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Iodine monochloride complexes of substituted tetrazoles
Notes
2027
Similar spectral shifts of carbonyl stretching vibrations with titanium complexes were observed by YAMAMOTOca3), SUSZm) and LAPPERT.~ ) It would be expected that a decrease in the absorption frequency of the carbonyl band would result if the oxygens of the carboxyl group participated in bridging to the titanium. The resultant shift is shown in Table 2. D. SCHWARTZ C. JOHNSON J. LUDWIG M. L. MORRIS
College of Chemistry and Phystes North Dakota State University Fargo, North Dakota (U.S.A.) tl0~ A. YAMAMOTOand S. KAMBARA, Nippon Kagaku Zasshi 80, 1239 (1959). tm B. P. Susz and A. LACHAVANNE, Helv. Chim. Acta 41,634 (1958). i~'-,~ M. F. LAPPERT, J. Chem. Soc. 542 (1962).
J. Inorg. Nucl. Chem., 1964, Vol. 26, pp. 2027 to 2028. Pergamon Press Ltd. Printed in Northern Ireland
Iodine monochloride complexes of substituted tetrazoles* (Received 22 April 1964) SUBSTXTUTEDtetrazoles and especially pentamethylenetetrazole (hereafter abbreviated as PMT) have been shown to behave as Lewis bases. They are capable of forming relatively stable complexes with halogens ~1) and with metal ionsJ 2'3~ On the other hand, they have essentially no basic properties in water and are only protonated in strongly acidic solvents such as formic acidJ 2'4) Tetrazoles are also noted for their wide spectrum of physiological activity on the central nervous system which varies from strong stimulants to depressants. The specific activity depends on seemingly minor changes in the nature and/or the position of the substituent group. ~ Since it is not inconceivable that physicochemical properties of neurotropie drugs may be related to their pharmacological action, a thorough investigation of physicochemical properties of tetrazoles was initiated some time ago. The work reported in this paper is a part of that study. Formation constants of P M T (a strong convulsant drug) complexes with iodine, iodine bromide and iodine monochloride have been determined spectrophotometrically, m The respective formation constants (in lit. mole -1) are; 7.5, 1.5 × 102 and 2-0 > 103. EXPERIMENTAL Compounds used in this investigation were 7-methyl PMT, 8-see-butyl PMT and 8-t-butyl PMT. They were obtained from the Knoll Pharmaceutical Co. These compounds were available only in small quantities and had to be used without further purification. The source and the purification procedure for iodine monochloride and for carbon tetrachloride were described in a previous publication.el) Spectrophotometric measurements were made on a Beckman D U spectrophotometer in quartz cells of 1.00 k 0.01 cm pathlength at room temperature, 25 ~ 2 °. Methods of preparation of solutions and their standardization were described previously. (l~ In general, work was done with 10 -2 10-3 M solutions. RESULTS Repeated attempts were made to prepare solid iodine monochloride complexes of PMT derivatives (analogous to PMT.ICI) by mixing equimolar (ca. 0.1 M ) solutions of the P M T derivative and of * Paper XXIII in the series "Studies on the Chemistry of Halogens and of Polyhalides" Paper XXll, J. Amer. Chem. Soe. 85, 891 (1963). (1) A. I. PoPov, C. CASTELLANI-BISland M. CgArr, J. Amer. Chem. Soc., 80, 6513 (1958). (2~ A. I. Popov and R. D. HOLM, J. Amer. Chem. Soc. 81, 3250 (1959). ~3~ C. H. BRUBAKER and G. L. GILBERT, Inorg. Chem. 2, 1216 (1963). ~4~A. I. PoPov and J. C. MARSHALL, J. lnorg. Nucl. Chem. 24, 1667 (1962). ~3~ F. W. SCHUELER, S. C. WANG, R. M. FEATHERSTONEand E. G. GROSS, J. Pharmacol. Exptl. Therap. 97, 266 (t949) and references listed therein.
2028
Notes
iodine monochloride in carbon tetrachloride. Contrary to expectations, no precipitate was obtained. Gradual evaporation of the resulting solutions yielded oily residues which decomposed on standing Method of continuous variation ~e) on more dilute solutions, however, unambiguously indicated the presence of 1 : 1 complexes. Formation constants of the three complexes were then determined spectrophotometrically using a previously described technique. ~7~ The results are given in Table 1. In all cases the complexes are stronger than the corresponding complex for the unsubstituted PMT. This is in agreement with the expected effect of the substituent groups on the donor properties of the tetrazole ring. It is interesting to speculate whether the bonding between the tetrazole ring and the iodine monochloride occurs through one of the nitrogen atoms or through the ~r electrons of the double bonds. Recently, JONASSENet al. ~8~postulated that in iron (I1) complexes with 5-substituted tetrazoles, the bonding occurs through the 7r electrons associated with the nitrogen-nitrogen TABLE 1 . - - F O R M A T I O N CONSTANTS OF IODINE MONOCHLORIDE COMPLEXES OF SUBSTITUTED PENTAMETHYLENETETRAZOLES IN E E l 4 AT 2 5 ° C
8-sec-butyl PMT
7-methyl P M T E
2
8-t-butyl PMT
E
complex
500 11.4 480 12.4 450 13.1 430 18.8 350 167 Kay ~ 2"55
g*
Kf × 10 3 2
0.271 0.261 0.267 0.281 0.263 -k 0"18 ×
2'48 2'71 2.57 2.35 2-66 103
complex
500 12.7 480 12.4 450 14.4 430 20.4 350 171 Kay -- 3"20
E
g*
Kf × 10 -3
0-259 0.267 0.281 0.297 0.278 ~ 0'50 ×
3"70 3'45 3'05 2-67 3.14 10s
3.
complex
g*
Kf × 10 -3
500 480 450 430
10'9 10'7 13.0 20.2
0.250 0-246 0.250 0-260
3.52 3.65 3.52 3-21
Kay -- 3"48 ± 0"22 × 103
* c~ = degree of dissociation double bond. In our case the strength of the complex (as compared, for example, with benzene-IC1 complex) seems to favor anitrogen-iodine bond. Ofcourse, the bonding in 1,5-substituted tetrazole complexes may be quite different from the ones where the donor is a 5-substituted tetrazole anion.
Acknowledgement--The authors gratefully acknowledge the support of this work by the NSF Grant G-14318. They are also indebted to Dr. R. O. HAucr: of the Knoll Pharmaceutical Company for the substituted P M T derivatives. J. W . V A U O H N
Department 0["Chemistry Northern Illinois University De~alb, Illinois D~partment of Chemistry Michigan State University East Lansing, Michigan (~ P. JoB. Ann. Chim. 9, 113 (1928). (7~ A. I. PoPov and R. H. RYGG, J. Amer. Chem. Soc. 79, 4622 (1957).
T . C . WEHMAN A . I . PoPov
(a~ H. B. JONASSEN, A. D. HARRIS, R. M. HERBER and G. K. WESTHEIM, J. Amer. Chem. Soc. 2927 (1963).
85,
J. Inorg. Nucl. Chem,, 1964, Vol. 26, pp. 2028 to 2033. Pergamon Press Ltd. Printed in Northern Ireland
Concurrent carbon dioxide absorption and oxygen evolution by lithium peroxide THERE HAS been considerable interest of late in the preparation, characterization, and application o f metal peroxides, superoxides, and ozonides for the purification of the breathing atmospheres
2027
Similar spectral shifts of carbonyl stretching vibrations with titanium complexes were observed by YAMAMOTOca3), SUSZm) and LAPPERT.~ ) It would be expected that a decrease in the absorption frequency of the carbonyl band would result if the oxygens of the carboxyl group participated in bridging to the titanium. The resultant shift is shown in Table 2. D. SCHWARTZ C. JOHNSON J. LUDWIG M. L. MORRIS
College of Chemistry and Phystes North Dakota State University Fargo, North Dakota (U.S.A.) tl0~ A. YAMAMOTOand S. KAMBARA, Nippon Kagaku Zasshi 80, 1239 (1959). tm B. P. Susz and A. LACHAVANNE, Helv. Chim. Acta 41,634 (1958). i~'-,~ M. F. LAPPERT, J. Chem. Soc. 542 (1962).
J. Inorg. Nucl. Chem., 1964, Vol. 26, pp. 2027 to 2028. Pergamon Press Ltd. Printed in Northern Ireland
Iodine monochloride complexes of substituted tetrazoles* (Received 22 April 1964) SUBSTXTUTEDtetrazoles and especially pentamethylenetetrazole (hereafter abbreviated as PMT) have been shown to behave as Lewis bases. They are capable of forming relatively stable complexes with halogens ~1) and with metal ionsJ 2'3~ On the other hand, they have essentially no basic properties in water and are only protonated in strongly acidic solvents such as formic acidJ 2'4) Tetrazoles are also noted for their wide spectrum of physiological activity on the central nervous system which varies from strong stimulants to depressants. The specific activity depends on seemingly minor changes in the nature and/or the position of the substituent group. ~ Since it is not inconceivable that physicochemical properties of neurotropie drugs may be related to their pharmacological action, a thorough investigation of physicochemical properties of tetrazoles was initiated some time ago. The work reported in this paper is a part of that study. Formation constants of P M T (a strong convulsant drug) complexes with iodine, iodine bromide and iodine monochloride have been determined spectrophotometrically, m The respective formation constants (in lit. mole -1) are; 7.5, 1.5 × 102 and 2-0 > 103. EXPERIMENTAL Compounds used in this investigation were 7-methyl PMT, 8-see-butyl PMT and 8-t-butyl PMT. They were obtained from the Knoll Pharmaceutical Co. These compounds were available only in small quantities and had to be used without further purification. The source and the purification procedure for iodine monochloride and for carbon tetrachloride were described in a previous publication.el) Spectrophotometric measurements were made on a Beckman D U spectrophotometer in quartz cells of 1.00 k 0.01 cm pathlength at room temperature, 25 ~ 2 °. Methods of preparation of solutions and their standardization were described previously. (l~ In general, work was done with 10 -2 10-3 M solutions. RESULTS Repeated attempts were made to prepare solid iodine monochloride complexes of PMT derivatives (analogous to PMT.ICI) by mixing equimolar (ca. 0.1 M ) solutions of the P M T derivative and of * Paper XXIII in the series "Studies on the Chemistry of Halogens and of Polyhalides" Paper XXll, J. Amer. Chem. Soe. 85, 891 (1963). (1) A. I. PoPov, C. CASTELLANI-BISland M. CgArr, J. Amer. Chem. Soc., 80, 6513 (1958). (2~ A. I. Popov and R. D. HOLM, J. Amer. Chem. Soc. 81, 3250 (1959). ~3~ C. H. BRUBAKER and G. L. GILBERT, Inorg. Chem. 2, 1216 (1963). ~4~A. I. PoPov and J. C. MARSHALL, J. lnorg. Nucl. Chem. 24, 1667 (1962). ~3~ F. W. SCHUELER, S. C. WANG, R. M. FEATHERSTONEand E. G. GROSS, J. Pharmacol. Exptl. Therap. 97, 266 (t949) and references listed therein.
2028
Notes
iodine monochloride in carbon tetrachloride. Contrary to expectations, no precipitate was obtained. Gradual evaporation of the resulting solutions yielded oily residues which decomposed on standing Method of continuous variation ~e) on more dilute solutions, however, unambiguously indicated the presence of 1 : 1 complexes. Formation constants of the three complexes were then determined spectrophotometrically using a previously described technique. ~7~ The results are given in Table 1. In all cases the complexes are stronger than the corresponding complex for the unsubstituted PMT. This is in agreement with the expected effect of the substituent groups on the donor properties of the tetrazole ring. It is interesting to speculate whether the bonding between the tetrazole ring and the iodine monochloride occurs through one of the nitrogen atoms or through the ~r electrons of the double bonds. Recently, JONASSENet al. ~8~postulated that in iron (I1) complexes with 5-substituted tetrazoles, the bonding occurs through the 7r electrons associated with the nitrogen-nitrogen TABLE 1 . - - F O R M A T I O N CONSTANTS OF IODINE MONOCHLORIDE COMPLEXES OF SUBSTITUTED PENTAMETHYLENETETRAZOLES IN E E l 4 AT 2 5 ° C
8-sec-butyl PMT
7-methyl P M T E
2
8-t-butyl PMT
E
complex
500 11.4 480 12.4 450 13.1 430 18.8 350 167 Kay ~ 2"55
g*
Kf × 10 3 2
0.271 0.261 0.267 0.281 0.263 -k 0"18 ×
2'48 2'71 2.57 2.35 2-66 103
complex
500 12.7 480 12.4 450 14.4 430 20.4 350 171 Kay -- 3"20
E
g*
Kf × 10 -3
0-259 0.267 0.281 0.297 0.278 ~ 0'50 ×
3"70 3'45 3'05 2-67 3.14 10s
3.
complex
g*
Kf × 10 -3
500 480 450 430
10'9 10'7 13.0 20.2
0.250 0-246 0.250 0-260
3.52 3.65 3.52 3-21
Kay -- 3"48 ± 0"22 × 103
* c~ = degree of dissociation double bond. In our case the strength of the complex (as compared, for example, with benzene-IC1 complex) seems to favor anitrogen-iodine bond. Ofcourse, the bonding in 1,5-substituted tetrazole complexes may be quite different from the ones where the donor is a 5-substituted tetrazole anion.
Acknowledgement--The authors gratefully acknowledge the support of this work by the NSF Grant G-14318. They are also indebted to Dr. R. O. HAucr: of the Knoll Pharmaceutical Company for the substituted P M T derivatives. J. W . V A U O H N
Department 0["Chemistry Northern Illinois University De~alb, Illinois D~partment of Chemistry Michigan State University East Lansing, Michigan (~ P. JoB. Ann. Chim. 9, 113 (1928). (7~ A. I. PoPov and R. H. RYGG, J. Amer. Chem. Soc. 79, 4622 (1957).
T . C . WEHMAN A . I . PoPov
(a~ H. B. JONASSEN, A. D. HARRIS, R. M. HERBER and G. K. WESTHEIM, J. Amer. Chem. Soc. 2927 (1963).
85,
J. Inorg. Nucl. Chem,, 1964, Vol. 26, pp. 2028 to 2033. Pergamon Press Ltd. Printed in Northern Ireland
Concurrent carbon dioxide absorption and oxygen evolution by lithium peroxide THERE HAS been considerable interest of late in the preparation, characterization, and application o f metal peroxides, superoxides, and ozonides for the purification of the breathing atmospheres