A convenient synthesis of some symmetrical and unsymmetrical diarylmethyl sulfur and selenium compounds: X-ray crystal structure of diphenylmethylseleno-2-propene and bis[p-chlorophenyl(phenyl)methyl] diselenide

Article abstract of DOI:10.1016/j.jorganchem.2004.07.040

A number of novel and synthetically important symmetrical and unsymmetrical diarylmethyl sulfur and selenium compounds have been synthesized and characterized with the help of elemental analysis and various spectroscopic techniques. The methodology employ

Full text of DOI:10.1016/j.jorganchem.2004.07.040

Journal of Organometallic Chemistry 689 (2004) 3327–3334
www.elsevier.com/locate/jorganchem
A convenient synthesis of some symmetrical and unsymmetrical
diarylmethyl sulfur and selenium compounds: X-ray crystal
structure of diphenylmethylseleno-2-propene and
bis[p-chlorophenyl(phenyl)methyl] diselenide
a,
a
a
a
a
K.K. Bhasin *, Neelam Singh , Rajeev Kumar , D. Gupta Deepali , S.K. Mehta ,
b,
b
Thomas M. Klapoetke *, M.-J. Crawford
a
Department of Chemistry and Centre of Advanced Studies in Chemistry, Panjab University, Sector 14, Chandigarh 160 014, India
b
Department of Chemistry and Biochemistry, University of Munich, Butenandstr, 5–13 (D), D–81377 Munich, Germany
Received 11 June 2004; accepted 24 July 2004
Available online 11 September 2004
Abstract
A number of novel and synthetically important symmetrical and unsymmetrical diarylmethyl sulfur and selenium compounds
have been synthesized and characterized with the help of elemental analysis and various spectroscopic techniques. The methodology
employs sodium borohydride in ethanol–DMF for E–E bond cleavage (where E = S, Se) at room temperature and gives satisfactory
yield of the titled compounds. Molecular structure of bis[p-chlorophenyl(phenyl)methyl] diselenide (3) and diphenylmethylseleno-2-
ꢀ
propene 7 has been established with the help of single crystal X-ray analysis. The compound (3) is triclinic and crystallizes into P1
space group, whereas the compound 7 is monoclinic with P21/C space group.
ꢀ 2004 Elsevier B.V. All rights reserved.
Keywords: Diarylmethyl sulfide/selenide; Hydrazine hydrate; Sodium borohydride; X-ray crystal structure
1. Introduction
bersome synthetic methodologies, difficulty in purifica-
tion and unstable nature.
Diorganyl selenides are convenient starting materials
and excellent synthons in organic synthetic chemistry [1–
3]. Among these, the dialkyl selenides are important syn-
thetic targets and valuable precursors for the formation
of selenoxides (which undergo thermal or photochemi-
cal fragmentation offering routes to many useful and
selective functional group transformations). However,
despite their potential applications, their wide utilization
in diverse areas has largely been restricted due to cum-
In pursuance of our work on the aliphatic selenium
and tellurium compounds, we report herein, a conven-
ient and facile method for the synthesis of some de-
signed bis(diarylmethyl) dichalcogenides and their
unsymmetrical monochalcogen derivatives. Some of
the properties and decomposition behavior of these
compounds have also been discussed.
2. Results and discussion
*
Corresponding
+911722545074.
E-mail addresses: kkbhasin@pu.ac.in (K.K. Bhasin), tmk@wp.uni-
authors.
Tel.:
+911722541435;
fax:
The synthetic strategy which has been followed to
prepare bis(diarylmethyl) disulfides/diselenides, employs
hydrazine hydrate as the reducing agent [4]. It is
muenchen.de (T.M. Klapoetke).
0022-328X/$ - see front matter ꢀ 2004 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2004.07.040

3328
K.K. Bhasin et al. / Journal of Organometallic Chemistry 689 (2004) 3327–3334
preferred over sodium borohydride because the latter is
more expensive and non-selective reagent for the gener-
ation of dichalcogenide anions [5]. However, the ditellu-
ride could not be isolated through the same procedure
owing to its rapid detelluration, forming largely
1,1,2,2-tetraphenylethane as the coupled product. At-
tempts to prepare this compound at ꢀ30 to ꢀ40 ꢁC
using sodium metal as a reducing agent in liquid ammo-
nia [6] lead to a transient yellow colored compound
which decomposed prior to isolation. The instability of
bis(diarylmethyl) ditelluride can be explained on the ba-
sis of low bond dissociation energy of a sterically con-
strained aliphatic C–Te bond.
Initiation
Ar2CHSeR
h
or
Ar2CH
R2Se2
RSe
+
+
(1)
(2)
Propagation
RSe
Ar2CHSeR
Ar2CH
Ar2CH
+
R
+ Se
RSe
(3)
(4)
Ar2CHSeR
RSeR
+
R
+
Termination
Ar2CHCHAr2
R2Se2
2Ar2CH
2RSe
(5)
(6)
(7)
(8)
Ar2CH
+ R
+ R
Ar CHR Ar2CHCHAr2
+
+
2
R-R
RSe
RSeR
Scheme 2. Proposed mechanism of Ar2CHSeR decomposition.
A scrutiny of the literature shows only one reference,
on the synthesis of some unsymmetrical diphenylmethyl
selenium compounds, by Kamigata et al. [7]. In this pa-
per the authors have reported the formation of methyl
diphenylmethyl selenide (4) and benzyl diphenylmethyl
selenide (8) as side products in the reaction of 1,3-
bis(alkylseleno) allenes with diphenyl diazomethane.
We have also reported earlier, the synthesis of the corre-
sponding methoxymethyl and ethoxymethyl derivatives
[8]. In continuation with the work, we have successfully
synthesized a variety of unsymmetrical diarylmethyl
selenides and sulfides (II) starting from the dichalcoge-
nides (I), as shown in the Scheme 1. In this methodology
ethanolic sodium borohydride [9] has been used for the
reductive cleavage of dichalcogenide bond (E–E) at room
temperature. Dimethyl formamide has been employed as
a co-solvent in this reaction. Addition of DMF improves
the yield by solubilizing the diarylmethyl chalcogenolate
anion, which is otherwise known to exist as boron com-
plex possessing diminished nucleophilicity [10].
conducted by Chu et al. [11,12] on the thermal and pho-
tochemical decomposition behavior of dibenzyl disele-
nide and bis(diphenylmethyl) diselenide reveal
a
radical mechanism involving C–Se and Se–Se bond scis-
sion. A similar analogy can be drawn to comprehend the
decomposition behavior of unsymmetrical alkyl diphe-
nylmethyl selenides (Ph2CHSeR). The primary process
is presumed to involve the homolytic cleavage of C–Se
bond towards diphenylmethyl carbon (Scheme 2).
The preferential cleavage of C–Se bond towards
diphenylmethyl carbon can be reasonably attributed to
the electron delocalization rendered possible by the
phenylation of carbon which confers extra stability to
the diphenylmethyl radical. The poor stability of C–Se
bond may further be discerned from the extensive steric
crowding around the selenium atom. On the basis of the
products obtained one can say that Eqs. (5) and (6) are
major termination pathways.
The various compounds prepared have been charac-
terized through elemental analysis and different spectro-
scopic techniques viz. NMR (1H, 13C, 77Se, 19F), FT-IR,
UV–Vis spectroscopy and mass spectrometry.
It is an interesting observation that most of the n-al-
kyl diphenylmethyl selenides prepared, undergo decom-
position over a period of time to form lower symmetrical
diselenide of primary alkyl group and 1,1,2,2-tetraphe-
nyl ethane with traces of elemental selenium. Studies
An attempt to synthesize the bivalent and tetravalent
diarylmethyl selenium compounds was not successful
through oxidative halogenation of mono- and disele-
nides. Instead, it resulted in the scission of C–Se bond
and diarylmethyl halide was recovered back (Scheme
3). Secondary and tertiary unsymmetrical dialkyl sele-
nides are known to undergo conversion into the corre-
sponding alkyl halides and diselenide of the primary
alkyl group [13,14]. We found that the halogenation of
Ar
CHCl
Ar
Ar
CH-E-E-CH
E2-
N2H4.H2O / NaOH
Ar'
2E
2
DMF, r.t.
Ar'
Ar'
(I)
Ar
Ar
Ar
-
(i) NaBH / C H OH DMF
, r.t.
4
2 5
CH-E-R
CH-E-E-CH
Ar'
o
(ii)RX,
0 - 5 C
Ar'
Ar'
(II)
(I) E = S, Ar = Ar' = C6H5 (1); E = Se, Ar = Ar' = C6H5 (2), Ar = C6H5, Ar' = p-ClC6H4 (3); (II) E = Se, Ar = Ar' =
C6H5; R = CH3 (4), C2H5 (5), n-C4H9 (6), CH2CH=CH2 (7), CH2C6H5 (8), CH2CF3 (9), C10H7 (10); Ar = C6H5, Ar' =
p-C6H4Cl; R = C2H5 (11), CH2CH=CH2 (12); E = S, Ar = Ar' = C6H5; R = C2H5 (13), CH2CH=CH2 (14); X = Br, Cl.
Scheme 1. Reaction scheme for the synthesis of some unsymmetrical diarylmethyl selenides and sulfides.

K.K. Bhasin et al. / Journal of Organometallic Chemistry 689 (2004) 3327–3334
3329
Ar
Ar
CH-Se-Se-CH
The role of a chloro substituent at the para positon of
the phenyl ring in redistributing the electron density of
the ring protons is apparent but not very pronounced.
A marginal downfield shift is observed in the p-chloro
analogues. In case of 9 and 10 the methine carbon is
exceptionally deshielded due to the withdrawl of r-elec-
trons by trifluoromethyl group and naphthyl ring,
respectively. 13C NMR spectroscopic results reveal a
similar trend, signals corresponding to ipso-carbon ap-
pear most downfield (139–142 ppm). Other aromatic
carbons fall in the region of ca. 126–140 ppm. The chem-
ical shift value of methine carbon is about 51 ppm
in case of diselenides and ca. 60 ppm in disulfide. In
unsymmetrical monoselenides the absorption occurs in
the range of 46–48 ppm. The mass spectrum is rich
and complicated due to several isotopes of selenium.
For most compounds analyzed the molecular ion peak
is either very weak or absent. The fragment correspond-
ing to the mass of diarylmethyl radical is most intense
and appears at m/e 167 or 202 depending on the aryl
substitutents and is assigned the base value. The frag-
ment ions containing selenium show a highly character-
istic and definite pattern of signal intensities depending
on the natural abundance of various isotopes of
selenium.
Ar
SOCl2 or Br2,
- 10˚C
CH-X + Se
CH2Cl2 or CHCl3
Ar'
Ar'
Ar'
Ar
Ar
SOCl2 or Br2, - 10˚C
CH2Cl2 or CHCl3
CH-Se-R
CH-X + 1/2 R2Se2
Ar'
Ar'
Scheme 3. Halogenation of diphenylmethyl di- and mono-selenides.
n-alkyl diarylmethyl selenides (R = methyl, ethyl, butyl
etc.) under similar conditions affords diarylmethyl ha-
lides and dialkyl diselenide (R2Se2). We assume that
the reaction takes place via the formation of electrophi-
lic alkyl selenium species (see Scheme 4).
2.1. Spectroscopic studies
As evident from the NMR data selenium exerts a
greater deshielding effect than sulfur, particularly on a-
H atoms. The resonance signals of methine protons in
all the unsymmetrical diarylmethyl selenides (Ar2CH-
SeR) show a downfield shift of 0.11–0.21 ppm relative
to a-H of the corresponding bis(diarylmethyl) disele-
nide. Nevertheless, the signals appear upfield w.r.t. the
methine proton of diarylmethyl chloride (0.7–1.1
ppm). In the 1H NMR of diphenylmethyl selenides,
the absorption signals of aromatic protons display three
different sets, two of which are multiplets and the third
one, corresponding to the hydrogen at para position, ap-
pears as a triplet of triplets.
An evaluation of the 77Se NMR spectra gives a signif-
icant insight into the distribution of electron density
around selenium metal center. Resonance occurs in the
region 259–423 ppm in case of various unsymmetrical
diarylmethyl selenides and is sensitive to the variation
of substituents on the a-carbon of alkyl group.
The comparison of spin–spin coupling interactions in
allylic derivatives [7, 12 and 14] shows that the magni-
tude of trans-3JH–H coupling constant of the terminal
hydrogen is same in all the three compounds i.e., 16.8
Hz and is much stronger than the cis-3JH–H coupling
interaction (which is respectively, 9.6, 10.2 and 9.9 Hz
for the compounds 7, 12 and 14. The hydrogen cis
w.r.t vicinal hydrogen experiences greater deshielding
than the trans hydrogen. In all the cases, the magnitude
of coupling constant was found to be consistent with the
reported J values in allylic systems [15].
2.2. X-ray discussion
To have an understanding of the structural details,
single crystal X-ray diffraction of 3 and 7 was carried
out. A perspective view and atom numbering scheme
of these compounds is given in Fig. 1 and the important
bond parameters are listed in Table 1. As observed from
the crystallographic data, the geometry of 3 is compara-
ble to 2 given in the literature [16]. The average Se–Se
bond distance shows quite normal value. However, the
˚
C–Se bond is slightly longer [2.015(4) and 1.995(4) A]
˚
than the expected bond length (1.93–1.97 A). Unlike
few other sterically hindered diselenides [17], the C–
Se–Se–C dihedral angle is acute [82.62(18)] and close
to the theoretical value [18] of 90ꢁ which means that
the steric strain is being relieved through bond lengthen-
ing rather than widening up of dihedral angle. One com-
mon observation in both the crystal structures is that,
one of the aryl rings (phenyl or p-chlorophenyl) is more
closely disposed towards the selenium atom than the
other. However, it is evident from the interatomic bond
distance comparisons that there are no inter- or intra-
molecular non-bonded contacts within the crystal lat-
tice. As expected, there is an observed distortion in the
X
Ar
Ar
+
Ar'
CH
Se
X
R
RSeX
CH-X
Ar'
Ar
Ar
CH Se-R
RSe+X -
CH-X
R2Se2
+
Ar'
Ar'
Scheme 4. Proposed pathway for the halogenation of unsymmetrical
alkyl diphenylmethyl selenides.

3330
K.K. Bhasin et al. / Journal of Organometallic Chemistry 689 (2004) 3327–3334
Fig. 1. ORTEP diagram showing the conformation and atom numbering scheme for bis[p-chlorophenyl (phenyl)methyl]diselenide (3) and
diphenylmethylseleno-2-propene (7).
Table 1
Selected bond parameters of 3 and 7
˚
Bond length (A)
Bond angle (ꢁ)
Torsional angle (ꢁ)
Compound (3)
Se(1)–C(1)
2.015(4)
2.3043(7)
1.995(4)
1.742(5)
C(1)–Se(1)–Se(2)
C(14)–Se(2)–Se(1)
C(8)–C(1)–C(2)
C(8)–C(1)–Se(1)
101.31(12)
103.88(11)
117.8(4)
C(1)–Se(1)–Se(2)–C(14)
Se(2)–Se(1)–C(1)–C(8)
Se(2)–Se(1)–C(1)–C(2)
Se(1)–Se(2)–C(14)–C(15)
82.62(18)
ꢀ58.8(3)
172.6(2)
64.5(3)
Se(1)–Se(2)
Se(2)–C(14)
Cl(1)–C(5)
110.5(3)
Compound (7)
Se(1)–C(1)
1.965(3)
1.957(3)
1.512(4)
1.397(5)
1.359(7)
1.293(5)
C(1)–Se(1)–C(14)
Se (1)–C(1)–C(2)
Se(1)–C(1)–C(8)
Se(1)–C(14)–C(15)
C(14)–C(15)–C(16)
C(8)–C(1)–C(2)
97.79(13)
106.16(17)
115.6(2)
110.4(3)
125.9(4)
113.5(2)
C(13)–C(8)–C(1)–C(2)
C(8)–C(1)–C(2)–C(7)
ꢀ89.7
Se(1)–C(14)
C(1)–C(2)
ꢀ137.9
C(12)–C(13)
C(10)–C(11)
C(15)–C(16)
tetrahedral distribution of bond angles around methine
carbon in both cases.
In compound 7, the Se(1)–C(1) and Se(1)–C(14) bond
(phenyl)methyl chloride (Aldrich) were newly purchased
and stored in a dessicator prior to use. Diphenylmethyl
chloride [20] and 1,10-dinaphthyldiselenide [21] were pre-
pared by literature method. All other chemicals were of
analytical grade and used without further purification.
Ethanol was freshly distilled and dehydrated under
sodium metal. Other solvents were also purified by
standard methods. Melting points were uncorrected.
Separation and purification of the compounds was done
by column chromatography performed on activated sil-
ica gel (230–400) using hexane as eluant.
1H, 13C NMR spectra were recorded in CDCl3 using
Me4Si as an internal standard on JEOL AL 300Mz spec-
trometer. 77Se and 19F NMR were reported on the same
instrument using Me2Se and CFCl3, respectively, as an
external reference. UV–Vis spectral analysis was per-
formed on JASCO V-530 UV–Vis spectrophotometer.
Infrared spectra were obtained either between KBr pel-
lets as neat liquids or as compressed KBr discs in case of
solid compounds, on a Perkin–Elmer model 1430 spec-
trophotometer. X-ray diffraction data were collected
separately on a Siemens P4 and Nonius MACH3 diffrac-
tometer. Elemental analysis was performed on a Perkin–
Elmer 2400 CHN analyzer. The mass spectra were
obtained on a VG-70S 11-250J mass spectrometer.
˚
lengths are 1.965(3) and 1.957(3)A, respectively, which
are normal and identified as aliphatic C–Se bonds. The
ring [C(8)–C(13)] indicates a small degree of distortion
from normal benzene configuration, both in terms of
planarity and distribution of bond lengths and bond an-
gles, as evidenced by a slight deviation for C(10)–C(11),
C(12)–C(13) bond lengths and C(13)–C(8)–C(9), C(10)–
C(9)–C(8) bond angles. Nevertheless, both the rings can
be considered to be aromatic and planar within experi-
mental error and this distortion is presumed to arise
from different environments around the two rings in
the crystal. All other bond parameters show quite nor-
mal values.
3. Experimental
All the reactions were carried out under dry and
deoxygenated nitrogen atmosphere. Selenium/tellurium
were estimated by standard methods [19]. Sodium boro-
hydride (Loba), selenium (Hi-media), elemental sulfur
(Aldrich), tellurium (Aldrich) and p-chlorophenyl

K.K. Bhasin et al. / Journal of Organometallic Chemistry 689 (2004) 3327–3334
3331
3.1. General procedure for the synthesis of bis(diaryl-
methyl) diselenides/disulfides
methane after evaporating ethanol under vacuum. The
organic layer is washed repeatedly with distilled water
(3 · 40 ml), dried over anhydrous Na2SO4. Solvent is
evaporated on a rota-evaporator and the product is sub-
jected to purification on a silica column using hexane as
the eluant.
To a vigorously stirred mixture of powdered sodium
hydroxide (3.0 g, 75 mmol), elemental chalcogen
(S = 1.6 g or Se = 4.0 g, 50 mmol) and dimethylforma-
mide (30 ml), 100% hydrazine hydrate was added slowly.
After stirring for nearly 6 h at room temperature, a solu-
tion of diarylmethyl chloride (100 mmol) dissolved in 15
ml DMF was added dropwise.When the color of solu-
tion became light yellow, it was diluted with about 250
ml of distilled water and extracted in dichloromethane
(3 · 50 ml). The organic layer was washed with 6N
HCl followed by distilled water and then dried over
anhydrous sodium sulfate. The solution was decanted
and solvent evaporated to get the crude compound in
solid form.The product was purified through recrystalli-
zation by dissolving in 5% ethylacetate–hexane.
3.3. Procedure for the synthesis of 10
To a vigorously stirred mixture of 1,10-dinaphthyl
diselenide (2.07 g, 5 mmol) and powdered NaOH (1.0
g, 25 mmol) in DMF (30 ml) was added a solution of
hydrazine monohydrate (0.3 ml, 6 mmol) in DMF under
nitrogen at room temperature. After 2–3 h of stirring,
the color of reaction mixture turns pale yellow from or-
ange red. The reaction mixture was then cooled to ꢀ10
ꢁC and a solution of diphenylmethyl chloride (1.77 ml,
10 mmol) diluted with equal volume of DMF is added
slowly dropwise and stirring continued until the reaction
was complete. Extraction was done as in 3.1 and the
product was purified on a silica column using hexane
as eluant.
3.2. General procedure for the synthesis of unsymmetrical
diarylmethyl selenides/sulfides
To a 5 mmol solution of bis(diarylmethyl) diselenide/
disulfide in 50 ml C2H5OH–DMF (3:2) was added 0.456
gm (12 mmol) of NaBH4 in parts with continuous stir-
ring at room temperature. After 3 h of stirring, 10 mmol
of the alkylating agent (RX) diluted with equal volume
of DMF was added dropwise at 0–5 ꢁC. Reaction was
complete within 1–2 h. Extraction is done in dichloro-
3.4. X-ray studies
Diffraction quality single crystals of 3 and 7 were
obtained by the slow evaporation of 5% ethylace-
tate–hexane solution of the compounds. Yellow plate
like crystals of 3 were formed in two days. Colorless
Table 2
Crystallographic data and measurements of 3 and 7
Compound 3
Compound 7
Empirical formula
Formula Weight (g/mol)
Temperature (K)
C26H20Cl2Se2
561.24
C16H16Se
287.25
293 (2)
293(2)
Nonius MACH3
Diffractometer used
Siemens P4
Mo Ka, 0.17073
Monoclinic, P21/C
˚
Radiation used, wavelength (A)
Crystal systems, space group
Unit cell dimensions
Mo Ka, 0.70930
ꢀ
Triclinic, P1
˚
a (A)
9.3750(14)
9.9780(8)
12.7900(8)
100.598(6)
90.188(8)
94.062(9)
1172.9(2)
2, 1.589
3.391
8.815(1)
22.355(1)
7.421(1)
90
˚
b (A)
˚
c (A)
a (ꢁ)
b (ꢁ)
c (ꢁ)
108.08 (1)
90
3
˚
Volume (A )
1390.2 (3)
4, 1.372
2.677
Z, calculated density (Mg/m3)
Absorption coefficient (mmꢀ1
F (0 0 0)
)
556
584
Crystal size
Index ranges
0.40 · 0.20 · 0.15 mm
0.22 · 0.17 · 0.16 mm
0 6 h 6 11,ꢀ11 6 k 6 11,15 6 l 6 15
3726/3726 [Rint = 0.0000]
Full-matrix least-squares on F2
R1 = 0.0433, xR2 = 0.1055
R1 = 0.0513, xR2 = 0.1147
1.227 and ꢀ0.924
ꢀ10 < h < 9,0 < k < 25,0 < l < 8
2369/2161 [Rint = 0.0311]
Full-matrix least-squares on F2
R1 = 0.0355, xR2 = 0.0767
R1 = 0.0502, xR2 = 0.0813
0.308 and ꢀ0.291
Reflection collected/unique
Refinement method
Final R indices, [I > 2r(I)]
R indices [all data]
ꢀ3
˚
Largest difference peak and hole (e A
)

3332
K.K. Bhasin et al. / Journal of Organometallic Chemistry 689 (2004) 3327–3334
cubical crystals of 7 were formed upon cooling satu-
rated solution of this compound. Suitable crystals
were chosen from a crop of crystals and mounted
on glass fibres and data sets were collected on a
Nonius MACH3 diffractometer in case of 3 and Sie-
mens P4 diffractometer in case of 7 for the cell deter-
mination and intensity data collection. The diffraction
data were collected using monochromatic Mo Ka
radiation at 293(2) K. The detail of crystal structure
determination and refinement parameters is given in
Table 2.
The unit cell parameters were derived and refined by
using randomly selected reflections in 2h range 1.62–
24.92 in 3 and 1.82–24.00 in 7. Crystal structure was
solved by direct method (SHELX-97) [22] and refined by
full-matrix least-squares method. Anisotropic thermal
parameters were employed for non-hydrogen atoms.
All the hydrogen atoms were geometrically fixed and al-
lowed to refine using a riding model.
3.4.2. Unsymmetrical alkyl diarylmethyl selenides/
alkyldiphenylmethyl sulfides
3.4.2.1. Methylselenodiphenylmethane, [Ph2CHSeCH3]
(4). Yield = 58%, pale yellow waxy solid, m.p. = 38–
1
45 ꢁC, H NMR: d 7.35–7.38 (m, 4H), 7.21–7.26 (m,
4H), 7.12–7.17 (tt, 2H), 5.25 (s, 1H), 1.79 (s, 3H); 13C
NMR: d 141.55, 128.82, 128.52, 126.99, 48.81, 6.22;
77Se–NMR: d 259.5; IR (KBr, cmꢀ1): 3026.0, 3001.5,
2923.7, 1375.3, 1448.7, 580.4, 624.0; MS-EI (m/e, R.I.,
assignment): 262 (0.2, [M]+), 247 (0.6, [Ph2CHSe]+),
167 (100, [Ph2CH]+). Anal. Calc. for C14H14Se: C,
78.39; H, 5.52. Found: C, 77.96; H, 5.32%.
3.4.2.2. Ethylselenodiphenylmethane, [Ph2CHSeCH2-
CH3] (5). Yield = 65%, yellow oil, 1H NMR: d
7.26–7.30 (m, 4H), 7.11–7.16 (m, 4H), 7.00–7.06 (tt,
2H), 5.26 (s, 1H), 2.20–2.31 (q, 2H, 7.5 Hz), 1.19–1.25
(t, 3H, 7.5 Hz); 13C NMR: d 141.79, 128.84, 128.46,
126.90, 47.30, 19.20, 15.36; 77Se–NMR: d 376.7; IR
(KBr, cmꢀ1): 3083.3, 3059.9, 3024.9, 2956.3, 2922.7,
2865.6, 1598.8, 1582.4, 1493.2, 1448.0, 964.9, 623.8,
581.0. Anal. Calc. for C15H16Se: C, 65.21; H, 5.79.
Found: C, 65.45; H, 5.38%.
3.4.1. Symmetrical bis(diarylmethyl) dichalcogenides
3.4.1.1. Bis(diphenylmethyl) disulfide, [(C6H5)2CHS]2
(1). Yield = 77%,
colorless
crystalline
solid,
1
m.p. = 153–154 ꢁC, H NMR: d 7.29 (s, 20H), 4.78 (s,
2H); 13C NMR: d 140.26, 129.04, 128.52, 127.56,
59.77; IR (KBr, cmꢀ1): 3082.4, 3055.5, 3024.5, 1585.1,
1490.1, 1447.2, 1079.9, 1027.1, 748.1, 719.3, 623.5,
585.9, 525.3; MS-EI, m/e (R.I., assignment): 231(0.1,
[Ph2CHS2]+), 199 (3.7, [Ph2CHS]+), 167 (100,
[Ph2CH]+), 91 (0.9, [PhCH2]+); UV–Vis: (C2H5OH, kmax
nm): 271, 243; (CH3CN, kmax nm): 397, 310, 272. Anal.
Calc. for C26H22S2: C, 78.39; H, 5.52. Found: C, 77.96;
H, 5.32%.
3.4.2.3. n-Butylselenodiphenylmethane, [Ph2CHSeC4H9]
1
(6). Yield = 65%, yellow oil, H NMR: d 7.25–7.29
(m, 4H), 7.08–7.14 (m, 4H), 6.97–7.03 (tt, 2H), 5.22 (s,
1H), 2.20–2.25 (t, 2H, 7.5 Hz), 1.38–1.48 (m, 2H),
1.13–1.26 (m, 2H), 0.69–0.74 (t, 3H, 7.2 Hz); 13C
NMR: d 141.87, 128.83, 128.44, 126.88, 47.55, 32.13,
25.15, 23.15, 13.82; 77Se–NMR: d 344.5; IR (KBr,
cmꢀ1): 3025.1, 3001.3, 2956.5, 2925.9, 2870.4, 1493.5,
1378.0, 1448.3, 623.5, 580.3. Anal. Calc. for C17H20Se:
C, 67.10; H, 6.57. Found: C, 66.84; H, 6.12%.
3.4.1.2. Bis(diphenylmethyl) diselenide, [(C6H5)2-
CHSe]2 (2). Yield = 85%, pale yellow crystalline so-
lid, m.p. = 122–123 ꢁC, 1H NMR: d 7.22–7.34 (m,
20H), 5.04 (s, 2H); 13C NMR: d 141.29, 129.20, 128.40
127.23, 51.70; 77Se–NMR: d 522.2; IR (KBr, cmꢀ1):
3082.6, 3054.9, 3023.7, 1026.3, 999.7, 750.3, 696.7,
613.2, 578.7, 475.0; MS-EI, m/e (R.I., assignment): 247
(0.6, [Ph2CHSe]+), 167 (100, [Ph2CH]+), 91 (2.8,
[PhCH2]+). Anal. Calc. for C26H22Se2: C, 63.15; H,
4.45. Found: C, 63.02; H, 4.33%.
3.4.2.4. Allylselenodiphenylmethane, [Ph2CHSeCH2-
CH@CH2] (7). Yield = 70%, colorless crystalline so-
lid, m.p. = 46–47 ꢁC; 1H NMR: 7.40–7.43 (m, 4H),
7.21–7.26 (m, 4H), 7.11–7.17 (tt, 2H), 5.78–5.92 (m,
1H), 5.32 (s, 1H), 4.91–4.94 (d, 1H, 9.6 Hz), 4.68–4.75
(dd, 1H, 16.8 Hz, 2.4 Hz), 2.86–2.89 (d, 2H, 7.5 Hz);
13C NMR: d 141.21, 134.65, 128.84, 128.29, 126.73,
116.17, 47.18, 27.97; 77Se–NMR: d 366.6; IR (KBr,
cmꢀ1): 3062.4, 3026.7, 2924.5, 2853.6, 1493.5, 1427.5,
1628.0, 624.4, 580.0; MS-EI, m/e (R.I., assignment):
288(0.1, [M]+), 247 (0.6, [Ph2CHSe]+), 207 (0.6, [M-
Se]+), 167 (100, [Ph2CH]+). Anal. Calc. for C16H16Se:
C, 66.66; H, 5.55. Found: C, 67.31; H, 5.62%.
3.4.1.3. Bis[p-chlorophenyl(phenyl)methyl] diselenide,
[p-ClC6H4(C6H5)CHSe]2 (3). Yield = 86%, yellow
crystalline solid, m.p. = 110–111 ꢁC; 1H NMR: 7.15–
7.30 (m, 18H), 4.96 (s, 2H); 13C NMR: d 140.74,
139.53, 133.39, 130.43, 129.64, 128.72, 128.66, 127.63,
51.08; 77Se–NMR: d 525.1; IR (KBr, cmꢀ1): 2925.4,
2854.4, 1487.9, 1216.0, 1083.2, 1012.7, 642.6, 598.0,
497.0; MS-EI (m/e, R.I., assignment): 282 (0.7,
[C13H10SeCl]+), 202 (100, [C13H10Cl]+). Anal. Calc. for
C26H20Se2Cl2: C, 55.41; H, 3.55. Found: C, 54.82; H,
3.24%.
3.4.2.5. Benzylselenodiphenylmethane, [Ph2CHSeCH2-
Ph] (8). Yield = 75%, colorless crystalline solid,
m.p. = 51–52 ꢁC; 1H NMR: 7.31–7.34 (d, 4H), 7.04–
7.29 (m, 11H), 5.15 (s, 1H), 3.47 (s, 2H); 13C NMR: d
141.34, 138.99, 129.12, 129.07, 128.54, 128.37, 127.01,
126.70, 47.96, 29.56; 77Se–NMR: d 422.5; IR (KBr,
cmꢀ1): 3027.9, 2926.4, 2854.2, 1419.8, 1451.0, 626.1,

K.K. Bhasin et al. / Journal of Organometallic Chemistry 689 (2004) 3327–3334
3333
580.2. Anal. Calc. for C19H18Se: C, 71.00; H, 5.32.
Found: C, 71.86; H, 5.22%.
(m, 4H), 7.12–7.19 (m, 4H), 7.03–7.08 (tt, 2H), 5.01 (s,
1H), 2.22–2.24 (q, 2H, 7.5 Hz), 1.07–1.12 (t, 3H, 7.5
Hz); 13C NMR: d 141.58, 128.453, 127.051, 53.96,
26.17, 14.33; FT-IR (KBr, cmꢀ1): 3060.6, 3026.0,
2965.9, 2870.3, 1599.7, 1493.7, 1449.1, 1030.3, 1002.3,
749.1, 700.9, 628.8, 585.9, 506.6. Anal. Calc. for
C15H16S: C, 78.94; H, 7.01. Found: C, 78.26; H, 6.98%.
3.4.2.6. 2,2,2-Trifluoroethylselenodiphenylmethane, [Ph2-
CHSeCH2CF3] (9). Yield = 70%, golden yellow oil,
1H NMR: d 7.42–7.45 (m, 4H), 7.26–7.31 (m, 4H),
7.18–7.23 (tt, 2H), 5.62 (s, 1H), 2.71–2.82 (q, 2H, 10.6
Hz); 13C NMR: d 139.82, 128.74, 128.72, 127.57, 126.4
(q, ꢀ279.3 Hz; d 120.9, 124.6, 128.2, 131.8), 48.59,
25.6 (q, 32.9 Hz; d 24.9, 25.4, 25.8, 26.2);77Se–NMR:
313.3; FT-IR (KBr, cmꢀ1): 3062.8, 3028.7, 2925.1,
2854.2, 1749.0, 1599.6, 1494.3, 1450.0, 1290.4, 1259.5,
1031.6, 631.4, 581.4, 518.1; 19F NMR: d ꢀ 63.83 (triplet,
7.63 Hz). Anal. Calc. for C13H13SeF3: C, 50.98; H, 4.24.
Found: C, 49.86; H, 4.00%.
3.4.2.11.
Allylthiodiphenylmethane,
[Ph2CHSCH2-
CH@CH2] (14). Yield = 80%, colorless crystalline
1
solid, m.p. = 44–45 ꢁC; H NMR: 7.27–7.29 (m, 4H),
7.15–7.20 (m, 4H), 7.06–7.11 (tt, 2H), 5.65–5.75 (m,
1H), 4.98–5.01 (d, 2H, 9.9 Hz), 4.97 (s, 1H), 4.84–4.90
(dd, 1H, 16.8 Hz, 1.8 Hz), 2.87–2.89 (d, 2H, 6.9 Hz);
13C NMR: d 141.28, 134.25, 128.74, 128.55, 127.16,
117.29, 52.85, 35.14; FT-IR (KBr, cmꢀ1): 3084.9,
3064.1, 3028.2, 2916.9, 1635.7, 1599.8, 1494.7, 1450.1,
1031.1, 990.2, 630.4, 585.5, 504.8. Anal. Calc. for
C16H16S: C, 80.00; H, 6.66. Found: C, 79.96; H, 6.34%.
3.4.2.7. 1-Naphthylselenodiphenylmethane, [Ph2CHSe-
C10H7] (10). Yield = 70%, pale yellow crystalline so-
1
lid, m.p. = 70–71 ꢁC, H NMR: d 8.39–8.41 (d, 1H, 8.4
Hz), 7.72– 7.75 (d, 1H, 8.1 Hz), 7.66–7.69 (d, 1H, 8.4
Hz), 7.39–7.50 (m, 3H), 7.23–7.29 (m, 4H), 7.08–7.20
(m, 7H), 5.54 (s, 1H); 13C NMR: d 141.52, 134.91,
134.60, 134.04, 129.00, 128.85, 128.65, 128.40, 128.24,
128.11, 127.03, 126.68, 126.06, 125.64, 52.69; UV–Vis
(C2H5OH, kmax): 287, 319, 327 nm; (CH3CN, kmax):
327 nm; 77Se–NMR: d 407.2; FT-IR (KBr, cmꢀ1):
3029.1, 3058.4, 2924.5, 2853.9, 1654.3, 1599.6, 1494.1,
1449.3, 1031.3, 962.1, 616.4, 581.1. Anal. Calc. for
C21H18Se: C, 72.00; H, 5.14. Found: C, 71.86; H, 4.98%.
4. Supplementary material
Crystallographic information (excluding structure
factors) have been deposited in the CIF (Crystallo-
graphic Information File) format with the Cambridge
Crystallographic Data Centre as supplementary publica-
tion No. CCDC 234297 and 190931 for the compounds
(3) and (7), respectively. Copies of this information may
be obtained free of charge from the Director, CCDC, 12
Union Road, Cambridge CB21E2, UK (fax: +44-1223-
336033; e-mail: deposit@ccdc.cam.ac.uk).
3.4.2.8. Ethylseleno(p-chlorophenyl)phenylmethane, [(p-
ClC6H4)C6H5CHSeCH2CH3] (11). Yield = 60%, yel-
low oil, 1H NMR: d 7.21–7.27 (m, 4H), 7.05–7.17 (m, 5H),
5.22 (s, 1H), 2.22–2.29 (q, 2H, 7.5 Hz), 1.18–1.23 (t, 3H,
7.5 Hz); 13C NMR: d 141.12, 140.25, 132.68, 129.94,
128.59, 128.54, 128.47, 127.02, 46.33, 19.22, 15.18; FT-
IR (KBr, cmꢀ1): 3061.2, 3024.5, 2895.3, 1577.0, 1468.4,
1413.6, 602.7, 512. Anal. Calc. for C15H15SeCl: C,
57.97; H, 3.86. Found: C, 57.24; H, 3.23%.
Acknowledgements
The financial assistance from CSIR, New Delhi, vide
sanction No. 01(1865)/03/EMR-II, 2003 is gratefully
acknowledged. We are also thankful to Prof. P. Mathur,
Indian Institute of Technology, Mumbai, India and Dr.
P. Venugopalan, Panjab University, Chandigarh (India)
for doing the X-ray crystal analysis of our compounds.
K.K.B. is thankful to the German Academic Exchange
Service (DAAD) for a study and research visit to the
Federal Republic of Germany.
3.4.2.9. Allylseleno(p-chlorophenyl)phenylmethane, [(p-
ClC6H4)C6H5CHSeCH2CH@CH2]
(12). Yield =
68%, white crystalline solid, m.p. = 41–42 ꢁC; 1H
NMR: d 7.28–7.38 (m, 4H), 7.18–7.25 (m, 4H), 7.11–
7.16 (m, 1H), 5.75–5.90 (m, 1H), 5.21 (s, 1H), 4.91–
4.95 (d, 1H, 10.2 Hz), 4.75–4.80 (d, 1H, 16.8 Hz),
2.93–2.95 (d, 2H, 7.5 Hz); 13C NMR: d 140.81, 139.96,
134.57, 132.72, 130.24, 128.87, 128.66, 128.61, 127.18,
116.56, 46.43, 28.28; FT-IR (KBr, cmꢀ1): 3084.4,
2924.5, 1632.7, 1597.6, 1488.8, 1451.2, 1428.0, 1014.9,
988.4, 756.2, 719.1, 601.3, 505.3; 77Se–NMR: d 368.2.
Anal. Calc. for C16H15SeCl: C, 59.53; H, 4.65. Found:
C, 58.76; H, 4.38%.
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3334
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