Isolation and structures of some selenium and tellurium derivatives of 1, 4, 5, 8, 9, 12-hexabromododecahydrotriphenylene as co-crystals of triphenylene

Article abstract of DOI:10.1007/s12039-014-0713-x

The synthesis and characterization of low-valent organoselenium and tellurium derivatives of hexabromododecahydrotriphenylene has been attempted. The reaction of hexabromododecahydrotriphenylene with in situ generated disodium dichalcogenides (Na₂E₂; E = Se, Te) afforded insoluble chalcododecahydrotriphenylene derivatives, 20, 21 respectively. Attempted aromatization of 20 and 21 using DDQ (2, 3-dichloro-5, 6-dicyano-1,4-benzoquinone) as an oxidizing agent afforded the co-crystals. The hexaselenophenyl derivative, 22 and the hexaselenocyanate derivative 23 were synthesized by the reaction of in situ generated sodium arylselenolate/potassium selenocyanate with hexabromododecahydrotriphenylene, respectively. The compounds were characterized by common spectroscopic tools and a few by single crystal x-ray crystallographic studies.

Full text of DOI:10.1007/s12039-014-0713-x

c
J. Chem. Sci. Vol. 126, No. 5, September 2014, pp. 1311–1321. ꢀ Indian Academy of Sciences.
Isolation and structures of some selenium and tellurium derivatives
of 1, 4, 5, 8, 9, 12-hexabromododecahydrotriphenylene as co-crystals
of triphenylene
POONAM RAJESH PRASADa, HARKESH B SINGHa,∗ and RAY J BUTCHERb
aDepartment of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400 076, India
bDepartment of Chemistry, Howard University, Washington DC, 20059, USA
e-mail: chhbsia@chem.iitb.ac.in
MS received 28 May 2014; revised 8 July 2014; accepted 11 September 2014
Abstract. The synthesis and characterization of low-valent organoselenium and tellurium derivatives of
hexabromododecahydrotriphenylene has been attempted. The reaction of hexabromododecahydrotripheny-
lene with in situ generated disodium dichalcogenides (Na2E2; E = Se, Te) afforded insoluble chalcodo-
decahydrotriphenylene derivatives, 20, 21 respectively. Attempted aromatization of 20 and 21 using DDQ
(2, 3-dichloro-5, 6-dicyano-1,4-benzoquinone) as an oxidizing agent afforded the co-crystals. The hexase-
lenophenyl derivative, 22 and the hexaselenocyanate derivative 23 were synthesized by the reaction of in situ
generated sodium arylselenolate/potassium selenocyanate with hexabromododecahydrotriphenylene, respec-
tively. The compounds were characterized by common spectroscopic tools and a few by single crystal x-ray
crystallographic studies.
Keywords. Hexabromododecahydrotriphenylene; organoselenide; –telluride; selenocyanate.
1. Introduction
atoms into the frameworks of extended π-conjugated
system of PAHs is to improve their inter-chain cou-
pling and to suppress the Peierls transition.7–9 Among
chalcogens, selenium and tellurium are more interest-
ing due to their larger sizes and higher polarizabil-
ity compared to sulfur. In the present study we report
our attempts to insert heteroatoms like selenium and
tellurium at the peripheral positions of the tripheny-
lene rings using nucleophilic substitution reaction with-
out any substitution on the triphenylene rings. During
the course of the present study, Shao and co-workers10
have reported the insertion of sulfur and selenium het-
eroatoms at the peripheral positions of the triphenylene
rings (16–17). In this case they succeeded in incorpo-
rating sulfur and selenium by electrophilic substitution
reaction using n-BuLi as reagent followed by chalcogen
(S, Se) insertion.
The design and synthesis of polycyclic aromatic hydro-
carbons (PAHs) have attracted considerable interest
due to their potential application in various fields
such as organic photovoltaic cells, semiconductors,
liquid-crystalline materials and polymer research.1–3
Among PAHs, fullerene is one of the most studied
molecules because of its symmetric structure and inter-
esting semiconductor properties. The smallest subunit
of fullerene is the bowl-shaped corannulene (1) and
a concentric zwitterion ‘annulene-within-an-annulene’
resonance structure (1a) might contribute to the elec-
tronic properties of 1 (chart 1).2
Similar to corannulene (1), the other simple symmet-
ric structures of PAHs are correnes (2) and sumanene
(4), which are not only attractive as siblings of
fullerenes but attractive for their own physical and
chemical properties.4 Triphenylene (3) is of special
interest as a substrate for use as precursor for the
synthesis of graphenes, buckminsterfullerenes, carbon
nanotubes, as well as polycyclic heteroaromatics. It is
known that the insertion of heteroatoms such as sulfur
(5–8) into 3 enhances their electronic properties. Some
other sulfur substituted PAHs synthesized for such stud-
ies are 9–15.3–6 The main aim of introducing chalcogen
2. Experimental
2.1 Materials
Drycyclohexanone (Spectrochem, India), ZrCl4(Sigma-
Aldrich), bromine solution (Merck, India), potassium
selenocyanate (Sigma-Aldrich), sodium borohydride
(Merck, India), 2, 3-dichloro-5, 6-dicyanobenzoquinone
(DDQ) (Sigma-Aldrich), selenium/tellurium powder
∗For correspondence
1311

1312
Poonam Rajesh Prasad et al.
a stationary phase whereas petroleum ether and ethyl
acetate (2%) were used as the mobile phase.
2.3 Synthesis of hexaselenododecahydrotriphenylene
(20)
A stirred solution of disodium diselenide {generated in-
situ by the reaction of sodium (0.19 g, 8.42 mmol) and
selenium (0.66 g, 8.42 mmol) in dry THF in the pres-
ence of catalytic amount of naphthalene} was treated
with precursor 19 (1.00 g, 1.4 mmol) dissolved in DMF
(5 mL) and DMSO (10 mL). The reaction mixture was
stirred at room temperature for 12 h. The resulting mix-
ture was poured into water to get a yellow precipitate.
This was collected by vacuum filtration, washed with
water and ethanol and dried under vacuum to get a yel-
low solid. The crude product was insoluble (vide infra)
in all common solvents including DMSO and was used
as such for further reactions. Yield: 0.5 g (28%), M.p.:
> 250◦C Anal. Calc. for C18H18Se6: C, 30.53; H, 2.56.
Found: C, 28.06; H, 2.09%.
Chart 1. A few polycyclic aromatic hydrocarbons (PAHs)
and heteroaromatics.
2.4 Synthesis of tetratellurododecahydrotriphenylene
(21)
(Sigma-Aldrich) were used as received. Dodecahy-
drotriphenylene (18)11 and 1,4,5,8,9,12-hexabromo-
dodecahydrotriphenylene (19)11 were prepared by
following the literature procedures. The solvents were
purified and dried by standard procedures and were
freshly distilled prior to use.
It was synthesized from the reaction of disodium ditel-
luride (generated in-situ) with 19 (1.00 g, 1.4 mmol) in
DMF (5 mL) and DMSO (10 mL), following the pro-
cedure used for the preparation of compound 20. The
crude product was insoluble (vide infra) in all common
solvents including DMSO and was used as such for fur-
ther reactions. Yield: 0.4 g (38%) M.p.: > 250◦C. Anal.
Calc. for C18H18Te4: C, 29.03; H, 2.44. Found: C, 28.03;
H, 1.90%.
2.2 Physical measurements
Melting points were recorded in capillary tubes. For
most of the compounds, NMR spectra were recorded in
CDCl3 solvent and for some using CD3 OD or DMSO-
2.5 Synthesis of hexaselenophenyldodecahydrotri-
phenylene (22)
1
d6. The H (400 MHz), 13C (100 MHz), 77Se (76.4
MHz) and 125Te (126.3 MHz) spectra were recorded
on a Bruker 400 MHz spectrometer. Chemical shifts To an ethanolic solution of diphenyl diselenide (0.51 g,
cited were referenced with respect to TMS for (1H and 1.63 mmol) was added an excess of sodium borohydride
13C) as internal standard and Me2Se (for 77Se), Me2Te (0.12 g, 3.26 mmol) at 0◦C. To this, a solution of 19
(for 125Te) as external standards. Elemental analysis (0.39 g, 0.54 mmol) in DMF (5 mL) was added and the
was performed on Carlo-Erba model 1106 and Eager reaction mixture allowed to stir for additional 6 h (mon-
300 EA112 elemental analyzers. The IR spectra were itored by TLC) at room temperature. The reaction mix-
recorded in the range of 400–4000 cm−1 by using KBr ture was then poured into water and the organic layer
pellets for solid samples and as neat film for liquid sam- was extracted with diethyl ether and dried over sodium
ples on a Thermo Nicolet Avatar 320 FT-IR spectrom- sulfate. The organic layer was evaporated to afford 22
eter. ESI-MS were recorded at room temperature on a as yellow oil. The oil was triturated with petroleum
Q-TOF micro (YA-105) mass spectrometer with elec- ether and diethyl ether (2:1) to give a white solid. Yield:
1
trospray ionization mode of analysis. In the case of iso- 0.20 g (33%). M.p. 237−239◦C. H NMR (400 MHz,
topic patterns, the value given is for the most intense CDCl3): δ (ppm): 7.59–7.24 (m, 30H), 5.59 (s, 6H),
peak. In column chromatography, silica gel was used as 2.87–2.80 (d, 6H), 1.99–1.97(d, 6H); 13C NMR (75

Isolation and structures of some selenium and tellurium derivatives
1313
MHz, CDCl3): δ 25.2, 42.0, 127.8, 129.4, 131.0, 134.3, analysis values of the mixtures of compounds 3 and
134.7; 77Se NMR (CDCl3): δ 462. ES-Ms m/z calcd. 24, 25 before crystallization (from powder) are given
for C54H48Se6: 1170; found: 1016 [M-SePh]+; 636 below:
[M-Se3Ph4+Na]. Anal.Calc. for C54H48Se6: C, 55.40;
(i) Anal.Calcd. for C54H30Se3: C, 70.83; H, 3.30.
H, 4.13. Found C, 54.68; H, 4.12%.
Found: C, 70.50; H, 4.07%.
(ii) Anal.Calcd. for C54H30Se3: C, 70.83; H, 3.30.
Found: C, 73.61; H, 3.76%.
(iii) Anal.Calcd. for C54H30Se3: C, 70.83; H, 3.30.
Found: C, 73.57; H, 3.07%.
2.6 Synthesis of hexaselenocyanatedodecahydrotri-
phenylene (23)
To a stirred solution of 19 (0.50 g, 0.70 mmol) in dry
tetrahydrofuran (30 mL) was added KSeCN (0.61 g,
4.20 mmol) and the solution stirred for 10 h at room
temperature. The resultant reaction mixture was then
poured into water. The precipitate was filtered, washed
with water and finally washed with methanol to get
a pale yellow solid of 23. Yield: 0.21 g (34%). M.p.
After column chromatography and repeated crystalliza-
tions, the elemental analysis data obtained on crys-
tals are given below. The elemental analysis data and
other data (vide infra) showed it to be co-crystal of
compounds 3 and 24.
(i) Anal.Calcd. for C18H11.64Se0.36: C, 84.33; H, 4.57.
Found: C, 84.51; H, 4.36%.
(ii) Anal.Calcd. for C18H11.59Se0.41: C, 83.07; H, 4.49.
Found: C, 83.88; H, 4.82%.
1
224−226◦C. H NMR (400 MHz, CDCl3), δ (ppm):
5.8 (s, 6H), 2.84 (d, J = 12 Hz, 6H), 2.50 (d, J =
12 Hz, 6H); 13C NMR (75 MHz, CDCl3), δ (ppm):
25.23, 26.22, 44.31, 67.13, 104.39, 134.42; 77Se NMR
(CDCl3): δ 411. ES-MS m/z calcd. for C24H18Se6N6:
864; found: 883 [M + K]+; IR (KBr, cm−1): 2148.4
(νC≡N); Anal.Calc. for C24H18Se6N6: C, 33.36; H, 2.10;
N, 9.72. Found C, 34.13; H, 1.95; N, 7.562%.
2.8 Synthesis of tellurotriphenylene (26)
Similarly, the crude solid of 21 (1.0 g) was suspended
in dry chlorobenzene (20 mL) containing DDQ and
refluxed for 12 h and following a procedure similar to
that used for the synthesis of 24–25. The yellow solid
obtained was purified by column chromatography and it
always eluted as a mixture of two components 3 and 26.
Yield: 0.14 g. M.p. > 250◦C (decomp.). 1H NMR (400
MHz, CDCl3) mixture of 3 and 26, δ (ppm): 8.65–8.64
(m, 2H), 8.57 (d, 2H), 8.02 (d, 2H), 7.60 (d, 2H); 125Te
NMR (CDCl3): δ 625; ES-MS: m/z (%) 479 [M]+. (i)
Anal.Calcd. for C72H46Te: (C18H12 : C18H8Te, 3:1) C,
83.25; H, 4.46; Found: C, 84.28; H, 4.68%.
2.7 Synthesis of selenotriphenylene (24–25)
The crude solid of 20 (1.0 g) was suspended in dry
chlorobenzene (20 mL) containing DDQ and refluxed
for 12 h. After this, it was allowed to cool to the room
temperature. The reaction mixture was washed with
aqueous Na2SO3 solution until the solution became
colourless. The organic layer was dried over Na2SO4
and concentrated under reduced pressure to afford a
residue, which was purified by chromatography on sil-
ica gel using petroleum ether and ethyl acetate (2%) to
get a mixture of products. The isolation of these com-
pounds was very difficult due to their similar polarity
and sensitivity to decomposition to form 3. Hence the
compounds were characterized as mixture (vide infra).
Yield: 0.22 g. M.p. > 250◦C (decomp.);1H NMR (400
The experiment was repeated twice and different
results were obtained.
Anal. cacld for C72H46Te (C18H12 : C18H8Te, 8:1): C,
89.25; H, 4.90; Found C, 89.48; H, 5.06%.
2.9 X-ray data collection and structure refinement
MHz, CDCl3) mixture of 3,24 and 25, δ (ppm): 8.65– The single crystal x-ray diffraction measurements com-
8.64 (m, 2H), 8.63–8.51 (m, 2H), 8.40 (d, 2H), 8.07 (d, pounds 3, 3–24 a, b, c (as co-crystal) and 3-26 (as co-
2H), 7.76 (d, 2H), 7.6 (m, 2H); 13C NMR (75 MHz, crystals) were performed by using an Oxford Diffrac-
CDCl3), δ(ppm): 118.0, 118.16, 123.4, 123.6, 124.0, tion Gemini Diffraction measurements device with
124.1, 124.3, 127.2, 127.3, 127.4, 127.5, 127.6, 127.7, graphite monochromated MoK/α radiation (λ = 0.7107
130.0, 130.1, 130.3, 130.5, 130.5, 130.6, 133.4; 133.6, Å). The structures were determined by routine heavy-
138.8, 139.0; 77Se NMR (CDCl3): δ(ppm): 498, 459; atom method using SHELXS 9712 (Fourier methods)
ES-MS m/z calcd. for C36H18Se3: 689; found: 690 and refined by full-matrix least-squares with the non-
[M+1]; 611[C18H8Se2 + C18H12 + H]+.
and similar results were obtained. The three elemental of SHELXS 97 program.13 Scattering factors were from
hydrogen atom anisotropic and hydrogen atoms with
The experiment was repeated two more times fixed isotropic thermal parameters of 0.07 Å by means

1314
Poonam Rajesh Prasad et al.
reaction of PhSeNa with 19 at 0◦C. The elemental
analysis suggested the formation of compound 22.
The synthesis of the selenocyanate derivative, 23 was
accomplished by the addition of KSeCN to a tetrahyro-
furan solution of 19 at room temperature (scheme 1).
common sources.14 The crystallographic data for 3, co-
crystals of 3–24(a, b, c) and co-crystal of 3-26 are given
in table 1.
1
The H NMR spectrum of 22 exhibits signals in
3. Results and Discussion
the range of 7.41–7.25 ppm corresponding to the aro-
matic protons, a signal at 5.53 ppm for CH protons adja-
cent to the selenium atoms and other signals in the
range of 2.57–1.98 ppm for (CH2) protons. The CH pro-
tons adjacent to the selenium atoms are shifted upfield
(5.53 ppm) when compared to the CH protons adjacent
to bromine atoms in precursor 19 (6.13 ppm). Sim-
ilarly, in the case of selenocyanate 23, the CH pro-
tons appeared in the upfield region (5.78 ppm) as com-
pared to the precursor 19 and the alicyclic protons
were observed in the region of 3.59–2.47 ppm. The 77Se
NMR signal for 22 was observed at 462 ppm which is
slightly more (∼50 ppm) downfield shifted as compared
to that expected for monoselenides.16 This value of
462 ppm is also downfield shifted as compared to bis(2-
formylphenyl)selenide (393 ppm).17 For selenocyanate
23, the 77Se NMR chemical shift was 411 ppm, which is
close to the chemical shifts reported for the related RSe-
C≡N derivatives.18 The 13C NMR spectrum of 22 shows
seven peaks expected for the seven carbons, which are
3.1 Synthesis
The precursor, 1, 4, 5,8, 9, 12-hexabromododecahy-
drotriphenylene 19, was prepared by the reaction of
dodecahydrotriphenylene 18 with bromine following
the literature procedure.11,15 Organochalcogen deriva-
tives 20 and 21 were synthesized by the reaction of 19
with in situ generated Na2E2(E = Se and Te) at room
temperature (scheme 1). Compounds 20 and 21 were
obtained as yellow and as black solids, respectively. The
crude products could not be purified further and char-
acterized properly owing to their poor solubility in the
common organic solvents and were used as obtained for
further reactions. Wei et al. have also obtained a similar
insoluble product during the reaction of 19 with sodium
sulfide.11 The elemental analysis indicated the forma-
tion of the desired products 20 and 21. The FT-IR spec-
tra of 20 and 21 showed a different pattern as compared
to precursor 19. Compound 22 was synthesized by the
Table 1. Crystal data and structure refinement for co-crystals of 3, 3-24 (a,b,c) and 3-26.
Parameter
3
3-24a
3-24b
3-24c
3-26
Formula
Formula Weight
Temperature
Wavelength (Å)
Crystal System
Space Group
a (Å)
C18 H18
228.28
123(2) K
1.54184
Orthorhombic Orthorhombic
P212121
5.26628(17)
12.9714(4)
16.6563(5)
90
C18 H11.64 Se0.36 C18 H11.70 Se0.30 C18 H11.59 Se0.41 C18 H11.98 Te0.02
256.17
296(2) K
1.54178
251.55
259.44
230.79
123(2) K
1.54184
Orthorhombic
P212121
5.27903(15)
13.2092(9)
16.7456(6)
90
123(2) K
1.54184
Orthorhombic
P212121
5.2728(3)
13.3470(11)
16.7410(11)
90
123(2) K
0.71073
Orthorhombic
P212121
5.25999(1)
12.9652(4)
16.6417(4)
90
P212121
5.2507(5)
13.804(2)
16.782(2)
90
b (Å)
c (◦Å)
α(◦)
γ ( )
β(◦)
90
90
90
90
90
90
90
90
90
90
Volume (Å3)
Z
D (Mg/m3)
1137.81(6)
4
1.333
1216.4(3)
4
1.399
1167.70(9)
4
1.431
1178.17(14)
4
1.463
1134.91(5)
4
1.351
Abs. Coef. (mm-1) 0.572
Crystal Size (mm) 0.4 × 0.28
× 0.17
1.786
1.645
1.996
0.126
0.49 × 0.15
× 0.06
8010
0.45 × 0.12
0.48 × 0.15
0.50 × 0.23
× 0.08
× 0.10
× 0.13
Total Reflections
7640
2717
2687
31286
Unique Ref. (Rint) 2324 (0.0375) 2489 (0.0349)
1832 (0.0287)
Multi-scan
0.622, 1.000
0.062, 0.167
0.37, −0.41
1899 (0.0208)
Analytical
0.560, 0.828
0.0389, 0.112
0.28, −0.13
7319 (0.0472)
Analytical
0.898, 0.962
0.0639, 0.1501
0.48, −0.34
Abs. Correction
Tmin & Tmax
R1, wR2
Multi-scan
0.956, 1.000
0.055, 0.151
0.95, −0.195 0.73, −0.21
Multi-scan
0.702, 1.000
0.080, 0.248
Diff. peak & hole
(e.Å3)

Isolation and structures of some selenium and tellurium derivatives
1315
18
CN
Se
NC Se
Se
(i)
Se
Se
CN
CN
Se
Se
Se
Se
(v)
Br
Br
(ii)
NC Se
Se
CN
Se
Br
Br
20
23
Br
Br
19
(iii)
Te
Te
Te
(ivi)
Te
21
Se
Se
Se
Se
Se
Se
22
Scheme 1. Reagents and conditions: (i) Br2, dry CC14; (ii) Na2Se2, THF, 24
h, r.t.; (iii) Na2Te2, THF, 24 h, r.t.; (iv) PhSeNa, dry EtOH; (v) KSeCN, dry
THF, 10 h, r.t.
significantly upfield shifted compared to the precursor telluride 26 were obtained as mixture containing 3
19. In the FT-IR spectrum of compound 23, the absorp- in very low yields respectively (scheme 2). However,
tion at 2148 cm−1 is assigned to υC ≡ N stretching. In when the reaction mixture was refluxed for a short
the mass spectrum of 23, the molecular ion peak was period of time, most of the starting material was found
observed at m/z 887 [M + Na]+. However, in the case to have remained unreacted. The purification of the
of selenocyanate 22, the molecular ion peak was not aromatized organochalcogenides (24–25 and 26) was
observed and the base peak observed at m/z 1016 cor- extremely difficult by usual methods (recrystalliza-
responded to [M-SePh]+ where (M = C54H48Se6) and tion and column chromatography) due to their similar
m/z 636 corresponding to the [C30H28Se3 + Na]+.
polarity and sensitive nature of the compounds which
Aromatization of 20–21 to obtain organoselenide 24– decompose to triphenylene (3). It is worth mention-
25/and -telluride 26 was attempted using DDQ as the ing that Klemm et al. have also reported to get a mix-
oxidizing agent. The resulting derivatives 24–25 and ture of 3, 6 and 7 during the preparation of 7 in low
E
E
E
(i)
+
E
+
E
E
(E)n
20 E = Se, n = 2
26
E= Se
27 E=Te
3
24 E = Se
25 E=Te
21
E = Te, n = 1
Scheme 2. Reagents and conditions: (i) DDQ, PhCl, reflux, 10 h.

1316
Poonam Rajesh Prasad et al.
yields by the direct reaction of triphenylene (3) with 3.2 X-ray crystallographic study
hydrogen sulfide in the presence of heterogeneous cat-
alyst at high temperature temperature (500−550◦C).19
Similarly, Imamura’s group prepared trithiosumane (5)
in 2% yield by flash vacuum pyrolysis (FVP)20 and
very recently Wei and co-workers synthesized the poly-
cyclic pentathioaromatic (9) by a modified procedure
in 20% yield.11 Here, it might be difficult to intro-
duce selenium or tellurium at the peripheral positions
of triphenylene 3 rings simultaneously owing to their
larger size. The existence of the mixture of compounds
was inferred from the elemental analysis. The elemental
analysis showed different values for each preparation.
In the elemental analysis data, the carbon percentage
was very high (C = 80–89%) and indicated the pres-
ence of the hydrocarbon (triphenylene 3) as the major
impurity. Several attempts were made to isolate pure 24
and 25 (selenide) or 26 (telluride), however, every time
elemental analysis showed different values. This obser-
vation was further corroborated by single crystal x-
ray structure analysis (vide infra). After crystallization,
the elemental analysis ratio was different than the ratio
found for the powdered (crude) samples. In the mass
spectrum of the mixture of selenides, the molecular ion
peaks were observed at m/z 315 [M+Na]+ for 24 and at
m/z 392 [M+Na]+ for25. It also showed the combined
peak for 24+25 at 690 [M + 1]+. However, the single
crystal x-ray structure analysis indicated the presence
of only one selenium compound 24 (vide infra) along
with 3. Though in the case of the tellurium derivative,
the molecular ion peak observed at m/z 447 for [M]+
which indicated that two tellurium atoms were present
at the peripheral positions of the triphenylene rings, i.e.
formation of 27, the single crystal X-ray structure anal-
ysis again indicated the presence of only one tellurium
compound (26) in small ratio (vide infra) along with 3.
The crystal data for the 5 compounds are listed in
table 1. The structures of 4 co-crystals of triphenylene
with various amounts mono-selenium and tellurium
substituted triphenylene are reported as well as a low
temperature structure of triphenylene itself.
The structure of triphenylene has previously been
reported22 but this structure was based on film data at
room temperature whereas the present study reports the
structure based on diffractometer data at 123 K. Co-
crystals of triphenylene with other arene type molecules
have previously been reported23 and result in interesting
architectures.24 Since this is a more accurate structure
of the important arene, triphenylene (figure 1), some
comparison with the earlier results should be made. In
the original paper of Ahmed & Trotter23 it was noted
that the aromatic molecule as a whole was significantly
non-planar while the central ring was basically planar.
In addition, the non-planarity shown by the outer six-
membered rings showed a pattern where the two rings
were displaced in one direction from this central plane
while the other ring was displaced in the opposite direc-
tion. In the original paper the unique ring was labelled
as A while the other two rings were labelled as B and
C. In the present structure the A ring is C3 C4 C11
C12 C13 & C14 while B corresponds to C1 C2 C7
C8 C9 & C10 and C to C5 C6 C15 C16 C17 & C18
(figure 1). For the central ring composed of C1 through
C6, the rms deviation of the 6 fitted atoms is 0.0065(16)
Å while each individual outer ring is also planar (rms
1
The H NMR spectrum of the mixture of 3, 24 and
25 (powder) showed the expected three sets of peaks
in the region of 8.65–7.57 ppm corresponding to the
3 (8.55 and 7.56 ppm), 24 (8.39 and 8.05 ppm) and
25 (8.65 and 7.78 ppm). It was further corroborated
by 13C NMR spectrum. The 13C NMR spectrum (after
long time data accumulation) also showed expected
twenty one peaks related to all three compounds (3, 24
and 25). It was further confirmed by 77Se NMR spec-
trum. In the 77Se NMR, two peaks were observed at
498 and 459 ppm. Similar to the selenides 24 and 25,
compounds 3, and 26 also showed a complex pattern
1
in the H NMR spectrum, however, the 125Te NMR
spectrum showed a single at 625 ppm. This is slightly
upfield shifted (∼37 ppm) compared to the reported
monotelluride, bis[2-(phenylazo)phenyl-C, N]telluride
(667 (667 ppm).21
Figure 1. Molecular structure of 3.

Isolation and structures of some selenium and tellurium derivatives
1317
be discussed in turn starting with 3–24a (figure 2). A
direct comparison of cell constants is made difficult
for this structure due to the differences in temperature
between the two structures. Obviously it is generally
expected that at the higher temperature the cell volume
should be larger than at low temperature and this is
observed. A more meaningful comparison will be made
for the LT Se structures. As far as the Se substitution
for this structure is concerned, all the spectroscopic evi-
dence points to a mono substitution of the tripheny-
lene skeleton. However, in the X-ray structure the mono
Se substitution shows up in two positions at a ratio
of 3.79:1.00 and this substitution has a dramatic effect
on the conformation adopted by the triphenylene skele-
ton. As in the un-substituted derivative, both the central
ring and the three outer rings are planar (rms deviations
from planarity of 0.0074(23), 0.0098(23) 0.0119(30)
and 0.0053(30) Å, respectively for the central ring and
three outer rings). However, while in the un-substituted
derivative there are clearly rings A, B and C based on
distortions from planarity, in the present case all the
carbon atoms form one outer ring (C13 C14 C15 C16
and C17) deviate from the central in the same direc-
tion but this is not true for the other two outer rings.
In the case of the ring composed of C1 C2 C3 C4
C5 and C6, the atoms C2 and C3 deviate substantially
in the opposite direction while in the other ring (C7
C8 C9 C10 C11 and C12) the outermost two atoms,
C10 and C11 have only small deviations but in oppo-
site directions (0.0061(66) and -0.0239(77) Å, respec-
tively). There are similar changes in the bond lengths.
While in the central ring there is a similar pattern of
alternating shorter and longer C-C bond lengths, in the
outer rings the pattern is not so clearly established. This
is especially the case with the ring composed of C1
through C6 where all the C-C bonds are all of similar
length. One noticeable effect of the substitution is the
fact that the dihedral angles between the planes of the
outer rings and the central ring (0.78(25)◦ for C1 to C6,
and 1.40(27)◦ and 1.40(58)◦ for the other two rings)
are much smaller than in the un-substituted derivative.
As far as the packing is concerned it appears that the
substitution has not had a major effect on the π −
π stacking compared to the un-substituted derivative
(table 2).
deviations of 0.0045(15), 0.0074(15) and 0.0033(15) Å
for A, B, and C, respectively). The dihedral angles
between the outer rings and central ring are 1.30(15)◦,
2.42(16)◦ and 2.19(15)◦, for A, B and C, respectively.
The central ring shows a pronounced pattern of alternat-
ing short and longer bonds with the shorter C-C bonds
being those which are part of the outer rings. The C-
C bond lengths for each outer ring also show a pattern
with the C-C bonds involving the carbon atoms of the
central ring being significantly longer (1.409(3)◦) than
those involving only outer rings (1.381(3)◦). As was
noticed in the original report, the closest π-π stack-
ing involve ring A with rings B and C in neighbouring
molecules (in this case, ring A corresponds to C3 C4
C11 C12 C13 and C14; ring B to C1 C2 C7 C8 C9 and
C10; ring C to C5 C6 C15 C16 C17 C18).
For the substituted triphenylenes there are three
mono-Se substituted derivatives (3–24a, 3–24b, 3–24c)
(as well as one mono-Te) substituted triphenylene
(3–26). For the Se derivatives, the structure of
3–24a was carried out at room temperature (RT) with
0.36 Se substitution while there were two (3–24b and
3–24c) low temperature (LT) structures (123 K) with
0.30 and 0.41 Se substitution. In addition, there was
one (3–26) LT structure with Te substitution (0.02). The
effect of the substitution for each can be found by com-
parison of the cell constants, metrical parameters and
π-π stacking interactions of each with the un-
substituted triphenylene structure. Each structure will
The X-ray analysis of the second Se derivative
(3-24b) (this is dealt with first as it has the lower
Se substitution) was carried out at LT (123 K). The
extent of the substitution was 0.30 Se per tripheny-
lene molecule. As in the RT derivative previously dis-
cussed the substitution pattern shows two positions for
the Se in an atom ratio of 1.92:1. Since this struc-
ture was carried out at the same temperature as for the
Figure 2. Molecular structure of 24: Selected bond (Å)
lengths and bond angles (◦): Se(1)-C(7A) 1.751(6), Se1-
C(1A) 1.904(5), C(7)-Se(1)-C(1A) 100.8(2), C(6)-C(1A)-
Se(1) 98.5(3), C(2)-C(1A)-Se(1) 141.5(4).

1318
Poonam Rajesh Prasad et al.
Table 2. Intermolecular and interplanar distances.
1· · · 1
slippage
A· · · A
slippage
B· · · B
slippage
4.062
C· · · C
slippage
4.058
Cg· · · Cg
3
3.4
4.022
3.945
4.02
4.005
4.022
3.31
3.469
4.096
3.942
3.352
3.356
3.714
3.846
3-24a*
3-24b
3-24c
3-26
3.465
3.388
3.429
3.4
3.388
3.362
3.31
4.049
4.062
4.096
3.37
3.394
3.352
4.063
4.035
4.022
3.356
4.058
3.714
* B & C
not determined
un-substituted molecule a comparison of the effect on
crystal data can be made. The largest change in cell con-
stants is for the b axis where the length has changed
from 12.9714(4) to 13.2092(9) Å. There are similar but
less dramatic lengthening of both a and c. Consequently
there is a significant increase in overall cell volume
from 1137.81(6) Å3 to 1167.70(9) Å3 and an increase
in overall crystal density from 1.333 to 1.431. Both
the central ring and three outer rings are planar (rms
deviations of 0.0040(26), 0.0065(29), 0.0071(30) and
0.0023(30) Å, respectively). An analysis of the devia-
tions of the three outer rings from co-planarity with the
central ring shows a similar pattern to the un-substituted
triphenylene and thus atoms C2 C3 C7a C8 C9 and
C10a correspond to ring A, C1 C6 C15 C16 C17 and
C18a correspond to B, while C4 C5 C11a C12 C13
C14 correspond to C. The dihedral angles between the
central rings and the outer rings are 1.13(27), 2.14(28)
and 1.77(27)◦ to A, B and C, respectively. As far as
the metrical parameters are concerned, the central ring
shows the same pattern of alternating short and long
C-C bond lengths (1.464 vs 1.409 Å). In comparison
with the structure of triphenylene it can be seen that the
C-C bond lengths C11a C12 and C17 C18a (1.344(7)
and 1.355(7) Å) have been shortened from the corre-
sponding bonds (1.384(4) and 1.383(4) Å) due to the
Se substitution. As far as the packing is concerned it
appears that the substitution has not had a major effect
on the π − π stacking compared to the un-substituted
derivative.
to 13.3470(11) Å. There are similar but less dramatic
lengthening of both the a and c axes. Consequently
there is a significant increase in overall cell volume
from 1137.81(6) Å3 to 1178.14(14) Å3 and an increase
in overall crystal density from 1.333 to 1.463. Both
the central ring and three outer rings are planar (rms
deviations of 0.0033(14), 0.0033(14), 0.0026(16) and
0.0085(16) Å, respectively). An analysis of the devia-
tions of the three outer rings from co-planarity with the
central ring shows a similar pattern to the un-substituted
triphenylene and thus atoms C1 C6 C15a C16 C17 C18a
correspond to ring A, C4 C5 C11 C12 C13 C14A corre-
spond to B , while C2 C3 C7A C8 C9 C10 correspond to
C. The dihedral angles between the central rings and the
outer rings are 0.98(15), 1.94(15) and 2.07(15)◦ to A,
B and C, respectively. As far as the metrical parameters
are concerned the central ring shows the same pattern
of alternating short and long C-C bond lengths (1.464
vs. 1.409 Å). Otherwise there is very little difference
between the two LT structures. As far as the packing is
concerned, it appears that the substitution has not had
a major effect on the π − π stacking compared to the
un-substituted derivative (figures 3 and 4).
For the structure of the LT tellurium derivative
(3–26), the extent of substitution is very small (0.02)
but clearly seen in the NMR and MS data (vide supra).
In this case there is only one site seen in the struc-
ture analysis (figure 5). Unlike the other four structures,
this structure was collected with Mo radiation. The cell
constants are not significantly different from the un-
substituted derivative. Both the central ring and three
outer rings are planar (rms deviations of 0.0049(7),
0.0036(7), 0.0025(7) and 0.0064(7) Å, respectively).
An analysis of the deviations of the three outer rings
from co-planarity with the central ring shows a simi-
lar pattern to the un-substituted triphenylene and thus
atoms C5 C6 C15 C16 C17 C18 correspond to ring
A, C3 C4 C11 C12 C13 C14 correspond to B , while
C1 C2 C7 C8 C9 and C10 correspond to C. The dihe-
dral angles between the central rings and the outer
rings are 1.28(7), 2.11(7) and 2.53(7)◦ to A, B, and
The structure of the third Se derivative (3–24c) was
also carried out at 123 K and the extent of Se sub-
stitution was greater at 0.41 Se per triphenylene. As
in the LT derivative previously discussed, the substitu-
tion pattern shows two positions for the Se in an atom
ratio of 2.13:1. Since this structure was also carried
out at the same temperature as for the un-substituted
molecule a direct comparison of the effect on crys-
tal data can be made. As in the previous LT exam-
ple, the largest change in cell constants is for the b
axis where the length has changed from 12.9714(4)

Isolation and structures of some selenium and tellurium derivatives
1319
Figure 3. Packing diagram showing only 24 Se· · ·Se distance 3.291(3)Å, Se· · ·H distance
2.80 Å [1/2 + x, 1/2 -y, 1-z], Se· · ·Se· · ·Se angle 106.5(4)◦.
C, respectively. As far as the metrical parameters are difference between the substituted and un-substituted
concerned the central ring shows the same pattern of structures. As far as the packing is concerned it appears
alternating short and long C-C bond lengths (1.4625 that the substitution did not have a major effect on
vs. 1.4099 Å). Otherwise there is very little significant the π − π stacking compared to the un-substituted
Figure 4. Packing diagram of the co-crystallized triphenylene.

1320
Poonam Rajesh Prasad et al.
shorter than that observed for dimethoxytellurophene
(3.803–4.04 Å).25 As seen in the table of π . . . π Inter-
actions (table 1), there are very little significant differ-
ences in the packing between the un-substituted triph-
enylene and mono-Te derivative, reflecting the fact that
the overall structure has not been perturbed by the low
occupancy of Te (0.02). The perpendicular separation of
the central planes is 3.400(6) Å and the centroid to cen-
troid distance for both is 3.714(6) Å. For the RT struc-
ture (3–24a), there is increased separation of the planes
as well as centroid to centroid distances. For the two LT
Se structures (3–24b and 3–24c), again there is a minor
increase in interplanar separation.
4. Conclusion
Synthesis of organoselenium and –tellurium contain-
ing polyaromatic hydrocarbon derivatives has been
attempted. Due to the larger size of selenium and tel-
lurium, it is difficult to introduce them at the periph-
eral positions of triphenylene. Elemental analysis and
single crystal X-ray structure analysis of organosele-
nium compound indicates that these always synthesize
Figure 5. Molecular structure of 26: Selected bond (Å)
lengths and bond angles (◦): Te-C7 1.951(5), Te-C7 1.956(5),
C18-Te-C7 97.2(2).
derivative (figure 6). The packing diagram of molecule as a mixture of three components 3 and 24 and it is
3–26 shows Te· · · Te intermolecular interaction with too difficult to separate them. Similar, results were also
bond distances of 2.963(6) Å which are shorter than observed for the tellurium derivative 26 (3 and 26 mix-
the sum of van der Waals radii of Te (4.30 Å). The ture). Alongside, the synthesis of monoselenide 22 and
Te· · · Te bond distance (2.963(6) Å) is significantly selenocyanate 23 derivatives has been achieved.
Figure 6. Two-dimensional packing diagram of 26.

Isolation and structures of some selenium and tellurium derivatives
1321
10. Li X, Zhu Y, Shao J, Wang B, Zhang S, Shao Y, Jin X,
Yao X, Fang R and Shao X 2014 Angew. Chem. Int. Ed.
53 535
Supplementary Information
CCDC-1004393(3), CCDC-990989(3–24a), CCDC-99
0990(3–24b), CCDC-990991(3–24c), CCDC-990992
(3–26) contains the supplementary crystallographic
data for this paper. These data can be obtained free
of charge from The Cambridge crystallographic Data
Centre via www.ccdc.cam.ac.uk/data_request/cif.
11. Wei J, Jia X, Yu J, Shi X, Zhang C and Chen Z 2009
Chem. Commun. 4714
12. Sheldrick G M SHELXS-97, Program for Crystal Struc-
ture Solution University of Göttingen, 1997
13. Sheldrick G M SHELXL-97, Program for Crystal Struc-
ture Refinement; University of Göttingen, 1997
14. International Tables for X-ray Crystallography Vol 4
1974 (Birmingham: Kynoch Press)
15. Wei J, Gao Y, Ma X, Jia X, Shi X and Chen Z 2010
Chem. Commun. 46 3738
16. Selvakumar K, Singh H B, Goel N, Singh U P and
Acknowledgements
HBS is grateful to the Department of Science and
Technology (DST), New Delhi (India), for generous
funding. PRP is thankful to Department of Chemistry,
IIT Bombay for a teaching assistantship.
Butcher R J 2011 Dalton Trans. 40 9858
17. Panda A, Menon S C, Singh H B and Butcher R J 2001
J. Organomet. Chem. 62 87
18. Müller J and Terfort A 2006 Inorg. Chim. Acta 359
4821
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