Synthesis and structural characterization of a photoresponsive organodirhodium complex with active S-S bonds: [(CpPhRh)2(μ-CH2)2(μ-O2SSO2)] (CpPh = η5-C5Me4Ph)

Article abstract of DOI:10.1016/j.jorganchem.2006.08.063

A photoresponsive rhodium dinuclear complex having phenyltetramethylcyclopentadienyl (Cp^Ph = η⁵-C₅Me₄Ph) and photosensitive dithionite (μ-O₂SSO₂) ligands, [(Cp^PhRh)₂(μ-CH₂)₂(μ-O₂SSO₂)] (1), has been synthesized. The crystal of complex 1 (monoclinic, C2/m (No. 12), a = 24.805(2) A?, b = 29.111(2) A?, c = 10.8475(11) A?, β = 105.9830(7)°, V = 7530.0(12) A?³, Z = 8) consists of two independent molecules, 1-cis and 1-trans, with different arrangement of the Cp^Ph ligands. The flexibility, volume, and shape of the reaction cavities around the dithionite unit of 1-cis and 1-trans in the crystal are discussed. The crystal structures of the precursors of 1, trans-[(Cp^PhRh)₂(μ-Cl)₂Cl₂] and trans-[(Cp^PhRh)₂(μ-CH₂)₂Me₂], are also reported.

Full text of DOI:10.1016/j.jorganchem.2006.08.063

Journal of Organometallic Chemistry 692 (2007) 122–128
www.elsevier.com/locate/jorganchem
Synthesis and structural characterization of a photoresponsive
organodirhodium complex with active S–S bonds:
[(CpPhRh)2(l-CH2)2(l-O2SSO2)] (CpPh = g5-C5Me4Ph)
*
*
Yousuke Miyano, Hidetaka Nakai , Yoshihito Hayashi, Kiyoshi Isobe
Department of Chemistry, Graduate School of Natural Science and Technology, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan
Received 28 February 2006; accepted 3 April 2006
Available online 30 August 2006
Abstract
A photoresponsive rhodium dinuclear complex having phenyltetramethylcyclopentadienyl (CpPh = g5-C5Me4Ph) and photosensitive
dithionite (l-O2SSO2) ligands, [(CpPhRh)2(l-CH2)2(l-O2SSO2)] (1), has been synthesized. The crystal of complex 1 (monoclinic, C2/m
3
˚
˚
˚
˚
(No. 12), a = 24.805(2) A, b = 29.111(2) A, c = 10.8475(11) A, b = 105.9830(7)ꢀ, V = 7530.0(12) A , Z = 8) consists of two independent
molecules, 1-cis and 1-trans, with different arrangement of the CpPh ligands. The flexibility, volume, and shape of the reaction cavities
around the dithionite unit of 1-cis and 1-trans in the crystal are discussed. The crystal structures of the precursors of 1, trans-
[(CpPhRh)2(l-Cl)2Cl2] and trans-[(CpPhRh)2(l-CH2)2Me2], are also reported.
ꢁ 2006 Elsevier B.V. All rights reserved.
Keywords: Dithionite complex; Crystal structure; Photochromism
1. Introduction
(l-OSOSO2)] proceeds in the reaction cavities formed by
the Cp* ligands in the crystal. We speculate that the key
feature allowing the reversible crystalline-state reaction in
this system is the flexibility of the reaction cavity. In order
to find a role of the reaction cavity in reversible crystalline-
state reactions, we are currently preparing various deriva-
tives of dithionite complexes by chemical modification of
the Cp* ligands of [(Cp*Rh)2(l-CH2)2(l-O2SSO2)]. Herein,
we report the synthesis and structural characterization of a
new dithionite complex with phenyltetramethylcyclopenta-
Photochromic compounds, which show reversible crys-
talline-state reactions, have attracted remarkable attention
because of their potential applications for optical memory
media and optical switching devices [1–3]. Although a great
number of photochromic compounds have been reported,
little is known about compounds having photochromic
reactivity in the crystalline-state. We have recently found
that a new class of photochromic compound, rhodium
dinuclear complex with two Cp* (= g5-C5Me5) and photo-
reactive dithionite (l-O2SSO2) ligands [(Cp*Rh)2(l-CH2)2-
(l-O2SSO2)], shows intriguing photochromic performance,
such as reversible 100% photo- and thermo-chemical con-
versions in the crystalline-state (Scheme 1) [4].
dienyl ligands, [(CpPhRh)2(l-CH2)2(l-O2SSO2)] (CpPh
=
g5-C5Me4Ph) (1) (Scheme 2), together with the crystal
structures of its precursors, trans-[(CpPhRh)2(l-Cl)2Cl2]
(RhClCl) and trans-[(CpPhRh)2(l-CH2)2Me2] (RhCH2Me).
This reversible oxygen transfer reaction between
[(Cp*Rh)2(l-CH2)2(l-O2SSO2)] and [(Cp*Rh)2(l-CH2)2-
2. Results and discussion
The synthesis of the dithionite complex 1 is summa-
rized in Scheme 2. The solid-state molecular structures
of RhClCl, RhCH2Me, and 1 were determined by X-ray
*
Corresponding authors. Fax: +81 76 264 5742.
E-mail address: isobe@cacheibm.s.kanazawa-u.ac.jp (K. Isobe).
0022-328X/$ - see front matter ꢁ 2006 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2006.08.063

Y. Miyano et al. / Journal of Organometallic Chemistry 692 (2007) 122–128
123
diffraction analysis and are shown in Figs. 1 and 2. Crys-
tal data are summarized in Table 1 and selected bond
lengths and angles are listed in Table 2.
Although the synthesis of the dichloro–dimer complex,
RhClCl, was reported in 2005 [5], this complex has not been
structurally characterized. Recrystallization of RhClCl from
CH2Cl2/AcOEt at room temperature yields single crystals
suitable for X-ray diffraction analysis. Fig. 1 (left) show
the molecular structure of RhClCl. The bond distance and
Scheme 1. Crystalline-state photochromism.
Scheme 2. Synthesis of dithionite complex 1.
Fig. 1. Solid-state molecular structures of RhClCl (left) and RhCH2Me (right). Hydrogen atoms are omitted for clarity, thermal ellipsoids are at 50%
probability.

124
Y. Miyano et al. / Journal of Organometallic Chemistry 692 (2007) 122–128
Fig. 2. Solid-state molecular structures of 1-cis (left) and 1-trans (right) in crystals of 1 Æ 0.5CH2Cl2 Æ C7H8. Hydrogen atoms and co-crystallized solvent
molecules are omitted for clarity, thermal ellipsoids are at 50% probability.
Table 1
Crystallographic data for RhClCl, RhCH2Me, and 1
RhClCl
RhCH2Me
1 Æ 0.5CH2Cl2 Æ C7H8
Formula
Fw
C30H34Cl4Rh2
742.22
C34H44Rh2
658.53
C39.5H38ClO4Rh2S2
882.12
Crystal system
Space group
Monoclinic
P21/c (No. 14)
12.4756(7)
15.7361(8)
14.7026(8)
90
91.9430(5)
90
2884.7(3)
4
Monoclinic
P21/n (No. 14)
10.299(1)
11.508(1)
12.267(2)
90
99.0088(9)
90
1435.9(3)
2
Monoclinic
C2/m (No. 12)
24.805(2)
29.111(2)
10.8475(11)
90
105.9830(7)
90
7530.0(12)
8
˚
a (A)
˚
b (A)
˚
c (A)
a (ꢀ)
b (ꢀ)
c (ꢀ)
3
˚
V (A )
Z
l (cmÀ1
F(000)
)
15.30
1488
1.709
11.67
676
1.523
10.95
3568
1.556
Dcalc (g/cm3)
Temperature (K)
Reflections collected
Independent reflections
Data/parameters
R1 [I > 2r(I)]
173
31969
31042 (Rint = 0.019)
6551/326
0.026
173
15987
3278 (Rint = 0.026)
3278/164
0.029
123
41903
8738 (Rint = 0.045)
8738/472
0.057
wR2 (all data)
0.069
0.075
0.123
Goodness-of-fit
1.053
1.078
1.155
angles of the Rh2(l-Cl)2Cl2 unit in RhClCl compare well to
those found for the corresponding Cp* analogue trans-
[(Cp*Rh)2(l-Cl)2Cl2] [6]. The average Rh–Cl(terminal):
trans-Rh2(l-CH)2Me2 core unit can be unequivocally
determined by X-ray diffraction technique (Fig. 1 (right)).
Although the trans- and cis-isomer of the Cp* analogue
[(Cp*Rh)2(l-CH2)2Me2] are known, only the cis-isomer,
cis-[(Cp*Rh)2(l-CH2)2Me2], has been structurally charac-
terized so far. The dimetallacyclobutane (Rh2C2) ring in
the trans-isomer, RhCH2Me, is planar while that in cis-
[(Cp*Rh)2(l-CH2)2Me2] is puckered (angle of fold, 28ꢀ
about Rh–Rh). The Rh–C(terminal) and average Rh–
C(bridging) distances in RhCH2Me are 2.075(3) and
˚
˚
2.3813(6) A and Rh–Cl(bridging): 2.4460(6) A distances in
RhClCl are slightly shorter than those of the Cp* analogue
˚
(Rh–Cl(terminal): 2.3967(11) A and Rh–Cl(bridging):
˚
2.4586(11) A). The Rh–Cl(bridging)–Rh and Cl(bridging)–
Rh–Cl(bridging) angles in RhClCl are 3.6ꢀ more acute and
obtuse, respectively, than those of the Cp* analogue. Thus,
these results suggest that the electronic structure of the core
unit in this system can be controlled by changing the ligand
˚
2.019(3) A, respectively. The Rh–C(bridging)–Rh and
from Cp* to CpPh
.
C(bridging)–Rh–C(bridging) angles in RhCH2Me are
The methylene–methyl complex, RhCH2Me, can be syn-
thesized by modifying the procedure for the corresponding
Cp* analogue trans-[(Cp*Rh)2(l-CH2)2Me2] [7]. Addition-
ally, the molecular structure of RhCH2Me having the
81.0(1) and 99.0(1)ꢀ, respectively.
Treatment of the methylene–methyl complex, RhCH2Me
,
with acetylchloride in CH2Cl2 yields the methylene–chloro
complex, RhCH2Cl, as a red–brown powder (87%). This

Y. Miyano et al. / Journal of Organometallic Chemistry 692 (2007) 122–128
125
Table 2
Selected bond lengths (A) and angles (ꢀ) for RhClCl, RhCH2Me, and 1
formation of the dithionite complex, 1, in good yield
(62%) as a brown powder. Crystals of 1 suitable for X-
ray diffraction analysis were grown from CH2Cl2/toluene
(C7H8) in the dark at room temperature. The crystal of
complex 1 consists of two independent dithionite com-
plexes, 1-cis and 1-trans (Fig. 2) [8], one dichloromethane
molecule, and three independent toluene molecules. One
of three toluene molecules is ordered. Other two toluene
molecules are disordered in the same fashion (a disorder
model for these toluene molecules is shown in inset of
Fig. 3). There are a 1/2 of 1-cis, a 1/2 of 1-trans, a 1/2 of
CH2Cl2, a 1/2 of C7H8, and two 1/4 of C7H8 in an asym-
metric unit (1 Æ 0.5CH2Cl2 Æ C7H8).
˚
RhClCl
RhCH2Me
1-cis
2.6334(4)
1-trans
Rh–Rh
Rh–Cl(terminal)
3.5980(2)
2.3785(6)
2.3840(6)
2.3813(6)
2.6224(3)
2.6285(4)
Average
Rh–Cl(bridging)
2.4506(6)
2.4447(5)
2.4366(5)
2.4522(6)
2.4460(6)
Average
Rh–C(terminal)
Rh–C(bridging)
2.075(3)
2.017(3)
2.020(3)
2.019(3)
2.050(5)
2.051(5)
2.051(5)
2.054(5)
2.043(4)
2.049(5)
The solid-state molecular structures of the two indepen-
dent dithionite complexes, 1-cis and 1-trans, in crystals of
1 Æ 0.5CH2Cl2 Æ C7H8 are depicted in Fig. 2.
Average
Rh–S
S–S
S–O
2.284(1)
2.295(2)
1.469(4)
1.456(4)
1.463(4)
2.283(1)
2.299(2)
1.449(4)
1.458(4)
1.454(4)
The molecule of 1-cis has a mirror plane through two
bridged methylene carbons and a center of the Rh–Rh
bond. The phenyl rings of the CpPh ligands of 1-cis are
arranged in a cis fashion to the Rh–Rh bond. The other
molecule, 1-trans, has a C2 axis bisecting the Rh–Rh and
S–S bonds. The phenyl rings in 1-trans are arranged in a
trans fashion to the Rh–Rh bond. Except for the arrange-
ment of the CpPh ligands, the solid-state structure of the
Rh2(l-CH2)2(l-O2SSO2) core fragment of 1-cis is compara-
ble to that found for 1-trans. For instance, the Rh–Rh
bond distances in 1-cis and 1-trans are 2.6334(4) and
Average
Rh–Cl–Rh
94.82(2)
94.57(2)
94.70(2)
Average
Rh–C–Rh
81.0(1)
99.0(1)
79.9(2)
79.9(2)
79.9(2)
79.8(2)
99.9(2)
Average
Cl–Rh–Cl
85.23(2)
85.37(2)
85.30(2)
˚
2.6285(4) A, respectively. The bond lengths and angles of
Average
C–Rh–C
the Rh2(l-CH2)2(l-O2SSO2) core fragments of 1-cis and
1-trans are also similar to that found for the Cp* analogue
[(Cp*Rh)2(l-CH2)2(l-O2SSO2)] [4]. The S–S bond distances
99.9(2)
powder is contaminated with a very small amount of RhClCl
as a by-product; however, this material is enough purity for
further reaction.
in 1-cis (2.295(2) A) and 1-trans (2.299(2) A), however, are
˚
˚
clearly shorter than that in the Cp* analogue (2.330(2) A).
˚
This implies that the dithionite ligand in 1 has an electronic
structure and photo-reactivity different from that in the
Cp* analogue.
The reaction of the methylene–chloro complex, RhCH2Cl
,
with Na2S2O4 in MeOH under N2 in the dark led to the
Fig. 3. The CpPh ligands and solvent molecules around the dithionite unit of 1-cis viewed from front (left) and side (right) of 1-cis. Disorder model for a
toluene molecule (inset).

126
Y. Miyano et al. / Journal of Organometallic Chemistry 692 (2007) 122–128
It is worthwhile to note that the reaction cavities for the
Our preliminary experiment shows that new dithionite
complex 1 has photochromic reactivity in the crystalline-
state. We are currently investigating the correlation
between the reaction cavities (flexibility, volume, and
shape) and photochromic performance using the crystal
of 1 Æ 0.5CH2Cl2 Æ C7H8 containing the two kinds of reac-
tion cavity as mentioned above.
ditionite unit of 1-cis and 1-trans in the crystal have quite
different character. The dithionite unit of 1-cis is sur-
rounded by rigid CpPh ligands of neighboring complexes
and flexible co-crystalized solvents (dichloromethane and
disorderd toleune) (Fig. 3). In contrast, the dithionite unit
of 1-trans is only surrounded by rigid CpPh ligands of
neighboring complexes (Fig. 4). Consequently, 1-cis has a
more flexible reaction cavity than 1-trans does.
3. Experimental
There is some approach to explain the reactivity in the
solid state [9,10]: the volume and shape of the void space
around the reaction group (= reaction cavity) in the crystal
are very informative in estimating the reactivity. The reac-
tion cavities for the dithionite unit of 1-cis and 1-trans were
calculated by using Cavity 5.0 [11]. Figs. 5 and 6 illustrate
the cavities of 1-cis and 1-trans.
3.1. General
All experiments were performed under a dry nitrogen
atmosphere using standard Schlenk techniques. Solvents
used were purified by distillation before use. Rhodium(III)
chloride trihydrate, RhCl3 Æ 3H2O, was purchased from
Tanaka Kikinzoku Kogyo K.K. Sodium dithionite,
Na2S2O4, was purchased from Aldrich. All other chemicals
were obtained from commercial sources and used as
received unless otherwise noted. The phenyl derivative
ligand, HCpPh = HC5Me4Ph, was synthesized by the litera-
ture procedures [12]. 1H and 13C NMR spectra were
recorded on a JEOL Lambda 400 FT-NMR spectrometer
The cavities in 1-cis and 1-trans have the volume of 7.34
3
˚
and 9.45 A , respectively. Thus, the features of the reaction
cavities of 1-cis and 1-trans in the crystal of
1 Æ 0.5CH2Cl2 Æ C7H8 are summarized as follows:
Flexibility: 1-cis > 1-trans
Volume: 1-cis < 1-trans
Fig. 4. The CpPh ligands and phenyl moieties of CpPh ligand around the dithionite unit of 1-trans viewed from front (left) and side (right) of 1-trans.
˚
Fig. 5. Front (left) and bottom (right) views of the reaction cavity for the dithionite unit of 1-cis. The contours are drawn in sections separated by 0.10 A.

Y. Miyano et al. / Journal of Organometallic Chemistry 692 (2007) 122–128
127
Fig. 6. Front (left) and bottom (right) views of the reaction cavity for the dithionite unit of 1-trans. The contours are drawn in sections separated by
˚
0.10 A.
in CDCl3. Chemical shifts were referenced to protio solvent
impurities (1H: d 7.26, 13C: d 77.0 (CDCl3)) and are
reported in ppm. Elemental analyses were performed by
the Advanced Science Research Center at Kanazawa Uni-
versity on a Yanaco MT-5 CHN autocorder.
538 mg, 59%. Single crystals suitable for X-ray diffraction
analysis were obtained by diffusion of MeOH into a solu-
tion of RhCH2Me in CH2Cl2 at room temperature.
1H NMR (400 MHz, CDCl3): d 8.36 (4H, t, l-CH2), 7.30–
7.37 (4H, m, C5Me4Ph), 7.19–7.28 (6H, m, C5Me4Ph), 1.78
(12H, s, C5Me4Ph), 1.62 (12H, s, C5Me4Ph), À0.78 (6H, s,
CH3). 13C NMR(100 MHz, CDCl3): d 164.0 (l-CH2),
134.9 (C5Me4Ph), 131.7 (C5Me4Ph), 127.8 (C5Me4Ph),
126.1 (C5Me4Ph), 103.3 (C5Me4Ph), 103.2 (C5Me4Ph),
101.4 (C5Me4Ph), 10.3 (C5Me4Ph), 10.0 (C5Me4Ph), À3.0
(CH3). Anal. Calc. for [(CpPhRh)2(l-CH2)2(CH3)2]: C,
62.01; H, 6.73. Found: C, 61.85; H, 6.84%.
3.2. Synthesis of trans-[(CpPhRh)2(l-Cl)2Cl2] (RhClCl
)
A mixture of RhCl3 Æ 3H2O (3.60 g, 13.7 mmol) and
HCpPh (4.08 g, 20.6 mmol) in MeOH (30 ml) was refluxed
for 24 h under N2. After the reaction mixture was cooled
to room temperature, the resulting red precipitate was fil-
tered and washed with Et2O. Yield 3.97 g, 78%. Single crys-
tals suitable for X-ray diffraction analysis were obtained by
diffusion of AcOEt into a solution of RhClCl in CH2Cl2 at
room temperature.
3.4. Synthesis of trans-[(CpPhRh)2(l-CH2)2Cl2]
(RhCH2Cl
)
1H NMR (400 MHz, CDCl3): d 7.61–7.68 (4H, m,
C5Me4Ph), 7.33–7.41 (6H, m, C5Me4Ph), 1.71 (12H, s,
C5Me4Ph), 1.67 (12H, s, C5Me4Ph). 13C NMR (100
MHz, CDCl3): d 130.2 (C5Me4Ph), 128.9 (C5Me4Ph),
128.6 (C5Me4Ph), 128.3 (C5Me4Ph), 100.3 (C5Me4Ph),
100.2 (C5Me4Ph), 93.5 (C5Me4Ph), 93.4 (C5Me4Ph),
90.6 (C5Me4Ph), 90.5 (C5Me4Ph), 10.6 (C5Me4Ph), 9.6
(C5Me4Ph). Anal. Calc. for [(CpPhRh)2(l-Cl)2Cl2]: C,
48.55; H, 4.62. Found: C, 48.18; H, 4.65%.
Acetylchloride (0.26 ml, 1.80 mmol) was added to a
solution of RhCH2Me (410 mg, 0.62 mmol) in CH2Cl2
(20 ml) at 0 ꢀC. The reaction mixture was stirred for
30 min at 0 ꢀC, allowed to warm up to room temperature,
and then refluxed for 12 h. MeOH (10 ml) was added to the
solution and the solvent was removed in vacuo. The red–
brown solid was extracted with toluene (50 ml). The extract
was concentrated and washed with Et2O (10 ml) to give
RhCH2Cl as a red–brown solid. Yield 380 mg, 87%.
1H NMR (400 MHz, CDCl3): d 10.55 (4H, t, l-CH2),
7.20–7.46 (10H, m, C5Me4Ph), 1.79 (12H, s, C5Me4Ph),
1.52 (12H, s, C5Me4Ph). 13C NMR (100 MHz, CDCl3):
d 187.7 (l-CH2), 132.0 (C5Me4Ph), 131.0 (C5Me4Ph),
128.1 (C5Me4Ph), 127.5 (C5Me4Ph), 109.7 (C5Me4Ph),
102.5 (C5Me4Ph), 100.9 (C5Me4Ph), 10.6 (C5Me4Ph), 10.0
(C5Me4Ph).
3.3. Synthesis of trans-[(CpPhRh)2(l-CH2)2Me2]
(RhCH2Me
)
An 1.03 M solution of AlMe3 in hexane (4.5 ml,
4.64 mmol) was added dropwise to a stirred suspension
of RhClCl (1.02 g, 1.38 mmol) in toluene (30 ml) at
À40 ꢀC. After stirring for 1 h at À40 ꢀC, the resulting solu-
tion was allowed to warm up to room temperature. Ace-
tone (4.5 ml) was slowly added and stirred for 12 h at
room temperature. MeOH (30 ml) was added to the solu-
tion and the solvent was removed in vacuo. The red solid
was washed with pentane (100 ml) and extracted with
CH2Cl2 (100 ml). The extract was concentrated and washed
with MeOH (50 ml) to give RhCH2Me as a red solid. Yield
3.5. Synthesis of [(CpPhRh)2(l-CH2)2(l-O2SSO2)] (1)
A mixture of RhCH2Cl (200 mg, 0.29 mmol) and Na2S2O4
(68 mg, 0.39 mmol) in MeOH (30 ml) was stirred for 6 h
under N2 in the dark at room temperature. The solvent
was removed under reduced pressure to give a reddish
brown solid. The crude product was dissolved in 20 ml of

128
Y. Miyano et al. / Journal of Organometallic Chemistry 692 (2007) 122–128
CH2Cl2 and the insoluble solid was filtered off. Removal of
the solvent gave 1 as a brown solid. This solid was washed
with toluene and Et2O. Yield 134 mg, 62%. Single crystals
suitable for X-ray diffraction analysis were obtained by dif-
fusion of toluene (C7H8) into a solution of 1 in CH2Cl2 at
room temperature.
Center (CCDC). CCDC reference number: 299813
(RhClCl), 299814 (RhCH2Me), and 282559 (1).
Acknowledgements
The present work was financially supported by the
Grant-in-Aid for Scientific Research (KAKENHI) in Pri-
ority Area ‘‘Dynamic Complex’’, ‘‘Molecular Nano
Dynamics’’, and ‘‘Chemistry of Coordination Space’’ from
Ministry of Education, Culture, Sports, Science and Tech-
nology and Tokuyama Science Foundation.
1H NMR (400 MHz, CDCl3): d 9.71 (2H, s, l-CH2),
8.76 (2H, t, l-CH2), 7.31–7.51 (10H, m, C5Me4Ph), 1.86
(12H, s, C5Me4Ph), 1.76 (12H, s, C5Me4Ph). 13C NMR
(100 MHz, CDCl3): d 175.6 (l-CH2), 131.0 (C5Me4Ph),
130.3 (C5Me4Ph), 128.5 (C5Me4Ph), 128.3 (C5Me4Ph),
108.7 (C5Me4Ph), 107.3 (C5Me4Ph), 103.6 (C5Me4Ph), 9.9
(C5Me4Ph), 9.8 (C5Me4Ph). Anal. Calc. for [(CpPhRh)2(l-
CH2)2(l-O2SSO2)] Æ 0.6C7H8: C, 53.55; H, 5.31. Found:
C, 53.32; H, 5.47%.
Appendix A. Supplementary data
Supplementary data associated with this article can be
found, in the online version, at doi:10.1016/j.jorganchem.
2006.08.063.
3.6. X-ray crystallography
References
All measurements were made on a Rigaku/MSC Mer-
cury CCD diffractometer with graphite monochromated
˚
[1] M. Irie, Chem. Rev. 100 (2000) 1685.
[2] H. Durr, H. Bouas-Laurent, Photochromism. Molecules and Systems,
¨
Mo Ka radiation (k = 0.71070 A). Single crystals of dimen-
sions
0.32 · 0.27 · 0.20
(RhClCl),
0.23 · 0.20 · 0.16
Elsevier, Amsterdam, 2003.
(RhCH2Me), and 0.19 · 0.11 · 0.06 (1) mm3 were mounted
on a glass fiber. The data were collected at 173
(RhClCl,RhCH2Me) or 123 (1) K to a maximum 2h value
of 55.0ꢀ. A total of 720 oscillation images were collected.
A first sweep of data was done using x scans from À80.0
to 100.0ꢀ in 0.50ꢀ step, at v = 45.0ꢀ and / = 0.0ꢀ. A second
sweep of data was made using x scans from À80.0 to
100.0ꢀ in 0.50ꢀ step, at v = 45.0ꢀ and / = 90.0ꢀ. The crys-
tal-to-detector distances were 34.97 (RhClCl,RhCH2Me) or
35.31 (1) mm, and detector swing angles were 10.03
(RhClCl,RhCH2Me) or 10.01 (1) [ꢀ]. The exposure rates were
5.0 (RhClCl and RhCH2Me), or 30.0 (1) [sec/ꢀ].
Data were collected and processed using CrystalClear
[13] software (Rigaku). A numerical absorption correction
was applied and resulted in transmission factors ranging
from 0.67 to 0.81 (RhClCl), 0.85 to 0.91 (RhCH2Me), and
0.89 to 0.97 (1). The data were corrected for Lorentz and
polarization effects.
[3] G.H. Brown, Photochromism, Wiley-Interscience, New York, 1971.
[4] H.Nakai,M.Mizuno,T.Nishioka,N.Koga,K.Shiomi,Y.Miyano,M.
Irie, B.K. Breedlove, I. Kinosita, Y. Hayashi, Y. Ozawa, T. Yonezawa,
K. Toriumi, K. Isobe, Angew. Chem. Int. Ed. 45 (2006) in press.
[5] T. Cadenbach, C. Gemel, R. Schmid, R.A. Fischer, J. Am. Chem.
Soc. 127 (2005) 17068.
[6] M.R. Churchill, S.A. Julis, F.J. Rotella, Inorg. Chem. 16 (1977) 1137.
[7] K. Isobe, A.V. de Miguel, P.M. Bailey, S. Okeya, P.M. Maitlis, J.
Chem. Soc. Dalton Trans. (1983) 1441.
[8] The stereoisomers of 1, 1-cis and 1-trans, can be only observed in
the crystal, not in the solution. We measured the variable
temperature 1H NMR spectra of 1 at À90 to 30 ꢀC in CD2Cl2.
The signal patterns show no change with temperatures in the
region and the spectra obtained are attributed to only one species.
This suggests that the CpPh ligands in 1 seem to rotate rapidly in
the solution.
[9] Y. Ohashi, Acc. Chem. Res. 21 (1988) 268.
[10] S. Ariel, S. Askari, S.V. Evans, C. Hwang, J. Jay, J.R. Scheffer, J.
Trotter, L. Walsh, Y.-F. Wong, Tetrahedron 43 (1987) 1253.
[11] Y. Ohashi, K. Yanagi, T. Kurihara, Y. Sasada, Y. Ohgo, J. Am.
Chem. Soc. 103 (1981) 5805.
[12] M. Bjo¨rgvinsson, S. Halldorsson, I. Arnason, J. Magull, D. Fenske,
J. Organomet. Chem. 544 (1997) 207.
The structure was solved by a direct method: SIR-92 [14]
for RhClCl, RhCH2Me, or SHELXL-97 [15] for 1 and expanded
using a Fourier technique. All calculations were performed
using the CrystalStructure [16,17] crystallographic software
package except for refinement, which was performed using
SHELXL-97. All non-hydrogen atoms were refined anisotrop-
ically. Hydrogen atoms, except for those of solvent mole-
cules, were placed in calculated idealized positions.
Crystallographic data are summarized in Table 1 and have
been deposited with the Cambridge Crystallographic Data
[13] CrystalClear 1.3.5: Rigaku Corporation, The Woodlands, TX, 1999.
[14] A. Altomare, G. Cascarano, C. Giacovazzo, A. Guagliardi, M.
Burla, G. Polidori, M. Camalli, J. Appl. Cryst. 27 (1994) 435.
[15] G.M. Sheldrick, SHELX97, University of Go¨ttingen, Go¨ttingen,
Germany, 1997.
[16] CrystalStructure 3.6.0: Crystal Structure Analysis Package, Rigaku
and Rigaku/MSC, The Woodlands, TX, 2004.
[17] D.J. Watkin, C.K. Prout, J.R. Carruthers, P.W. Betteridge, CRYS-
TALS Issue 10:, Chemical Crystallography Laboratory, Oxford, UK,
1996.