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Infrared and paH correlation of proton transfer in and bridges in acetonitrile
369
Journalofbfokcu&rSt~~ture,143(1999)969-974 ElsevierSciencepUbli&era B.V.. Am&e&m - Priuted in The NetJmlmdr
INFRARED ($NHN,E 2.
AND pat4 CORRELATION )+ BRIDGES
IN
OF PROTON TRANSFER IN
(-NDHNC )+ AND
ACETONITRILE
PARLAK
Department of Economics Sopot ( Poland )
of
Production,
University
of
Gdansk,
ABSTRACT Hydrogen bond complexing (BHB)+ between N-bases and their cations has been examined by infrared spectroscopy and potentiIn the acetonitrile (AN) solution there have been studometry. ied hetsro-systems ( B + BlH+ ), where the differing bases, B, may N-methylpipsridine, norphollne, N-methylbe triethylamfne, imidazole, pyridine, 2- and %chloropyridine, quinoline and trimethyl-N-oxide with BiH* : trimethyl-N-oxideH+ and N-msthylinidazolsH* . Hoaoconplex ( Me3N0)2H+ has been distin uished. In the H-bridges cation the stretching band vs(NH+) and 9 -OH* 1are dependent directly on the paH and formation constant Kf of the colnponent bases. INTRODUCTION fn
the
rence
of
formula or -
earlier a wide
range
where
BHB: ,
N-oxide.
of
stable
B and
BIH+)
equilibrium
pass
from
(INCH*’
1,
(refs
3 -
bridges 7),
band
2700 gs(NH+)
ratio of
the
of
bonds
-
1900
or
(sNi.
at
cm-’
MeSNOH*/N-base
bands
absorption In this
in
in the
paper
0022.2360/36/$03.50
the
in
drop
2800
regibn there
one
l
*NE.
below
positive
the B)
two
broad
stretching
There
1600
described
-
ones
the
fol-
is
the
spectra techniques,
bands
in
the
vibration
An equimolar spectral
properties
no appearance
region -1 . GUI
0 1996 Elsevier SciencePublishers
other
The
intensity.
cm-’
N-bases BH*)
infrared
and
different
- 1600
are
or
observed.
general
- * HNS )’
1, 2,
indicated
bond -NOHt
hydrogen
sortion
3000
formed. are
the
occur-
t
(b) from
(refs
are
cm-’
to
present
recognized
potentiometry
ahen (J’NHN$ region
were
of
the
eame;dissioilar
= p$N(acceptor,
negative
- . Ng )’
cations
be the
(a) The( SNHN~)+
2 ) we reported
complex
B can 1 ofApKtN
(a ) and ( b ) is
Kf
_=NIH+ + N$ -
( refs
studies
I%hen values
pKtN (donor,
lowing
emf
and
investigations B.V.
of
increase
ab-
of of
infra-
370 red spectra
and emf measurements
ylimidazolsH+
perchlorates
The purpose
at 298K. evidence
trimethyl-N-oxideH*
with
of
our
free
study
eight
bases
was to get
(ZNHNis )+, (-NOHNE)+ bridges
in acetonitrile
a new independent
the sNH* end -OH* stretching
between
and N-meth-
frequency
and p,H and the
formation
for constants
Kf( BHBi)+ heterocomplexes. EXPERIMENTAL Acetonitrile
wes purified
Perchlorates pyridine
of
piperidine (Morph), butions
(refs
1,
model
drnm3 in 0.05
recorded
before
ths
perchlorate
contri-
spectrometer
in a CH3CN solution
to a precision
titrant
N-base
base was 0.001
end the procedure
and the
( refs
a Perkin-Elmer
taken
1,
of
E353 ( Metrohm Herisau
of
electrode
pcN(BH+)
( Me3NO) were
in earlier
0.5
qol
to 0.5
mol
mol dmw3 base.
Potentiometer
and the
forth
mm cell, for with complexes it refers
+ 0.5
Concentretion glass
was set
using
were
The emf were measured sion
( NMeIm1, morpholine
2).
were
The spectra
325.
drnB3 salt
as it
%chloro-
(Quinol ), N-methyl-
(TEA) and trimethyl-N-oxide
end purified
spectra
( ref. B ).
( 2-CIPy ),
( Py ), quinoline
N-methylimidarole
triethylamine
synthetized It
pyridine
( N-MePip),
dried
2-chloropyridine
N-bases:
( 3-ClPy ) ,
and vigorously
formation
1mV by using
) end glass
a Preci-
electrode.
or Me3N0 were 0.025 no1 drnm3.
of
The calibration
determining
constents,
mol dmo3
of
Kf ( BHBl )+,
of
acidity
were
as
2 ).
RESULTS AND DISCUSSION The types a ) system hydrogen
of
complexes
characteristic
bond
(-NO*H*ON-)+
of
intensity
absorption
is
absorption
band shows
that
Trimethyl-N-oxideH+
Me3NOH+ cations shows
complex
that
less
free
as well cm”
region
with
below
are
+ N-base
es
the
the
symmetric complete
and increase
1600 cm-’
(see Fig.1).
complexed.
of
N-bases
displaying
Protonatsd
(see Fig. 2A )
a strong,
With added
Me3NOH* ions
For
for
region
complexes.
a range
.
spectrum
observed
protons
following:
1:l
in the-3000
in the all
the $$ band -OH+ region around-3000 cm-1 .
centered
indicates
by the
Me3NOH+ + Me3N0 the of
b )
exemplified
+ Trimethyl-N-oxide
disappearance The gs
are
Trimethyl-N-oxideH+
N-bases
are
present.
broad the
band
spectra The changes
371
Fig. 1. Infrared spectra in acetonitrile, concentration 0.5 mol dm-3, layer thickness 0.1 mm;1 )MeSNOH+ClOa + Me3N0, 1:l; (--_)Me9NO;(.--.***-*)MeSNOHClOz.
372
in the absorption spectrum on adding strong N-bases to salt solution (lrl, C - 0.5 mol dm-3 )ths
Me3NOH+ClO;
stretching The
vibration band of the -OH* is almost no longer apparent. indicates
less basic N-bases 2- and 3-CIPy, Py andQuino1
main part free of Me3NOH+ ions is still present.
that the
Vie conclude
that the equilibrium: 2(Me
3
NOH?*,B)
=
(Me3N0)2H+ + (BH~)+
favours the lsft hand side when the difference in the pK:” the bases isApK,< No. 5+8,(see
of
0, as in Me3NOH+/B and N-MeIwH*/B , system
the table).
TABLE Acidity constants, pK,AN(BH+), formation constants, and hetsrocomplexes in acstonitrile at 29BK N-MeImHfe - B APK;"&
1ogKf
homo-
Me NOH+* ’ B 3 cc 8 APK~~ lWf l
logKf' Curve P
Curve P
1 2 3
TEA N-MePip
17.24 16.29
+2.94 +1.99
1.40; 1.84;
s S
+o l31 -0.64
4.11; 4.14;
Morph
16.09
+1.79
1.73; s
-0.84
4.02; L
4
N-MeIm
14.30
5 6
PY Quinol 3.ClPy ;,C',;Y 3
12.52 12.03 10.13 7.76 16.96
0.00 -1.78
3.87; 2.20;
-2.63 -4.41
3.10; 2.46;
L L
-2.27 -4.17 -6.54 -
1.94; L 2.101 L 1.50; L -
-4.90 -6.80 -9.17 0.00
2.30; 1.60; 1.42; 6.51:
L L L S
7 ;
L L
L L
AN BH*) = pKe [acceptor, BiH*) - pKy(donor, P Type of titration curve p,H - f(C B/C BiH+); linear{ L)# sigmoidal ( S). YRef. 2. s Calculated from K * [BHBl/(c, - [BHB;]} {CBIH+ - [BHB:]} for details see ref.1 and’2.
%PK$
c )
N-methylimidaroleH*
+ N-base
complexes.
,
The N-MeImH+ en-
ters into a wide range of complex hydrogen bonded cations, involving N-bases of both larger end smaller pKa AN( BH+) as well a8 self coaplexing. Fig.28 illustrates two possibilities. The 3, band in self associated (N-MeIn)2H+ displeys quite e pronounced doublet structurs with the maxima at ca 2000 and ca 2450 cm” 4, 6). In the presence of l:l, TEA, N-MePip, Morph, Py and Quinol the appearance of gs band markedly changes (see Fig. (refs
28 ), and shows
broad
doublet
bends.
The complexes
313 N-MeImH+/2-ClPy is
not
and
The
behaviour
occurance
account
in
an
strengths,
in a
of
pK,(
those
this
BH+)
and
with
the
of
be
explained
in
N-MeImH+
The
sigmoidal
curves
and
Morph
curves
B/N-MeImH+
a
of
break proton
homocomplexes The
N-MePip
The
l
for Morph
- 8,
the
intensity
directly p,H
a group
lf3
paH
+
the
is
very
W
B ==Z table
4
more
for
to
the
The
l
found.
constants
for
)2H*
B ( where than
is
Bz
2.
the
equilibrium
3.87.
TEA,
for
about
of
with
positive,
is
( NH*)and(-OH’)
gs
p,H
1:l
units
(N-MeIm
-
concentration
sensitive
2f3
-B )
-
N-MePip
).
- N-MeIm
logKf of
TEA, Table
extensive
bands
N-MeImH%
formation
and
constants,
the
is
the
activity
B/N-MeImH+,
BH? .
Me3NCH?
is
ebsorption with
for
) show
Table
0
bases: (see
units
5.51
formation of
of 0
units.
=
proton
( or
5
with
complex,
pKzN<
B
l
V&enapKtN
in
logKf
correlated
tons;
with
l
Me3N0
of
(see
the
A
aceto-
curve
paH
4+9
in
Me 3NOHt
heterocomplexss
],
stable
reaction,
logKfBMe3NO)2H+]=
or
N-MsImH+*
Z
given
interaction
change
very
No.
the
N-MeImH+
results
paH
base
in
titration
systems,
into
the
with
a the
N-MeIm,ApKzN> ca
titration a
changes
activity.
transfer
the
of
occur
a
proton
From
doublet
taken of
has
activity
)+ B S
than
decreasing
the
broad
been
hydrogen
small
terms
stronger
have
The
The
( or
Me3NOH+
formation
observed.
) and
can
a
Kf( BHBl)*
on It
Ms3NOH+/Ma3N0
case
has
constents,
behaviour.
NOH+ f (CB/CMe linear rs 9 ationship.
a
and
determination
trimethyl-N-oxide
ratio
is
complexes
formation
unusual
extreme
stabla
potentiometric
Protonated
rile.
Me3N0.H.0NMeg =
weak
complexes
accurate
CH CN exibit 3 break at 1:l
In
are
observed.
Potentiometric
nit
N-MeImH+/3-ClPy
are
solvated
BIH+‘=*
pro-
B =
l
B . * +HB. 1 The dependence
may
also
tion
of
curve
be the
B ).
3s 3
paH
degree stronger
of
hydrogen
linearly. the
band
shows
on the
( N-MeImH*/N-base,
paH The
the
Fig.
donor
( N-MeImH*/N-bases
N-bases with
of
used.
) of
However, (-NOH*.*
interaction
NS with
)’
the
curve property the the
bond
(‘jiNIH observed foraation
nonlinearity.
composition
$,(31BO A, of w
and the
l
l
of
the
) band
cm-’
as
system a
func-
Me3NOH+/N-base, lone
pair
NE )+ bond
dependence demonstrates Me3NBH+
is
is of
of increasing the a much
Involved
314
plotted as the function of p&J CBH+sCBm 0.001 mol dm I ; Systemsr
strongly in the delocalization of the lone pair of N-bases, parAN titularly when pKa of those protonated N-bases (TEA, N-MePip and Morph ) are ence
(see Table). When the diffsrto p tiN(Me3NOH+) between ge3NOH+ and TEAH+, N-MsPipH+, MorphI? is
close
npKa AN
small and equals +0.31, -0.64 and -0.84, respsctively, the intensity of the $,(OH*) is obssrved just as with the symmetrical hydrogen bond similar to the [Me3NO12H+ complex. fact that oxygen is more negativs than strongly delocalized in the -NOHf This work
was partly
supported
l
- N,l
nitrogen
Owing to the the
hydrogen
by Grant
from
proton
is
bridge. MR I-11.
Vie thank Professor Eltbista Winnicka and Miss Joanna Pawlak for their assistance in the preparation of this manuscript. REFERENCES 1 Z. Pawlak, A. wawrzyn6w, 3. Chem. 2
Sot., Faraday Trans I, 79 ( 1983 ) 1523-1531. z. Pswlak, G. Zundel, 3. Fritsch, Electrochimica Acta,
7
29 (1984 )391-395. Z. Pawlak, L.Sobczyk, Adv. Mol. Relaxation Processes, 5 (1973 )99-106. R.L. Dean, J.L. Wood, J. Mol. Structure, 26 (1975 ) 197-213, 215-235. B. Brzezinski, G. Zundel, 3. Cham. SOC.. Faraday Trans II, 72 ( 1976 ) 2127-2137. B. Brzezinski, M. Szafran, Roczniki Chsmii, 51 (1977 ) 1779.1782. H. Romanowski, L. Sobczyk, J. Phys. Chem., 79 (1975)
8
2535.~2541. +F. Costzse,
3 4 5 6
G.R.
Padaanabhan,
G.P.
Cunningham,
Talanta,
11 (1964)93-103. 9
3.F.
Coettee,
Progr.
Phys.
Org.
Chem.,
4 (1966)
45-92.
Journalofbfokcu&rSt~~ture,143(1999)969-974 ElsevierSciencepUbli&era B.V.. Am&e&m - Priuted in The NetJmlmdr
INFRARED ($NHN,E 2.
AND pat4 CORRELATION )+ BRIDGES
IN
OF PROTON TRANSFER IN
(-NDHNC )+ AND
ACETONITRILE
PARLAK
Department of Economics Sopot ( Poland )
of
Production,
University
of
Gdansk,
ABSTRACT Hydrogen bond complexing (BHB)+ between N-bases and their cations has been examined by infrared spectroscopy and potentiIn the acetonitrile (AN) solution there have been studometry. ied hetsro-systems ( B + BlH+ ), where the differing bases, B, may N-methylpipsridine, norphollne, N-methylbe triethylamfne, imidazole, pyridine, 2- and %chloropyridine, quinoline and trimethyl-N-oxide with BiH* : trimethyl-N-oxideH+ and N-msthylinidazolsH* . Hoaoconplex ( Me3N0)2H+ has been distin uished. In the H-bridges cation the stretching band vs(NH+) and 9 -OH* 1are dependent directly on the paH and formation constant Kf of the colnponent bases. INTRODUCTION fn
the
rence
of
formula or -
earlier a wide
range
where
BHB: ,
N-oxide.
of
stable
B and
BIH+)
equilibrium
pass
from
(INCH*’
1,
(refs
3 -
bridges 7),
band
2700 gs(NH+)
ratio of
the
of
bonds
-
1900
or
(sNi.
at
cm-’
MeSNOH*/N-base
bands
absorption In this
in
in the
paper
0022.2360/36/$03.50
the
in
drop
2800
regibn there
one
l
*NE.
below
positive
the B)
two
broad
stretching
There
1600
described
-
ones
the
fol-
is
the
spectra techniques,
bands
in
the
vibration
An equimolar spectral
properties
no appearance
region -1 . GUI
0 1996 Elsevier SciencePublishers
other
The
intensity.
cm-’
N-bases BH*)
infrared
and
different
- 1600
are
or
observed.
general
- * HNS )’
1, 2,
indicated
bond -NOHt
hydrogen
sortion
3000
formed. are
the
occur-
t
(b) from
(refs
are
cm-’
to
present
recognized
potentiometry
ahen (J’NHN$ region
were
of
the
eame;dissioilar
= p$N(acceptor,
negative
- . Ng )’
cations
be the
(a) The( SNHN~)+
2 ) we reported
complex
B can 1 ofApKtN
(a ) and ( b ) is
Kf
_=NIH+ + N$ -
( refs
studies
I%hen values
pKtN (donor,
lowing
emf
and
investigations B.V.
of
increase
ab-
of of
infra-
370 red spectra
and emf measurements
ylimidazolsH+
perchlorates
The purpose
at 298K. evidence
trimethyl-N-oxideH*
with
of
our
free
study
eight
bases
was to get
(ZNHNis )+, (-NOHNE)+ bridges
in acetonitrile
a new independent
the sNH* end -OH* stretching
between
and N-meth-
frequency
and p,H and the
formation
for constants
Kf( BHBi)+ heterocomplexes. EXPERIMENTAL Acetonitrile
wes purified
Perchlorates pyridine
of
piperidine (Morph), butions
(refs
1,
model
drnm3 in 0.05
recorded
before
ths
perchlorate
contri-
spectrometer
in a CH3CN solution
to a precision
titrant
N-base
base was 0.001
end the procedure
and the
( refs
a Perkin-Elmer
taken
1,
of
E353 ( Metrohm Herisau
of
electrode
pcN(BH+)
( Me3NO) were
in earlier
0.5
qol
to 0.5
mol
mol dmw3 base.
Potentiometer
and the
forth
mm cell, for with complexes it refers
+ 0.5
Concentretion glass
was set
using
were
The emf were measured sion
( NMeIm1, morpholine
2).
were
The spectra
325.
drnB3 salt
as it
%chloro-
(Quinol ), N-methyl-
(TEA) and trimethyl-N-oxide
end purified
spectra
( ref. B ).
( 2-CIPy ),
( Py ), quinoline
N-methylimidarole
triethylamine
synthetized It
pyridine
( N-MePip),
dried
2-chloropyridine
N-bases:
( 3-ClPy ) ,
and vigorously
formation
1mV by using
) end glass
a Preci-
electrode.
or Me3N0 were 0.025 no1 drnm3.
of
The calibration
determining
constents,
mol dmo3
of
Kf ( BHBl )+,
of
acidity
were
as
2 ).
RESULTS AND DISCUSSION The types a ) system hydrogen
of
complexes
characteristic
bond
(-NO*H*ON-)+
of
intensity
absorption
is
absorption
band shows
that
Trimethyl-N-oxideH+
Me3NOH+ cations shows
complex
that
less
free
as well cm”
region
with
below
are
+ N-base
es
the
the
symmetric complete
and increase
1600 cm-’
(see Fig.1).
complexed.
of
N-bases
displaying
Protonatsd
(see Fig. 2A )
a strong,
With added
Me3NOH* ions
For
for
region
complexes.
a range
.
spectrum
observed
protons
following:
1:l
in the-3000
in the all
the $$ band -OH+ region around-3000 cm-1 .
centered
indicates
by the
Me3NOH+ + Me3N0 the of
b )
exemplified
+ Trimethyl-N-oxide
disappearance The gs
are
Trimethyl-N-oxideH+
N-bases
are
present.
broad the
band
spectra The changes
371
Fig. 1. Infrared spectra in acetonitrile, concentration 0.5 mol dm-3, layer thickness 0.1 mm;1 )MeSNOH+ClOa + Me3N0, 1:l; (--_)Me9NO;(.--.***-*)MeSNOHClOz.
372
in the absorption spectrum on adding strong N-bases to salt solution (lrl, C - 0.5 mol dm-3 )ths
Me3NOH+ClO;
stretching The
vibration band of the -OH* is almost no longer apparent. indicates
less basic N-bases 2- and 3-CIPy, Py andQuino1
main part free of Me3NOH+ ions is still present.
that the
Vie conclude
that the equilibrium: 2(Me
3
NOH?*,B)
=
(Me3N0)2H+ + (BH~)+
favours the lsft hand side when the difference in the pK:” the bases isApK,< No. 5+8,(see
of
0, as in Me3NOH+/B and N-MeIwH*/B , system
the table).
TABLE Acidity constants, pK,AN(BH+), formation constants, and hetsrocomplexes in acstonitrile at 29BK N-MeImHfe - B APK;"&
1ogKf
homo-
Me NOH+* ’ B 3 cc 8 APK~~ lWf l
logKf' Curve P
Curve P
1 2 3
TEA N-MePip
17.24 16.29
+2.94 +1.99
1.40; 1.84;
s S
+o l31 -0.64
4.11; 4.14;
Morph
16.09
+1.79
1.73; s
-0.84
4.02; L
4
N-MeIm
14.30
5 6
PY Quinol 3.ClPy ;,C',;Y 3
12.52 12.03 10.13 7.76 16.96
0.00 -1.78
3.87; 2.20;
-2.63 -4.41
3.10; 2.46;
L L
-2.27 -4.17 -6.54 -
1.94; L 2.101 L 1.50; L -
-4.90 -6.80 -9.17 0.00
2.30; 1.60; 1.42; 6.51:
L L L S
7 ;
L L
L L
AN BH*) = pKe [acceptor, BiH*) - pKy(donor, P Type of titration curve p,H - f(C B/C BiH+); linear{ L)# sigmoidal ( S). YRef. 2. s Calculated from K * [BHBl/(c, - [BHB;]} {CBIH+ - [BHB:]} for details see ref.1 and’2.
%PK$
c )
N-methylimidaroleH*
+ N-base
complexes.
,
The N-MeImH+ en-
ters into a wide range of complex hydrogen bonded cations, involving N-bases of both larger end smaller pKa AN( BH+) as well a8 self coaplexing. Fig.28 illustrates two possibilities. The 3, band in self associated (N-MeIn)2H+ displeys quite e pronounced doublet structurs with the maxima at ca 2000 and ca 2450 cm” 4, 6). In the presence of l:l, TEA, N-MePip, Morph, Py and Quinol the appearance of gs band markedly changes (see Fig. (refs
28 ), and shows
broad
doublet
bends.
The complexes
313 N-MeImH+/2-ClPy is
not
and
The
behaviour
occurance
account
in
an
strengths,
in a
of
pK,(
those
this
BH+)
and
with
the
of
be
explained
in
N-MeImH+
The
sigmoidal
curves
and
Morph
curves
B/N-MeImH+
a
of
break proton
homocomplexes The
N-MePip
The
l
for Morph
- 8,
the
intensity
directly p,H
a group
lf3
paH
+
the
is
very
W
B ==Z table
4
more
for
to
the
The
l
found.
constants
for
)2H*
B ( where than
is
Bz
2.
the
equilibrium
3.87.
TEA,
for
about
of
with
positive,
is
( NH*)and(-OH’)
gs
p,H
1:l
units
(N-MeIm
-
concentration
sensitive
2f3
-B )
-
N-MePip
).
- N-MeIm
logKf of
TEA, Table
extensive
bands
N-MeImH%
formation
and
constants,
the
is
the
activity
B/N-MeImH+,
BH? .
Me3NCH?
is
ebsorption with
for
) show
Table
0
bases: (see
units
5.51
formation of
of 0
units.
=
proton
( or
5
with
complex,
pKzN<
B
l
V&enapKtN
in
logKf
correlated
tons;
with
l
Me3N0
of
(see
the
A
aceto-
curve
paH
4+9
in
Me 3NOHt
heterocomplexss
],
stable
reaction,
logKfBMe3NO)2H+]=
or
N-MsImH+*
Z
given
interaction
change
very
No.
the
N-MeImH+
results
paH
base
in
titration
systems,
into
the
with
a the
N-MeIm,ApKzN> ca
titration a
changes
activity.
transfer
the
of
occur
a
proton
From
doublet
taken of
has
activity
)+ B S
than
decreasing
the
broad
been
hydrogen
small
terms
stronger
have
The
The
( or
Me3NOH+
formation
observed.
) and
can
a
Kf( BHBl)*
on It
Ms3NOH+/Ma3N0
case
has
constents,
behaviour.
NOH+ f (CB/CMe linear rs 9 ationship.
a
and
determination
trimethyl-N-oxide
ratio
is
complexes
formation
unusual
extreme
stabla
potentiometric
Protonated
rile.
Me3N0.H.0NMeg =
weak
complexes
accurate
CH CN exibit 3 break at 1:l
In
are
observed.
Potentiometric
nit
N-MeImH+/3-ClPy
are
solvated
BIH+‘=*
pro-
B =
l
B . * +HB. 1 The dependence
may
also
tion
of
curve
be the
B ).
3s 3
paH
degree stronger
of
hydrogen
linearly. the
band
shows
on the
( N-MeImH*/N-base,
paH The
the
Fig.
donor
( N-MeImH*/N-bases
N-bases with
of
used.
) of
However, (-NOH*.*
interaction
NS with
)’
the
curve property the the
bond
(‘jiNIH observed foraation
nonlinearity.
composition
$,(31BO A, of w
and the
l
l
of
the
) band
cm-’
as
system a
func-
Me3NOH+/N-base, lone
pair
NE )+ bond
dependence demonstrates Me3NBH+
is
is of
of increasing the a much
Involved
314
plotted as the function of p&J CBH+sCBm 0.001 mol dm I ; Systemsr
strongly in the delocalization of the lone pair of N-bases, parAN titularly when pKa of those protonated N-bases (TEA, N-MePip and Morph ) are ence
(see Table). When the diffsrto p tiN(Me3NOH+) between ge3NOH+ and TEAH+, N-MsPipH+, MorphI? is
close
npKa AN
small and equals +0.31, -0.64 and -0.84, respsctively, the intensity of the $,(OH*) is obssrved just as with the symmetrical hydrogen bond similar to the [Me3NO12H+ complex. fact that oxygen is more negativs than strongly delocalized in the -NOHf This work
was partly
supported
l
- N,l
nitrogen
Owing to the the
hydrogen
by Grant
from
proton
is
bridge. MR I-11.
Vie thank Professor Eltbista Winnicka and Miss Joanna Pawlak for their assistance in the preparation of this manuscript. REFERENCES 1 Z. Pawlak, A. wawrzyn6w, 3. Chem. 2
Sot., Faraday Trans I, 79 ( 1983 ) 1523-1531. z. Pswlak, G. Zundel, 3. Fritsch, Electrochimica Acta,
7
29 (1984 )391-395. Z. Pawlak, L.Sobczyk, Adv. Mol. Relaxation Processes, 5 (1973 )99-106. R.L. Dean, J.L. Wood, J. Mol. Structure, 26 (1975 ) 197-213, 215-235. B. Brzezinski, G. Zundel, 3. Cham. SOC.. Faraday Trans II, 72 ( 1976 ) 2127-2137. B. Brzezinski, M. Szafran, Roczniki Chsmii, 51 (1977 ) 1779.1782. H. Romanowski, L. Sobczyk, J. Phys. Chem., 79 (1975)
8
2535.~2541. +F. Costzse,
3 4 5 6
G.R.
Padaanabhan,
G.P.
Cunningham,
Talanta,
11 (1964)93-103. 9
3.F.
Coettee,
Progr.
Phys.
Org.
Chem.,
4 (1966)
45-92.