Structures and dynamic stereochemistry of 9-arylselanyltriptycenes: X-ray crystallographic, spectroscopic and theoretical investigations

Article abstract of DOI:10.1039/b817949b

9-(Arylselanyl)triptycenes (1: p-YC₆H₄SeTpc) should supply the planar structure (pl) around the p-YC₆H₄Se (ArSe) group in the ground state, irrespective of the p-Y substituents. 1 with Y = H (a), NMe₂

Full text of DOI:10.1039/b817949b

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PAPER
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Structures and dynamic stereochemistry of 9-arylselanyltriptycenes:
X-ray crystallographic, spectroscopic and theoretical investigationsw
Takashi Nakamoto,a Satoko Hayashi,a Waro Nakanishi,*a Mao Minourab
and Gaku Yamamotob
Received (in Montpellier, France) 14th October 2008, Accepted 23rd February 2009
First published as an Advance Article on the web 16th April 2009
DOI: 10.1039/b817949b
9-(Arylselanyl)triptycenes (1: p-YC6H4SeTpc) should supply the planar structure (pl) around the
p-YC6H4Se (ArSe) group in the ground state, irrespective of the p-Y substituents. 1 with Y = H (a),
NMe2 (b), OMe (c), Cl (d), CN (e) and NO2 (f) are prepared. Structures of 1a–d and 1f are
1
determined by X-ray analysis and dynamic H NMR spectroscopy is applied to 1a, 1c, 1e and 1f.
For convenience of discussion, the structure of 1 is defined as follows: a conformer around the
triptycyl group in 1 is called A where the Se–CAr bond is placed in the bisected area between two
phenyl planes of the triptycyl group and it is B where the bond is on a phenyl plane of the
triptycyl group. A conformer for the Ar group is named pl where the Se–CTpc bond is on the Ar
plane, while it is pd if the bond is perpendicular to the plane. The structure of 1 is confirmed to
be (A: pl) in the ground state by X-ray analysis. 1 (A: pl) changes to the equivalent one via a
transition state of 1 (B: pd) (the gear process). The activation energies are determined by dynamic
1H NMR spectroscopy: the values are 36.4, 41.6, 42.3 and o34 kJ molꢀ1 for 1a, 1e, 1f and 1c,
respectively. The MP2 level of calculations reproduced the observed values: they are evaluated to
be 34, 39, 40 and 29 kJ molꢀ1 for 1a, 1e, 1f and 1b0 (Y = NH2), respectively, where 1b0 is
employed in place of 1c. Another process (the isolated rotation process) is also operating for the
interconversion of 1 (A: pl), which proceeds via 1 (A: pd). The activation energies for the process
are predicted to be 25, 30, 30 and 20 kJ molꢀ1 for 1a, 1e, 1f and 1b0, respectively, at the MP2
level. The results demonstrate that (A: pl) is the global minimum in 1: the 1 (A: pl) structure is
well established for all Y examined in the ground state.
We searched for such selenides that can be the excellent
Introduction
standard of pl with a very small temperature dependence
77Se NMR chemical shifts (d(Se)) are widely applied to
determine structures1–4 and routinely follow reactions,1,5 since
they are sharply sensitive to structural changes in selenium
compounds.1–4 We have pointed out the importance of the
orientational effect of p-YC6H4Se (ArSe) on d(Se) in ArSeR,
together with the mechanism, for the better understanding the
structures of ArSeR in solutions based on d(Se).4 Typical
conformers in relation to the orientational effect in ArSeR
are planar (pl) and perpendicular (pd), where the Se–CR bond
in ArSeR is on the Ar plane in pl and it is perpendicular to the
plane in pd.6,7
of d(Se).8,9 9-(Arylselanyl)triptycenes (1: p-YC6H4SeTpc;
ArSeTpc) should be an excellent candidate for pl around the
ArSeCTpc moiety in the ground state. To employ 1 as the
standard for pl, it is necessary to establish the stereochemistry
containing the structures in the ground state and the thermal
behavior of 1. 1 were prepared for Y = H (a), NMe2 (b), OMe
(c), Cl (d), CN (e) and NO2 (f), as shown in Chart 1.
The structures are determined by X-ray analysis for 1a–d
and 1f. Dynamic 1H NMR spectroscopy was applied on
1a, 1c, 1e and 1f.
a Department of Material Science and Chemistry, Faculty of Systems
Engineering, Wakayama University, 930 Sakaedani, Wakayama,
640-8510, Japan. E-mail: nakanisi@sys.wakayama-u.ac.jp;
Fax: +81 73 457 8253; Tel: +81 73 457 8252
b Department of Chemistry, School of Science, Kitasato University,
Kitasato, Sagamihara, Kanagawa, 228-8555, Japan
w Electronic supplementary information (ESI) available: ORTEP
drawings of 1c and 1d. NMR spectra of the aromatic protons of 1a,
1c and 1e in CD2Cl2 at various temperatures. Results of QC calcula-
tions on 1a, 1b0, 1e and 1f for (A: pl), (A: pd) and (B: pd) at the MP2
level. Cartesian coordinates for optimized structures of 1a, 1b0, 1e and
1f. CCDC reference numbers 704856 for 1a, 704857 for 1b, 704858 for
1c, 704859 for 1d and 704860 for 1f. For ESI and crystallographic data
in CIF or other electronic format see DOI: 10.1039/b817949b
Chart 1 Structure of 1 (A: pl).
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Fig. 1 ORTEP drawing of 1a with atomic numbering scheme for
selected atoms (50% probability thermal level): (a) side view and
(b) top view.
Scheme 1 Interconversion between conformers in 1.
We call the conformers around the Se–CTpc bond in 1 A and
B: A corresponds to a conformer where the Ar group is in the
bisected area between two phenyl planes of the triptycyl group
and it is B if the Ar group is on a phenyl plane of the triptycyl
group in 1. Scheme 1 shows the (A: pl), (A: pd) and (B: pd)
conformers, together with the interconversion process in 1.10
Isolated rotation (IR) may occur around the Se–CAr bond,
converting (A: pl) into (A: pd) and thence into the equivalent
form (A: pl0) by further rotation, where the primes imply the
topomeric structures, although (A: pl0) is not shown in
Scheme 1. There are three equivalent conformations in each
of (A: pl) and (A: pd). Interconversion between (A: pl) and
(A0: pl0) may occur via (B: pd). This process is referred to as
gear rotation (GR). There are three equivalent conformers
also in (B: pd).
Fig. 2 ORTEP drawing of 1bA (a) and 1bB (b) with atomic
numbering scheme for selected atoms (50% probability thermal level),
top view.
Here we discuss the structures of 1 in the ground state based
on X-ray crystallographic analysis and dynamic stereo-
chemistry by 1H DNMR spectroscopy. The energy profile
of 1 will also be discussed by employing quantum chemical
(QC) calculations.
Results and discussion
Structure of 9-(p-YC6H4SeTpc)
X-Ray crystallographic analyses are carried out for suitable
single crystals of 1a–d and 1f. Whereas only one type of
structure corresponds to each of them in the crystals
for 1a, 1c, 1d and 1f, 1b crystallizes with two symmetrically
independent molecules in the asymmetric unit: the two
independent molecules are called 1bA and 1bB. Fig. 1–3 show
the structures of 1a, 1b (1bA and 1bB) and 1f, respectively.
Those of 1c and 1d are shown in the Electronic supplementary
information (ESIw) (Fig. S1 and S2, respectively). Table 1
collects the selected interatomic distances, angles and torsional
angles of 1a–d and 1f, necessary for the discussion.
Fig. 3 ORTEP drawing of 1f with atomic numbering scheme for
selected atoms (50% probability thermal level), top view.
of +C1SeC21C22 for the former are 4–61, whereas those for
the latter amount to 10–281. The crystal packing effect would
be responsible for the deviations. The shallow energy surface
for 1b and 1c, relative to 1a, 1d and 1f would also affect on the
observed results. The steric compression seems small for these
compounds.
The structures of 1a–d and 1f are shown to be all (A: pl) in
crystals: the +C21SeC1C2 values are close to 1801 (or ꢀ1801).
While the Se–C1 lengths are almost constant for the
compounds under the measurement conditions, the lengths
for Se–C21 of 1d and 1f are slightly shorter than those of 1a–c.
The structures are close to Cs symmetry for 1a, 1d and 1f but
some deviations are observed for 1b and 1c: the magnitudes
The p–p conjugation of the p(Se)–p(C6H4)–p(Y) type
should affect the stability of the conformers. Y of acceptors
stabilize (A: pl) through the favorable p–p conjugation,
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Table 1 Selected interatomic distances (A), angles (1) and torsional angles (1) of 1a–d and 1f
Compound
Y
1a
1bA
1bB
1c
1d
1f
H
NMe2
NMe2
OMe
Cl
NO2
Se–C1
Se–C21
1.9606(16)
1.9218(16)
1.953(2)
1.921(2)
1.961(2)
1.921(2)
1.9603(18)
1.9228(18)
1.9598(19)
1.9162(19)
1.958(3)
1.902(3)
C21–Se–C1
Se–C21–C22
Se–C21–C26
104.35(7)
114.31(12)
125.92(13)
103.44(10)
114.85(17)
126.89(17)
107.42(10)
114.53(19)
127.14(18)
104.52(7)
115.12(13)
125.63(14)
105.29(8)
114.59(14)
125.60(15)
105.31(12)
114.1(2)
125.7(2)
C21–Se–C1–C2
C21–Se–C1–C14
C21–Se–C1–C15
C1–Se–C21–C22
C1–Se–C21–C26
Se–C1–C2–C7
177.66(10)
ꢀ65.19(12)
61.10(13)
175.91(12)
ꢀ4.61(16)
179.55(11)
ꢀ176.44(11)
179.28(11)
ꢀ177.68(15)
ꢀ63.88(18)
62.23(17)
170.23(14)
ꢀ72.46(18)
53.17(18)
ꢀ173.82(11)
ꢀ56.32(14)
68.28(14)
168.52(13)
ꢀ10.32(18)
179.52 (12)
ꢀ176.70 (12)
177.18(12)
178.22(12)
ꢀ64.45(14)
61.00(15)
177.25(17)
ꢀ65.9(2)
59.5(2)
ꢀ175.02(17)
ꢀ154.65(18)
ꢀ174.62(14)
ꢀ174.4(2)
9.5(2)
28.3(2)
5.86(18)
4.4(3)
179.48(15)
ꢀ176.35(15)
176.84(15)
179.60 (16)
ꢀ175.68(16)
174.64(16)
179.74(13)
ꢀ174.95(13)
175.48(13)
179.58(18)
ꢀ175.64(18)
175.98(18)
Se–C1–C14–C9
Se–C1–C15–C20
whereas Y of donors will destabilize (A: pl) through unfavor-
able interactions between electron rich p(Se) and p(Y).
Consequently, the equilibrium between (A: pl) and (A: pd)
would be facilitated by Y of donors. Therefore, we must
carefully examine the structure of 1 having Y of strong donors
such as Y = NMe2. As shown in Fig. 2, the structure of 1b
(Y = NMe2) is apparently (A: pl), which strongly suggests that
the structure of all members of 1 is (A: pl). The structures of
1a–d and 1f determined by X-ray crystallographic analysis
support the (A: pl) structure of 1 in the ground state for all Y
shown in Chart 1.
Scheme 2 illustrates the transition states for GR in 1a, 2a and
3a. The low GR barrier in 2a has been ascribed to the
divalency of the oxygen. The eclipsing interaction at the
transition states should be considered only between the phenyl
group and one of o-benzeno bridges in 2a (B: pd). However,
the eclipsed interaction between the methylene hydrogens and
the o-benzeno bridges should also be considered in 3a (B: pd).
The transition state must be more destabilized as the Z–CTpc
bond length becomes shorter. However, the effect in 2a relative
to 3a is completely overshadowed by the effect of valency in
these cases.12 The GR barrier for PhSeTpc (1a) is expected to
be less than that for 2a if the bond length effect is considered
(Se in 1a is divalent). However, the GR barrier for 1a
(36.4 kJ molꢀ1) is larger than that of 2a. Mechanisms other
than those of the valency and the bond length, such as the
angle effect, must also be operating.
After confirmation of the 1 (A: pl) structure in the ground
state, the next extension is to clarify the dynamic stereo-
chemistry of 1.
1
Dynamic H NMR spectroscopy
The structures determined by X-ray crystallographic
1
analysis and the results of H DNMR spectroscopy confirm
1H NMR spectra were measured for 1a, 1c, 1e and 1f at
various temperatures in CD2Cl2 on a 600 MHz spectrometer
for 1H nuclei. Fig. 4 shows the spectra for 1f, for an example.
Fig. 4 also contains the calculated line-shape change of
aromatic protons in the triptycyl group for 1f. The activation
energy for rear rotation (GR) is evaluated to be 42.3 kJ molꢀ1
for 1f by analyzing the temperature dependent 1H NMR
spectra shown in Fig. 4. The observed spectra of 1a, 1c and
1e are given in Fig. S3, S4 and S5 of the ESI,w respectively.
Similarly to the case of 1f, the activation energy for GR of
1e is evaluated to be 41.6 kJ molꢀ1. The energy is evaluated to
be 36.4 kJ molꢀ1 for GR in 1a although the signals are not
separated completely even at ꢀ102 1C. Only the upper limit of
the parameter was estimated for 1c due to the poor signal
separation: the upper limit is 34 kJ molꢀ1. Table 2 summarizes
rate constants and free energies of activation for GR in 1.11,12
The dynamic spectra demonstrate that the structures of 1a, 1c,
1e and 1f are all (A: pl) in the ground state: (B: pd) appears at
the transition state of GR. The activation energies for GR
seem all around 30–40 kJ molꢀ1 for 1a–f (see also Table S2 of
the ESIw).
the 1 (A: pl) structure in the ground state. Attention was then
turned to the energy profiles of the isolated rotation (IR)
process in 1 which are not determined by 1H DNMR spectro-
scopy. QC calculations were thus performed on (A: pl), (A: pd)
and (B: pd) for 1a, 1b0 (p-H2NC6H4SeTpc), 1e and 1f.
QC calculations
QC calculations are performed on 1a, 1b0, 1e and 1f using the
Gaussian 03 program13 at the density functional theory (DFT)
level (B3LYP)14,15 and the Møller–Plesset second order energy
correlation (MP2)16 level. Calculations at the MP2 level are
more reliable relative to those at the DFT level when the
transition states are examined. Therefore, results at the MP2
level are employed for the discussion.17 The (A: pd) and (B: pd)
structures must correspond to the transition states for the IR
and GR processes in 1, respectively, while (A: pl) is the ground
state. QC calculations support the expectation.
Indeed, the results of QC calculations essentially correspond
to those in the gas phase, but the factors to control and/or
stabilize the structures in gas phase must also operate in the
solid state and in solution. Therefore, it is instructive to
consider those predicted by QC calculations, although we
The GR barrier for 9-(phenoxy)triptycene (2a: PhOTpc)
is reported to be ca. 29 kJ molꢀ1, which is much less than the
value of 44.8 kJ molꢀ1 for 9-(benzyl)triptycene (3a: PhCH2Tpc).12
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Fig. 4 Observed 1H NMR spectra due to the aromatic proton region of 1f in CD2Cl2 at various temperatures (a) and the calculated spectra with
the best-fit rate constants for the aromatic protons of the triptycyl group for the GR process (b).
Table 2 Rate constants and free energies of activation of the GR
process in 1
1a, 1b0, 1e and 1f can be discussed by assuming (A: pl), (A: pd)
and (B: pd) of Cs symmetry as the ground state structures,
(TS: IR) and (TS: GR), respectively, except for 1b0 (A: pl). The
ground state of 1b0 (A: pl) must be of C1 symmetry.
QC calculations are performed on 1a, 1b0, 1e and 1f,
employing the 6-311+G(d) basis sets for Se and the
6-31G(d) basis sets for O, N, C and H (basis sets-B) at
the MP2 level and results are shown in Table S2 of the ESI.w
The results are also illustrated in Fig. 5. (B: pd) are predicted to
be less stable than (A: pl) by 34, 29, 39 and 40 kJ molꢀ1 for 1a,
1b0, 1e and 1f, respectively, on the potential energy surface
Compound
Y
kGR/sꢀ1
DGzGR/kJ molꢀ1
Ta/1C
1a
1c
1e
1f
H
ca. 90
4100
ca. 84
ca. 69
36.4
o34
41.6
ꢀ93
ꢀ100
ꢀ70
OMe
CN
NO2
42.3
ꢀ68
a
Coalescence temperature.
Scheme 2 Illustration of the transition states for GR in 1a, 2a and 3a.
must consider the crystal packing effect in crystals and the
solvent effect in solutions, since they are often larger than the
predicted factors.17
QC calculations are performed on 1a employing the
6-311+G(d) basis sets for Se and the 4-31G basis sets for C
and H (basis sets-A) at the MP2 level. Three structures, 1a
(A: pl), 1a (A: pd) and 1a (B: pd) of Cs symmetry, are
optimized. Frequency analysis is applied on the optimized
structures with the same method. Table S1 of ESIw shows the
results. Whereas all frequencies are positive for 1a (A: pl), only
one imaginary frequency is predicted for each of 1a (A: pd) and
1a (B: pd). The results demonstrate that 1a (A: pl), 1a (A: pd)
and 1a (B: pd) of Cs symmetry are the ground state structure,
transition state for IR (TS: IR) and (TS: GR), respectively.
Therefore, it would be rationalized that the energy profiles of
Fig. 5 Energy profiles for the conformers in 1 (values evaluated using
basis sets-B at the MP2 level being employed).
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when calculated using basis sets-B at the MP2 level. The
frequency analysis was unsuccessful due to the memory
capacity of our calculation conditions. However, the evaluated
values were very close to the observed activation energies for
GR of the corresponding compounds, respectively. The
evaluated activation energies for GR on the potential energy
surface with the calculation method reproduced the observed
values for GR.
It is of interest if the Y dependence in the energy profiles of 1
containing (A: pl), (A: pd) and (B: pd) is a reflection of the
p(Se)–p(Ar) conjugation. Investigations into p–p conjugation
of the type are in progress.
Experimental
General considerations
What is the energy profile of IR? The (A: pd) structures are
predicted to be less stable than (A: pl) by 25, 20, 30 and
30 kJ molꢀ1 for 1a, 1b0, 1e and 1f, respectively, when calcu-
lated employing the basis sets-B at the MP2 level (see Fig. 5
and Table S2 of the ESIw). The values must correspond to
(TS: IR), which are smaller than the corresponding (TS: GR).
The activation energies evaluated for IR are expected to be
reliable judging from the discussion for the evaluated values in
GR with the same method. The results demonstrate that the
structures of 1 are (A: pl) in the ground state, although no
experimental data are available for IR.
Manipulations were performed under a nitrogen or an argon
atmosphere with standard vacuum-line techniques. Glassware
was dried at 130 1C overnight. Solvents and reagents were
purified by standard procedures as necessary. The melting
points were determined on a Yanako MP-S3 melting point
apparatus and are uncorrected. NMR spectra were recorded at
25 1C on a JEOL AL-300 spectrometer (1H, 300 MHz; 13C,
75.5 MHz; 77Se, 57.3 MHz) and at various temperatures
in CD2Cl2 on a Bruker AVANCE II 600 spectrometer
(1H, 600 MHz). The 1H, 13C and 77Se chemical shifts are given
in parts per million relative to those of Me4Si, internal CDCl3
in the solvent and external Me2Se, respectively. Flash column
chromatography was performed with 300–400 mesh silica gel
and basic alumina and analytical thin layer chromatography
was performed on precoated silica gel plates (60F-254) with
the systems (v/v) indicated.
The evaluated activation energies in both IR and GR
processes change depending on Y. However, the energy
differences between the two processes (DDE = DE(B: pd) ꢀ
DE(A: pd)) are very similar to each other irrespective of Y: the
differences are 9–10 kJ molꢀ1 when calculated with the basis
sets-B at the MP2 level. The DDE values must be equal to
DE(B, A) (= E(B: pd) ꢀ E(A: pd)). Therefore, the results show
that the energy differences between (B: pd) and (A: pd) are
almost constant irrespective of Y. Fig. 5 shows the energy
profiles of 1. It is worthwhile to comment that DDE must
contain the intrinsic energy difference between 1 (B: pd)
and 1 (A: pd): DDE (= DE(B, A)) are almost constant
whereas DE(B: pd) (= DE(B: pd) ꢀ E(A: pl)) and DE(A: pd)
(= E(A: pd) ꢀ E(A: pl)) are affected by Y.
Syntheses
9-(Phenylselanyl)triptycene (1a). Under an argon atmo-
sphere, to
a
solution of 9-bromotriptycene18 (510 mg,
1.50 mmol) in 12 mL of benzene and 40 mL of diethyl ether
at 0 1C was added 1.0 mL of n-BuLi (1.62 mmol, 1.62 N). After
stirring for 1 h, the fine suspension of 9-triptycyllithum was
added to an ethereal solution of 1.0 equiv. benzeneseleno-
bromide. After stirring for 1 h. at 0 1C, the reaction was
quenched by acetone (4 mL), and the solvent was removed
in vacuo. 100 mL of benzene and 6% aqueous solution of
hydrochloric acid were added. The organic layer was separated
and washed with 50 mL of water, 50 mL of 10% aqueous
solution of sodium carbonate, 50 mL of saturated aqueous
solution of sodium hydrogen carbonate, 50 mL of water, and
dried over sodium sulfate. The crude product was purified by
column chromatography (SiO2, benzene–hexane 1 : 2) and
recrystallized from dichloromethane and hexane. 1a was iso-
lated in 32% yield as a colorless solid (195 mg): mp
Conclusion
9-(Arylselanyl)triptycenes (1: p-YC6H4SeTpc) should be
excellent candidates for the standard of pl. To employ 1 as
the standard for pl, it is necessary to establish the ground state
structures of 1 and the dynamic stereochemistry including the
thermal behavior of 1. Compounds 1 with Y = H (a), NMe2
(b), OMe (c), Cl (d), CN (e) and NO2 (f) were prepared and the
structures of 1a–d and 1f determined by X-ray analysis.
Dynamic 1H NMR spectroscopy was applied on 1a, 1c, 1e
and 1f. 1 (A: pl) is demonstrated to be more stable than 1
(B: pd) by 42 kJ molꢀ1 for Y = CN and NO2 and 36 kJ molꢀ1
(or less) for Y = H and OMe. QC calculations well repro-
duced the experimental results and supported the expectation.
1a (A: pd) and 1a (B: pd) are evaluated to be less stable than 1a
(A: pl) by 25 and 34 kJ molꢀ1, respectively, when calculated at
the MP2 level with the basis sets-B. Even for Y of donating
NH2 group, 1b0 (A: pd) and 1b0 (B: pd) are predicted to be less
stable than 1b0 (A: pl) by 20 and 29 kJ molꢀ1, respectively,
when calculated at the same method. The results strongly
support that the structures of 1 are (A: pl) for all Y examined
containing Y = NMe2 and OMe both in crystals and
solutions. Consequently, the structures of ArSeR in solution
can be analyzed from the viewpoint of the orientational effect
employing the set of d(Se: 1).
1
271.0–272.5 1C; H NMR (300 MHz, CDCl3, d, ppm, TMS)
5.44 (s, 1H), 6.92 (dt, J = 1.4, 7.6 Hz, 3H), 7.01 (dt, J = 1.3,
7.4 Hz, 3H), 7.07–7.11 (m, 3H), 7.16–7.20 (m, 2H), 7.40 (dd,
J = 1.2, 7.2 Hz, 3H), 7.54 (d, J = 7.4 Hz, 3H); 13C NMR
(75.5 MHz, CDCl3, d, ppm, TMS) 54.2, 61.0, 123.3 (3C), 124.9
(3J(Se,C) = 12.1 Hz, 3C), 125.0 (3C), 125.4, 125.8 (3C), 128.7
(meta-Ph, 2C), 129.9 (2J(Se,C) = 15.6 Hz, 2C), 130.7, 144.0
(2J(Se,C) = 6.2 Hz, 3C), 145.3 (3C); 77Se NMR (57.3 MHz,
CDCl3, d, ppm, Me2Se) 259.0. Anal. Calc. for C26H18Se, C,
76.28; H, 4.43%. Found: C, 76.42; H, 4.33%.
9-[p-(N,N-Dimethylamino)phenylselanyl]triptycene (1b). Under
a nitrogen atmosphere, to a suspension of di-9-triptycyl
diselenide19 (900 mg, 1.38 mmol) and 40 mL of THF
at 0 1C was added NaBH4 (110 mg, 2.76 mmol) in
small amount of water.
A solution of 6.0 equiv. of
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p-(N,N-dimethylamino)phenyldiazonium chloride was added
at 0 1C. If an orange precipitate appeared, NaBH4 (110 mg,
2.76 mmol) in an aqueous THF solution was added to the
reaction solution. Dichloromethane (200 mL) and 2%
aqueous solution of sodium hydroxide was added. The organic
layer was separated and washed with a 10% aqueous solution
of sodium carbonate and then a saturated aqueous solution
of sodium hydrogen carbonate, and dried over potassium
carbonate. The crude product was purified by column
chromatography (SiO2, benzene–hexane 1 : 1 as eluent) and
recrystallization from hexane. 1b was isolated in 6% yield as
pale yellow needles (19 mg): mp 227.5–229.0 1C; 1H NMR
(300 MHz, CDCl3, d, ppm, TMS) 2.87 (s, 6H), 5.42 (s, 1H),
6.55 (d, J = 9.0 Hz, 2H), 6.94 (dt, J = 1.5, 7.5 Hz, 3H), 7.01
(dt, J = 1.3, 7.3 Hz, 3H), 7.10 (d, J = 9.1, 2H), 7.40 (dd, J =
1.3 and 7.1, 3H), 7.60 (d, J = 7.4, 3H); 13C NMR (75.5 MHz,
CDCl3, d, ppm, TMS) 40.5 (2C), 54.3, 60.5, 113.4 (2C), 123.1
(3C), 125.0 (3C), 125.1 (3C), 125.1, 125.6 (3C), 131.0
(2J(Se,C) = 15.3 Hz, 2C), 144.5 (2J(Se,C) = 6.2 Hz, 3C),
145.4 (3C), 148.6; 77Se NMR (57.3 MHz, CDCl3, d, ppm,
Me2Se) 238.5. Anal. Calc. for C28H23NSe; C, 74.33; H, 5.12;
N, 3.10%. Found: C, 74.13; H, 5.11; N, 3.14%.
9-(p-Chlorophenylselanyl)triptycene (1d). Following the
procedure used for the preparation of 1a, 1d was obtained in
15% yield as colorless solid: mp 237.0–238.0 1C; 1H NMR
(300 MHz, CDCl3, d, ppm, TMS) 5.45 (s, 1H), 6.95 (dt, J =
1.4, 7.6 Hz, 3H), 7.04 (dt, J = 1.2, 7.4 Hz, 3H), 7.10 (s, 4H),
7.42 (dd, J = 1.2, 7.2 Hz, 3H), 7.48 (d, J = 7.5 Hz, 3H); 13C
NMR (75.5 MHz, CDCl3, d, ppm, TMS) 54.2, 61.3, 123.4
(3C), 124.6 (3J(Se,C) = 12.5 Hz, 3C), 125.1 (3C), 125.9 (3C),
128.9 (2C), 128.9, 131.2 (2J(Se,C) = 16.2 Hz, 2C), 131.4, 143.6
(2J(Se,C) = 6.2 Hz, 3C), 145.3 (3C); 77Se NMR (57.3 MHz,
CDCl3, d, ppm, Me2Se) 262.7. Anal. Calc. for C26H17ClSe, C,
70.36; H, 3.86%. Found: C, 70.48; H, 3.81%.
9-(p-Cyanophenylselanyl)triptycene (1e). Following the
procedure used for the preparation of 1b, 1e was obtained in
24% yield as colorless solid: mp 252.0–253.5 1C; 1H NMR
(300 MHz, CDCl3, d, ppm, TMS) 5.48 (s, 1H), 6.95 (dt, J =
1.3, 7.5 Hz, 3H), 7.06 (dt, J = 1.1, 7.5 Hz, 3H), 7.26 (d, J =
9.0 Hz, 2H), 7.36 (d, J = 8.8 Hz, 2H), 7.43 (d, J = 7.5 Hz,
3H), 7.44 (dd, J = 1.2, 7.2 Hz, 3H); 13C NMR (75.5 MHz,
CDCl3, d, ppm, TMS) 54.1, 62.0, 108.9, 118.8, 124.3 (3C),
125.1 (3C), 126.2 (3C), 130.5 (2J(Se,C) = 16.2 Hz, 2C), 131.8
(3J(Se,C), 5.0 Hz, 2C), 138.6, 143.2 (3C), 145.2 (3C); 77Se
NMR (57.3 MHz, CDCl3, d, ppm, Me2Se) 287.6. Anal. Calc.
for C60H46N2Se2 (1e ꢂ 2 and cyclohexane), C, 75.62; H, 4.87;
N, 2.94%. Found: C, 75.67; H, 4.84; N, 2.88%.
9-(p-Methoxyphenylselanyl)triptycene (1c). Following the
procedure used for the preparation of 1a, 1c was obtained in
1
21% yield as colorless prisms: mp 192.0–193.0 1C; H NMR
(300 MHz, CDCl3, d, ppm, TMS) 3.72 (s, 3H), 5.44 (s, 1H),
6.71 (d, J = 9.0 Hz, 2H), 6.94 (dt, J = 1.4, 7.5 Hz, 3H), 7.02
(dt, J = 1.3, 7.4 Hz, 3H), 7.13 (d, J = 9.0 Hz, 2H), 7.40
(dd, J = 1.3, 7.2 Hz, 3H), 7.55 (d, J = 7.5 Hz 3H); 13C NMR
(75.5 MHz, CDCl3, d, ppm, TMS) 54.3, 55.2, 60.9, 114.7 (2C),
120.4, 123.3 (3C), 124.9 (3J(Se,C) = 11.5 Hz, 3C), 125.0 (3C),
125.7 (3C), 131.1 (2J(Se,C) = 15.7 Hz, 2C), 144.2 (3C), 145.4
(3C), 157.8; 77Se NMR (57.3 MHz, CDCl3, d, ppm, Me2Se)
247.7. Anal. Calc. for C27H20OSe: C, 73.80; H, 4.59%. Found:
C, 73.92; H, 4.63%.
9-(p-Nitrophenylselanyl)triptycene (1f). Under a nitrogen
atmosphere, to a suspension of di-9-triptycyl diselenide17
(500 mg, 0.75 mmol) in ethanol (15 mL) at 0 1C was added
NaBH4 (270 mg, 6.78 mmol). p-Nitroiodobenzene was added
to the reaction mixture. After refluxing for 3 h, the reaction
mixture was poured into 100 g of ice-water. The precipitate
was separated by using suction filtration. The crude product
was purified by column chromatography (SiO2, benzene–
hexane 1 : 1) and recrystallized from dichloromethane and
cyclohexane. 1f was isolated in 57% yield as a bright yellow
Table 3 Crystallographic data for 1a–d and 1f
1a
1b
1c
1d
1f
Empirical formula
Mr
C26H18Se
409.36
C28H23NSe
452.43
C27H20OSe
439.39
C26H17ClSe
443.81
C26H17NO2Se
454.37
Colorless plate
233
Yellow needle
233
Triclinic
Colorless needle
233
Colorless plate
233
Pale yellow plate
233
Orthorhombic
Pbca (#61)
7.9805(4)
T/K
Crystal system
Space group
a/A
b/A
c/A
a/1
Monoclinic
P21/n (#14)
9.8178(5)
15.3715(7)
12.2627(6)
Monoclinic
P21/n (#14)
11.5331(11)
14.2581(14)
12.4437(12)
Orthorhombic
Pbca (#61)
11.8868(6)
13.9067(7)
22.8836(11)
ꢀ
P1 (#2)
9.6439(4)
11.2233(5)
20.4121(8)
74.692(1)
87.418(1)
77.850(1)
2082.08(15)
4
1.443
928
8849
545
14.0346(7)
34.5168(18)
b/1
91.809(1)
91.798(1)
g/1
V/A3
1849.69(16)
4
1.470
832
4133
2045.2(3)
4
1.427
896
4570
3782.8(3)
8
1.559
1792
4302
3866.0(3)
8
1.561
1840
4416
Z
Dc/g cmꢀ3
F(000)
Reflections observed [I 4 2s(I)]
Parameters
244
263
253
271
R1 [I 4 2s(I)]
R1 [all data]
wR2 [I 4 2s(I)]
wR2 [all data]
Goodness-of-fit on F2
0.0243
0.0310
0.0600
0.0632
1.024
0.0340
0.0420
0.0933
0.0980
1.074
0.0283
0.0365
0.0732
0.0772
1.064
0.0269
0.0369
0.0733
0.0855
1.131
0.0385
0.0542
0.0968
0.1117
1.170
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solid (394 mg): mp 293.0–294.0 1C; 1H NMR (300 MHz,
CDCl3, d, ppm, TMS) 5.49 (s, 1H), 6.96 (dt, J = 1.3, 7.6 Hz,
3H), 7.07 (dt, J = 1.2, 7.4 Hz, 3H), 7.32 (d, J = 9.1 Hz, 2H),
7.41–7.47 (m, 6H), 7.95 (d, J = 9.1 Hz, 2H); 13C NMR (75.5
MHz, CDCl3, d, ppm, TMS) 54.1, 62.2, 123.4 (2C), 123.7 (3C),
124.3 (3C), 125.1 (3C), 126.2 (3C), 130.3 (2J(Se,C) = 16.2 Hz,
2C), 141.3, 143.0 (3C), 145.2 (3C), 145.7; 77Se NMR (57.3
MHz, CDCl3, d, ppm, Me2Se) 292.6. Anal. Calc. for
C26H17NO2Se, C, 68.73; H, 3.77; N, 3.08%. Found: C,
68.72; H, 3.91; N, 3.11%.
2 (a) S. Gronowitz, A. Konar and A.-B. Hornfeldt, Org. Magn.
Reson., 1977, 9, 213–217; (b) G. P. Mullen, N. P. Luthra,
R. B. Dunlap and J. D. Odom, J. Org. Chem., 1985, 50,
811–816; (c) G. A. Kalabin, D. F. Kushnarev, V. M. Bzesovsky
and G. A. Tschmutova, J. Org. Magn. Reson., 1979, 12, 598–604;
(d) G. A. Kalabin, D. F. Kushnarev and T. G. Mannafov, Zh. Org.
Khim., 1980, 16, 505–512; (e) W. Nakanishi, S. Hayashi and
T. Uehara, Eur. J. Org. Chem., 2001, 3933–3943.
3 (a) S. Hayashi and W. Nakanishi, J. Org. Chem., 1999, 64,
6688–6696; (b) W. Nakanishi, S. Hayashi and H. Yamaguchi,
Chem. Lett., 1996, 947–948; (c) W. Nakanishi, S. Hayashi,
A. Sakaue, G. Ono and Y. Kawada, J. Am. Chem. Soc., 1998,
120, 3635–3640; (d) W. Nakanishi and S. Hayashi, J. Org. Chem.,
2002, 67, 38–48.
X-Ray structure determination. Single crystals of 1a were
obtained from solutions of n-hexane–ethyl acetate (2 : 1, v/v)
after slow evaporation of the solvent at room temperature, 1b,
1c and 1f from solutions of n-hexane–dichloromethane
(2 : 1, v/v) and 1d from solutions of cyclohexane. Diffraction
data were collected on a Bruker Apex-II CCD diffractometer
equipped with a graphite-monochromated Mo-Ka radiation
source (l = 0.71070 A). The structures were solved by direct
methods (SHELXS-97),20 and refined by full-matrix least-
square methods on F2 for all reflections (SHELXL-97)21 with
all non-hydrogen atoms anisotropic and all hydrogen atoms
isotropic. Table 3 lists the parameters for 1a–d and 1f.
4 (a) W. Nakanishi and S. Hayashi, Chem. Lett., 1998, 523–524;
(b) W. Nakanishi and S. Hayashi, J. Phys. Chem. A, 1999, 103,
6074–6081.
5 (a) Organic Selenium Compounds: Their Chemistry and Biology,
ed. D. L. Klayman, W. H. H. Gunther, Wiley, New York, 1973;
(b) The Chemistry of Organic Selenium and Tellurium Compounds,
ed. S. Patai and Z. Rappoport, John-Wiley and Sons, New York,
1986, vols. 1 and 2; (c) Organic Selenium Chemistry, ed. D. Liotta,
Wiley-Interscience, New York, 1987; (d) Organoselenium
Chemistry:
A practical Approach, ed. T. G. Back, Oxford
University Press, Oxford, 1999; (e) Organoselenium Chemistry
Modern Developments in Organic Synthesis, Top. Curr. Chem.,
ed. T. Wirth, Springer, Berlin–Heidelberg–New York–London–
Paris–Tokyo, 2000.
6 W. Nakanishi, S. Hayashi and T. Uehara, J. Phys. Chem. A, 1999,
103, 9906–9912.
Analysis of 1H DNMR. The temperature-dependent spectra
of the aromatic protons of 1e and 1f (and 1a) were analyzed
using an NMR simulation program, gNMR22 (see Fig. 4, for
example).
7 S. Hayashi, H. Wada, T. Ueno and W. Nakanishi, J. Org. Chem.,
2006, 71, 5574–5585.
8 The importance of relative conformations between substituents
and probe sites in the substituent effects is pointed out. See, for
example, K. Bordwen and E. J. Grubbs, Angular Dependence of
Dipolar Substituent Effects, in Progress in Physical Organic
Chemistry, ed. R. W. Taft, John Wiley & Sons, New York, 1993,
vol. 19, pp. 183–224. See also refs. cited therein.
9 Sets of d(Se) in 9-(arylselanyl)anthracenes (I: p-YC6H4SeAtc),
d(Se: I) and 1-(arylselanyl)anthraquinones (II: p-YC6H4SeAtq),
d(Se: II), are demonstrated to be the standards of pl and pd,
respectively, based on the theoretical and experimental investiga-
tions. Although the temperature dependence of d(Se) is very small
in II (B: pd), that in I (A: pl) is not so small, which may show
that the structure of I (A: pl) is unstable relative to that of
II (B: pd). See, (a) W. Nakanishi, S. Hayashi, D. Shimizu
and M. Hada, Chem.–Eur. J., 2006, 12, 3829–3846; (b) S. Hayashi
and W. Nakanishi, Bioinorg. Chem. Appl., 2006, 1–13, DOI:
10.1155/BCA/2006/79327.
QC calculations. QC calculations are performed on 1a, 1b0,
1e and 1f using the Gaussian 03 program.13 The Møller–
Plesset second order energy correlation (MP2)16 level is also
applied with the 6-311+G(d) basis sets for Se and the 4-31G
basis sets for C and H (basis sets-A). The 6-311+G(d) basis
sets for Se and the 6-31G(d) basis sets for C and H (basis
sets-B) are also employed for the calculations at the MP2
level. The density functional theory (DFT) level of the Becke
three-parameter hybrid functional combined with the
Lee–Yang–Parr correlation functional (B3LYP)14,15 is also
applied with the 6-311+G(d) basis sets being employed for
Se and the 6-311G(d,p) basis sets for C and H.
10 The A and B conformations are involved for the anthryl group in I
and the anthraquinolyl group in II and pl and pd for the aryl
groups in I and II9.
11 G. Yamamoto, Tetrahedron, 1990, 46, 2761–2772.
Acknowledgements
12 G. Yamamoto, K. Inoue, H. Higuchi, M. Yonebayashi, Y. Nabeta
and J. Ojima, Bull. Chem. Soc. Jpn., 1998, 71, 1241–1248.
13 M. J. Frisch, G. W. Trucks, H. B. Schlegel, G. E. Scuseria,
M. A. Robb, J. R. Cheeseman, J. A. Montgomery, Jr,
T. Vreven, K. N. Kudin, J. C. Burant, J. M. Millam,
S. S. Iyengar, J. Tomasi, V. Barone, B. Mennucci, M. Cossi,
G. Scalmani, N. Rega, G. A. Petersson, H. Nakatsuji, M. Hada,
M. Ehara, K. Toyota, R. Fukuda, J. Hasegawa, M. Ishida,
T. Nakajima, Y. Honda, O. Kitao, H. Nakai, M. Klene, X. Li,
J. E. Knox, H. P. Hratchian, J. B. Cross, V. Bakken, C. Adamo,
J. Jaramillo, R. Gomperts, R. E. Stratmann, O. Yazyev,
A. J. Austin, R. Cammi, C. Pomelli, J. W. Ochterski,
P. Y. Ayala, K. Morokuma, G. A. Voth, P. Salvador,
J. J. Dannenberg, V. G. Zakrzewski, S. Dapprich, A. D. Daniels,
M. C. Strain, O. Farkas, D. K. Malick, A. D. Rabuck,
K. Raghavachari, J. B. Foresman, J. V. Ortiz, Q. Cui,
A. G. Baboul, S. Clifford, J. Cioslowski, B. B. Stefanov, G. Liu,
A. Liashenko, P. Piskorz, I. Komaromi, R. L. Martin, D. J. Fox,
T. Keith, M. A. Al-Laham, C. Y. Peng, A. Nanayakkara,
M. Challacombe, P. M. W. Gill, B. Johnson, W. Chen,
M. W. Wong, C. Gonzalez and J. A. Pople, GAUSSIAN 03
(Revision D.05), Gaussian, Inc., Pittsburgh, PA, 2004.
This work was partially supported by a Grant-in-Aid for
Scientific Research (Nos. 16550038 and 19550041) from
the Ministry of Education, Culture, Sports, Science, and
Technology, Japan. The support of the Kitasato University
Research Grant for Young Researchers (to M. M.) is also
acknowledged.
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1594 | New J. Chem., 2009, 33, 1588–1595

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