Vibrational analysis of some hydroxyalkyl substituted oxamides

Spectrochimica AC&. Vol. IOA, No. 6. pp. 1141-1152, I994 Copyright 0 I994 Elscvicr Science Ltd Printed in Great Britain. All rights reserved 05%8539194 $7.00 + 0.00

Pergamon

Vibrational analysis of some hydroxyalkyl substituted oxamides IISEWOLFSand HERMAN 0. DESSEYN Depatment of Chemistry, R.U.C.A., University of Antwap, Gmata~botgerlaan 171,24X0 AntwerP, Belgium SPIRGS

Laboratory of Inorganic (Received

Abstract-

P. PERLRPRs

Chanistry. University of Patras, Rio Patra. Greece

27 October

1993; accepted

‘Ihe vibrational spectra of RHNCGCONHz and

deuterated dexivatives are reported. ‘Ihe sputa

18 November

1993)

RHNCOCONHR (R = (CH$,OH.x = 2.3.4.5)and the

provide direct information on the hydrogen bonding through the position

and profile of several typical amide fundamentals, through the frequency shifts at different tmpmtures

and through the

relative intensities of some Raman bends. All these features indicate amide-amide N-alkyloxamides

and NJ’-dialkyloxamides.

length of the akyl substitwtt. alcohol fun&ma1

hydrogen

honding comparable

with the hydrogen

bond pnttem

in

The hydtogen bonding bdween the hydroxyl groups is dependent on the.

This work must also be regarded as 8 contribution in the charactetisation of the amide and

groups.

INTRODUCTION For several years our group has been engaged in the synthesis and spectroscopy of new ligands of oxamides. In this paper we have extended our work to a series of new oxamide ligands with very interesting coordination possibilities. The new ligands all exhibit two amide functional groups and one or two hydroxyl groups, which can in principle also be protonated on coordination in highly alcalic media. As the repeat unit in biological and industrial materials, the amide functional group is very important. To provide a better understanding of these amide systems, a study of the hydrogen bonding gives an indication of the important intermolecular interactions. In the hydroxyalkyl substituted oxamides different interactions can be considered with the introduction of an additional proton donating group, the hydroxyl group. The occurrence of OH, NH and NH, groups to act as electron acceptors and the carbonyl groups to act as electron donors, means that different hydrogen bond interactions can be considered. These small molecules are very similar to biological systems wherein the same donor and acceptor groups occur. Infrared and Raman spectroscopy provide one of the most sensitive probes of the hydrogen bond. The vAH. &AH and xAH vibrational frequencies are very sensitive to the formation of the hydrogen bond. The former is decreasing while the others are increasing on hydrogen bond formation. The band width is increasing on hydrogen bonding as is extensively studied for the vAH vibration by Bratos [l] and Mar&ha1 [2]. The temperature effect on the hydrogen bonded amide and hydroxyl functions is investigated. Hitherto only the temperature effect on the lcNH mode (Amide V) in hydrogen bonded solid secondary amides has been reported [3]. We also studied the temperature effect on hydrogen bonded systems 143. The obtained qualitative data of the frequency shifts and the decrease of the Av l/2 half band width at lower temperatures can be easily explained. The frequency shift is due to the change in the intermolecular distances and the consequent change in hydrogen bond strength at different temperatures while the decrease in half band width is due to a distribution of geometries with bent hydrogen bonds, by lowering the temperature such a distribution may narrow to a preferred geometry [5]. SA(A) 50:6-I

1141

1142

I. WOLFS et al. EXPJZRIMENTAL

The monosubstituted oxamides have been prepared by the reaction of RNH, COOC.& in alcoholic solution. The disubstituted oxamides were prepared equivalents of RNH, to one mole of CH@OC-COOCH, also in alcoholic products were purified by sublimation or by repeated recrystallization from compounds have all been character&d by mass spectrometry (table 1).

with %NCOby adding two solution. The alcohol. The

The infrared spectra were recorded on a Bruker IFS 113~ Fourier Transform spectrometer, using a liquid nitrogen cooled MCT detector with a resolution of 1 cm-l. The low temperature measurements were performed with a self-designed liquid nitrogen cooled cryostat, consisting of a copper sample holder with a small container which can be filled with liquid nitrogen. This is surrounded by a jacket with KBr windows and placed under vacuum, avoiding condensation on the sample when cooled. From the sample a pellet with KBr as a matrix was made, and this was mounted firmly upon the sample holder. The solid state Raman spectra were recorded on a SPEX model 1403 - 0.85m double monochromator - Raman spectrometer. The spectra were excited by the 514.5 nm line of a Spectra Physics model 2020 Argon ion laser operating at 500 mW. For all the products the scanning range was between 50 cm-l to 4000 cm-l. The spectra were recorded at 1 cm-l intervals with a two second time constant at a spectral slith width of 4 cm-l. Table 1; mass spectral data for H,NCO-CONHR and RHNCO-CONHR (relative intensity between brackets). H2NCO-CONHR, R=(CH2)x0H

RESULTSAND DISCUSSION

All compounds exhibit the (CH2)xOH group. The CH frequencies are sufficiently well known and they are scheduled in the tables without further discussion. The fundamentals of the hydroxyl group all appear as weak and broad bands in the infrared and Raman spectra making the assignments very difficult. Low temperature infrared spectra make these assignments evident as fully explained for the mono- and disubstituted (CH2)20H compound.

RHNCO-CONHR. The fundamentals for the trans secondary amide group are very well known and can easily be assigned in comparison with the N,N’-alkylsubstituted oxamides [6,7,8]. The NJ’-alkylsubstituted oxamides exhibit the trans secondary amide group with the carboxy groups in the trans-planar configuration (Cu structure).

Vibrational

analysis of some hydroxyalkyl

substituted

oxamides

1143

As the positions of both the infrared and Raman amide fundamentals are very well comparable for the (C!H&OH and the alkylderivatives, we can consequently also assume the C, H’N‘ 0 configuration for our compounds (figure 1). The frequency H K difference in the vNH, Amide I, II and III bands between the o+ N’ infrared and Raman spectra clearly prove the inversion centre in kH2)xOH these molecules. Regarding the (CH$,OH group as a point mass the 24 Fieure fundamentals can be given as follows : r=4 A,, + 8B, + 9As + 3Bs. These fundamentals are for the Q-I&OH compound scheduled in table 2, the amide bands for the deuterated compound and the amide fundamentals for the other compounds are given in table 3. Table 3 also contains the data for the C&-derivative indicating that the amide fundamentals are very well comparable. $CHZxpH

The vNH modes all appear in the same region, exhibiting the same intensity, so we can state that the length of the substituent group shows no difference in the sterical hindrance. The vND modes appear in the 2450 cm-* region, in this region we have practically no overtones or combination bands compared with the 3300 cm-l region. Most products however exhibit two bands in this region (except for x = 3 ) from which the highest band is attributed to the vND. The Amide I is for all compounds observed as the most intense band in the infrared spectra, shifts about 10 cm-l to lower frequency on deuteration and appears at lower frequency (25 cm-l) compared with the Raman band. The band shows some shoulders on the low frequency side, probably due to overtones of NC0 deformations. We expect a pure vC=O (Amide I) to shift to lower frequency on cooling, i.e. a greater contribution of resonance form B at lower temperature resulting in a weaker double bond character.

I

I

,&p

‘N’7+o (A)

I 09

The band position is not shifted to lower frequency on cooling, probably due to the fact that the expected lowering due to the high vC=O character is partially neutral&d by the vCN character (20 %) and 6NH character (10 %) of this amide I band. The Amide II and Amide III both exhibit high vCN and 6NH character and are situated in the 1550 and 1230 cm-l regions. The Raman bands appear at slightly higher fkquency for the Amide II and about 50 cm-’ higher for the Amide III band. On deuteration we observe the Amide II’ as the most intense Ramanband at higher frequency than the medium weak infrared band. The Amide III’ @ND) appears as a well defined and relatively intense band in the 950 cm-’ region. The Amide II and Amide III bands shift to higher frequency on cooling as expected for the stronger hydrogen bonding due to the shorter intermolecular distances at lower temperature [4]. These bands both exhibit a high vCN and 6NH character. The stronger hydrogen bonding caused by the shorter intermolecular distances results in a shift to higher frequency for the 6NH mode. So for both the Amide II and Amide III bands we observe the expected shifts to higher frequency. The frequency shift of the amide bands can also be explained by considering the amide-amide hydrogen bonding as a donor-acceptor interaction resulting in longer NH and C=O and shorter CN distances increased by the cooperative effect in the chain in the solid state.

I. WOLFS et al.

1144

vibrational analysis of (CONHCH&H,OH),

l&l&&

Raman 20 ‘C

I.R. 3325 (sh)

3325 (sh)

3328 (w)

3294 (vs)

3287 (vs)

3282 (vs)

3240 (sh)

3224 (m)

3214 (m)

3075 2984 2%3 2940 2916 2882 2847

3075 2984 2%3 2940 2916 2882 2847

3075 2984 2%3 2940 2916 2882 2847

3302 (4)

(sh) (mw) (VW) (VW) (m) (m) (VW)

(sh) (mw) (VW) (VW) (m) (w) (VW)

(sh) (mw) (VW) (VW) (m) (m) (VW)

1654 (vvs) 1636 (sh)

1654 (vvs) 1637 (sh)

2985 (2) 2963 (1) 2950 (4) 2917, (1) 2884 (3)

(1639) 1580 (sh) 1559 (4)

1548 (s) 1503 (ms) 1478 (w) 1446 (m) 1412 (w) 1391 (VW) 1316 (m) 1298 (m)

1549 (s) 1509 (s) 1478 (w) 1446 (m) 1413 (w) 1391 (VW) 1317 (m) 1298 (m)

1013 (w)

1245 (ms) 1206 (vs) 1107 (w) 1059 (s) 1043 (m) 1038 (m) 1014 (w)

1246 (ms) 1206 (vs) 1108 (w) 1059 (s) 1043 (m) 1038 (m) 1015 (w)

825 766 746 658

825 779 747 668

825 786 746 672

1543 (s,br) 1475 (sh,br) 1446 (m) 1406 (VW) 1391 (VW) 1316 (m) 1299 (m) 1243 (ms) 1206 (vs) 1106 (w) 1058 (s) 1041 (m)

(m) (ms,br) (sh) (mw,br)

(m) (ms,br) (mw) (ms)

(m) (s,br) (mw) (s)

543 (ms)

543 (ms)

543 (ms)

481 (m)

481 (m)

481 (m)

Amide I, As Amide I, B,

60I-t A, Amide II, As Amide II, B, WH, B,

1473 (2) 1449 (4) (1406) (1394) 1323 (5) 1304 (5) 1290 (10) 1206 (5) 1110 (2) 1059 (3) 1037 (5)

916 824 780 758

(5) (1) (sh) (2)

(650) 574 (2) 490 (3) 347 (1)

329 m 312 (mw)

vI’JH, A, vNI-&B, vOH, B, overtone

2763 (1) 1686 (5) 1654 (vvs) 1638 (sh)

Assignment overtone

297 (1) 282 (4)

271 (VW) 195 (m) 154 (sh)

Amide III, As Amide III, B, vC-0, B,

vCC. As Amide V, A,, Bs Amide IV, As, B, fiH, B, Amide VI, As Amide VI, B, Amide VII, Bs Amide VII, A, 6NR, As 6NR, B, xNR,B, xNR, A,

Vibrational

analysis of some hydroxyalkyl

substituted

oxamides

1145

Recently N. E. Triggs et al. [9,10] investigated the hydrogen bonding of amides and found a relation between the ratio of the vC=O and vCN intensities in Raman and the hydrogen bonding. In absence of hydrogen bonding (i.e. gas phase or aprotic solvents) the vC=O/vCN intensity ratio in Raman is about 2.5, the vC=O band is the dominant amide band in the spectrum. However on hydrogen bonding the ratio drastically changes to be about 0.2-0.5 with the Amide II and Amide III bands as the most intense Raman bands. For our compounds we clearly observe the Amide III band as the dominating Raman band (Amide I/Amide III = 0.3) and the Amide II band with comparable intensity as the Amide I. On deuteration, where the Amide II’ band has a much higher vCN character compared with the Amide II and III in the non deuterated state, an intensity ratio Amide T/Amide II’ = 0.2 is observed. This indeed indicates strong hydrogen bonding in these molecules. The same intensity ratio has been calculated for the NJ’-dialkyloxamides indicating the same amideamide hydrogen bonding. These intensity variations of the Raman amide bands clearly prove the P.E.D. values obtained from the force field calculations [6,7] and the data obtained by Y. Sagawara [ 1 l] and N. Mirkin [ 121 from ab initio calculations of N-methylacetamide. All compounds have a relatively intense Raman band in the 900-800 cm-l region, which is absent from the infrared spectrum. So this band can be assigned to the Raman active vCC. The position of this vCC clearly shows that there is absolutely no conjugation in this molecule, in contradiction with the sithiooxamides where the vCC is observed around 1000 cm-l. The broad 766 cm-l infrared band disappears on deuteration and shifts to higher frequency on cooling, exhibiting a sharper profile. This band can consequently be assigned to the Amide V band, appearing in the same region for the alkylderivatives. The other fundamentals are tentatively assigned in comparison with the alkyloxamides and need no further specification. In the 3500-3000 cm-l region we expect the vOH, vNH and the overtones of the Amide I and Amide II bands (figure 2). At rmrn temperature an intense vNH at 3294 cm-l with shoulders on the high and low frequency side is observed, at low temperatures (lower spectrum) however a clear band appears at about 3330 cm-l (vC=O (B,) + vC=O (As), 1654 + 1686) due to the Amide I combination band. For the deuterated compound this band is clearly observed as a separate band at slightly lower frequency (3310 cm-‘). The vNH becomes sharper and shifts slightly to lower frequency (3294 cm-l to 3282 cm-‘). This shift of about 10 to 15 cm-l is also observed for the alkylderivadves, so from the position and frequency shift of the vNH which are all similar for the (CH2)xOH compounds and the alkyl substituents we can assume the same amide-amide hydrogen , bonding in both kinds of molecules. At low temperature a new band of medium intensity appears at 3214 cm-l, this band must be due to the vOH. The Amide II combination band (vCN (B,) + vCN (As), 1549 + 1559) appears as a shoulder of the vOH at lower temperatures in the 3100 cm-l region, this band disappears on deuteration. The slightly lower experimental frequencies observed for the Amide I and Amide II overtones I I I , are typical for the small positive anharmonicity also 3500 3000 shown by other types of carbonyl containing -/cm-l d compounds. The 6oH band appears in the infrared spectrum at room temperature as a non well defined Figure 2 shoulder of the Amide II band, at lower temperatures we clearly observe the &OH band as a relatively intense band at higher frequencies (1509 cm-‘) and relatively weak and sharp overtones of the NC0 deformations in

1146

I. WOLFS et al.

the 1470 cm-1 region (figure 3). The CH2 deformation at 1446 cm-l remains as expected unchanged at lower temperatures. A clear 6oH band at 1589 cm-l is observed in the Raman spectrum at -120 ‘C (figure 4)

1600 E&U&

1400 850 600 ii/cm-l d Vcm-l __+ 60H and xOH regions in the infrared spectrum of HO(CH2)2HNCOCONH(CH,),OH. The upper spectrum is obtained at room temperature, the lower at - 196 ‘C.

The xOH generally appears as a weak and broad band in the wide 900 to 600 cm-’ region. In this region two broad bands are observed, which disappear on deuteration (766 cm-l and 658 cm-‘). The profile and position of the 766 cm-l band is very well comparable with the lcNH (Amide V) of the alkyloxamides and can be, considering the position of the vNH, with certainty be ascribed to the xNH mode. At lower temperatures the broad 658 cm-l band shifts to higher frequency and appears as a strong and sharp band at 672 cm-l. This band must have high lcOH character (figure 3). In the room temperature Raman spectrum a very weak and extremely broad band is observed at 650 cm-‘. on cooling however the band shifts to 667 cm-1 and becomes more intense (figure 4).

1650 u

A/cm-’ d

1500 700

A/cm-t e

600

6oH and xOH regions in the Ramanspectrum of HO(CH,),HNCOCONH(CH,),OH. The lower spectrum is obtained at room temperature, the upper at - 120 ‘C.

1147

Vibrational analysis of some hydroxyalkyl substituted oxamides

The binuclear square planar Cu-complexes with the hydroxyl oxamides acting as ligands, coordinate through the deprotonated nitrogen atoms of the amide and the deprotonated oxygen acting as a bridge [ 131. The vOH, 60H and nOH modes are consequently absent from the spectrum of the complex. Another clear difference is situated in the 1100 cm-* to 1000 cm-l region where the intense 1060 cm-l band is shifted to about 990 cm-l in the complex. This 1066 cm-l band shifts to 1040 cm-l on deuteration and has consequently vCO(H) character. The small shift on deuteration and the larger shift on coordination can be explained by the mass effect of the H/D and H/metal substitution. T.&k& typical amide fundamentals for RHNCO-CONHR (R= CH,, (CH2)xOH) and deuterated species. Raman data ar e given between brackets. Flmdammtal

3305 (3316) 3294 (3302) 2446 (2448) 2464 (2465) 2434 (2438) 1654 (1686) 1659 (1685) 1640 (1682) 1648 (1680) 1522 (1559) 1543 (1554) 1496 (1508) 1456++(1505) 1470 1235 (1282) 1243 (1290) 954 (950) 932 (947) 746 (758) 770 (823) 739 (743) 762 (818) 766 (755) 753 (743) 567 (572) 566 (555) 479 (489) 348 (392) 469 (487) 346 (385) 544 (563) 532 (510) 529 (503)

VNH

VND

Am1 Am I’ Am II Am II Am III Am III Am IV Am IV AmV ArnV AmVI AmVI Am VII Am VII

3305 (33 14) 2448 (2461)

3282 (3314) 2456 (2457)

3294 (32%) 2455 (2456)

1652 (1684) 1645 (1679) 1536 (1556) 1450*+ (1502)

1645 (1685) 1639 (1681) 1515 (1555) 1456++(1496)

1652 (1684) 1645 (1679) 1536 (1556) 1456*+ (1556)

1255 (1304) 966 (977) 863+ (822) 852* (8 17) 766 (750) 563 (572) 489 (501) 487 (418) 571 (557) 563 (538)

1214 (1230) 948 (953) 790 (824) 784 (819) 742 (756) 558 (565) 410 (406) 406 (405) 538 (561) 523 (544)

1234 (1267) 942 (941) 788 (785) 781 (777) 733 (738) 530 (540) 497 (497) 493 (493) 537 (550) 516

k*:+Kl-I* The amide hydrogen bonding is similar for all disubstituted compounds, a difference in the hydroxyl hydrogen bonding however is observed according the length of the substituent. An extremely different behaviour is observed for the (CH2)sOH compound where different OH fundamentals are observed, resulting in two different vOH, 60H and YZOHmodes. This is clear from figure 5 where the room temperature and low temperature infrared regions of the vOH are given, and from figure 6 where those of 60H and rcOH are given. The three bands at respectively 3434 cm-l, 3381 cm-l and 3293 cm-l must be ascribed to fundamentals, as they also appear in the Raman spectra (at respectively 3425 cm-l, 3382 cm-l and 3296 cm-l)(figure 7) and show the same profile in the deuterated compound, namely two rather weak bands at respectively 2524 cm-l and 2506 cm-l and the more intense vND at 2454 cm-‘. The second reason to consider these three bands appearing in the 3450-3300 cm-l region as fundamentals is that the position of the 3434 and 3381 cm-’ bands is to high to be considered as overtones and the 3293 cm-l band is to intense. Considering two stretching OH I I modes we also expect two &OH and rrOH vibrations, 3000 3500 i?/cm-l e these bands can be clearly observed in the 1450 cm-t Figure 2 1

1

1

I

I.

I148

WOLFS

et al.

and 1330 cm-l region for the 6OH and at about 590 and 680 cm-l for the rcOH modes. These bands shift to higher frequencies and become sharper on cooling and disappear on deuteration. We already reported that the greatest k-quency shifts on cooling are expected for the strongest hydrogen bonds [4]. I

1500 s

I

Vcm-’ d

1300

750

550

iVcrn-l__)

&OH and nOH regions in the infrared spectrum of HO(CH#INCOCONH(CH,),OH

Table 4 gives the OH fundamentals for x = 2 and x = 5. From this table we can see that the vOH at low temperature for the x= 2 is situated at much lower frequency than the vOH modes for x = 5 indicating a stronger hydrogen bond in x = 2. This is indeed reflected in the higher 6OH and rrOH modes for x = 2 : From this table we can also see that the frequency shift at lower frequency strongly depends on the bond strength and that consequently greater shifts are observed for x= 2. In the same molecule (x=5) where two types of hydrogen bonds have been observed, the vOH shifts are clearly more pronounced for the strongest hydrogen bond. The highest vOH, exhibiting the weakest hydrogen bonding, shifts about 4 cm-l at lower frequency (3438 to 3434 cm-‘) while the 338 1 cm-l band shifts to 3373 cm-l.

Table 4; OH fundamentals for RNHCO-CONHR (R = (CH&J

3500

Aj/cm-’ d Figure ;!

3200

Vibrational

analysis of some hydroxyalkyl

substituted

oxamides

1149

H2NCO-CONHR The N-monosubstituted oxamides have a C, symmetry [6] considering the same symmetry for the monosubstituted hydroxyalkyl derivatives (figure 8) and the (CH2),OH group as a point mass the vibrational representation is given as follows : r = 17A’ + 7A”. These assignments are for the Q-I&OH substituent given in r table 5. The amide bands of the other molecules and those of the W”c*O deuterated compounds are gathered in table 6. In the 3500-3100 cm-l region we expect the vOH, v,NH2, v,NHz &&H As the molecule exhibits a C, and the vNH fundamentals. kcH,MJH symmetry we can also expect the combination bands and overtones of the vC=O, Amide I, II and SNH, vibrations. Fieure The methyl derivative shows two intense and relatively sharp bands assigned to v,NHz and vNH and a weaker and broader band at lowest frequency described to the v,NHz. The monosubstituted hydroxyderivatives all show the same profiles in this region except for the highest v,,NHz band which appears broader in comparison with the v,NHz of the methyl derivative. On cooling we observe a general decrease in frequency and a splitting of this highest frequency (see figure 9). This splitting can be explained by assuming that the v,NHz and vOH practically coincide at room temperature, the frequency shift on cooling is different for the two fundamentals, resulting in the v,NHz at 3374 cm-l and the vOH at 3354 cm-t. This greater shift of the vOH compared with the NH modes has also been observed for the disubstituted compounds. From table 6 we can see that the frequency of the vNH is clearly influenced by the mass of the substituent, but not the intensity, indicating that the sterical hindrance of the substituent is similar for all x values. Also from table 6 we can see that the v,NHz differs in the Kaman spectra by about 40 cm-l, this is due to the fact that the overtones and possible Fermi resonance can alter the position of the v,NHP On deuteration, four distinct bands are observed in the 2500-2300 cm-l region in the Raman spectra. Assuming the frequency ratio to be about 1.35 for the three NH vibrations we can assign the highest I I I 3fl09 band at 2540 cm-l to the v,ND2 and the lowest 3500 Y/cm-t d band at 2360 cm-l to the v,NDz, from the two Fieure 9 remaining bands only the band with the highest frequency at 2500 cm-l clearly shifts to lower frequency with increasing mass, so this band must be ascribed to the vND. The last band at 2450 cm-l must then have high vOD character. The infrared spectrum of the deuterated compound exhibit more bands due to the presence of partially deuterated compound, caused by hydrogen exchange in the KBr pellet, -ND, + Hz0 + -NHD + HDO. The NHD group is character&l by the vNH at about 3300 cm-l and the vND at 2460 cm-l. All compounds exhibit in the 1700-1600 cm-l region the dominant infrared band of the spectrum with shoulders on the high and low frequency side. In the Raman spectrum we clearly observe a rather intense band at 1694 cm-l, shifted to 1677 cm-l on deuteration and two rather weak bands at respectively 1646 cm-l and 1604 cm-‘, the 1646 cm-’ band slightly shifts to lower frequency on deuteration while the 1604 cm-l disappears. As the carbonyl stretching frequency of the primary amide group is always situated at higher frequency compared with the secondary amide, we can assign the vC=O of the primary amide to the 1694 cm-l band in the Kaman spectrum, this band is

I. Wows et al.

1150

observed as a shoulder on the high frequency side of the Amide I band at about 1650 cm-l. This band appears very intense in infrared and rather weak in Raman. Table

vibrational analysis of H2NCO-CONH(CH2)20H.

1604 (sh)

412 340 332 204

(w) (m) (sh) (w)

The 6NHz appears for all products as a shoulder on the low frequency side of the intense carbonyl bands in infrared and as a weak and separate band at 1604 cm-l in Raman. The 6NDz is situated as a rather weak band in the 1150 cm-l region in both infrared and Raman. At low temperatures we expect the carbonyl bands to shift slightly to lower frequency and the @II-I, to higher frequency. The nettoresult is practically no shift and a complete overlap of

Vibrational analysis of some hydroxyalkyl substituted oxamides

1151

the WI$,. The exact position of the band maxima of the two carbonyl frequencies and the &II-I, in infrared is impossible to report, due to the strong overlap arising because the frequency difference which is expected to be about 20 cm-1 is smaller than the half band width of these rather broad bands. Q&&

typical amidebands for RNHCO-CONH, (R=CI-I, , (CH2)xOH) and the deuterated compounds. Raman data are given between brackets.

Fundamental “a@32 “as~2 “NH “ND VW2 VP2 vc=o “Go

Am1 Am I’ Am II Am II vCN vCN(d) Am III Am III’ &NH2 am2 PM2 Pm2 ONHZ am2 =m2 7m2

AmV AmV “OH vOD 6oH 6oD XOH lcOD

CH,

3393 (3393) 2545 (2545) 3330 (3330) 2490 (2495) 3210 (3210) 2380 (2386) (1699) (1677) 1658 (1653) 1640 (1628) 1557 (1561) 1495 (1504) 1403 (1406) 1450 (1445) 1241(1251) 940 (944) 1604 (1600) 1148 (1165) 1107 (1109) 940 (944) 784 (780) 539 653 (650) 485 (480) 724 (723) 460 (480)

3380 (3380) 2533 (2540) 3322 (3322) 2504 (2500) 3192 (3175) 2366 (2360) (1694) (1677) 1654 (1647) 1643 (1645) 1546 (1544) 1497 (1498) 1434 (1438) 1435 (1437) 1261 (1262) 960 (955) 1600 (1604) 1155 (1153) 1100 (1107) 937 (935) 822 (815) 613 (610) 700 (688) 503 (491) 736 (730) 520 (535) 3380 (3380) 2430 (2440) 1561(1564) 1155 (1153) 805 (825) 602 (610) 4

3389 (3371) 2534 (2534) 3317 (3317) 2486 (2487) 3208 (3165) 2340 (2339) (1703) (1675) 1653 (1651) 1649 (1648) 1541(1551) 1496 (1497) 1442 (1443) 1478 (1478) 1263 (1265) 974 (974) 1605 (1604) 1149 (1148) 1108 (1106) 933 (930) 803 611(609) 749 (749) 501(509) 749 (749) 537 (536) 3380 (3380) 2450 (2449) 1600 (1600) 1162 (1151) 782 (779) 611(609) -

3382 (3370) 2538 (253 1) 3314 (3315) 2482 (2480) 3208 (3 169) 2375 (2340) (1707) (1677) 1657 (1651) 1647 (1649) 1547 (1552) 1495 (1492) 1442 (1425) 1465 (1465) 1243 (1243) 978 (977) 1605 (1604) 1155 (1157) 1113 (1110) 931 (936) 758 (741) 612 (608) 747 (741) 519 (512) 747 (741) 519 (512) 3380 (3380) 2453 (2451) 1605 (0604) 1155 (1157) 758 (741) 612 (608)

3381(3366) 2542 (2539) 3308 (3311) 2467 (2467) 3227 (3 165) 2380 (238 1) (1707) (1686) 1652 (1648) 1645 (1646) 1543 (1549) 1492 (1490) 1446 (1449) 1473 (1474) 1242 (1242) 996 (998) 1602 (1607) 1149 (1153) 1112 (1108) 939 (940) 828 (825) 631 (634) 733 (749) 479 (482) 733 (749) 515 (510) 3380 (3380) 2442 (2450) 1602 (1607) 1149 (1153) 796 (810) 609 (612)

The amide bands of the secondary amide group behave similar to the bands observed for the disubstituted compounds and can be easily assigned in comparison with the CH, derivative. The vCN of the primary amide is assigned to the most intense infrared band in the 1450 cm-l region, this band shifts as expected slightly to higher frequency at lower temperature and becomes more intense and appears at higher frequency for the deuterated compound. The shift to higher frequency on deuteration is explained by the high &III2 and pNH, character in the normal compound. The fact that this fundamental arises in the CH, deformation region makes it very easy to locate this band in the Raman spectrum where this vCN appears as a very intense band. The (>NH2and pND2 modes can be easily assigned to well defined

1152

I. WOLFSet al.

bands at about 1110 cm-l and 935 cm-’ respectively. These bands become smaller and shift to higher frequency at low temperature. The oNH,, zNH2, lcNH and zOH are all expected in the 800-600 cm-l region as rather broad bands, shifted to higher frequency on cooling and absent in the deuterated compounds. We assigned the oNH2, TNH, and xNH in comparison with the alkyloxamides. The only remaining band which disappears on deuteration and shifts to higher frequency on cooling is situated at 805 cm-l. This band is then ascribed to the XOH mode. The 6oH mode appears as a broad shoulder on the high frequency of the Amide II band but can easily be recognised as a sharp and rather intense band at higher frequency on cooling as the frequency increase is greater for the &OH than for the Amide II band.

CONCLUSION

In N and N,N’ hydroxyalkylsubstituted oxamides amide-amide hydrogen bonding comparable with the alkylsubstituted oxamides has been observed. The (CH&OH substituent has practically no influence on the position and intensity of the amide bands, as sterical hindrance is similar for all compounds and can be compared with the CH, and C& substituents. Temperature effects indicate intermolecular hydrogen bonding in the amide-amide and hydroxy-hydroxy hydrogen bonding. The amide-amide hydrogen bonding is comparable for the mono and disubstituted compounds, this can be concluded from the position and shift at lower temperature. The hydroxyl-hydroxyl hydrogen bonds appear stronger in the disubstituted compounds. Low temperature infrared bands make the assignments of the OH group frequency obvious.

REFERENCES

[l] S. Bratos,H. Ratajczak.P. Viot in Hydrogen Bonded Liquids. 221, eds. J. C. Dote and J. Teixeira(1991) [2] Y. Mar&al in Hydrogen BondedLiquidq 237. eds. J. C. Don and J. Teixeira(1991) [3] G. Zerbi,G. Pellepiane,.I. Rome Spectrosc. 12, 165 (1982) [4] B. Sloutmaekers.H. 0. Desseyn. Appl. Spectrosc. 45.118 (1991) [S] Teragni.Masetti,Z&i, C&m. f’hys. 28.55 (1978) [6] H. 0. Desseyn. W. T. Van Riel, B. J. Van der Veken. Can. J. Spcctrosc. v]

H. 0. Desseyn, B. J. Van der Veken, M. A. Herman,Spectrochim.

[8] H. 0. Desseyn. W. A. Jacob.M. A. Hennan.Spectrochim.

Actu

Acta

24.98

(1979)

33A. 633 (1977)

2841329 (1972)

[9] N. E. Triggs.R. Thimothy.J. J. Valentini,J. Phys. Chm. 97.5535 (1993) [IO]N. E. Triggs.J. J. Valentini.J. Phy. Chem.96.6922 (1992) [I l] Y. Sugawara,A. Y. Hirakawa.M. Tsuboi,J. Mol. Specrrosc. 108.206 (1984) [12] M. G. Mirkin,S. Ktimm.J. Am. Ckm. Sot. 113.9742 (1991) [13] F. J. Quaeyhaegens,S. P. Perlepes,H. 0. Desseyn, Spectrochim.

Acta

45A, 809 (1989)