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A study of νCN and δCN of some quaternary ammonium compounds
786
Research notes
It can be seen that there is only a relatively small variation in the E values as a result of 2,6dihalogeno substitution. Although in terms of area the variation appears to be somewhat larger-the absorption of the dichloro derivative stronger than in the unsubstituted compound and that of the diiodo derivative no less intense than in the dibromo analog-we believe that little, if any, heavy atom perturbation occurs, the enhancement being more probably due to a substituent effect. The absence of a substantial perturbation might in part be due to the distance of the substituents from the ;C=O groups [6]. Heavy atom perturbation may greatly enhance S, -+ T,,, transitions. Since no new band was observed as a result of dihalogeno substitution, there is no other, lower, triplet level. This is as expected from phosphorescence data [12]. The question arises whether perturbation might be induced in an associated Mulliken electron donor. Our attempts to detect the S, + T,, transition of anthracene complexed with 2,6diiodo-p-benzoquinone were unsuccessful because of the intense charge transfer absorption. Finally, attention is directed to the unusual behavior of 2,6-diiodop-benzoquinone, its n, ‘II excited states being of markedly lower energy than in the other related quinones. Experimental p-Benzoquinone (m.p. 115-116”) was sublimed and then recrystallized from ligroin. 2,6Dichloro-p-benzoquinone was from Eastman Organic Chemicals whereas the dibromo [13] and the diiodo [ 141 compounds were prepared according to the literature. All the dihalogenoquinones were recrystallized twice from ethanol and three times from ligroin. The dichloro derivative melted at 120-121°C, the dibromo at 131-132°C and the diiodo at 17%179°C. Absorption spectra were taken with a Gary 14 Recording Spectrophotometer with both normal and expanded scales. Cells of 1.0 cm and occasionally of 2 cm path were used throughout the work. Almost saturated solutions were prepared in purified ligrom and n-heptane. All work was carried out at 25°C. To be sure that no photochemical or concentration alteration had occurred during the measurements, at the end the spectra were run again. Acknowledgements-The authors wish to express their thanks to the Ford Foundation, the de Amparo B Pesquisa do Brazilian “Conselho National de Pesquisas” and the “Funda@o Estado de S&o Paula” for grants to this Department. Department of Chemistry Faculdade de Filosofia, Ci&cias Universidade de S&o Paul0 S&o Paulo, Braail
[12] M. G. JAYSWAL and R. S. SINGH, Spectrochim. [13] G. S. LEVY, Ann. 210, 158 (1882). [14] R. SEIFERT, J. Prukt. Chem. 28, 437 (1883).
Spectrochimica
G. CILENTO D. L. SANIOTO K. ?bTNER
e Letras
Acta 21, 1597 (1965).
Acta, Vol. 24A, pp. 788 to 788. Pergamon Press 1068.
Printed in Northern Ireland
A study of I++~ and 8&H of some quaternary ammonium compounds (Received 17 October
1967)
Ah&&--Infrared spectra of seven quaternary ammonium halides of diverse structure were examined in 4000-250 cm-l region. Absorption bands of medium to strong intensity were noted in 900-980 cm-l region and of weak intensity in 400-480 cm-l region. The bands were common to all compounds. The bands were thought to be the C--N stretching vibrations and deformation modes respectively.
Research notes
787
A NUMBERof investigators have concerned themselves with vibrational spectra of quaternary ammonium salts. Most of the studies have been confined to an examination of the infrared spectra of symmetrical [l-7] and unsymmetrical [7] tetra alkyl ammonium halides. Some uncertainty exists in the assignments of the medium to strong bands in the region of 900-1200 cm-l. For example, EBSWORTFI and SHEPPARD[l] reported the following bands with their assignments in this region. 1294(m) v,,x; 946(vs) CHs rocking; 917(m) ? On the other hand, LORENZELLI and MSLLER[2] and BOTTLERand GEDDES[6] made the following assignments in this region. 1290(m) CIIs rooking; 965 + 947 + 927(vs) vca Recently, VAN SENDEN[S] contirmedthe assignmentsof bands in this region by substitution 1sN for 14N in several n-alkyltrimethylammonium halides. The substitution caused approximately a 10 cm-l shift in the band positions. This paper reports the vibrational spectra of seven quaternary ammonium ions of diverse chemical structure; six iodides and one bromide. The salts examined were as follows: iodides; butyrlcholine, n-heptyl-, phenyl- and cyclopropyltrimethylammonium, cyclohexyl- and propargylcholine ether and phenylcholine ether bromide. Expetimental The halides utilized were synthesized in this laboratory with the exception of cyclopropyltrimethylammonium which was obtained from K and K Laboratories. (Plainview, New York). All substances were recrystallized twice from ethanol-ether mixtures and stored in vacua over CaCl,. The bromide and iodide salts gave no evidence of being hygroscopic, however, they were handled by dry-box techniques. The infrared spectra were recorded in the 4000-250 cm-l region, with a Beckman IR-10 spectrophotometer. The samples were studied at 25°C as dispersions in potassium bromide pellets.
Reads and dimmion An examination of the infraredspectra of seven quaternary ammonium salts revealed several absorption bands in the 900-980 cm-l region of medium to strong intensity. Bands of weak intensity were noted in 400480 cm-l region. These bands are common to all of the halides. The chemical structures and frequencies of the bands and their assignments are given in Table 1. According to the data presented, there is a close similarity of positions and intensitiesof the absorption bands although the compounds are of diverse chemical struoture. These data would indicate that the bands are not easily affected by differencesin chemical structure. For example, note the similarity in positions on the bands of phenyltrimethyl ammonium iodide and tetramethyl ammonium iodide. [l] [S] [3] [4] [S] [6] [7] [S]
E. A. V. EBSWORTEand N. SEEPP~~D,Speefrochim.Acta 18,261(1959). V. LORENZELLI and K. D. MILLER, Camp. Rend. %l, 1483 (1960). J. T. EDBALL,J. C?wm. Phye. 6, 225 (1937). Science 84,423 (1936). R. A. Hxa~coox and L. &~.ARION, Can. J. Chem. 84, 1782 (1966). F. NERDELand W. LEF~MAN, Chem. Ber. OS, 2420 (1969). G. L. BOTTLERand A. L. GEDDES,Spectrochim.Acta al, 1701 (1965). K. Nm SHI, T. GOTO and M. OUEI, Bull. Chem. Sot. Japan 80,403 (1967). K. G. Vm SENDEN,Rec. Trav. Chim. 84, 1469 (1963).
788
Research notes Table
1. Frequencies and assignments of substituted
tetrarnethyl-ammonium
R-N+(CH,), vCN+ (cm-~)
R=
ions &N+ (cm-‘)
921 s 942 s 961”8
461 w
915 * 945 8 966 B
451 m
-O-CH,-CH,-
912 “S 948 ve 971”s
455 m
\ -O-CH,-CH,-
445 w
-
926 “B 950 ve 979 8
-
912 m 940 “B 945 vs
415 w
916 m 944 vs 975 m
452 w
CH,-(CH,),-
905 8 920 m 965 s
448~
CH,
915m 927’ 942 v.¶ 947* 948”s 966.
450 w
0 II CH,(CH,),-CO-CH,-CH, HCEC-CH,-O-CH*-CH*-
0 0 0/ \_ S
/
CH’\CH_ CH/
v = stretohing; 6 = bending; s = strong; v8 = very strong; m = medium; * Frequency assigned in this region by LORENZELLIand MOLLER[2].
w = weak.
Recently COBURN [Q] reported that the infrared spectra of 21 choline esters showed absorption bands of medium intensity near 950 cm- l. These bands believed to be associated with the groups -O--CI&,-CH,-N were in all probability C--N stretching vibrations.
Department of Pharmacology and Toxicology University of Missi881$@ Medical Center 2500 North State Street Jack8on, Mias&wippi
A. S. HUME W. C. HOLLAND
Department of Chemistry U&versity of Illinoks Urbana, Illinoi8
F. FRY
[Q] W. C. COBURN, Southern Research Institute, Birmingham, Alabama, personal communication.
BpectrochhnicsActa, Vol. 24A pp. 788 to 790. PergamonPress 1968. Printed in Northern Ireland
Infrared spectra of coordinated acrylonitrile (Received 2 October 1967) Abstract-The infrared spectra of a variety of acrylonitrile-metal complexes have been investigated in the NaCl region. The frequency shifts of certain bands indicate that both resonance and inductive effects increase in the acrylonitrile molecule upon coordination. The strongest evidence is obtained from examination of the vinyl out-of-plane hydrogen deformations, in which a croesover of the vinyl twist and wag frequencies is observed.
Research notes
It can be seen that there is only a relatively small variation in the E values as a result of 2,6dihalogeno substitution. Although in terms of area the variation appears to be somewhat larger-the absorption of the dichloro derivative stronger than in the unsubstituted compound and that of the diiodo derivative no less intense than in the dibromo analog-we believe that little, if any, heavy atom perturbation occurs, the enhancement being more probably due to a substituent effect. The absence of a substantial perturbation might in part be due to the distance of the substituents from the ;C=O groups [6]. Heavy atom perturbation may greatly enhance S, -+ T,,, transitions. Since no new band was observed as a result of dihalogeno substitution, there is no other, lower, triplet level. This is as expected from phosphorescence data [12]. The question arises whether perturbation might be induced in an associated Mulliken electron donor. Our attempts to detect the S, + T,, transition of anthracene complexed with 2,6diiodo-p-benzoquinone were unsuccessful because of the intense charge transfer absorption. Finally, attention is directed to the unusual behavior of 2,6-diiodop-benzoquinone, its n, ‘II excited states being of markedly lower energy than in the other related quinones. Experimental p-Benzoquinone (m.p. 115-116”) was sublimed and then recrystallized from ligroin. 2,6Dichloro-p-benzoquinone was from Eastman Organic Chemicals whereas the dibromo [13] and the diiodo [ 141 compounds were prepared according to the literature. All the dihalogenoquinones were recrystallized twice from ethanol and three times from ligroin. The dichloro derivative melted at 120-121°C, the dibromo at 131-132°C and the diiodo at 17%179°C. Absorption spectra were taken with a Gary 14 Recording Spectrophotometer with both normal and expanded scales. Cells of 1.0 cm and occasionally of 2 cm path were used throughout the work. Almost saturated solutions were prepared in purified ligrom and n-heptane. All work was carried out at 25°C. To be sure that no photochemical or concentration alteration had occurred during the measurements, at the end the spectra were run again. Acknowledgements-The authors wish to express their thanks to the Ford Foundation, the de Amparo B Pesquisa do Brazilian “Conselho National de Pesquisas” and the “Funda@o Estado de S&o Paula” for grants to this Department. Department of Chemistry Faculdade de Filosofia, Ci&cias Universidade de S&o Paul0 S&o Paulo, Braail
[12] M. G. JAYSWAL and R. S. SINGH, Spectrochim. [13] G. S. LEVY, Ann. 210, 158 (1882). [14] R. SEIFERT, J. Prukt. Chem. 28, 437 (1883).
Spectrochimica
G. CILENTO D. L. SANIOTO K. ?bTNER
e Letras
Acta 21, 1597 (1965).
Acta, Vol. 24A, pp. 788 to 788. Pergamon Press 1068.
Printed in Northern Ireland
A study of I++~ and 8&H of some quaternary ammonium compounds (Received 17 October
1967)
Ah&&--Infrared spectra of seven quaternary ammonium halides of diverse structure were examined in 4000-250 cm-l region. Absorption bands of medium to strong intensity were noted in 900-980 cm-l region and of weak intensity in 400-480 cm-l region. The bands were common to all compounds. The bands were thought to be the C--N stretching vibrations and deformation modes respectively.
Research notes
787
A NUMBERof investigators have concerned themselves with vibrational spectra of quaternary ammonium salts. Most of the studies have been confined to an examination of the infrared spectra of symmetrical [l-7] and unsymmetrical [7] tetra alkyl ammonium halides. Some uncertainty exists in the assignments of the medium to strong bands in the region of 900-1200 cm-l. For example, EBSWORTFI and SHEPPARD[l] reported the following bands with their assignments in this region. 1294(m) v,,x; 946(vs) CHs rocking; 917(m) ? On the other hand, LORENZELLI and MSLLER[2] and BOTTLERand GEDDES[6] made the following assignments in this region. 1290(m) CIIs rooking; 965 + 947 + 927(vs) vca Recently, VAN SENDEN[S] contirmedthe assignmentsof bands in this region by substitution 1sN for 14N in several n-alkyltrimethylammonium halides. The substitution caused approximately a 10 cm-l shift in the band positions. This paper reports the vibrational spectra of seven quaternary ammonium ions of diverse chemical structure; six iodides and one bromide. The salts examined were as follows: iodides; butyrlcholine, n-heptyl-, phenyl- and cyclopropyltrimethylammonium, cyclohexyl- and propargylcholine ether and phenylcholine ether bromide. Expetimental The halides utilized were synthesized in this laboratory with the exception of cyclopropyltrimethylammonium which was obtained from K and K Laboratories. (Plainview, New York). All substances were recrystallized twice from ethanol-ether mixtures and stored in vacua over CaCl,. The bromide and iodide salts gave no evidence of being hygroscopic, however, they were handled by dry-box techniques. The infrared spectra were recorded in the 4000-250 cm-l region, with a Beckman IR-10 spectrophotometer. The samples were studied at 25°C as dispersions in potassium bromide pellets.
Reads and dimmion An examination of the infraredspectra of seven quaternary ammonium salts revealed several absorption bands in the 900-980 cm-l region of medium to strong intensity. Bands of weak intensity were noted in 400480 cm-l region. These bands are common to all of the halides. The chemical structures and frequencies of the bands and their assignments are given in Table 1. According to the data presented, there is a close similarity of positions and intensitiesof the absorption bands although the compounds are of diverse chemical struoture. These data would indicate that the bands are not easily affected by differencesin chemical structure. For example, note the similarity in positions on the bands of phenyltrimethyl ammonium iodide and tetramethyl ammonium iodide. [l] [S] [3] [4] [S] [6] [7] [S]
E. A. V. EBSWORTEand N. SEEPP~~D,Speefrochim.Acta 18,261(1959). V. LORENZELLI and K. D. MILLER, Camp. Rend. %l, 1483 (1960). J. T. EDBALL,J. C?wm. Phye. 6, 225 (1937). Science 84,423 (1936). R. A. Hxa~coox and L. &~.ARION, Can. J. Chem. 84, 1782 (1966). F. NERDELand W. LEF~MAN, Chem. Ber. OS, 2420 (1969). G. L. BOTTLERand A. L. GEDDES,Spectrochim.Acta al, 1701 (1965). K. Nm SHI, T. GOTO and M. OUEI, Bull. Chem. Sot. Japan 80,403 (1967). K. G. Vm SENDEN,Rec. Trav. Chim. 84, 1469 (1963).
788
Research notes Table
1. Frequencies and assignments of substituted
tetrarnethyl-ammonium
R-N+(CH,), vCN+ (cm-~)
R=
ions &N+ (cm-‘)
921 s 942 s 961”8
461 w
915 * 945 8 966 B
451 m
-O-CH,-CH,-
912 “S 948 ve 971”s
455 m
\ -O-CH,-CH,-
445 w
-
926 “B 950 ve 979 8
-
912 m 940 “B 945 vs
415 w
916 m 944 vs 975 m
452 w
CH,-(CH,),-
905 8 920 m 965 s
448~
CH,
915m 927’ 942 v.¶ 947* 948”s 966.
450 w
0 II CH,(CH,),-CO-CH,-CH, HCEC-CH,-O-CH*-CH*-
0 0 0/ \_ S
/
CH’\CH_ CH/
v = stretohing; 6 = bending; s = strong; v8 = very strong; m = medium; * Frequency assigned in this region by LORENZELLIand MOLLER[2].
w = weak.
Recently COBURN [Q] reported that the infrared spectra of 21 choline esters showed absorption bands of medium intensity near 950 cm- l. These bands believed to be associated with the groups -O--CI&,-CH,-N were in all probability C--N stretching vibrations.
Department of Pharmacology and Toxicology University of Missi881$@ Medical Center 2500 North State Street Jack8on, Mias&wippi
A. S. HUME W. C. HOLLAND
Department of Chemistry U&versity of Illinoks Urbana, Illinoi8
F. FRY
[Q] W. C. COBURN, Southern Research Institute, Birmingham, Alabama, personal communication.
BpectrochhnicsActa, Vol. 24A pp. 788 to 790. PergamonPress 1968. Printed in Northern Ireland
Infrared spectra of coordinated acrylonitrile (Received 2 October 1967) Abstract-The infrared spectra of a variety of acrylonitrile-metal complexes have been investigated in the NaCl region. The frequency shifts of certain bands indicate that both resonance and inductive effects increase in the acrylonitrile molecule upon coordination. The strongest evidence is obtained from examination of the vinyl out-of-plane hydrogen deformations, in which a croesover of the vinyl twist and wag frequencies is observed.