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Chemistry of imidobis(sulphuryl chloride)—IV measurements of physical properties of imidobis(sulphuryl chloride)
J. inorg, nucl. Chem. Vol. 40, pp. 200%2008
0022-1902/78/1201-2005/$02.0010
© PergamonPress Ltd.. 1978. Printed in Great Britain
CHEMISTRY OF IMIDOBIS(SULPHURYL CHLORIDE)--IV MEASUREMENTS OF PHYSICAL PROPERTIES OF IMII)OBIS(SULPHURYL CHLORIDE) RAM CHAND PAUL, PRATIBHA KAPOOR, RAMESH KAPOOR and RAJENDER DEV VERMA Department of Chemistry, Panjab University, Chandigarh-160014,India (Received 28 November 1977; received for publication 1 July 1978)
Abstract--Density, viscosity and specific conductance have been measured at 50 interval between 25 to 500 for imidobis(sulphurylchloride).The surface tension, freezing point and cryoscopicconstant have also been determined. Its IR and proton NIVlRspectra have been recorded. Relativeacidity strength measurementsin acetic acid suggestthat imidobis(sulphurylchloride) is a stronger protonic acid than HBr, HSO3C1and (CF3)2POOH.
INTRODUCTION Although imidobis(sulphuryl chloride) was synthesized in 196611] little interest has been shown in its solvent properties. The only known physical properties are its melting and boiling points and the refractive index. We have extended our earlier investigations[2-5] of this solvent.
RESULTS AND DISCUSSION Imidobis(sulphuryl chloride) is a stable, colourless, crystalline solid at room temperature. It is highly sensitive to moisture and decomposes on exposure to moist air. It can, however, be stored for longer periods, if kept in a frozen state in an air tight vessel. It is soluble in several organic solvents, viz. CCL, CHCI3, CH2C12, C6I-I6, C6HsNO2, CH3NO2, CH3CN and SO2C12. It dissolves in EXPERIMENTAL diethylether, tetrahydrofuran, acetone and methanol with lmidobis(sulphuryl chloride) was prepared by the published exothermic reaction. It is insoluble in petroleum ether, method[l]. It was purified by 2 to 3 fractional crystallizations. n-hexane and cyclohexane. The molar conductance values Acetic acid (AnalaR) was purified by a published method[6]. The purified acid had a specific conductance of less than 0.5 x of its millimolar solutions in nitrobenzene and acetonitrile 10-Tfl-)cm -'. Analytical grade CCh, C t H t , CtHsNO2 and are 30 and 130 ~ - t cm 2 mole-~ respectively. The values lie C6I'14(NO2)2were purified by the standard methods. POCI3 and well within the range expected for 1 : 1 electrolytes in these SO2CI2 were fractionally distilled and the fractions distilling at solvents[9]. Its 1 : I electrolytic nature in CH3NO2 has been 104-105" and 68-69* respectively were collected. Preparation of confirmed from a value of 210 for the slope of the straight alkali metal salts, MN(SO2CI)2,where M = Li, Na, K and Rb has line obtained by drawing a plot of Ao- Ac against ~/C [ 10]. been reported earlier[4]. The cryoscopic molecular weight determinations in nitroConductivity measurementswere carried out on a ToshniwalCI benzene (ca. 1.5% wlw solution) gave a mean value of 212. 01/01 conductivity bridge. The cell constant (0.20era-t) of a dip Its density, viscosity, surface tension and conductance type cell was determined by the standard metbod[7] and was have been measured at different temperatures and the periodically checked. Measurements were made in an oil bath thermostat which could be adjusted to any desired temperature and values are given in Table 1. The high boiling point, long maintainedto an accuracy of -+0.05*.Measurementscould be made liquid range and high viscosity suggest that, like suiphuric at temperatures below the freezing point of the pure solvent ca. 25 acid, imidobis(sulphuryl chloride) is a highly associated to 30"C, because imidobis(sulphurylchloride) supercools readily liquid and hydrogen bonding and proton transfer reactions and no problem was encountered with spontaneous crystallization will be important in this medium. Its density varies linearly of the solvent during the measurements. with temperature (*C) and its viscosity decreases markedly The cryoscope was a double walled sealed vessel having a with temperature. The plot of log ~ against I/T is a straight single-arm magnetic stirrer[8]. Temperatures were measured to line between the temperatures 308 to 3230K. This implies -+0.005*with a calibrated Beckmannthermometer. The cryoscope was immersedin a thermostat whichwas kept at ca. 1.0-+0.2° below that there is no structural break down between these the freezing point of the solution in the cryoscope. In order to temperatures. The activation energy of viscous flow has measure the freezing point, the solution was first melted and then been computed using the relation allowed to cool by placing it in the thermostat. When it had supercooled by about 0.5-1°, crystallization was induced by d log 77= slope = EJ2.303R increasingthe rate of stirring.The temperature of the solutionthen d(1/T) rose rapidly and reached a maximum value where it remained constant for several minutes. The steady maximum temperature and has been found to be 7.0 kcal mole -t. The high value of was taken as the freezing point. The density was measured by means of a bicapillarypycnometer its self-conductance suggests that imidobis(sulphuryl which was calibrated with mercury at different temperatures. The chloride) is a fairly dissociated acid and the following viscosity was measured with the help of a Ubbelohde type self-ionization may occur. viscometer.The surface tension was determined by usingTraube's Stalagmometer and the drop pipette method. 2HN(SO2C1)2 ~ [H2N(SO2CI)2]+ + [N(SO2C1)2]-. The IR spectrum of the acid was recorded in silver chloride and (1) polythene plates as liquid with a Perkin-Elmer Model 621 grating spectrophotometer. The spectra of the alkali metal salts of imidobis(sulphurylchloride) were recorded as Nujol mullson sodium The computed values of the molar conductivity (/z = K x chloride plates. The proton NMR spectrum of imidobis(sulphuryl VM) are given in Table 1. Treatment of the conductivity chloride) was recorded on a Varian A-(d)spectrometeras liquidand data by the method used for the viscosity gives values for as 20% (v/v) solution in CCI¢using TMS as the external standard. Ex and E~, (activation energies of ionic mobilities) as 6.6
2005
RAM CHAND PAUL et al.
2006
Table 1. Density, viscosity, surface tension and conductivity of imidobis(sulphuryl chloride) between 25 and 50°C Temperature (°C) Property Density (g cm-3) Viscosity (cP) Sp. cond.x 10~ (fl-' cm -I) Molar cond.x 105 (1),-'cm 2 mole-')
25
30
35
40
1.8663 --
1.8596 --
1.8528 13.3323
1.8465 10.9216
1.8397 9.1949
1.8331 7.7506
0.480
0.576
0.693
0.814
0.960
1.131
111.70
132.00
55.04
66.30
80.04
45
94.36
50
39.97
Surface tension (dynes/cm)
Table 2. 1R frequencies (cm-~) of imidobis(sulphuryl chloride)? and its alkali metal salts~: HN(SO2CI)2 3200sb, 2940w, 2860shw, 2750m,2650mb, 1665wb, 1412s, 1300s, 1202s, 1165s,972s, 870s b, 815sh, 600s b, 500s, 420w, 360m, 325w,280w LiN(SO2CI)2 1600w, 1430m,1260w, l130s, 1050m,710m,650m NaN(S02CI)2 1400sh, 1340s, 1260w, l150s, 1070s,920w, 900w, 865m, 815w, 770s, 728w KN(SO2Cl)2 1430m, 1315sh, 1280s, 1168s, 1065s, 1000s,880m, 850s, 690w RbN(SO2CI)2 1455sh, 1340s, 1226m, l178sh, 1140s, 1050s,870s, 755s, 728sh
been reinvestigated (Table 2). Some of the bands previously reported for NH(SO2CI)2 were due to impurities formed by reaction with sodium chloride plates [2]. Therefore, silver chloride optics were used, which are inert to the acid. The IR spectra of the alkali metal salts of imidohis(sulphuryl chloride), MN(SO2CI)e where M= Li, Na, K and Rb, are also included in Table 2. The acid shows a strong band with a maxima centred at 3200 cm-' characteristic of vN-.. The broad nature of the band may be attributed to the strong intermolecular hydrogen bonding in the pure acid. A number of weak to medium intensity bands between 2900-2500 cm-' typical of-NHe + stretching modes[12] are also observed. These ionic species are clue to the self-ionization of the acid and are probably part of the hydrogen bonded network. The spectrum of the anion, [N(SOeCI)2]- should be comparable with the isoelectronic pyrosulphuryl chloride, $2OsC12[13].However, the spectrum of anion (A) is much more complex (Table 2), and contains several additional bands. This increased
74000-400cm-' AgO plates and 400-200cm-' polythene plates. ~;4000--650cm-z NaCIplates. Table 3. Conductance measurements of imidobis(sulphuryl chloride) in pure acetic acid Run A
C X 102 (mole1-1)
X/C x 102
Ac
0.05 0.12 0.18
2.2 3.5 4.2
1.85 1.30 1.00
0.29 0.56 0.66
5.4 7.5
0.75 0.53 0.50
0.79 0.86
8.1 8.9 9.3
0.08
2.9
1.60
0.21 0.44 0.61 0.74
4.6 6.6 %8 8.6
0.88 0.61 0.52 0.49
0.48 0.47
and 6.7 kcal mole -I respectively. The values for E,~ and E,, are quite close and this is usually taken to imply that ionic migration is viscosity controlled [ l l]. The Stokes law is obeyed, i.e. the mobility of the ions is inversely proportional to the viscosity of the medium. The IR spectrum of imidobis(sulphuryl chloride) has
(A)
(B)
complexity may be attributed to increased sulphurnitrogen bond order, greater than one as envisaged by the resonance structure B. The bands at 1412 and 1202cm-~ may be assigned to V,,yr~and V,ym(S=O) stretching modes respectively. These bands are observed at lower wave numbers compared to the values for NH(SO2F)2[14]. This may be explained in terms of the low electronegativity of the chloro groups. The presence of a strong band at 972 cm-~ may be assigned.to VS-N.The assignment of the bands due to S--CI bond, which may be present below 600 cm-~ is difficult due to S-N-S bending modes in this region. However, the band at 420 cm -~ may tentatively be assigned to ~s-o as this band is consistently present in several polysulphuryl chlorides [13]. The proton NMR spectrum of imidobis (sulphuryl chloride) as liquid and as 20% (v/v) solution in CCh exhibits a sharp peak at -9.96 p.p.m. The low chemical shift value suggests that imidobis(sulphuryl chloride) is a fairly strong acid. The acid strength of imidobis(sulphuryi chloride) relative to other strong protonic acids was studied by examining conductometrically solutions of this acid in acetic acid (Table 3). Figure 1 compares the equivalent conductivity of HN(SO2CI)2with those of other strong acids[6, 15, 16]. From the position of the various
Chemistry of imidobis(sulphurylchloride)--IV
2007
2.2 2.1 2.0
1.9 A, H S O 3 F
i-0 B ~ HCIO 4
1.7
C, 1.6
HN (,S0201)2
o ,~C%~2POO-
1.5
E~ HSr 1'4
F~ HSO3CI t,3
G, H2SO4 1'2'
H~ HCI
t l.l' U .9 .8
.7 -6 .5 ,,4,
:~'---o.....o_ D
"3"
-'----o----.o-
o-G
0
i
2
3
4
5
6
~
9
10 J~ x Io2--',-
fl
t2
,3 i~,
Fig. 1. Equivalentconductivitiesof protonic acids in acetic acid.
Table 4. Freezing point depression (0) produced by some non-electrolytes Compound
Concentration(mx 102)
0 (°C)
CC14
2.46 5.07 7.92 10.33 15.13
0.42 0.86 1.35 1.77 2.59
C6H6
2.12 5.80 8.58 11.23 13.01
0.36 0.99 1.47 1.92 2.22
POCI3
3.75 7.24 9.21 13.88
0.64 1.24 1.57 2.37
curves it is evident that imidobis(suiphuryl chloride) is a stronger acid than HBr, HSOsCI and (CFs)2POOH.
Freezing point and the cryoscopic constant, Kf A large number of freezing point measurements of different samples of pure imidobis(sulphuryl chloride) have been made. The maximum freezing point of 33.40* has been observed for the pure acid which is highly sensitive to traces of impurity. Brief exposure to moisture results in a significant depression due to decomposition to give HCI, H2SO4 and H2NSO3H. The corresponding change in the specific conductivity of the acid is not so marked as the decomposition products are only weakly ionized in imidobis(sulphuryl chloride). This has been confirmed by measuring the change in the conductivity of the pure acid on addition of these solutes. It is, therefore, felt that the most sensitive test of the purity of the acid is its freezing point, although a rough guideline can also be obtained from conductivity measurements. As the heat of fusion of imidobis(sulphuryl chloride) is not known, it is necessary to find the cryoscopic constant by measuring the freezing point depression produced by some non-electrolytes. C6I-I6, CC14, POCI3, SO2C12, CrHsNO~ and Cd-I4(NO2)2 are all soluble in imidobis(suiphuryi chloride) and behave as non-electrolytes as they do not change the conductivity of the solvent. The
2008
RAM CHAND PAUL et al.
-O--O-O- C6H6
2.5
/ / ~
POCl 3
.
~
2-0
t 1"5 oO © I'O
0.5'
;~
4.
6
e, 102. m
=0
12
14
16
Fig. 2. Freezing point depression (0) produced by some non-electrolytes. results of cryoscopic measurements on C6H6, CC!4 and POC13 are given in Table 4. The experimental points for these solutes lie on a straight line upto ca. 0.15 m (Fig. 2). The slope of the curve gives a value for the cryoscopic constant, K¢, 17.2-+0.1 deg mole -t kg. REFERENCES 1. M. Becke-Goehringand E. Fluck, lnorg. Syn. 8, 105 (1966). 2. R. C. Paul, P. Kapoor, R. Kapoor and R. D. Verma, Ind. J. Chem. 13, 619 (1975). 3. R. C. Paul, P. Kapoor, R. Kapoor and R. D. Verma, Ind. J. Chem. 13, 1184(1975). 4. R. C. Paul, P. Kapoor, R. Kapoor and R. D. Verma, J. Inorg. NucL Chem. 39, 441 (1977). 5. R. C. Paul, P. Kapoor, R. Kapoor and R. D. Verma, J. Inorg. Nucl. Chem. communicated.
6. I. M. Kolthoff and A. Willman, J. Am. Chem. Soc. 56, 1007 (1934). 7. G. Jones and B. C. Bradshaw, J. Am. Chem. Soc. $5, 1780 (1933). 8. R. J. Gillespie, E. D. Hughes and C. K. Ingold, J. Chem. Soc. 2473 (1950). 9. W. J. Geary, Coord. Chem. Rev. 7, 81 (1971). 10. R. D. Feltham and R. G. Hayter, J. Chem. Soc. 4587 (1964). 11. N. N. Greenwood and R. L. Martin, J. Chem. Soc. 1427(1953). 12. L..J. Bellamy, The Infrared Spectra o[ Complex Molecules. Methuen, London (1966). 13. Von A. Simonand R. Lehmann, Z. Anorg. AUg. Chem. 311,212 (1%1). 14. J. K. Ruff, Inorg. Chem. 4, 1446(1965). 15. H.J. Emeleus, R. N. Haszeldine and R. C. Paul, J. Chem. Soc. 563 (1955). 16. R. C. Paul, S. K. Vasisht, K. C. Malhotra and S. S. Pahil, Anal. Chem. 34, 820 (1%2).
0022-1902/78/1201-2005/$02.0010
© PergamonPress Ltd.. 1978. Printed in Great Britain
CHEMISTRY OF IMIDOBIS(SULPHURYL CHLORIDE)--IV MEASUREMENTS OF PHYSICAL PROPERTIES OF IMII)OBIS(SULPHURYL CHLORIDE) RAM CHAND PAUL, PRATIBHA KAPOOR, RAMESH KAPOOR and RAJENDER DEV VERMA Department of Chemistry, Panjab University, Chandigarh-160014,India (Received 28 November 1977; received for publication 1 July 1978)
Abstract--Density, viscosity and specific conductance have been measured at 50 interval between 25 to 500 for imidobis(sulphurylchloride).The surface tension, freezing point and cryoscopicconstant have also been determined. Its IR and proton NIVlRspectra have been recorded. Relativeacidity strength measurementsin acetic acid suggestthat imidobis(sulphurylchloride) is a stronger protonic acid than HBr, HSO3C1and (CF3)2POOH.
INTRODUCTION Although imidobis(sulphuryl chloride) was synthesized in 196611] little interest has been shown in its solvent properties. The only known physical properties are its melting and boiling points and the refractive index. We have extended our earlier investigations[2-5] of this solvent.
RESULTS AND DISCUSSION Imidobis(sulphuryl chloride) is a stable, colourless, crystalline solid at room temperature. It is highly sensitive to moisture and decomposes on exposure to moist air. It can, however, be stored for longer periods, if kept in a frozen state in an air tight vessel. It is soluble in several organic solvents, viz. CCL, CHCI3, CH2C12, C6I-I6, C6HsNO2, CH3NO2, CH3CN and SO2C12. It dissolves in EXPERIMENTAL diethylether, tetrahydrofuran, acetone and methanol with lmidobis(sulphuryl chloride) was prepared by the published exothermic reaction. It is insoluble in petroleum ether, method[l]. It was purified by 2 to 3 fractional crystallizations. n-hexane and cyclohexane. The molar conductance values Acetic acid (AnalaR) was purified by a published method[6]. The purified acid had a specific conductance of less than 0.5 x of its millimolar solutions in nitrobenzene and acetonitrile 10-Tfl-)cm -'. Analytical grade CCh, C t H t , CtHsNO2 and are 30 and 130 ~ - t cm 2 mole-~ respectively. The values lie C6I'14(NO2)2were purified by the standard methods. POCI3 and well within the range expected for 1 : 1 electrolytes in these SO2CI2 were fractionally distilled and the fractions distilling at solvents[9]. Its 1 : I electrolytic nature in CH3NO2 has been 104-105" and 68-69* respectively were collected. Preparation of confirmed from a value of 210 for the slope of the straight alkali metal salts, MN(SO2CI)2,where M = Li, Na, K and Rb has line obtained by drawing a plot of Ao- Ac against ~/C [ 10]. been reported earlier[4]. The cryoscopic molecular weight determinations in nitroConductivity measurementswere carried out on a ToshniwalCI benzene (ca. 1.5% wlw solution) gave a mean value of 212. 01/01 conductivity bridge. The cell constant (0.20era-t) of a dip Its density, viscosity, surface tension and conductance type cell was determined by the standard metbod[7] and was have been measured at different temperatures and the periodically checked. Measurements were made in an oil bath thermostat which could be adjusted to any desired temperature and values are given in Table 1. The high boiling point, long maintainedto an accuracy of -+0.05*.Measurementscould be made liquid range and high viscosity suggest that, like suiphuric at temperatures below the freezing point of the pure solvent ca. 25 acid, imidobis(sulphuryl chloride) is a highly associated to 30"C, because imidobis(sulphurylchloride) supercools readily liquid and hydrogen bonding and proton transfer reactions and no problem was encountered with spontaneous crystallization will be important in this medium. Its density varies linearly of the solvent during the measurements. with temperature (*C) and its viscosity decreases markedly The cryoscope was a double walled sealed vessel having a with temperature. The plot of log ~ against I/T is a straight single-arm magnetic stirrer[8]. Temperatures were measured to line between the temperatures 308 to 3230K. This implies -+0.005*with a calibrated Beckmannthermometer. The cryoscope was immersedin a thermostat whichwas kept at ca. 1.0-+0.2° below that there is no structural break down between these the freezing point of the solution in the cryoscope. In order to temperatures. The activation energy of viscous flow has measure the freezing point, the solution was first melted and then been computed using the relation allowed to cool by placing it in the thermostat. When it had supercooled by about 0.5-1°, crystallization was induced by d log 77= slope = EJ2.303R increasingthe rate of stirring.The temperature of the solutionthen d(1/T) rose rapidly and reached a maximum value where it remained constant for several minutes. The steady maximum temperature and has been found to be 7.0 kcal mole -t. The high value of was taken as the freezing point. The density was measured by means of a bicapillarypycnometer its self-conductance suggests that imidobis(sulphuryl which was calibrated with mercury at different temperatures. The chloride) is a fairly dissociated acid and the following viscosity was measured with the help of a Ubbelohde type self-ionization may occur. viscometer.The surface tension was determined by usingTraube's Stalagmometer and the drop pipette method. 2HN(SO2C1)2 ~ [H2N(SO2CI)2]+ + [N(SO2C1)2]-. The IR spectrum of the acid was recorded in silver chloride and (1) polythene plates as liquid with a Perkin-Elmer Model 621 grating spectrophotometer. The spectra of the alkali metal salts of imidobis(sulphurylchloride) were recorded as Nujol mullson sodium The computed values of the molar conductivity (/z = K x chloride plates. The proton NMR spectrum of imidobis(sulphuryl VM) are given in Table 1. Treatment of the conductivity chloride) was recorded on a Varian A-(d)spectrometeras liquidand data by the method used for the viscosity gives values for as 20% (v/v) solution in CCI¢using TMS as the external standard. Ex and E~, (activation energies of ionic mobilities) as 6.6
2005
RAM CHAND PAUL et al.
2006
Table 1. Density, viscosity, surface tension and conductivity of imidobis(sulphuryl chloride) between 25 and 50°C Temperature (°C) Property Density (g cm-3) Viscosity (cP) Sp. cond.x 10~ (fl-' cm -I) Molar cond.x 105 (1),-'cm 2 mole-')
25
30
35
40
1.8663 --
1.8596 --
1.8528 13.3323
1.8465 10.9216
1.8397 9.1949
1.8331 7.7506
0.480
0.576
0.693
0.814
0.960
1.131
111.70
132.00
55.04
66.30
80.04
45
94.36
50
39.97
Surface tension (dynes/cm)
Table 2. 1R frequencies (cm-~) of imidobis(sulphuryl chloride)? and its alkali metal salts~: HN(SO2CI)2 3200sb, 2940w, 2860shw, 2750m,2650mb, 1665wb, 1412s, 1300s, 1202s, 1165s,972s, 870s b, 815sh, 600s b, 500s, 420w, 360m, 325w,280w LiN(SO2CI)2 1600w, 1430m,1260w, l130s, 1050m,710m,650m NaN(S02CI)2 1400sh, 1340s, 1260w, l150s, 1070s,920w, 900w, 865m, 815w, 770s, 728w KN(SO2Cl)2 1430m, 1315sh, 1280s, 1168s, 1065s, 1000s,880m, 850s, 690w RbN(SO2CI)2 1455sh, 1340s, 1226m, l178sh, 1140s, 1050s,870s, 755s, 728sh
been reinvestigated (Table 2). Some of the bands previously reported for NH(SO2CI)2 were due to impurities formed by reaction with sodium chloride plates [2]. Therefore, silver chloride optics were used, which are inert to the acid. The IR spectra of the alkali metal salts of imidohis(sulphuryl chloride), MN(SO2CI)e where M= Li, Na, K and Rb, are also included in Table 2. The acid shows a strong band with a maxima centred at 3200 cm-' characteristic of vN-.. The broad nature of the band may be attributed to the strong intermolecular hydrogen bonding in the pure acid. A number of weak to medium intensity bands between 2900-2500 cm-' typical of-NHe + stretching modes[12] are also observed. These ionic species are clue to the self-ionization of the acid and are probably part of the hydrogen bonded network. The spectrum of the anion, [N(SOeCI)2]- should be comparable with the isoelectronic pyrosulphuryl chloride, $2OsC12[13].However, the spectrum of anion (A) is much more complex (Table 2), and contains several additional bands. This increased
74000-400cm-' AgO plates and 400-200cm-' polythene plates. ~;4000--650cm-z NaCIplates. Table 3. Conductance measurements of imidobis(sulphuryl chloride) in pure acetic acid Run A
C X 102 (mole1-1)
X/C x 102
Ac
0.05 0.12 0.18
2.2 3.5 4.2
1.85 1.30 1.00
0.29 0.56 0.66
5.4 7.5
0.75 0.53 0.50
0.79 0.86
8.1 8.9 9.3
0.08
2.9
1.60
0.21 0.44 0.61 0.74
4.6 6.6 %8 8.6
0.88 0.61 0.52 0.49
0.48 0.47
and 6.7 kcal mole -I respectively. The values for E,~ and E,, are quite close and this is usually taken to imply that ionic migration is viscosity controlled [ l l]. The Stokes law is obeyed, i.e. the mobility of the ions is inversely proportional to the viscosity of the medium. The IR spectrum of imidobis(sulphuryl chloride) has
(A)
(B)
complexity may be attributed to increased sulphurnitrogen bond order, greater than one as envisaged by the resonance structure B. The bands at 1412 and 1202cm-~ may be assigned to V,,yr~and V,ym(S=O) stretching modes respectively. These bands are observed at lower wave numbers compared to the values for NH(SO2F)2[14]. This may be explained in terms of the low electronegativity of the chloro groups. The presence of a strong band at 972 cm-~ may be assigned.to VS-N.The assignment of the bands due to S--CI bond, which may be present below 600 cm-~ is difficult due to S-N-S bending modes in this region. However, the band at 420 cm -~ may tentatively be assigned to ~s-o as this band is consistently present in several polysulphuryl chlorides [13]. The proton NMR spectrum of imidobis (sulphuryl chloride) as liquid and as 20% (v/v) solution in CCh exhibits a sharp peak at -9.96 p.p.m. The low chemical shift value suggests that imidobis(sulphuryl chloride) is a fairly strong acid. The acid strength of imidobis(sulphuryi chloride) relative to other strong protonic acids was studied by examining conductometrically solutions of this acid in acetic acid (Table 3). Figure 1 compares the equivalent conductivity of HN(SO2CI)2with those of other strong acids[6, 15, 16]. From the position of the various
Chemistry of imidobis(sulphurylchloride)--IV
2007
2.2 2.1 2.0
1.9 A, H S O 3 F
i-0 B ~ HCIO 4
1.7
C, 1.6
HN (,S0201)2
o ,~C%~2POO-
1.5
E~ HSr 1'4
F~ HSO3CI t,3
G, H2SO4 1'2'
H~ HCI
t l.l' U .9 .8
.7 -6 .5 ,,4,
:~'---o.....o_ D
"3"
-'----o----.o-
o-G
0
i
2
3
4
5
6
~
9
10 J~ x Io2--',-
fl
t2
,3 i~,
Fig. 1. Equivalentconductivitiesof protonic acids in acetic acid.
Table 4. Freezing point depression (0) produced by some non-electrolytes Compound
Concentration(mx 102)
0 (°C)
CC14
2.46 5.07 7.92 10.33 15.13
0.42 0.86 1.35 1.77 2.59
C6H6
2.12 5.80 8.58 11.23 13.01
0.36 0.99 1.47 1.92 2.22
POCI3
3.75 7.24 9.21 13.88
0.64 1.24 1.57 2.37
curves it is evident that imidobis(suiphuryl chloride) is a stronger acid than HBr, HSOsCI and (CFs)2POOH.
Freezing point and the cryoscopic constant, Kf A large number of freezing point measurements of different samples of pure imidobis(sulphuryl chloride) have been made. The maximum freezing point of 33.40* has been observed for the pure acid which is highly sensitive to traces of impurity. Brief exposure to moisture results in a significant depression due to decomposition to give HCI, H2SO4 and H2NSO3H. The corresponding change in the specific conductivity of the acid is not so marked as the decomposition products are only weakly ionized in imidobis(sulphuryl chloride). This has been confirmed by measuring the change in the conductivity of the pure acid on addition of these solutes. It is, therefore, felt that the most sensitive test of the purity of the acid is its freezing point, although a rough guideline can also be obtained from conductivity measurements. As the heat of fusion of imidobis(sulphuryl chloride) is not known, it is necessary to find the cryoscopic constant by measuring the freezing point depression produced by some non-electrolytes. C6I-I6, CC14, POCI3, SO2C12, CrHsNO~ and Cd-I4(NO2)2 are all soluble in imidobis(suiphuryi chloride) and behave as non-electrolytes as they do not change the conductivity of the solvent. The
2008
RAM CHAND PAUL et al.
-O--O-O- C6H6
2.5
/ / ~
POCl 3
.
~
2-0
t 1"5 oO © I'O
0.5'
;~
4.
6
e, 102. m
=0
12
14
16
Fig. 2. Freezing point depression (0) produced by some non-electrolytes. results of cryoscopic measurements on C6H6, CC!4 and POC13 are given in Table 4. The experimental points for these solutes lie on a straight line upto ca. 0.15 m (Fig. 2). The slope of the curve gives a value for the cryoscopic constant, K¢, 17.2-+0.1 deg mole -t kg. REFERENCES 1. M. Becke-Goehringand E. Fluck, lnorg. Syn. 8, 105 (1966). 2. R. C. Paul, P. Kapoor, R. Kapoor and R. D. Verma, Ind. J. Chem. 13, 619 (1975). 3. R. C. Paul, P. Kapoor, R. Kapoor and R. D. Verma, Ind. J. Chem. 13, 1184(1975). 4. R. C. Paul, P. Kapoor, R. Kapoor and R. D. Verma, J. Inorg. NucL Chem. 39, 441 (1977). 5. R. C. Paul, P. Kapoor, R. Kapoor and R. D. Verma, J. Inorg. Nucl. Chem. communicated.
6. I. M. Kolthoff and A. Willman, J. Am. Chem. Soc. 56, 1007 (1934). 7. G. Jones and B. C. Bradshaw, J. Am. Chem. Soc. $5, 1780 (1933). 8. R. J. Gillespie, E. D. Hughes and C. K. Ingold, J. Chem. Soc. 2473 (1950). 9. W. J. Geary, Coord. Chem. Rev. 7, 81 (1971). 10. R. D. Feltham and R. G. Hayter, J. Chem. Soc. 4587 (1964). 11. N. N. Greenwood and R. L. Martin, J. Chem. Soc. 1427(1953). 12. L..J. Bellamy, The Infrared Spectra o[ Complex Molecules. Methuen, London (1966). 13. Von A. Simonand R. Lehmann, Z. Anorg. AUg. Chem. 311,212 (1%1). 14. J. K. Ruff, Inorg. Chem. 4, 1446(1965). 15. H.J. Emeleus, R. N. Haszeldine and R. C. Paul, J. Chem. Soc. 563 (1955). 16. R. C. Paul, S. K. Vasisht, K. C. Malhotra and S. S. Pahil, Anal. Chem. 34, 820 (1%2).