How does non-covalent Se...Se=O interaction stabilize selenoxides at naphthalene 1,8-positions: Structural and theoretical investigations

Article abstract of DOI:10.1039/b809763a

Bis-selenides (LL), such as 8-[MeSe(X)]-1-[MeSe(Z)]C₁₀H ₆ (1 (LL)), 8-[EtSe(X)]-1-[EtSe(Z)]C₁₀H₆ (2 (LL)), 8-[p-YC₆H₄Se(X)]-1-[MeSe(Z)]C₁₀H ₆ (3 (LL)) and 8-[p-YC

Full text of DOI:10.1039/b809763a

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PAPER
www.rsc.org/njc | New Journal of Chemistry
How does non-covalent Seꢀ ꢀ ꢀSeQO interaction stabilize selenoxides at
naphthalene 1,8-positions: structural and theoretical investigationsw
Satoko Hayashi,a Waro Nakanishi,*a Atsushi Furuta,a Jozef Drabowicz,b
Takahiro Sasamoric and Norihiro Tokitohc
Received (in Montpellier, France) 9th June 2008, Accepted 25th September 2008
First published as an Advance Article on the web 17th November 2008
DOI: 10.1039/b809763a
Bis-selenides (LL), such as 8-[MeSe(X)]-1-[MeSe(Z)]C10H6 (1 (LL)), 8-[EtSe(X)]-1-[EtSe(Z)]C10H6
(2(LL)), 8-[p-YC6H4Se(X)]-1-[MeSe(Z)]C10H6 (3(LL)) and 8-[p-YC6H4Se(X)]-1-[p-YC6H4Se(Z)]C10H6
(4 (LL)) were oxidized with ozone at 0 1C, where (X, Z) = (lone pair, lone pair) for LL.
Bis-selenoxides, 1 (OO), 3 (OO) and 4 (OO) where (X, Z) = (oxygen, oxygen), were obtained in
the oxidation of 1 (LL), 3 (LL) and 4 (LL), respectively, via corresponding selenide-selenoxides,
1 (LO), 3 (LO) and 4 (LO), respectively. A facile Se–C bond cleavage was observed in 2 (LL).
The structures of 1 (LO) and 1 (OO) were determined by the X-ray analysis. Three Seꢀ ꢀ ꢀSeQO
atoms in 1 (LO) and four OQSeꢀ ꢀ ꢀSeQO atoms in 1 (OO) align linearly. While the non-covalent
Seꢀ ꢀ ꢀSeQO 3c–4e interaction operates to stabilize 1 (LO), the non-covalent OQSeꢀ ꢀ ꢀSeQO 4c–4e
interaction would not stabilize 1 (OO). The 3c–4e interaction must play an important role to
control the stereochemistry of selenoxides. The 8-G-1-[MeSe(OH)2]C10H6 (n (OHꢀOH)) are the key
intermediates in the racemization of 8-G-1-[MeSe(O)]C10H6 (n (O)) in solutions, where G = SeMe
(1), H (5), F (6), Cl (7) and Br (8). Energies of n (OHꢀOH), relative to n (O), are evaluated based
on the theoretical calculations. G of SeMe is demonstrated to operate most effectively to protect
from racemization of selenoxides among n = 1 and 5–8, since the relative energies
for G of cis- and trans-SeMe are largest.
der Waals radii minus 1 A.8,9 Various types of non-covalent
Introduction
interactions are detected in naphthalene 1,8-positions.8–11 The
Selonoxides1–4 [RSe(O)R0] afford optically active enantiomers,
as well as sulfoxides,5,6 if R and R0 are not the same, since Se
s-type three center-four electron interactions (s(3c–4e)),12–14
s(2c–4e),12 p(2c–4e),12 distorted p(2c–4e),12 and Z4 4c–6e13
are typical examples. Such non-covalent interactions are
in each selenoxide is three-coordinated containing a lone pair.
demonstrated to control the fine structures of molecules.15
However, it is usually difficult to utilize optical active selen-
oxides to introduce the optical activity in a target mole-
cule,1,2,4,7 since the racemization of optical active selenoxides
naphthalene with G = H, F, Cl and Br, together with
Recently, we investigated fine structures of 8-G-1-(arylseleninyl)-
is usually very fast. Nevertheless, some efforts have been made
the factors to control the structures, as the first step to
control the stereochemistry of selenoxides.16 The factors are
to stabilize the stereochemistry of selenoxides, by taking
advantage of non-covalent coordination by the neighboring
called G, O and Y dependences, which originate from the
groups (G) of the Gꢀ ꢀ ꢀSeQO type.2,4,7
np(G)ꢀ ꢀ ꢀs*(Se–O), np(O)ꢀ ꢀ ꢀp(Nap) and np(O)ꢀ ꢀ ꢀp(Ar) interac-
tions, respectively.16
We paid much attention to G = MeSe and ArSe in 8-G-1-
Naphthalene 1,8-positions supply a good system to investi-
gate such interactions, since the non-bonded distances between
heteroatoms at the positions are close to the sum of the van
(arylseleninyl)naphthalenes, since many conformers are plau-
sible around the two Se–CNap bonds, relative to the case of
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 8253
G = H and halogens. Scheme 1 shows the orbitals taking part
in the non-covalent Seꢀ ꢀ ꢀSeQO interaction. A bis-selenide
b Center of Molecular and Macromolecular Studies, Polish Academy
of Science, Sienkiewicza, 112, 90-363 Lodz, Poland
c Institute for Chemical Research, Kyoto University, Gokasho, Uji,
Kyoto 611-0011, Japan
w Electronic supplementary information (ESI) available: Energies and
relative energies for 8-G-1-[MeSe(X)]C10H6 [G = MeSe (1), H (5), F
(6), Cl (7) and Br (8) with X = lone pair (L), O (O), OH+ (OH+) and
O2H2 (OHꢀOH)], the packing structures of 1 (OO), counter map for
1 (OO), Cartesian coordinates for optimized structures of 1 and 5–8
with X = lone pair (L), O (O), OH+ (OH+) and O2H2 (OHꢀOH)].
CCDC reference numbers 688690 (1 (LO)) and 688691 (1 (OO)). For
ESI and crystallographic data in CIF or other electronic format see
DOI: 10.1039/b809763a
Scheme 1 Orbitals taking part in the non-bonded Seꢀ ꢀ ꢀSeQO inter-
actions in naphthalene 1,8-positions.
ꢁc
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performed on 8-G-1-[MeSe(X)]C10H6 [G = MeSe (1), H (5),
F (6), Cl (7) and Br (8) with X = lone pair (L), O (O), OH+
(OH+) and O2H2 (OHꢀOH)], where OHꢀOH must be the key
intermediate in the racemization of 1 and 5–8, in the presence
of a trace of water. The relative energy [DE = E(n (OHꢀOH))
ꢂ (E(n (O)) + E(H2O)) (n = 1 and 5–8)] is evaluated: that for
G = MeSe is largest among them. The larger value must
correspond to a selenoxide with the stronger resistance for
racemization, although n (OHꢀOH) is not the transition state.
The Gꢀ ꢀ ꢀSeQO interactions containing the Seꢀ ꢀ ꢀSeQO
and OQSeꢀ ꢀ ꢀSeQO interactions are also analyzed with the
natural orbital (NBO)19,20 and atoms-in-molecules (AIM)21,22
analyses.
Oxidation of 1,8-bis(selanyl)naphthalenes (LL) with ozone
is well controlled and monitored, which gives 1,8-bis(seleninyl)-
naphthalenes (OO) via 8-selanyl-1-seleninylnaphthalenes (LO).
Factors to control the fine structures of 1 (LO) and 1 (OO) are
clarified based on QC calculations, after determination of the
structures. The Seꢀ ꢀ ꢀSeQO interaction is demonstrated to
control the fine structure of 1 (LO), whereas the role of the
OQSeꢀ ꢀ ꢀSeQO interaction in 1 (OO) is critically discussed.
The role of G in 1 and 5–8 in the racemization process is also
evaluated.
Chart 1 Bis(selanyl)naphthalenes, 1–4, together with 5–8.
contains double ns(Se), np(Se), s(Se–C) and s*(Se–C) orbitals.
0
However, ns(O), np(O), np (O), s(Se–O) and s*(Se–O) appear
newly with the quit of an np(Se), when a selenide-selenoxide is
formed from the bis-selenide.
The oxidation and formation of 8-[2RSe(X)]-1-
2
2
[1RSe(Z)]C10H6 (1 (1R = R = Me), 2 (1R = R = Et), 3
(1R = Me, 2R = p-YC6H4: Y = H (a), MeO (b) and NO2 (d))
and 4 (1R = 2R = p-YC6H4: Y = H (a) and tBu (c)) are
investigated for LL where (X, Z) = (lone pair, lone pair), LO
(lone pair, oxygen) and OO (oxygen, oxygen) (Chart 1). The
reactions are easily controlled and each process is followed by
the spectroscopic method. Non-bonded OQSeꢀ ꢀ ꢀSeQO
interactions are also the subject of interest.
Results and discussion
Survey of oxidation
Bis-selenides (n (LL): n = 1–4) were oxidized with ozone in the
methylene dichloride solution of each bis-selenide at 0 1C. The
bis-selenides (n (LL)) gave corresponding bis-selenoxides
(n (O)) via corresponding selenide-selenoxides (n (LO)), except
for 2 (LL). While 1 (LL) gave 1 (LO), followed by the quanti-
tative formation of 1 (OO), a facile Se–C bond cleavage
occurred on the oxidation of 2 (LL), resulting in the formation
of naphtho-1,8-[c,d]-1,2-diselenole (9).23 b-Elimination of the
selenoxide may be responsible for the facile Se–C bond
cleavage. In the case of 3 (LL), the methylselanyl Se atoms
were attacked exclusively. 3 (LO) were consumed to produce
the corresponding 3 (OO) with more ozone. 4 (LO) were also
produced from the corresponding 4 (LL) with ozone, followed
by the formation of the corresponding 4 (OO), respectively.
The results are summarized in Chart 1. The reactions are well
followed by NMR.
The structures around the naphthyl group (Nap) in 8-G-1-
RSeC10H6 are well explained by three types, type A (A), B and
C.8c,d,f–h,17,18 The combined notation are used to specify the
structures of 1–4 with G = RSe, where the notation, such as
AA, BA or CA, shows the conformers around the two CNap–Se
bonds. Scheme 2 draws the notations employed in this work,
exemplified by 1 (LO).
The structures of 1 (LO) and 1 (OO) are determined by
X-ray crystallographic analysis. Quantum chemical (QC) cal-
culations are performed on 1 (LO) and 1 (OO), to elucidate the
role of the Seꢀ ꢀ ꢀSeQO interaction in 1 (LO) and the
OQSeꢀ ꢀ ꢀSeQO interaction in 1 (OO) as the factor to control
the fine structures. Orbitals of two Se atoms in 1 (LO) and
1 (OO) must overlap directly with each other, which would
stabilize the fine structures. QC calculations are also
Structures of 1 (LO) and 1 (OO)
Single crystals of 1 (LO) and 1 (OO) were obtained via slow
evaporation of methylene dichloride-hexane solutions and one
of suitable crystals was subjected to X-ray crystallographic
analysis for each compound.24 Only one type of structure
corresponds to each of 1 (LO) and 1 (OO) in the crystals.
Table 1 shows the crystallographic data of 1 (LO) and
1 (OO). Fig. 1 shows the structures of 1 (LO) and 1 (OO).25
The packing structure of 1 (OO) is shown in Fig. S1 of the
Electronic Supplementary Information (ESIw). Selected inter-
atomic distances, angles and torsional angles of the com-
pounds 1 (LO) and 1 (OO) are collected in Table 2, together
with those of 1 (LL), which contains two types, 1 (LL)A
and 1 (LL)B.26
Scheme 2 Structures around naphthyl group in 8-G-1-[RSe(X)]C10H6,
exemplified by 1 (LO).
ꢁc
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Table 1 Crystallographic data for 1 (LO) and 1 (OO)
1 (LO) 1 (OO)
interaction operates effectively to keep the Se–O bond on the
naphthyl plane in 1 (LO) (G dependence).16 These results show
that the structure of 1 (LO) is well stabilized by the O and G
dependences observed in 1-naphthyl selenoxides.16
Empirical formula
Formula weight
Temperature/K
Crystal system
Space group
a/A
C12H12OSe2 C12H12O2Se2ꢀ2.5H2O
330.14
298(2)
Monoclinic Monoclinic
391.18
103(2)
On the other hand, there is no np(Se) in 1 (OO). Therefore,
the G dependence of the np(Se)ꢀ ꢀ ꢀs*(Se–O) type cannot
operate in 1 (OO). Consequently, the driving force for the
structure must come from the O dependence for both Se–O
bonds. Namely, the non-covalent O–Seꢀ ꢀ ꢀSe–O s(4c–4e) in-
teraction must be carefully examined as a factor to stabilize the
fine structure of 1 (OO), although the non-bonded Seꢀ ꢀ ꢀSe
distances are less than the sum of van der Waals radii by
ca. 0.65 A.27 The s(4c–4e) interaction seems not so important.
How does G of MeSe control the fine structure and the
behavior? QC calculations are performed on 1 and 5–8.
P21/n (#14) C2/c (#15)
5.8460(19) 25.549(9)
14.473(3) 5.8653(18)
14.1490(16) 20.850(8)
b/A
c/A
b/1
97.660(17)
1186.5(5)
4
1.848
640
117.329(4)
2775.6(16)
8
1.872
1544
2435
V/A3
Z
Dc/g cmꢂ3
F(000)
Reflections observed [I 4 2s(I)] 2200
Parameters
R1 [I 4 2s(I)]
R1 [all data]
oR2 [I 4 2s(I)]
oR2 [all data]
Goodness-of-fit on F2
136
190
0.032
0.082
0.065
0.077
1.029
0.021
0.022
0.053
0.054
1.109
QC calculations
QC calculations were performed on 1 (LO) with the B3LYP/
6-311+G(d) method of the Gaussian 98 program.28–30 QC
calculations revealed energy profiles of the compounds.31
Table 3 collects the results of the QC calculations. The NBO
analysis19,20 were performed on 1 (LO) and 1 (OO) with the
B3LYP/6-311+G(d) method. The results are shown in
Table 4. The AIM parameters21,22 are calculated for 1 (LO)
and 1 (OO) with the Gaussian 03 program32 employing the
6-311+G(3df) basis sets for Se with the 6-311+G(3d,2p) basis
sets for C and H at the B3LYP level. They are analyzed
employing the AIM 2000 program.33 Table 5 collects the
results of AIM calculations.
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 solid
states and in solutions. Therefore, it must be instructive to
consider those predicted by QC calculations, although we
must be careful for the crystal packing effect in crystals and
the solvent effect in solutions, since such effects often larger
than the predicted factors.
The effect of G to stabilize 8-G-1-[MeSe(X)]C10H6 [G =
MeSe (1), H (5), F (6), Cl (7) and Br (8) with X = lone pair
(L), O (O), OH+ (OH+) and O2H2 (OHꢀOH)] will be dis-
cussed in detail, here. The results clarified the factors for the
racemization of selenoxides. n (OHꢀOH) (n = 1 and 5–8) must
be the key intermediates in the racemization of n (O), in the
presence of (a trace of) water in solutions.
Fig. 1 Structures of 1 (LO) (a) and 1 (OO) (b) with atomic numbering
scheme for selected atoms (thermal ellipsoids are shown at the 50%
probability level).
Effect of G in 1 and 5–8
Racemization of an optically active selenoxide is believed to
proceed via a selenide dihydroxide (n (OHꢀOH)).4a–d Scheme 3
shows a hypothetical racemization process of optically active
n (O*) via n (OHꢀOH).
The structures of 1 (LO) and 1 (OO) are all AA for two
methyl groups (Fig. 1 and Table 2).15 The planarity of the
naphthyl (Nap) planes is very good. All Se–O bonds are placed
in the naphthyl plane. The superior tendency of the Se–O
bonds to stay on the naphthyl plane (O dependence)16 must be
the driving force for the structures of 1 (LO) and 1 (OO). Three
Seꢀ ꢀ ꢀSe–O atoms align linearly (+SeSeO = 173.31(15)1) and
the Se–O bond is almost perpendicular to another CNapSeCMe
plane in 1 (LO). The non-covalent np(Se)ꢀ ꢀ ꢀs*(Se–O) 3c–4e
Protonation of n (O*) occurs at O of an optically active
isomer of n (O*: R) to give n (O*H+: R) at the initial stage of
the reaction. n (OHꢀOH) will form in the reaction of n (O*H+:
R) with water followed by the deprotonation to yield n (OHꢀ
OH). Elimination of water from n (OHꢀOH) results in the
racemization, since of n (OHꢀOH) is not optically active as a
whole. Similar reactions occur starting from n (O*: S) to yield
n (OHꢀOH) via n (O*H+: S), which also leads to racemization.
ꢁc
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Table 2 Selected interatomic distances (A), angles (1) and torsional angles (1) around Se atom in 1 (LO) and 1 (OO), together with those of 1 (LL)
a
a
1 (LL)A
1 (LL)B
1 (LO)
1 (OO)
Interatomic distances
Se1–Se2
Se1–C1
Se1–C11
Se1–O1
Se2–C9
Se2–C12
Se2–O2
3.051(4)
1.929(4)
1.944(4)
3.064(4)
1.932(3)
1.953(4)
3.1587(10)
3.1512(8)
1.983(5)
1.954(5)
1.653(4)
1.928(5)
1.938(6)
1.959(2)
1.940(2)
1.6771(15)
1.970(2)
1.934(2)
1.680(15)
1.926(4)
1.944(4)
1.932(4)
1.949(4)
Angles
Se2–Se1–C11
Se2–Se1–O1
Se1–Se2–C12
Se1–Se2–O2
Se1–C1–C10
C1–Se1–C11
C1–Se1–O1
C11–Se1–O1
Se2–C9–C10
C9–Se2–C12
C9–Se2–O2
C12–Se2–O2
C1–C10–C9
164.47(3)
150.34(3)
146.46(3)
159.73(3)
85.93(16)
173.31(15)
85.65(18)
88.26(7)
167.54(5)
89.41(7)
167.51(5)
124.33(16)
94.73(9)
102.69(8)
102.85(9)
124.67(16)
93.38(9)
102.21(8)
102.29(9)
128.1(2)
122.9(3)
99.29(16)
123.9(3)
98.41(16)
126.9(4)
96.0(2)
101.1(2)
100.7(2)
124.1(4)
98.1(2)
123.9(3)
99.27(16)
122.9(3)
98.50(16)
126.4(3)
127.2(3)
127.0(4)
Torsional angles
Se1–C1–C10–C5
C10–C1–Se1C11
C10–C1–Se1–O1
Se2–C9–C10–C5
C10–C9–Se2–C12
C10–C9–Se2–O2
O1–Se1–Se2–O2
173.5(2)
ꢂ154.1(3)
ꢂ176.0(2)
ꢂ177.6(4)
82.8(4)
ꢂ175.0(4)
178.8(4)
84.6(4)
179.19(15)
ꢂ86.49(19)
169.19(17)
178.90(15)
ꢂ87.10(19)
169.54(18)
140.3(3)
136.8(3)
172.2(2)
ꢂ138.8(3)
ꢂ170.2(2)
148.0(3)
a
Ref. 26.
Table 3 Energies and relative energies for 8-G-1-[MeSe(OiHj)]C10H6
(i, j = 0, 1 and 2)a
Table 4 Second order perturbation energies in the donor (D)–accep-
tor (A) interactions of the n(G)ꢀ ꢀ ꢀs*(Se–O) type in 8-G-1-[MeSe(O)]-
C10H6 and 8-G-1-[MeSe+(OH)]C10H6, calculated with the NBO
methodab
Form
O: A/AAb
OH+: A/AAb OHꢀOH: AC
5 (G = H)
Qn(Se)
Qn(O)
Qn(H)
+Wc
ꢂ2902.0303 ꢂ2902.4017
ꢂ2978.4686
D; A
np(G); s*(Se–O)
np(G): s*(Se+–OH)
1.309
ꢂ0.968
1.307
ꢂ0.837
1.324
ꢂ0.996, ꢂ0.993
0.433, 0.433
ꢂ2978.4686
G = F
G = Cl
G = Br
G = cis-SeMe
G = trans-SeMe
G = trans-SeMee
G = trans-Se(O)Mee
1.44
3.29
9.15 (0.87)c
13.65 (1.09)c
27.95 (1.19)c
34.99 (1.76)c
41.86 (2.69)c
0.497
ꢂ2978.4741 ꢂ2978.2198
3.73
Dd,e
as 0.0
667.7 (as 0.0) 14.4 (as 0.0)
4.77d
5.52
6 (G = F)
+Wc
ꢂ3001.3000 ꢂ3001.6744
ꢂ3077.7371
ꢂ3077.7371
ꢂ3077.7438 ꢂ3077.4925
5.86
1.53 (ꢃ2)f
Dd,e
7 (G = Cl)
as 0.0
ꢂ3361.6478 ꢂ3362.0250
ꢂ3438.0916 ꢂ3437.8431
659.8 (ꢂ7.9) 17.6 (3.2)
ꢂ3438.0833
ꢂ3438.0833
a
b
c
The 6-311+G(d) basis sets being employed. In kcal molꢂ1
.
Corres-
+Wc
d
ponding to the ns(G)ꢀ ꢀ ꢀs*(Se+–OH) interaction. 0.76 kcal molꢂ1 for
Dd,e
8 (G = Br)
as 0.0
ꢂ5475.5651 ꢂ5475.9442
ꢂ5552.0089 ꢂ5551.7623
652.4 (ꢂ15.2) 21.8 (7.4)
e
the ns(Se)ꢀ ꢀ ꢀs*(Se–O) type interaction. The 6-311+G(3df) basis sets
ꢂ5552.0007
ꢂ5552.0007
+Wc
being employed for Se with the 6-311+G(3d,2p) basis sets for C and
H. Corresponding to the ns(Se)ꢀ ꢀ ꢀs*(Se–O) interactions.
Dd,e
as 0.0
647.4 (ꢂ20.2) 21.5 (7.1)
f
1 (G = trans-MeSe) ꢂ5342.8896 ꢂ5343.2854
ꢂ5419.3241
ꢂ5419.3241
+Wc
ꢂ5419.3334 ꢂ5419.1035
Dd,e
1 (G = cis-MeSe)
as 0.0
ꢂ5342.8869 ꢂ5343.2821
ꢂ5419.3307 ꢂ5419.1002
603.6 (ꢂ64.1) 24.4 (10.0)
ꢂ5419.3214
ꢂ5419.3214
+Wc
Table 5 Second order perturbation energies in the donor–acceptor
interactions of the n(G)ꢀ ꢀ ꢀs*(Se–O) type at the naphthalene 1,8-
positions in 1 (LO) and 1 (OO), calculated with the NBO methoda
Dd,e
a
as 0.0f
612.3 (ꢂ55.4) 31.5 (17.1)
Calculated with the B3LYP/6-311+G(d) method. A for 5–8 and
b
c
ꢂ3
ꢂ5
AA for 1. Evaluated based on the values of E(H2O2) = ꢂ151.5891 au,
Compound ro(Se, Se)/A rb(rc)/eao
Drb(rc)/eao
Hb(rc)/au
E(H2O) = ꢂ76.4438 au and E(OHꢂ) = ꢂ75.8181 au calculated with
d
the same method. Relative to that of the corresponding n(O): A.
1 (LO)
1 (OO)
3.2521
3.2851
0.0195
0.0160
0.0420
0.0393
ꢂ0.0005
e
0.0002
Relative to the same structure derived from 5 (G = H) being
f
given in parenthesis. 7.1 kJ molꢂ1 from the corresponding species of
1 (G = trans-MeSe; O): AA.
a
The 6-311+G(3df) basis sets being employed for Se and the
6-311+G(3d,2p) basis sets for C and H.
ꢁc
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H2O2) ꢂ E(n (O) + H2O)) (see Table S1 in the ESIw). Simi-
larly, eqn (2) and (3) exhibit DE(n(OH+)) and DE(n(OHꢀOH)),35
respectively, which are defined as [E(n (OH+) + HOꢂ) ꢂ
E(n (O) + H2O)] and [E(n (OHꢀOH)) ꢂ E(n (O) + H2O)],
respectively.36
DE(n (LO)) = E(n (L) + H2O2) ꢂ E(n (O) + H2O)
G = H (121.8 kJ molꢂ1) o F (131.3) o cis-MeSe (133.9)
o Cl (136.8) r Br (137.6) o trans-MeSe (141.0)
(1)
DE(n (OH+)) = E(n (OH+) + HOꢂ) ꢂ E(n (O) + H2O)
G = H (667.7 kJ molꢂ1) 4 F (659.8) 4 Cl (652.4) 4 Br
(647.4) c cis-MeSe (605.2) 4 trans-MeSe (603.6)
(2)
Scheme 3 Mechanism for racemization of n(O*) via n(OHꢀOH) (n = 1
and 5–8).
DE(n (OHꢀOH)) = E(n (OHꢀOH)) ꢂ E(n (O) + H2O)
G = H (14.4 kJ molꢂ1) o F (17.6) o Cl (21.8) E Br (21.5)
Water may originate from the solvent and the racemization
would proceed under the neutral conditions. The stability of
n (OHꢀOH) must affect on the rates of racemization for the
optical active selenoxides.
o trans-MeSe (24.4) o cis-MeSe (31.5)
(3)
The order in eqn (1) corresponds the energy lowering effect
by the Gꢀ ꢀ ꢀSe–O interactions in the formation selenoxides
relative to the Gꢀ ꢀ ꢀSe–C interactions in selenides. However, we
must be careful to examine the values for G = cis-MeSe and
trans-MeSe, since the structure of the corresponding selenide is
commonly CC (see Table S1 in the ESIw).
Eqn (2) exhibits that the protonation on the seleninyl O
atom occurs more easily in the order of G = H o F o Cl o
Br { cis-MeSe o trans-MeSe. The results show that the
protonation occurs more easily when G become better donors,
especially for G = MeSe. The evaluated DE(n (OH+)) values
are very large in magnitudes, however, they do not mean that
the process is very difficult to occur. The large magnitudes are
the results of the calculations for the charge separated species
of the n (OH+) + HOꢂ type. Only the relative values are
important, since protonation will occur easily in solutions.
Resulting hypervalent np(G)ꢀ ꢀ ꢀs*(Se–OH+) interactions sta-
bilize further the species in the order shown in eqn (2), relative
to the case of the selenoxides.
The effect of G on the stability of 8-G-1-[MeSe(OiHj)]C10H6
[1 and 5–8: L (i = j = 0), O (i = 1, j = 0), OH+ (i = j = 1)
and OHꢀOH (i = j = 2)] are examined based on the QC
calculations. The results of QC calculations performed with
the B3LYP/6-311+G(d) method are collected in Table 3.
Table 3 also contains natural charges (Qn) of Se and O
calculated employing the natural population analysis.20
Scheme 4 shows optimized structures of the global minimum
for each of 1 (LL), 1 (LO) and 1 (LOH+), together with the
three types, AA0, BB and AC, for 1 (LOHꢀOH). The values for
AC of n (LOHꢀOH) are given in Table 3, since AC is most
stable among the three for each.34
Energy differences of the reactions in Scheme 3 are exam-
ined based on the values shown in Table 3. The energy of n(O) +
H2O (E(n (O) + H2O)) is taken as the standard for each, for
convenience of comparison. How are the selenoxides stabilized
by G at the 8-position? The effect of G on the stabilization of
selenoxides is examined before discussion the energy profile
shown in Scheme 3.
The activation energies for the racemization of optically
active selenoxides are closely related to the values shown in
eqn (3), although they are the energies for the intermediates,
n (OHꢀOH). The activation energies are expected to increase in
this order. The activation energy for G = cis-MeSe is pre-
dicted to be larger than that with trans-MeSe. However, cis-
MeSe and trans-MeSe isomers interconvert with each other.
Therefore, it may be better to evaluate the value by G = trans-
MeSe under the experimental conditions: The activation
energy of 1 (LO) with G = MeSe is estimated to be about
10 kJ molꢂ1 larger than that of 5 (L) with G = H and the
Eqn (1) shows the energies of n (L) + H2O2 (E(n (L) +
H2O2)) relative to E(n (O) + H2O) [DE(n (LO) = E(n (L) +
former is also larger than the case of G = Br by ca. 3 kJ molꢂ1
.
Fig. 2 summarizes the effect of G given in eqn (2).
G at the 8-position will protect sterically from the racemiza-
tion of an optical active n (O*). G must stabilize the optical
active n (O*) and the protonated n (O*H+) whereas G would
destabilize n (OHꢀOH). The steric congestion at the backside
of the Se+–OH bond in n (O*H+) by G will block the space
for H2O to attack to produce n (OHꢀOH) (Scheme 4). We must
be careful, since G could also stabilize n (OHꢀOH) in some
Scheme 4 Optimized structures for 1 (G = SeMe) and the deriva-
tives.
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Fig. 2 Energies of n (OHꢀOH), relative to n (O) for n = 1 and 5–8.
cases. The calculated values might correspond to the total
effects of the electronic and steric effects. Energy profiles for
the racemization evaluated by above calculations must contain
main factors. The energies for the transition states must be
close to those of the intermediates, n (OHꢀOH).
Fig. 4 Contour map of rb(rc) for 1 (LO) in the SeSeC9 plane, together
with BCPs ( ), ring critical points ( ) and bond paths. The contours
[eaoꢂ3] are at 2l (l = ꢄ8, ꢄ7,. . .0) and 0.0047 (heavy line). Two Me
groups are located upside and downside of the SeSeC9 plane. The C2,
C3, C6 and C7 atoms with the C–H bonds deviate substantially from
the plane.
NBO analysis for n(G)ꢀ ꢀ ꢀr*(Se–O) interactions
AIM analysis of 1 (LO) and 1 (OO)
Table 4 summarizes the second order perturbation energies
(E(2)) for the charge transfer (CT) interactions of the
n(G)ꢀ ꢀ ꢀs*(Se–O) type in 8-G-1-[MeSe(O)]C10H6 and 8-G-1-
[MeSe+(OH)]C10H6 evaluated with the NBO method.37 The
B3LYP/6-311+G(d) method is employed for the calculations.
The E(2) values becomes larger in an order shown in eqn (4).
The AIM analysis are carried out on 1 (LO) and 1 (OO). The
6-311+G(3df) basis sets are employed for Se and the
6-311+G(3d,2p) basis sets for C and H at the B3LYP level.
Table 5 collects the AIM parameters of 1 (LO) and 1 (OO) for
the bond critical points (BCPs: rc) on the interaction lines
between non-bonded Se atoms.
E(2): G = F (1.44) o Cl (3.29) o Br (3.73) o cis-MeSe
The low values of electron densities at BCPs (rb(rc)) in
1 (LO) and 1 (OO) (0.016–0.020 eaoꢂ3) show that the interac-
tions are ionic in nature. Laplacian values of rb(rc) (Drb(rc))
are both positive, whereas the total electron energy densities at
BCPs (Hb(rc)) for 1 (LO) is negative but it is positive for
1 (OO). The results strongly suggest that the np(G)ꢀ ꢀ ꢀs*(Se–O)
interaction in 1 (LO) is the CT interaction in nature similarly
to the case of R2Seꢀ ꢀ ꢀBr2 (MC) but the ns(G)ꢀ ꢀ ꢀs*(Se–O)
interactions in 1 (OO) seems weaker than such CT interac-
tions.40
(4.77) o trans-MeSe (5.52)
(4)
The E(2) values are also evaluated for 1 (LO) and 1 (OO),
employing the 6-311+G(3df) basis sets for Se and the
6-311+G(3d,2p) basis sets for C and H at the B3LYP level.38
Table 4 also contains the values. The np(G)ꢀ ꢀ ꢀs*(Se–O) inter-
action are evaluated to be 5.9 kcal molꢂ1 for 1 (LO)39 and as
1.5 (ꢃ 2) kcal molꢂ1 for the ns(G)ꢀ ꢀ ꢀs*(Se–O) interactions in
1 (OO). The larger value for 1 (LO) relative to 1 (OO) implies
the more effective interaction of the np(G)ꢀ ꢀ ꢀs*(Se–O) type in
1 (LO). The contribution of the 4c–4e interaction of the
O–Seꢀ ꢀ ꢀSe–O type was not detected by the NBO analysis.
Fig. 3 summarizes the interactions.
Fig. 4 shows the counter map of rb(rc) in the SeSeC9 plane
for 1 (LO), together with BCPs ( ), ring critical points ( ),
bond paths and the interaction lines. BCP are detected on the
2
Seꢀ ꢀ ꢀSe and Oꢀ ꢀ ꢀ H interaction lines. The BCP on the Seꢀ ꢀ ꢀSe
The nature of the np(G)ꢀ ꢀ ꢀs*(Se–O) interaction in 1 (LO)
and the ns(G)ꢀ ꢀ ꢀs*(Se–O) interactions in 1 (OO) are evaluated
based on the AIM analysis, next.
interaction line well visualize the np(Se)ꢀ ꢀ ꢀs*(Se–O) interac-
2
tion in 1 (LO). While BCP is also detected on the Oꢀ ꢀ ꢀ H
interaction line, the interaction is very small. A similar counter
map is also drawn for 1 (OO), which is shown in Fig. S2 of the
ESI.w
Conclusion
X-Ray crystallographic analysis of 8-methylselanyl-1-(methyl-
seleninyl)naphthalene (1 (LO)) and 1,8-bis(methylseleninyl)-
naphthalene 1 (OO) revealed that the three Seꢀ ꢀ ꢀSeQO
atoms in 1 (LO) and the four OQSeꢀ ꢀ ꢀSeQO atoms in
1 (OO) align linearly. All Se–O bonds are placed in the
naphthyl plane. The superior tendency for the Se–O bonds
to stay on the naphthyl plane (O dependence) must be the
Fig.
3
The np(G)ꢀ ꢀ ꢀs*(Se–O) interaction in 1 (LO) and the
ns(G)ꢀ ꢀ ꢀs*(Se–O) interactions in 1 (OO) evaluated by the NBO method.
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driving force for the fine structures of 1 (LO) and 1 (OO). The
noncovalent np(Se)ꢀ ꢀ ꢀs(Se–O) 3c–4e interactions (G depen-
dence) operate effectively to stabilize the structure of 1 (LO).
On the other hand, the driving force for the structure of 1 (OO)
must mainly come from the O dependence for each Se–O bond
in 1 (OO), since the G dependence cannot operate without
np(Se).
TMS): 13.3, 125.7, 128.3, 131.9, 132.3, 135.3, 135.6; 77Se NMR
(76 MHz, CDCl3, d, ppm, Me2Se): 231.4. Anal. Calc. for
1 (LL) (C12H12Se2): C, 45.88; H, 3.85%. Found: C, 45.73;
H, 3.77%.
8-Methylselanyl-1-(methylseleninyl)naphthalene
(1 (LO)).
1 (LL) (0.98 mg, 3.12 mmol) was dissolved in 20 mL of CH2Cl2
and the solution was bubbling with the ozone for 5 min. TLC
was checked for the completion of the reaction (rf = 0.07
(chloroform)). Then the solution was evaporated and dried
in vacuo. The crude product was purified by column chromato-
graphy (flash column, Al2O3, CH2Cl2). 1 (LO) gave 85% yield
as colorless powder, mp 129.8–130.1 1C; 1H NMR
(400 MHz, CDCl3, d, ppm, TMS): 2.29 (s, 3H), 2.78 (s, 3H),
7.48 (t, J 7.6 Hz, 2H), 7.76 (t, J 7.7 Hz, 2H), 7.98–8.05 (m, 2H),
8.10 (dd, J 1.1 and 7.2 Hz, 1H), 8.88 (dd, J 1.2 and 7.4 Hz,
1H); 13C NMR (75 MHz, CDCl3, d, ppm, TMS): 13.87, 41.12,
125.73, 126.28, 126.35, 126.57, 131.01, 132.44, 133.06, 136.13,
138.93, 141.34; 77Se NMR (76 MHz, CDCl3, d, ppm, Me2Se):
210.8, 833.0. Anal. Calc. for 1 (LO) (C12H12OSe2): C, 43.66; H,
3.66%. Found: C, 43.61; H, 3.60%.
QC calculations clarify the factors that protect from race-
mization of selenoxides. The energies of 8-G-1-[MeSe(OH)2]-
C10H6 from (8-G-1-[MeSe(O)]C10H6 + H2O) are shown to be
in an order of G = H (14.4 kJ molꢂ1) o F (17.6) o Cl (21.8)
E Br (21.5) o trans-SeMe (24.4) o cis-SeMe (31.5). The
activation energies for the racemization should increase in this
order, since 8-G-1-[MeSe(OH)2]C10H6 must be the key inter-
mediates. The activation energy of 1 (LO: G = MeSe) is
evaluated to be larger than that of 5 (L: G = H) and 8
(L: G = Br) by 10 and 3 kJ molꢂ1, respectively. The results
will help to design the optically stable selenoxides. The NBO
and AIM analyses support the discussion and visualize the
interactions.
Investigations on the chiral 3a (LO), prepared in the oxida-
tion of 3a (LL) with chiral reagents, are in progress. Details
will be reported elsewhere.
1,8-Bis(methylseleninyl)naphthalene (1 (OO)). 1 (LL) (0.58 g,
0.30 mmol) was dissolved in 20 mL of CH2Cl2 and the solution
was bubbling with the ozone for 15 min. TLC was checked for
the completion of the reaction (rf = 0.00 (chloroform)). Then
the solution was evaporated and dried in vacuo. The crude
product was purified by column chromatography (flash
column, Al2O3, CH2Cl2). 1 (OO) gave 59% yield as colorless
Experimental
General considerations
Manipulations were performed under an argon atmosphere
with standard vacuum-line techniques. Glassware was dried at
130 1C overnight. Solvents and reagents were purified by
standard procedures if necessary. Melting points were deter-
mined on a Yanaco MP-S3 melting point apparatus and
uncorrected. NMR spectra were recorded at room tempera-
ture on a JEOL AL-300 spectrometer (1H, 300 MHz; 13C,
75 MHz) and on a JEOL Lambda-400 spectrometer (1H, 400
MHz; 77Se, 76 MHz). The 1H, 13C and 77Se NMR spectra were
recorded in CDCl3. Chemical shifts are given in ppm relative
to Me4Si for the 1H and 13C NMR spectra and relative to
reference compound MeSeMe for the 77Se NMR spectra.
Column chromatography was performed by using silica gel
(Fujishilysia PSQ-100B) and basic alumina (E. Merck) and
analytical thin layer chromatography was performed on pre-
coated silica gel plates (60F-254) with the systems (v/v)
indicated.
1
powder, mp 154.8–155.2 1C; H NMR (400 MHz, CDCl3, d,
ppm, TMS): 2.71 (s, 6H), 7.84 (t, J 7.7 Hz, 2H), 8.18 (dd, J 1.2
and 6.9 Hz, 2H), 8.71 (dd, J 1.4 and 6.9 Hz, 2H); 77Se NMR
(76 MHz, CDCl3, d, ppm, Me2Se): 821.3. Anal. Calc. for
1 (OO) (C12H12O2Se2): C, 41.64; H, 3.49%. Found: C, 41.55;
H, 3.45%. Anal. Calc. for 1 (OO)ꢀ2.5H2O (C24H24O4Se4ꢀ
5H2O): C, 36.84; H, 4.38%. Found: C, 36.87; H, 4.41%.
1,8-Bis(ethylselanyl)naphthalene (2 (LL)). Following the
similar method to that used for 1 (LL), 2 (LL) gave 80% yield
1
as colorless powder, mp 52.3–52.8 1C; H NMR (400 MHz,
CDCl3, d, ppm, TMS): 1.35 (t, J 7.4 Hz, 6H), 2.89 (q, J 7.5 Hz,
4H), 7.32 (t, J 7.6 Hz, 2H), 7.70 (dd, J 1.2 and 8.1 Hz, 2H),
7.76 (dd, J 1.1 and 7.2 Hz, 2H); 77Se NMR (76 MHz, CDCl3,
d, ppm, Me2Se): 341.7. Anal. Calc. for 2 (LL) (C14H16Se2): C,
49.14; H, 4.71%. Found: C, 49.23; H, 4.72%.
8-Phenylselanyl-1-(methylseleninyl)naphthalene (3a (LO)).
Following the similar method to that used for 1 (LO),
3a (LO) gave 80% yield as colorless needles, mp 129.8–130.2
Syntheses
Bis(methylselanyl 1,8-bis(methylselanyl)naphthalene (1(LL)).
To a solution of the dianion of naphtho[1,8-c,d]-1,2-diselenole,
which was prepared by reduction of the diselenole 923 (1.03 g,
3.64 mmol) with NaBH4 in an aqueous THF solution, was
added methyl iodide (1.29 g, 9.06 mmol) at room temperature.
After a usual workup, the crude was purified by column
chromatography (flash column, SiO2, hexane). Recrystalli-
zation of the chromatographed product from hexane gave
1
1C; H NMR (400 MHz, CDCl3, d, ppm, TMS): 2.72 (s, 3H),
6.98–7.02 (m, 2H), 7.11–7.16 (m, 3H), 7.56 (t, J 7.6 Hz, 1H),
7.76 (t, J 7.7 Hz, 1H), 8.05 (dd, J 1.2 and 8.0 Hz, 1H), 8.10
(dd, J 1.3 and 8.1 Hz, 1H), 8.15 (dd, J 1.3 and 7.2 Hz, 1H),
8.82 (dd, J 1.3 and 7.3 Hz, 1H); 13C NMR (75 MHz, CDCl3, d,
ppm, TMS) 40.56, 123.19, 126.51, 126.57, 126.75, 126.88,
128.42 (2J(Se,C) 5.9 Hz), 129.63, 131.95, 132.42, 133.03,
133.50, 136.29, 140.89, 141.37; 77Se NMR (76 MHz, CDCl3,
d, ppm, Me2Se): 398.2, 831.4. Anal. Calc. for 3a (LO)
(C17H14OSe2): C, 52.06; H, 3.60%. Found: C, 52.11;
H, 3.66%.
1
1 (LL) as colorless prisms in 98% yield, mp 85.0–85.5 1C, H
NMR (300 MHz, CDCl3, d, ppm, TMS): 2.33 (s, 6H), 7.32 (t, 2H,
J = 7.7 Hz), 7.70 (dd, 2H, J = 1.2 and 8.2 Hz), 7.73 (dd, 2H,
J = 1.2 and 7.5 Hz); 13C NMR (75 MHz, CDCl3, d, ppm,
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8-Phenylseleninyl-1-(methylseleninyl)naphthalene (3a (OO)).
Following the similar method to that used for 1 (OO),
3a (OO) gave 63% yield as colorless needles, mp 148.0–148.8 1C;
1H NMR (400 MHz, CDCl3, d, ppm, TMS): 2.74 (s, 3H),
7.33–7.50 (m, 3H), 7.51–7.58 (m, 2H), 7.78 (t, J 7.7 Hz, 1H),
7.81 (t, J 7.7 Hz, 1H), 8.13 (dd, J 1.1 and 8.1 Hz, 1H), 8.14 (dd,
J 1.1 and 8.1 Hz, 1H), 8.63 (dd, J 1.4 and 7.4 Hz, 1H), 8.72
(dd, J 1.3 and 7.3 Hz, 1H); 13C NMR (75 MHz, CDCl3, d,
ppm, TMS): 38.25, 126.72, 126.80, 126.85, 127.01, 127.64,
127.92, 130.02, 131.70, 133.33, 133.71, 135.55, 138.88,
139.22, 141.66; 77Se NMR (76 MHz, CDCl3, d, ppm, Me2Se):
820.0, 832.5. Anal. Calc. for 3a (OO) (C17H14O2Se2): C, 50.02;
H, 3.46%. Found: C, 50.07; H, 3.57%.
dissolved in 100 mL of dry THF and the solution was added to
nBuLi (15.0 mL, 23.94 mmol, 1.6 N) at ꢂ78 1C. After 20 min,
a THF solution of phenylselenobromide (22.80 mmol) was
added to the above solution at ꢂ78 1C. Then the reaction
mixture was stirring for 2 h and warmed up room temperature.
Then, 20 mL of 5% acetone hydrochloric acid and 100 mL of
benzene were added. The organic layer was separated, washed
with brine, 10% aqueous solution of sodium hydroxide,
saturated aqueous solution of sodium bicarbonate and brine.
Then the solution was dried over sodium sulfate, evaporated
and dried in vacuo. The crude product was purified by column
chromatography (flash column, SiO2, hexane). 4a (LL) gave
89% yield as yellow prisms, mp 64.0–64.8 1C; 1H NMR
(300 MHz, CDCl3, d, ppm, TMS): 7.22–7.28 (m, 8H),
7.39–7.45 (m, 4H), 7.64 (dd, J 1.1 and 7.3 Hz, 2H), 7.74
(dd, J 1.1 and 8.3 Hz, 2H); 13C NMR (75 MHz, CDCl3,
d, ppm, TMS): 126.0, 127.4, 129.2, 129.4, 131.4, 133.4, 135.18,
135.19, 135.5, 135.9; 77Se NMR (76 MHz, CDCl3, d, ppm,
Me2Se): 435.4. Anal. Calc. for 4a (LL) (C22H16Se2): C, 60.29;
H, 3.68%. Found: C, 60.21; H, 3.75%.
8-p-Anisylselanyl-1-(methylseleninyl)naphthalene (3b (LO)).
Following the similar method to that used for 1 (LO),
3b (LO) gave 88% yield as colorless needles, mp 129.6–130.4 1C;
1H NMR (400 MHz, CDCl3, d, ppm, TMS): 2.70 (s, 3H),
3.82 (s, 3H), 6.70 (d, J 8.8 Hz, 2H), 7.01 (d, J 8.8 Hz, 2H), 7.51
(t, J 7.2 Hz, 1H), 7.74 (t, J 7.2 Hz, 1H), 7.88 (dd, J 1.1 and
6.8 Hz, 1H), 8.01 (dd, J 1.1 and 6.8 Hz, 1H), 8.03 (dd, J 1.1
and 6.8 Hz, 1H), 8.10 (dd, J 1.1 and 6.8 Hz, 1H); 77Se NMR
(76 MHz, CDCl3, d, ppm, Me2Se): 385.9, 833.9. Anal. Calc.
for 3b (LO) (C18H16O2Se2): C, 51.20; H, 3.82%. Found: C,
50.98; H, 3.83%.
8-Phenylselanyl-1-(phenylseleninyl)naphthalene
(4a (LO)).
Following the similar method to that used for 1 (LO),
4a (LO) gave 65% yield as colorless prisms, mp 155.5–156.3 1C;
1H NMR (400 MHz, CDCl3, d, ppm, TMS): 6.90–6.95
(m, 4H), 7.10–7.13 (m, 6H), 7.22–7.26 (m, 6H), 7.48–7.53
(m, 4H), 7.52 (t, J 8.2 Hz, 1H), 7.83 (d, J 7.7 Hz, 1H), 8.07
(dd, J 1.3 and 7.2 Hz, 1H), 8.08 (dd, J 1.3 and 8.2 Hz, 1H), 9.02
(dd, J 1.3 and 7.3 Hz, 1H); 13C NMR (75 MHz, CDCl3, d, ppm,
TMS): 123.90, 126.45, 126.51, 126.79, 127.86, 127.91, 128.70,
129.17, 129.49, 130.11, 131.73, 132.76, 133.27, 133.78, 136.31,
140.17, 140.71, 146.21; 77Se NMR (76 MHz, CDCl3, d, ppm,
Me2Se): 400.1, 863.7. Anal. Calc. for 4a (LO) (C22H16OSe2):
C, 58.17; H, 3.55%. Found: C, 58.11; H, 3.65%.
8-p-Anisylseleninyl-1-(methylseleninyl)naphthalene
(3b (OO)). Following the similar method to that used for
1 (OO), 3b (OO) gave 43% yield as colorless powder, mp
1
144.5–145.0 1C; H NMR (400 MHz, CDCl3, d, ppm, TMS):
2.75 (s, 3H), 3.76 (s, 3H), 6.87 (d, J 8.9 Hz, 2H), 7.45 (d, J 8.9
Hz, 2H), 7.83 (t, J 7.7 Hz, 2H), 8.15 (dd, J 1.0, 8.2 Hz, 1H),
8.17 (dd, J 1.0, 8.2 Hz, 1H), 8.69 (dd, J 1.3, 9.1 Hz, 1H), 8.71
(dd, J 1.2, 9.1 Hz, 1H); 77Se NMR (76 MHz, CDCl3, d, ppm,
Me2Se): 821.6, 846.4. Anal. Calc. for 3b (OO) (C18H16O3Se2):
C, 49.33; H, 3.68%. Found: C, 49.30; H, 3.73%.
1,8-Bis(phenylseleninyl)naphthalene (4a (OO)). Following
the similar method to that used for 1 (OO), 4a (OO) gave
8-p-Nitrophenylselanyl-1-(methylseleninyl)naphthalene
(3d (LO)). Following the similar method to that used for
1 (LO), 3d (LO) gave 61% yield as colorless powder, mp
1
78% yield as colorless prisms, mp. 187.5–188.3 1C; H NMR
(400 MHz, CDCl3, d, ppm, TMS): 7.21–7.30 (m, 8H), 7.37 (tt,
J 1.5 and 6.8 Hz, 2H), 7.76 (t, J 7.7 Hz, 2H), 8.15 (dd, J 0.9 and
7.5 Hz, 2H), 8.47 (dd, J 1.1 and 6.2 Hz, 2H); 77Se NMR
(76 MHz, CDCl3, d, ppm, Me2Se): 877.1. Anal. Calc. for
4a (OO) (C22H16O2Se2): C, 56.19; H, 3.43%. Found: C, 56.22;
H, 3.53%.
1
141.5–142.0 1C; H NMR (400 MHz, CDCl3, d, ppm, TMS):
2.67 (s, 3H), 7.07 (dt, J 2.1 and 9.0 Hz, 2H), 7.64 (t, J 7.5 Hz,
1H), 7.83 (t, J 7.5 Hz, 1H), 7.99 (dt, J 2.4 and 9.0 Hz, 2H), 8.11
(dd, J 1.2 and 6.9 Hz, 2H), 8.18 (dd, J 1.2 and 4.2 Hz, 1H),
8.21 (dd, J 1.5 and 4.8 Hz, 1H), 8.84 (dd, J 1.2 and 6.0 Hz,
1H); 77Se NMR (76 MHz, CDCl3, d, ppm, Me2Se): 426.4,
835.6. Anal. Calc. for 3d (LO) (C17H13NO3Se2): C, 46.70; H,
3.00; N, 3.20%. Found: C, 46.75; H, 3.03; N, 3.22%.
1,8-Bis[(p-tert-butylphenyl)selanyl]naphthalene
(4c (LL)).
Following the similar method to that used for 4a (LL),
4c (LL) gave 87% yield as yellow prisms, mp 97.8–98.3 1C;
1H NMR (400 MHz, CDCl3, d, ppm, TMS): 1.30 (s 18H), 7.24
(t, J 7.7 Hz, 2H), 7.27 (d, J 8.6 Hz, 4H), 7.38 (d, J 8.6 Hz, 4H),
7.65 (dd, J 1.3 and 6.1 Hz, 2H), 7.73 (dd, J 1.3 and 7.0 Hz,
2H); 77Se NMR (76 MHz, CDCl3, d, ppm, Me2Se): 424.6.
Anal. Calc. for 4c (LL) (C30H32Se2): C, 65.45; H, 5.86%.
Found: C, 65.41; H, 5.88%.
8-p-Nitrophenylseleninyl-1-(methylseleninyl)naphthalene
(3d (OO)). Following the similar method to that used for
1 (OO), 3d (OO) gave 82% yield as colorless powder, mp
1
151.2–152.0 1C; H NMR (400 MHz, CDCl3, d, ppm, TMS):
2.83 (s, 3H), 7.72–7.92 (m, 4H), 8.12–8.27 (m, 4H), 8.57 (dd,
J 1.1 and 6.2 Hz, 1H), 8.74 (dd, J 1.3 and 6.1 Hz, 1H); 77Se
NMR (76 MHz, CDCl3, d, ppm, Me2Se): 821.4, 849.0. Anal.
Calc. for 3d (OO) (C17H13NO4Se2): C, 45.05; H, 2.89; N,
3.09%. Found: C, 45.12; H, 2.83; N, 3.12%.
8-[(p-tert-Butylphenyl)selanyl]-1-[(p-tert-butylphenyl)seleninyl]-
naphthalene (4c (LO)). Following the similar method to that
used for 1 (LO), 4c (LO) gave 86% yield as colorless powder,
mp 179.5–180.2 1C; 1H NMR (400 MHz, CDCl3, d,
ppm, TMS): 1.22 (s, 9H), 1.27 (s 9H), 6.91 (d, J 8.3 Hz, 2H),
1,8-Bis(phenylselanyl)naphthalene (4a (LL)). Under an argon
atmosphere, 1,8-diiodonaphthalene (4.33 g, 11.40 mmol) was
ꢁc
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7.15 (d, J 8.1 Hz, 2H), 7.28 (d, J 8.8 Hz, 2H), 7.43 (d, J 8.6 Hz,
2H), 7.51 (t, J 7.9 Hz, 1H), 7.82 (t, J 7.7 Hz, 1H), 8.07 (d, J 8.3
Hz, 3H), 9.01 (dd, J 1.3 and 7.5 Hz, 1H); 77Se NMR (76 MHz,
CDCl3, d, ppm, Me2Se): 393.2, 861.2. Anal. Calc. for 4c (LO)
(C30H32OSe2): C, 63.61; H, 5.69%. Found: C, 63.55;
H, 5.58%.
program.27 Calculations are performed at the density func-
tional theory (DFT) level of the Becke three parameter hybrid
functionals combined with the Lee-Yang-Parr correlation
functional (B3LYP).28,29 QC calculations are also performed
on 8-G-1-[MeSe(X)]C10H6 [G = MeSe (1), H (5), F (6), Cl (7)
and Br (8) with X = lone pair (L), O (O), OH+ (OH+) and
O2H2 (OHꢀOH)], employing the B3LYP/6-311+G(d) method.
The NBO19,20 analysis were performed with the B3LYP/
6-311+G(d) method. The AIM21,22 analysis are performed on
1 (LO) and 1 (OO) with the Gaussian 03 program employing the
6-311+G(3df) basis sets for Se with the 6-311+G(3d,2p) basis
sets for C and H at the B3LYP level. They are analyzed
employing the AIM 2000 program.21,22 NBO analysis are also
performed on 1 (LO) and 1 (OO) with the same method for the
AIM analysis. Optimized structures and the molecular orbitals
are drawn using MolStudio R3.2 (Rev 1.0).43
1,8-Bis[(p-tert-butylphenyl)seleninyl]naphthalene (4c (OO)).
Following the similar method to that used for 1 (OO),
4c (OO) gave 87% yield as colorless powder, mp 172.5–173.2 1C;
1H NMR (400 MHz, CDCl3, d, ppm, TMS): 1.63 (s, 18H),
7.39 (d, J 8.6 Hz, 4H), 7.47 (d, J 8.3 Hz, 4H), 7.83 (d, J 7.6 Hz,
2H), 8.16 (dd, J 0.8 and 7.3 Hz, 2H), 8.73 (dd, J 1.0 and 6.2
Hz, 2H); 77Se NMR (76 MHz, CDCl3, d, ppm, Me2Se): 843.7.
Anal. Calc. for 4c (OO) (C30H32O2Se2): C, 61.86; H, 5.54%.
Found: C, 61.93; H, 5.58%.
1-(Methylselanyl)naphthalene (5 (L)). Following the similar
method to that used for 1 (LL), 5 (L) gave 99% yield as pale
Acknowledgements
1
yellow oil; H NMR (400 MHz, CDCl3, d, ppm, TMS): 2.37
(s, JSe,H 11.7 Hz, 3H), 7.35 (dd, J 7.3 and 8.1 Hz, 1H), 7.47
This work was partially supported by a Grant-in-Aid for
Scientific Research (Nos. 16550038, 19550041 and 20550042)
from the Ministry of Education, Culture, Sports, Science and
Technology, Japan.
2
(ddd, J 1.6, 6.9 and 8.2 Hz, 1H), 7.53 (ddd, J 1.6, 6.9 and 8.3
Hz, 1H), 7.66 (dd, J 1.1 and 7.3 Hz, 1H), 7.71 (d, J 8.2 Hz,
1H), 7.80 (dd, J 1.7 and 7.9 Hz, 1H), 8.24 (ddd, J 0.7, 1.6 and
8.1 Hz, 1H); 13C NMR (75 MHz, CDCl3, d, ppm, TMS):
36.54, 122.08 (J 14.9 Hz), 124.03 (J 6.2 Hz), 126.11, 126.79,
127.56, 129.35, 130.27, 131.40, 133.88, 138.68; 77Se NMR
(76 MHz, CDCl3, d, ppm, Me2Se): 158.6. Anal. Calc. for 5 (L)
(C11H10Se): C, 59.74; H, 4.56%. Found: C, 59.90; H, 4.49%.
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CDCl3, d, ppm, TMS): 2.71 (s, JSe,H 12.3 Hz, 3H),
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X-Ray crystal structure determination. The colorless crystals
of 1 (LO) and 1 (OO) were grown by slow evaporation of
methylene dichloride-hexane solutions at room temperature.
A crystal of 1 (LO) was measured on a Rigaku AFC5R
diffractometer with graphite monochromated Mo-Ka radia-
tion source (l = 0.71069 A) and a rotating anode generator at
298(2) K. That of 1 (OO) was measured on a Rigaku/MSC
Mercury CCD diffractometer equipped with a graphite-mono-
chromated Mo-Ka radiation source (l = 0.71070 A) at 103(2) K.
The structures of 1 (LO) and 1 (OO) were solved by direct
method (SHELXS-97)41 and refined by full-matrix least-
square method on F2 for all reflections (SHELXL-97).42 All
the non-hydrogen atoms were refined anisotropically.
QC calculations
QC calculations are performed on 1 (LO) and 1 (OO), as the
models of n (LO) and n (OO) (n = 1, 3 and 4), respectively,
employing the 6-311+G(d) basis sets of the Gaussian 98
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24 The structures of 3b (LO) and 3a (OO) are also determined by the
X-ray crystallographic analysis. The results are essentially the same
as those of 1 (LO) and 1 (OO), respectively, which will be reported
elsewhere.
25 Water molecules in 1 (OO) are omitted for clarity.
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14 For the 3c–4e treatment of the CT complexes, see: W. Nakanishi,
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18 The structure is A if the Se–CAr bond is placed almost perpendi-
cular to the naphthyl plane, it is B when the bond is located on the
plane and C is the intermediate between A and B.
19 A. E. Reed, R. B. Weinstock and F. Weinhold, J. Chem. Phys.,
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33 The AIM2000 program (Version 2.0) is employed to analyze and
visualize atoms in molecules: F. J. Biegler-Konig, Comput. Chem.,
¨
2000, 21, 1040–1048; see also ref. 22g.
34 Data for A and B, together with LL, are given in the ESIw.
35 The type C of 1 (OHꢀOH) is discussed which is predicted to be most
stable among the three44
.
20 E. D. Glendening, A. E. Reed, J. E. Carpenter and F. Weinhold,
NBO Ver. 3.1.
36 Eqn (R1) shows the energies of n (L) + H2O2 (E(n (L) + H2O2))
relative to E(n (O) + H2O) [DE(n (LO)) = E(n (L) + H2O2) ꢂ
E(n (O) + H2O)], although E(n (L)) are not given in Table 3.45
21 Atoms in Molecules. A Quantum Theory, ed. R. F. W. Bader, Oxford
University Press, Oxford, 1990; The Quantum Theory of Atoms in
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DE(n (LO)) = E(n (L) + H2O2) ꢂ E(n (O) + H2O)
G = H (121.8 kJ molꢂ1) o F (131.3) o cis-MeSe (133.9)
o Cl (136.8) r Br (137.6) o trans-MeSe (141.0)
(R1)
37 NOB analysis were also performed on the AC conformer of 8-G-1-
[MeSe(O2H2)]C10H6. However, the corresponding CT interactions
were not detected.
7314–7323; (d) F. Biegler-Konig, R. F. W. Bader and T. H. Tang,
¨
J. Comput. Chem., 1982, 3, 317–328; (e) R. F. W. Bader, Acc.
ꢁc
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38 The nonbonded Seꢀ ꢀ ꢀSe distance in 1 (LO) is predicted to be
shorter than that of 1 (OO) by ca. 0.03 A, while the observed
values are almost equal (see Table 5). The crystal packing effect
might contribute to the results.
39 The value is very close to that evaluated with the B3LYP/
6-311+G(d) method.
44 Three structures (type A, type B and type C) were optimized
for each of n (OHꢀOH). The type C is the global minimum,
which is slightly stable than type B and much stable than
type A, although the steric repulsion between OH and G seems
largest.
45 Eqn (R1)36 shows that selenoxides are stabilized in this order
through the non-bonded n(G)ꢀ ꢀ ꢀs*(Se–O) 3c–4e interactions,
together with the O dependence.16 While G = trans-MeSe is
demonstrated to be most effective to stabilize in the selenoxide
relative to the corresponding bis-selenide, the effect of G = cis-
MeSe places between F and Cl, where the CC form is postulated
for the bis-selenide.
40 W. Nakanishi, S. Hayashi and K. Narahara, unpublished results.
41 G. M. Sheldrick, SHELXS-97, Program for Crystal Structure
Solution, Universitat Gottingen, Germany, 1997.
¨
42 G. M. Sheldrick, SHELXL-97, Program for Crystal Structure
¨
Refinement, University of Gottingen, Germany, 1997.
¨
43 MolStudio R3.2 (Rev 1.0), NEC Corporation, 1997–2003.
ꢁc
This journal is The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2009
206 | New J. Chem., 2009, 33, 196–206