Complexation of formaldoxime with water. Infrared matrix isolation and theoretical studies

Article abstract of DOI:10.1016/j.saa.2011.10.069

The 1:1, 1:2 and 2:1 formaldoxime-water complexes isolated in the argon matrices have been studied by help of FTIR spectroscopy and MP2/6-311++G(2d,2p) method. The calculations predicted the stability of the three CH ₂NOH?H₂O isomeric complexes, three CH ₂NOH?(H₂O)₂ ones and one (CH ₂NOH)₂?H₂O complex. The analysis of the experimental spectra and their comparison with theoretical ones indicated that both the 1:1 and 1:2 complexes trapped in solid argon have the most stable cyclic structures stabilized by the O-H?O and O-H?N bonds between the formaldoxime and water molecules. In the 1:2 complex formaldoxime interacts with the water dimer, one H₂O molecule acts as a proton acceptor for the OH group of formaldoxime whereas the second H₂O molecule acts as a proton donor toward the nitrogen atom of the formaldoxime molecule. In the (CH₂NOH)₂?H₂O complex the OH group of the water molecule acts as a proton donor toward one of the oxygen atoms of the formaldoxime cyclic dimer.

Full text of DOI:10.1016/j.saa.2011.10.069

Spectrochimica Acta Part A 86 (2012) 461–466
Contents lists available at SciVerse ScienceDirect
Spectrochimica Acta Part A: Molecular and
Biomolecular Spectroscopy
journal homepage: www.elsevier.com/locate/saa
Complexation of formaldoxime with water. Infrared matrix isolation and
theoretical studies
Barbara Golec, Małgorzata Mucha, Zofia Mielke∗
Faculty of Chemistry, University of Wrocław, Joliot-Curie 14, 50-383 Wrocław, Poland
a r t i c l e i n f o
a b s t r a c t
Article history:
The 1:1, 1:2 and 2:1 formaldoxime-water complexes isolated in the argon matrices have been studied by
help of FTIR spectroscopy and MP2/6-311++G(2d,2p) method. The calculations predicted the stability of
the three CH2NOH· · ·H2O isomeric complexes, three CH2NOH· · ·(H2O)2 ones and one (CH2NOH)2· · ·H2O
complex. The analysis of the experimental spectra and their comparison with theoretical ones indicated
that both the 1:1 and 1:2 complexes trapped in solid argon have the most stable cyclic structures sta-
bilized by the O–H· · ·O and O–H· · ·N bonds between the formaldoxime and water molecules. In the 1:2
complex formaldoxime interacts with the water dimer, one H2O molecule acts as a proton acceptor for
the OH group of formaldoxime whereas the second H2O molecule acts as a proton donor toward the nitro-
gen atom of the formaldoxime molecule. In the (CH2NOH)2· · ·H2O complex the OH group of the water
molecule acts as a proton donor toward one of the oxygen atoms of the formaldoxime cyclic dimer.
© 2011 Elsevier B.V. All rights reserved.
Received 17 August 2011
Received in revised form 23 October 2011
Accepted 31 October 2011
Keywords:
Matrix isolation
Hydrogen bond
Formaldoxime
Ab initio calculations
Water complexes
1. Introduction
bonding behaviour of formaldoxime in complexes with water is
of particular interest as both interacting molecules have multiple
Formaldoxime, H2C NOH, is the simplest member of the oximes
family, an important biological and chemical group of compounds.
It is a structural isomer of formamide and is being considered as
a potential interstellar molecule [1]. The >C NOH group, char-
acteristic for oximes, has three distinct hydrogen bonding sites
and, so, oximes can form a variety of hydrogen bonds. Two of the
three sites, the nitrogen and oxygen atoms, are the hydrogen-bond
acceptor sites and the (N)OH group is a proton donor. Although
the intermolecular hydrogen bond motifs involving oximes play
an important role in molecular design [2,3] the hydrogen bonding
abilities of oximes were much less studied than the properties of
many other molecules like for example carboxylic acids, amides or
halides [4].
More attention was devoted to the self-association of oximes
than to their hetero-association. A number of reports concerns
self-association of acetone oxime: the studies were performed in
solution [5–7], in the solid state [8–10] and more recently in the
gas phase [11]. The self-aggregation of many other oximes has been
also studied [12–16]. We reported recently the results of the study
on the formaldoxime dimers [17], and on the formaldoxime com-
plexes with nitrogen [18] and nitrous acid [19]. Here we present the
results of the infrared matrix isolation and MP2/6-311++G(2d,2p)
study on the formaldoxime complexes with water. The hydrogen
hydrogen bonding sites.
2. Experimental
2.1. Infrared matrix isolation studies
Formaldoxime was generated from formaldoxime trimer
hydrochloride (Aldrich, >98%) in the following way. The small
amount of salt was placed in a glass flask connected to the vac-
uum vessel of the cryostat. Upon heating to 323–338 K the salt
decomposed releasing gaseous formaldoxime. The H2O/Ar mixture
with concentration varying from 1/500 to 1/1200 and formal-
doxime were simultanously deposited onto a gold plated copper
mirror held at 11 K by a closed cycle helium refrigerator (Air Prod-
ucts, Displex 202A). The concentration of formaldoxime in the
CH2NOH/H2O/Ar mixtures was varied by changing the flow rate
of argon gas as well as the temperature of hydrochloride salt.
Infrared spectra with resolution 0.5 cm−1 were recorded in a reflec-
tion mode with a Bruker 113v spectrometer using liquid N2 cooled
MCT detector.
2.2. Computational details
The Gaussian 03 program [20] was used for geometry optimiza-
tion and harmonic vibrational calculations. The structures of both
monomers (CH2NOH, H2O) and the structures of the CH2NOH–H2O
complexes with the stoichiometry 1:1; 1:2 and 2:1 were fully
∗
Corresponding author. Tel.: +48 71 3757475; fax: +48 71 3282348.
E-mail address: zofia.mielke@chem.uni.wroc.pl (Z. Mielke).
1386-1425/$ – see front matter © 2011 Elsevier B.V. All rights reserved.
doi:10.1016/j.saa.2011.10.069

462
B. Golec et al. / Spectrochimica Acta Part A 86 (2012) 461–466
˚
optimized at the MP2 level of theory with the 6-311++G(2d,2p)
basis set. Vibrational frequencies were computed both for the
monomers and for the complexes. Interaction energies were cor-
rected by the Boys–Bernardi full counterpoise procedure [21].
0.008 and 0.006 A, respectively, in the complexes IB and IC. Conse-
quently, the calculations result in 135 and 97 cm−1 decrease of the
OH stretching wavenumbers of H2O in IB and IC as compared to the
H2O monomer (see Tables S1 and S2 in Supplementary Data).
In the most stable formaldoxime–water complex of the 1:2 sto-
ichiometry the formaldoxime molecule interacts with the water
dimer. One of the two water molecules of (H2O)2 acts as a proton
donor toward the nitrogen atom and the second water molecule
serves as a proton acceptor for the NOH group of CH2NOH. So, the
cyclic 1:2 complex, like the most stable 1:1 one, is stabilized by
the O–H· · ·N and O–H· · ·O bonds between formaldoxime and the
water dimer. All heavy ring atoms are placed in the plane of the
formaldoxime molecule. The O10H11 bond of H2O attached to the
nitrogen atom and the O5H6 bond of CH2NOH are elongated by
3. Results
3.1. Infrared spectra
The infrared spectra of the CH2NOH/Ar and H2O/Ar matrices
agree well with those reported in the literature [22–24]. In the
spectra of the CH2NOH/H2O/Ar matrices a set of new absorptions
appeared in the vicinity of H2O and CH2NOH absorptions that can
be safely assigned to the complexes formed between water and
formaldoxime. The spectra of the CH2NOH/H2O/Ar matrices are
shown in Fig. 1. The wavenumbers of all observed product bands
are collected in Table 1.
The new absorptions can be separated into three groups assum-
ing as criteria their dependence on the water or formaldoxime
concentrations and their behaviour after matrix annealing. The
bands assigned to group I (at 3692.3, 3543.3, 3481.8, 1427.1, 1348.9,
1162.8, 948.3 and 902.0 cm−1) occur in the matrices with the low
water and formaldoxime concentrations, their intensities decrease
after matrix annealing. The bands belonging to group II (at 3698.0,
3415.3, 3272.2, 1374.2, 1178.8, 946.2 and 936.7 cm−1) are observed
in matrices with the higher water concentration and their relative
intensities grow with respect to the intensities of the group I bands
when the water concentration in the matrix increases. The bands
II show small sensitivity to matrix annealing. In turn, the absorp-
tions assigned to group III (at 3339.7, 3208.8, 1376.0, 1184.8, 971.6,
968.2, 943.1 and 929.7 cm−1) strongly increase after matrix anneal-
ing to 33 K for 10 min which correlates well with an increase of the
(CH2NOH)2 concentration.
˚
0.019, 0.018 A, respectively, and the N4–O5 bond is shortened by
0.022 A as compared to the corresponding distances in H2O and
CH2NOH monomers. The larger perturbations of the OH distances
˚
in the 1:2 complex are accompanied by the shorter H· · ·N and H· · ·O
˚
bonds as compared to the 1:1 structure (R(N· · ·H): 2.15, 1.90 A
˚
and R(O· · ·H): 1.96, 1.77 A in the 1:1 and 1:2 complexes, respec-
tively). In contrast with the five-membered ring in the 1:1 complex,
the seven-membered ring in the 1:2 one allows for the more
effective interaction between CH2NOH and (H2O)2. The O–H· · ·N
and O–H· · ·O hydrogen bonds in the 1:2 complex are close to
linear (the corresponding angles are 163.0◦, 171.9◦, respectively)
whereas in the 1:1 structure they strongly deviate from linear-
ity (the corresponding angles are 126.1◦, 142.9◦). The interaction
energy of the IIA complex equals to −48.18 kJ mol−1 as compared
to −18.74 kJ mol−1 for IA. Such a large difference in the interac-
tion energies between IA and IIA is a consequence of much stronger
O–H· · ·N and O–H· · ·O bonds in IIA (the interaction energy of (H2O)2
is calculated to be ca. 22 kJ mol−1 only) [25]. In IIB the CH2NOH
molecule interacts with (H2O)2, like in the IIA structure, but in con-
trast to IIA, the water dimer is attached to the formaldoxime OH
group which acts as a proton donor for one water molecule and
as a proton acceptor for the other water molecule of (H2O)2. The
three oxygen atoms of the cyclic ring formed by the three O–H· · ·O
bonds do not lie in the plane of CH2NOH, the NOOO dihedral angle
is 107◦. The IIB complex is less stable by 11.4 kJ mol−1 than the IIA
one. The IIC structure can be considered as a combination of IA and
IC structures. One of the two bonded H2O molecules serves as a
proton donor toward a nitrogen atom and as a proton acceptor for
the OH group of CH2NOH like in IA and the second H2O molecule
serves as a proton donor toward the oxygen atom of CH2NOH as in
the IC structure. The interaction energy of IIC is slightly lower than
the sum of the interaction energies of IA and IC (−30.59 – (−18.74
– 9.65)) = −2.2 kJ mol−1. The additional stabilization energy of IIC is
most probably due to the cooperative effect.
3.2. Theoretical studies
The structures of the formaldoxime–water complexes of
the 1:1, 1:2 and 2:1 stoichiometry were optimized by the
MP2/6-311++G(2d,2p) method. The calculations resulted in three
stationary points for the 1:1 and 1:2 complexes between CH2NOH
and H2O (IA, IB, IC and IIA, IIB and IIC, respectively) and in one sta-
tionary point for the 2:1 complex (IIIA). All otpimized structures
are shown in Fig. 2, their binding energies are also presented. The
geometrical parameters of the optimized structures are collected
in Table 2 and in Table S1 in Supplementary Data. In Table S2 the
calculated wavenumbers for all optimized structures are collected.
The most stable 1:1 complex, IA, is stabilized by two hydrogen
bonds O–H· · ·N and O–H· · ·O, which form a cyclic structure. In the
O–H· · ·N bond the N atom of CH2NOH serves as a proton acceptor
for the OH group of water and in the O–H· · ·O bond the OH group of
CH2NOH acts as a proton donor toward the oxygen atom of water.
In the complex of the 2:1 stoichiometry between CH2NOH and
H2O (IIIA) the water molecule serves as a proton donor toward one
of the oxygen atoms of the centrosymmetric CH2NOH dimer like
in the IC complex. The centrosymmetric CH2NOH dimer may serve
as a proton acceptor only, as the two OH groups of the CH2NOH
molecules are involved in the formation of the six-membered cen-
trosymmetric ring with two O–H· · ·N bonds. The interaction energy
of IIIA equals to −48.56 kJ mol−1 and is slightly lower than the sum
of the interaction energies of centrosymmetric CH2NOH dimer [17]
˚
The O7H8 bond of H2O is elongated by 0.008 A and the O5H6 bond
˚
of CH2NOH by 0.009 A as compared to the corresponding bonds
of the monomers; the N4–O5 bond of CH2NOH is shortened by
˚
0.012 A in the complex (see Fig. 2 for atoms numbering). The elon-
gation of the OH bonds of the water and formaldoxime molecules
is accompanied by the decrease of their corresponding OH stretch-
ing frequencies. The calculations result in 175, 102 cm−1 red shifts
of the ꢀ(OH) frequencies of CH2NOH and H2O after complex for-
mation. In the other two structures water acts as a proton donor
either toward the nitrogen atom (IB) or toward the oxygen atom
(IC) of CH2NOH. The two structures are stabilized by one strong
hydrogen bond only which leads to a decrease of their interaction
energies by 8.41 kJ mol−1 or by 9.09 kJ mol−1, respectively, as com-
pared to the IA structure. The O7H8 bond of H2O is elongated by
and IC complex (−36.51 – 9.65) = −46.16 kJ mol−1
.
4. Discussion
The three groups of bands identified in the spectra of the
CH2NOH/H2O/Ar matrices evidence formation of three kinds of
complexes in the solid argon. The stoichiometry and the structure
of the three kinds of complexes are discussed below.

B. Golec et al. / Spectrochimica Acta Part A 86 (2012) 461–466
463
Fig. 1. Four spectral regions in the spectra of the matrices: H2O/Ar = 1/1000 (a); CH2NOH/Ar (b) and CH2NOH/H2O/Ar = x/1000/Ar (c and d) registered after matrix deposition
at 11 K (c) and after its annealing to 33 K for 10 min (d).
Table 1
Observed wavenumbers (cm−1
) for the formaldoxime–water complexes trapped in argon matrices and the comparison of the observed wavenumbers shifts
(ꢁꢀ = ꢀcomplex − ꢀmonomer) with the calculated ones for the IA, IIA and IIIA structures. Calculated intensities (km mol−1) are given in parentheses, HB – hydrogen bonded
group.
Assignment
Monomers
CH2NOH–H2O
CH2NOH–(H2O)2
(CH2NOH)2–H2O
(CH2NOH)2
ꢀexp.
ꢀexp.
I
ꢁexp.
ꢁꢀcalc. IA
ꢀexp II
ꢁꢀexp.
ꢁꢀcalc IIA
ꢀexp. III
ꢁꢀexp.
ꢁꢀcalc IIIA
CH2NOH
ꢀOH
3620.7
3481.8
−138.9
−175 (264)
3272.2
−348.5
−393(220)
3339.7
3208.8
−281.0
−411.9
−324 (1538)
−419 (482)
3329.0–3289.7a
ıCH2
ıNOH
1408.3
1314.2
1427.1
1348.9
+18.8
+34.7
+43 (50)
+60 (56)
1374.2
1178.8
946.2
+60.0
+25.1
−6.9
+76 (35)
+24(16)
−4 (38)
1376.0
–
1184.8
–
971.6
968.2
943.1
929.7
–
+61.8
–
+31.1
–
+85 (18)
+72 (62)
+32 (23)
+17 (4)
1369.9
1180.2
949.0
ꢂCH2
ωCH2
1153.7
953.1
1162.8
948.3
+9.1
+13 (13)
−4.8
−4 (39)
+16.8
+23 (41)
−10.0
+46.6
–
−2 (40)
+37(68)
+14 (123)
ꢀNO
886.4
880.2
902.0
+18.7
+21 (99)
936.7
+53.4
+50 (90)
915.8
H2O
ꢀOH
3735.0
3638.0
3692.3
3543.3
−42.7
−94.7
−45 (122)
3698.0
−37.0
−58 (134)
−57 (63)
–
–
–
–
−38 (124)
−94 (178)
–
3415.3
–
–
−222.7
–
ꢀHBOH
−102 (254)
−247 (583)
−323 (1349)
a
Broad absorption, see Ref. [16] for details.

464
B. Golec et al. / Spectrochimica Acta Part A 86 (2012) 461–466
Fig. 2. MP2/6-311++G(2d,2p) optimized structures of the 1:1, 1:2 and 2:1 complexes between formaldoxime and water. The interaction energies are given in parentheses
and expressed in kJ mol−1
.
Table 2
Selected calculated geometrical parametersa of the most stable structures of the formaldoxime–water 1:1, 1:2 and 2:1 complexes.
Parameter
Monomer
IA
IIA
IIIA
Parameter
Monomer
IA
IIA
IIIA
r C1–N4
r N4–O5
r O5–H6
r O7–H8
1.278
1.409
0.961
0.958
0.958
0.958
0.958
0.961
1.409
1.278
1.397
0.970
0.966
0.958
1.279
1.387
0.979
0.974
0.958
0.977
0.958
1.278
1.402
0.981
0.965
0.958
␪ C1–N4–O5
␪ N4–O5–H6
␪ H8–O7–H9
␪ O7–H8–N4
␪ O5–H6–O7
␪ O7–H8–O10
␪ O10–H11–N4
␪ H11–O10–H12
␪ O5–H6–N12
␪ O11–H10–N4
␪ C1–H3–O7
110.5
102.2
104.3
111.8
101.7
105.3
126.1
142.9
112.4
103.5
105.5
112.7
101.4
105.0
r O7–H9
171.9
156.3
163.0
105.7
r O10–H11
r O10–H12
r O11–H10
r N12–O11
R H6· · ·O7
R H8· · ·O10
R N4· · ·H8
R N4· · ·H11
R N4· · ·H10
R N12· · ·H6
R O5· · ·H8
R H3· · ·O7
(173.6)b
0.978
1.391
155.4
153.5
132.9
155.9
1.962
2.146
1.773
1.833
(1.956)b
␪ O7–H8–O5
1.898
␸ N4–O5–H6–O7
␸ O5–H6–O7–H8
␸ N4–O5–O7–H9
␸ O5–N4–H11–O10
␸ N4–O5–O7–O10
␸ O5–N4–O10–H12
␸ N4–O5–H8–O7
␸ N4–O5–N12–O11
3.2
−6.1
−6.4
5.2
110.9
−10.7
−1.2
117.6
(1.889)c
(1.889)c
1.899
1.847
1.983
2.442
−94.3
161.7
17.3
−1.6
(0.0)c
a
Bond lengths in Å, angles in (◦)
In parentheses are presented the geometrical parameters of the (H2O)2 dimers.
In parentheses are presented the geometrical parameters of the (CH2NOH)2 dimers.
b
c

B. Golec et al. / Spectrochimica Acta Part A 86 (2012) 461–466
465
The bands I are assigned with confidence to a 1:1 CH2NOH· · ·H2O
complex of the IA structure. They appear in the spectra of matri-
ces with low CH2NOH and H2O concentrations and diminish after
matrix annealing which is characteristic for the 1:1 complexes.
Three bands of this group appear in the OH stretching region
(at 3481.8, 3543.3 and 3692.3 cm−1) and exhibit 138.9, 94.7 and
42.7 cm−1 red shifts with respect to the ꢀ(OH) wavenumber of
CH2NOH and ꢀas and ꢀs wavenumbers of the H2O monomer, respec-
tively. Such a spectral pattern indicates that both CH2NOH and
water act as proton donors and this occurs only in the IA struc-
ture. The participation of the (N)OH group in the (N)O–H· · ·O(H2)
hydrogen bonding with water molecule is also confirmed by an
increase of the NOH bending and N–O stretching wavenumbers
(by 34.7 and 18.7 cm−1) of CH2NOH after complex formation. In
(N)OH group of nitrous acid and the oxygen atom of one water
molecule, and by the O–H· · ·N bond between the OH group of the
second H2O molecule and the nitrogen atom of the acid. How-
ever nitrous acid is a much stronger proton donor and a weaker
proton acceptor than formaldoxime, so, the (N)O–H· · ·O bond is
much stronger and the O–H· · ·N one much weaker in the trans-
HONO· · ·(H2O)2 complex than in the CH2NOH· · ·(H2O)2 one. The
observed shift of the trans-HONO ꢀOH stretching wavenumber after
complex formation is as large as 750 cm−1
.
The bands III, whose intensities strongly increase after matrix
annealing, are assigned to the complex of the 2:1 stoichiometry
between the formaldoxime and water molecules. In our recent
paper [17] we demonstrated that in argon matrices doped with
formaldoxime the centrosymmetric CH2NOH dimers are readily
formed after matrix annealing. One may expect that in the matrices
doped both with CH2NOH and H2O the formaldoxime dimer may
interact with the water molecule forming the (CH2NOH)2· · ·H2O
complex. In centrosymmetric CH2NOH dimer the OH groups of the
two CH2NOH molecules serve as proton donors toward the nitrogen
atoms; in the 2:1 complex the water molecule is attached to one of
the oxygen atoms of (CH2NOH)2 as illustrated in Fig. 2. The bands
III appear very close to the absorptions of (CH2NOH)2 as expected
for the (CH2NOH)2· · ·H2O complex (see Table 1). Unfortunately, we
did not identify the absorptions due to the perturbed water vibra-
tions, they probably coincide with the other numerous absorptions
that appear in the corresponding region. The two bands at 3339.7
and 3208.8 cm−1 are assigned to the perturbed (N)OH stretching
vibrations of (CH2NOH)2. The attachment of the water molecule
to (CH2NOH)2 lowers its symmetry to C1 removing the center of
symmetry, so, both OH stretching vibrations of (CH2NOH)2 become
active in the (CH2NOH)2· · ·H2O complex whereas only one vibra-
tion was observed for (CH2NOH)2 (in the 3329.0–3289.7 cm−1
region as a broad band with some structure). The identified NOH
bending, CH2 rocking and wagging, and N–O stretching bands
have very close values to those observed for (CH2NOH)2. Table 1
shows that the observed wavenumbers shifts for the bands III
are in accord with the calculated ones for the (CH2NOH)2· · ·H2O
complex.
Table 1 the observed bands shifts, ꢁꢀexp (ꢁꢀ = ꢀcomplex − ꢀmonomer
)
of the group I are compared with the calculated bands shifts, ꢁꢀcalc
,
for the IA structure. As one can see there is a very good agreement
between the experimental shifts and calculated ones for IA. The
arrangement of the water molecule with respect to formaldoxime
in the cyclic IA complex enables the formation of two hydrogen
bonds (N)O–H· · ·O and N· · ·H–O(H). However, both the (N)O–H· · ·O
and N· · ·H–O(H) angles (142.9◦, 126.1◦) strongly deviate from lin-
earity which weakens the strength of these bonds. The IA complex
has analogous structure to that observed for the water complex
with hydroxylamine. [26] The H2NOH· · ·H2O complex of the 1:1
stoichiometry has also a cyclic structure stabilized by the N· · ·H–O
and O–H· · ·O bonds. The ꢀ(OH) stretching wavenumbers of hydrox-
ylamine and water are red shifted by 94, 200 cm−1, respectively,
after complex formation.
The bands II are attributed to the 1:2 CH2NOH· · ·(H2O)2 com-
plex IIA, which is the most stable one among the three optimized
1:2 complexes. Three bands belonging to this complex were iden-
tified in the OH stretching region at 3698.0, 3415.3 cm−1 and at
3272.2 cm−1. The first two absorptions are 37.0 and 222.7 cm−1
red shifted with respect to the water monomer bands at 3735.0,
3638.0 cm−1, respectively, and the third band, at 3272.2 cm−1
,
is 365.8 or 348.5 cm−1 shifted toward lower wavenumbers with
respect to the OH stretches of water (at 3638.0 cm−1) or formal-
doxime (3620.7 cm−1). The bands at 3698.0 and 3415.5 cm−1 are
attributed to the perturbed OH stretches of the water molecules
in the 1:2 complex, the first one corresponds to the vibration of
the nonbonded OH group and the second one to the OH stretch of
H2O acting as a proton donor toward the second H2O molecule.
The band at 3272.2 cm−1 is assigned to the coupled OH stretches of
the (N)OH and (H)OH groups acting as proton donors for the water
and formaldoxime molecules; the other absorption corresponding
to these two coupled stretches has not been identified. However
the analysis of the 3700–3150 cm−1 region is quite difficult as in
addition to the absorptions due to the formaldoxime–water com-
plexes there appear also bands due to the water and formaldoxime
aggregates. The characteristic absorptions of the CH2NOH· · ·(H2O)2
complex appearing at 1374.2, 936.7 cm−1 are attributed to the NOH
in plane bending and NO stretching of the formaldoxime molecule.
They exhibit 60 and 53.4 cm−1 shift toward higher wavenumbers
with respect to the CH2NOH monomer and provide strong evidence,
in addition to the identified OH stretching vibrations, for the forma-
5. Conclusions
The 1:1, 1:2 and 2:1 complexes between formaldoxime and
water were identified in the CH2NOH/H2O/Ar matrices and
their structures were determined on the basis of the per-
formed MP2/6-311++G(2d,2p) calculations. The theoretical studies
indicate the stability of three CH2NOH· · ·H2O structures, three
CH2NOH· · ·(H2O)2 ones and one (CH2NOH)2· · ·H2O structure. Com-
parison of the experimental spectra with the theoretical ones
evidenced that only the most stable 1:1 and 1:2 cyclic com-
plexes involving the O–H· · ·O and O–H· · ·N bonds between the
water and formaldoxime molecules are present in the matrix.
The interaction energy for the cyclic CH2NOH· · ·(H2O)2 com-
plex is −48.18 kJ mol−1 whereas for the CH2NOH· · ·H2O complex
is −18.74 kJ mol−1
. The interaction between the two water
molecules in the 1:2 complex does not account for the relatively
large difference in interaction energies between the two com-
plexes. This is due to the fact that the O–H· · ·O and O–H· · ·N
bonds in the seven-membered CH2NOH· · ·(H2O)2 complex are
almost linear and much stronger than in the five-membered
CH2NOH· · ·H2O complex where the hydrogen bonds strongly
deviate from linearity. In the (CH2NOH)2· · ·H2O complex the
water molecule is attached to one of the two oxygen atoms
of the centrosymmetric CH2NOH dimer lowering its symme-
try to C1 and activating the symmetric ꢀs(OH) (CH2NOH)2
mode.
tion of the IIA complex. In Table 1 the observed bands shifts, ꢁꢀexp
,
for the bands II are compared with the calculated ones, ꢁꢀcalc, for
the IIA structure; as one can see the two sets of wavenumbers shifts
show very good agreement. Much stronger perturbation of the
formaldoxime vibrations in the 1:2 complex as compared to the 1:1
one is first of all due to the more favoured interaction through the
(N)O–H· · ·O and O–H· · ·N bonds in the seven-membered cyclic ring
than in the five-membered one. Similar cyclic, seven-membered
structure, was observed for the trans-HONO· · ·(H2O)2 complex [27].
The complex was stabilized by the (N)O–H· · ·O bond, between the

466
B. Golec et al. / Spectrochimica Acta Part A 86 (2012) 461–466
Acknowledgement
[11] M. Albrecht, P. Zielke, C.A. Rice, M.A. Suhm, J. Mol. Struct. 880 (2008) 2–13.
[12] A. Behrens, W.A.P. Luck, B. Mann, Ber. Bunsen-Ges. Phys. Chem. 82 (1978)
47–48.
[13] G.A. Kurkchi, L.M. Zimina, J. Struct. Chem. 29 (1988) 552–556.
[14] P.R. Olivato, D.S. Ribeiro, R. Rittner, Y. Hase, D. del Pra, G. Bombieri, Spectrochim.
Acta A 51 (1995) 1479–1495.
The authors acknowledge the Wrocław Supercomputer Centre
(WCSS) for providing computer time and facilities.
[15] P.R. Olivato, D.S. Ribeiro, J. Zukerman-Schpector, G. Bombieri, Acta Crystallogr.
B 57 (2001) 705–713.
Appendix A. Supplementary data
[16] E.A. Bruton, L. Brammer, F.C. Pigge, C.B. Aakeröy, D.S. Leinen, New J. Chem. 27
(2003) 1074–1094.
Supplementary data associated with this article can be found, in
the online version, at doi:10.1016/j.saa.2011.10.069.
[17] B. Golec, Z. Mielke, J. Mol. Struct. 844–845 (2007) 242–249.
[18] B. Golec, J. Grzegorzek, Z. Mielke, Chem. Phys. 353 (2008) 13–18.
[19] B. Golec, A. Bil, Z. Mielke, J. Phys. Chem. A 113 (2009) 9434–9441.
[20] M.J. Frisch, et al., Gaussian 03, Revision C. 02, Gaussian Inc., Wallingford, CT,
2004.
References
[21] S.F. Boys, F. Bernardi, Mol. Phys. 19 (1970) 553–566.
[22] A. Heikkilä, M. Pettersson, J. Lundell, L. Khriachtchev, M. Räsänen, J. Phys. Chem.
A 103 (1999) 2945–2951.
[1] S. Al-Dallal, R. Bannai, H. Manaa, Adv. Space Res. 30 (2002) 1433–1438.
[2] F.H. Allen, W.D.S. Motherwell, P.R. Raithby, G.P. Shields, R. Taylor, New J. Chem.
23 (1999) 25–34.
[23] R.M. Bentwood, A.J. Barnes, W.J. Orville-Thomas, J. Mol. Spectrosc. 84 (1980)
391–404.
[3] T. Steiner, Angew. Chem. Int. Ed. 41 (2002) 48–76.
[4] A.J. Barnes, J. Mol. Struct. 100 (1983) 259–280.
[24] G.P. Ayers, A.D.E. Pullin, Spectrochim. Acta 32 A (1976) 1629–1639.
[25] M.J. Frisch, J.E. Del Bene, J.S. Binkley, H.F. Schaefer III, J. Chem. Phys. 84 (1986)
2279–2289.
[26] G.A. Yeo, T.A. Ford, Vib. Spectrosc. 2 (1991) 173–181.
[27] A. Olbert-Majkut, Z. Mielke, K.G. Tokhadze, Chem. Phys. 280 (2002) 211–
227.
[5] S. Califano, W. Lüttke, Z. Phys. Chem. 5 (1955) 240.
[6] S. Califano, W. Lüttke, Z. Phys. Chem. 6 (1956) 83–104.
[7] T. Di Paolo, C. Sandorfy, Can. J. Chem. 51 (1973) 1441–1442.
[8] D. Hadzˇi, L. Premru, Spectrochim. Acta A 23 (1967) 35–44.
[9] W.C. Harris, S.F. Bush, J. Chem. Phys. 56 (1972) 6147–6155.
[10] G. Keresztury, J. Mol. Struct. 36 (1977) 155–157.