Halogenation of dibenzoselenophene and dibenzo[1,2]diselenine

Article abstract of DOI:10.1002/zaac.201000135

The syntheses of the selenium containing heterocycles di-benzoselenophene (1 ≡ biphenSe) and dibenzo[1,2]diselenine (2 ≡ biphenSe₂) were optimized. The halogenation reactions of 1 and 2 with XeF₂, SO₂Cl₂, Br₂ and I₂ were performed and the corresponding products characterized. In the case of 1, the selenium(IV) dihalogenides, biphenSeF₂ (3), biphenSeCl₂ (4), biphenSeBr₂ (5), and the adduct biphenSe·I₂ (6), were isolated and identified. The extremely sensitive selenium(IV) difluoride 3 slowly formed significant amounts of an adduct with HF of the corresponding selenium(IV) oxide biphen-SeO·HF (3a) upon storage in glass vessels at low temperatures. In the case of 2, the selenium(IV) trihalogenides, biphen(SeHal₃)₂ (Hal = F, Cl, Br), were found to be extremely labile (Hal = F) or not detectable (Hal = Cl, Br). Instead, as decomposition products, the selenium chloride species Se₂Cl ₂, SeCl₄ and 1 were detected. In the case of Hal = I, the stable adduct biphenSe₂·I₂ (7) was isolated. In addition to characterization by multinuclear NMR spectroscopy, several molecular structures of biphen-selenium substituted halogenides were determined.

Full text of DOI:10.1002/zaac.201000135

ARTICLE
DOI: 10.1002/zaac.201000135
Halogenation of Dibenzoselenophene and Dibenzo[1,2]diselenine
Thomas M. Klapötke,[a] Burkhard Krumm,*[a] and Matthias Scherr[a]
Dedicated to Professor Rolf Minkwitz on the Occasion of His 70th Birthday
Keywords: Dibenzoselenophene; Dibenzo[1,2]diselenine; Selenium; Multinuclear NMR spectroscopy; X-ray diffraction
Abstract. The syntheses of the selenium containing heterocycles di- SeO·HF (3a) upon storage in glass vessels at low temperatures. In the
benzoselenophene (1 ≡ biphenSe) and dibenzo[1,2]diselenine (2 ≡ case of 2, the selenium(IV) trihalogenides, biphen(SeHal3)2 (Hal = F,
biphenSe2) were optimized. The halogenation reactions of 1 and 2 with Cl, Br), were found to be extremely labile (Hal = F) or not detectable
XeF2, SO2Cl2, Br2 and I2 were performed and the corresponding pro- (Hal = Cl, Br). Instead, as decomposition products, the selenium chlo-
ducts characterized. In the case of 1, the selenium(IV) dihalogenides, ride species Se2Cl2, SeCl4 and 1 were detected. In the case of Hal =
biphenSeF2 (3), biphenSeCl2 (4), biphenSeBr2 (5), and the adduct I, the stable adduct biphenSe2·I2 (7) was isolated. In addition to charac-
biphenSe·I2 (6), were isolated and identified. The extremely sensitive terization by multinuclear NMR spectroscopy, several molecular struc-
selenium(IV) difluoride 3 slowly formed significant amounts of an tures of biphen-selenium substituted halogenides were determined.
adduct with HF of the corresponding selenium(IV) oxide biphen-
In this contribution, synthetic routes to both will be re-exam-
Introduction
ined and the halogenation reactions studied.
The chemistry of covalent organotellurium(IV) halogenides
and pseudohalogenides is well established including structural
information [1–9]. The lighter homologue selenium in compa-
Results and Discussion
rable systems R2SeHal2/RSeHal3 is also examined, but less
Dibenzoselenophene (1) and Dibenzo[1,2]diselenine (2)
structural information available, also in part because of their
lower stability [10–18]. Recently, we have been able to carry
out systematic studies on organoselenium(IV) fluorides and az-
ides with alkyl and phenyl substituents [19]. In continuation of
these studies, we were interested in two materials, where sele-
nium is incorporated in a polycycle (Scheme 1), dibenzoselen-
ophene (1 ≡ biphenSe) and dibenzo[1,2]diselenine (2 ≡
biphenSe2).
The starting material for the preparation of dibenzoseleno-
phene (1 ≡ biphenSe) and dibenzo[1,2]diselenine (2 ≡
biphenSe2) is 2,2'-diiodobiphenyl, which is prepared best in
a slightly modified literature procedure according Scheme 2
[28].
Scheme 2. Preparation of 2,2'-diiodobiphenyl.
Scheme 1. Dibenzoselenophene (1) and dibenzo[1,2]diselenine (2).
In contrast to the dilithiated species 2,2'-dilithiobiphenyl
(biphenLi2) [29], diiodobiphenyl has the advantage of being
indefinitely stable at ambient temperature.
Whereas biphenSe (1) has been known for a long time [20–
26], there is much less reported about biphenSe2 (2) [25, 27].
Dibenzoselenophene (1 ≡ biphenSe) was first prepared in
1934 [20]. The most efficient route for the synthesis of 1 is
outlined in Scheme 3 [30, 31]. The lithiation with elemental
lithium is preferable compared to n-butyllithium, in order to
avoid the formation of n-butylmercury compounds. Further-
more, during our studies, we found that a temperature of
200 °C is sufficient for the formation of 1 (and not as origi-
nally described 330 °C [30]) from 2,2'-biphenyldiyl-mercury
with selenium.
* Dr. B. Krumm
Fax: +49-89-2180-77492
E-Mail: bkr@cup.uni-muenchen.de
[a] Department of Chemistry
Ludwig-Maximilian University of Munich
Butenandtstr. 5–13 (D)
81377 Munich, Germany
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/zaac.201000135 or from the
author.
View this journal online at
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1955

T. M. Klapötke, B. Krumm, M. Scherr
ARTICLE
Scheme 5. Halogenation of dibenzoselenophene (1 ≡ biphenSe).
The reactions of 1 with XeF2, SO2Cl2 and Br2 gave the ex-
pected corresponding organoselenium(IV) dihalogenides
biphenSeF2 (3), biphenSeCl2 (4), and biphenSeBr2 (5). The re-
action with iodine resulted however in the formation of a
charge transfer complex biphenSe·I2 (6), and not a sele-
nium(IV) diiodide. Table 1, shows nicely the influence of the
halogenation on the resonance of the 77Se NMR shift (left col-
umn). The strongest low field shift is observed for the sele-
nium(IV) difluoride 3, increasing the size of the halogen (or
decrease of the electronegativity) causes a high field shift ap-
proaching the resonance of the nonhalogenated starting mate-
rial 1. An indication of the weak bonding situation in the io-
dine adduct (as also proven by X-ray diffraction) gives the
only very small difference of 7 ppm in the 77Se NMR resonan-
ces of 1 and 6.
Scheme 3. Preparation of dibenzoselenophene (1 ≡ biphenSe).
The crystal structure of 1 is shown in Figure 1. Our determi-
nation at 100 K differs from the one reported in 1970 meas-
ured at 298 K [23], resulting in a different space group (P21/c,
monoclinic vs. Pbca, orthorhombic) and density (1.754 g·cm–3
vs. 1.673 g·cm–3).
Table 1. 77Se NMR resonances of 1, 2 and their halogenation products
(δ in ppm) in CDCl3.
77Se
450
77Se
biphenSe (1)
biphenSe2 (2)
347
796a) biphen(SeF3)2
1154b)
Figure 1. Molecular structure of biphenSe (1). Selected bond lengths /
Å and angles /°: Se1–C1 1.893(2), Se1–C12 1.896(2), C1–Se1–C12
86.93(10), C6–C1–Se1 112.44(17), C7–C12–Se1 112.37(16).
biphenSeF2 (3)
biphenSeCl2 (4)
biphenSeBr2 (5)
biphenSe·I2 (6)
658
581
457
biphenSe2·I2 (7)
356
a) CH2Cl2. 19F NMR: δ = –61.5 (1JF–77Se = 689 Hz); b) CH2Cl2. 19F
NMR: δ = +6.4 (br., Fax), –73.6 (br., Feq).
For the preparation of dibenzo[1,2]diselenine (2
≡
biphenSe2) it is important to lithiate 2,2'-diiodobiphenyl with
four equivalents n-butyllithium (Scheme 4), in order to achieve
a complete conversion. Due to the higher reactivity of the n-
butyl iodide, which is formed in the first step, compared to the
monolithiated iodobiphenyl towards nBuLi, in a side reaction
1-butene, butane and lithium iodide are formed. Subsequent
reaction with elemental selenium and aerial oxidation results
in the heterocycle biphenSe2 (2).
Attempts to crystallize the selenium(IV) difluoride 3 were
not successful, but did yield after storage for two weeks at
–32 °C in CH2Cl2 crystals of a different compound. These
crystals (Figure 2) were shown to be a partial hydrolysis prod-
Scheme 4. Preparation of dibenzo[1,2]diselenine (2 ≡ biphenSe2).
Halogenation of Dibenzoselenophene (1)
Figure 2. Molecular structure of biphenSeO·HF (3a). Selected bond
lengths /Å and angles /°: Se1–O1 1.694(4), Se1–C1 1.948(6), Se1–C8
1.938(5), H1–F1 0.92(4), O1···H1 1.63(6), C1–Se1–C8 85.6(2), Se1–
O1···H1 121.4(2), O1···H1–F1 138(8).
The reactivity of 1 towards bromine and iodine, respectively
halogen transfer agents xenon difluoride and sulfuryl chloride,
is illustrated in Scheme 5.
1956
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Z. Anorg. Allg. Chem. 2010, 1955–1961

Halogenation of Dibenzoselenophene and Dibenzo[1,2]diselenine
uct biphenSeO·HF (3a), which is not that surprising, consider- radii of selenium and chlorine (vdWr SeCl 3.65 Å) [34]. These
ing the extreme sensitivity of selenium(IV) fluorides towards intermolecular interactions (Se1···Cl1 3.378(2) and Se1···Cl2
traces of moisture.
3.346(2) Å) are significantly shorter than in Me2SeCl2 (3.41–
The selenium atom is pseudo-tetrahedrally coordinated with a 3.61 Å) [17] and connect the single molecules to chains along
Se1–O1 bond length of 1.694(4) Å, which is slightly longer than the c axis (Figure 4, left). Taking these interactions into ac-
the mesityl-substituted derivative Mes2SeO·HF (1.674(4) Å) count, the coordination of the selenium atom is distorted octa-
[19]. Both Se–C bond lengths (Se1–C1 1.948(6), Se1–C8 hedral. Interestingly, in the structures of the phenyl and chlo-
1.938(5) Å) are comparable with the latter (1.941(4), roethyl derivatives Ph2SeCl2 and (ClC2H4)2SeCl2 there were
1.953(5) Å). Due to the 2,2'-biphenyldiyl substituent the C1– no such intermolecular contacts reported. Probably because of
Se1–C8 angle (85.6(2)°) differs significantly from the mesityl the enforced steric conformation of the 2,2'-biphenyldiyl sub-
derivative (100.7(2)°), but is still in the same range of the start- stituent, these contacts in 4 were enabled. Especially the very
ing material 1 (86.93(10)°). The oxygen atom is part of a hydro- small C–Se–C angle and the planar configuration of the biphen
gen bridge interaction with a donor–acceptor distance of substituent, allow more space in the vicinity of the selenium
2.391(5) Å (O1···H1 1.63(6) Å) and an Se1–O1···H1 angle of atom to create interactions with adjacent molecules.
121.4(2)°.
The crystal structures of the selenium(IV) dichloride 4 and
also dibromide 5 are shown in Figure 3 left and right. Two
molecules of the dibromide were found in the asymmetric unit,
but since there are only marginal differences, only one is dis-
played with selected bond parameters.
Figure 4. Intermolecular contacts in biphenSeCl2 (4, left) and
biphenSeBr2 (5, right), hydrogen atoms not shown. Selected distances /
Å: Se···Cl 3.346(2)/3.378(2), Se···Br 3.434(3)/3.491(3).
The Se–Br bond in 5 (2.5788(14) Å) is only slightly longer
Figure 3. Molecular structure of biphenSeCl2 (4, left) and biphenSeBr2
than the corresponding methyl analogue Me2SeBr2
(2.546(4) Å) [17]. As already discussed for 4, in the crystal
structure of the selenium(IV) dibromide there are as well sec-
ondary interactions present below the sum of the van der Waals
radii of selenium and bromine (vdWr SeBr 3.75 Å) [34] (Fig-
ure 4, right). Those intermolecular contacts between the two
(5, right), hydrogen atoms not shown. Selected bond lengths /Å and
angles /°: biphenSeCl2: Se1–C1 1.912(6), Se1–C8 1.929(6), Se1–Cl1
2.368(2), Se1–Cl2 2.430(2), C1–Se1–C8 87.2(3), Cl1–Se1–Cl2
178.41(6); biphenSeBr2: Se1–C1 1.933(3), Se1–Br1 2.5788(14), C1–
Se1–C1(i) 86.82(19), Br1–Se1–Br1(i) 179.08(2); with i = –x, y, 1½–z.
The selenium–carbon bond lengths (4: Se1–C1 1.912(6), independent molecules (Se1···Br2 3.491(3) und Se2···Br1
Se1–C8 1.929(6) Å; 5: Se1–C1 1.933(3) Å) and angles (4: 3.434(3) Å) are, as to be expected because of the larger bro-
C1–Se1–C8 87.2(3)°; 5: C1–Se1–C1(i) 86.82(19)°) are similar mine atom compared to chlorine, slightly longer as in the sele-
in both halogenides and comparable with those found in bi- nium(IV) dichloride 4 and lead also to chain-type packing and
phenSe (1) and biphenSeO·HF (3a). The halogen–selenium– a distorted octahedral coordination around the selenium atom.
halogen angles are in both compounds almost linear (4:
In contrast to the selenium(IV) dichloride 4 and dibromide
178.41(6)°; 5: 179.08(2)°) and lead to the expected pseudo- 5, the reaction with iodine leads to the formation of a charge
trigonal-bipyramidal arrangement around the selenium atom transfer adduct biphenSe·I2 (6) (Figure 5), as outlined in
with both halogen atoms in the axial positions and free lone- Scheme 5.
pair of selenium in the equatorial plane.
Both Se–C bond lengths of 6 (Se1–C1 1.910(5) and Se1–C8
Whereas the shorter Se–Cl bond in 4 (Se1–Cl1 2.368(2) Å) 1.913(5) Å) and the C–Se–C angle (86.6(2)°) are comparable
is in the range of those found in the structures of the organose- with those parameters of the structures of 3a, 4 and 5. The
lenium(IV) dichlorides Ph2SeCl2, (ClC2H4)2SeCl2 und Se1···I1 distance (3.001(6) Å) is significantly longer than those
Me2SeCl2 (2.31–2.41 Å) [17, 18, 32, 33], the other Se–Cl bond found in the charge transfer adducts of Me2Se·I2 (2.768(4) Å)
(Se1–Cl2 2.430(2) Å) is slightly elongated and beyond that [17],
(CH2)4Se·I2
(2.762(5) Å)
[35],
O(CH2)4Se·I2
range. Similar as in the structure of the methyl derivative (2.755(4) Å) [36], (CH2Se)3·I2 (2.734(1) Å) [37] and
Me2SeCl2, in the structure of 4 there are secondary Se···Cl in- C4H7NSSe·I2 (2.726(1) Å) [38]. This relatively weak donor
teractions, which are shorter than the sum of van der Waals ability of the biphenSe unit in 6 does not significantly weaken
Z. Anorg. Allg. Chem. 2010, 1955–1961
© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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1957

T. M. Klapötke, B. Krumm, M. Scherr
ARTICLE
broadened resonances for the inequivalent axial (δ = +6.4) and
equatorial (δ = –73.6) fluorine atoms are observed (Table 1,
right column).
The corresponding bis-selenium(IV) trihalogenides from the
reactions with SO2Cl2 and Br2 could not be detected and de-
composed immediately, according to 77Se NMR spectroscopy,
to the corresponding monoselane biphenSe (1). Another de-
composition product from the reaction with SO2Cl2 according
to the 77Se NMR spectrum is Se2Cl2 (δ = 1283 in CH2Cl2;
1282 in D2O [41]). From an intermediate formation of a bis-
selenium(II) halide species, biphen(SeCl)2, SeCl2 could be
eliminated with formation of 1. Three equivalents of SeCl2 are
in equilibrium with Se2Cl2 and SeCl4 (Scheme 6) [42]; the lat-
ter was identified by Raman spectroscopy. Probably similar
pathways have occurred with the attempted bromination reac-
tion; however, no such spectroscopic or experimental evidence
was found.
The reaction of 2 with iodine furnished, as already found
with the analogous reaction with 1, a charge transfer adduct,
biphenSe2·I2 (7), which was identified by means of X-ray crys-
tallography. In addition, the small low field shift difference of
the 77Se NMR resonance of 7 (356 ppm) vs. that of biphenSe2
(2) (347 ppm) already indicates, that a similar adduct forma-
tion, as observed for the reaction of biphenSe (1) with iodine,
must have occurred (Table 1). It is noteworthy, that there is
only one 77Se NMR resonance found for both selenium atoms
in 7, which means in solution the iodine is equally bonded to
both selenium atoms. However, in the crystalline state, the io-
dine unit is located near Se2 (Figure 6).
Figure 5. Molecular structure of biphenSe·I2 (6), hydrogen atoms not
shown. Selected bond lengths /Å and angles /°: Se1–C1 1.910(5), Se1–
C8 1.913(5) Se1···I1 3.001(6), I1–I2 2.7889(6), C1–Se1–C8 86.6(2),
Se1···I1–I2 174.01(2).
the I1–I2 bond (2.7889(6) Å). Therefore, this I–I bond is sig-
nificantly shorter than those in the structures of Me2Se·I2
(2.916(3) Å) [17], (CH2)4Se·I2 (2.914(4) Å) [35], O(CH2)4Se·
I2 (2.956(3) Å) [36], (CH2Se)3·I2 (2.944(1) Å) [37] and
C4H7NSSe·I2 (2.983(1) Å) [38], and is also very close to the
iodine–iodine bond in solid iodine (2.715(6) Å) [39]. Apart
from this Se···I contact there are no further interactions below
the sum of the van der Waals radii of both elements (vdWr SeI
3.88 Å) [34], resulting in a layered structure along the b axis.
In contrast, the reaction of iodine with the Te analogue telluro-
phene leads to the formation of the organotellurium(IV) diiod-
ide biphenTeI2, which crystal structure is displaying the same
octahedral coordination of the central tellurium atom as 4 and
5 with two secondary interactions [40].
Halogenation of Dibenzo[1,2]diselenine (2)
The reactivity of 2 towards bromine and iodine, respectively
halogen transfer agents xenon difluoride and sulfuryl chloride,
is illustrated in Scheme 6.
Figure 6. Molecular structure of biphenSe2·I2 (7), only one of the two
independent molecules shown, hydrogen atoms not shown. Selected
bond lengths /Å and angles /°: Se1–Se2 2.3415(8), Se1–C1 1.917(5),
Se2–C8 1.920(5), Se2···I1 2.9095(6), I1–I2 2.8412(5), C1–Se1–Se2
93.27(15), C8–Se2–Se1 93.76(15), Se2···I1–I2 175.71(2).
Scheme 6. Halogenation of dibenzo[1,2]diselenine (2 ≡ biphenSe2).
The reactions of biphenSe2 (2) with stoichiometric amounts
(3 equivalents) of the halogens, respectively halogen equiva-
lents (Scheme 6), furnished only with XeF2 detectable
The asymmetric unit of 7 consists of two independent mole-
amounts of the unstable bis-selenium(IV) trifluoride cules, which differ only in their Se···I and I–I distances. Com-
biphen(SeF3)2. The 77Se NMR spectrum of the reaction mix- pared to 6, the selenium atom is in one of the two molecules
ture shows after 30 min the main resonance at δ = 1154 and a better donor in the charge transfer adduct (Se2–I1 2.9095(6),
already a further resonance at δ = 1072, which indicates start- I1–I2 2.8412(5) Å), in the other one a slightly weaker donor
ing decomposition. In the 19F NMR spectrum the expected two (Se3–I3 3.227(3), I3–I4 2.7520(5) Å). In the latter case the
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Halogenation of Dibenzoselenophene and Dibenzo[1,2]diselenine
iodine–iodine bond is only marginally longer than found for was observed. Thorough structural studies by X-ray crystallog-
solid iodine (2.715(6) Å) [39]. The Se–Se bonds are almost raphy, where possible, were carried out.
identical (Se1–Se2 2.3415(8), Se3–Se4 2.3434(8) Å), and only
marginally longer than those in the crystal structure of
biphenSe2 (2.32–3.23 Å) [43]. In the crystal structure of the
Experimental Section
adducts [Ph2Se2·I2]2 [44], and [tipp2Se2]2·I2 (tipp = 2,4,6-triiso-
propylphenyl) [45], the only other determined structures for
such iodine adducts of diselanes, similar distances for Se–Se
and I–I bonds are found (2.347/2.353 and 2.775/2.772 Å). Re-
garding the Se···I–I angles, both angles (Se2···I1–I2
175.71(2)°, Se3···I3–I4 174.75(2)°) are similar to that of 6
(174.01(2)°). Both six-membered rings of the 2,2'-biphenyldiyl
General Procedures
All manipulation of air- and moisture-sensitive materials were per-
formed in an inert atmosphere of dry argon using flame-dried glass
vessels or oven-dried plastic equipment and Schlenk techniques [46].
The solvents were dried by standard methods, and freshly distilled
prior to use. Diiodobiphenyl was prepared according to the literature
procedure; n-butyllithium (2.5 m in hexanes), xenon difluoride
unit are twisted, in contrast to the structures of the dihaloge- (ABCR), bromine and iodine were used as received, sulfuryl chloride
was distilled prior to use. Infrared spectra were recorded with Perkin–
Elmer Spektrum One FT–IR or Nicolet 520 FT–IR spectrometers (as
neat liquids/solids or Nujol mulls), Raman spectra with a Perkin–Elmer
2000 NIR FT spectrometer fitted with a Nd-YAG laser (1064 nm) as
neat solids or liquids. NMR spectra were recorded with a JEOL Eclipse
400 instrument, and chemical shifts were determined with respect to
external Me4Si (1H, 399.8 MHz; 13C, 100.5 MHz), CFCl3 (19F,
376.1 MHz), and Me2Se (77Se, 76.3 MHz). Due to the temperature
dependence of the 77Se NMR resonances, all samples were recorded
at 25 °C. Elemental analyses were not performed, because of the small
nides of the monoselane 4 and 5, due to the diselane bridge,
in a range of 41.4(7)° resp. 41.7(7)°.
Besides both shortest Se···I contacts in the asymmetric unit,
there are several other secondary interactions present, which
are shorter than the sum of the van der Waals radii (vdWr SeI
3.88 Å [34]) (Figure 7). Except the selenium atom Se1, where
there is only one contact, the other three selenium atoms have
each two contacts to adjacent iodine atoms, which are in the
range of 2.91–3.80 Å. These contacts lead to a complex three-
dimensional network, in sharp contrast to the isolated molecu- amounts of the compounds and in part high sensitivity towards mois-
ture and/or temperature.
les in the structure of 6.
X-ray Crystallography
For all compounds an Oxford Xcalibur3 diffractometer with a CCD
area detector was employed for data collection using Mo-Kα radiation
(λ = 0.71073 Å). The structures (Table 2) were solved by direct meth-
ods (SHELXS [47] or SIR97 [48]) and refined by full-matrix least-
squares on F2 (SHELXL [47]). All non-hydrogen atoms were refined
anisotropically. The HF hydrogen atoms were located in a difference
Fourier map and placed with a H–F distance of 0.92 Å. ORTEP plots
are shown with thermal ellipsoids at the 50 % probability level. Crys-
tals were obtained by slow evaporation of CH2Cl2 solutions at ambient
temperature or at low temperature (3a). CCDC-693670, -693671,
-693672, -693673, -693674, -693675 contain the supplementary crys-
tallographic data for this paper. These data can be obtained free of
charge via www.ccdc.cam.ac.uk/data_request/cif, or by emailing data_
request@ccdc.cam.ac.uk, or by contacting The Cambridge Crystallo-
graphic Data Centre, 12, Union Road, Cambridge CB2 1EZ, UK; Fax:
+44-1223-336033.
Preparation of Dibenzoselenophene (1) and Dibenzo[1,2]di-
selenine (2)
Figure 7. Intermolecular interactions in biphenSe2·I2 (7), hydrogen at-
oms not shown. Selected distances /Å: Se1···I2(i) 3.801(9), Se2···I1
2.9095(6), Se2···I1(ii) 3.757(10), Se3···I2(ii) 3.694(9), Se3···I3
3.227(3), Se4···I4(iii) 3.435(5), Se4···I3(iv) 3.756(13); with i = 1+x, y,
z, ii = –x, –y, –z, iii = –1+x, y, z, iv = –x,–y,–1–z.
(1): Into a pale yellow solution of diiodobiphenyl (6.16 mmol) in ethyl
ether (30 mL) were added lithium granules (37.0 mmol), and the mix-
ture was heated to reflux for four hours. After separation of the excess
lithium, the remaining brown solution was added dropwise to a solu-
tion of mercury(II) chloride (5.54 mmol) in ethyl ether (40 mL) at
ambient temperature. The resulting colorless precipitate of 2,2'-biphen-
yldiylmercury was filtered and washed with ethyl ether and dried in
vacuo (yield: 2.1 g biphenHg). BiphenHg (1.98 mmol) was mixed
thoroughly with selenium (6.61 mmol) in a mortar and this mixture
was heated in a sublimation vessel in several portions. The resulting
product dibenzoselenophene (biphenSe, 1) was sublimed at 200 °C/
10–3 mbar slowly over a period of nine hours as a colorless solid (59 %
Conclusions
The syntheses of the selenium heterocycles dibenzoseleno-
phene and dibenzo[1,2]diselenine were optimized and haloge-
nation studies were performed. Whereas with fluorine, chlorine
and bromine the expected oxidation into selenium(IV) oc-
curred, with iodine the formation of charge transfer adducts yield, calculated with respect to biphenI2).
Z. Anorg. Allg. Chem. 2010, 1955–1961
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1959

T. M. Klapötke, B. Krumm, M. Scherr
ARTICLE
Table 2. Crystal and structure refinement data.
biphenSe (1)
biphenSeO·HF (3a)biphenSeCl2 (4)
biphenSeBr2 (5) biphenSe·I2 (6)
biphenSe2·I2 (7)
Empirical formula
C12H8Se
C12H9FOSe
267.16
100
C12H8Cl2Se
302.06
100
C12H8Br2Se
390.96
100
C12H8I2Se
484.96
200
C24H16I4Se4
1127.81
200
Formula mass /g·mol–1 231.15
Temperature /K
Crystal size /mm
Crystal description
Crystal system
Space group
a /Å
100
0.39 × 0.09 × 0.08 0.07 × 0.06 × 0.05 0.11 × 0.11 × 0.05 0.18 × 0.16 × 0.09 0.19 × 0.13 × 0.13 0.25 × 0.14 × 0.07
colorless needle
monoclinic
P21/c
colorless block
monoclinic
P21/c
yellow platelet
orthorhombic
Pccn
18.032(5)
18.911(5)
7.608(5)
orange block
monoclinic
P2/c
red block
triclinic
violet platelet
triclinic
¯
¯
P1
P1
4.61223(11)
15.3295(4)
12.3973(3)
92.784(2)
875.49(4)
4
4.9914(9)
12.371(3)
16.2633(15)
92.716(13)
1003.1(3)
4
7.628(5)
5.0225(3)
10.9820(7)
12.1547(9)
101.619(6)
640.79(8)
2
9.7271(5)
10.1422(5)
15.2257(9)
103.495(5)
1418.46(13)
2
b /Å
10.063(5)
15.954(5)
103.231(5)
1192.1(10)
4
c /Å
β /°
V /Å3
2594(2)
Z
8
ρcalc /g·cm–3
1.754
1.769
1.547
2.178
2.514
2.641
μ /mm–1
4.228
3.724
3.271
9.815
7.713
9.538
F(000)
456
528
1184
736
440
1016
θ range /°
Index ranges
4.2–26.0
–5 ≤ h ≤ 5
–18 ≤ k ≤ 18
–15 ≤ l ≤ 15
6521
4.1–26.0
–6 ≤ h ≤ 5
–15 ≤ k ≤ 11
–20 ≤ l ≤ 20
5873
0.9–26.0
–22 ≤ h ≤ 22
–23 ≤ k ≤ 23
–9 ≤ l ≤ 9
22677
1.0–26.0
–9 ≤ h ≤ 8
–12 ≤ k ≤ 12
–19 ≤ l ≤ 19
12411
1.0–28.8
–6 ≤ h ≤ 6
–13 ≤ k ≤ 13
–16 ≤ l ≤ 16
6249
3.7–26.0
–11 ≤ h ≤ 11
–12 ≤ k ≤ 12
–18 ≤ l ≤ 18
15872
Reflections collected
Reflections observed
Reflections unique
1393
1721
(Rint = 0.0289)
0.0215, 0.0469
0.0327, 0.0510
1253
1963
(Rint = 0.1061)
0.0502, 0.1062
0.0781, 0.1207
0.831/0.769
1963/1/140
1197
2399
(Rint = 0.0721)
0.0558, 0.1024
0.0790, 0.1126
0.850/0.709
2399/0/136
1554
2349
(Rint = 0.0250)
0.0203, 0.0456
0.0420, 0.0544
0.410/0.189
2349/0/137
1713
3345
(Rint = 0.0317)
0.0318, 0.0692
0.0594, 0.0739
0.370/0.247
3345/0/136
3331
5552
(Rint = 0.0385)
0.0256, 0.0370
0.0547, 0.0417
0.513/0.214
5552/0/289
R1, wR2 (2σ data)
R1, wR2 (all data)
Max./ min. transmission 0.710/0.310
Data/restraints/
parameters
1721/0/118
1.06
GOOF on F2
Larg. diff. peak
/hole /e·Å–3
0.95
0.89
1.02
0.91
0.84
0.47/–0.42
1.01/–0.99
0.52/–0.53
0.50/–0.42
0.99/–0.88
0.65/–0.64
6: α = 95.123(6)°, γ = 100.226(6)°; 7: α = 97.059(4)°, γ = 99.791(4)°
1H NMR (CDCl3): δ = 7.68 (m), 7.57 (m), 7.38 (m), 7.15 (m); 13C{1H} Difluoro-2,2'-biphenyldiyl-λ4-selane, biphenSeF2 (3): The product 3,
NMR (CDCl3): δ = 139.3 (1JC–77Se = 100.3 Hz), 138.2, 126.8 a pale-yellowish solid, decomposed within 24 hrs at 25 °C, resulting
(3JC–77Se = 7.7 Hz), 126.0 (2JC–77Se = 17.3 Hz), 124.8, 122.8. 77Se in unidentifiable materials. 19F NMR (CH2Cl2): δ = –61.5 (1JF–77Se
=
NMR (CDCl3): δ = 450.
689 Hz). 77Se NMR (CH2Cl2): δ = 796 (br).
Dichloro-2,2'-biphenyldiyl-λ4-selane, biphenSeCl2 (4): Yellow solid.
1H NMR (CDCl3): δ = 7.85 (m), 7.68 (m), 7.41 (m), 7.28 (m); 13C{1H}
NMR (CDCl3): δ = 145.1 (1JC–77Se = 131.4 Hz), 141.8, 135.9, 129.0,
128.1, 124.2. 77Se NMR (CDCl3): δ = 658.
(2): Into a solution of biphenI2 (2.71 mmol) in THF (30 mL) n-butyl-
lithium (10.84 mmol) was slowly added at –65 °C. The solution turned
initially from pale yellow to intense yellow and to milky colorless
upon complete addition of nBuLi. After 4 hours stirring at –65 °C,
elemental selenium (5.96 mmol) was added and the mixture was al-
lowed to warm up to ambient temperature to give a clear yellow solu-
tion. This solution was added dropwise to a solution of NH4Cl (30 %,
100 mL) and thoroughly stirred under contact with air for two hours.
After addition of ethyl ether (60 mL), the red-orange organic layer was
separated, washed with water, and the solvents were removed in vacuo.
The resulting red oil was further dried in high vacuum to give a red
crystalline solid (89 % yield).
Dibromo-2,2'-biphenyldiyl-λ4-selane, biphenSeBr2 (5): Orange
1
solid. H NMR (CDCl3): δ = 7.87 (m), 7.52 (m), 7.33 (m), 7.08 (m);
13C{1H} NMR (CDCl3): δ = 145.2 (1JC–77Se = 119.8 Hz), 136.4, 127.9,
120.8, 118.1, 115.4. 77Se NMR (CDCl3): δ = 581.
Dibenzoselenophene-iodine (6): Red solid, identified via X-ray dif-
fraction as the adduct biphenSe·I2 (6). 1H NMR (CDCl3): δ = 7.60
(m), 7.50 (m), 7.35 (m), 7.18 (m); 13C{1H} NMR (CDCl3): δ = 139.2
(1JC–77Se = 112.9 Hz), 137.9, 126.9, 126.1, 124.8, 122.6. 77Se NMR
(CDCl3): δ = 457.
1H NMR (CDCl3): δ = 7.71 (m), 7.61 (m), 7.34 (m), 7.21 (m); 13C{1H}
NMR (CDCl3): δ = 141.9 (1JC–77Se = 151.3 Hz), 131.8 (2JC–77Se
18.8 Hz), 131.1, 129.6, 128.8, 127.5. 77Se NMR (CDCl3): δ = 347.
=
Halogenation of dibenzoselenophene (1): Into solutions of 1 (0.5–
Halogenation of Dibenzo[1,2]diselenine (2)
1.0 mmol) in dichloromethane (5–10 mL) was added XeF2, or SO2Cl2,
or Br2, or I2 (0.55–1.1 mmol) at 0 °C (iodine at 25 °C), and the mix- 2,2'-Bis(trifluoro-λ4-selanyl)biphenyl, biphen(SeF3)2: Into a solution
tures were stirred for 30 min at this temperature. After stirring a further of freshly dried 2 (0.3 mmol) in dichloromethane (2 mL) XeF2 was
hour at ambient temperature, all volatile materials were removed in added (0.75 mmol) at 0 °C. An immediate color change from red to
vacuo, which resulted in the solid materials in yields of 60–80 %.
pale yellow was observed. After stirring for 30 min at 0 °C, an NMR
1960 www.zaac.wiley-vch.de
© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Z. Anorg. Allg. Chem. 2010, 1955–1961

Halogenation of Dibenzoselenophene and Dibenzo[1,2]diselenine
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trifluoride biphen(SeF3)2.
19F NMR (CH2Cl2): δ = 6.4 (br., Fax: ), –73.6 (br., Feq). 77Se NMR
(CH2Cl2): δ = 1154 (br). Further unidentified resonance after few hours
at 25 °C: 77Se NMR (CH2Cl2): δ = 1072.
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Reaction of biphenSe2 (2) with SO2Cl2: Into a solution of 2
(0.4 mmol) in dichloromethane (5 mL) sulfuryl chloride (1.45 mmol)
was added dropwise at 0 °C and the mixture was stirred 30 min at this
temperature. The yellowish mixture was concentrated to 1 mL volume
in vacuo and examined by NMR spectroscopy. Identified were 1,
Se2Cl2, 4 (all by 77Se NMR resonance) and SeCl4 (Raman).
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dichloromethane (10 mL) bromine (14.5 mmol) was added dropwise
at 0 °C. After approximately 30 min an orange colored solid precipi-
tated, which was separated and washed with CCl4, and identified by
77Se NMR spectroscopy as 5. In the reaction solution 1 was detected
by 77Se NMR spectroscopy.
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NMR (CDCl3): δ = 141.9 (1JC–77Se = 148.1 Hz), 132.0, 131.3, 129.3,
127.5, 126.9. 77Se NMR (CDCl3): δ = 341.
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Supporting Information (see footnote on the first page of this article):
X-ray crystallographic files (CIF) of crystal data collection and refine-
ment parameters, atomic coordinates, bond lengths and angles, aniso-
tropic displacement parameters for compounds 1, 3a, 4, 5, 6 and 7.
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Acknowledgement
Financial support of this work by the University of Munich, the Fonds
der Chemischen Industrie and the Deutsche Forschungsgemeinschaft
(KL 636/10–1) is gratefully acknowledged. We wish to thank the re-
search student Ms. S. Prell for her strong engagement during the prepa-
ration of some compounds presented in this study.
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Received: March 18, 2010
Published Online: June 22, 2010
Z. Anorg. Allg. Chem. 2010, 1955–1961
© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.zaac.wiley-vch.de
1961