Synthesis and characterization of meso-ferrocenylethynyl 5,15-diphenylporphyrins

Article abstract of DOI:10.1016/j.jorganchem.2004.02.007

A series of four meso-ferrocenylethynyl (5,15-diphenylporphyrinato) nickel(II) derivatives have been synthesized by Sonogashira coupling reactions. Three of these compounds contain the electron-withdrawing groups including -CHO, -CH=C(CN)₂, and -C=CC₆H₄NO₂ at the remaining meso position, with a view to preparing push-pull chromophores, in which ferrocene serves as the electron donor. All the new compounds have been characterized spectroscopically and the molecular structure of one of these porphyrins (compound 11) has also been determined. The studies show that although the ferrocenylethynyl group can extend the π system of the central porphyrin core, the cyclopentadienyl rings of ferrocene are almost orthogonal to the porphyrin ring. This hinders ferrocene serving as a good electron donor in these systems.

Full text of DOI:10.1016/j.jorganchem.2004.02.007

Journal of Organometallic Chemistry 689 (2004) 1593–1598
www.elsevier.com/locate/jorganchem
Synthesis and characterization of meso-ferrocenylethynyl
5,15-diphenylporphyrins
*
Ka-Lok Cheng, Hung-Wing Li, Dennis K. P. Ng
Department of Chemistry, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong, China
Received 10 January 2004; accepted 10 February 2004
Abstract
A series of four meso-ferrocenylethynyl (5,15-diphenylporphyrinato)nickel(II) derivatives have been synthesized by Sonogashira
coupling reactions. Three of these compounds contain the electron-withdrawing groups including –CHO, –CH@C(CN)2, and
–CBCC6H4NO2 at the remaining meso position, with a view to preparing push–pull chromophores, in which ferrocene serves as the
electron donor. All the new compounds have been characterized spectroscopically and the molecular structure of one of these
porphyrins (compound 11) has also been determined. The studies show that although the ferrocenylethynyl group can extend the p
system of the central porphyrin core, the cyclopentadienyl rings of ferrocene are almost orthogonal to the porphyrin ring. This
hinders ferrocene serving as a good electron donor in these systems.
Ó 2004 Elsevier B.V. All rights reserved.
Keywords: Porphyrin; Ferrocene; Push–pull; Non-linear optics
1. Introduction
from the architectural flexibility, this class of functional
dyes is also thermally stable in general and can be fab-
ricated readily. To date, a substantial number of por-
phyrin-based NLO chromophores have been reported,
focusing on their third-order NLO response [4]. Push–
pull porphyrins showing second-order NLO effects are
relatively rare [5]. We have recently reported the syn-
thesis and NLO properties of a series of push–pull 5,15-
There has been a considerable interest in ‘‘push–pull’’
type chromophores with high dipole moment and mo-
lecular non-linearity [1]. These compounds are potential
electro-optic materials for applications in high-speed
photonic devices for communication, information stor-
age, and optical switching [2]. Different kinds of electron
donors, electron acceptors, and conjugated bridges have
been employed to construct a wide range of second-or-
der non-linear optical (NLO) chromophores. Detailed
theoretical studies have also been performed to elucidate
the structural control of the molecular first hyperpo-
larizability [3]. Among the various conjugated linkers,
porphyrins are of particular interest. The macrocycles,
which contain a large polarizable p-conjugated system,
constitute a two-dimensional platform for electronic
communication. The optical properties can also be
tuned by changing the metal center, its oxidation state
and axial ligands, and the peripheral substituents. Apart
diphenylporphyrins
containing
electron-releasing
(–CBCC6H4NMe2) and –withdrawing groups [–CHO,
–CH@C(CN)2, –CH@C(CO2Et)2, –CH@CHCHO] in
opposite meso positions [6]. Such a molecular design
facilitates the electronic communication between the
donor and the acceptor through the porphyrin frame-
work. Since ferrocene is a well-known electron donor for
push–pull NLO chromophores [7], we like to extend the
study to meso-ferrocenylethynyl 5,15-diphenylporphy-
rins with an electron withdrawing group at the remain-
ing meso position. The preparation and spectroscopic
properties of such a series of compounds, as well as the
molecular structure of one of the ferrocenyl porphyrins,
namely [5-ferrocenylethynyl-15-(40-nitrophenylethynyl)-
10,20-diphenylporphyrinato]nickel(II) (11) are reported
herein.
* Corresponding author. Tel.: +852-2609-6375; fax: +852-2603-5057.
E-mail address: dkpn@cuhk.edu.hk (D.K.P. Ng).
0022-328X/$ - see front matter Ó 2004 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2004.02.007

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K.-L. Cheng et al. / Journal of Organometallic Chemistry 689 (2004) 1593–1598
2. Results and discussion
manner using 4-N,N-dimethylaminophenylethyne (7) as
the coupling reagent (Scheme 2). Compound 12, which
contains the presumably electron donating ferrocenyl
and N,N-dimethylamino groups, is not a push–pull
porphyrin. In attempts to convert this compound to a
push–pull counterpart, we tried to oxidize this com-
pound (at the ferrocene center) with iodine and 2,3-di-
chloro-5,6-dicyano-1,4-benzoquinone, protonate it (at
the amino group) with HCl and HClO4, and methylate it
(at the amino group) with methyl iodide. Unfortunately,
all these attempts did not give the desired push–pull
porphyrins.
The synthesis of these ferrocenyl porphyrins involved
typical Sonogashira coupling reactions, using ferro-
cenylethyne (1) as a starting material. The porphyrin
precursors 2 and 3, which could be prepared readily by
bromination of the corresponding meso-formyl or 2,2-
dicyanoethenyl derivatives [6], were treated with 1 in the
presence of Pd(PPh3)2Cl2, CuI, and triethylamine in
tetrahydrofuran (THF) to give porphyrins 4 and 5, re-
spectively, in good yield (Scheme 1). The bis(alkynyl)
analogue 11 was prepared by two sequential palladium-
catalyzed coupling reactions from dibromoporphyrin 8
(Scheme 2). As expected, the first coupling reaction us-
ing one equiv. of 4-nitrophenylethyne (6) gave both the
mono- and di-substituted products with a substantial
amount of unreacted 8, leading to a rather low yield of
the desired product 9 (32%). This compound also re-
acted with ferrocenylethyne (1) under usual conditions,
but the yield of the product 11 (36%) was substantially
lower than that for 4 (78%) and 5 (68%). The N,N-
dimethylamino analogue 12 was prepared in a similar
All the ferrocenyl porphyrins are stable and have a
good solubility in common organic solvents. Purifica-
tion of these compounds could be performed readily by
column chromatography and recrystallization. All the
new compounds were characterized with various spec-
troscopic methods. Table 1 lists the electronic absorp-
tion data of the ferrocenyl porphyrins in CH2Cl2. All of
them show typical absorptions of metalloporphyrins,
giving a strong Soret band at 434–459 nm and one to
two Q band(s) at ꢀ560–570 and 621–649 nm. These
bands are significantly red-shifted compared with those
of (5,15-diphenylporphyrinato)nickel(II) (400, 515, and
547 nm in CHCl3) [8]. The data for 4 and 5 are also red-
shifted compared with those of the non-ferrocenylethy-
nyl analogues 13 (416, 544, and 588 nm in CH2Cl2) and
14 (385, 444, and 607 nm in CH2Cl2), respectively [6].
However, the lowest-energy Q band of 4 (621 nm) and 5
(649 nm) appears at shorter wavelength compared with
that of the (4-N,N-dimethylaminophenyl)ethynyl coun-
terparts 15 (630 nm) and 16 (667 nm), respectively [6].
All these observations indicate that the ferrocenylethy-
nyl group can extend the p conjugation of the central
porphyrin core, but the extent seems to be smaller than
the (4-N,N-dimethylaminophenyl)ethynyl moiety. An-
other remarkable feature of the absorption spectra of
these ferrocenyl porphyrins is the broadening of signals,
in particular for compound 5, which may suggest a
partial mixing of the p–pꢁ transition with an intramo-
lecular charge-transfer character [5c,5e,9].
Scheme 1.
The molecular structure of porphyrin 11 was also
confirmed by X-ray diffraction analysis. The compound
crystallizes in the triclinic system with a Pꢀ1 space group
with solvated CHCl3 and water. Fig. 1 shows a perspec-
Scheme 2.

K.-L. Cheng et al. / Journal of Organometallic Chemistry 689 (2004) 1593–1598
1595
Table 1
Electronic absorption data [kmax nm (log e)] of the ferrocenyl por-
phyrins in CH2Cl2
In summary, we have employed the Sonogashira
coupling reactions to prepare a series of meso-ferro-
cenylethynyl 5,15-diphenylporphyrins. On the basis of
the absorption spectroscopic and X-ray diffraction
studies, it can be concluded that although the ferro-
cenylethynyl group can extend the p conjugation of the
porphyrin core, ferrocene itself may not function as a
good electron donor in these systems, as a result of the
virtually orthogonal arrangement of the ferrocene and
porphyrin p systems.
Compound
Soret band
Q band(s)
4
5
434 (5.46)
457 (5.49)
443 (5.49)
459 (5.36)
ꢀ570 (sh), 621 (4.64)
- - - - - - , 649 (4.78)
556 (4.33), 621 (4.71)
557 (4.36), 631 (4.87)
11
12
3. Experimental
3.1. General
Reactions were performed under an atmosphere of
nitrogen. THF and triethylamine were distilled from so-
dium benzophenone ketyl and calcium hydride, respec-
tively. Hexanes used for chromatography was distilled
from anhydrous calcium chloride. Chromatographic pu-
rifications were performed on silica gel columns
(Macherey–Nagel, 70–230 mesh) with the indicated elu-
ents. All other solvents and reagents were of reagent grade
and used as received. Alkynes 1 [11], 6 [12], and 7 [13] and
porphyrins 2 [6], 3 [6], and 8 [6,8] were prepared according
to literature procedures.
1H NMR spectra were recorded on a Bruker DPX
300 spectrometer (300 MHz) in CDCl3 solutions.
Chemical shifts were relative to internal SiMe4 (d 0). L-
SIMS mass spectra were measured on a Bruker APEX
47e FT-ICR mass spectrometer using a 3-nitrobenzyl
alcohol matrix. UV–vis absorption spectra were taken
on a CARY 5E spectrophotometer. IR spectra were
obtained on a Nicolet Magna 550 FT-IR spectrometer
as KBr pellets.
Fig. 1. Molecular structure of 11 showing the 30% probability thermal
ꢁ
ellipsoids for all non-hydrogen atoms. Selected bond lengths (A) and
angles (°) are as follows: C(4)–C(7) ¼ 1.426(12), C(7)–C(8) ¼ 1.171(11),
C(8)–C(9) ¼ 1.434(11), C(19)–C(47) ¼ 1.426(12), C(47)–C(48) ¼ 1.200
(11), C(48)–C(51) ¼ 1.413(12), C(4)–C(7)–C(8) ¼ 176.9(10), C(7)–C(8)–
C(9) ¼ 177.6(10),
C(51) ¼ 174.4(11).
C(19)–C(47)–C(48) ¼ 176.2(11),
C(47)–C(48)–
tive view of the structure of 11, highlighting some im-
portant bond lengths and bond angles. The porphyrin
core of 11 is relatively planar. The mean deviation from
ꢁ
the porphyrin C20N4 plane is 0.112 A, which is slightly
larger than that of [5,15-bis(40-fluorophenylethynyl)-
10,20-diphenylporphyrinato]zinc(II) and 5,15-bis(40-
methoxyphenylethynyl)-10,20-diphenylporphyrin (<0.05
3.2. Preparation of meso-alkynyl 5,15-diphenylporphyrins
ꢁ
A) [10], but substantially smaller than that of the formy-
lated push–pull porphyrins reported by us earlier [6]. The
dihedral angle between the porphyrin ring and the aryl
C(1)–C(6) plane is 5.6°, showing that the two p systems
adopt a nearly coplanar arrangement. The two meso-
phenyl groups, however, are tilted with respect to the
porphyrin ring by 59.2° and 70.3°. The ferrocene C(51)–
C(55) ring is almost orthogonal to porphyrin C20N4 plane
with a dihedral angle of 85.7°. The CBC bond lengths of
C(7)–C(8) and C(47)–C(48) are 1.171(11) and 1.200(11)
3.2.1. (5-Ferrocenylethynyl-15-formyl-10,20-diphenylpor-
phyrinato)nickel(II) (4)
To a mixture of porphyrin 2 (88 mg, 0.14 mmol),
ferrocenylethyne (1) (59 mg, 0.28 mmol), Pd(PPh3)2Cl2
(25 mg, 36 lmol), and CuI (3 mg, 16 lmol) in THF (10
ml) was added triethylamine (4 ml). The mixture was
stirred at room temperature for 1 h, then the volatiles
were removed in vacuo. The residue was purified by
chromatography using toluene as eluent. The green
band was collected and rotary-evaporated to give 4 as a
ꢁ
A, respectively, which are comparable with those in other
1
meso-alkynyl porphyrins [6,10]. A close examination of
the neighboring C–C bond distances shows that there is
no significant cumulenic character in the molecule. The
results suggest that ferrocene is not a good electron donor
in these molecules, probably because of the non-coplan-
arity between the cyclopentadienyl rings of ferrocene and
the porphyrin core.
green solid (83 mg, 78%). H NMR: d 11.94 (s, 1 H,
CHO), 9.68 (d, J ¼ 5:0 Hz, 2H, b-H), 9.38 (d, J ¼ 5:0
Hz, 2H, b-H), 8.72 (d, J ¼ 5:0 Hz, 2H, b-H), 8.60 (d,
J ¼ 5:0 Hz, 2H, b-H), 7.90–7.93 (m, 4H, Ph), 7.64–7.72
(m, 6H, Ph), 4.86 (t, J ¼ 1:8 Hz, 2H, Fc-H), 4.45 (t,
J ¼ 1:8 Hz, 2H, Fc-H), 4.39 (s, 5H, Fc-H). HRMS
(LSI): m=z calcd for C45H2856FeN458NiO (Mþ)

1596
K.-L. Cheng et al. / Journal of Organometallic Chemistry 689 (2004) 1593–1598
754.0966, found 754.1008. IR (KBr): 2194 w (v CBC),
1672 s (v C@O) cmꢂ1
8 was discarded. The second reddish-green band was
collected and evaporated to give 10 as a green solid (115
.
1
mg, 53%). H NMR: d 9.52 (d, J ¼ 4:8 Hz, 2H, b-H),
3.2.2. [5-(20,20-Dicyanoethenyl)-15-ferrocenylethynyl-10,
20-diphenylporphyrinato]nickel(II) (5)
9.41 (d, J ¼ 5:1 Hz, 2H, b-H), 8.67–8.71 (m, 4H, b-H),
7.95–7.98 (m, 4H, Ph), 7.77 (d, J ¼ 8:4 Hz, 2H, C6H4),
7.68–7.73 (m, 6H, Ph), 6.82 (d, J ¼ 8:4 Hz, 2H, C6H4),
3.08 (s, 6H, NMe2).
To a mixture of porphyrin 3 (58 mg, 0.09 mmol),
ferrocenylethyne (1) (36 mg, 0.17 mmol), Pd(PPh3)2Cl2
(15 mg, 21 lmol), and CuI (2 mg, 11 lmol) in THF (10
ml) was added triethylamine (4 ml). The mixture was
stirred at room temperature for 4 h, then the volatiles
were removed in vacuo. The residue was purified by
chromatography using toluene as eluent. The green
band was collected and rotary-evaporated to give 5 as a
green solid (47 mg, 68%). 1H NMR: d 9.87 (s, 1H,
CH@C), 9.33 (d, J ¼ 4:8 Hz, 2H, b-H), 9.02 (d, J ¼ 5:1
Hz, 2H, b-H), 8.69 (d, J ¼ 5:1 Hz, 2H, b-H), 8.56 (d,
J ¼ 4:8 Hz, 2H, b-H), 7.87–7.90 (m, 4H, Ph), 7.64–7.70
(m, 6H, Ph), 4.85 (t, J ¼ 1:8 Hz, 2H, Fc-H), 4.47 (t,
J ¼ 1:8 Hz, 2H, Fc-H), 4.39 (s, 5H, Fc-H). HRMS
(LSI): m=z calcd for C48H2856FeN658Ni (Mþ) 802.1078,
found 802.1063. IR (KBr): 2219 w, 2193 m (v CBC and
3.2.5. [5-Ferrocenylethynyl-15-(40-nitrophenylethynyl)-
10,20-diphenylporphyrinato]nickel(II) (11)
To a mixture of porphyrin 9 (83 mg, 0.11 mmol),
ferrocenylethyne (1) (36 mg, 0.17 mmol), Pd(PPh3)2Cl2
(6 mg, 9 lmol), and CuI (3 mg, 16 lmol) in THF (25 ml)
was added triethylamine (10 ml). The mixture was stir-
red at 60 °C for 12 h, then the volatiles were removed in
vacuo. The residue was purified by chromatography
using hexanes/CHCl3 (1:4) as eluent. The green band
was collected and rotary-evaporated to give 11 as a
1
green solid (35 mg, 36%). H NMR: d 9.48 (d, J ¼ 4:8
Hz, 2H, b-H), 9.44 (d, J ¼ 4:2 Hz, 2H, b-H), 8.72–8.75
(m, 4H, b-H), 8.38 (d, J ¼ 7:8 Hz, 2H, C6H4), 7.98–8.03
(m, 6H, Ph and C6H4), 7.71–7.73 (m, 6H, Ph), 4.87 (s,
2H, Fc-H), 4.45 (s, 2H, Fc-H), 4.39 (s, 5H, Fc-H).
HRMS (LSI): m=z calcd for C52H3156FeN558NiO2 (Mþ)
871.1180, found 871.1115. IR (KBr): 2194 m (v CBC),
CBN) cmꢂ1
.
3.2.3. [5-Bromo-15-(40-nitrophenylethynyl)-10,20-diphe-
nylporphyrinato]nickel(II) (9)
1508 m (vasy NO2), 1331 s (vsym NO2) cmꢂ1
.
Dibromoporphyrin 8 (400 mg, 0.59 mmol), 4-nitro-
phenylethyne (6) (130 mg, 0.88 mmol), Pd(PPh3)2Cl2
(33 mg, 47 lmol), and CuI (13 mg, 68 lmol) were
dissolved in THF (40 ml). Triethylamine (15 ml) was
then added dropwise into the mixture, which was then
stirred at 60 °C for 12 h. After removing the volatiles
in vacuo, the residue was chromatographed using tol-
uene/hexanes (1:1) as eluent. The first red band, which
contained a trace amount of unreacted porphyrin 8
was discarded. The second reddish-green band was
collected and evaporated to give 9 as a green solid (141
3.2.6. [5-Ferrocenylethynyl-15-(40-N,N-dimethylamino-
phenylethynyl)-10,20-diphenylporphyrinato]nickel(II)
(12)
To a mixture of porphyrin 10 (100 mg, 0.14 mmol),
ferrocenylethyne (1) (57 mg, 0.27 mmol), Pd(PPh3)2Cl2
(24 mg, 34 lmol), and CuI (3 mg, 16 lmol) in THF (10
ml) was added triethylamine (4 ml). The mixture was
stirred at 60 °C for 12 h, then the volatiles were removed
in vacuo. The residue was purified by chromatography
using hexanes/CHCl3 (1:4) as eluent. The green band
was collected and rotary-evaporated to give 12 as a
1
mg, 32%). H NMR: d 9.52 (br. s, 2H, b-H), 8.80–8.85
(m, 4H, b-H), 8.37 (d, J ¼ 7:8 Hz, 2H, C6H4), 7.97–
8.02 (m, 6H, Ph and b-H or C6H4), 7.61–7.79 (m, 8H,
Ph and b-H or C6H4). UV–vis (CH2Cl2) [kmax nm
ðlog eÞ]: 435 (5.10), 543 (4.08), 581 (4.13). IR (KBr):
2191 w (v CBC), 1511 m (vasy NO2), 1333 s (vsym NO2),
1
green solid (53 mg, 45%). H NMR: d 9.50 (d, J ¼ 4:8
Hz, 2H, b-H), 9.45 (d, J ¼ 4:8 Hz, 2H, b-H), 8.70 (d,
J ¼ 5:1 Hz, 2H, b-H), 8.68 (d, J ¼ 5:1 Hz, 2H, b-H),
7.97–8.00 (m, 4H, Ph), 7.67–7.76 (m, 8H, Ph and C6H4),
6.76 (d, J ¼ 8:4 Hz, 2H, C6H4), 4.86 (s, 2H, Fc-H), 4.41
(s, 7H, Fc-H). HRMS (LSI): m=z calcd for
C54H3756FeN558Ni (Mþ) 869.1752, found 869.1765. IR
849 m (v C–N) cmꢂ1
.
3.2.4. [5-Bromo-15-(40-N,N-dimethylaminophenylethy-
nyl)-10,20-diphenylporphyrinato]nickel(II) (10)
(KBr): 2178 m (v CBC) cmꢂ1
.
Dibromoporphyrin 8 (200 mg, 0.30 mmol), 4-N,N-
dimethylaminophenylethyne (7) (78 mg, 0.54 mmol),
Pd(PPh3)2Cl2 (17 mg, 24 lmol), and CuI (8 mg, 42
lmol) were dissolved in THF (25 ml). Triethylamine (10
ml) was then added dropwise into the mixture, which
was then stirred at 50 °C for 12 h. After removing the
volatiles in vacuo, the residue was chromatographed
using toluene/hexanes (1:1) as eluent. The first red band,
which contained a trace amount of unreacted porphyrin
3.3. X-ray crystallographic analysis of 11 ꢃ CHCl3 ꢃ
1.5H2O
Crystal data and details of data collection and
structure refinement are given in Table 2. Data were
collected on a Bruker SMART CCD diffractometer with
ꢁ
an Mo Ka sealed tube (k ¼ 0:71073 A) at 293 K, using a
x scan mode with an increment of 0.3 °. Preliminary unit

K.-L. Cheng et al. / Journal of Organometallic Chemistry 689 (2004) 1593–1598
1597
Table 2
Crystallographic data for 11 ꢃ CHCl3 ꢃ 1.5H2O
(c) S. Liu, M.A. Haller, H. Ma, L.R. Dalton, S.-H. Jang, A.K.-Y.
Jen, Adv. Mater. 15 (2003) 603–607;
(d) A.M. Kelley, W. Leng, M. Blanchard-Desce, J. Am. Chem.
Soc. 125 (2003) 10520–10521;
11 ꢃ CHCl3 ꢃ 1.5H2O
C53H35Cl3FeN5NiO3:5
Formula
ꢂ
(e) R. Andreu, J. Garın, J. Orduna, R. Alcala, B. Villacampa,
Org. Lett. 5 (2003) 3143–3146.
ꢂ
Formula weight
Crystal size (mm3)
Crystal system
Space group
1018.77
0.53 ꢄ 0.29 ꢄ 0.20
Triclinic
[2] (a) L.R. Dalton, W.H. Steier, B.H. Robinson, C. Zhang, A. Ren,
S. Garner, A. Chen, T. Londergan, L. Irwin, B. Carlson, L.
Fifield, G. Phelan, C. Kincaid, J. Amend, A. Jen, J. Mater. Chem.
9 (1999) 1905–1920;
P1ꢀ
ꢁ
a (A)
11.2859 (10)
14.6870 (13)
15.2904 (13)
108.344 (2)
90.698 (2)
106.768 (2)
2288.6 (3)
2
ꢁ
b (A)
(b) M. Lee, H.E. Katz, C. Erben, D.M. Gill, P. Gopalan, J.D.
Heber, D.J. McGee, Science 298 (2002) 1401–1403;
(c) S.K. Park, J.Y. Do, J.-J. Ju, S. Park, M.-S. Kim, M.-H. Lee,
Macromol. Rapid Commun. 24 (2003) 772–777.
ꢁ
c (A)
a (°)
b (°)
c (°)
[3] (a) S.R. Marder, J.W. Perry, Adv. Mater. 5 (1993) 804–815;
(b) J. Abe, Y. Shirai, J. Am. Chem. Soc. 118 (1996) 4705–4706;
(c) I.D.L. Albert, T.J. Marks, M.A. Ratner, Chem. Mater. 10
(1998) 753–762;
3
ꢁ
V (A )
Z
F (0 0 0)
1042
1.478
Dcalcd (mg mꢂ3
)
ꢂ
(d) M.C.R. Delgado, V. Hernandez, J. Casado, J.T.L. Navarrete,
l (mmꢂ1
h range (°)
)
0.956
1.41–24.00
11791
J.-M. Raimundo, P. Blanchard, J. Roncali, Chem. Eur. J. 9 (2003)
3670–3682;
Total number of reflections
Number of independent reflections
Number of parameters
R1½I > 2rðIÞꢅ
ꢃ
(e) S. Di Bella, I. Fragala, Eur. J. Inorg. Chem. (2003) 2606–2611;
7132 ðRint ¼ 0:0497Þ
597
0.0788
(f) R.J. Sa, K.C. Wu, C.S. Lin, P. Liu, C.Y. Mang, Chin. J. Chem.
21 (2003) 377–381;
(g) A.D. Tillekaratne, R.M. de Silva, K.M.N. de Silva, J. Mol.
Struct. Theochem 638 (2003) 169–176.
wR2½I > 2rðIÞꢅ
0.2148
0.963
Goodness of fit
[4] (a) See for example: M. Ravikanth, G.R. Kumar, Curr. Sci. 68
(1995) 1010–1017;
(b) K. Kandasamy, S.J. Shetty, P.N. Puntambekar, T.S. Srivast-
ava, T. Kundu, B.P. Singh, Chem. Commun. (1997) 1159–
1160;
cell parameters were obtained from 45 frames. Final unit
cell parameters were derived by global refinements of
reflections obtained from integration of all the frame
data. The collected frames were integrated by using the
preliminary cell-orientation matrix. SMART software
was used for collecting frames of data, indexing reflec-
tions, and determination of lattice constants; SAINT-
PLUS for integration of intensity of reflections and
scaling [14]; SADABS for absorption correction [15]; and
SHELXL for space group and structure determination,
refinements, graphics, and structure reporting [16].
Crystallographic data (excluding structure factors) for
this structure have been deposited with the Cambridge
Crystallographic Data Centre as supplementary publi-
cation no. CCDC-224460. Copies of the data can be
obtained, free of charge, on application to CCDC, 12
Union Road, Cambridge CB2 1EZ, UK (fax: +44-1223-
336033 or e-mail: deposit@ccdc.cam.ac.uk).
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This work was supported by The Chinese University
of Hong Kong (Direct Grant 1999-2000, Project Code
2060173).
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