymeric configurations for (R2Sn)2-
MCln[meso-tetra(4-sulfonatophenyl)porphinate], (a and b), through che-
lating (a) or bridging (b) sulfonate groups coordinating in the equatorial
plane, and trigonal bipyramidal polymeric configuration for
(R3Sn)4MCln[meso-tetra(4-sulfonatophenyl)porphinate] (c), [M = Fe(III),
Mn(III), n = 1, R = Me, n-Bu, Ph; M = Sn(IV), n = 2, R = Me, n-Bu;
R0 = meso-tris(3-sulfonatophenyl)porphinate].
3.3. Quantum chemical calculations
We mention that any attempt to optimize the dimethyl-
tin(IV)-phenylsulfonate coordination geometry in the envi-
ronment proposed in Fig. 4b failed, essentially as a
consequence of a strong steric repulsion between the vicinal
R0 groups.
On the other hand, the system considered in Fig. 5c
mimics a polymeric trans-Me2 octahedral coordination of
the tin atom in the (Me2Sn)2SnCl2[meso-tetra(4-sulfona-
tophenyl)porphinate] complex. The structural parameters
obtained (Table 4) show that this structure can be
described as a distorted trans-Me2 octahedron, with a quite
small C–Sn–C bond angle, and with an asymmetric chela-
tion of the sulfonate groups to the tin atom. The very good
agreement between the experimental and the calculated
119Sn D values (Table 5) allow us to suggest the proposed
structural attribution for the organotin(IV) complexes of
the investigated derivatives.
The experimental 119Sn |D| values obtained for the triorg-
anotin(IV) moieties coordinated by the [meso-tetra(4-sulf-
onatophenyl)porphinate] derivative ligands (Table 3) are
typical of tbp structures [28]. This leads to two possible
structural hypotheses for the tin environment of these
peripheral organotin groups: (i) a monomeric monodentate
coordination or (ii) a polymeric bidentate coordination of
the phenylsulfonate groups (see Fig. 4c). On the other hand,
the 119Sn |Dexp| values observed for the diorganotin(IV) moi-
eties in analogous systems (Table 3) are typical of trans-R2
octahedral coordination [28] and, considering the stoichi-
ometry of such systems, could be well contemplated by a
polymeric chelating bidentate or bridging coordination of
the phenylsulfonate groups (see Fig. 4a and b).
To rationalize these structural hypotheses on the tin coor-
dination environment, inferred on the basis of the spectro-
scopic evidences obtained for the investigated compounds,
quantum chemical calculations have been performed on
the model systems shown in Fig. 5a–c. The relevant struc-
tural data of the optimized geometries are reported in Table
4, while the corresponding calculated 119Sn D values are
reported in Table 5.
1
3.4. H and 13C NMR spectra of diorganotin(IV) and
triorganotin(IV)[meso-tetra(4-sulfonatophenyl)-
porphinatetin(IV)dichloride] complexes
1H and 13C NMR spectra of aqueous (D2O) solutions of
non-paramagnetic complexes have been investigated. Cau-
tion must be exercised in interpreting NMR spectra of
The first system considered (Fig. 5a) mimics a mono-
meric tbp coordination of the complex (Me3Sn)4SnCl2-

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C. Pellerito et al. / Journal of Organometallic Chemistry 691 (2006) 1573–1583
N1
Cl
Sn1
N2
C2
C1
N3
Cl
Sn2
O1
O2
C3
a
O4
C2
C3
O3
O1
O2
Sn2
C1
b
C2
O3
O1
Sn2
O4
O2
C1
c
Fig. 5. Optimized structures (see text) of the monomeric (Me3Sn)4SnCl2TPPS complex (a), and of Me3Sn(PS)(HPS) (b) and Me2Sn(PS)2 (c), the latter two
being models of the polymeric complexes of di- and trimethyltin(IV)-TPPS.
meso-tetra(4-sulfonatophenyl)porphine (H6TPPS), metal-
loporphine derivative SnCl2H4TPPS and its organometallic
complexes reported in this work, since they appear to be
dependent on experimental conditions such as concentra-
tion, temperature and solvent; moreover the use of DSS
[3-(trimethylsilyl)-1-propanesulfonic acid sodium salt], as

C. Pellerito et al. / Journal of Organometallic Chemistry 691 (2006) 1573–1583
1581
Table 4
NMR, compared with Sn(IV)Cl2TPP, where no high-field
peak due to Sn(OH)2 is observed [29]. For both complexes,
satellites are observed flanking the b-pyrrole proton reso-
nance, which are assigned to long-range coupling to the
tin(IV) nucleus over four bonds. The X-ray structure of
meso-tetraphenylporphyrinatotin(IV) complexes with chlo-
ride, water, hydroxide, benzoate, salicylate and acetylsalyc-
ilate as axial ligands has been reported [30,31] all
complexes being monomeric with little structural variations
within the TPP framework. Cis-influences in octahedral
tin(IV)X2 meso-tetraphenylporphyrin complexes have been
evaluated and correlations between spectroscopic proper-
ties and the nature of axial ligands X have been discussed.
The tin(IV)-proton coupling constants to the b-pyrrole
protons decrease from 19.2 Hz (X = ClO4) to 10.4 Hz
(9.5 Hz according to Ref. [28]) (X = OH) while for
X = Cl 4J(Sn,H) = 15.2 Hz (15.5 according to Ref. [28])
[32–34]. Coupling constants for the oxygen bounds ligands
correlate satisfactory with the basicity of the ligands, while
the halides do not fit this relationship possibly due to the
overall effect of p back-bonding from chlorine to tin, effec-
tively ‘‘tightening’’ coordination to the tin(IV) nucleus as
suggested by the authors (see Table 6).
The chemical shifts of the b-protons also depend on the
nature of X and a similar dependence on ligand basicity is
observed,with weaker bases causing downfield shifts (d for
OH < d for Cl < d for ClO4).
A detailed study of the effect of axially bound anions on
the electrochemistry and spectroelectrochemistry, including
1H NMR, of tin(IV)X2 meso-tetra-p-tolylporphyrin or
meso-tetra-m-tolylporphyrin has been reported [21]. An
agreement with previously reported pattern is found, since
the Sn(IV)Cl2 derivative has a larger coupling constant
than its bromide, hydroxo and fluoride analogues.
˚
Relevant geometrical parameters (bond distances/A and angles/°) relative
to the tin environment in the higher layer of the systems shown in Fig. 5a–
c, calculated at DFT level by the ONIOM method (see text)
(Me3Sn)4SnCl2TPPS
Me3Sn(PS)(HPS)
Me2Sn(PS)2
Sn1–Cl
Sn1–N
2.47
2.13
–
–
–
–
Cl–Sn1–Cl
N1–Sn1–N2
N1–Sn1–N3
Cl–Sn1–N
180
90
180
90
–
–
–
–
–
–
–
–
Sn2–C
2.16
2.12
3.19
–
2.17
2.15
3.29
2.96
4.65
2.15
2.14
2.72
2.14
2.72
Sn2–O1
Sn2–O2
Sn2–O3
Sn2–O4
–
O1–Sn2–O2
O1–Sn2–O3
O1–Sn2–O4
C1–Sn2–C2
C1–Sn2–C3
C2–Sn2–C3
O1–Sn2–C1
O1–Sn2–C2
O1–Sn2–C3
O2–Sn2–C1
O2–Sn2–C2
O2–Sn2–C3
51
–
–
115
117
115
105
96
105
78
147
81
49
173
146
117
118
117
101
94
58
84
142
135
–
–
106
107
–
86
87
–
102
80
80
83
HPS = phenylsulfonic
sulfonatophenyl)porphinate]4ꢀ
Sn1 is the tin atom of the SnCl2TPPS4ꢀ anion; Sn2 is the tin atom of the
organotin moiety (Fig. 5a–c).
acid;
SnCl2TPPS4ꢀ = Sn(IV)Cl2[meso-tetra(4-
;
Table 5
119Sn Mo¨ssbauer nuclear quadrupole splitting (D, mm sꢀ1), relative to the
indicated tin atom, calculated (see text) for the compounds shown in
Fig. 5a–c, and compared to the corresponding experimental values
obtained for (Me2Sn)2SnCl2TPPS Æ 6H2O and (Me3Sn)4SnCl2TPPS Æ
6H2O (see Table 3)
The kinetics of consecutive second-order two-steps
hydrolysis of dimethoxo(meso-tetra-p-tolylporphyrinato)-
tin(IV) has also been studied in CDCl3 [35].
Compounda
Tin atomb
|Dexp
|
Dcalcd
(Me3Sn)4SnCl2TPPS Æ 6H2O
(Me3Sn)4SnCl2TPPS Æ 6H2O
Me3Sn(PS)(HPS)
Me2Sn(PS)2
Sn(1)
Sn(2)
Sn(2)
Sn(2)
1.04
3.53
3.53
4.06
0.82
ꢀ3.49
ꢀ3.76
3.94
We previously investigated the interaction of [meso-
tetra(4-sulfonatophenyl)porphine with diorgano and
triorgano(IV) moieties and configurations of the complexes
1
in DMSO-d6 have been reported [6], hence the H and 13C
a
SnCl2TPPS4ꢀ =Sn(IV)Cl2[meso-tetra(4-sulfonatophenyl)porphinate]4ꢀ
;
HPS = phenylsulfonic acid.
NMR spectra of the new complexes may offer evidence of
the influence of both peripheral organotin(IV) and central
Sn(IV) substitution. 10ꢀ3 M solutions in D2O of the
dimethyl- and trimethyltin(IV) complexes have been
obtained, while nearly saturated solutions of (n-Butyl)2-
Sn(IV) derivative has been examined, giving broad poorly
resolved NMR spectra for the latter. For the former com-
plexes conductivity measurements, which agree with a 1:2
electrolyte, indicate the formation of diaqua species.
4J(Sn,H) coupling constants involving 119Sn and 117Sn
nuclei (natural abundances 8.6% and 7.6%, respectively)
and b-pyrrole protons are reported in Table 1. Individual
couplings to 119Sn and 117Sn were not resolved so average
values are given. The protons of the meso-phenyl substitu-
ents appear in the spectrum as a AB system with typical
vicinal coupling of ca. 8 Hz. Relative to the parent
b
Sn(1) is the tin atom of the SnCl2TPPS4ꢀ anion; Sn(2) is the tin atom
of the organotin moiety.
an internal reference was prevented by significant interac-
tions, in D2O solution, of all compounds and DSS, as
previously found for H2TPPS4ꢀ salts [8]. While the organo-
metallic moieties are attached to the porphyrin periphery,
Sn(IV) atoms and axially coordinated chloride ions are
present at the centre of porphyrin ring. The favorable
chemical and NMR properties of tin(IV)-porphyrin com-
plexes have enabled the generation of spectroscopic, mainly
NMR; cis- and trans-influence series for oxygen bound
axial ligands of widely differing base strengths.
Dihydroxo-5,10,15,20-tetraphenylporphyrinatotin(IV),
[Sn(IV)(OH)2TPP], has been investigated by H and 13C
1

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C. Pellerito et al. / Journal of Organometallic Chemistry 691 (2006) 1573–1583
Table 6
RT 1H NMR data for diorganotin and triorganotin-Sn(IV)Cl2TPPS (coupling constants are given in Hz; chemical shifts are relative to external DSS;
B0 = 5.87 Ta,b
)
Assignment/compound
H6TPPS
I
II
IIc
III
IV
N–H
n.o.
m-H
8.41d
8.30d
8.27d
8.19m
8.33m
8.25d
8.24d
3J(H,H) 8.0
8.73d
3J(H,H) 8.3
8.47d
3J(H,H) 8.0
8.47d
3J(H,H) 8.0
8.45d
3J(H,H) 7.8
8.45d
o-H
3J(H,H) 8.0
8.99
3J(H,H) 8.3
9.49t
4J(Sn,H) 14.7
3J(H,H) 8.0
9.46t
3J(H,H) 8.0
9.42
4J(Sn,H) n.o.
1.24m,b
1.40m,b
1.86m,b
3J(H,H) 7.8
9.29t
b-pyrrole
RnSn(IV)
9.35t
4J(Sn,H) 14.7
0.83t
4J(Sn,H) 13.1
0.94t
4J(Sn,H) 12.7
0.22t
2J(Sn,H) 95.6
2J(Sn,H) 106
2J(Sn,H) 64.2
CSnC angle
154
174
115
a
H6TPPS = meso-tetra(4-sulfonatophenyl)porphine; I = SnCl2H4TPPS; II = (Me2Sn)2SnCl2TPPS Æ 6H2O; III = (n-Bu2Sn)2SnCl2TPPS Æ 6H2O; IV =
(Me3Sn)4SnCl2TPPS Æ 6H2O.
b
Solvent D2O; DSS external reference; abbreviations: n.o., not observed; i, ipso; o, ortho; m, meta; p, para.
Solvent DMSO-d6; TMS internal reference.
c
1
SnCl2H4TPPS, all complexes show only minor shifts in
chemical shifts, while 4J(Sn,H) are in all instances ca.
15 Hz, suggesting retention of central Sn(IV) diaqua moi-
mal, the H NMR spectrum of (Me2Sn)2SnCl2H2TPPS in
this solvent at fixed 10ꢀ3 concentration, compared with
the D2O counterpart, could give some indication of forma-
tion of aggregates in D2O. Following the formation of
homo-aggregates, high field shifts are expected for b-pyr-
role, ortho and meta protons, the b-pyrrolic signals being
the ones which are shifted the most. Only minor high field
shifts are observed, which may indicate that no major for-
mation of aggregates has taken place. The C–Sn–C angle of
174° is probably due to the coordinating ability of DMSO
towards the organometallic moieties.
1
ety. Several authors [29,32–34] investigated by H NMR
Sn(OH)2 porphyrins in CDCl3 and the high field resonance
at ca. 7.5 ppm assigned to Sn(OH)2 resonance. Since the
complexes presented in this work are not soluble in CDCl3,
the potential hydrolytically generated Sn–OH protons
1
might be detected by H NMR in DMSO-d6 solutions of
all hexahydrated complexes. No high field resonance due
to hydroxo groups has been detected.
Since in the context of a study on the monomer–dimer
equilibrium (homo-dimers) in D2O solutions of H2TPPS4ꢀ
and its Zn2+ and Cu2+ complexes [8] it was shown that,
even for concentrations as high as 0,044 mol dmꢀ3, in
DMSO-d6 the extent of aggregation of monomers is mini-
The organometallic moieties in D2O show coupling con-
2
stants J(117/119Sn,1H) which may be related to the coordi-
nation polyhedron around tin atoms of the organometallic
substituents, by use of the Lockhart and Manders equa-
tions [35].
Table 7
13C NMR data for diorganotin and triorganotin SnCl2[meso-tetra(4-sulfonatophenyl)porphinate] derivatives (coupling constants are given in Hz; chemical
shifts are relative to external DSS; B0 = 5.87 Ta,b
)
Assignment/compound
H6TPPS
I
Ic
II
III
IV
C-p
C-a
C-i
149.69
145.33
139.21
138.66
149.4
145.5
145.2
137.6
148.96
147.41
139.05
137.71
149.6
145.6
145.5
137.8
149.7
146.2
145.7
137.9
149.5
145.8
145.6
137.9
C-o
136.3
C-b
C-m
C-meso
CH3Sn
128.61
126.03
121.78
3J(Sn,C) 23
126.9
127.32
126.74
122.86
136.4
127.1
123.5
9.31
1J(Sn,C) 814
136.5
127.1
n.o.
136.3
127.1
123.4
0.71
1J(Sn,C) 479
123.3
21.8
17.7
CSnC angle
148
119
a
H6TPPS = meso-tetra(4-sulfonatophenyl)porphine; I = SnCl2H4TPPS; II = (Me2Sn)2SnCl2TPPS Æ 6H2O; III = (n-Bu2Sn)2SnCl2TPPS Æ 6H2O; IV =
(Me3Sn)4SnCl2TPPS Æ 6H2O.
b
Solvent D2O; DSS external reference; abbreviations: n.o., not observed; i, ipso; o, ortho; m, meta; p, para.
Solvent DMSO-d6; TMS internal reference.
c

C. Pellerito et al. / Journal of Organometallic Chemistry 691 (2006) 1573–1583
1583
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For (Me2Sn)2SnCl2TPPS, C–Sn–C being 154°, this sug-
gests retention of the distorted trans Me2Sn(IV) octahedral
environment suggested for the complex in the solid state.
Similarly, for (Me3Sn)4SnCl2TPPS, C–Sn–C being 115°,
this suggests a distortion of the ideal trigonal-bipyramidal
geometry of the polymeric solid complex. Relative to the
ammonium derivative of H2TPPS4ꢀ in D2O reported by
1
Corsini [36], the H NMR of H6TPPS closely agrees with
the pattern of resonances found at 100 °C by the authors
and taken as an indication of minimal aggregation. The
spectrum of SnCl2H4TPPS presents, relative to H6TPPS,
a downfield shift of b-pyrrole resonance, due to insertion
of electron withdrawing Sn(IV) ion, while a minor high
field shift of remaining aryl resonances is observed.
´
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3.5. 13C NMR spectra
For the dimethyl- and trimethyltin(IV)SnCl2TPPS com-
plexes, whose solubility in D2O enabled us to obtain
10ꢀ3 M solutions, typical seven-line spectra were observed,
carbon resonances being assigned by chemical shift com-
parison with published literature (Table 7). C–Sn–C values,
derived from the relevant equation [37], of 148° and 119°,
respectively, closely agree with those obtained from 1H
NMR. (n-Butyl)2Sn(IV) derivative, being scarcely soluble
in D2O, afforded poorly resolved resonances which pre-
n
vented evaluation of J(Sn,13C).
3J(Sn,13C) for b-carbons has been observed (23 Hz) for
SnCl2H4TPPS which agrees with the value (30.5 Hz) found
in CDCl3 by Milgrom and Sheppard for SnCl2TPP but not
for Sn(OH)2TPP [29], while it was not discernible in the
organometallic complexes. Resonances of all carbons in
the organometallic complexes show only minor shifts rela-
tive to parent SnCl2H4TPPS, which supports the notion that
coordination to peripheral sulfonato groups brings very lit-
tle perturbation to the macrocycle diamagnetic ring current.
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The financial support by the Ministero della Istruzione,
`
della Universita
e
della Ricerca, (M.I.U.R., CIP
`
2004059078_003), Roma, by Universita di Palermo
(ORPA041443), and Hungarian Research Foundation
(OTKA T032067, T029554 and FKFP 0015/1999) is grate-
fully acknowledged.
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