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A 13C-n.m.r. study of the tungstate and molybdate complexes of perseitol, galactitol, and d -mannitol
279
Carbohydrate Research, 211 (1991) 279~~286 Elsevier Science Publishers B.V., Amsterdam
A 13C-n.m.r. study of the tungstate and molybdate complexes of perseitol, galactitol, and D-mannitol* Stella Chapellet Lahoratoire
de R.M.N.
de I’UniversitG de Rouen,
76134 Mont-Saint-Aignan
and Jean-Francois U.R.A.
U.R.A.
464 du C.N.R.S.,
Faculth des Sciences,
B P. 118,
iFrance)
Verchtre
500 du C.N.R.S.,
UniwrsitP
de Rouen,
Fmul~k dcs Sciences,
i3.P. 118, 76/34 Mont-Saint-Aignan
(France) (Received
June
18th, 1990; accepted
for pubkation,
September
7th, 1990)
ABSTRACT
Perseitol stability
(D-gl~cero-D-galucto-heptitol)
higher than those of galactitol
magnitude
higher
complexes
had similar
than those for molybdate.
the galucto group D-Mannitol reversed
structures
in galactitol
and perseitol
formed
forms
and D-mannitol,
dinuclear
The ‘?C-n.m.r.
that involved and perseitol,
complexes
data showed
four vicinal hydroxyl complexes
that
have
a
are three orders of and molybdate
The sites of chelation
HO-3.45
that involved
tungstate
constants
that the tungstate
groups.
and the arahino group
pairs of isomeric
with
and all ofthe formation
and HO-6
involved
in D-mannitol.
the same site of chelatton
but in
orientations.
INTROI>UCTION
Alditols are well-known complexing agents for molybdate MOO,*- and tungstate WO,‘~ ions in aqueous acidic solution. Dinuclear anionic complexes are formed as indicated by a series of polarimetric and potentiometric studies’~“. The crystal structures of D-mannitol”.“’ and erythritol” molybdate complexes showed that the chelation involved four vicinal hydroxyl groups. ‘3C-N.m.r. studies demonstrated that themolybdate complexes of most polyols retained this structure in solution, and attempts were made to classify different types of tungstate’ and molybdate”~” complexes. y5Mo-N.m.r. spectroscopy revealed two non-equivalent MO atoms I4 in complexes of aldoses of the I~xoPmannn series, which chelated molybdate as tetradentate donors. Tungstate complexes have been used for the chromatographic separation of carbohydrates”, and alditols are useful complexing agents in the acidimetric titration of tungstate”‘. The thermodynamic data showed that the most stable complex was formed with perseitol (D-glycero-D-ga/acto-heptitol). We now report on the stabilities and structures of the molybdate and tungstate complexes of perseitol. Since two tetritol
* Communicated in part at the First Mediterranean 21-23, 1990. +Author for correspondence. 0008-6215/91/$03.50
@ 1991 - Elsevier
Conference
Science Publishers
on Carbohydrates,
B.V.
Avignon,
France,
May
280
S. < fihl'l~1.l.l..J.-f-. VI
K('fWKI
TUNGSTATE
TABLE
AND MOLYBDATE
COMPLEXES
281
II
100.62-MHz “C-n.m.r. complexes of galactitol
chemical
shifts (6 in p.p.m.) and ‘J,.,H values (Hz) for the tungstate
C-l
” ‘J,,u 141 Hz for C-I/6:
TABLE
OF ALDITOLS
c-2
c-3
C-4
C-5
and molybdate
C-6
65.5
71.5
72.1
72.1
71.5
65.5
65.3 143 -0.2
79.0 147 7.5
91.4 150 19.3
82.9 150 10.8
82.4 141 10.9
64.5 142 - 1.0
64.7 143 -0.X
19.4 144 7.9
91.8 149 19.7
83.7 I47 Il.6
83.3 146 11.8
65.5 143 0.0
6 assigned
from the literature”.
Accuracy:
J kO.1 p.p,m.;
J *I
Hz. ’ Ref. 13.
III
100.62-MHz “C-n.m.r. chemical complexes of u-mannitol
shifts (6 in p.p.m.)
C-I
and ‘J(.H values (Hz) for the tungstate
c-2
c-3
c-4
c-5
and molybdate
C-6
65.8
74.2
71.6
71.6
74.2
65.3 143 -0.5
72.9 143 - 1.3
81.9 147 10.3
82.7 150 Il.1
92.5 150 18.3
71.0 145 5.2
65.1 143 -0.7
73.7 143 -0.5
79.1 144 7.5
91.6 150 20.0
82.7 150 8.5
73.1 147 7.3
65.4 142
73.1 142
83.3 145
83.8 149
93.1 148
‘71.7 145
-0.4
-0.9
11.7
12.2
18.9
5.9
65.9 142 0.1
74.1 142 -0.1
80.3 143 x.7
92.3 148 20.7
83.8 149 9.6
‘74.1 1,45 8.3
” ‘JCH 141 Hz for C-1:6; b assigned
from the literature”.
Accuracy:
6 kO.1 p.p.m.;
65.8
J k 1 Hz. h Ref. 13.
complexes (M, and MJ that involved the arc&no group HO-3,4,5 and HO-6. The deshielding pattern characteristic of the galactitol species (i.e., 7-2tSlO-10 p.p.m.) was also observed for the D-mannitol complexes. However, for a given pair of complexes, these patterns were reversed, which suggested that the isomerism was due to the asymmetry of the chelating site, in which C-3,6 bore different substituents, in contrast to
hi
3
61.1 133 0 I
TUNGSTATE
AND MOLYBDATE
COMPLEXES
For the pair of molybdate matched
those reported”,
had been assigned and HO-3,4,5,6 unlikely, molybdate
the assignments
from ‘H- and ‘%-n.m.r.
since it was shown
Unambiguous
assignments
pair of perseitol
that
complexes
our spectra
The complexing
data as HO-2,3,4,5 t,-mannitol
The carbon-chain assignments
for P?. No evidence
closely
sites of perseitol
(the galucto group) in P,
did not complex
for the Pz molybdate
the proposed
assignment
differed.
IV), although
but with the galucto-like
experiments.
data. However,
above tentative
(Table
in Pz (see Fig. 1). The second assignment
above
by its munno group,
clear 2D-‘H-n.m.r. literature
complexes
(the manno group)
283
OF ALDITOLS
appeared
tungstate
or
group HO-3,4,5,6.
complex were made by homonusequence
was in agreement
were reversed
was obtained
differed from those formed
in order to verify the
to indicate
by alditols
with
that the P,-P,
that possess related
complexing sites such as D-arabinitol, D-mannitol, and D-glucitol”. Using an excess of molybdate, the 95Mo-n.m.r. spectra of perseitol-molybdateHCI mixtures contained a sharp signal for free molybdate at 6 -0 and a new broad
CH,OH
galacto
CH,OH Perseitol
Fig. 1. Schematic representation of the chelation of the dimolybdate anion by four vicinal hydroxyl groups of an alditol molecule; R and R’ are CH,OH in galactitol, H and CHOH-CH20H in u-mannitol, and CH20H and CWOH-CH20H in perseitol. When R + R’, a pair of isomers is formed. The dimolybdate structure is that characterised in the complexes of wmannitol’.‘” and erythritol”.
2x3
\.
(
tlAI’l~1.I.l
I.-f.
\.I K(~FII:KI:
TUNGSTATE
should
AND MOLYBDATE
COMPLEXES
285
OF ALDITOLS
have been much higher if complex
P? (40% of total) had involved
group. These results accord with the finding that molybdate goups of D-mannitol
and perseitol.
Determination quantitative
of the formation
support
molybdate-catalysed active
molybdate
Published
constants
for the interpretation epimerisation
species
of the molybdate
of recent results”
of aldoses.
by complexation,
It is believed thereby
data on the relative yields of the reaction
h, 90’) indicated
the manno
is not chelated by the manno
the order of stability
to be perseitol
that alditols
reducing
D-glucose
complexes
provides
on the inhibition
of the
scavenge
the
the rate of reaction.
-+ D-mannose
> galactitol
(pH 3.5, 3
> D-mannitol
>
D-arabinitol > ribitol, in excellent agreement with the results in Table I and earlier results for D-arabinitol and ribitol”, and confirm that the dinuclear molybdate complexes are the species responsible for the reported decrease in the rate of epimerisation. EXPERIMENTAL
All chemicals were of analytical grade and perseitol supplied. Water was de-ionised in a Millipore apparatus.
(Aldrich)
was used
as
Formation constants were determined by potentiometry’4x’6, based on the determination of the half-equivalence pH, ,2values in acidimetric (HCl) titrations of disodium molybdate
or tungstate
solutions
of known
concentration
that
contained
various
amounts of alditol. Measurements were made at constant ionic strength (KCl, 0.1~). All ID- and 2D-n.m.r. spectra were recorded with a Bruker AM 400 spectrometer equipped with a 5-mm multinuclear probe. Solutions contained alditol(0.5 mmol) and disodium molybdate or tungstate dihydrate (1.5 mmol) in DzO (0.5 cm”). Cont. HCl (0.75 mmol) was added last, in order to avoid the precipitation of tungsten trioxide. The ‘5Mo-n.m.r.
measurements
were made as described’3,‘4.
For the “C-n.m.r.
experiments, the proton-coupled and -decoupled spectra were obtained with n.0.e. The chemical shifts were determined by the substitution method’“, using the trimethylsilylphosphate reference signal in DzO. ZD-Heteronuclear experiments were performed*’ with polarisation transfer from ‘H to 13C, the number of experiments being 64 x 1k. Initial assignments of ‘H spectra of mixtures of complexes required 2D-homonuclear experiments
(COSY-45)22,‘3.
REFERENCES I 2 3 4 5 6 7 8 9 IO
I1
N. K. Richtmyer and C. S. Hudson, J. Am. Chum. SW.. 73 (1951) 2249 -2250. E. J. Bourne, D. H. Hutson, and H. Weigel, J. Chem. Sot.. (1961) 35-38. H. J. F. Angus and H. Weigel, J. Chem. Sot., (1964) 3994-4000. H. J. F. Angus, E. J. Bourne, and H. Weigel, d. Chem. SW., (1965) 21 -26. W. Voelter, E. Bayer, R. Records. E. Bunnenberg. and C. Djerassi, Chem. Bet-., 102 (1969) 1005-1019. L. Pettersson, Acta Chem. &and., 26 (1972) 4067-4083. M. Mikesova and M. Bartusek. Collect. Czech. Chem. Commun., 43 (1978) 1867-1877. E. Llopis, J. A. Ramirez, and A. Cervilla, Polyhedron, 5 (1986) 2069-2074. J. E. Godfrey and J. M. Waters, Cryst. Strut. Commun., 4 (1975) S-8. B. Hedman, Acta Cr~sfallogr., Sect. E, 33 (1977) 3077-3083. L. Ma, S. Liu, and J. Zubieta. Polyhedron, 8 (1989) 1571-1573.
Carbohydrate Research, 211 (1991) 279~~286 Elsevier Science Publishers B.V., Amsterdam
A 13C-n.m.r. study of the tungstate and molybdate complexes of perseitol, galactitol, and D-mannitol* Stella Chapellet Lahoratoire
de R.M.N.
de I’UniversitG de Rouen,
76134 Mont-Saint-Aignan
and Jean-Francois U.R.A.
U.R.A.
464 du C.N.R.S.,
Faculth des Sciences,
B P. 118,
iFrance)
Verchtre
500 du C.N.R.S.,
UniwrsitP
de Rouen,
Fmul~k dcs Sciences,
i3.P. 118, 76/34 Mont-Saint-Aignan
(France) (Received
June
18th, 1990; accepted
for pubkation,
September
7th, 1990)
ABSTRACT
Perseitol stability
(D-gl~cero-D-galucto-heptitol)
higher than those of galactitol
magnitude
higher
complexes
had similar
than those for molybdate.
the galucto group D-Mannitol reversed
structures
in galactitol
and perseitol
formed
forms
and D-mannitol,
dinuclear
The ‘?C-n.m.r.
that involved and perseitol,
complexes
data showed
four vicinal hydroxyl complexes
that
have
a
are three orders of and molybdate
The sites of chelation
HO-3.45
that involved
tungstate
constants
that the tungstate
groups.
and the arahino group
pairs of isomeric
with
and all ofthe formation
and HO-6
involved
in D-mannitol.
the same site of chelatton
but in
orientations.
INTROI>UCTION
Alditols are well-known complexing agents for molybdate MOO,*- and tungstate WO,‘~ ions in aqueous acidic solution. Dinuclear anionic complexes are formed as indicated by a series of polarimetric and potentiometric studies’~“. The crystal structures of D-mannitol”.“’ and erythritol” molybdate complexes showed that the chelation involved four vicinal hydroxyl groups. ‘3C-N.m.r. studies demonstrated that themolybdate complexes of most polyols retained this structure in solution, and attempts were made to classify different types of tungstate’ and molybdate”~” complexes. y5Mo-N.m.r. spectroscopy revealed two non-equivalent MO atoms I4 in complexes of aldoses of the I~xoPmannn series, which chelated molybdate as tetradentate donors. Tungstate complexes have been used for the chromatographic separation of carbohydrates”, and alditols are useful complexing agents in the acidimetric titration of tungstate”‘. The thermodynamic data showed that the most stable complex was formed with perseitol (D-glycero-D-ga/acto-heptitol). We now report on the stabilities and structures of the molybdate and tungstate complexes of perseitol. Since two tetritol
* Communicated in part at the First Mediterranean 21-23, 1990. +Author for correspondence. 0008-6215/91/$03.50
@ 1991 - Elsevier
Conference
Science Publishers
on Carbohydrates,
B.V.
Avignon,
France,
May
280
S. < fihl'l~1.l.l..J.-f-. VI
K('fWKI
TUNGSTATE
TABLE
AND MOLYBDATE
COMPLEXES
281
II
100.62-MHz “C-n.m.r. complexes of galactitol
chemical
shifts (6 in p.p.m.) and ‘J,.,H values (Hz) for the tungstate
C-l
” ‘J,,u 141 Hz for C-I/6:
TABLE
OF ALDITOLS
c-2
c-3
C-4
C-5
and molybdate
C-6
65.5
71.5
72.1
72.1
71.5
65.5
65.3 143 -0.2
79.0 147 7.5
91.4 150 19.3
82.9 150 10.8
82.4 141 10.9
64.5 142 - 1.0
64.7 143 -0.X
19.4 144 7.9
91.8 149 19.7
83.7 I47 Il.6
83.3 146 11.8
65.5 143 0.0
6 assigned
from the literature”.
Accuracy:
J kO.1 p.p,m.;
J *I
Hz. ’ Ref. 13.
III
100.62-MHz “C-n.m.r. chemical complexes of u-mannitol
shifts (6 in p.p.m.)
C-I
and ‘J(.H values (Hz) for the tungstate
c-2
c-3
c-4
c-5
and molybdate
C-6
65.8
74.2
71.6
71.6
74.2
65.3 143 -0.5
72.9 143 - 1.3
81.9 147 10.3
82.7 150 Il.1
92.5 150 18.3
71.0 145 5.2
65.1 143 -0.7
73.7 143 -0.5
79.1 144 7.5
91.6 150 20.0
82.7 150 8.5
73.1 147 7.3
65.4 142
73.1 142
83.3 145
83.8 149
93.1 148
‘71.7 145
-0.4
-0.9
11.7
12.2
18.9
5.9
65.9 142 0.1
74.1 142 -0.1
80.3 143 x.7
92.3 148 20.7
83.8 149 9.6
‘74.1 1,45 8.3
” ‘JCH 141 Hz for C-1:6; b assigned
from the literature”.
Accuracy:
6 kO.1 p.p.m.;
65.8
J k 1 Hz. h Ref. 13.
complexes (M, and MJ that involved the arc&no group HO-3,4,5 and HO-6. The deshielding pattern characteristic of the galactitol species (i.e., 7-2tSlO-10 p.p.m.) was also observed for the D-mannitol complexes. However, for a given pair of complexes, these patterns were reversed, which suggested that the isomerism was due to the asymmetry of the chelating site, in which C-3,6 bore different substituents, in contrast to
hi
3
61.1 133 0 I
TUNGSTATE
AND MOLYBDATE
COMPLEXES
For the pair of molybdate matched
those reported”,
had been assigned and HO-3,4,5,6 unlikely, molybdate
the assignments
from ‘H- and ‘%-n.m.r.
since it was shown
Unambiguous
assignments
pair of perseitol
that
complexes
our spectra
The complexing
data as HO-2,3,4,5 t,-mannitol
The carbon-chain assignments
for P?. No evidence
closely
sites of perseitol
(the galucto group) in P,
did not complex
for the Pz molybdate
the proposed
assignment
differed.
IV), although
but with the galucto-like
experiments.
data. However,
above tentative
(Table
in Pz (see Fig. 1). The second assignment
above
by its munno group,
clear 2D-‘H-n.m.r. literature
complexes
(the manno group)
283
OF ALDITOLS
appeared
tungstate
or
group HO-3,4,5,6.
complex were made by homonusequence
was in agreement
were reversed
was obtained
differed from those formed
in order to verify the
to indicate
by alditols
with
that the P,-P,
that possess related
complexing sites such as D-arabinitol, D-mannitol, and D-glucitol”. Using an excess of molybdate, the 95Mo-n.m.r. spectra of perseitol-molybdateHCI mixtures contained a sharp signal for free molybdate at 6 -0 and a new broad
CH,OH
galacto
CH,OH Perseitol
Fig. 1. Schematic representation of the chelation of the dimolybdate anion by four vicinal hydroxyl groups of an alditol molecule; R and R’ are CH,OH in galactitol, H and CHOH-CH20H in u-mannitol, and CH20H and CWOH-CH20H in perseitol. When R + R’, a pair of isomers is formed. The dimolybdate structure is that characterised in the complexes of wmannitol’.‘” and erythritol”.
2x3
\.
(
tlAI’l~1.I.l
I.-f.
\.I K(~FII:KI:
TUNGSTATE
should
AND MOLYBDATE
COMPLEXES
285
OF ALDITOLS
have been much higher if complex
P? (40% of total) had involved
group. These results accord with the finding that molybdate goups of D-mannitol
and perseitol.
Determination quantitative
of the formation
support
molybdate-catalysed active
molybdate
Published
constants
for the interpretation epimerisation
species
of the molybdate
of recent results”
of aldoses.
by complexation,
It is believed thereby
data on the relative yields of the reaction
h, 90’) indicated
the manno
is not chelated by the manno
the order of stability
to be perseitol
that alditols
reducing
D-glucose
complexes
provides
on the inhibition
of the
scavenge
the
the rate of reaction.
-+ D-mannose
> galactitol
(pH 3.5, 3
> D-mannitol
>
D-arabinitol > ribitol, in excellent agreement with the results in Table I and earlier results for D-arabinitol and ribitol”, and confirm that the dinuclear molybdate complexes are the species responsible for the reported decrease in the rate of epimerisation. EXPERIMENTAL
All chemicals were of analytical grade and perseitol supplied. Water was de-ionised in a Millipore apparatus.
(Aldrich)
was used
as
Formation constants were determined by potentiometry’4x’6, based on the determination of the half-equivalence pH, ,2values in acidimetric (HCl) titrations of disodium molybdate
or tungstate
solutions
of known
concentration
that
contained
various
amounts of alditol. Measurements were made at constant ionic strength (KCl, 0.1~). All ID- and 2D-n.m.r. spectra were recorded with a Bruker AM 400 spectrometer equipped with a 5-mm multinuclear probe. Solutions contained alditol(0.5 mmol) and disodium molybdate or tungstate dihydrate (1.5 mmol) in DzO (0.5 cm”). Cont. HCl (0.75 mmol) was added last, in order to avoid the precipitation of tungsten trioxide. The ‘5Mo-n.m.r.
measurements
were made as described’3,‘4.
For the “C-n.m.r.
experiments, the proton-coupled and -decoupled spectra were obtained with n.0.e. The chemical shifts were determined by the substitution method’“, using the trimethylsilylphosphate reference signal in DzO. ZD-Heteronuclear experiments were performed*’ with polarisation transfer from ‘H to 13C, the number of experiments being 64 x 1k. Initial assignments of ‘H spectra of mixtures of complexes required 2D-homonuclear experiments
(COSY-45)22,‘3.
REFERENCES I 2 3 4 5 6 7 8 9 IO
I1
N. K. Richtmyer and C. S. Hudson, J. Am. Chum. SW.. 73 (1951) 2249 -2250. E. J. Bourne, D. H. Hutson, and H. Weigel, J. Chem. Sot.. (1961) 35-38. H. J. F. Angus and H. Weigel, J. Chem. Sot., (1964) 3994-4000. H. J. F. Angus, E. J. Bourne, and H. Weigel, d. Chem. SW., (1965) 21 -26. W. Voelter, E. Bayer, R. Records. E. Bunnenberg. and C. Djerassi, Chem. Bet-., 102 (1969) 1005-1019. L. Pettersson, Acta Chem. &and., 26 (1972) 4067-4083. M. Mikesova and M. Bartusek. Collect. Czech. Chem. Commun., 43 (1978) 1867-1877. E. Llopis, J. A. Ramirez, and A. Cervilla, Polyhedron, 5 (1986) 2069-2074. J. E. Godfrey and J. M. Waters, Cryst. Strut. Commun., 4 (1975) S-8. B. Hedman, Acta Cr~sfallogr., Sect. E, 33 (1977) 3077-3083. L. Ma, S. Liu, and J. Zubieta. Polyhedron, 8 (1989) 1571-1573.