A77Se NMR study of elemental selenium reduction using NaBH4

Article abstract of DOI:10.1016/j.jorganchem.2016.01.028

Alkylation or arylation of selenide or diselenide anions is a well-established method to obtain organoselenium compounds. Nevertheless, detecting inorganic selenium anions using⁷⁷Se NMR is still a challenge. In a previous work, alkylation of Na₂Se was found sometimes to yield a mixture of organyl selenides/diselenides in variable amounts. In the literature, this mixture is sometimes attributed to the oxidation of an intermediate alkyl selenol during the extraction. To understand this process, a series of experiments using⁷⁷Se NMR were performed. It was clear from the⁷⁷Se NMR experiments that NaHSe^-and Se22- formation was very dependent on the NaBH₄stoichiometry used. After alkylation, alkyl selenol and dialkyl diselenide were identified, proving they were not formed during the extraction step. As a result, alkyl selenols, dialkyl selenides or dialkyl diselenides with a high purity degree were obtained. To achieve high purity and selectivity of the organoselenium compound, the stoichiometric ratio between Se⁰/NaBH₄has to be carefully measured.

Full text of DOI:10.1016/j.jorganchem.2016.01.028

Accepted Manuscript
77
A
Se NMR study of elemental selenium reduction using NaBH
4
Alfredo Ricardo Marques de Oliveira, Leandro Piovan, Fabio Simonelli, Anderson
Barison, Maria de Fatima C. Santos, Murilo Belini Marcondes de Mello
PII:
S0022-328X(16)30029-8
10.1016/j.jorganchem.2016.01.028
JOM 19379
DOI:
Reference:
To appear in: Journal of Organometallic Chemistry
Received Date: 22 November 2015
Revised Date: 20 January 2016
Accepted Date: 21 January 2016
Please cite this article as: A.R.M. de Oliveira, L. Piovan, F. Simonelli, A. Barison, M. de Fatima C.
77
Santos, M.B.M. de Mello, A Se NMR study of elemental selenium reduction using NaBH , Journal of
4
Organometallic Chemistry (2016), doi: 10.1016/j.jorganchem.2016.01.028.
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ACCEPTED MANUSCRIPT

ACCEPTED MANUSCRIPT
1
7
7
A Se NMR study of elemental selenium reduction using
NaBH4
Murilo B. M. de Mello, Maria de Fátima C. Santos, Fabio Simonelli, Leandro Piovan,
*
Andersson Barison, Alfredo R. M. Oliveira
Abstract: Alkylation or arylation of selenide or diselenide anions is a well- Organoselenium compounds can be obtained mainly through two
established method to obtain organoselenium compounds. Nevertheless, synthetic strategies starting from elemental selenium: a) reaction with
7
7
detecting inorganic selenium anions using Se NMR is still a challenge. In a convenient organometallic compound (RLi, RMgBr, etc.) to generate
-
+
0
a previous work, alkylation of Na
mixture of organyl selenides/diselenides in variable amounts. In the selenide or diselenide anion (Se or Se
literature, this mixture is sometimes attributed to the oxidation of an (Scheme 1). To accomplish reduction, several agents, such as alkaline
2
Se was found sometimes to yield a an organyl selenolate anion (RSe M ); or b) reduction of Se to
2
-
2-
2
), followed by alkylation
8
9
10
11
intermediate alkyl selenol during the extraction. To understand this metals in liquid ammonia , Li(Et)
3
BH, SmI
2
,
NaH in DMF, or
77
12
process, a series of experiments using Se NMR were performed. It was Rongalite , can be used.
7
7
-
2-
clear from the Se NMR experiments that NaHSe and Se
2
formation was
very dependent on the NaBH stoichiometry used. After alkylation, alkyl
4
selenol and dialkyl diselenide were identified, proving they were not formed
during the extraction step. As a result, alkyl selenols, dialkyl selenides or
dialkyl diselenides with a high purity degree were obtained. To achieve high
purity and selectivity of the organoselenium compound, the stoichiometric
0
ratio between Se /NaBH
4
has to be carefully measured.
7
7
Keywords: NaHSe SeNMR detection, selenium reduction, selenide
trapping.
Scheme 1. Methods to selectively synthesize selenium compounds.
2
-
It is well known that the reaction of inorganic selenium anion (Se or
1
. Introduction
2-
Se
selenols (RSeH), diorganyl selenides (RSeR) or diorganyl diselenides
RSeSeR). Moreover, selectivity depends on the stoichiometry ratio
2
) with an organic electrophile (RX) allows the synthesis of organyl
Over the last 50 years or so, the status of organoselenium compounds
has changed from being considered highly toxic to a point where some
of its members can be bought as food supplements, at local markets or
pharmacies. Selenium is an essential trace element and lower levels of
it in humans has been associated to several diseases including cancer
and heart diseases.
deficiency was the Keshan disease, which was identified some 50
years ago in northeast part of continental China and recently
(
13
used at the reduction step. Since the use of liquid ammonia imposes
a series of experimental restrictions, the reduction reaction of selenium
4
with NaBH (1) in ethanol is a convenient method to prepare selenide
anion. In addition, to simplify the experimental procedure, Yang
1
,4a
One illustrative disease related to selenium
reported that the presence of NaOH in this reaction eliminates
14
2 2
hydrogen generation, when synthesizing sodium diselenide (Na Se ).
Recently we had reported that during the synthesis of bis-2-methylene-
-oxazolinyl selenide (which involved the use of Na Se from the
(1) in ethanol), a mixture of
2
reviewed. Selenium ingestion is almost exclusively via food and it´s
bioavailability contents in it depends of the selenium level in soil.
2
2
3
0
reduction of Se (2) using NaBH
4
Selenium plays an important role as participant of several antioxidant
enzymes such as glutathione peroxidase (GPx), thioredoxin reductase
dioxazolinyl selenides and dioxazolinyl diselenides has sometimes
been observed, even when oxygen and water was carefully avoided.
15
4
a-c
(TrxR) and iodothyronine deiodinases (IDD).
Selenocistein,
The available literature about this reduction reports conflicting results,
recognized as the 21th amino acid essential for life, is found in several
0
where different stoichiometric ratios of reducing agent to Se have
5
,6
proteins. In mamals at least 30 selenoproteins were identified, and
been used to generate the same species or even worse, mixed
7
there is an estimative that humans have about 25 selenoproteins.
2-
2- 16
species in different ratios (Se + Se
2
). This apparent contradiction
7
7
prompted us to make a deeper Se NMR study to investigate which
selenium species were generated under selected conditions. Se has a
spin nucleus, no quadrupolar moment and isotopic abundance
7
7
[a]
½
Alfredo Ricardo Marques de Oliveira, Leandro Piovan, Fabio Simonelli,
Anderson Barison, Maria de FatimaC. Santos and Murilo Belini
Marcondes de Mello
Universidade Federal do Paraná, Departamento de Química
Centro Politécnico, Curitiba, Brasil 81.531-980
around 8%. These properties allows to acquire high resolution NMR
spectra with sharp and high intensity signals over a wide chemical shift
77
range. Se NMR spectroscopy can be used as a tool to follow reaction
1
13
progress in an easy and direct way than those by H and C, where
7
7
e-mail:armo@quimica.ufpr.br, lpiovan@quimica.ufpr.br, murilo@ufpr.br
http://www.quimica.ufpr.br
spectra are far more complex. Se NMR spectroscopy was previously
1
7
2-
18
used by McFarlane to investigate the Se
x
(x>2) anion. Eggert and
.
19
Björgvinsson used the same tool to investigate the formation and

ACCEPTED MANUSCRIPT
2
stability of polyselenides. However, the results were disappointing, indicated greater amounts of 7 and/or 8 in solution, as confirmed by
2
-
20
77
since none of the authors could identify Se
2
species. Similarly, in
Se NMR analysis.
2
1
-
1
991 Cusik and Dance reported the characterization of [HSe] and It is known that NaBH
4
(1) slowly decomposes in the presence of
2
-
77
2-
24
0
[
Se
x
]
ions using Se NMR but were unable to identify the [Se
2
]
ion. ethanol. Thus, to study its influence on the reduction of Se (2), one
(1) was carefully weighed and dissolved in 1 mL of
HSe] in DMF is large, around 1 ppm per degree. Having this in mind, anhydrous ethanol. It was immediately possible to detect a small
we decided to trap any selenium species formed in the reduction amount of gas being slowly released. Upon addition of this solution to
Low temperature studies from the same group, shows that δSe for equiv. of NaBH
4
-
[
7
7
0
reaction using an alkylating agent and following the results with Se a flask containing solid Se (2), a copious amount of hydrogen was
NMR analysis. released. This indicates that most NaBH (1) was active, but the final
solution had a reddish-brown color. Titrating the resulting solution with
a small volume of diluted NaBH (1) ethanol solution yielded a
colorless limpid solution. As expected, further addition of BnCl (9)
4
2
2
. Results
.1 Synthesis and Se NMR study of NaHSe (3) species.
4
7
7
2
2
77
We began our work by using Se NMR to investigate the nature of yielded only benzyl selenol (6). This result indicates that generation of
0
the selenium species generated from the reaction of Se with different pure NaHSe (3) is very sensitive to the amount/quality of NaBH
stoichiometric ratios of NaBH (1) in ethanol, into NMR tubes. For all used and any deviation can result in formation of varying amounts of
NMR assays, diphenyl diselenide (14) (463 ppm) was employed as alkyl selenol (from NaHSe (3)), dialkyl selenide (from double alkylation
4
(1)
4
0
external reference. Thus, one equiv. of Se (2) (19.7 mg, 0.25 mmol) of NaHSe (3)) and dialkyl diselenides (from Na
2 2
Se (5)) (Figure 2).
and one equiv. of NaBH (1) (9.4 mg. 0.25 mmol) (eq. 1) were placed
4
into a 5 mm NMR tube followed by careful addition of 1 mL of
anhydrous ethanol. The tube was capped with a small rubber septum
with an outlet needle and degassed using purified nitrogen gas. This
7
7
solution was limpid and light reddish-brown colored. The
Se
hydrogen decoupled NMR spectrum for this solution showed only one
signal at -496 ppm. When a coupled spectrum was acquired, this
signal split into a doublet with a coupling constant of 23 Hz (Figure 1)
PhSeSePh
1
4
(14)
that was assigned to NaHSe (3). Cusik reported a similar result in
water, with a chemical shift of -519 ppm and a coupling constant of 26
Hz.
5
00
450
400
1
350
300
250
200
150
100
50
ppm
7
7
Figure 2. Se { H} NMR spectrum showing the signals for benzyl
selenol (6) (83.6 ppm), dibenzyl selenide (7) (330.9 ppm), dibenzyl
diselenide 8 (401.1 ppm) and diphenyl diselenide(14) (463 ppm).
A
B
2
This reaction was repeated in an attempt to identify Na Se (4) and the
NMR spectrum was swept for a wide spectral width, to look for the
presence of any other selenium species. The only observed signal was
the singlet at -496 ppm. Its coupled spectrum showed a doublet
-486
-487
-488
-489
-490
-491
-492
-493
-494
-495
-496
-497
ppm
(
J=23Hz) assigned to NaHSe. Upon treatment with a 5% NaOH
aqueous solution, the coupled spectra changed to a deformed singlet
at -491 ppm. This signal is not compatible with a Na Se (4) species
since it has the same chemical shift of NaHSe (3). The observed line
C
2
2
5
600
500
400
300
200
100
0
-100
-200
-300
-400
-500
ppm
7
7
77
1
2-
- 21
Figure 1. (A) NaHSe Se NMR spectrum. Expanded Se { H} NMR broadening can be attributed to a fast exchange of Se with HSe .
7
7
1
(
B). (C) Se { H} NMR full spectrum of NaHSe (3) in ethanol solution.
Once more, the NMR field was swept for a wide spectral width and no
When one equivalent of benzyl chloride ( BnCl) (9) was added to other signal was detected in this experiment (Figure 3).
quench the reactive intermediates, the signal at -496 ppm rapidly was
replaced by three new signals: one at 85 ppm, assigned to benzyl
selenol (6), one at 330 ppm referring to dibenzyl selenide (7) and one
at 401 ppm, assigned to dibenzyl diselenide (8) (Figure 2). These
D
2
3
assignments were supported by the multiplicities of the signals
7
7
D'
observed on the corresponding coupled Se NMR spectra (See
supplementary information). Formation of dibenzyl diselenide (8) was
not expected to occur in a reductive medium. In order to verify if any
oxidation process was taking place, oxygen was bubbled in the NMR
tube for 30 minutes and a new spectrum was acquired. The changes in
signal intensities for benzyl selenol (6) and for dibenzyl diselenide (8)
were not evident, showing that the oxidation process is relatively slow.
Benzyl selenol (6) was still the major compound in the mixture. Figure 3: Se { H} NMR spectra (D) and Se (D’) before addition of a
Compounds 7 and 8 were present in small varying amounts and their 5% NaOH aq. sol. to the NaHSe (3) and (E) and (E’) after addition.
presence was related with the reaction color, where a darker solution
E
E'
7
7
1
77

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3
0
77
1
0
4 2 2
When a ratio of 2:1 equiv. of NaBH (1):Se (2) was used, the only Figure 5. (H) Se { H} NMR spectrum of Se (2) reduction to Na Se
2
6
observable signal was at -496 ppm and its coupled spectra splits into (5). (I) Compound 8 after alkylation. (J) Conversion to 7.
a doublet, indicating Se-H coupling. This shows that the NaBH (1) The fact that Na Se (5) has no detectable signal by Se NMR
excess is not basic enough to promote the second deprotonation. spectroscopy is known and has been described elsewhere.
7
7
4
2
2
2
0, 21
Only
However, when the reaction mixture was treated with two equivalents HSe (3a) specie could be identified and no other selenium negative
of BnCl (9), dibenzyl selenide (7) was exclusively formed. In order to ions were observed. Therefore a freshly prepared Na Se (5) solution
get further information about this reaction, we also performed it in two was acidified with HCl and its Se NMR spectrum was acquired. We
-
2
2
7
7
0
steps. Thus, initial reduction of Se (2) with one equiv. of NaBH
followed by addition of one equiv. of BnCl (9) only furnished benzyl when exploring a very wide spectral window.
selenol (6). Then, addition of a second equivalent of NaBH (1) One last experiment was performed to try to detect the presence of the
4 2 2
(1) were unable to detect any signal for H Se (12) in this system even
4
-
(
(
CARE! Rapid hydrogen evolution) followed by another equiv. of BnCl anion BnSeSe (14). Dibenzyl diselenide (8) was synthesized in a 1
9) yielded dibenzyl selenide (7) as the only product (Figure 4). mmol scale and was isolated in 97% yield using Na Se as a
(1) is basic enough to precursor. 0.1 mmol of compound 8 was reduced with 0.2 mmol of
2
2
Therefore, the above results indicate that NaBH
promote the deprotonation of benzyl selenol (6) but not to deprotonate NaBH
4
7
7
-
4
(1) and the Se NMR acquired to verify the presence of BnSe
NaHSe (3).
(13). No signals were observed. To this solution was added another
0
equivalent of Se (2), forming a limpid and brownish solution (possibly
-
77
1
BnSeSe ) (14). Again, this solution gave no signal in the Se { H}
NMR spectrum. After 5 minutes, another equivalent of BnCl (9) was
added to regenerate BnSeSeBn (8) was obtained as a major product
and trace amounts of benzyl selenide (7) (Figure 6).
F
450
400
350
300
250
200
150
100
50
0
ppm
K
G
L
4
50
400
350
1
300
250
200
150
100
50
0
ppm
7
7
Figure 4: (F) Se { H} NMR spectra of benzyl selenol (6) and (G)
after alkylation yielding (7).
M
7
7
2
.2 Synthesis and SeNMR study of Na
To complete our investigation was necessary to obtain Se
reproducible way. There are two general methods described to
generate Na Se (5) from elemental selenium: a) using a 3:2 ratio of
Se (2):NaBH (1) in ethanol as solvent, yielding a mixture of Na Se
5) and H Se (10) (which was driven off by a stream of an inert gas),
and b) formation of Na Se (4), using NaBH (1), followed by addition
of one more equiv. of Se (2). After generating Na Se (5) using the Scheme 3 displays a summary of all reaction made to detect which
2 2
Se (5) species.
2
-
500
450
400
350
300
250
200
150
100
50
0
ppm
2
in a
77
1
Figure 6. Se { H} NMR spectra (K) showing the reduction of dibenzyl
diselenide (8). (L) Reaction with elemental selenium. (M) Alkylation
2
2
0
4
2
2
-
-
with BnCl (9). BnSe (13a) and BnSeSe (13) does not shows signals in
(
2
77
1
Se { H} NMR spectra
.
2
2
4
0
2
2
7
7
1
first method no signal was observed in the Se { H} NMR spectrum. selenium anion species were in solution after reduction of elemental
However, addition of BnCl (9) rapidly generated a strong signal at 402 selenium. It is worth of note that no polyselenides were trapped or
7
7
ppm, which was assigned to the dibenzyl diselenide (8). Reduction of 8 detected using Se NMR, coupled or decoupled, spectroscopy.
using one equivalent of NaBH (1) followed by addition of one
equivalent of BnCl (9) forms selectively dibenzyl diselenide (7) (Figure
).
4
6
1
)1 NaBH4 (1)
SeH
1
2
)1 NaBH4 (1)
)1 BnCl (9)
5
2)1 BnCl (9)
H
1) 2 NaBH4 (1)
) 2 BnCl (9)
Se
Se0
7
2
1
)2 NaBH4 (9)
400
300
200
100
0
-100
-200
-300
-400
ppm
1)0,6 NaBH4 (1)
)1 BnCl (9)
Se-Se
0
2
2)1 Se (2)
)2 BnCl (9)
8
3
1
)1 NaBH4 (1)
1)1 NaBH4 (1)
I
2
)1 BnCl (9)
-
SeSe-
Se
Se0 (2)
400
300
200
100
0
-100
-200
-300
-400
ppm
13
14
J
Scheme 3. Summary of all selenium anions species that could trapped
and identified in this work.
400
300
200
100
0
-100
-200
-300
-400
ppm

ACCEPTED MANUSCRIPT
4
No signal for polyselenides anions or dibenzylpolyselenides were
1
8b
77
11
detected. Eggert reported the Se NMR shifts for BnSe
x
Bn (x=2-4)
Krief, A., Derock, M.,Tet. Lett, 2002, 43, 3083–3086.
(a) Comasseto, J. V.; Ferreira, J. T. B.; Val Fontanillas, J. A.,
12
and using the specified experimental conditions these higher selenides
were not observed.
J.Organornet. Chem., 1984, 277, 261. (b) Ferreira, J. T. B.;
Comasseto, J. V.; Braga, A. L., Synth.Commun.,1982, 12, 595.
3
. Conclusions.
(
c)Ferraz, H. M. C.; Petragnani, N. Can.J. Chem., 1985, 63, 3216.
13
Martynov, A.V., Monareva, N.S., Larina, L.I., Amosova,
(1). If S.V.,Russian J. Org. Chem., 2013, 49, 943–945.
4
The results shows that the generation of pure NaHSe (3) was very
sensitive to the stoichiometric ratio between Se (2) and NaBH
0
0
14
there is an excess of Se (2), then selenides or diselenides (or a
mixture) were obtained. If NaBH
7) was generated. Either way, the benzyl selenol (6) was always the
Yang, X., Wang, Q. Tao, H. and Xu, H.,J. Chem. Research (S),
4
(1) was in excess, dibenzyl selenide 2002, 160–161.
15
(
de Mello, M.B.M. Clososki, G. C. ,Piovan, L., Oliveira, A.R.M.,
main product when there was a small error in the measurement of J.Organomet. Chem., 2015, 794, 11-16.
1
6
NaBH
equilibrium with NaHSe (3) and is not formed as part of an oxidation
process on extraction. In addition, NaBH (1) is not basic enough to
deprotonate NaHSe (3) but can easily deprotonate benzyl selenol (6),
yielding the corresponding selenolate. For the Na Se (4) alkylation
process, any deviation of the stoichiometry of NaBH (1) used always
4
(1). We also demonstrated that Na
2
Se
2
(4) formation is in
Klayman, D.L. and Griffin, T.S., J. Am. Chem. Soc., 1973, 95,
97-199.
7
1
1
4
McFarlane, W., Wood, R.J., J.C.S. Dalton, 1972, 1397-1402.
18
a) Eggert, H., Nielsen, O., Henriksen, L., J. Am. Chem. Soc.,
986, 108, 8, 1725-1730.; b) Johannsen, I., Eggert, H., J. Am.
Chem. Soc.,1984, 106, 1240-1243.
2
2
1
4
leads to the formation of benzyl selenol (6) in small amounts and
dibenzyl diselenide (8) as the major compound. In a last attempt to
1
9
Bjorgvinsson, M., Schrobilgen, G. J., Inorg. Chem., 1991, 30,
detect a negative selenium ion, (8) was reduced, using the established 2540-2547.
0
20
protocol and one equivalent of Se (2) was added to the resulting
Lyons, L.E., Young, T.L., Aust.J.Chem., 1986, 39, 511-27.
2
1
colorless solution. No signal was observed for the presence of
BnSeSe (13), which after alkylation regenerates the dibenzyl
Cusik, J., Dance, I., Polyhedron, 1991, 10, 2629-2640.
-
22
77
In all Se NMR spectra diphenyl diselenide was used as a
2
-
2-
diselenide (8). It is clear that Se or Se
2
or any other selenium anion
capillary reference.
7
7
1
23
does not give any signal in the Se { H} NMR spectrum although using
an alkylating agent allowed the trapping of several selenium anions in
Reich, H. J., http://www.chem.wisc.edu/areas/reich/handouts/
nmr/se-data.htm, accessed in 10/11/2015.
7
7
solution. Moreover, several insights over the Se NMR chemical shifts
were presented that can help researches in their works in the synthesis
of selenium compounds, been them organic or inorganic ones.
24
Brown, C.A. and Krishnamurthy, S., J. Org. Chem., 1978, 43,
2
731-2732.
25
Selenium species are very sensitive with changes in
electronegativity around the nucleus. Selenium negative species
should have a low frequency while positive species should have a
high frequency shift.
The variations in the Se NMR chemical shift can be attributed
to its medium dependence properties, especially with temperature
changes.
4
. Acknowledgements
We are grateful to the Brazilian funding agencies Fundação Araucária,
CAPES and CNPq for financial support. We are also grateful to the
NMR Center of UFPR for all NMR analyses.
26
77
5
References.
1
2
3
Ujang Tinggi, Environ. Health Prev. Med. 2008, 13(2), 102–108
Junshi Chen, Asia Pac. J. Clin. Nutr. 2012;21(3), 320-326.
Navarro-Alarcon, M. and Cabrera-Vique, C. Sci. Total Environ.,
008, 400, 115–141.
a) Roman, M., Jitarub, P., Barbante, C., Metallomics, 2014, 6,
5—54.; b) Alberto, E. E., do Nascimento, V., Braga, A. L., J. Braz.
.
2
4
2
Chem. Soc., 21 (11), 2032-2041, 2010; c) Nogueira, C. W., Zeni,
G. and Rocha, J. B. T., Chem. Rev. 2004, 104, 6255-6285.
5
Mugesh, G.; DuMont, W. W.; Sies, H., Chem. Rev., 2001, 101,
2
125-2180.
6
Brown, K.M., Arthur J.R., Public Health Nutrition, 2001, 4 (2B),
5
93-599.
7
Kryukov, G.V., Castellano, S., Novoselov, S. V., Lobanov, A. V.,
Zehtab, O., Guigo, R, et al., Science. 2003, 300, 1439–43.
8
2 3
For Na Se in NH : (a) Brandsma, L., Wijers, H.E., Red. Trav.
Chim. Pays-Bas, 1963, 82, 68; (b) Harvey, A.B., Durig, J.R.,
Morrissey., A.C., J. Chem. Phys., 1969, 50, 4949.; c) Denison,
G.H., Condit, P.C., Ind. Eng. Chem., 1949,41, 944. For Na
NH , see Shlyk, Y.N., Bogolyubov, G.M., Petrov, A.A. Zh.
Obshch. Khim., 1968, 38, 1199. Sicianowski, J., Tet. Letters, 2005,
6, 3331–3334.
2 2
Se in
3
4
9
Gladysz, J.A., Hornby, J.L., Garbe, J.E., J. Org. Chem., 1978, 43,
6
, 1204.
1
0
Zhang, Y., Jia, X., Zhou, X., Synth.Commun.,1994, 24(9), 1247-
252.
1

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7
•
•
•
•
An in-depth analysis of inorganic selenide anions Se NMR is reported.
77
Selenium anions species not detected by Se NMR could be trapped by alkylation.
Dialkyl selenides, dialkyl diselenides or alkylselenols were selectively obtained.
77
Se NMR spectra for organic and inorganic selenide anions is reported.