Synthesis and structure of a 1-phospha-2-boraacenaphthene derivative and its chalcogenation reactions

Article abstract of DOI:10.1002/chem.201304644

The first stable 1-phospha-2-boraacenaphthene 1 was synthesized by the reduction of 1-dimesitylboryl-8-dichlorophosphinonaphthalene (2 a) with elemental magnesium, and it was fully characterized. The chalcogenation reaction of 1 with elemental sulfur or selenium afforded the unique heterocycles, 2-thia- and 2-selena-1-phospha-3-boraphenalenes 9 S and 9 Se, respectively, through the insertion of the chalcogen atom into a P-B bond of 1. Further chalcogenation of 9 afforded the corresponding phosphine chalcogenides. These newly obtained chalcogenated compounds have been characterized. The unique dynamic behavior of 2-chalcogena-1-phospha-3-boraphenalene-1-chalcogenides 10 in solution has also been described.

Full text of DOI:10.1002/chem.201304644

DOI: 10.1002/chem.201304644
Full Paper
&
Heterocycles
Synthesis and Structure of a 1-Phospha-2-boraacenaphthene
Derivative and Its Chalcogenation Reactions
Akihiro Tsurusaki, Takahiro Sasamori,* and Norihiro Tokitoh*[a]
Dedicated to Emeritus Professor Renji Okazaki on the occasion of his 77th birthday
Abstract: The first stable 1-phospha-2-boraacenaphthene
1 was synthesized by the reduction of 1-dimesitylboryl-8-di-
chlorophosphinonaphthalene (2a) with elemental magnesi-
um, and it was fully characterized. The chalcogenation reac-
tion of 1 with elemental sulfur or selenium afforded the
unique heterocycles, 2-thia- and 2-selena-1-phospha-3-bora-
phenalenes 9S and 9Se, respectively, through the insertion
of the chalcogen atom into a PꢀB bond of 1. Further chalco-
genation of 9 afforded the corresponding phosphine chalco-
genides. These newly obtained chalcogenated compounds
have been characterized. The unique dynamic behavior of 2-
chalcogena-1-phospha-3-boraphenalene-1-chalcogenides 10
in solution has also been described.
tions.[8] On the basis of the previous reports on the chalcoge-
nation reactions of phosphinoborane derivatives shown in
Scheme 1,[7c,9] the chalcogenation reaction of 1 would be ex-
pected to afford unique heterocyclic compounds containing
a P(Ch)ꢀChꢀB (Ch=S, Se) moiety. Thus, we have examined the
sulfurization and selenization reactions of 1 in the expectation
of synthesis of new heterocyclic compounds containing P, B,
and chalcogen atoms.
Introduction
There has been broad interest in the chemistry of phosphine
borane (R3PꢀBR3) bearing a PꢀB coordinate bond especially
from the viewpoint of frustrated Lewis pairs (FLPs) in recent
years.[1] In particular, those with a forcedly connected PꢀB co-
ordinate bond in a rigid linker such as a 1,8-naphthalene skele-
ton are of great interest because they would be appropriate
model compounds for investigating the static nature of the Pꢀ
B coordinate bonds.[2] On the other hand, there seem to be
less examples of investigation of a PꢀB bond in a phosphino-
borane (R2PꢀBR2) probably due to the difficulty in the isolation
of a stable phosphinoborane,[3] though a phosphinoborane
would be a promisingly attractive species as a candidate for
unique chemical and physical properties.[3,4] Indeed, kinetic or
thermodynamic stabilization should be necessary to isolate
monomeric phosphinoborane as a stable compound, since
a
phosphinoborane undergoes facile oligomerization in
a head-to-tail manner with forming intermolecular PꢀB dative
bonds.[3,5] A series of kinetically stabilized phosphinoboranes
bearing mesityl, phenyl, trimethylsilyl, and 1-adamantyl groups
have been reported by Power et al.,[6] whereas phosphinobor-
anes thermodynamically stabilized by coordination of a Lewis
acid and base, [(LA)H2PꢀBH2(LB)]) (LA=Lewis acid, LB=Lewis
base), have been reported by Scheer et al.[7] We report here
the synthesis and properties of 1-phospha-2-boraacenaph-
thene 1, which is a unique heterocyclic compound bearing
a PꢀB bond tethered with a naphthyl unit at the 1,8-posi-
Scheme 1. Examples of chalcogenation reactions of phosphinoboranes.
Results and Discussion
Diarylboryl-8-dichlorophosphinonaphthalenes 2a,b were pre-
pared from 1,8-dibromonaphthalene in two steps.[8] The X-ray
crystallographic analyses of 2a,b (Figure 1a and b) showed the
longer PꢀB distance of 2a (2.892(2), 2.961(2) ꢀ) than that of
2b (2.108(2) ꢀ), suggesting negligible intramolecular PꢀB coor-
dination in 2a due to the steric congestion in contrast to the
concrete PꢀB coordinate bond in 2b. Thus, it should be noted
that the boron atom of 2a surrounded by mesityl (Mes)
groups should be more congested than that of 2b bearing
two 3,5-di-tert-butylphenyl (Dtp) groups. In the 11B NMR spec-
[a] Dr. A. Tsurusaki, Prof. Dr. T. Sasamori, Prof. Dr. N. Tokitoh
Institute for Chemical Research, Kyoto University
Gakasho, Uji, Kyoto 611-0011 (Japan)
Fax: (+81)774-38-3200
E-mail: sasamori@boc.kuicr.kyoto-u.ac.jp
tokitoh@boc.kuicr.kyoto-u.ac.jp
Chem. Eur. J. 2014, 20, 3752 – 3758
3752
ꢁ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Full Paper
crystals isolated in 91% yield.[8] Thus, sterically demanding sub-
stituents on the PꢀB moiety should be of importance in the
stability of the 1-phospha-2-boraacenaphthene. The formation
of 1 by the reduction of dichlorophosphine 2a is most likely
interpreted in terms of the intermediacy of phosphinidenoid 4,
which would undergo facile isomerization giving 1 through
the intramolecular aryl migration from boron to phosphorus
(Scheme 2). Thus, it would be expected that this synthetic ap-
proach should be generally applicable toward synthesis of a 1-
phospha-2-boraacenaphthene from a 1-diarylboryl-8-dichloro-
phosphinonaphthalene when the boron atom has two sterical-
ly demanding aryl groups.
The monomeric molecular structure of 1 was definitively de-
termined by using X-ray crystallographic analysis (Figure 1c).[8]
Although the boron atom is located on the same plane of the
naphthalene skeleton, the phosphorus atom deviates from the
plane by about 0.36 ꢀ, in which the boron and phosphorus
atoms exhibit the planar and pyramidal geometries, respective-
ly. The PꢀB bond length of 1 is 1.889(3) ꢀ, which is slightly
longer than those in Mes2PBMes2 (6; 1.839(8) ꢀ) and Ph2PBMes2
(7; 1.859(3) ꢀ),[6] but apparently shorter than those of 2a,b,
suggesting the existence of a considerably strong PꢀB s-bond
in 1. Combined consideration of the PꢀB bond length and the
pyramidalization of the P atom in 1 suggests its negligible >
P(+)=B(ꢀ) < double-bond character. In the 11B NMR spectrum of
the C6D6 solution of 1, a broad signal was observed at dB =
77.9 ppm (Dn1/2 =1400 Hz), which is similar to those of 6 (dB =
82.4 ppm) and 7 (dB =70.9 ppm),[6] suggesting the trigonal-
planar geometry around the boron atom in solution. In the
31P NMR spectrum, the C6D6 solution of 1 exhibit the relatively
upper-field-shifted signal at dP =ꢀ28.2 ppm as compared with
those of 6 (dP =27.4 ppm) and 7 (dP =26.7 ppm),[6] probably
because of its different geometry of the phosphorus atom due
to steric reasons.
Figure 1. Molecular structures of a) 1-diarylboryl-8-dichlorophosphinonaph-
thalenes 2a, b) 2b, and c) 1-phospha-2-boraacenaphthene 1 (thermal ellip-
soids with 50% probability). All hydrogen atoms were omitted for clarity.
a) Two independent molecules of 2a were found in the unit cell. Selected
distances [ꢀ]: a) 2a: P1ꢀB1, 2.892(2), P1ꢀCl1, 2.0581(7), P1ꢀCl2, 2.0886(7),
P2ꢀB2, 2.961(2), P2ꢀCl3, 2.1083(7), P2ꢀCl4, 2.0562(7). b) 2b: PꢀB, 2.108(2),
PꢀCl1, 2.0112(8), PꢀCl2, 2.0408(7). c) 1: PꢀB, 1.889(3).
tra in C6D6, the contrastive signals of 2a and 2b were observed
as a highly broadened signal (Dv1/2 =1570 Hz) at d=63.9 ppm
of 2a and a relatively sharp signal (Dv1/2 =750 Hz) at d=
10.1 ppm of 2b, suggesting that their structural features in so-
lution are similar to those observed in the crystalline state. Re-
duction of less hindered phosphineborane 2b with magnesi-
um metal in THF solution at room temperature gave a mixture
of two isomers, (E)-3 and (Z)-3, dimers of the corresponding 1-
phospha-2-boraacenaphthene 5, isolated in 35 and 53% yields,
respectively (Scheme 2).[10] Therefore, the introduction of Dtp
groups should not be suitable for the isolation of a 1-phospha-
2-boraacenaphthene as a monomeric form. On the other hand,
reduction of 2a with magnesium metal under the same condi-
tions afforded 1-phospha-2-boraacenaphthene 1 as orange
Phosphaboraacenaphthene 1 was stable under inert condi-
tions even on heating of the C6D6 solution in a sealed tube at
1008C for 24 h. However, addition of degassed water into the
C6D6 solution of 1 afforded 1-hydroxy(mesityl)boryl-8-mesityl-
phosphinonaphthalene (8) in 93% yield (Scheme 3), suggest-
ing that the PꢀB bond exhibits enough reactivity towards
small molecules. On the other hand, theoretical calculations of
1 revealed the highest occupied molecular orbital (HOMO) of
1 exhibited a dominant contribution of lone-pair n-orbital of
the phosphorus atom, indicating that the lone-pair n-orbital of
the phosphorus atom can be reactive. Finally, as shown in
Scheme 1, the previous reports on the chalcogenation reac-
tions of stable phosphinoboranes resulting in the formation of
the corresponding phosphine-chalcogenides incorporated with
a heterocyclic system prompted us to examine the chalcoge-
nation reactions of the obtained 1-phospha-2-boraacenaph-
thene 1.
Chalcogenation reactions of 1-phospha-2-boraacenaphthene
1 are summarized in Scheme 3. All chalcogenation reactions
described below have been performed in a degassed and
sealed tube. Sulfurization reaction of 1 with S8 (2 equiv as S) in
C6D6 at 1008C for 40 h resulted in the formation of 2-thia-1-
phospha-3-boraphenalene-1-sulfide 10SS in 88% yield. Thus,
Scheme 2. Synthesis of 1-phospha-2-boraacenaphthene 1.
Chem. Eur. J. 2014, 20, 3752 – 3758
www.chemeurj.org
3753
ꢁ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Full Paper
Interestingly, selenization reaction of the PꢀSꢀB compound
(9S) with 1.5 equiv of Se in C6D6 at 1008C for 24 h resulted in
the formation of a mixed-chalcogen system of 2-thia-1-phos-
pha-3-boraphenalene-1-selenide 10SSe in 82% yield. Thus, iso-
lation of the mono-sulfurized compound of 9S gave us an op-
portunity to synthesize such unique mixed-chalcogen systems.
However, sulfurization of the PꢀSeꢀB compound (9Se) with S8
afforded no expected compound of 2-selena-1-phospha-3-bor-
aphenalene-1-sulfide 10SeS. When 9Se was treated with S8
(1 equiv as S) in C6D6 at 808C for 19 h and then at 1008C for 5
days, the 1H NMR spectrum of the reaction mixture showed
that all of the starting material had been consumed and 10SS,
10SeSe, and 10SSe were unexpectedly formed in the ratio of
3:2:10 in the 1H NMR spectrum. At the initial stage of the sulfu-
rization reaction of 9Se, signals for 9S and 10SeSe were ob-
served along with those for the starting material (9Se) as
1
judged by the H NMR spectra, indicating the facile chalcogen-
exchange reaction of 9Se giving 9S under these conditions
(Figure 2).
Scheme 3. Reactions of 1-phospha-2-boraacenaphthene 1. [a] P(NMe2)3
(2.5 equiv), C6D6, 608C, 3 h, 87%. [b] S8 (1 equiv as S), C6D6, 1008C, 9 h,
quant. [c] Se (1.5 equiv), C6D6, 1008C, 24 h, 82%. [d] Se (1.5 equiv), C6D6,
1008C, 3.5 days, 80%.
the sulfurization of 1 was found to afford the new heterocyclic
compound of 10SS bearing a P(S)ꢀSꢀB moiety as expected. At
this stage, we wonder which sulfur atom would firstly be intro-
duced onto the 1-phospha-2-boraacenaphthene skeleton.
Treatment of 1 with 1 equiv of elemental sulfur (S8) in C6D6 at
RT for 17 h gave a mixture of 1, 2-thia-1-phospha-3-boraphena-
lene 9S, and 2-thia-1-phospha-3-boraphenalene-1-sulfide 10SS
1
in a ratio of 4:3:1 as judged by the H and 31P NMR spectra, in-
dicating the intermediacy of 9S in the sulfurization of 1 giving
10SS. It was difficult to purify the reaction mixture of 1, 9S,
and 10SS by using general methods of purification such as
column chromatography or GPC due to their instability under
these purification conditions. Finally, it was found that the de-
sulfurization reaction of 10SS by P(NMe2)3 exclusively gave 9S,
which could be purified by recrystallization from toluene/
hexane and isolated in 87% yield. Treatment of S8 (1 equiv as
S) in C6D6 at 1008C for 9 h was found to afford 10SS quantita-
tively.
Figure 2. Molecular structures of a) 9S, b) 9Se, c) 10SS, and d) 10SSe (ther-
mal ellipsoids with 50% probability). All hydrogen atoms were omitted for
clarity. Selected bond lengths [ꢀ] and angles [8]: a) 9S: PꢀS, 2.1204(11), SꢀB,
1.802(4), P-S-B, 105.64(12); b) 9Se: PꢀSe, 2.2607(10), SeꢀB, 1.938(4), P-Se-B,
101.52(13); c) 10SS: Two independent molecules were found in the unit
cell: P1ꢀS1, 2.1125(10), S1ꢀB1, 1.814(3), P1ꢀS2, 1.9524(9), P1-S1-B1,
In contrast to the case of the sulfurization reaction described
above, heating of C6D6 solution of 1 with elemental selenium
at 508C for four days afforded 2-selena-1-phospha-3-boraphe-
nalene 9Se isolated exclusively in 81% yield. It should be
noted that compounds 9S and 9Se are the first examples of
the new heterocycles with phosphorus, boron, and chalcogen
atoms in the phenalene backbone.[11] A further selenization re-
action of 9Se with 1.5 equiv of Se in C6D6 at 1008C for
3.5 days resulted in the formation of 2-selena-1-phospha-3-bor-
aphenalene-1-selenide 10SeSe in 80% yield. Alternatively,
long-term heating of C6D6 solution of 1 with elemental seleni-
um at 1008C for five days directly gave 10SeSe isolated in
54% yield.
102.51(11), P2ꢀS3, 2.0948(10), S3ꢀB2, 1.808(3), P2ꢀS4, 1.9514(10), P2-S3-B2,
103.49(11). d) 10SSe: Two independent molecules were found in the unit
cell: P1ꢀS1, 2.1112(8), S1ꢀB1, 1.817(3), P1ꢀSe1, 2.1056(6), P1-S1-B1, 102.15(9),
P2ꢀS2, 2.0970(8), S2ꢀB2, 1.799(3), P2ꢀSe2, 2.1051(6), P2-S2-B2, 103.00(9).
The molecular structures of all of the newly obtained com-
pounds, 9S, 9Se, 10SS, 10SSe, and 10SeSe, have been unam-
biguously determined by X-ray crystallographic analyses. All re-
sults of the analyses supported their structures with reasonable
structural parameters. During the investigation on the molecu-
Chem. Eur. J. 2014, 20, 3752 – 3758
www.chemeurj.org
3754
ꢁ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Full Paper
lar structure of 10SeSe, interesting phenomena were found. In
particular, the two different kinds of crystals of 10SeSe were
obtained depending on the conditions of the crystal growth.
The single crystals obtained by the recrystallization from its tol-
uene/hexane solution at RT was found to exhibit the molecular
structure as 10SeSe with the P(Se)ꢀSeꢀB moiety as expected.
On the other hand, unexpectedly, the recrystallization from its
toluene solution at RT afforded the single crystals exhibiting
the structure of 10’SeSe with the P(m-Se2)B moiety. Unfortu-
nately, the detailed structural parameters could not be dis-
cussed with appropriate accuracy, because of the inevitable
severe 1:1 disorder with a pseudo-C2 axis. However, the theo-
retically optimized structural parameters for 10’SeSe at
B3PW91/6-311+G(3d)[6-31G(d) for C,H] level were in good
agreement with those experimentally observed, supporting
the reasonable solution of the X-ray data.[12] Anyway, there
should be no concrete chemical bond between the P and B
atoms in 10’SeSe because the observed distance (ca. 2.7 ꢀ)
between the P and B atoms was longer than those in the pre-
viously reported phosphine boranes. Theoretical calculations
on 10SeSe and 10’SeSe suggested the relative energy of
10’SeSe would be only +2.9 kcalmolꢀ1 (self-consistent field
(SCF), at B3PW91/6-311+G(3d)[6-31G(d) for C,H]) as compared
with 10SeSe, indicating that the difference of the structures in
the crystalline state would be simply due to the crystal packing
force (Figure 3).
Scheme 4. Intramolecular chalcogen exchange in 10ChCh.
Table 1. NMR spectral data for 1, 9S, 9Se, 10SS, 10SSe, and 10SeSe.[a]
Compound
1
9S
65.1
1110
ꢀ4.2
9Se
70.6
1050
ꢀ18.1
150.0
178
10SS
65.6
1190
37.5
10SSe 10SeSe
65.9 68.6
dB [ppm]
Dv1/2(dB) [Hz]
dP [ppm]
dSe [ppm]
JPSe [Hz]
77.9
1400
ꢀ28.2
1130 1100
19.7
ꢀ16.6
779
2.0
226.2[b]
539
–
–
–
–
[a] In C6D6 at RT. [b] Measured at 608C.
has two independent selenium atoms, the 77Se NMR spectrum
of 10SeSe in C6D6 shows only a broadened signal at RT and
one doublet signal coupled with the neighboring phosphorus
1
atom at 608C. The observed j JPSe j coupling constant (539 Hz)
is considerably larger than that of 9Se (150 Hz) and similar to
that of [Ph2PSe2Li·THF·TMEDA] (1JPSe =578 Hz; TMEDA=tetra-
methylethylenediamine),[13] in which the p-electrons would be
delocalized on the PSe2 moiety as a P(m-Se2)Li species. There-
fore, 10SeSe could be considered to exhibit the structure as
10’SeSe with a P(m-Se2)B moiety in solution, in which signals
for two selenium nuclei appeared equivalently in the 77Se NMR
spectrum. However, the structure of 10’SeSe cannot explain
The isolation of crystals of 10’SeSe naturally induced us to
consider the dynamic behavior of compound 10 in solution as
shown in Scheme 4. The NMR spectral data for 9 and 10 were
summarized in Table 1. Although one can think that 10SeSe
its 1) broadened 11B NMR signal (dB =68.6 ppm, Dv1/2
=
1100 Hz) indicating the three-coordinated boron atom, 2) rela-
tively upper-field 31P chemical shift (dP =2.0 ppm), and 3) con-
siderably lower-field 77Se NMR chemical shift (dSe =226 ppm).
As compared with the dB, dP, and dSe chemical shifts of 9Se
(dB =70.6, dP =ꢀ18.1, and dSe =150.0 ppm), those of 10SeSe
are similar in dB, and lower field in dP and dSe, suggesting elec-
tron deficiency in the P and Se atoms in 10SeSe. Thus, it can
be concluded that the facile exchange of the two selenium
atoms would occur in solution, exhibiting the dynamic behav-
ior between 10SeSe and 10’SeSe, in which the structure as
10SeSe bearing P(Se)ꢀSeꢀB moiety should be the dominant
contributor of the dynamic behavior along with the smaller
contribution of 10’SeSe bearing the P(m-Se2)B moiety. The dy-
namic behavior could not be perturbed even at ꢀ608C on the
basis of NMR spectra in toluene. It should be noted that the IR
spectrum of the single crystal of 10SeSe (KBr pellet), not those
of 10’SeSe, was almost identical that of the CCl4 solution of
10SeSe, suggesting the dominant contribution of 10SeSe in
solution, whereas the theoretically simulated IR spectra of
10SeSe and 10’SeSe seem to be somewhat different and that
of 10SeSe (calculated) is in good agreement with that ob-
Figure 3. Molecular structures of a) 10SeSe and b) 10’SeSe (thermal ellip-
soids with 50% probability). All hydrogen atoms were omitted for clarity. Se-
lected bond lengths [ꢀ] and angles [8]: a) 10SeSe: Two independent mole-
cules were found in the unit cell: P1ꢀSe1, 2.2526(8), Se1ꢀB1, 1.943(3), P1ꢀ
Se2, 2.1084(8), P1-Se1-B1, 98.05(10), P2ꢀSe3, 2.2314(8), Se3ꢀB2, 1.922(3), P2ꢀ
Se4, 2.1071(8), P2-Se3-B2, 99.72(11). b) 10’SeSe: Crystallographic pseudo-C2
axis passes through the center of the molecule: Definitive structural parame-
ters could not be obtained due to the severe disorder with pseudo-C2 sym-
metry. Obtained structural parameters: PꢀSe1, 2.139(6), Se1ꢀB, 2.30(3), Pꢀ
Se1*, 2.117(6), Se1*ꢀB, 2.33(3) ꢀ; P-Se1-B, 75.9(7), P-Se1*-B, 75.6(7), Se1-B-
Se1*, 87.9(10), Se1-P-Se1*, 98.2(2)8.
1
served. The H NMR spectra also suggested such facile chalco-
gen exchange in 10SeSe in solution. In both cases of 9S and
9Se, the six methyl groups of the two mesityl groups were ob-
served independently at room temperature in 1H NMR spec-
Chem. Eur. J. 2014, 20, 3752 – 3758
www.chemeurj.org
3755
ꢁ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Full Paper
mirror (for [D6]benzene) or phosphorus pentoxide (for CCl4), re-
trum in C6D6, suggesting the restricted rotation of the PꢀMes
and BꢀMes bonds. However, the ortho-methyl groups of each
Mes group of 10SeSe were observed equivalently in the
1H NMR spectrum, suggesting an averaged 10’SeSe structure
in solution through fast exchange of the two selenium atoms.
Similar to the case of 10SeSe, the ortho-methyl groups of
each Mes group of 10SS also gave an equivalent signal, indi-
cating a dynamic behavior similar to that of 10SeSe. In the
case of 10SSe, its ortho-methyl groups of each Mes group
were independently observed, but this gives no information
on the facile exchange of S and Se, because even its averaged
structure of 10’SSe would afford the independent signals for
the ortho-methyl groups. Although the 31P NMR chemical shift
of 10SS (dP =37.5 ppm) and 10SSe (dP =19.7 ppm) would be
somewhat shifted to lower field than that of 10SeSe, we be-
lieve facile chalcogen exchange would occur in all cases of
10SS, 10SSe, and 10SeSe. The IR spectra of 10SS, 10SSe, and
10SeSe are similar to each other and those theoretically simu-
lated as expected. Thus, the observed dynamic behavior of
10ChCh species would be specific feature in the P(Ch)ꢀChB
skeleton.
1
spectively. The H NMR (600 MHz) and 13C NMR (150 MHz) spectra
were measured in C6D6 with a BRUKER AVANCE III-600 spectrome-
1
ter. Signals due to C6D5H (d=7.15 ppm) in H NMR and those due
to C6D6 (d=128.0 ppm) in 13C NMR were used as internal referen-
ces, respectively. The 31P NMR (121 MHz), 11B NMR (95 MHz), and
77Se NMR (57 MHz) spectra were measured in C6D6 with a JEOL AL-
300 spectrometer using 85% H3PO4 in water (0 ppm), BF3·OEt2
(0 ppm), and Ph2Se2 (460 ppm) as an external standard, respective-
ly. Multiplicity of signals in 13C NMR was determined by DEPT,
HSQC, and HMBC techniques. High-resolution mass spectral data
were obtained on a JEOL JMS-700 spectrometer (EI and FAB). Infra-
red spectra were recorded as KBr pellets using a JASCO FT/IR-460
Plus spectrometer. All melting points were determined on
a Yanaco micro melting point apparatus and were uncorrected. El-
emental analyses were carried out at the Microanalytical Laborato-
ry of the Institute for Chemical Research, Kyoto University.
Reagents
Elemental selenium (Wako chemical) was used as received. Hexam-
ethylphosphosrus triamide were distilled from molecular sieve 4 A
prior to use. Elemental sulfur was recrystallized from benzene in
the dark. 1,2-Dimesityl-1-phoapha-2-boraacenaphthene (1) was
prepared according to the reported procedure.[8]
Conclusion
Syntheses
1-Phospha-2-boraacenaphthene 1 has been successfully syn-
thesized by the unique reaction of the reduction of 2a with el-
emental magnesium, and its structural features have been re-
vealed. Chalcogenation reactions of 1 gave the unique hetero-
cycles, 2-chalcogena-1-phospha-3-boraphenalenes 9S and
9Se, which have a PꢀChꢀB moiety tethered to the naphtha-
lene skeleton. Further chalcogenation reaction of 9 gave the
corresponding phosphine chalcogenides 10. Compounds 9
and 10 are the first examples of the new heterocycles with
phosphorus, boron, and chalcogen atoms in the phenalene
backbone. These compounds are fully characterized by spec-
troscopic and X-ray crystallographic analyses. In particular, the
dynamic behavior of 10SeSe was found in solution, in which
the two selenium atoms underwent facile exchange with each
other through the intermediate of 10’SeSe bearing a P(m-Se2)B
four-membered ring system. Interestingly, two kinds of single
crystals of 10SeSe and 10’SeSe were isolated depending on
the recrystallization conditions. Thus, it can be conceivable
that the related compounds, 10ChCh, would undergo similar
facile chalcogenation-exchange. These fundamental studies on
the chalcogenation reactions of 1 will be helpful for the under-
standing of the chalcogenation of phosphinoborane and the
creation of the unique heterocyclic systems containing several
heteroatoms by utilizing a PꢀB bond.
Treatment of 1 with elemental sulfur (2 equiv): A solution of
1 (122 mg, 0.300 mmol) in C6D6 (1 mL) and elemental sulfur
(19.2 mg, 0.600 mmol as S) was charged into an NMR tube with J-
1
Young valve. The reaction was monitored by H and 31P NMR spec-
troscopy. After heating at 1008C for 40 h, the solvent was removed
under reduced pressure. The residue was recrystallized from its tol-
uene/hexane solution at ꢀ408C to afford 1,3-dihydro-1,3-dimesityl-
2-thia-1-phospha-3-boraphenalene-1-sulfide
(10SS,
124 mg,
0.263 mmol, 88%) as yellow crystals. 10SS: yellow crystals. M.p.
1978C (decomp.). 1H NMR (600 MHz, C6D6, RT): d=1.89 (s, 3H,
MesP-p-Me), 2.04 (s, 6H, MesB-o-Me), 2.18 (s, 3H, MesB-p-Me), 2.40
(brs, 6H, MesP-o-Me), 6.47 (d, 4JHP =4.6 Hz, 2H, MesP-m-arom-CH),
3
6.74 (s, 2H, MesB-m-arom-CH), 6.95 (dd, JHH =8.2, 7.0 Hz, 1H, Phen-
3
4
5), 7.10 (ddd, JHH =8.1, 7.3 Hz, JHP =2.5 Hz, 1H, Phen-8), 7.48 (ddd,
3JHH =8.1 Hz, 4JHH =1.3 Hz, 4JHP =1.3 Hz, 1H, Phen-7), 7.55 (ddd,
4
4
3
3JHH =8.2 Hz, JHH =1.5 Hz, JHP =1.5 Hz, 1H, Phen-6), 7.91 (dd, JHH
=
7.0 Hz, 4JHH =1.5 Hz, 1H, Phen-4), 8.65 ppm (ddd, 3JHP =18.7 Hz,
3JHH =7.3 Hz, 4JHH =1.3 Hz, 1H, Phen-9); 13C NMR (150 MHz, C6D6,
RT): d=20.59 (d, 5JCP =1.3 Hz, MesP-p-CH3), 21.23 (MesB-p-CH3),
22.25 (MesB-o-CH3), 24.42 (d, 3JCP =5.2 Hz, MesP-o-CH3), 126.15 (d,
3JCP =15.7 Hz, Phen-8), 126.22 (Phen-5), 127.98 (MesB-m-arom-CH),
130.40 (br, Phen-3a), 131.14 (d, 1JCP =82.7 Hz, MesP-ipso-arom-CH),
3
4
132.11 (d, JCP =12.3 Hz, MesP-m-arom-CH), 133.29 (d, JCP =3.4 Hz,
3
1
Phen-7), 133.57 (d, JCP =8.9 Hz, Phen-6a), 134.05 (d, JCP =80.0 Hz,
2
2
Phen-9a), 134.12 (d, JCP =7.3 Hz, Phen-9b), 135.39 (d, JCP =12.9 Hz,
Phen-9), 136.35 (d, 4JCP =1.2 Hz, Phen-6), 138.28 (MesB-p-arom),
138.42 (MesB-o-arom), 138.76 (br, MesB-ipso-arom), 141.10 (d, JCP
=
4
3.0 Hz, MesP-p-arom), 141.59 (Phen-4), 142.30 ppm (d, JCP =11.6 Hz,
2
MesP-o-arom); 11B NMR (95 MHz, C6D6, RT): d=65.6 ppm (Dv1/2
=
=
1190 Hz); 31P NMR (121 MHz, C6D6, RT): d=37.5 ppm (d, JPH
3
Experimental Section
18.6 Hz); HRMS (FAB) m/z: 470.1466 [M]+; elemental analysis calcd
(%) for C28H2811BPS2 (470.1463): C 71.49, H 6.00; found: C 71.47, H
6.16.
General
All experiments were performed under an argon atmosphere
unless otherwise noted. Solvents used for the reactions were puri-
fied by an Ultimate Solvent System (Glass Contour Company).[14]
Solvents used in the spectroscopy were dried by using a potassium
Treatment of 10SS with hexamethylphosphosrus triamide: A
C6D6 solution (0.8 mL) of 10SS (94.1 mg, 0.200 mmol) and P(NMe2)3
(91 mL, 0.50 mmol) was degassed and sealed in an NMR tube. The
Chem. Eur. J. 2014, 20, 3752 – 3758
www.chemeurj.org
3756
ꢁ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Full Paper
reaction was monitored by 1H and 31P NMR spectroscopy. After
heating at 608C for 3 h, the volatile of the reaction mixture was re-
moved under reduced pressure. The residue was washed with
hexane, followed by recrystallization from its toluene/hexane solu-
tion to afford 1,3-dihydro-1,3-dimesityl-2-thia-1-phospha-3-bora-
phenalene (9S, 76.2 mg, 0.173 mmol, 87%) as yellow crystals. 9S:
(57 MHz, C6D6, RT): d=150.0 ppm (d, 1JPSe =178 Hz); HRMS (FAB)
m/z: 486.1204 [M]+; elemental analysis calcd (%) for C28H2811BP80Se
(486.1187): C 69.30, H 5.82; found: C 69.08, H 5.96.
Treatment of 1 with elemental selenium (2.0 equiv): A C6D6 solu-
tion (0.8 mL) of 1 (32.5 mg, 80.0 mmol) and elemental selenium
(12.6 mg, 160 mmol) was charged into an NMR tube with J-Young
1
M.p. 2188C (decomp.). H NMR (600 MHz, C6D6, RT): d=2.04 (s, 3H,
1
valve. The reaction was monitored by H and 31P NMR spectrosco-
MesP-p-Me), 2.16 (s, 3H, MesB-o-Me), 2.22 (s, 3H, MesB-p-Me), 2.47
(s, 3H, MesB-o-Me), 2.58 (br s, 6H, MesP-o-Me), 6.72–6.73 (m, 2H,
MesP-m-arom CH), 6.78–6.79 (m, 1H, MesB-m-arom CH), 6.86–6.87
py. After heating at 1008C for 5 days, compounds 10SeSe and 9Se
1
were obtained in the ratio of 9:2 as judged by the H NMR spectra.
The reaction mixture was filtered with benzene and then the sol-
vent of the filtrate was removed under reduced pressure. The resi-
due was reprecipitated from its benzene/hexane solution to afford
1,3-dihydro-1,3-dimesityl-2-selena-1-phospha-3-boraphenalene-1-
selenide (10SeSe, 24.6 mg, 43.6 mmol, 54%) as a sole product.
3
4
(m, 1H, MesB-m-arom CH), 6.93 (ddd, JHH =8.0, 7.3 Hz, JHP =2.3 Hz,
3
1H, Phen-8), 7.00 (dd, JHH =8.3, 7.0 Hz, 1H, Phen-5), 7.36–7.40 (m,
2H, Phen-7 and Phen-9), 7.57 (dd, 3JHH =8.3 Hz, 4JHH =1.4 Hz, 1H,
Phen-6), 7.86 ppm (ddd, 3JHH =7.0 Hz, 4JHH =1.4 Hz, 5JHP =1.4 Hz,
1H, Phen-4); 13C NMR (150 MHz, C6D6, 258C): d=21.03 (MesP-p-
CH3), 21.27 (MesB-p-CH3), 22.33 (MesB-o-CH3), 22.54 (MesB-o-CH3),
23.27 (br, MesP-o-CH3), 125.48 (d, 3JCP =4.9 Hz, Phen-8-CH), 126.22
(d, 5JCP =1.1 Hz, Phen-5-CH), 127.84 (MesB-m-arom-CH), 128.20
(MesB-m-arom-CH), 129.17 (d, 4JCP =3.5 Hz, Phen-7-CH), 129.45 (d,
2JCP =30.5 Hz, Phen-9-CH), 129.5 (br, MesP-m-arom-CH), 131.8 (br,
1
10SeSe: yellow crystals. M.p. 2058C (decomp.); H NMR (600 MHz,
C6D6, RT): d=1.85 (s, 3H, MesP-p-Me), 1.90 (s, 6H, MesB-o-Me), 2.17
(s, 3H, MesB-p-Me), 2.24 (s, 6H, MesP-o-Me), 6.35 (d, 4JHP =4.7 Hz,
2H, MesP-m-arom CH), 6.72 (s, 2H, MesB-m-arom CH), 6.89 (dd,
3JHH =8.0, 7.0 Hz, 1H, Phen-5), 7.13–7.16 (m, 1H, Phen-8), 7.46 (ddd,
3JHH =8.1 Hz, 4JHH =1.6 Hz, 4JHP =1.6 Hz, 1H, Phen-7), 7.54 (ddd,
1
MesP-m-arom-CH), 131.92 (d, JCP =40.0 Hz, MesP-ipso-arom), 132.74
4
4
3
3JHH =8.0 Hz, JHH =1.6 Hz, JHP =1.6 Hz, 1H, Phen-6), 7.86 (dd, JHH
=
(br, Phen-3a), 134.80 (Phen-6a), 135.43 (d, 2JCP =8.9 Hz, Phen-9b),
7.0 Hz, 4JHH =1.5 Hz, 1H, Phen-4), 9.21 ppm (dd, 3JHP =20.0 Hz,
3JHH =7.3 Hz, 4JHH =1.3 Hz, 1H, Phen-9); 13C NMR (150 MHz, C6D6,
RT): d=20.45 (d, 5JCP =1.5 Hz, MesP-p-CH3), 21.18 (MesB-p-CH3),
22.25 (MesB-o-CH3), 23.95 (d, 3JCP =5.8 Hz, MesP-o-CH3), 126.028
4
1
135.97 (d, JCP =2.0 Hz, Phen-6-CH), 135.98 (d, JCP =40.0 Hz, Phen-
9a), 137.59 (MesB-p-arom), 137.81 (MesB-o-arom), 138.77 (d, JCP
=
4
2.6 Hz, Phen-4-CH), 139.12 (MesB-o-arom), 140.56 (br, MesB-ipso-
arom), 141.02 (d, 4JCP =1.0 Hz, MesP-p-arom), 145.72 ppm (MesP-o-
arom); 11B NMR (95 MHz, C6D6, RT): d=65.1 ppm (Dv1/2 =1110 Hz);
31P NMR (121 MHz, C6D6, RT): d=ꢀ4.2 ppm (d, JPH =8.4 Hz); HRMS
(FAB) m/z: 438.1753 [M]+; elemental analysis calcd (%) for
C28H2811BPS (438.1742): C 76.72, H 6.44; found: C 76.66, H 6.45.
3
(Phen-5), 126.035 (d, JCP =15.8 Hz, Phen-8), 128.08 (MesB-m-arom-
1
1
CH), 131.13 (d, JCP =66.5 Hz, MesP-ipso-arom-CH), 131.15 (d, JCP
=
61.1 Hz, Phen-9a), 131.72 (d, 3JCP =11.8 Hz, MesP-m-arom-CH),
132.73 (br, Phen-3a), 133.80 (d, 3JCP =8.5 Hz, Phen-6a), 133.85 (d,
4JCP =3.5 Hz, Phen-7), 134.90 (d, 2JCP =7.3 Hz, Phen-9b), 136.33 (d,
Phen-6), 137.84 (MesB-o-arom), 138.23 (MesB-p-arom), 138.50 (d,
Treatment of 1 with elemental selenium (1 equiv): A C6D6 solu-
tion (0.8 mL) of 1 (32.5 mg, 80.0 mmol) and elemental selenium
(6.3 mg, 80 mmol) was charged into an NMR tube with J-Young
2JCP =14.4 Hz, Phen-9), 139.22 (br, MesB-ipso-arom), 140.59 (d, JCP
=
4
3.1 Hz, MesP-p-arom), 140.77 (Phen-4), 141.40 (d, 2JCP =11.2 Hz,
MesP-o-arom); 11B NMR (95 MHz, C6D6, RT): d=68.7 ppm (Dv1/2
=
=
1
valve. The reaction was monitored by H and 31P NMR spectrosco-
1100 Hz); 31P NMR (121 MHz, C6D6, RT): d=2.0 ppm (d, JPH
3
py. After heating at 508C for 4 days, the reaction mixture was fil-
tered with benzene. The solvent of the filtrate was removed under
reduced pressure. The residue was washed with benzene to afford
1,3-dihydro-1,3-dimesityl-2-selena-1-phospha-3-boraphenalene
(9Se, 31.3 mg, 64.5 mmol, 81%) as yellow crystals. 9Se: yellow crys-
19.8 Hz, 1JPSe =539 Hz); 77Se NMR (57 MHz, C6D6, 608C): d=
1
226.2 ppm (br d, JPSe =508 Hz); HRMS (FAB) m/z: found: 566.0635
[M]+; elemental analysis calcd (%) for C28H2811BP80Se2 (566.0362): C
59.60, H 5.00; found: C 59.61, H 5.10.
1
tals. M.p. 2128C (decomp.). H NMR (600 MHz, C6D6, RT): d=2.05 (s,
Treatment of 9S with elemental selenium: A C6D6 solution
(0.8 mL) of 9S (43.8 mg, 0.100 mmol) and elemental selenium
(11.8 mg, 0.150 mmol) was charged into an NMR tube with J-
3H, MesP-p-Me), 2.15 (s, 3H, MesB-o-Me), 2.22 (s, 3H, MesB-p-Me),
2.46 (s, 3H, MesB-o-Me), 2.58 (br s, 6H, MesP-o-Me), 6.73–6.74 (m,
2H, MesP-m-arom CH), 6.77–6.78 (m, 1H, MesB-m-arom CH), 6.85–
1
Young valve. The reaction was monitored by H and 31P NMR spec-
3
4
6.86 (m, 1H, MesB-m-arom CH), 6.90 (ddd, JHH =7.9, 7.3 Hz, JHP
=
troscopy. After heating at 1008C for 24 h, the reaction mixture was
filtered with benzene, and then the solvent of the filtrate was re-
moved under reduced pressure. The residue was reprecipitated
from its toluene/hexane solution to afford 1,3-dihydro-1,3-dimesi-
tyl-2-thia-1-phospha-3-boraphenalene-1-selenide 10SSe (42.5 mg,
82.0 mmol, 82%). 10SSe: yellow crystals. M.p. 2248C (decomp.).
1H NMR (600 MHz, C6D6, RT) d=1.85 (s, 3H, MesP-p-Me), 1.91 (s, 3H,
MesB-o-Me), 1.96 (s, 3H, MesB-o-Me), 2.16 (s, 3H, MesB-p-Me), 2.29
(s, 6H, MesP-o-Me), 6.38 (d, 4JHP =4.6 Hz, 2H, MesP-m-arom CH),
6.66–6.67 (m, 1H, MesB-m-arom CH), 6.76–6.77 (m, 1H, MesB-m-
2.2 Hz, 1H, Phen-8), 6.95 (dd, 3JHH =8.3, 7.0 Hz, 1H, Phen-5), 7.36
(dm, 3JHH =7.9 Hz, 1H, Phen-7), 7.52 (ddd, 3JHP =9.5 Hz, JHH
=
=
3
7.3 Hz, 4JHH =1.4 Hz, 1H, Phen-9), 7.59 (dd, 3JHH =8.3 Hz, JHH
4
1.4 Hz, 1H, Phen-6), 7.95 ppm (ddd, 3JHH =7.0 Hz, 4JHH =1.4 Hz,
5JHP =1.4 Hz, 1H, Phen-4); 13C NMR (150 MHz, C6D6, 258C): d=21.01
(MesP-p-CH3), 21.25 (MesB-o-CH3), 22.29 (MesB-p-CH3), 22.63 (MesB-o-
CH3), 23.55 (br, MesP-o-CH3), 23.68 (MesP-o-CH3), 125.42 (d, JCP
=
3
4.4 Hz, Phen-8-CH), 126.07 (d, 5JCP =1.2 Hz, Phen-5-CH), 127.94
(MesB-m-arom-CH), 128.28 (MesB-m-arom-CH), 129.3 (br, MesP-m-
arom-CH), 129.50 (d, 4JCP =3.6 Hz, Phen-7-CH), 130.0 (br, MesP-m-
arom CH), 6.91 (dd, JHH =8.1, 7.0 Hz, 1H, Phen-5), 7.14 (ddd, JHH
=
=
=
=
3
3
arom-CH), 130.48 (d, 2JCP =30.5 Hz, Phen-9-CH), 132.13 (d, JCP
=
8.1, 7.3 Hz, JHP =2.5 Hz, 1H, Phen-8), 7.46 (ddd, JHH =8.1 Hz, JHH
1
4
3
4
44.0 Hz, MesP-ipso-arom), 134.20 (br, Phen-3a), 135.32 (Phen-6a),
1.4 Hz, 4JHP =1.4 Hz, 1H, Phen-7), 7.52 (ddd, 3JHH =8.1 Hz, JHH
4
1
2
4
135.68 (d, JCP =45.9 Hz, Phen-9a), 135.87 (d, JCP =9.9 Hz, Phen-9b),
136.57 (d, 4JCP =2.0 Hz, Phen-6-CH), 136.97 (MesB-o-arom), 137.63
1.5 Hz, 4JHP =1.5 Hz, 1H, Phen-6), 7.82 (dd, 3JHH =7.0 Hz, JHH
1.5 Hz, 1H, Phen-4), 9.08 ppm (ddd, 3JHP =19.9 Hz, 3JHH =7.3 Hz,
4JHH =1.4 Hz, 1H, Phen-9); 13C NMR (150 MHz, C6D6, RT): d=20.49
(d, 5JCP =1.4 Hz, MesP-p-CH3), 21.21 (MesB-p-CH3), 22.08 (MesB-o-
CH3), 22.18 (MesB-o-CH3), 24.18 (br d, 3JCP =5.1 Hz, MesP-o-CH3),
126.17 (d, 3JCP =16.1 Hz, Phen-8-CH), 126.20 (Phen-5-CH), 127.79
(MesB-m-arom-CH), 128.13 (MesB-m-arom-CH), 130.89 (br, Phen-3a),
(MesB-p-arom), 138.48 (MesB-o-arom), 138.63 (d, JCP =2.3 Hz, Phen-
4
4-CH), 140.72 (d, JCP =1.2 Hz, MesP-p-arom), 141.78 (br, MesB-ipso-
4
arom), 145.56 (MesP-o-arom), 145.68 ppm (br, MesP-o-arom);
11B NMR (95 MHz, C6D6, RT) d=70.6 ppm (Dv1/2 =1050 Hz); 31P NMR
(121 MHz, C6D6, RT): d=ꢀ18.1 ppm (d, 1JPSe =179 Hz); 77Se NMR
Chem. Eur. J. 2014, 20, 3752 – 3758
www.chemeurj.org
3757
ꢁ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Full Paper
131.37 (d, 1JCP =72.0 Hz, MesP-ipso-arom), 131.58 (d, 1JCP =69.0 Hz,
Phen-9a), 131.93 (d, 3JCP =12.0 Hz, MesP-m-arom-CH), 133.30 (d,
3JCP =8.7 Hz, Phen-6a), 133.62 (d, 4JCP =3.5 Hz, Phen-7-CH), 134.31
(d, 2JCP =6.0 Hz, Phen-9b), 136.24 (Phen-6-CH), 137.96 (MesB-o-
2009, 3129–3136; g) P. Kilian, F. R. Knight, J. D. Woollins, Chem. Eur. J.
2011, 17, 2302–2328.
[2] a) M. Yamashita, K. Watanabe, Y. Yamamoto, K. Y. Akiba, Chem. Lett.
2001, 1104–1105; b) S. Bontemps, M. Devillard, S. Mallet-Ladeira, G.
Bouhadir, K. Miqueu, D. Bourissou, Inorg. Chem. 2013, 52, 4714–4720;
c) Y. F. Li, Y. Kang, S. B. Ko, Y. L. Rao, F. Sauriol, S. N. Wang, Organometal-
lics 2013, 32, 3063–3068; d) J. Beckmann, E. Hupf, E. Lork, S. Mebs,
Inorg. Chem. 2013, 52, 11881–11888.
[3] For reviews see: a) R. C. Fischer, P. P. Power, Chem. Rev. 2010, 110, 3877–
3923; b) R. T. Paine, H. Nçth, Chem. Rev. 1995, 95, 343–379.
[4] For examples see: a) S. J. Geier, T. M. Gilbert, D. W. Stephan, J. Am.
Chem. Soc. 2008, 130, 12632–12633; b) S. J. Geier, T. M. Gilbert, D. W.
Stephan, Inorg. Chem. 2011, 50, 336–344.
arom), 138.23 (br, MesB-ipso-arom), 138.33 (MesB-p-arom), 138.40 (d,
4
2JCP =15.0 Hz, Phen-9-CH), 138.73 (MesB-o-arom), 140.72 (d, JCP
=
3.0 Hz, MesP-p-arom), 141.53 (Phen-4-CH), 141.68 ppm (br, MesP-o-
arom); 11B NMR (95 MHz, C6D6, RT) d=65.9 ppm (Dv1/2 =1130 Hz);
3
1
31P NMR (121 MHz, C6D6, RT): d=19.7 ppm (d, JPH =19.9 Hz, JPSe
=
=
779 Hz); 77Se NMR (57 MHz, C6D6, RT): d=ꢀ16.6 ppm (brd, JSeP
1
779 Hz); HRMS (FAB) m/z: 519.0990 [M+H]+; elemental analysis
calcd (%) for C28H2911BPS80Se (519.0986): C 65.01, H 5.46; found: C
65.15, H, 5.45.
[5] A. Staubitz, A. P. M. Robertson, M. E. Sloan, I. Manners, Chem. Rev. 2010,
110, 4023–4078.
[6] a) X. D. Feng, M. M. Olmstead, P. P. Power, Inorg. Chem. 1986, 25, 4615–
4616; b) D. C. Pestana, P. P. Power, J. Am. Chem. Soc. 1991, 113, 8426–
8437.
X-ray crystallographic analysis of 9S, 9Se, 10SS, 10SeSe,
and 10SSe
[7] a) U. Vogel, P. Hoemensch, K. C. Schwan, A. Y. Timoshkin, M. Scheer,
Chem. Eur. J. 2003, 9, 515–519; b) U. Vogel, A. Y. Timoshkin, K. C.
Schwan, M. Bodensteiner, M. Scheer, J. Organomet. Chem. 2006, 691,
4556–4564; c) K. C. Schwan, A. Y. Timoskin, M. Zabel, M. Scheer, Chem.
Eur. J. 2006, 12, 4900–4908; d) A. Adolf, M. Zabel, M. Scheer, Eur. J.
Inorg. Chem. 2007, 2136–2143; e) A. Adolf, U. Vogel, M. Zabel, A. Y. Tim-
oshkin, M. Scheer, Eur. J. Inorg. Chem. 2008, 3482–3492.
[8] Synthesis of 1-phospha-2-boraacenaphthene 1 and its unique physical
properties have been already reported as a Communication, see: A.
Tsurusaki, T. Sasamori, A. Wakamiya, S. Yamaguchi, K. Nagura, S. Irle, N.
Tokitoh, Angew. Chem. 2011, 123, 11132–11135; Angew. Chem. Int. Ed.
2011, 50, 10940–10943.
Single crystals of 9S, 9Se, 10SS, 10SeSe, and 10SSe were grown
by slow recrystallization of their solution (THF/toluene at ꢀ408C
for 9S and 9SS, toluene/hexane at room temperature for 9Se and
10SeSe, toluene at room temperature for 10’SeSe and 10SSe) in
a glovebox filled with argon. The intensity data were collected on
a Rigaku Mercury CCD diffractometer with graphite-monochromat-
ed MoKa radiation (l=0.71070 ꢀ). The structure was solved by
direct method (SHELXS-97)[15] and refined by full-matrix least-
squares procedures on F2 for all reflections (SHELXL-97).[15] All hy-
drogen atoms were placed using AFIX instructions, whereas all the
other atoms were refined anisotropically. Crystallographic data for
the structure reported in this paper have been deposited with
Cambridge Crystallographic Data Centre as CCDC-973010 (9S),
CCDC-973011 (9Se), CCDC-973014 (10SS), CCDC-973013 (10SeSe),
CCDC-973012 (10’SeSe), and CCDC-973015 (10SSe). These data
can be obtained free of charge from The Cambridge Crystallo-
graphic Data Centre via www.ccdc.cam.ac.uk/data_request/cif.
[9] a) P. Kçlle, H. Nçth, R. T. Paine, Chem. Ber. 1989, 122, 423–426; b) H.
Nçth, S. Staude, M. Thomann, R. T. Paine, Chem. Ber. 1993, 126, 611–
618.
[10] a) D. Scheschkewitz, H. Amii, H. Gornitzka, W. W. Schoeller, D. Bourissou,
G. Bertrand, Science 2002, 295, 1880–1881; b) D. Scheschkewitz, H.
Amii, H. Gornitzka, W. W. Schoeller, D. Bourissou, G. Bertrand, Angew.
Chem. 2004, 116, 595–597; Angew. Chem. Int. Ed. 2004, 43, 585–587.
[11] There are a few examples of heterocycles bearing phosphorus, boron,
or chalcogen atoms at 1,8-position in a naphthalene skeleton. For ex-
amples, see: a) A. M. Z. Slawin, D. J. Williams, P. T. Wood, J. D. Woollins, J.
Chem. Soc. Chem. Commun. 1987, 1741–1741; b) M. R. S. Foreman, J.
Novosad, A. M. Z. Slawin, J. D. Woollins, J. Chem. Soc. Dalton Trans.
1997, 1347–1350; c) P. Kilian, S. Parveen, A. L. Fuller, A. M. Z. Slawin,
J. D. Woollins, Dalton Trans. 2008, 1908–1916; d) Y. Kim, H. Zhao, F. P.
Gabba¨ı, Angew. Chem. 2009, 121, 5057–5060; Angew. Chem. Int. Ed.
2009, 48, 4957–4960; e) H. Y. Zhao, F. P. Gabba¨ı, Nat. Chem. 2010, 2,
984–990; f) R. S. Grainger, A. Procopio, J. W. Steed, Org. Lett. 2001, 3,
3565–3568; g) R. S. Grainger, B. Patel, B. M. Kariuki, L. Male, N. Spencer,
J. Am. Chem. Soc. 2011, 133, 5843–5852.
Acknowledgements
This work was partially supported by Grants-in-Aid for Scientif-
ic Research (B) (No. 22350017), Young Scientist (A) (No.
23685010), Scientific Research on Innovative Areas, “New Poly-
meric Materials Based on Element-Blocks” [#2401] (No.
25102519), Scientific Research on Innovative Areas, “Stimuli-re-
sponsive Chemical Species for the Creation of Functional Mole-
cules” [#2408] (No. 24109013), and MEXT Project of Integrated
Research on Chemical Synthesis from Ministry of Education,
Culture, Sports, Science and Technology (MEXT), Japan.
[12] Selected structural parameters of theoretically optimized structure of
10SeSe and 10’SeSe at the B3PW91/6-311(3d) level. 10SeSe: P1ꢀSe1,
2.269, Se1ꢀB1, 1.939, P1ꢀSe2, 2.112 ꢀ, P1-Se1-B1, 99.318. 10’SeSe: Pꢀ
Se1, 2.194, Se1ꢀB, 2.213, PꢀSe2, 2.194, BꢀSe2, 2.213 ꢀ, P-Se1-B, 74.628,
P-Se2-B, 74.62, Se1-B-Se2, 93.35, Se1-P-Se2, 94.408.
[13] R. P. Davies, M. G. Martinelli, Inorg. Chem. 2002, 41, 348–352.
[14] A. B. Pangborn, M. A. Giardello, R. H. Grubbs, R. K. Rosen, F. J. Timmers,
Organometallics 1996, 15, 1518–1520.
[15] a) G. M. Sheldrick, Acta Crystallogr. Sect. A 1990, 46, 467–473; b) G. M.
Sheldrick, SHELX-97 Program for Crystal Structure Solution and the Re-
finement of Crystal Structures, Institꢂt fꢂr Anorganische Chemie der
Universitꢃt Gçttingen, Tammanstrasse 4, 3400 Gçttingen, Germany,
1997.
Keywords: boron · chalcogens · heterocycles · phosphorus ·
reduction · synthetic methods
[1] Recent reviews see: a) D. W. Stephan, Org. Biomol. Chem. 2012, 10,
5740–5746; b) D. W. Stephan, S. Greenberg, T. W. Graham, P. Chase, J. J.
Hastie, S. J. Geier, J. M. Farrell, C. C. Brown, Z. M. Heiden, G. C. Welch, M.
Ullrich, Inorg. Chem. 2011, 50, 12338–12348; c) G. Erker, Dalton Trans.
2011, 40, 7475–7483; d) D. W. Stephan, Chem. Commun. 2010, 46,
8526–8533; e) D. W. Stephan, G. Erker, Angew. Chem. 2010, 122, 50–81;
Angew. Chem. Int. Ed. 2010, 49, 46–76; f) D. W. Stephan, Dalton Trans.
Received: November 27, 2013
Published online on February 23, 2014
Chem. Eur. J. 2014, 20, 3752 – 3758
www.chemeurj.org
3758
ꢁ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim