Metal complexes of 21-(4-tert-butyl-benzenesulfonamido)-5,10,15,20-tetraphenyl-porphyrin: Ga(N-p-NSO2C6H4tBu-tpp)(OH), Tl(N-p-NSO2C6H4tBu-tpp)(O2CCF3) and Zn(N-p-NSO2C6H4tBu-tpp) [tpp = 5,10,15,20-tetraphenylporphyrinate]

Article abstract of DOI:10.1016/j.poly.2005.12.006

The crystal structures of trans-hydroxo-N-p-tert-butylbenzenesulfonylimido-meso-tetraphenylporphyrinatogallium(III) 0.5 aqua and 0.5 methanol solvate [Ga(N-p-NSO₂C₆H₄^tBu-tpp)(OH) · 0.5MeOH · 0.5H₂O; 2 · 0.5MeOH · 0.5H₂O], cis-trifluoroacetato-N-p-tert-butylbenzenesulfonylimido-meso-tetraphenylporphyrinatothallium(III) [Tl(N-p-NSO₂C₆H₄^tBu-tpp)(O₂CCF₃); 3] and N-p-tert-butylbenzenesulfonylimido-meso-tetraphenylporphyrinatozinc(II) 0.7 methanol solvate [Zn(N-p-NSO₂C₆H₄^tBu-tpp) · 0.7MeOH; 4 · 0.7MeOH], were determined. The coordination sphere around Tl³⁺ ion in 3 is a distorted square-based pyramid in which the apical site is occupied by a chelating bidentate CF₃ multiscripts(CO, 2, mml:none(), mml:none(), -) group, whereas for the Ga³⁺ ion in 2, it is a distorted trigonal bipyramid with N(2), N(4), and O(1) lying in the equatorial plane. The geometry around Zn²⁺ in 4 is a distorted square planar. The free energy of activation at the coalescence temperature T_c for the intermolecular trifluoroacetate exchange process for 3 in CD₂Cl₂ is found to be Δ G₂₂₃^? = 46.3 kJ / mol through ¹⁹F NMR variable temperature measurements. In the slow-exchange region, the CF₃ and carbonyl (CO) carbons of the CF₃ multiscripts(CO, 2, mml:none(), mml:none(), -)group of 3 in CD₂Cl₂ are separately located at δ 115.9 [³J(Tl-¹³C) = 155 Hz] and 160.2 [²J(Tl-¹³C) = 81 Hz] at -90 °C.

Full text of DOI:10.1016/j.poly.2005.12.006

Polyhedron 25 (2006) 1864–1872
www.elsevier.com/locate/poly
Metal complexes of 21-(4-tert-butyl-benzenesulfonamido)-5,10,15,
t
20-tetraphenyl-porphyrin: Ga(N-p-NSO2C6H4 Bu-tpp)(OH),
t
t
Tl(N-p-NSO2C6H4 Bu-tpp)(O2CCF3) and Zn(N-p-NSO2C6H4 Bu-tpp)
[tpp = 5,10,15,20-tetraphenylporphyrinate]
a
a
a
a,
*
Wei-Zhi Shil , Kuan-Yu Cho , Ching-Wen Cheng , Jyh-Horung Chen
,
b,
c
d
d
Shin-Shin Wang *, Feng-Ling Liao , Jo-Yu Tung , Hsi-Ying Hsieh ,
e
Shanmugam Elango
a
Department of Chemistry, National Chung-Hsing University, Taichung 40227, Taiwan
b
Union Chemical Laboratories, Hsin-Chu 300, Taiwan
Department of Chemistry, National Tsing-Hua University, Hsin-Chu 300, Taiwan
c
d
Chung Hwa College of Medical Technology, Tainan 717, Taiwan
Institute of Chemical and Engineering Sciences, Singapore 627833, Singapore
e
Received 20 September 2005; accepted 7 December 2005
Available online 20 January 2006
Abstract
The crystal structures of trans-hydroxo-N-p-tert-butylbenzenesulfonylimido-meso-tetraphenylporphyrinatogallium(III) 0.5 aqua and
t
0.5 methanol solvate [Ga(N-p-NSO2C6H4 Bu-tpp)(OH) Æ 0.5MeOH Æ 0.5H2O; 2 Æ 0.5MeOH Æ 0.5H2O], cis-trifluoroacetato-N-p-tert-butyl-
t
benzenesulfonylimido-meso-tetraphenylporphyrinatothallium(III) [Tl(N-p-NSO2C6H4 Bu-tpp)(O2CCF3); 3] and N-p-tert-butylbenzene-
t
sulfonylimido-meso-tetraphenylporphyrinatozinc(II) 0.7 methanol solvate [Zn(N-p-NSO2C6H4 Bu-tpp) Æ 0.7MeOH; 4 Æ 0.7MeOH],
were determined. The coordination sphere around Tl3+ ion in 3 is a distorted square-based pyramid in which the apical site is occupied
by a chelating bidentate CF3CO group, whereas for the Ga3+ ion in 2, it is a distorted trigonal bipyramid with N(2), N(4), and O(1)
ꢀ
2
lying in the equatorial plane. The geometry around Zn2+ in 4 is a distorted square planar. The free energy of activation at the coalescence
temperature Tc for the intermolecular trifluoroacetate exchange process for 3 in CD2Cl2 is found to be DGz ¼ 46:3 kJ=mol through
223
19F NMR variable temperature measurements.
In the slow-exchange region, the CF3 and carbonyl (CO) carbons of the CF3CO2ꢀgroup of 3 in CD2Cl2 are separately located at d
115.9 [3J(Tl–13C) = 155 Hz] and 160.2 [2J(Tl–13C) = 81 Hz] at ꢀ90 ꢀC.
ꢁ 2005 Elsevier Ltd. All rights reserved.
Keywords: Thallium; X-ray diffraction; Gallium; Dynamic NMR; TFA ligands
1. Introduction
porphyrins with M–NX–N linkages [X = Ts = tosyl,
p-COC6H4NO2 (p-nitrobenzoyl), or COC6H5 (benzamido)]
have so far been reported [1–7]. Upon replacement of CH3
Metalloporphyrins with a bridged structure between the
central metal and one of the four pyrrole nitrogens have
drawn much attention in recent times bridged metallo-
t
of tosyl by a bulkier and heavier Bu group, the free base
N-p-HNSO2C6H4CH3-Htpp (tpp = dianion of meso-tetra-
phenylporphyrin) became 21-(4-tert-butyl-benzenesulfo-
namido)-5,10,15,20-tetraphenyl-porphyrin N-p-HNSO2-
C6H4 Bu-Htpp (1). The d10 configuration permits a wide
t
*
Corresponding authors.
E-mail address: jyhhchen@dragon.nchu.edu.tw (J.-H. Chen).
variety of geometries and coordination numbers. However
0277-5387/$ - see front matter ꢁ 2005 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2005.12.006

W.-Z. Shil et al. / Polyhedron 25 (2006) 1864–1872
1865
there were no X-ray structural data available for the metal
ion [M(II) and M(III)] complexes of N-p-HNSO2C6H4 Bu-
Removal of the solvent and recrystallization from
CH2Cl2–MeOH [1:3 (v/v)] gave the bluish-purple solid of
t
Htpp (1). The effect of coordination of a variety of d10 metals
namely zinc(II), gallinum(III) and thallium(III) on pophyrin
macrocycles is of great interest, because the structural anal-
ysis of these metal complexes could be expected to discover
the effects due to the incorporation of d10 metal ions (i.e.,
Zn2+, Ga3+ and TI3+) into the highly distorted and relatively
rigid coordination environment provided by the aminated
1 (0.17 g, 2.06 · 10ꢀ4 mol, 68%). H NMR (599.95 MHz,
1
CDCl3, 20 ꢀC): d 8.97 [d, Hb, 3J(H–H) = 5 Hz]; 8.93
3
3
[d, Hb, J(H–H) = 5 Hz]; 8.81 (s, Hb); 8.46 [d, J(H–H) =
7 Hz] and 8.10 [d, 3J(H–H) = 8 Hz] for ortho protons;
7.91(s, Hb); 7.87–7.81 (m) and 7.78–7.73 (m) for meta
t
3
and para protons; 6.65 [d, BuBS-H3,5, J(H–H) = 8 Hz],
where tBuBS = 4-tert-butylbenzenesulfonyl; 4.94 [d,
t
3
porphyrin ligand 1. The bulky Bu group in this system
tBuBS-H2,6, J(H–H) = 8 Hz]; 1.13 (s, t-butyl protons); 0
enhances the crystallization of metal these complexes.
In this paper, we described the synthesis and X-ray struc-
tural investigation on the metallation of 1 leading to mono-
nuclear complexes of trans-hydroxo-N-p-tert-butylbenzene-
sulfonylimido-meso-tetraphenylporphyrinatogallium(III) 0.5
(s, NH). FAB-MS, m/z (assignment, rel intensity): 826
([N-p-HNSO2C6H4 Bu-Htpp)]+, 100), 614([(H2tpp)]+,
t
93.89). UV/visible spectrum, k (nm) [e · 10ꢀ3 (Mꢀ1 cmꢀ1)]
in CH2Cl2: 320 (24.7), 433 (339), 548 (15.0), 584 (15.9),
638 (13.7).
t
aqua and 0.5 methanol solvate [Ga(N-p-NSO2C6H4 Bu-tpp)
t
2.2. Ga(N-p-NSO2C6H4 Bu-tpp)(OH) (2)
(OH) Æ 0.5MeOH Æ 0.5H2O; 2 Æ 0.5MeOH Æ 0.5H2O], cis-tri-
fluoroacetato-N-p-tert-butylbenzenesulfonylimido-meso-tet-
t
t
raphenylporphyrinatothallium(III) [Tl(N-p-NSOC6H4 Bu-
Free base N-p-HNSO2C6H4 Bu-Htpp (1) (0.05 g,
tpp)(O2CCF3); 3] and N-p-tert-butylbenzenesulfonylimido-
meso-tetraphenylporphyrinatozinc(II) 0.7 methanol solvate
6.05 · 10ꢀ5 mol) and Ga2O3 (0.1 g, 5.34 · 10ꢀ4 mol) were
refluxed for 12 h in 100 cm3 of acetic acid containing
sodium acetate (0.05 g). After removal of the solvent
(HOAc) under reduced pressure, the residue was dissolved
in CH2Cl2 and then dried over Na2SO4. After filtration, the
filtrate was rotavaped and recrystallization from CH2Cl2/
MeOH [1:3 (v/v)] afforded a purple solid of 2 (0.036 g,
3.95 · 10ꢀ5 mol, 65%). Compound 2 was dissolved in
CH2Cl2 and layered with MeOH to get purple crystals of
t
[Zn(N-p-NSO2C6H4 Bu-tpp) Æ 0.7MeOH; 4 Æ 0.7MeOH]. It
˚
is observed that the ionic radius increases from 0.69 A for
2+
Ga3+ to 0.74 A for Zn and to 1.025 A for Tl3+ [8]. Further-
˚
˚
more, we tried to figure out the relative positions of the
CF3CO (or OHꢀ) and N-tBuBS (tBuBS = 4-tert-butyl-
ꢀ
2
t
benzenesulfonyl = SO2C6- H4 Bu) groups coordinated to
the metal atom lead to a cis configuration in 3 and a trans
configuration in 2 that might depend on the ionic radius of
the Tl3+ and Ga3+. In addition, the trifluoroacetato (TFA)
exchange of Tl(tpp)(O2CCF3) observed in THF-d8
prompted us to investigate a similar intermolecular exchange
for complex 3 in CD2Cl2 by 19F and 13C dynamic NMR
methods [9].
2
for single crystal X-ray analysis. 1H NMR
(599.95 MHz, CDCl3, 20 ꢀC): d 9.22 [s, Hb(4,5)], Hb(a,b)
represents the two equivalent b-pyrrole protons attached
to carbons a and b, respectively; 8.75 [d, Hb(10,19),
3
3J(H–H) = 4.8 Hz]; 8.71 [d, Hb(9,20), J(H–H) = 4.8 Hz];
7.85 [s, Hb(14,15)]; 8.36 [s, o0-H(38,40)], o0-H represents
ortho phenyl protons; 8.06 [d, o0-H(34,44), 3J(H–H) =
4.3 Hz]; 8.34 [m, o-H(26,28)]; 8.29 [d, o-H(22,32),
3J(H–H) = 5.4 Hz]; 7.74–7.85 (m) for meta and para pro-
2. Experimental
tons; 6.58 [d, tBuBS-H3,5 or H(47,49), 3J(H–H) =
,
t
2.1. N-p-HNSO2C6H4 Bu-Htpp (1)
8.4 Hz]; 4.72 [d, tBuBS-H2,6, or H(46,50), 3J(H–H) =
8.4 Hz]; 1.03 (s, t-butyl protons); ꢀ1.98 (s, OH). FAB-MS,
m/z (assignment, rel intensity): 894 ([Ga(N-p-
A mixture of NaN3 (1 g, 1.54 · 10ꢀ2 mol) in distilled
water (2 cm3) and N-4-tert-butylbenzenesulfonyl chloride
(1 g, 4.31 · 10ꢀ3 mol) in acetone (20 cm3) was stirred for
1 h. After concentration, the residue was taken in CH2Cl2
and collected by filtration to remove the excess of NaN3.
The CH2Cl2 layer contains p-tBu-C6H4-SO2N3. A solution
NSO2C6H4 Bu-tpp)]+, 11.19), 892 ([Ga(N-p-NSO2C6H4-
t
tBu-tpp) ꢀ 2H]+, 11.90), 681 ([Ga(tpp)-H]+, 49.40), 154
([NBA + H]+, 68.01). UV/visible spectrum,
k (nm)
[e · 10ꢀ3 (Mꢀ1 cmꢀ1)] in CH2Cl2: 434 (315), 547 (11.4),
t
of Zn(tpp) (0.27 g, 3.04 · 10ꢀ4 mol) and the above Bu-
585 (14.6), 634 (4.3).
C6H4-SO2N3 in CH2Cl2 (200 cm3) in a stoppered 250 mL
Erlenmeyer flask was left for ca. 8 h in the sunlight. After
that to this solution was added 0.5 N HCl (250 cm3) with
vigorous shaking for 0.5 h. The organic layer was sepa-
rated, solid ammonium carbonate was added to it, and
then dried with anhydrous Na2SO4. The excess (NH4)2CO3
and Na2SO4 were removed by filtration. After concentra-
tion, the residue was dissolved in a minimum of CH2Cl2
and chromatographed on silica gel (100 g, 70–230 mesh).
The desired compound was eluted with ethyl acetate–
CH2Cl2 [1:2 (v/v)] as dark brown band on silica gel.
t
2.3. Tl(N-p-NSO2C6H4 Bu-tpp)(O2CCF3) (3)
A mixture of Tl(O2CCF3)3 (0.07 g, 1.29 · 10ꢀ4 mol) in
MeOH (10 cm3) and N-p-HNSO2C6H4 Bu-Htpp (0.05 g,
t
6.05 · 10ꢀ5 mol) in CH2Cl2 (20 cm3) was refluxed in
CH3CN (50 cm3) for 3 h. After concentrating, the residue
was dissolved in CH2Cl2, dried with anhydrous Na2SO4
and filtered. The filtrate was concentrated and recrystal-
lized from CH2Cl2–MeOH [1:5 (v/v)] yielding blue solid
of 3 (0.035 g, 3.07 · 10ꢀ5mol, 50.7%) which was again

1866
W.-Z. Shil et al. / Polyhedron 25 (2006) 1864–1872
dissolved in CH2Cl2 and layered with MeOH to get blue
crystals for single crystal X-ray analysis. 1H NMR
(299.96 MHz, CD2Cl2, 20 ꢀC): d 9.16 [d d, Hb(10,19),
4J(Tl–H) = 17.5 Hz and 3J(H–H)] = 4.8 Hz; 9.03 [d d,
Hb(9,20), 4J(Tl–H) = 10.3 Hz and 3J(H–H) = 4.8 Hz];
H(47,49), 3J(H–H) = 8 Hz]; 5.58 [d, tBuBS-H2,6
, or
H(46,50), 3J(H–H) = 8 Hz]; 1.15 (s, t-butyl protons).
ESI-MS, m/z (assignment, rel intensity): 888 ([Zn(N-p-
NSO2C6H4 Bu-tpp) + H]+, 22.08), 690 ([Zn(tpp)+N ꢀ
t
2H]+, 100). UV/visible spectrum,
k
(nm) [e · 10ꢀ3
4
8.81 [d, Hb(4,5), J(Tl–H) = 90.0 Hz]; 7.03 [s, Hb(14,15)];
(Mꢀ1 cmꢀ1)] in CH2Cl2: 322 (20.5), 437 (299), 557 (9.9),
603 (16.1).
8.38 [d, o-H(26,32), 3J(H–H) = 5.4 Hz]; 8.15 [d, o-H(22,
3
28), J(H–H) = 6.6 Hz]; 7.80–7.90 (m) for meta and para
protons; 7.13 [d, tBuBS-H3,5, or H(47,49), 3J(H–H) =
8.0 Hz]; 6.13 [d, tBuBS-H2,6, or H(46,50), 3J(H–H) =
8.0 Hz]; 1.19 (s, t-butyl protons). 19F NMR (564.49 MHz,
CD2Cl2, 20 ꢀC): d ꢀ73.50 (s). FAB-MS, m/z (assignment,
2.5. Spectroscopy
Proton and 13C NMR spectra were recorded at 299.95
(or 599.95) and 75.43 (or 150.87) MHz, respectively, on
Varian VXR-300 (or Varian Unity Inova-600) spectrome-
ters locked on deuterated solvent, and referenced to the sol-
vent peak. Proton NMR is relative to CD2Cl2 or CDCl3 at
d = 5.30 or 7.24 and 13C NMR to the center line of CD2Cl2
or CDCl3 at d = 53.6 or 77.0. 19F NMR spectra were mea-
sured in CD2Cl2 at 564.49 MHz in a Varian Unity Inova-
600 spectrometer. 19F NMR data are internally referenced
to CFCl3. The temperature of the spectrometer probe was
calibrated by the shift difference of the methanol resonance
in the 1H NMR spectrum. HMQC (heteronuclear multiple
quantum coherence) was used to correlate protons and
carbon through one-bond coupling and HMBC (heteronu-
clear multiple bond coherence) for two- and three-bond
proton–carbon coupling. nuclear Overhauser effect
(NOE) difference spectroscopy was employed to determine
the 1H–1H proximity through space over a distance of
rel intensity): 1028 ([Tl(N-p-NSO2C6H4 Bu-tpp)]+, 39.58),
t
826 ([HN-p-NSO2C6H4 Bu-Htpp]+, 54.23), 154 ([NBA+
t
H]+, 100). UV/visible spectrum, k (nm) [e · 10ꢀ3 (Mꢀ1
cmꢀ1)] in CH2Cl2: 336 (18.2), 447 (259), 556 (6.55), 608
(14.6).
t
2.4. Zn(N-p-NSO2C6H4 Bu-tpp) (4)
Compound 4 was prepared in the same way as described
t
for Tl(N-p-NSO2C6H4 Bu-tpp)(OAc) using Zn(OAc)2 in
80% yield [14]. Compound 4 was dissolved in CH2Cl2 and
layered with MeOH and purple crystals of 4 Æ 0.7MeOH were
obtained for single crystal X-ray analysis. 1H NMR
(599.95 MHz, CDCl3, 20 ꢀC):
d 8.96 [d, Hb(7,18),
3
3J(H–H) = 4.2 Hz]; 8.90 [d, Hb(8,17), J(H–H) = 4.8 Hz];
8.82 [s, Hb(12,13)]; 8.46 [d, o-H(32,34), 3J(H–H) = 7.2 Hz];
3
˚
8.10 [d, o-H(28,38), J(H–H) = 7.2 Hz]; 8.21 (bs) and 7.89
up to about 4 A.
(bs) for the other set of ortho protons (o0-H); 7.85
[t,3J(H–H) = 7.8 Hz], 7.74 (m) and 7.68 (bs) for meta protons;
Positive ion mode ESI mass spectra were acquired at
room temperature on a ThermoFinnigan LCQ Advantage
mass spectrometer. The positive-ion fast atom bombard-
3
t
7.81 [t, para H, J(H–H) = 7.8 Hz]; 6.89 [d, BuBS-H3,5, or
Table 1
Crystal data for 2 Æ 0.5MeOH Æ 0.5H2O, 3 and 4 Æ 0.7MeOH
Empirical formula
C
54.50H45GaN5O4S
C56H41F3N5O4STl
(3)
1141.37
C54.70H43.80N5O2.70SZn
(4 Æ 0.7MeOH)
911.78
(2 Æ 0.5MeOH Æ 0.5H2O)
935.73
Formula weight
Space group
ꢀ
ꢀ
P1
P1
P21/c
Crystal system
triclinic
10.6962(6)
13.3596(8)
18.3789(11)
72.373(1)
87.530(1)
67.930(1)
2312.1(2)
2
triclinic
12.2694(7)
14.4713(8)
14.5566(8)
79.540(1)
70.512(1)
86.048(1)
2395.9(2)
2
monoclinic
14.8830(18)
12.2593(16)
25.427(3)
90
100.010(2)
90
4568.7(10)
4
˚
a (A)
˚
b (A)
˚
c (A)
a (ꢀ)
b (ꢀ)
c (ꢀ)
3
˚
V (A )
Z
F(000)
972
1.344
0.693
1136
1.582
3.480
1916
1.338
0.635
Dcalc (g cmꢀ3
)
l(Mo Ka) (mmꢀ1
)
S
1.003
0.30 · 0.25 · 0.25
56.68
1.006
0.50 · 0.20 · 0.10
56.60
1.082
0.68 · 0.32 · 0.18
52.16
Crystal size (mm3)
2hmax (ꢀ)
T (K)
100(2)
100(2)
295(2)
Number of reflections measured
Number of reflections observed
11429
8285
0.0522
0.1476
11836
10564 (I > 2r(I))
0.0292
9005
5133 (I > 2r(I))
0.0493
a
R1
wR2
b
0.0711
0.1261
P
P
a
R1 ¼ ½ jjF oj ꢀ jF cjj= jF ojꢁ.
P
P
2
2 1=2
b
wR2 ¼ ½ wðF 2o ꢀ F c2Þ = wðF 2oÞ ꢁ
.

W.-Z. Shil et al. / Polyhedron 25 (2006) 1864–1872
1867
Table 2
3. Results and discussion
˚
Selected bond lengths (A) and angles (ꢀ) for compounds 2 Æ 0.5MeOH Æ
0.5H2O, 3 and 4 Æ 0.7MeOH
3.1. Molecular structures of 2 Æ 0.5MeOH Æ 0.5H2O,
3 and 4 Æ 0.7MeOH
t
Ga(N-p-NSO2C6H4 Bu-tpp)(OH) Æ 0.5MeOH Æ 0.5H2O
(2 Æ 0.5MeOH Æ 0.5H2O)
Bond lengths
The X-ray structures are depicted in Fig. 1a for the com-
plex Ga(N-p-NSO2C6H4 Bu-tpp)(OH) Æ 0.5MeOH Æ 0.5H2O
Ga(1)–N(1)
Ga(1)–N(2)
Ga(1)–N(3)
2.305(2)
1.914(2)
2.048(2)
Ga(1)–N(4)
Ga(1)ꢂ ꢂ ꢂN(5)
Ga(1)–O(1)
1.959(2)
2.638(2)
1.835(2)
t
(or 2 Æ 0.5MeOH Æ 0.5H2O), in Fig. 1b for Tl-
t
(N-p-NSO2C6H4 Bu-tpp)(O2CCF3) 3 and in Fig. 1c for Zn-
Bond angles
t
O(1)–Ga(1)–N(1)
O(1)–Ga(1)–N(2)
O(1)–Ga(1)–N(3)
O(1)–Ga(1)–N(4)
Ga(1)–N(4)–S(1)
90.40(9)
118.66(10)
95.65(10)
114.13(10)
140.11(14)
Ga(1)–N(4)–N(5)
N(4)–Ga(1)–N(1)
N(4)–Ga(1)–N(2)
N(4)–Ga(1)–N(3)
102.95(16)
84.38(10)
127.18(10)
83.33(9)
(N-p-NSO2C6H4 Bu-tpp) Æ 0.7MeOH (4 Æ 0.7MeOH). Their
structures are a five-coordinate gallium, a six-coordinate
thallium, and a four-coordinate zinc, having three nitrogen
atoms of the porphyrins and one extra nitrogen atom of the
t
NSO2C6H4 Bu fragment in common, but they are different
t
ꢀ
Tl(N-p-NSO2C6H4 Bu-tpp)(O2CCF3) (3)
Bond lengths
with one more chelating bidentate CF3CO2 ligand for 3 in
the axial site and one more axial OHꢀ ligand for 2. The
metal–ligand bond distances, i.e., from Ga(III), Tl(III),
and Zn(II) atoms to the ligand and the angles are summa-
rized in Table 2. The bond distances are Ga(1)–
Tl(1)–O(3)
Tl(1)–O(4)
Tl(1)–N(1)
2.426(2)
2.427(2)
2.363(2)
Tl (1)–N(2)
Tl (1)–N(3)
Tl(1)ꢂ ꢂ ꢂN(4)
Tl (1)–N(5)
2.120(2)
2.329(2)
2.880(2)
2.081(2)
˚
˚
O(1) = 1.835(2) A and the mean Ga(1)–N(p) = 1.969(2) A
Bond angles
for 2 Æ 0.5MeOH Æ 0.5H2O; for 3, the similar values are
O(3)–Tl(1)–N(1)
O(3)–Tl(1)–N(2)
O(3)–Tl(1)–N(3)
O(3)–Tl(1)–N(5)
O(3)–Tl(1)–O(4)
136.05(8)
93.64(9)
103.77(9)
110.86(9)
54.30(8)
O(4)–Tl(1)–N(1)
O(4)–Tl(1)–N(2)
O(4)–Tl(1)–N(3)
O(4)–Tl(1)–N(5)
Tl(1)–N(5)–N(4)
83.83(8)
102.20(9)
157.44(9)
97.07(8)
˚
˚
Tl(1)–O(3) = 2.426(2) A, Tl(1)–O(4) = 2.427(2) A and the
˚
mean Tl(1)–N(p) = 2.223(2) A. The interaction of the tri-
fluoroacetate with thallium is chelating bidentate. This
kind of bidentate interaction was previously observed for
110.84(17)
˚
t
Tl(tpp)(O2CCF3) with Tl–O(1) = 2.309(7) A and Tl–
Zn(N-p-NSO2C6H4 Bu-tpp) Æ 0.7MeOH (4 Æ 0.7MeOH)
Bond lengths
˚
O(2) = 2.64(1) A [9]. Hence, the geometry around Tl is a
Zn–N(2)
Zn–N(3)
Zn–N(4)
2.074(3)
1.943(3)
2.060(3)
Zn–N(5)
Zn–O(3)
Znꢂ ꢂ ꢂN(1)
1.983(3)
2.342(6)
2.627(6)
distorted square-base pyramid in which theꢀapical site is
occupied by a chelating bidentate CF3CO2 group. The
˚
˚
bond distance (A) of Zn–O(3) is 2.342(6) A and the mean
˚
Bond angles
Zn–N(p) = 2.015(3) A for 4 Æ 0.7MeOH. The Zn–O(3)-
(MeOH) distance of 2.342(6) A is longer than the sum of
the covalent radii of Zn and O (1.93 A) but is shorter than
N(5)–Zn–N(2)
N(5)–Zn–N(3)
N(5)–Zn–N(4)
90.08(11)
171.74(11)
88.70(11)
Zn–N(5)–N(1)
Zn–N(5)–S
100.50(18)
144.29(16)
˚
˚
˚
the sum of the Van der Waals radii of Zn and O (2.90 A)
[8]. This longer Znꢂ ꢂ ꢂO(3) contact is too long to be consid-
ered as a true coordinated bond and may be viewed as a
secondary intermolecular interaction. Hence, the geometry
around Zn2+ is a distorted square planar in 4. The
observed H(3)ꢂ ꢂ ꢂO(1) and O(1)ꢂ ꢂ ꢂO(3) distances were 2.16
ment mass spectrum (FAB MS) was obtained in a nitrob-
enzyl alcohol (NBA) matrix using a JEOL JMS-SX/SX
102A mass spectrometer. UV/visible spectra were recorded
at 20 ꢀC on a HITACHI U-3210 spectrophotometer.
˚
and 2.69 A, respectively. These distances fall below those
expected from Van der Waals distances of 2.60 and
˚
2.6. Crystallography
2.80 A, respectively. The O(1)–H(3)–O(3) angle was
158.5ꢀ and its deviation from linearity was not too severe.
Therefore, a hydrogen bond exists between H(3) and the
O(1) atom in 4.
Table 1 presents the crystal data as well as other infor-
mation for 2 Æ 0.5MeOH Æ 0.5H2O, 3, and 4 Æ 0.7MeOH.
Measurements were taken on a Bruker AXS SMART-
1000 diffractometer using monochromatized Mo Ka radia-
The distortion in five-coordinate complexes can be
quantified by the ‘‘degree of trigonality’’ which is defined
as s = (b ꢀ a)/60, where ‘b’ is the largest and ‘a’ the second
largest of the Lbasal–M–Lbasal angles [10,11]. The limiting
values are s = 0 for an ideal tetragonal geometry and
s = 1 for an ideal trigonal-bipyramid. In the present case,
we find b = 167.66(9)ꢀ [N(1)–Ga–N(3)] and a =
127.18(10)ꢀ [N(2)–Ga(1)–N(4)] for 2 Æ 0.5MeOH Æ 0.5H2O.
Thus, a value of s = 0.67 is obtained for 2 Æ 0.5MeOH Æ
0.5H2O. Hence the geometry around Ga(III) is best
described as a distorted trigonal bipyramid (or a square-
based pyramidal distorted trigonal bipyramid, SBPDTBP)
˚
tion (k = 0.71073 A). Empirical absorption corrections
were made for 2 Æ 0.5MeOH Æ 0.5H2O and 3. The SADABS
absorption corrections were made for 4 Æ 0.7MeOH. The
structures were solved by direct methods (SHELXTL PLUS)
and refined by the full-matrix least-squares method. All
non-hydrogen atoms were refined with anisotropic thermal
parameters, whereas all hydrogen atoms were placed in cal-
culated positions and refined with a riding model. Table 2
lists selected bond distances and angles for these three
complexes.

1868
W.-Z. Shil et al. / Polyhedron 25 (2006) 1864–1872
t
Fig. 1. Molecular configuration and atom-labeling scheme for (a) Ga(N-p-NSO2C6H4 Butpp)(OH) Æ 0.5MeOH Æ 0.5H2O [2 Æ 0.5MeOH Æ 0.5H2O],
t
t
(b) Tl(N-p-NSO2C6H4 Bu-tpp)(O2CCF3) 3 and (c) Zn(N-p-NSO2C6H4 Bu-tpp) Æ 0.7MeOH [4 Æ 0.7MeOH], with ellipsoids drawn at 30% probability.
Hydrogen atoms for all compounds are omitted for clarity.
˚
with N(2), N(4), and O(1) lying in the equatorial plane for
2 Æ 0.5MeOH Æ 0.5H2O [12].
and N(5) are located on the same side at 1.14 and 1.41 A
from its (3N) plane, but for complex 2, Ga3+ and N(4)
˚
The pyrrole nitrogens N(5), N(4), and N(1) are no
longer bonded to gallium, thallium, and zinc as indicated
are located on different sides at ꢀ0.17 and 1.27 A from
its (3N) plane, [cf. the corresponding displacement of
˚
˚
˚
by their longer internuclear distances, 2.638(2) A for
0.51 A for Zn and 1.30 A for N(5) in 4]. Apparently, chelat-
ing bidentate trifluoroacetate in is cis to the
NSO2C6H4 Bu group with O(3) and O(4) being located sep-
arately at 3.17 and 3.01 A out of the 3N plane and monod-
entate hydroxide in 2 is trans to the NSO2C6H4 Bu group
˚
˚
Ga(1)ꢂ ꢂ ꢂN(5), 2.880(2) A for Tl(1)ꢂ ꢂ ꢂN(4) and 2.627(6) A
for Znꢂ ꢂ ꢂN(1). We adopt the plane of three strongly bound
pyrrole nitrogen atoms [i.e., N(1), N(2), and N(3) for 2, 3
and N(2), N(3), and N(4) for 4] as a reference plane 3N.
Because of the larger size of the Tl3+ in complex 3, T3+
3
t
˚
t
˚
with O(1) located at ꢀ1.86 A out of the 3N plane.

W.-Z. Shil et al. / Polyhedron 25 (2006) 1864–1872
1869
Table 3
1H,13C NMR and X-ray data for complexes 2, 3 and 4
1H NMR (ppm)
tBuBS-H3,5
13C NMR (ppm)
˚
Compound
rion (A)
X-ray
D(3N)a (A)
hb (ꢀ)
tBuBS-H2,6
tBu
DCb
c
˚
Ga3+ in 2
Zn2+ in 4
Tl3+ in 3
a
0.69
0.74
1.025
0.17
0.51
1.14
26.7
39.6
41.9
6.58
6.89
7.13
4.72
5.58
6.13
1.03
1.15
1.19
10–15
15–17
17–21
D(3N) denotes the displacement of the metal center from the 3N plane.
b
c
t
h: dihedral angle between the pyrrole ring bearing a NSO2C6H4 Bu group and the 3N plane.
DCb = dCb (bearing a NSO2C6H4 Bu group) ꢀ dCb (without bearing a NSO2C6H4 Bu group).
t
t
1
The porphyrin macrocycle is indeed distorted because of
the presence of the NSO2C6H4 Bu group. Thus, the N(5)
3.2. H and 13C NMR for (2) and (4) in CDCl3 and
(3) in CD2Cl2
t
(in 2), N(4) (in 3) and N(1) (in 4) pyrrole rings bearing
the NSO2C6H4 Bu group would be deviated mostly from
t
1
Complexes 2, 3 and 4 were characterized by H (Fig. 2)
the 3N plane and oriented separately in a dihedral angle
of 26.7ꢀ, 41.9ꢀ, and of 39.6ꢀ, whereas small angles of 6.9ꢀ,
5.0ꢀ, and 8.6ꢀ occur with N(1), N(2), and N(3) pyrroles
for 2 Æ 0.5MeOH Æ 0.5H2O, and 11.6ꢀ, 7.9ꢀ, and 2.1ꢀ occur
with N(1), N(2), and N(3) pyrroles for 3, and 9.2ꢀ, 11.0ꢀ
and 5.0ꢀ occur with N(2), N(3), and N(4) pyrroles for
4 Æ 0.7MeOH. In complex 2 Æ 0.5MeOH Æ 0.5H2O, such a
large deviation from planarity for the N(5) pyrrole is also
reflected by observing a 10–15 ppm upfield shift of the
Cb(C14,C15) at 120.1 ppm compared to 135.2 ppm for
Cb(C10,C19), 133.2 ppm for Cb(C4,C5) and 129.7 ppm
for Cb(C9,C20). In compound 3, a similar deviation is
found for the N(4) pyrrole by observing a 17–21 ppm
upfield shift of the Cb(C14,C15) at 116.0 ppm compared
to 136.8 for Cb(C10,C19), 134.0 ppm for Cb(C9,C20), and
132.6 ppm for Cb(C4,C5). In compound 4, a similar devia-
tion is also found for the N(1) pyrrole by observing a
15–17 ppm upfield shift of the Cb(C2,C3) at 117.6 ppm
compared to 134.6 for Cb(C7,C18), 132.5 ppm for
Cb(C12,C13) and 132.4 ppm for Cb(C8,C17). Similar kind
of upfield shifts of Cb resonances due to the non-planarity
of porphyrin were also observed with a magnitude of
15–17 ppm for Zn(N-NTs-tpp) and 16–21 ppm for Tl-
and 13C NMR spectra. In solution, the molecule has effec-
tive CS symmetry with a mirror plane running through the
N(2)–Ga(1)–N(4)–N(5) unit for 2 or the N(2)–Tl(1)–N(5)–
N(4) unit for 3 or N(3)–Zn–N(5)–N(1) unit for 4. There are
four distinct b-pyrrole protons Hb, four b-pyrrole carbons
Cb, four a-pyrrole carbons Ca, two different meso carbons
Cmeso, and two phenyl-C1 carbons for all the three com-
plexes. The NMR study of 3 showed four different types
of Tl–H coupling constants for Hb in CD2Cl2 at 20 ꢀC
(Fig. 2b). The doublet at 8.81 ppm is assigned to Hb(4,5)
4
with J(Tl–H) = 90 Hz and the singlet at 7.03 ppm is due
to Hb(14,15). The doublet of a doublet at 9.16 ppm is
due to Hb(10,19) with 4J(Tl–H) = 17.5 Hz and 3J(H–
H) = 4.8 Hz and the doublet of a doublet at 9.03 ppm is
due to Hb(9,20) with 4J(Tl–H) = 10.3 Hz and 3J(H–
H) = 4.8 Hz. Likewise, there were also four different types
of Tl–13C coupling constants for Cb in 3. The doublet at
3
132.6 ppm is due to Cb(C4,C5) with J(Tl–13C) = 198 Hz
and the doublet at 136.8 ppm is due to Cb(C10,C19) with
3J(Tl–13C) = 35 Hz. The singlet at 134.0 ppm is due to
Cb(C9,C20) with 3J(Tl–13C) being unobserved and the dou-
blet at 116.0 ppm is due to Cb(C14,C15) with
1
4J(Tl–13C) = 88 Hz. The H NMR spectra reveal that the
t
(N-NTs-tpp)(OAc) [2,3]. In a nutshell, as the ionic radius
aromatic protons of the BuBS group appear as two dou-
3+
increases from 0.69 A for Ga , 0.74 A for Zn2+, to
blets at 6.58 (tBuBS – H3,5) and at 4.72 ppm (tBuBS –
˚
˚
1.025 A for Tl3+, the bending of pyrrole ring bearing a
NSO2C6H4 Bu group increases from 2, 4 to 3. Hence, the
H2,6) for 2 (Fig. 2a) and at 7.13 (d) and 6.13 (d) ppm for
3 (Fig. 2b).
˚
t
dihedral angles (h) between the sharply bent pyrrole ring
and the 3N plane increases from 26.7ꢀ in the gallium com-
plex, 39.6ꢀ in the zinc complex, to 41.9ꢀ in the thallium
complex (Table 3). Such a large bending from planarity is
also reflected by observing the amount of the upfield shift
for the Cb of the sharply bent pyrrole ring (i.e., DCb). This
DCb increases from 10–15 ppm for 2, 15–17 ppm for 4, to
17–21 ppm for 3 (Table 3). The dihedral angles between
the mean plane of the skeleton (3N) and the planes of
the phenyl groups are 71.5ꢀ [C(24)], 69.6ꢀ [C(30)], 55.7ꢀ
[C(36)], and 56.3ꢀ [C(42)] for 2 Æ 0.5MeOH Æ 0.5H2O and
56.5ꢀ [C(24)], 83.5ꢀ [C(30)], 46.6ꢀ [C(36)], and 34.9ꢀ
[C(42)] for 3 and the corresponding angles are 52.5ꢀ,
55.1ꢀ, 87.5ꢀ, and 47.2ꢀ for 4 Æ 0.7MeOH.
Due to the porphyrin ring current effect, all NSO2
t
C6H4 Bu and hydroxo protons are shifted upfield com-
t
pared to their counterparts in free NSO2C6H4 Bu and
OHꢀ. The above ring current effect indicates that the
t
NSO2C6H4 Bu group is bonded to Zn in 4 and to Tl
in 3 and both the NSO2C6H4 Bu and the OHꢀ ligands
t
are bonded to Ga in 2 in solution phase. The NSO2-
t
C6H4 Bu bonding argument is further corroborated by
the result that the tBuBS-C1 [i.e., C(45)] in 3 was
3
observed at 137.7 ppm with J(Tl–C) = 52 Hz. X-ray dif-
fraction analysis unambiguously confirms that 3 is a
bidentate complex in the solid phase. Broadly, by
3+
˚
˚
increasing D(3N) from 0.17 A for (Ga in 2), 0.51 A for
(Zn2+ in 4) to 1.14 A for (Tl in 3), the d(tBuBS-H2,6
)
3+
˚

1870
W.-Z. Shil et al. / Polyhedron 25 (2006) 1864–1872
Fig. 2. 1H NMR spectra for (a) 2 in CDCl3 at 599.95 MHz and (b) 3 in CD2Cl2 at 299.96 MHz.
shifts from 4.72, 5.58 to 6.13 ppm and d(tBuBS-H3,5
shifts from 6.58, 6.89 to 7.13 ppm (Table 3). The ring
)
results suggest that as the protons of the tBuBS are
located on metal with a large D3N, they move away
from the geometrical center Ct of 4N for the complexes
2, 3 and 4. Hence, the shielding of the ring current effect
from the 18p electrons becomes smaller and the 1H
chemical shifts are relatively less upfield than those with
a smaller D3N.
1
t
current effect for the H resonances of the BuBS protons
t
decreases with an increase in the distance between BuBS
protons and Ct. The geometrical center (Ct) is the center
of the mean plane of the 4N atoms core [i.e., N(1), N(2),
N(3) and N(5) for 2, N(1)–N(4) for 3 and 4]. The above

W.-Z. Shil et al. / Polyhedron 25 (2006) 1864–1872
1871
For ortho protons, at 20 ꢀC, the rotation of phenyl
group along C1–Cmeso bond for 2 in CDCl3 is intermedi-
ately slow which is evident from the appearance of the
two sets of doublet, one multiplet and one singlet due to
four different ortho protons of aromatic ring (Fig. 2a)
[13]. For these ortho protons in 2, we attribute one multi-
plet at 8.34 ppm to ortho protons o-H(26,28), the doublet
Moreover, no signal of CF3 carbons has been found for
3 in CD2Cl2 at 20 ꢀC. At ꢀ90 ꢀC, the rate of intermolecular
ꢀ
exchange of CF3CO2 for 3 in CD2Cl2 is slow. Hence, at
ꢀ
this temperature, the CO and CF3 carbons of CF3CO2
2
in 3 are observed at d 160.2 ppm [with J(F–C) = 40 and
2J(Tl–C) = 81 Hz] and 115.9 ppm [1J(F–C) = 290 and
3J(Tl–C) = 155 Hz], respectively. These 13C resonances
are quite close to that of trifluroacetato-N-tosylimido-
meso-tetraphenylporphyrinatothallium(III) Tl(N-NTs-tpp)-
(O2CCF3) 5 in which the two corresponding carbons were
3
at 8.29 ppm to ortho protons o-H(22,32) with J(H–H) =
5.4 Hz, one singlet at 8.36 ppm due to ortho protons
o0-H(38,40) and the other doublet at 8.06 ppm is assigned
to ortho protons o0-H(34,44) with 3J(H–H) = 4.3 Hz
(Fig. 2a). This rotation of the phenyl group along C1–Cmeso
[C(7)–C(27) or C(2)–C(21)] bond for 3 in CD2Cl2 at 20 ꢀC
is also intermediately slow. This intermediately slow rota-
tion is supported by the two doublets at 8.38 and
8.15 ppm due to o-H(26,32) and o-H(22,28), respectively.
Moreover, the rotation of phenyl group along the C(12)–
C(33) [or C(17)–C(39)] bond for 3 is at the intermediate
exchange region. In this intermediate exchange region,
the signals are broadened beyond detection. Hence, no sig-
nals of o0-H(34,44) and o0-H(38,40) for 3 have been
observed at 20 ꢀC (Fig. 2b).
2
2
observed at d 160.1 ppm [with J(F–C) = 38.6 and J(Tl–
C) = 83 Hz] and 115.7 ppm [1J(F–C) = 287.2 and 3J(Tl–
C) = 154 Hz] respectively in CD2Cl2 at ꢀ90 ꢀC [15]. These
13C resonances are also quite close to that of
Tl(tpp)(O2CCF3) in which the two corresponding carbons
2
were observed at 156.5 ppm [with J(Tl–C) = 128 Hz, and
3
2J(F–C) = 37 Hz] and 115.9 ppm [with J(Tl–C) = 239 Hz
and 1J(F–C) = 291 Hz] in THF-d8 at ꢀ100 ꢀC but with dif-
ferent 2,3J(Tl–C) coupling constants [9]. An electronegative
substituent, N(5), with a group electronegativity v = 2.98
bonded to Tl(l) in
3 and the torsion angle of
WN–C ðN–Tla–Ob–CcÞ ¼ ꢀ79:7ꢃ cause a significant negative
c
contribution up to 84 Hz for D3J(Tl–C, N) = [3J(Tl–C,
3
3) ꢀ J(Tl–C, Tl(tpp)(O2CCF3))] = 155–239 and 47 Hz
3.3. Dynamic NMR of 3 in CD2Cl2
for D2J(Tl–C, N) = [2J(Tl–C, 3) ꢀ J(Tl–C, Tl(tpp)-
2
Upon cooling of aꢀ0.02M CD2Cl2 solution of 3, the 19F
signals of CF3CO2 being a single peak at 20 ꢀC
(d = ꢀ73.50 ppm), first broadened (coalescence tempera-
ture Tc = ꢀ50 ꢀC) and then split into two peaks (d =
ꢀ72.92 ppm) with a separation of 29.4 Hz at ꢀ90 ꢀC. As
ꢀ
(O2CCF3))] = 81–128 of CF3CO2 in 3 [16–21].
To conclude, we have investigated for the first time the
three diamagnetic, mononuclear, and bridged metal com-
plexes of 21-(4-tert-butyl-benzenesulfonamido)-5,10,15,20-
t
tetraphenyl-porphyrin having M–N–(p-SO2C6H4 Bu)–N
[or M–N–tBuBS–N, M = Ga(III), Tl(III), Zn(II)] linkage,
and their X-ray structures are analyzed. The unambiguous
ꢀ
the exchange of CF3CO2 within 3 is reversible, the results
at 564.49 MHz confirm the separation as a coupling of
1
4J(Tl–F) rather than a chemical shift difference.
assignments of H NMR data for 2 and 4 in CDCl3 and 3
in CD2Cl2 are reported in this work. Dynamic 19F and 13
C
CF3
NMR spectra of the trifluoroacetato group in 3 reveal that
this group undergoes an intezrmolecular exchange with a
free energy of activation, DG223 ¼ 46:3 kJ=mol. Thus, the
tpp complexes were thoroughly studied and characterized
both by dynamic NMR and X-ray crystallography. The
correlation of D3N of the metal ion either with its ionic
CD2Cl2
-
Tl(N-p-NSO2C6H4 Bu-tpp)+
ð1Þ
t
O
CF3CO2
O
+
Tl
3
1
radius or with the H ring current effect from the protons
t
The loss of coupling is due to reversible dissociation of
of BuBS group for compounds 2, 3 and 4 is clearly
ꢀ
CF3CO2 with a small dissociation constant [14]. Such a
scenario would lead to the change in the chemicaꢀl shift with
temperature and no detectable free CF3CO2 and Tl-
explained. Mean while, the correlation of the ionic radius
of metal ion either with the dihedral angle (h) between
the bent pyrrole ring and the 3N plane or with DCb
t
t
(N-p-NSO2C6H4 Bu-tpp)+ at low temperature, but would
[=dCb (bearing a NSO2C6H4 Bu group) ꢀ dCb (without
t
lead to the loss of coupling between trifluoroacetate and
thallium at higher temperature. The chemical shift in the
high-temperature limit is the average of the two species
bearing
a
NSO2C6H4 Bu group)] is also depicted
unambiguously.
t
ꢀ
[i.e., Tl(N-p-NSO2C6H4 Bu-tpp)(O2CCF3) and CF3CO2
]
4. Supplementary material
in Eq. (1) weighted by their concentration. The free energy
of activation DGz223 ¼ 46:3 kJ=mol is therefore determined
Crystallographic data in GIF format for 2, 3 and 4 have
been deposited with Cambridge Data Centre as CCDC No.
280262 (for 2 Æ 0.5MeOH Æ 0.5H2O), CCDC No. 280263
(for 3) and CCDC No. 280264 (for 4 Æ 0.7MeOH), respec-
tively. The three solvent protons in 2 Æ 0.5MeOH Æ 0.5H2O
are not added in the file of CIF. Copies of this information
ꢀ
for the intermolecular exchange of CF3CO2 in 3.
ꢀ
At 20 ꢀC, intermolecular exchange of the CF3CO2
group is rapid as indicated by the appearance of quartet
signal due to carbonyl carbon [d 160.7, J(F–C) = 39 Hz]
2
for 3 in CD2Cl2, but no Tl–13C splitting was observed.

1872
W.-Z. Shil et al. / Polyhedron 25 (2006) 1864–1872
[7] J.P. Mahy, P. Battioni, G. Bedi, D. Mansuy, J. Fishcher, R. Weiss,
I. Morgenstern-Badarau, Inorg. Chem. 27 (1988) 353.
[8] J.E. Huheey, E.A. Keiter, R.L. Keiter, Inorganic Chemistry, 4th
ed., Harper Collins College Publishers, New York, 1993, p. 114,
292.
may be obtained free of charge from The Director, CCDC,
12 Union Road, Cambridge, CB2 1EZ, UK on request
(fax: +44 1223 336033; e-mail deposit@ccdc.cam.ac.uk or
www: http://www.ccdc.cam.ac.uk).
[9] L.F. Chou, J.H. Chen, J. Chem. Soc., Dalton Trans. (1996) 3787.
[10] A.W. Addison, T.N. Rao, J. Reedijk, J.V. Rijn, G.C. Verchoor, J.
Chem. Soc., Dalton Trans. (1984) 1349.
Acknowledgement
[11] R.G. Garvey, R.O. Koob, M.L. Morris, Acta Crystallogr., Sect. C 43
(1987) 2056.
[12] G. Murphy, P. Nogle, B. Murphy, B. Hathaway, J. Chem. Soc.,
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[13] R.S. Drago, Physical Methods for Chemists, 2nd ed., Saunder College
Publishing, New York, 1992, p. 291.
Financial support from the National Research Council
of the R.O.C. under Grant NSC 93-2113-M-005-015 is
gratefully acknowledged.
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