Toward carbohydrate derivatives with a markedly acidic centre: Structures and reactions of selenium(IV) diolates

Article abstract of DOI:10.1002/ejic.200700837

Cyclic selenites, of the general formula (DiolH_-2)SeO, derived from the diols ethane-1,2-diol, propane-1,2-diol, cis-cyclopentane-1,2-diol, cis-cyclohexane-1,2-diol, trans-cyclohexane-1,2-diol, 1,1′-bicyclopentyl- 1,1′-diol, 1,1′-bicyclohexyl-1,1′-diol, propane-1,3-diol, 2,2-dimethylpropane-1,3-diol, 1,1-bis(hydroxymethyl)cyclopropane, 1,1-bis(hydroxymethyl)cyclopentane, 1,4-anhydroerythritol and the methyl glycosides of β-D-ribofuranose, β-D-ribopyranose, α-D- mannopyranose, β-D-xylopyranose have been prepared and characterised by multinuclear NMR spectroscopy and single-crystal X-ray diffraction. Even with the polyfunctional sugar derivatives, oxidation of substrates did not occur. It has been demonstrated that the title compounds are hydrolytically stable at low pH values. Experimental NMR spectroscopy and structural data are consistent with results of density functional calculations and bonding has been analysed by means of natural bond orbital (NBO) theory. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.

Full text of DOI:10.1002/ejic.200700837

FULL PAPER
DOI: 10.1002/ejic.200700837
Toward Carbohydrate Derivatives with a Markedly Acidic Centre:
Structures and Reactions of Selenium(IV) Diolates
[a]
[a]
Peter Klüfers* and Moritz M. Reichvilser
Keywords: Selenium / Carbohydrates / Density functional calculations / X-ray diffraction / Coordination induced shift
Cyclic selenites, of the general formula (DiolH–2)SeO, de-
rived from the diols ethane-1,2-diol, propane-1,2-diol, cis-cy-
clopentane-1,2-diol, cis-cyclohexane-1,2-diol, trans-cyclo-
crystal X-ray diffraction. Even with the polyfunctional sugar
derivatives, oxidation of substrates did not occur. It has been
demonstrated that the title compounds are hydrolytically
hexane-1,2-diol, 1,1Ј-bicyclopentyl-1,1Ј-diol, 1,1Ј-bicyclo- stable at low pH values. Experimental NMR spectroscopy
hexyl-1,1Ј-diol, propane-1,3-diol, 2,2-dimethylpropane-1,3-
diol, 1,1-bis(hydroxymethyl)cyclopropane, 1,1-bis(hydroxy-
methyl)cyclopentane, 1,4-anhydroerythritol and the methyl
and structural data are consistent with results of density
functional calculations and bonding has been analysed by
means of natural bond orbital (NBO) theory.
glycosides of β-D-ribofuranose, β-D-ribopyranose, α-D-man-
nopyranose, β- -xylopyranose have been prepared and char- (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
D
acterised by multinuclear NMR spectroscopy and single-
Germany, 2008)
Introduction
hydrate ester. To evaluate this point, selenium(IV) was cho-
sen as a particularly typical example of a distinctly acidic
and reactive centre. In addition to the general need for a
structure–properties relationship in p-block diolate chemis-
try, the results could be of interest to both preparative
carbohydrate and medicinal chemists. The former may view
the selenite function as a new kind of protective group while
the latter will be able to gain a deeper insight into possible
transport forms of the elements in biological systems.
The first selenious acid dialkyl ester described in litera-
ture, diethyl selenite, was prepared by Michaelis and Land-
mann in 1887 by the reaction of sodium ethanolate with
selenyl chloride and iodoethane with silver selenite.[
Later, the preparation of dialkyl selenites and some cyclic
selenites of diols by the reaction of selenium dioxide with
alcohols in aprotic solvents (benzene, dioxane, cyclohexane)
The chemistry of biomolecular chelates of the p-block
elements is the subject of studies concerning interdisciplin-
ary problems between chemistry, biology and medicine.
Among the p-block elements, basic and amphoteric centres
such as aluminium, gallium and bismuth(III) form hydro-
lytically stable classical Werner-type biomolecular chelates.
An example is citrato-bismuthate, a means by which bis-
muth(III) may be administered as an antibiotic.[1] Biomole-
cular chelates of acidic centres such as silicon and phospho-
rus, on the other hand, are typically esters or amides which,
being derivatives of inorganic acids, are intrinsically prone
to hydrolysis. Examples for both types of p-block element
derivatives include the most abundant class of biomolecules,
the carbohydrates. Numerous carbohydrate and diol deriva-
13]
[
2,3]
[4]
[4]
[5]
tives of boron,
aluminium, gallium, carbon, sili-
[
14–21]
was reported.
Studies concerning alkyl selenites in
[
6–9]
germanium,[6,10] phosphorus,[5] arsenic and bis-
have been prepared and characterised. Among
[5]
con,
protic media were performed by Simon and Paetzold who
[
5,11]
muth
showed that dimethyl selenite (MeO) SeO is quantitatively
2
these, the ester-type compounds are unstable toward hy-
drolysis. As an example, the tetracoordinate diol esters of
orthosilicic acid rapidly hydrolyse at physiological pH, thus
ruling out any significance of simple diol functions as the
formed upon dissolution of selenium dioxide in methanol
[
22]
at room temperature.
In the presence of other alcohols
[
18]
transesterification was observed, whereas the reaction of
dialkyl selenites, including the diol derivative ethylenedioxy-
selenite, both with water and alkali hydroxide solution re-
sults in rapid hydrolysis of the selenious acid esters.[ Ac-
cordingly, all the published work on the synthesis of organyl
unknown cofactors used by silicifying organisms in the
course of silica biomineralisation.[
9,12]
The central question
19]
thus focuses on the relationship between the properties of
the acid and the hydrolytic stability of the respective carbo-
selenites specifies to a greater (the use of SeOCl instead of
2
SeO ) or lesser extent (the azeotropic removal of liberated
2
[
a] Department Chemie und Biochemie, Ludwig-Maximilians-Uni-
versität,
water) the strict absence of water. The most comprehensive
NMR spectroscopic study on dialkyl selenites was per-
Butenandtstraße 5–13 (Haus D), 81377 München, Germany
E-mail: kluef@cup.uni-muenchen.de
Supporting information for this article is available on the
WWW under http://www.eurjic.org or from the author.
[
23]
formed by Denney et al.
The structural analysis of the
selenite of pinacol (2,3-dimethylbutane-2,3-diol) is the only
384
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2008, 384–396

Structures and Reactions of Selenium(IV) Diolates
such analysis of a dialkyl selenite described in the literature Simple Diols
[
24]
to date. Moreover, all this published work deals with sim-
ple diols leaving as a challenging question whether or not
there is a chemistry of the reactive selenium(IV) centre with
polyfunctional biomolecules such as carbohydrates.
The reaction of ethane-1,2-diol (Ethd) with selenium di-
oxide gave (EthdH )SeO (1) as a colourless solid. In agree-
–
2
ment with this formula, both the 77Se and C NMR spec-
tra of the redissolved solid showed only one signal. The
kinetic inertness of the diol esters on the NMR timescale
can be demonstrated by using the related propane-1,2-diol
13
Results and Discussion
77
as a racemic mixture. The Se NMR spectrum showed two
signals and the 13C NMR spectrum showed two signal sets
of different intensities. This observation is consistent with
the presence of syn/anti isomerism with respect to the orien-
tation of the substituent at the diol moiety and the oxy sub-
stituent of the selenium atom in the colourless oily mixture
of (rac-PrpdH )SeO (2). In addition, both syn- and anti-2
form enantiomeric pairs since the diol was used as a race-
mate. Based on NMR assignments of the structurally char-
acterised analogues of this work, anti-2 can be regarded as
the major product. The phenomenon of syn/anti isomerism
that is well-resolved on the NMR time scale dominates the
spectra of almost all the selenious acid esters reported
herein. That the major product is usually the anti isomer
Preliminary experiments showed that cyclic selenites are
present in considerable amounts in methanolic solution de-
spite the predominance of the dimethyl selenite mentioned
1
3
above. Figure 1 shows a C NMR spectrum of a solution
1 ) of equimolar amounts of selenium dioxide and 1,4-
(
–2
anhydroerythritol in methanol. To prevent competition of
alkylenedioxy and methyl ester formation, the selenites de-
scribed in this work were prepared by condensation reac-
tions between selenium dioxide and the corresponding diol
or polyol in aprotic solvents (cyclohexane, dioxane).
Scheme 1 gives an overview of the compounds described in
this work and the corresponding numbering conventions for
NMR signals. Despite the oxidising power of selenium di-
oxide, the preparation method proved to be more general
than might have been expected. Even with carbohydrate de-
rivatives (13–16) no oxidation of the substrate was ob-
served.
was substantiated by the reaction of SeO with cis-cyclo-
2
pentane-1,2-diol (cis-Cptd). Again, a mixture of the syn-
and anti-(cis-CptdH )SeO (3) products was obtained ac-
–2
cording to NMR spectroscopy with the tentative anti form
as the major product. Attempts to produce crystals suc-
ceeded for this diol and, in fact, structural analysis revealed
the excess isomer, anti-3, as the constituent of the crystal.
The molecular structure and metric parameters are depicted
in Figure 2. In the crystal structure of 3, short intermo-
lecular OϪSe dipolar contacts connect the molecules to in-
finite 1D chains along the crystallographic [100] direction.
Accordingly, the reaction of SeO with cis-cyclohexane-
2
1
1
,2-diol (cis-1,2-Chxd) gave a mixture of syn- and anti-(cis-
77
,2-ChxdH )SeO (4) as a colourless solid. The Se NMR
–2
13
spectrum showed the two expected signals and the
C
Figure 1. 13C NMR spectrum of a stoichiometric mixture of 1,4-
NMR spectrum showed two separate signal sets each of
which consists of three lines. Isomers of the syn/anti type
anhydroerythritol (AnEryt) and SeO
2
in methanol.
Scheme 1. Compound numbers and atom-numbering conventions for NMR spectroscopic data.
Eur. J. Inorg. Chem. 2008, 384–396
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385

P. K l üfers, M. M. Reichvilser
FULL PAPER
Figure 2. One of the two symmetrically independent molecules of
anti-(cis-1,2-CptdH–2)SeO in crystals of 3 (40% probability ellip-
soids, hydrogen atoms with arbitrary radii). Interatomic distances
[
Å] and angles [°] (with standard deviations of the last digit in pa-
rentheses): Se1–O10 1.612(2), Se1–O11 1.761(2), Se1–O12
.7712(18); O10–Se1–O11 105.51(11), O10–Se1–O12 102.24(10),
O11–Se1–O12 90.41(9); O11–C11–C12–O12 20.6(3). Puckering pa-
1
Figure 3. One of the four symmetrically independent molecules of
(BptdH–2)SeO in crystals of 6 (40% probability ellipsoids, hydrogen
atoms with arbitrary radii). Interatomic distances [Å] and angles
[°] (with standard deviations of the last digit in parentheses): Se2–
O2 1.607(3), Se2–O31 1.784(3), Se2–O41 1.783(3); O2–Se2–O41
[
27]
rameters
=
of the cyclopentane ring C11–C12–C13–C14–C15: Q
2
C15
0.398(4) Å, φ
2
= 128.1(5)°,
C14
T .
1
02.08(16), O2–Se2–O31 107.33(15), O31–Se2–O41 89.67(13);
O31–C31–C41–O41 44.0(4).
are to be expected for diols that lack C symmetry. Hence
2
SeO and a racemic mixture of trans-cyclohexane-1,2-diol
2
(
trans-Chxd) yielded rac-(trans-1,2-ChxdH )SeO (5) as an
–2
enantiomeric pair. Due to the lack of syn/anti isomerism
77
and the isochronicity of the enantiomers’ signals, the Se
1
3
NMR spectrum shows one signal and the C NMR spec-
trum shows one signal set consisting of six lines only. For
both cyclohexane-derived diols, crystallisation has not yet
succeeded.
Prior to focusing the work on carbohydrate-related sub-
stituents more bulky diols were investigated, particularly in
order to study the effect of steric bulk on the oligomeris-
ation behaviour of the oxyselenium function. Crystallisa-
tion succeeded for two bulky, C -symmetrical 1,2-diols: the
2
1
,1Ј-bicyclopentyl-1,1Ј-diol (Bptd) derivative (BptdH )SeO
–2
7
7
13
(6) showed the expected one Se NMR signal and five
C
NMR signals. The crystal structure contains, unusually,
four symmetrically independent molecules one of which is
shown in Figure 3. The other molecules adopt similar con-
formations with O–C–C–O torsion angles of 44–48°. The
intermolecular contacts (Figure 4) generate two different
types of infinite chains along the [011] axis. In the chains,
both alkylenedioxy and terminal O-atoms establish dipolar
contacts. The somewhat more bulky 1,1Ј-bicyclohexyl-1,1Ј-
Figure 4. Two types of infinite 1D chains along the [011] direction
in the crystal structure of (BptdH–2)SeO (6) (atoms with arbitrary
diol (Bhxd) forms the selenite (BhxdH )SeO (7). Again, radii, hydrogen atoms are omitted for clarity). The braces represent
–
2
7
7
13
one Se NMR signal and six C NMR signals underline the repetition units. Interatomic distances [Å] (with standard devia-
i
i
tions of the last digit in parentheses): Se1–O11 3.208(3), Se1–O71
the diol’s C symmetry. The crystal structure contains two
2
i
i
ii
2
2
3
.840(3), O21–Se4 2.898(3), O21–O71 2.687(4), Se4–O81
2.955(3), Se3–O31 3.029(3), Se3–O61
.512(3). Symmetry codes: –x, 1 – y, 1 – z; –x, –y, –z; x, 1 +
symmetrically independent molecules one of which is
shown in Figure 5. Selenite 7 is the only compound where
the intermolecular contacts do not form an infinite pattern. y, 1 + z; 1 – x, 2 – y, 1 – z; 1 – x, 1 – y, 1 – z; x, 1 + y, z; x,
Instead, isolated tetramers (Figure 6), in which the selenium
atoms are in a highly distorted trigonal-bipyramidal envi-
ronment formed by five oxygen atoms, can be observed.
iv
v
iv
.987(3), Se2–O2
i
ii
iii
iv
v
vi
vii
viii
y, z – 1;
1 – x, 2 – y, 2 – z.
Besides 1,2-chelation, the formation of six-membered signals. Crystallisation succeeded with a dimethyl deriva-
chelate rings that incorporate a 1,3-diol function is a pos- tive: 2,2-dimethylpropane-1,3-diol (Dmpd) yielded
sible bonding pattern for a carbohydrate. In fact, simple (DmpdH )SeO (9), the NMR spectra of which showed one
–
2
77
13
1,3-diols show this chelation pattern on reaction with SeO2.
Se signal and four C NMR signals. Accordingly, a crys-
Hence the parent compound propane-1,3-diol (Prpd) gave tal of 9, an inversion twin in the polar space group Cc with
7
7
(
1,3-PrpdH )SeO (8) as a colourless solid. The Se NMR one molecule in the asymmetric unit, consists of monomeric
–2
1
3
spectrum shows one signal and the C NMR spectrum two molecules that adopt a chair conformation with the ter-
386
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Eur. J. Inorg. Chem. 2008, 384–396

Structures and Reactions of Selenium(IV) Diolates
ture in crystals of 10 (Figure 8) is similar to 9 except that
the cyclopropane ring distorts the tetrahedral environment
at C2. Intermolecular contacts form infinite layers parallel
to the [010] plane. Finally, the 1,1-bis(hydroxymethyl)cyclo-
7
7
pentane derivative (BhmtH )SeO (11) shows one Se
–2
NMR signal and six 13C NMR signals. The analysed crystal
structure of 11 was refined as a pseudo-merohedral twin.
The structure contains two symmetrically independent
molecules one of which is shown in Figure 9. Again the
Figure 5. One of the two symmetrically independent molecules of
(BhxdH–2)SeO in crystals of 7 (50% probability ellipsoids, hydro-
gen atoms with arbitrary radii). Interatomic distances [Å] and
angles [°] (with standard deviations of the last digit in parentheses):
Se1–O1 1.6177(15), Se1–O11 1.7838(16), Se1–O21 1.7768(16); O1–
Se1–O11 101.93(8), O1–Se1–O21 106.82(8), O11–Se1–O21
90.19(7); O11–C11–C21–O21 45.5(2).
Figure 7. Structure of (DmpdH–2)SeO in crystals of 9 (40% prob-
ability ellipsoids, hydrogen atoms with arbitrary radii). Interatomic
distances [Å] and angles [°] (with standard deviations of the last
digit in parentheses): Se–O2 1.611(3), Se–O1 1.768(4), Se–O3
1
9
.775(4); O1–Se–O2 104.5(2), O2–Se–O3 104.13(18), O1–Se–O3
5.96(16).
Figure 8. Structure of (BhmrH–2)SeO in crystals of 10 (50% prob-
ability ellipsoids, hydrogen atoms with arbitrary radii). Interatomic
distances [Å] and angles [°] (with standard deviations of the last
digit in parentheses): Se–O1 1.614(2), Se–O2 1.788(2), Se–O3
1
9
.799(2); O1–Se–O2 104.66(11), O1–Se–O3 102.48(11), O2–Se–O3
5.30(10).
Figure 6. Isolated tetramers in the crystal structure of (BhxdH–2)-
SeO (7) (atoms with arbitrary radii, hydrogen atoms are omitted
for clarity). Interatomic distances [Å] (with standard deviations of
i
the last digit in parentheses): Se1–O1 2.8113(18), Se1–O31i
i
3
3
.4322(16), O1–Se2 3.2417(17), O21–Se2 3.0833(16), Se1–Se1
i
.4443(3). Symmetry codes: 1 – x, – y, 1 – z.
minal oxygen atom in an axial position (Figure 7) and
slightly bent towards the inside of the six-membered ring.
Dipolar contacts concatenate the molecules along the [001]
axis. Structural work was possible on two more C -symmet-
2
ric 1,3-diols and this underlines the tendency of these com-
pounds to form chair-configured 1,3,2-dioxaselenane rings.
Hence, spirocyclic derivatives were obtained by using the Figure 9. One of the two symmetrically independent molecules of
(
BhmtH–2)SeO in crystals of 11 (40% probability ellipsoids, hydro-
related
Bhmr) and 1,1-bis(hydroxymethyl)cyclopentane (Bhmt).
The selenite (BhmrH )SeO (10) not only shows the same
1,3-diols
1,1-bis(hydroxymethyl)cyclopropane
gen atoms with arbitrary radii). Interatomic distances [Å] and
angles [°] (with standard deviations of the last digit in parentheses):
Se2–O2 1.602(4), Se2–O21 1.758(4), Se2–O23 1.769(4); O2–Se2–
(
–
2
number of NMR signals as 9 but also the molecular struc- O21 105.4(2), O2–Se2–O23 104.85(19), O12–Se2–O23 95.75(16).
Eur. J. Inorg. Chem. 2008, 384–396
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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387

P. K l üfers, M. M. Reichvilser
FULL PAPER
conformation is similar to that of 9. Actually, the type of
intermolecular contacts is the same, that is, infinite chains
along the [001] axis.
A closer approach to carbohydrates was made by using
1,4-anhydroerythritol (AnEryt) as a furanoidic 1,2-diol.
Due to the lack of C -symmetry, syn/anti isomerism was
2
expected. Thus surprisingly, the reaction of SeO2 and
AnEryt led to only one product, the anti isomer of
(
AnErytH )SeO (12), according to NMR spectroscopy.
–2
The molecular structure is shown in Figure 10. The fu-
ranoidic ring adopts an envelope conformation on O4. The
molecular packing is dominated by short intermolecular
OϪSe contacts that lead to the formation of infinite two-
dimensional layers parallel to the crystallographic [001]
plane.
Figure 11. Structure of the anti-(Me-β--Ribf2,3H–2)SeO mole-
cules in crystals of 13 (major disorder component, 50% probability
ellipsoids, hydrogen atoms with arbitrary radii). Interatomic dis-
tances [Å] and angles [°] (with standard deviations of the last digit
in parentheses): Se–O6 1.6098(18), Se–O2 1.7800(18), Se–O3
1
8
.7849(17); O2–Se–O6 103.39(9), O3–Se–O6 104.46(10), O3–Se–O2
7.55(8); O2–C2–C3–O3 8.1(3). Puckering parameters[ of the fu-
27]
ranose ring O4–C1–C2–C3–C4: Q
T .
O4
2
2
= 0.277(3) Å, φ = 194.4(6)°,
C1
diol-derived selenium compounds. However, despite this
variability, the 1,2-diol-derived products syn- and anti-(Me-
β--Ribp3,4H )SeO (14) were obtained in an isomeric ra-
–
2
77
tio of 3:7 (syn:anti). The Se NMR spectrum thus shows
two signals and the C NMR spectrum shows two signal
Figure 10. Structure of the anti-(AnErytH–2)SeO molecules in crys-
tals of 12 (50% probability ellipsoids, hydrogen atoms with arbi-
trary radii). Interatomic distances [Å] and angles [°] (with standard
13
sets. Attempts to confirm this result by structural analysis
deviations of the last digit in parentheses): Se–O1 1.6046(16), Se– led only to a preliminary X-ray analysis on crystals of poor
O2 1.7749(17), Se–O3 1.7781(15); O1–Se–O2 105.55(9), O1–Se–O3 quality. However, the assignment of a selenite group
1
04.18(8), O2–Se–O3 88.32(7); O2–C2–C3–O3 8.2(2). Puckering
bonded to O3 and O4 instead of O2 and O3 could be
clearly confirmed.
The rules of the chelation of the divalent SeO core by a
carbohydrate-derived chelator became more transparent af-
ter the reaction of two more methyl pyranosides that pro-
vide cis- and trans-1,2-diol functions as well as potential
[
27]
parameters
2
of the furanoidic ring O4–C1–C2–C3–C4: Q =
O4
2
0.3882(19) Å, φ = 351.4(3)°, E.
Carbohydrates
1
,3-chelators. Thus methyl α--mannopyranoside (Me-α--
The reaction of selenium dioxide and methyl β--ribofur-
anoside (Me-β--Ribf) in dioxane gave a mixture of syn-
and anti-(Me-β--Ribf2,3H )SeO (13). The mixture shows
two Se NMR signals and two C NMR signal sets. Crys-
tallisation succeeded and resulted in the isolation of the anti
isomer as the major component. Figure 11 shows the mo-
lecular structure of anti-13. The isomeric molar ratio of the
Manp) gave syn- and anti-(Me-α--Manp2,3H )SeO (15).
–2
The 77Se NMR spectrum shows two signals and the
13
C
–
2
7
7
13
NMR spectrum shows two signal sets. In the case of
methyl-β--xylopyranoside (Me-α--Xylp) four products
were obtained: syn- and anti-(Me-β--Xylp2,3H )SeO
–2
(
(
16a) as well as syn- and anti-(Me-β--Xylp3,4H )SeO
–2
16b). The 77Se NMR spectrum shows four signals. Com-
solutions was 3:2. The furanose ring adopts a twist confor-
C1
paring the chemical shift values with those of the previously
described compounds leads to the assumption that anti-16a
and anti-16b are the predominant species.
mation ( TO4) and the CH OH function takes part in hy-
2
drogen bonding and is disordered. In the minor disordered
component (ca. 30%, not shown in Figure 11), an intramo-
lecular hydrogen bond from the O5 donor to the O1 ac-
ceptor is established. Instead, in the major component the
O5-hydroxy group acts as a donor in intermolecular hydro-
gen bonding. Together with the intermolecular dipolar con-
Structural Parameters
The structures of five- and six-membered cyclic selenites
tacts between SeϪO functions, they form an infinite 3D throughout show Se–Oterminal bond lengths of 1.60–1.61 Å
framework, the hydrogen-bonded part generating chains and Se–Odiol bond lengths of 1.78–1.80 Å. The exocyclic O–
along the [100] direction.
Se–O angles are about 105°. In five-membered selenites the
As with the ribofuranoside, methyl β--ribopyranoside endocyclic O–Se–O angles are in the region of 90°, whereas
Me-β--Ribp) allows the formation of either 1,2- or 1,3- in six-membered rings this angle is larger at about 96°.
(
388
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Structures and Reactions of Selenium(IV) Diolates
Hydrolysis
bered selenites with 1,3-diol functions, though sterically
possible, was not observed. In all cases five-membered rings
formed. Since syn- and anti-15 are the sole products of the
reaction with methyl α--mannopyranoside, it is clear that
there is a general preference for cis-1,2-diol groups. How-
ever, in a preliminary experiment with two equiv. of SeO2,
it was possible to obtain a six-membered selenite with ester-
ified O4 and O6 additionally. Methyl β--xylopyranoside
bears two vicinal trans-diol functions, both of which take
part in the formation of selenites. Hence, the selenium(IV)
atom is clearly able to participate in trans-pyranoidic che-
Compounds such as 12 form in a methanolic solution at
equilibrium with molar amounts of liberated water (Fig-
ure 1). Hence, the alkylene selenites of this work are clearly
not unstable towards hydrolysis in a narrower sense. How-
ever, the title compounds are hydrolysed in pure aqueous
media. Experiments were carried out with selected com-
pounds, namely the cyclic selenites of cis-cyclopentane-1,2-
diol (3), 2,2-dimethylpropane-1,3-diol (9), 1,4-anhydroer-
ythritol (12) and methyl β--ribofuranoside (13). In all
cases complete hydrolysis was observed in acidic (1 
H SO , 1  HCl, 0.1  HCl), neutral (pure water, no buffer)
[
9]
late rings, an ability that silicon is lacking.
2
4
The observations can be summarised as follows: in the
case of furanoidic and pyranoidic diol functions, cyclic sele-
nites are preferentially formed with cis-1,2-diol functions
instead of 1,3-diol or pyranoidic trans-1,2-diol functions.
The latter, however, are both able to form cyclic selenites in
the absence of cis-1,2-diol functions.
and basic (1  and 0.1  NaOH) aqueous media.
These findings could be partly anticipated. In neutral
and basic solution, on the one hand, where resonance-stabi-
lised selenite anions are formed, rapid and complete hydrol-
ysis is a typical reaction of a strong acid’s ester. In acidic
media, on the other hand, at pH values below pK of sele-
nious acid H SeO at 2.6, the non-deprotonated H SeO3
a1
[25]
2
3
2
molecule is the competitor of the diol ester. Using the ex-
perience from coordination chemistry that a diolato com- NMR Data
plex has a good chance of being formed if this chelating
Coordination induced shifts (CIS) of 13C NMR signals
dianion replaces two hydroxido ligands, the fact that com-
plete hydrolysis was observed was not regarded as compel-
ling. The experimental setup was thus extended to an ex-
traction technique in order to also detect smaller equilib-
rium concentrations of the ester than by a direct NMR
analysis.
related to the signals of the free diols together with 77Se
NMR chemical shifts of 1–14 are given in Table 1. While in
selenites of 1,2-diols, the NMR signals of the α carbon
atoms are invariably shifted to lower field by up to 17 ppm,
the corresponding signals in derivatives of 1,3-diols gain a
high-field shift of 1–4 ppm. In the case of 77Se NMR spec-
tra, one can observe the selenium signals in six-membered
Aqueous solutions to be extracted were prepared from
SeO and a molar amount of diol at a total selenium con-
2
–
1
centration of 1 molL . The reaction mixture was heated
to 70 °C for 2 h and, after cooling, the aqueous phase was
extracted with dichloromethane and the organic phase was
Table 1. Observed (δobs) and calculated (δcalc) NMR chemical shifts
analysed by NMR spectroscopy. As a result, the alkylene of the selenium and α carbon nuclei (connectivity C –O–Se–O–
α1
C
α2). All spectra were recorded in CDCl
3
except that of 14 which
selenites derived from pinacol and anhydroerythritol were
detected in the apolar solvent. By keeping the pH value
sufficiently low, alkylene selenites may therefore be pre-
pared from an aqueous solution. It remains to be investi- are given in ppm. No CIS values are given for compound 13 due
gated whether there are carbohydrate-derived diol functions to the lack of comparative data.
was recorded in [D ]DMSO. Calculated shifts are corrected accord-
6
ing to the linear correlations given in Figures 13 and 14. The coor-
dination induced shift (CIS) is calculated as δproduct – δdiol. All data
that provide sufficiently high stability to the tentative che-
late “complexes” to enrich the selenite ester to a higher
quantity even in the aqueous solution itself.
77Se
δobs
13Cα1
δobs
13Cα2
δobs δcalc CIS
δcalc
δcalc CIS
1
2
1430 1434
1438 1453
anti 1432 1431
syn 1481 1468
anti 1463 1465
syn 1445 1440
70.5 69.4 +6.7
74.6 74.9 +6.8
75.9 75.3 +8.1
91.2 92.3 +17.3
88.1 88.1 +14.3
81.0 80.7 +10.4
79.7 78.7 +9.1
87.1 85.2 +7.3
100.8 99.3 +13.7
92.6 90.9 +17.0
59.1 57.2 –2.6
68.3 66.5 –2.8
66.5 64.5 –1.5
67.0 65.6 –3.6
87.2 89.1 +15.9
93.4 93.3
syn
80.9 80.4 +12.6
78.4 76.8 +10.1
syn/anti-Isomerism and Regioselectivity
3
4
Due to the high inversion barrier of the pyramidal SeO3
group, syn/anti isomerism occurs unless the diols are C2-
symmetric. The only observed exception occurred in the
case of 1,4-anhydroerythritol, where the anti isomer was the
sole product of the reaction with selenium dioxide in boil-
ing cyclohexane. In methanolic solution, however, both iso-
anti 1424 1438
1407 1407
5
6
7
8
9
1
1
1
1
83.1 81.2 +3.3
1407 1412
1409 1404
1301 1300
1285 1290
1295 1294
1289 1289
0
1
2
3
mers were formed in equilibrium with (MeO) SeO (Fig-
2
ure 1). It is unclear whether the syn isomer is thermody-
namically less stable in the nonpolar and nonprotic solvent
or whether the anti isomer is the kinetic product.
In the reactions of carbohydrates with equimolar
amounts of selenium dioxide, the formation of six-mem-
anti 1492 1507
syn
anti 1481 1489
syn 1454 1452
anti 1459 1431
1492 1495
90.0 90.4
87.9 88.2
76.7 78.1 +9.4
75.3 75.3 +7.9
91.0 92.2
78.6 85.4 +7.9
77.4 77.5 +6.8
14
Eur. J. Inorg. Chem. 2008, 384–396
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
389

P. K l üfers, M. M. Reichvilser
FULL PAPER
rings in a narrow range around 1295 ppm. In five-mem-
bered rings the signals are located at 1400–1500 ppm. From
the data it is evident that both the α carbon CIS values and
the 7 Se shifts allow unambiguous assignment of whether
the SeO group is coordinated by a 1,2- or a 1,3-diol func-
tionality in polyols thus making the combined NMR spec-
troscopy a valuable tool for the assignment of carbohydrate
bonding modes towards selenium(IV).
7
DFT Calculations
Geometrical Parameters
Structural optimisations were performed at the B3LYP/
6-31+G(2d,p) level of theory for 1–14. Theoretically derived
bond lengths and O–Se–O angles are practically identical
to the experimental data from the X-ray structure analyses.
The only significant differences concern the O–C–C–O tor-
sion angles in 3 and 12. While the X-ray structures show
torsion angles of up to about 20°, the calculations (al- 6-311++G(2d,p)] and observed (δobs
Figure 13. Linear correlation between calculated [δcalc, PBE1PBE/
1
3
)
C NMR chemical shifts. In-
cluded are data of compounds 1–14 (both syn- and anti-isomer if
though symmetry was turned off) predict almost perfect
planarity. As can be seen from an energy profile of the O–
C–C–O torsion in 3 (Figure 12), the total energy in the gas
phase depends only slightly on the actual torsion angle.
Hence, it can be assumed that the angle in the solid state
adjusts so that an optimisation of (basically dipolar) inter-
molecular contacts is achieved.
existent). The correlation is described by the linear equation
1
3
13
δ
obs( C)/ppm = 0.984(7) · δcalc( C)/ppm – 2.4(5).
Figure 12. Total energy [B3LYP/6-31+G(2d,p), with an ultra-fine
integration grid and very tight convergence criteria] of anti-(cis-1,2-
CptdH–2)SeO (3) as a function of the O–C–C–O torsion angle.
Figure 14. Linear correlation between calculated [δcalc, PBE1PBE/
7
7
6
-311++G(2d,p)] and observed (δobs
)
Se NMR chemical shifts.
Included are data of compounds 1–14 (both syn- and anti-isomer
NMR Data
if existent). The correlation is described by the linear equation
7
7
77
2
NMR chemical shift calculations were performed at the
PBE1PBE/6-311++G(2d,p) level of theory on the B3LYP/
δobs( Se)/ppm = 0.83(3) · δcalc( Se)/ppm + 2.6(4) ϫ 10 .
6
-31+G(2d,p)-optimised structures and referenced to Me Si
4
and Me Se data which were calculated by the same method.
δobs(13C)/ppm = 0.984(7) · δcalc(13C)/ppm – 2.4(5)
2
The shift values of nuclei which are symmetrically equiva-
lent in solution were averaged. Figure 13 shows the corre-
This clearly allows NMR signal assignment based on calcu-
lated values. The correlation for 77Se NMR shifts (see the
following equation and Figure 14) is less accurate.
1
3
lation between calculated and observed C NMR chemical
shifts for 1–14. The linear dependence is best described by
the following equation.
77
δ
obs( Se)/ppm = 0.83(3) · δcalc(77Se)/ppm + 2.6(4) ϫ 102
390
www.eurjic.org
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim Eur. J. Inorg. Chem. 2008, 384–396

Structures and Reactions of Selenium(IV) Diolates
NBO Analyses
the high positive natural charge on Se the intermolecular
contacts described above can be understood as Lewis acid-
base interactions where Se is the Lewis acid.
The bonding situation in the described compounds was
analysed by means of natural bond orbital (NBO)
IV
[
26]
Subfigure 15g illustrates the overlap between a p type
lone pair at the exocyclic oxygen atom and one of the two
endocyclic σ*(Se–O) orbitals. A second-order-perturbation-
theory analysis performed with the NBO program package
shows that this overlap gives rise to a two-electron stabilisa-
theory.
The results are very similar for all compounds
with 1,2- and 1,3-diols, respectively. Therefore the results
obtained for 1 and 8 which are discussed in the following
are representative for all compounds.
In the five-membered ring of 1 as well as in the six-mem-
bered ring of 8 the selenium atom bears a positive natural
charge of +1.9. The exocyclic oxygen atoms bear a natural
charge of –1.0 and the endocyclic ones a charge of –0.8. In
agreement with the calculated and observed endocyclic O–
Se–O angles, the selenium contribution (natural hybrid or-
bital, NHO) to the Se–O single bonds in 1 has a slightly
higher p character than in the case of 8. In all cases, d
orbital contributions are negligible. Numerical values are
provided in Table 2.
–1
tion energy of 51 kJmol . Actually, the interactions be-
tween the second p type lone pair (not shown in the Figure)
and the σ*(Se–O) orbitals lead to stabilisation energies of
–1
7
6 kJmol . Therefore the exocyclic Se–O bonds in dialkyl-
selenites can be described by a σ bond and a set of four
negative hyperconjugations between filled n orbitals (two
π
p type lone pairs) and the adjacent σ*(Se–O) orbitals. From
the results of the NBO analysis it is clear that the Lewis
structure in Figure 16 (a) does not give an appropriate de-
scription of the real bonding situation in dialkyl selenites.
The alternative dipolar structure (Figure 16, b) does not
take into account that the bond orders of endocyclic and
exocyclic Se–O bonds differ by a factor of about two. For
a correct description of both charges and bond orders a
resonance (Figure 16, e) between the formulae in Fig-
ure 16 (a–d) may be considered.
Figure 15 shows isocontour plots of selected natural
bond orbitals of 8. Subfigures b and d show the valence-
shell lone pair at the selenium atom. The predominant s
character (about 70%, Table 2) is apparent. Together with
Table 2. Selected results of DFT calculations and NBO analyses
for compounds 1 and 8.
1
8
bond lengths [Å] Se=O
Se–O
1.611
1.813
1.620
1.795
105.4
95.3
1.808
108.4
1.795
105.5
bond angles [°]
O–Se=O 104.5
O–Se–O 88.9
NBO charges
–0.79
–0.79
5
1
0
.66
5.91
NHO at Se
sp11.55
Figure 16. Resonance structures for 8.
Figure 15. Isocontour plots of selected natural bond orbitals in 8. Isolines are drawn at 0.03, 0.08, 0.13 and 0.18. Crossed circles indicate
atoms in the drawing plane. (a) Se–O bonding σ orbital, (b) lone pair on Se, (c) Se–O antibonding σ* orbital, (d) lone pair on Se, (e)
lone pair on terminal oxygen atom, (f) Se–O antibonding σ* orbital, (g) negative hyperconjugation between (e) and (f).
Eur. J. Inorg. Chem. 2008, 384–396
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
391

P. K l üfers, M. M. Reichvilser
FULL PAPER
1
6
7.9 MHz, 77Se: 51.5 MHz) and Jeol Eclipse 400 ( H: 400 MHz,
Conclusions
1
3
77
C: 101 MHz, Se: 76.2 MHz) NMR spectrometers. The signals
of the deuterated solvent ( C) and the residual protons therein
H) were used as an internal secondary reference for the chemical
Well-defined carbohydrate derivatives of selenium(IV)
form in agreement with the stereochemical properties of the
13
1
(
7
7
carbohydrate’s selenium-binding site. It was shown that this shift. Se shifts were referenced to external Me Se in CFCl . If
2
3
1
13
binding site can be determined unambiguously by means of necessary, H and C NMR signals were assigned by means of
1
1
1
13
1
13
the coordination-induced shift (CIS) of NMR signals. The routine H- H-COSY45, DEPT135, H- C-HMQC and H- C-
HMBC experiments. Ratios of isomers were determined from suit-
basis of an unusually reliable structure–CIS correlation is a
1
able H integrals where possible. The abbreviations “a” (anti) and
perfect match between experimentally observed and theore-
“
s” (syn) are used in the assignment of NMR signals.
tically derived chemical shift values.
The analyses of the bonding situation showed that there Infrared Spectra: Jasco FTIR 460 Plus spectrometer equipped with
a PIKE MIRacle ATR unit.
are, as is usual in p-block chemistry, no significant contri-
butions of selenium d orbitals. The shape and extension of
Crystal Structure Determination and Refinement: Crystals suitable
the valence-shell lone pair of selenium in the alkylene sele- for X-ray crystallography were selected with the aid of a polarising
nites are dominated by an s character of about 70%. Ac- microscope, mounted on the tip of a glass fibre and investigated at
cordingly, the endocyclic O–Se bonds are mostly of p char- 200(2) K on a Nonius KappaCCD diffractometer with graphite-
monochromated Mo-K
were solved by Patterson methods (SHELXS-97 ) and refined by
α
radiation (λ = 0.71073 Å). The structures
acter which results in endocyclic O–Se–O angles of about
0°. The oxyselenium(IV) core thus provides a binding site
[32]
9
2
[32]
full-matrix, least-squares calculations on F (SHELXL-97 ). Hy-
drogen atoms were included in idealised positions with one com-
mon isotropic displacement parameter refined. Anisotropic dis-
placement parameters were refined for all non-hydrogen atoms.
Multi-scan absorption corrections were performed with
that matches the relatively small bite of an alkylenedioxy
substituent. This substituent, in coordination chemistry ad-
dressed as a diolato ligand, provides unstrained chelate
rings either for small tetrahedral centres such as carbon or
boron or for centres that demand bonding at about right
[33]
or SADABS.[34] Crystallographic data are listed
SCALEPACK
angles: octahedral centres, axial-equatorial pairs of trigonal in Tables 3 and 4. Publication material was prepared with
[
35]
[36]
bipyramids, or, in this work, a low-coordinate centre the PLATON and ORTEP-III
bonding directions of which are p orbital dominated.
.
CCDC-647110 (for 3), -647111 (for 6), -647112 (for 7),
647113 (for 9), -647114 (for 10), -647115 (for 11), -647116 (for
2), -647117 (for 13) contain the supplementary crystallographic
Taking together the predominant s character of the sele-
nium’s lone pair and a natural charge of about +2, the sele-
-
1
nium centre is a typical Lewis acid which has been recog- data for this paper. These data can be obtained free of charge from
nised from the crystal structure’s packing principles of the The Cambridge Crystallographic Data Centre via www.ccdc.cam.
[
24]
ac.uk/data_request/cif.
pinacol derivative.
Keeping in mind the issue of the hydrolytic sensitivity of
General Procedure for Selenite Synthesis: A stirred suspension of
a p-block centre–biomolecule chelate, the most significant equimolar amounts of selenium dioxide and the diol in cyclohexane
property of the selenites reported herein is that rapid hy- or dioxane (40 mL) was heated to reflux at a water trap for 1–8 h.
drolysis is restricted to pH values larger than the acidity The solvent was distilled and the crude product was freed from
traces of solvent under reduced pressure. Unless otherwise stated,
this method afforded products of analytical purity. Crystals for X-
ray structure analyses were grown by recrystallisation from cyclo-
hexane or chloroform.
constant of selenious acid. Moreover, an aqueous solution
of unprotolysed (HO) SeO is a suitable starting material for
2
the formation of diol esters, that is, for the replacement of
two hydroxy groups by a single alkylenedioxy substituent in
favour of the chelate effect. The hydrolytic equilibrium thus (EthdH–2)SeO (1): Prepared from ethane-1,2-diol (1.24 g,
2
0.0 mmol) and selenium dioxide (2.22 g, 20.0 mmol) in cyclohex-
appears to be correlated with and controllable by the acid’s
protonation state.
ane according to the general procedure. Pure 1 (2.94 g, 19.0 mmol,
9
6
NMR (270 MHz, CDCl
AAЈBBЈ pattern) ppm. C NMR (67.9 MHz, CDCl
5%) was immediately obtained as a colourless powder. M.p. 65–
Supporting Information (see also the footnote on the first
page of this article): Additional figures (intermolecular con-
7
7
1
7 °C. Se NMR (51.5 MHz, CDCl
3
, 26 °C): δ = 1430 ppm. H
3
13
, 24 °C): δ = 4.72–4.30 (m, characteristic
7
7
tacts in 3, 9, 10 and 11. Se NMR spectrum of 16) and
3
, 26 °C): δ =
tables (NBO analyses).
7
8
0.5 ppm. IR: ν˜ = 2956, 2897, 1447, 1331, 1206, 1017, 917,
–
1
+
82 cm . MS (DCI , isobutane) m/z calcd. for C
2
H
5
O
3
Se [M +
pattern. C Se
155.01): calcd. C 15.50, H 2.60; found C 15.71, H 2.60.
+
H] 156.9; found: 157.0 with a characteristic Se
(
1
2 4 3
H O
Experimental Section
Quantum Chemical Calculations: Performed with GAUSSIAN
(
(
rac-1,2-PrpdH–2)SeO (2): Prepared from rac-propane-1,2-diol
1.52 g, 20.0 mmol) and selenium dioxide (2.22 g, 20.0 mmol) in cy-
[
28]
[26]
03
and NBO 5.0.
Materials: Reagent-grade chemicals were purchased from Fluka,
Sigma Aldrich and Acros and used as supplied. Methyl β--
ribopyranoside was obtained from Glycon Biochemicals. 1,1Ј-Bicy-
clohexane according to the general procedure. Pure 2 (3.16 g,
8.7 mmol, 93%), a mixture of four isomers, was immediately ob-
1
77
tained as a colourless oil. Se NMR (76.2 MHz, CDCl
=
δ = 5.06–4.93 (m, 1 H
3
, 25 °C): δ
1438 (syn), 1432 (anti) ppm. H NMR (400 MHz, CDCl , 23 °C):
; HC2a), 4.72–4.63 (m, 1 Ha; HC1a), 4.60–
; HC2s), 4.23–4.15 (m, 1 H
; HC1a), 1.52–1.46 (m, 3 H ; HC3s), 1.40–
; HC3a) ppm. 13C NMR (101 MHz, CDCl
, 25 °C): δ
[
29]
[30]
clohexyl-1,1Ј-diol,
1,1-bis(hydroxymethyl)cyclopentane
and
1
3
methyl β--ribofuranoside[ were prepared according to literature
31]
a
procedures.
4
.54 (m, 1 H
HC1s), 3.88–3.75 (m, 1 H
1.36 (m, 3 H
s
; HC1s), 4.53–4.45 (m, 1 H
s
s
;
NMR Spectra: All measurements were performed at room tempera-
a
s
1
13
ture. Spectrometers: Jeol Eclipse 270 ( H: 270 MHz,
C:
a
3
392
www.eurjic.org
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2008, 384–396

Structures and Reactions of Selenium(IV) Diolates
Table 3. Crystallographic data for 3, 6, 7 and 9.
3
6
7
9
CCDC number
647110
647111
647112
647113
C H10OSe
5
Empirical formula
C
5
H
8
O
3
Se
C
10
H
16
O
3
Se
C
12
H
20
O
3
Se
–
1
M
r
[gmol ]
195.07
0.30ϫ0.10ϫ0.04
263.19
0.18ϫ0.04ϫ0.02
291.24
0.15ϫ0.09ϫ0.05
197.09
0.19ϫ0.07ϫ0.01
monoclinic
Cc
6.1588(5)
18.6338(12)
6.5158(4)
90
102.276(4)
90
730.67(9)
4
Crystal size [mm]
Crystal system
Space group
a [Å]
b [Å]
c [Å]
α [°]
β [°]
triclinic
triclinic
triclinic
¯
¯
¯
P1
P1
P1
6.6558(2)
9.3066(3)
11.4501(4)
94.1200(19)
105.988(2)
98.352(2)
669.91(4)
4
12.7738(4)
13.8258(5)
14.4208(6)
112.8430(10)
101.086(2)
104.292(2)
2152.83(15)
8
9.5109(3)
11.3210(3)
12.2766(3)
82.8335(16)
79.8575(17)
74.1210(15)
1247.45(6)
4
γ [°] 3
V [Å ]
Z
–3
Calcd. density [gcm ]
1.9342(1)
5.535
1.6241(1)
3.468
1.5507(1)
3.001
1.7917(2)
5.075
–
1
µ [mm ]
Absorption correction
Transmission factor range
Reflections measured
multi-scan
0.502–0.801
20796
0.0544
0.0359
3.23–27.57
2410
0.0261, 0.3694
–
3067
164
multi-scan
–
17522
0.0384
0.0601
3.24–27.59
7165
0.0587, 1.7359
–
multi-scan
–
10697
0.0307
0.0430
3.28–27.45
4529
0.0327, 0.4708
–
multi-scan
–
1569
0.0230
0.0376
3.56–27.49
1391
0.0403, 1.0458
0.50(2) (inv. twin)
1561
R
int
Meanσ(I)/I
θ range
Observed reflections
x, y (weighting scheme)
Flack parameter
Reflections in refinement
Parameters
9835
506
5655
290
87
Restraints
0
0
0
2
R(Fobs
)
0.0281
0.0632
1.033
0.0470
0.1231
1.006
0.0319
0.0768
1.034
0.0347
0.0828
1.084
2
R
S
w
(F )
Shift/errormax
0.001
0.493
–0.566
0.001
0.794
–0.696
0.001
0.401
–0.603
0.001
0.554
–0.501
–
–3
Max. e density [eÅ ]
–
–3
Min. e density [eÅ ]
=
80.9 (C2s), 78.4 (C2a), 75.9 (C1a), 74.6 (C1s), 17.4 (C3s), 16.9 (101 MHz, CDCl
3
, 24 °C): δ = 81.0 (C1s,2s), 79.7 (C1a,2a), 28.8
(C3s,6s), 28.1 (C3a,6a), 20.8 (C4s,5s), 20.5 (C4a,5a) ppm. MS (DCI+,
isobutane) m/z calcd. for C
Se [M + H]+ 211.0; found 211.1
with a characteristic Se pattern. C Se (209.10): calcd. C
4.46, H 4.82; found C 34.36, H 4.78.
+
(C
3a) ppm. MS (DCI , isobutane) m/z calcd. for C
3
H
7
O
3
Se [M +
Se
+
H] 171.0; found 171.0 with a characteristic Se
1
pattern. C
3
H
6
O
3
6 11 3
H O
(169.04): calcd. C 21.32, H 3.58; found C 21.23, H 3.54.
1
6 10 3
H O
3
(cis-1,2-CptdH–2)SeO (3): Prepared from cis-cyclopentane-1,2-diol
(
3.07 g, 30.1 mmol) and selenium dioxide (3.34 g, 30.1 mmol) in cy-
(rac-trans-1,2-ChxdH–2)SeO (5): Prepared from rac-trans-cyclohex-
ane-1,2-diol (2.32 g, 20.0 mmol) and selenium dioxide (2.22 g,
20.0 mmol) in cyclohexane according to the general procedure.
clohexane according to the general procedure. Pure 3 (5.72 g,
9.3 mmol, 97%), a mixture of two isomers (anti/syn 3:1), was im-
2
77
mediately obtained as a colourless crystalline solid. Se NMR
Pure 5 (3.97 g, 19.0 mmol, 95%) was immediately obtained as a
1
77
(
51.5 MHz, CDCl
NMR (400 MHz, CDCl
.17 (m; HC1s,2s), 2.32–1.60 (m) ppm. 13C NMR (67.9 MHz, CDCl
CDCl , 27 °C): δ = 91.2 (C1s,2s), 88.1 (C1a,2a), 33.7 (C3s,5s), 32.8 2.19 (m, 2 H), 1.95–1.79 (m, 2 H), 1.76–1.61 (m, 1 H), 1.59–1.46
3
3a,5a), 22.1 (C4a), 21.7 (C4s) ppm. MS (DCI , isobutane) m/z (m, 1 H), 1.44–1.17 (m, 2 H) ppm. C NMR (101 MHz, CDCl ,
3
, 26 °C): δ = 1481 (syn), 1463 (anti) ppm.
, 23 °C): δ = 5.43–5.38 (m; HC1a,2a), 5.22– (76.2 MHz, CDCl
, 22 °C): δ = 4.18–4.05 (m, 1 H), 3.67–3.54 (m, 1 H), 2.39–
H
colourless crystalline solid. M.p. 69.4–70.7 °C.
Se NMR
1
3
3
, 24 °C): δ = 1407 ppm. H NMR (400 MHz,
5
3
3
+
13
(
C
+
calcd. for C
istic Se pattern. C
C 30.84, H 4.01.
5
H
9
O
3
Se [M + H] 197.0; found 197.1 with a character-
25 °C): δ = 87.1, 83.1, 30.7, 29.8, 23.9, 23.7 ppm. IR: ν˜ = 2927,
1
5
H
8
O
3
Se (195.08): calcd. C 30.78, H 4.13; found
2861, 1453, 1447, 1360, 1091, 1029, 1011, 932, 912, 882, 848, 837,
–
1
+
796, 653, 643 cm . MS (DCI , isobutane) m/z calcd. for
Se [M + H]+ 211.0; found 211.2 with a characteristic Se
pattern. C Se (209.10): calcd. C 34.46, H 4.82; found C
4.64, H 4.81.
C
6
H
11
O
3
1
(cis-1,2-ChxdH–2)SeO (4): Prepared from cis-cyclohexane-1,2-diol
6
10 3
H O
(1.16 g, 10.0 mmol) and selenium dioxide (1.11 g, 10.0 mmol) in cy-
3
clohexane according to the general procedure. Pure 4 (1.98 g,
.47 mmol, 95%), a mixture of two isomers, was immediately ob-
9
(BptdH–2)SeO (6): Prepared from 1,1Ј-bicyclopentyl-1,1Ј-diol
(3.41 g, 20.0 mmol) and selenium dioxide (2.22 g, 20.0 mmol) in cy-
clohexane according to the general procedure. Pure 6 (5.10 g,
77
tained as a colourless crystalline solid. Se NMR (76.2 MHz,
1
CDCl
3
, 24 °C): δ = 1445 (syn), 1424 (anti) ppm. H NMR
400 MHz, CDCl
m; HC1s,2s), 2.04–1.93 (m; HC3s,6s), 1.82–1.69 (m; HC3a,6a and
(
(
3
, 22 °C): δ = 4.68–4.62 (m; HC1a,2a), 4.40–4.34 19.4 mmol, 97%) was immediately obtained as a colourless crystal-
7
7
3
line solid. M.p. 75.0–75.9 °C. Se NMR (51.5 MHz, CDCl ,
1
HC3s,6s), 1.64–1.54 (m; HC3a,6a), 1.54–1.47 (m; HC4s,5s), 1.45–1.34 26 °C): δ = 1407 ppm. H NMR (270 MHz, CDCl
3
, 24 °C): δ =
m; HC4a,5a), 1.24–1.11 (m; HC4a,5a and HC4s,5s) ppm. 13C NMR 2.33–2.15 (m, 2 H), 2.01–1.62 (m, 14 H) ppm.
13
C
NMR
(
Eur. J. Inorg. Chem. 2008, 384–396
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
393

P. K l üfers, M. M. Reichvilser
FULL PAPER
Table 4. Crystallographic data for 10, 11, 12 and 13.
10
11
12
13
CCDC number
647114
647117
C H O Se
6 10 6
257.10
Empirical formula
C
5
H
8
O
3
Se
3
Se
4
Se
–
1
M
r
[gmol ]
195.07
Crystal size [mm]
0.15ϫ0.13ϫ0.02
monoclinic
0.25ϫ0.11ϫ0.02
monoclinic
0.20ϫ0.03ϫ0.01
monoclinic
0.14ϫ0.08ϫ0.08
orthorhombic
P2 2 2
1 1 1
6.0212(2)
10.8455(4)
13.1522(4)
90
Crystal system
Space group
a [Å]
b [Å]
c [Å]
P2
1
/c
P2
1
/c
P2
1
/c
4.72510(10)
24.3004(7)
5.9791(0)
90
21.1185(5)
6.5565(2)
12.7183(3)
90
4.37100(10)
11.7263(4)
11.4158(4)
90
α [°]
β [°]
111.3051(15)
90
639.61(3)
4
2.0258(1)
5.797
107.3810(10)
90
1680.61(8)
8
1.7637(1)
4.425
100.781(2)
90
574.80(3)
4
2.2770(1)
6.465
90
90
858.88(5)
4
1.9880(1)
4.369
γ [°] 3
V [Å ]
Z
–3
Calcd. density [gcm ]
µ [mm ]
–1
Absorption correction
Transmission factor range
Reflections measured
multi-scan
0.596–0.891
10776
0.0488
0.0323
3.35–27.51
1263
0.0183, 0.8930
–
1456
multi-scan
–
7610
0.0418
0.0427
3.20–27.51
3222
0.0707, 0.0685
–
multi-scan
–
2561
0.0176
0.0244
3.47–27.48
1181
0.0246, 0.3168
–
multi-scan
0.538–0.705
9216
0.0344
0.0377
3.62–27.49
1815
0.0109, 0.2880
0.031(10)
1913
R
int
Meanσ(I)/I
θ range
Observed reflections
x, y (weighting scheme)
Flack parameter
Reflections in refinement
Parameters
3861
201
1317
80
83
132
Restraints
0
0
0
0
R(Fobs
)
0.0302
0.0638
1.125
0.0422
0.1129
1.035
0.0212
0.0532
1.070
0.0231
0.0481
1.077
2
R (F )
w
S
Shift/errormax
0.001
0.467
–0.729
0.001
0.640
–0.687
0.001
0.440
–0.476
0.001
0.373
–0.385
–
–3
Max. e density [eÅ ]
–
–3
Min. e density [eÅ ]
1
3
(
2
9
67.9 MHz, CDCl
3
, 26 °C): δ = 100.8 (C
1
), 36.2/35.7 (C2,5), 24.2/
C NMR (67.9 MHz, CDCl
3
, 26 °C): δ = 59.1 (C1,3), 28.7
+
4.0 (C3,4) ppm. IR: ν˜ = 2953, 2871, 1448, 1430, 1173, 967, 938, (C
2
) ppm. MS (DCI , isobutane) m/z calcd. for C
3
H
7
O
3
Se [M +
–1
+
+
03, 866, 825, 656 cm . MS (DCI , isobutane) m/z calcd. for
1
H] 171.0; found 171.1 with a characteristic Se pattern.
+
C
10
H
17
O
3
Se [M + H] 265.0; found 265.1 with a characteristic Se
pattern. C10 Se (263.19): calcd. C 45.63, H 6.13; found C
5.92, H 6.11.
1
(
DmpdH–2)SeO (9): Prepared from 2,2-dimethylpropane-1,3-diol
16 3
H O
(
2.08 g, 20.0 mmol) and selenium dioxide (2.22 g, 20.0 mmol) in cy-
4
clohexane according to the general procedure. Pure 9 (3.51 g,
(
(
BhxdH–2)SeO (7): Prepared from 1,1Ј-bicyclohexyl-1,1Ј-diol
1.98 g, 10.0 mmol) and selenium dioxide (1.11 g, 10.0 mmol) in cy-
17.8 mmol, 89%) was immediately obtained as a colourless crystal-
line solid. M.p. 86.4–87.1 °C. Se NMR (76.2 MHz, CDCl ,
3
7
7
1
clohexane according to the general procedure. Pure 7 (2.68 g,
.20 mmol, 92%) was immediately obtained as a colourless crystal-
25 °C): δ = 1285 ppm. H NMR (400 MHz, CDCl
3
, 23 °C): δ =
4.72 (d, JH,H = 12 Hz, 2 H; HC1,3), 3.38 (d, JH,H = 12 Hz, 2 H;
HC1,3), 1.28 (s, 3 H, H C), 0.78 (s, 3 H, H
C) ppm. 13C NMR
(101 MHz, CDCl , 25 °C): δ = 68.3 (C1,3), 33.0 (C ), 22.6/21.9
(C4,5) ppm. IR: ν˜ = 2977, 2965, 2876, 1474, 1457, 1396, 1371, 1362,
2
2
9
77
line solid. M.p. 110.7–111.4 °C. Se NMR (76.2 MHz, CDCl
3
,
3
3
1
2
2
1
(
2
8
5 °C): δ = 1409 ppm. H NMR (400 MHz, CDCl
3
, 22 °C): δ =
3
2
.25–2.15 (m, 2 H), 1.84–1.63 (m, 12 H), 1.40–1.25 (m, 4 H), 1.22–
1
3
–1
+
.07 (m, 2 H) ppm. C NMR (101 MHz, CDCl
), 32.4/32.2 (C2,6), 25.4 (C ), 22.1/21.9 (C3,5) ppm. IR: ν˜ = 2923,
846, 1450, 1252, 1147, 1126, 937, 932, 918, 908, 898, 854, 834,
3
, 24 °C): δ = 92.6
1310, 1033, 970, 899, 776 cm . MS (DCI , isobutane) m/z calcd.
for C
Se [M + H]+ 199.0; found 199.1 with a characteristic
Se pattern. C Se (197.09): calcd. C 30.47, H 5.11; found C
30.54, H 5.17.
C
1
4
5 11 3
H O
1
5 10 3
H O
–1
+
09, 732, 696, 646 cm . MS (DCI , isobutane) m/z calcd. for
+
C
12
H
21
O
3
Se [M + H] 293.1; found 293.1 with a characteristic Se
pattern. C12 Se (291.25): calcd. C 49.49, H 6.92; found C
9.50, H 7.03.
1
(
BhmrH–2)SeO (10): Prepared from 1,1-bis(hydroxymethyl)cyclo-
propane (1.53 g, 15.0 mmol) and selenium dioxide (1.66 g,
5.0 mmol) in cyclohexane according to the general procedure.
Pure 10 (2.82 g, 14.5 mmol, 96%) was immediately obtained as a
20 3
H O
4
1
(
2
1,3-PrpdH–2)SeO (8): Prepared from propane-1,3-diol (1.52 g,
0.0 mmol) and selenium dioxide (2.22 g, 20.0 mmol) in cyclohex-
ane according to the general procedure. Pure 8 (3.06 g, 18.1 mmol,
7
7
colourless crystalline solid. M.p. 97–99 °C. Se NMR (51.5 MHz,
1
CDCl
δ = 5.29 (d, JH,H = 12 Hz, 2 H; HC1,3), 2.93 (d, JH,H = 12 Hz,
2 H; HC1,3), 0.78–0.71 (m, 2 H, HC ), 0.38–0.31 (m, 2 H,
, 25 °C): δ = 66.5 (C1,3),
), 12.2/7.6 (C4,5) ppm. IR: ν˜ = 3003, 2952, 2871, 1453, 1429,
3 3
, 25 °C): δ = 1295 ppm. H NMR (400 MHz, CDCl , 23 °C):
77
2
2
9
(
1%) was immediately obtained as a colourless powder. Se NMR
51.5 MHz, CDCl
, 26 °C): δ = 1301 ppm. 1H NMR (270 MHz,
, 24 °C): δ = 5.14–5.02 (m, 2 H, HC1,3), 3.93–3.84 (m, 2 H, HC
), 1.60–1.50 (m, 1 H, HC ) ppm. 19.8 (C
2
3
4
1
3
CDCl
3
5 3
) ppm. C NMR (101 MHz, CDCl
HC1,3), 2.62–2.43 (m, 1 H, HC
2
2
394
www.eurjic.org
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2008, 384–396

Structures and Reactions of Selenium(IV) Diolates
–
1
+
1
381, 1330, 1049, 1028, 977, 947, 929, 911, 769 cm . MS (DCI , (C2a), 63.6 (C2s), 61.4 (C5s), 58.4 (C5a), 55.1 (C6s), 54.8 (C6a) ppm.
+
isobutane) m/z calcd. for C
with a characteristic Se
3
5
H
9
O
3
Se [M + H] 197.0; found 197.1
pattern. C Se (195.08): calcd. C
0.78, H 4.13; found C 30.61, H 4.05.
IR: ν˜ = 3475, 2918, 1733, 1419, 1355, 13251196, 1135, 1084, 1058,
–
1
+
1
5
H
8
O
3
1025, 998, 960, 917, 860, 835, 787, 741, 669, 619 cm . MS (DCI ,
isobutane) m/z calcd. for C
Se [M + H]+ 259.0; found 259.0
with a characteristic Se pattern. C Se (257.10): calcd. C
8.03, H 3.92; found C 28.06, H 3.81.
6 11 6
H O
1
6 10 6
H O
(
BhmtH–2)SeO (11): Prepared from 1,1-bis(hydroxymethyl)cyclo-
pentane (1.32 g, 10.1 mmol) and selenium dioxide (1.13 g,
0.1 mmol) in cyclohexane according to the general procedure.
Pure 11 (2.07 g, 9.28 mmol, 92%) was immediately obtained as a
2
1
(Me-α-D-Manp2,3H–2)SeO (15): Prepared from methyl α--manno-
pyranoside (1.94 g, 10.0 mmol) and selenium dioxide (1.11 g,
10.0 mmol) in dioxane according to the general procedure. Com-
77
colourless crystalline solid. M.p. 56.2–57.2 °C.
Se NMR
1
(76.2 MHz, CDCl
3
, 25 °C): δ = 1289 ppm. H NMR (400 MHz,
, 23 °C): δ = 4.82 (d, J(H,H) = 12 Hz, 2 H; HC1,3), 3.45 (d, powder. The solvent could not be removed completely. Se NMR
pound 15, a mixture of two isomers, was obtained as a colourless
2
77
CDCl
3
2
J
H,H = 12 Hz, 2 H; HC1,3), 1.98–1.93 (m, 2 H), 1.74–1.65 (m, 2 H),
.65–1.56 (m, 2 H), 1.19–1.13 (m, 2 H) ppm. 13C NMR (101 MHz,
CDCl , 25 °C): δ = 67.0 (C1,3), 44.7 (C ), 33.25/33.22 (C4,7), 25.2/
4.5 (C5,6) ppm. MS (DCI , isobutane) m/z calcd. for C
Se 68.3 (C4a), 68.1 (C4s), 60.6 (C6s), 60.2 (C6a), 54.3 (C7a), 54.1
M + H]+ 225.0; found 225.1 with a characteristic Se
Se (223.13): calcd. C 37.68, H 5.42; found C 37.90, H 5.46.
(76.2 MHz, [D
6
]DMSO, 24 °C): δ = 1450 (syn), 1426 (anti) ppm.
C NMR (101 MHz, [D ]DMSO, 24 °C): δ = 97.7 (C1s), 97.4 (C1a),
83.1 (C3a), 82.5 (C3s), 80.9 (C2s), 77.9 (C2a), 72.6 (C5s), 71.8 (C5a),
13
1
6
3
2
+
2
[
C
7 13 3
H O
+
7 13 7
(C7s) ppm. MS (DCI , isobutane) m/z calcd. for C H O Se [M +
1
pattern.
+
H
12
O
3
H] 289.0; found 289.0 with a characteristic Se
1
pattern.
-Xylp3,4H–2)SeO
16b): Prepared from methyl β--xylopyranoside (1.64 g,
0.0 mmol) and selenium dioxide (1.11 g, 10.0 mmol) in dioxane
7
(
(
1
Me-β-D-Xylp2,3H–2)SeO (16a) and (Me-β-D
(
2
AnErytH–2)SeO (12): Prepared from 1,4-anhydroerythritol (2.08 g,
0.0 mmol) and selenium dioxide (2.22 g, 20.0 mmol) in cyclohex-
ane according to the general procedure. Pure 12 (3.71 g, 18.8 mmol,
according to the general procedure. A mixture of four isomers 16a
(syn/anti) and 16b (syn/anti), was obtained as a colourless powder.
9
4%), containing only one isomer, was immediately obtained as a
77
colourless crystalline solid. M.p. 162.2–163.0 °C.
Se NMR
7
7
, 24 °C): δ = 1492 ppm. 1H NMR (400 MHz,
76.2 MHz, CDCl
3
The solvent could not be removed completely.
Se NMR
(
(
76.2 MHz, [D ]DMSO, 24 °C): δ = 1447 (syn), 1446 (syn), 1432
6
3
CDCl , 23 °C): δ = 5.58–5.53 (m, 2 H, HC2,3), 4.12–4.07 (m, 2 H,
1
3
HC1,4), 3.76–3.69 (m, 2 H, HC1,4) ppm. 13C NMR (101 MHz,
(anti), 1431 (anti) ppm. C NMR (101 MHz, [D ]DMSO, 24 °C):
6
δ = 105.5, 105.3, 103.1, 102.6, 86.7, 85.9, 83.8, 82.8, 81.0, 78.3,
CDCl
1
6
[
C
3
, 24 °C): δ = 87.2 (C2,3), 73.7 (C1,4) ppm. IR: ν˜ = 2880, 1463,
321, 1289, 1104, 1079, 1047, 1011, 982, 919, 854, 831, 814, 734,
7
7.9, 75.0, 73.5, 72.7, 69.9, 69.0, 66.8, 66.6, 63.5, 63.3, 56.8, 56.0,
+
–1
+
7 13 7
55.8, 54.9 ppm. MS (DCI , isobutane) m/z calcd. for C H O Se
50, 622, 607 cm . MS (DCI , isobutane) m/z calcd. for C
4
H
7
O
4
Se
pattern.
4 6 4
H O Se (197.05): calcd. C 24.38, H 3.07; found C 24.19, H 2.92.
[M + H]+ 259.0; found 259.0 with a characteristic Se pattern.
M + H]+ 199.0; found 199.1 with a characteristic Se
1
1
(
Me-β-
D
-Ribf2,3H–2)SeO (13): Prepared from methyl β--ribofur- Acknowledgments
anoside (0.850 g, 5.18 mmol) and selenium dioxide (0.575 g,
.18 mmol) in dioxane according to the general procedure. Pure 13
1.15 g, 4.47 mmol, 86%), a mixture of two isomers, was immedi-
5
(
The crystal structure of 12 was solved using a data set obtained on
a crystal that had been prepared accidentally by Max Pfister and
Richard Betz. We acknowledge their generous contribution.
7
7
ately obtained as a colourless powder. Se NMR (76.2 MHz,
CDCl
1
3
, 24 °C): δ = 1492 (syn), 1481 (anti) ppm. H NMR
(
400 MHz, CDCl , 22 °C): δ = 5.57 (ddd, JH,H = 5.8, JH,H = 1.4,
3
[
1] J. W. Wyeth, R. E. Pounder, A. E. Duggan, C. A. O’Morain,
H. D. Schaufelberger, E. H. De Koster, E. A. J. Rauws, K. D.
Bardhan, J. Gilvarry, M. J. M. Buckley, P. A. Gummett,
R. P. H. Logan, Aliment. Pharmacol. Ther. 1996, 10, 623–630.
2] K. Benner, P. Klüfers, Carbohydr. Res. 2000, 327, 287–292.
J
0
6
H,H = 0.6 Hz; HC3a), 5.34 (ddd, JH,H = 6.3, JH,H = 1.7, JH,H
.6 Hz; HC3s), 5.32–5.29 (m; HC2a and HC1s), 5.16 (ddd, JH,H
=
=
.3, JH,H = 1.1, JH,H = 0.6 Hz; HC2s), 5.02 (s; HC1a), 4.72–4.69 (m;
[
HC4s), 4.47–4.44 (m; HC4a), 3.79–3.65 (m; HC5a and HC5s), 3.48 (s;
HC6s), 3.46 (s; HC6a) ppm. 1 C NMR (101 MHz, CDCl
3
[3] P. Klüfers, O. Labisch, Z. Anorg. Allg. Chem. 2003, 629, 1441–
445.
4] J. Burger, C. Gack, P. Klüfers, Angew. Chem. 1995, 107, 2950–
3
, 24 °C): δ
1
=
109.8 (C1s), 109.3 (C1a), 93.4 (C2s), 91.0 (C2a), 90.0 (C3s), 88.3
4s), 87.9 (C3a), 87.7 (C4a), 63.5 (C5a), 63.4 (C5s), 56.1 (C6s), 55.9
[
(C
2
951; Angew. Chem. Int. Ed. Engl. 1995, 34, 2647–2649.
(C
6a) ppm. IR: ν˜ = 3384, 2941, 1191, 1098, 1068, 1035, 1010, 986,
[
[
5] R. Betz, P. Klüfers, unpublished results.
–
1
+
9
25, 832, 807, 775, 678, 621 cm . MS (DCI , isobutane) m/z calcd.
6] K. Benner, P. Klüfers, J. Schuhmacher, Z. Anorg. Allg. Chem.
+
for C
Se
2
6
H
11
O
6
Se [M + H] 259.0; found 259.0 with a characteristic
Se (257.10): calcd. C 28.03, H 3.92; found C
1999, 625, 541–543.
1
pattern. C
6
H
10
O
6
[7] K. Benner, P. Klüfers, M. Vogt, Angew. Chem. 2003, 115, 1088–
1093; Angew. Chem. Int. Ed. 2003, 42, 1058–1062.
[
8.43, H 3.93.
8] P. Klüfers, F. Kopp, M. Vogt, Chem. Eur. J. 2004, 10, 4538–
545.
(
Me-β- -Ribp3,4H–2)SeO (14): Prepared from methyl β--ribopyr-
anoside (0.821 g, 5.00 mmol) and selenium dioxide (0.555 g,
.00 mmol) in dioxane according to the general procedure. Pure 14
1.16 g, 4.51 mmol, 90%), a mixture of two isomers, was immedi-
D
4
[
9] X. Kästele, P. Klüfers, F. Kopp, J. Schuhmacher, M. Vogt,
Chem. Eur. J. 2005, 11, 6326–6346.
5
(
[10] P. Klüfers, C. Vogler, Z. Anorg. Allg. Chem. 2007, 633, 908–
912.
[11] P. Klüfers, P. Mayer, Acta Crystallogr., Sect. C: Cryst. Struct.
Commun. 1998, 54, 583–586.
[
77
6
ately obtained as a colourless powder. Se NMR (76.2 MHz, [D ]
1
DMSO, 24 °C): δ = 1459 (anti), 1454 (syn) ppm. H NMR
400 MHz, [D ]DMSO, 22 °C): δ = 5.71 (s, broad; HO), 5.49 (s,
(
6
12] C. T. G. Knight, S. D. Kinrade, A primer on the aqueous chemis-
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