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Molar adducts of diphenyldichlorosilane with Schiff bases
.L inorg, nucl. Chem, Vol, 41, pp. 1409-1414
Pergamon Press Ltd., 19/9. Printed in Great Britain
MOLAR ADDUCTS OF DIPHENYLDICHLOROSILANE WITH SCHIFF BASES J. K. KOACHER, J. P. TANDON and R. C. MEHROTRAt Chemical Laboratories, University of Rajasthan, Jaipur-302004, India
(Received 6 April 1978; receivedfor publication 1 February 1979) Abstract--l:2 Molar reactions of diphenyldichiorosilane with a variety of Schiff bases C6HsCH:NC6Hs, C6HsCH: N(CH:)2OH, 0-OHC6I'LCH:NR and 0-OHC6H4CH: NR'OH [R = --C2Hs, -n-C4H9, -n-C3HT, -iso'C3H7, -o-C~H4CHa, -m-C6H4CH3, -p-C6H4CH3, -o-C6H4OCH3, -m-gH4OCH3, -p-C6H4OCH3 and R'=--(CH2):-, -(CH2)3-] have resulted in the synthesis of (C~Hs)~SiCI2(C~HsCH:NC6Hs)2, (C6H~)~SiCl~(SBH)~ and (C~HshSiC12(SBH2): type of derivatives [where SBH and SBH~ represent the monofuncfional bidentate and bifunctional tridentate Schiff base molecules, respectively]. However, bifunctional tetradentate Schiff bases (S'B'H2) having the donor system HO N N OH have been found to form 1:1 derivatives only. The molar conductance measurements in DMF show them to be non-electrolytes. INTRODUCTION In recent years reactions of tin(IV)[l] and lead (IV)[2] chloride with different type of Schiff bases have been investigated. However, no such derivatives of diphenyldichlorosilane have been reported. It was, therefore, considered of interest to study the reactions of diphenyldichlorosilan¢ with a variety of Schiff bases (I, II, III and IV).
~
C=NCH2CH20H (I)
~
t_
OH C'-NR I
(11,SBH) R = C2Hs, n-C,,Hg, n-C3Hz, iso-C3H~, o-C6H4OCH3, m-CeH4OCH3, p-CeH4OCH3, o-CeH4CH3, m-C6H4CH3, p'C6H4CH3.
ethanol. Diphenyldichlorosilane (BDH) was distilled :at lll°C/0.3mm and DMF was purified as reported earlier|3]. Molecular weights were determined ebollioscopically in chloroform or methanol. IR spectra were recorded in the form of KBr pellets on a Perkin-Elmer grating spectrophotometer (model 337) in the range of 4000-400cm -~. Preparation of Schiff bases. Schiff bases were prepared bythe condensation of aldehydes with alkyl, aryl or hydroxyalkYlamines or diamines in stoichiometric amounts in the presence of benzene, refluxing for several hours. The water formed in the reaction was then removed azeotropically with benzene. The products were distilled before use or recrystallized. Analytical methods and physical measurements. In these compounds, the following method was adopted for the estimation of silicon keeping in view the volatility and comparatively stable nature of carbon-silicon bond[4]. The compound (0.1-0.3g) was added to 30 ml sulphuric acid (AR) in 250 ml conical flask. The container was cooled and 5 gm each of solid ammonium sulphate (AR) and ammonium nitrate (AR) were added. It was then kept overnight at the room iemperature and finally digested for 4 hr. The solution was ~hen cooled and diluted with water. The precipitate so obtained was filtered, dried and ignited to give SiO2. Chlorine. Chlorine was estimated volumetrically by the Volbard's method[5]. Nitrogen. Nitrogen was estimated by Kjeldahl's method. The conductance measurements were made with Tesla RLC bridge using cell having cell constant of 0.09313 cm-~ at 30 ± I°C.
Synthesis of silicon complexes of Schi~ bases derived from salicylaldehyde. Reactions of diphenyldichlorosilane with Schiff bases in 1:2 and 1:1 molar ratios have been carded out. The calculated amount of the Schiff base was slowly added tO the benzene solution of (C6H5)2SiC12 with constant shaking. An exothermic reaction took place and the solid compound separated immediately. After decanting off the solventi the resulting solids were repeatedly washed with dry benzenei The remaining solvent was removed in vacuo and the products were finally dried at 40-60°C/0.5 nun for 3-4 hr. The physical as well as chemical properties of these complexes have been given in Tables 1-3.
R'= (CH2)2, (CH2)~ -'NR' OH
H
(111, SBH=)
X = (CH2)2, (CH2)~
I
I
H
RESULTS AND DISCUSSION In general, reactions of diphenyldichlorosilane with the different type of Schiff bases may be represented as follows:
H
(IV, S'B'H~) EXPERIMENTAL All the reactions were carried out in quickfit apparatus under strictly anhydrous conditions. Benzene (BDH) was first kept over sodium wire, then distilled and finally dried azeotropically with
tVice-Chancellor, University of Delhi, Delhi.
(C6H5)2SICI2 + 2Cd-I~CH: NC61-I5 (C6Hs)2SiCI2(C6H~CH: NC6Hs)2 (C6H5)2SiCl2 + (C6I'[5)2SiCl2 +
1409
2SBH 2SBH2
~ (CsHs)2SiCI2"2SBH ~ (Cdts)2SiCI2"2SBH2
J . K . KOACHER et al.
1410
0
e4~
0
o7
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ele, i
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:~
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q
~2
°.
Z~ d
o.
z 0
u °~
I=
g.
Molar adducts
.~.,q
•
•, / ~
of diphenyldichlorosilane
with Schiff bases
°
~+
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eq,.,q
ed
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~
,,/+
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~,,-;
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=.,=.
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",,.-~ - . o ;~ "~
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. --.~
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Z¢.. '~
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,~
r-:
od
~
o
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e,i
1411
1412
J.K. KOACHER et al.
~°~ 8.~o o
°~
~7 .-$
o
¢*q .°
~r~
~d
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v
g
g t~ r~
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o o
..
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8
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o
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G
o
r~
r~
e.i
~Z
e4
Molar adducts of diphenyldichlorosilanewith Schiffbases (Where SBH and SBH2 represent the monofunctional bidentate and bifunctional tridentate Schift bases respectively). The formation of only 1 : 2 molar adducts indicates that the alcoholic or phenolic proton does not take part in these reactions and the Schiff bases simply act as neutral monodentate ligands with the nitrogen of azomethine group coordinating to silicon. Further, all these derivatives have been found to be monomeric in boiling chloroform or methanol. The complexes contain six coordinate silicon but the configurations have not been determined. These reactions were also attempted in 1:1 molar ratio; but the analyses of the resulting products were found to correspond to 1 : 2 type derivatives only. The bifunctional tetradentate Schiff bases have been found to form 1:1 adducts with diphenyldichlorosilane, presumably with the two donating nitrogen atoms of the Shifts bases occupying cis positions at the silicon. The molar conductance values in DMF for these derivatives as determined at 10-3M concentration (30_+ I°C) fall in the range of 50-70 fl-' cm2 tool-~ (Tables 1, 2 and 3) suggesting they are poor electrolytes. IR spectra. A strong band at -1625_+5cm -~ is observed in the IR spectra of the Schiff bases and this may be assigned to uC=N. The coordination of azomethine nitrogen to silicon atom is indicated by the shift of vC=N band to higher frequency. However, in the complexes of silicon with monofunctional bidentate and bifunctional tri- and tetradentate Schiff bases, the above
1413
band appears at -1640cm -I and 1655_+5cm-~ respectively. Birader and Kulkarni [6, 7] made similar observations in the Sn(IV) complexes. The strong band appearing around 1280cm -~ in the spectra of the ligands due to phenolic C-O stretching vibration[8,9] remains almost unaltered, thus indicating the phenolic oxygen is not coordinated in these derivatives. In the spectra of bifunctional tridentate ligands a broad and medium band in the 3500-3300cm-I region is observed due to the hydrogen bonded OH. This is unperturbed in the complexes showing that the alcoholic or phenolic group of the ligands does not take part in the complexation reactions. NMR spectra Proton magnetic resonance spectra of p-tolylsalieylideneamine and its 1 : 2 derivative have been recorded in CDCI3 using tetramethyisilane as the internal standard. On comparison of the two spectra, the following points appear to be significant (Table 4): 1. The phenolic proton signal observed at 12.75~ in the spectra of the ligand remains unchanged in the spectra of its derivative, thereby indicating that the phenolic group does not take part in complexation. 2. The methyl proton signals shift down field in the spectra of the derivative. This may be due to the coordination of the silicon to the nitrogen through a dative bond causing a change in the electronic environment of these protons.
Table 4. The chemical shift value (3) of the proton in the proton magnetic resonance spectra of the Schiff base and its derivative with respect to tetramethyl silane (TMS)
Compound
Azomethine proton ----C=N I H
Aromatic proton
Phenolic proton --OH
--CH3
8.52
7.12
12.75
2.28
8.60
8.20
12.75
2.40
OH
C--H
C6H5 i ' ~
cHz
H3C_~l~CsHs @°"
H~C
JINC Vol. 41, No. IO---B
1414
J.K. KOACHER et al.
3. The methine proton signal at 8.528 in the spectra of the ligand shifts to 8.608 in the complexes, this further supports the coordination of silicon to the nitrogen of the azomethine group, Acknowledgement--One of the authors (J.K.K.) is grateful to the U.G.C. for the financial assistance under the Special Ass/stance Programme. REFERENCES I. T. hl. Shrivastava and A. K. S. Chauhan, Inorg Nucl. Chem. Lett. 4, 389 (1968).
2. A. Singh, Ph.D. Thesis, Rajasthan University, laipur (India) (1972). 3. O. P. Singh, R. N. Prasad and J. P. Tandon, Z. Naturforsch, 30b, 46 (1975). 4. R. C. Mehrotra and P. Bajaj, J. Organometal. Chem. 22, 41 (1970). 5. I. Vogel, Quant. lnorg. Anal. 33, 266 (1969). 6. N. S. Birader and V. H. Kulkarni, J. lnorg. Nucl. Chem. 33, 245 (1971). 7. N. S. B/rader and V. H. Kulkarni, J. lnorg. Nucl. Chem. 33, 3847 (1971). 8. C. S. Marvel, S. A. Aspoy and A. Dudley, J. Am. Chem. $oc. 78, 4909 (1956). 9. J. E. Kovacic, Spectrochim. Acta 23(A), 183 (1967).
Pergamon Press Ltd., 19/9. Printed in Great Britain
MOLAR ADDUCTS OF DIPHENYLDICHLOROSILANE WITH SCHIFF BASES J. K. KOACHER, J. P. TANDON and R. C. MEHROTRAt Chemical Laboratories, University of Rajasthan, Jaipur-302004, India
(Received 6 April 1978; receivedfor publication 1 February 1979) Abstract--l:2 Molar reactions of diphenyldichiorosilane with a variety of Schiff bases C6HsCH:NC6Hs, C6HsCH: N(CH:)2OH, 0-OHC6I'LCH:NR and 0-OHC6H4CH: NR'OH [R = --C2Hs, -n-C4H9, -n-C3HT, -iso'C3H7, -o-C~H4CHa, -m-C6H4CH3, -p-C6H4CH3, -o-C6H4OCH3, -m-gH4OCH3, -p-C6H4OCH3 and R'=--(CH2):-, -(CH2)3-] have resulted in the synthesis of (C~Hs)~SiCI2(C~HsCH:NC6Hs)2, (C6H~)~SiCl~(SBH)~ and (C~HshSiC12(SBH2): type of derivatives [where SBH and SBH~ represent the monofuncfional bidentate and bifunctional tridentate Schiff base molecules, respectively]. However, bifunctional tetradentate Schiff bases (S'B'H2) having the donor system HO N N OH have been found to form 1:1 derivatives only. The molar conductance measurements in DMF show them to be non-electrolytes. INTRODUCTION In recent years reactions of tin(IV)[l] and lead (IV)[2] chloride with different type of Schiff bases have been investigated. However, no such derivatives of diphenyldichlorosilane have been reported. It was, therefore, considered of interest to study the reactions of diphenyldichlorosilan¢ with a variety of Schiff bases (I, II, III and IV).
~
C=NCH2CH20H (I)
~
t_
OH C'-NR I
(11,SBH) R = C2Hs, n-C,,Hg, n-C3Hz, iso-C3H~, o-C6H4OCH3, m-CeH4OCH3, p-CeH4OCH3, o-CeH4CH3, m-C6H4CH3, p'C6H4CH3.
ethanol. Diphenyldichlorosilane (BDH) was distilled :at lll°C/0.3mm and DMF was purified as reported earlier|3]. Molecular weights were determined ebollioscopically in chloroform or methanol. IR spectra were recorded in the form of KBr pellets on a Perkin-Elmer grating spectrophotometer (model 337) in the range of 4000-400cm -~. Preparation of Schiff bases. Schiff bases were prepared bythe condensation of aldehydes with alkyl, aryl or hydroxyalkYlamines or diamines in stoichiometric amounts in the presence of benzene, refluxing for several hours. The water formed in the reaction was then removed azeotropically with benzene. The products were distilled before use or recrystallized. Analytical methods and physical measurements. In these compounds, the following method was adopted for the estimation of silicon keeping in view the volatility and comparatively stable nature of carbon-silicon bond[4]. The compound (0.1-0.3g) was added to 30 ml sulphuric acid (AR) in 250 ml conical flask. The container was cooled and 5 gm each of solid ammonium sulphate (AR) and ammonium nitrate (AR) were added. It was then kept overnight at the room iemperature and finally digested for 4 hr. The solution was ~hen cooled and diluted with water. The precipitate so obtained was filtered, dried and ignited to give SiO2. Chlorine. Chlorine was estimated volumetrically by the Volbard's method[5]. Nitrogen. Nitrogen was estimated by Kjeldahl's method. The conductance measurements were made with Tesla RLC bridge using cell having cell constant of 0.09313 cm-~ at 30 ± I°C.
Synthesis of silicon complexes of Schi~ bases derived from salicylaldehyde. Reactions of diphenyldichlorosilane with Schiff bases in 1:2 and 1:1 molar ratios have been carded out. The calculated amount of the Schiff base was slowly added tO the benzene solution of (C6H5)2SiC12 with constant shaking. An exothermic reaction took place and the solid compound separated immediately. After decanting off the solventi the resulting solids were repeatedly washed with dry benzenei The remaining solvent was removed in vacuo and the products were finally dried at 40-60°C/0.5 nun for 3-4 hr. The physical as well as chemical properties of these complexes have been given in Tables 1-3.
R'= (CH2)2, (CH2)~ -'NR' OH
H
(111, SBH=)
X = (CH2)2, (CH2)~
I
I
H
RESULTS AND DISCUSSION In general, reactions of diphenyldichlorosilane with the different type of Schiff bases may be represented as follows:
H
(IV, S'B'H~) EXPERIMENTAL All the reactions were carried out in quickfit apparatus under strictly anhydrous conditions. Benzene (BDH) was first kept over sodium wire, then distilled and finally dried azeotropically with
tVice-Chancellor, University of Delhi, Delhi.
(C6H5)2SICI2 + 2Cd-I~CH: NC61-I5 (C6Hs)2SiCI2(C6H~CH: NC6Hs)2 (C6H5)2SiCl2 + (C6I'[5)2SiCl2 +
1409
2SBH 2SBH2
~ (CsHs)2SiCI2"2SBH ~ (Cdts)2SiCI2"2SBH2
J . K . KOACHER et al.
1410
0
e4~
0
o7
eq °o
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~2~2
•
o
e~
0
0 0
A
e*
e4
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,-;
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¢.q °.
Z,.a
q
~2
°.
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o.
z 0
u °~
I=
g.
Molar adducts
.~.,q
•
•, / ~
of diphenyldichlorosilane
with Schiff bases
°
~+
,4,,*
eq,.,q
ed
"
~
,,/+
"
~,,-;
G e~
=.,=.
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z~
-
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~
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od
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o
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1411
1412
J.K. KOACHER et al.
~°~ 8.~o o
°~
~7 .-$
o
¢*q .°
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~d
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v
g
g t~ r~
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o o
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o
8
¢,o
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o
eq r~
r~
F-., cj
G
o
r~
r~
e.i
~Z
e4
Molar adducts of diphenyldichlorosilanewith Schiffbases (Where SBH and SBH2 represent the monofunctional bidentate and bifunctional tridentate Schift bases respectively). The formation of only 1 : 2 molar adducts indicates that the alcoholic or phenolic proton does not take part in these reactions and the Schiff bases simply act as neutral monodentate ligands with the nitrogen of azomethine group coordinating to silicon. Further, all these derivatives have been found to be monomeric in boiling chloroform or methanol. The complexes contain six coordinate silicon but the configurations have not been determined. These reactions were also attempted in 1:1 molar ratio; but the analyses of the resulting products were found to correspond to 1 : 2 type derivatives only. The bifunctional tetradentate Schiff bases have been found to form 1:1 adducts with diphenyldichlorosilane, presumably with the two donating nitrogen atoms of the Shifts bases occupying cis positions at the silicon. The molar conductance values in DMF for these derivatives as determined at 10-3M concentration (30_+ I°C) fall in the range of 50-70 fl-' cm2 tool-~ (Tables 1, 2 and 3) suggesting they are poor electrolytes. IR spectra. A strong band at -1625_+5cm -~ is observed in the IR spectra of the Schiff bases and this may be assigned to uC=N. The coordination of azomethine nitrogen to silicon atom is indicated by the shift of vC=N band to higher frequency. However, in the complexes of silicon with monofunctional bidentate and bifunctional tri- and tetradentate Schiff bases, the above
1413
band appears at -1640cm -I and 1655_+5cm-~ respectively. Birader and Kulkarni [6, 7] made similar observations in the Sn(IV) complexes. The strong band appearing around 1280cm -~ in the spectra of the ligands due to phenolic C-O stretching vibration[8,9] remains almost unaltered, thus indicating the phenolic oxygen is not coordinated in these derivatives. In the spectra of bifunctional tridentate ligands a broad and medium band in the 3500-3300cm-I region is observed due to the hydrogen bonded OH. This is unperturbed in the complexes showing that the alcoholic or phenolic group of the ligands does not take part in the complexation reactions. NMR spectra Proton magnetic resonance spectra of p-tolylsalieylideneamine and its 1 : 2 derivative have been recorded in CDCI3 using tetramethyisilane as the internal standard. On comparison of the two spectra, the following points appear to be significant (Table 4): 1. The phenolic proton signal observed at 12.75~ in the spectra of the ligand remains unchanged in the spectra of its derivative, thereby indicating that the phenolic group does not take part in complexation. 2. The methyl proton signals shift down field in the spectra of the derivative. This may be due to the coordination of the silicon to the nitrogen through a dative bond causing a change in the electronic environment of these protons.
Table 4. The chemical shift value (3) of the proton in the proton magnetic resonance spectra of the Schiff base and its derivative with respect to tetramethyl silane (TMS)
Compound
Azomethine proton ----C=N I H
Aromatic proton
Phenolic proton --OH
--CH3
8.52
7.12
12.75
2.28
8.60
8.20
12.75
2.40
OH
C--H
C6H5 i ' ~
cHz
H3C_~l~CsHs @°"
H~C
JINC Vol. 41, No. IO---B
1414
J.K. KOACHER et al.
3. The methine proton signal at 8.528 in the spectra of the ligand shifts to 8.608 in the complexes, this further supports the coordination of silicon to the nitrogen of the azomethine group, Acknowledgement--One of the authors (J.K.K.) is grateful to the U.G.C. for the financial assistance under the Special Ass/stance Programme. REFERENCES I. T. hl. Shrivastava and A. K. S. Chauhan, Inorg Nucl. Chem. Lett. 4, 389 (1968).
2. A. Singh, Ph.D. Thesis, Rajasthan University, laipur (India) (1972). 3. O. P. Singh, R. N. Prasad and J. P. Tandon, Z. Naturforsch, 30b, 46 (1975). 4. R. C. Mehrotra and P. Bajaj, J. Organometal. Chem. 22, 41 (1970). 5. I. Vogel, Quant. lnorg. Anal. 33, 266 (1969). 6. N. S. Birader and V. H. Kulkarni, J. lnorg. Nucl. Chem. 33, 245 (1971). 7. N. S. B/rader and V. H. Kulkarni, J. lnorg. Nucl. Chem. 33, 3847 (1971). 8. C. S. Marvel, S. A. Aspoy and A. Dudley, J. Am. Chem. $oc. 78, 4909 (1956). 9. J. E. Kovacic, Spectrochim. Acta 23(A), 183 (1967).