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New templates for the synthesis of clathrasils
H.G. Karge and J. Weitkamp (Eds.) 40
NEW
Zeolite Science 1994: Recent Progress and Discussions
Studies in Surface Science and Catalysis, Vol. 98 9 1995 Elsevier Science B.V. All rights reserved.
TEMPLATES
FOR THE
SYNTHESIS
OF CLATHRASII~S
G. van de Goor, C. Braunbarth, C.C. Freyhardt, J. Felsche and P. Behrens Fakult~t for Chemie, UniversiNt Konstanz, D-78434 Konstanz, Germany SUMMARY Three new templates for the synthesis of silica sodalites and three different clathrasil compounds synthesized with the first metal-organic template molecule are presented. INTRODUCTION The template mechanism in the synthesis of microporous solids is still not fully understood. Besides direct investigations of the crystallization process, it is worthwhile to study the action of new template molecules, which either (a) are derived from known templates by arguments of chemical and geometrical similarity, or which (b) open up new classes of (possible) template molecules. In this contribution, we illustrate point (a) by the judicious choice of templates for synthesis of silica sodalites; point (b) is exemplified by the use of a metal-organic complex as a template. In any case the host matrix is built up from pure silica, in order to simplify the synthesis system and to restrict host-template interactions to van der Waals forces. EXPERIMENTAL All syntheses were carried out in teflon-lined steel autoclaves. Typical data for the synthesis of silica sodalites are given in Table 1. As metal-organic template the cobalticinium cation [Co(C5H5)2] + =- Cocp~ was investigated in the system SiO 2 - N H 4 F - Cocp2PF 6 - H20. Three different clathrasil phases were obtained (Table 2). RESULTS AND DISCUSSION The choice of possible new templates for the synthesis of silica sodalites was guided by arguments of geometric and chemical similiarity to the known templates, namely ethylene glycol (EG) [1] and 1,3,5-trioxane (TR) [2]. The new template 1,3-dioxolane (DI) may be regarded as a hybrid structure between TR and one of the conformations of EG, which contains an intramolecular hydrogen bond and exhibits a five-membered ring structure [3]. Two further new templates for silica sodalite synthesis, namely ethanol amine (EA) and ethylene diamine (ED), are derived by step-wise substitution of the OH groups of EG by NH 2 groups. EA and ED are the first amines that direct the synthesis of silica sodalite [4]. With the Cocp~ cation as template, three different clathrasil phases with structure types nonasil (NON), octadecasil (AST) and dodecasil-lH (DOH) were obtained [5]. All exhibit the yellow colour typical of the cobalticinium cation. The formation of [Cocp~F-]-NON was also recently indicated by BALKUS & SHEPELEV [6]. The fact that also other clathrasil
41
compounds can be formed shows that templating with metal-organic molecules is a general approach for the synthesis of microporous solids. Table 1. Molar composition ratio of the synthesis mixture, crystallization conditions and yield for the synthesis of silica socialites M[SiO2]6. sodalite
SiO 2
M
Na20
H20
T (K)
time (d)
yidd
TRS-SOD
1
0.54
0.07 (Na2CO3)
8.9
443
3
95 %
DIS-SOD
1
2.55
0.20
51
423
6
86 %
EGS-SOD
1
1.60
0.05
-
443
35
90 %
EAS-SOD
1
1.25
0.025
-
443
61
90 %
EDS-SOD
1
1.25
0.025
-
443
33
88 %
Table 2: Molar composition ratio of the synthesis mixture and crystallization conditions for Cocp~-containing clathrasils. SiO 2
NH4F
[Cocp2] PF 6
H20
T (~
time (days)
product
formula
1.0
1.0
0.45
55.5
160
14-21
[Cocp~F-l-NON
[Co(C5H5)~F-I [SiO2122
5.5
5.5
0.45
55.5
170
7
ICocp~F-l-AST
[Co(C5H5)~F-I [SiOzll0
5.5
5.5
0.45
55.5
190
10
[Cocp~F-I-AST and =5% [Cocp~F-l-DOH
ICo(C5H5)~F-] [SiO2110 and [Co(C5H5)~F-] [SiO2134
[COCp~F-]-NON was characterized by a single-crystal x-ray diffraction analysis (Fig. 1) [5]. Surprisingly, the Cocp~ cation is entrapped in a well-ordered manner, with no signs of rotational or other disorder. Also of interest is the position of the F- ion compensating the charge of the Cocp~ cation: It occupies a site in one of the smaller cages of
Fig. 1. Structure of Cocp~-NON as determined by the nonasil structure and is loosely coordinated single crystal structural analysis. Note the alignment tO a Si atom of the framework (dsi_F: 1 84 ,/k) of the Cocp~ ions. The framework is indicated only 9 " by Si-Si connections. This work was supported by the DFG (Fe72/17-1, Be1664/1).
REFERENCES [1] D.M. Bibby, M.P. Dale, Nature 317 (1985) 157. J. Keijsper et al., in "Zeolites: Facts, Figures, Future", Elsevier 1989, p. 237. [2] G. van de Goor, P. Behrens, J. Felsche, Microporous Mater., in the press. [3] [4] C. Braunbarth, G. van de Goor, A.M. Schneider, J. Felsche, P. Behrens, in prep. G. van de Goor, C.C. Freyhardt, P. Behrens, subm. to Z. Anorg. Allg. Chemie. [5] [6] K.J. Balkus, S. Shepelev, Microporous Mat. 1 (1993) 383.1
NEW
Zeolite Science 1994: Recent Progress and Discussions
Studies in Surface Science and Catalysis, Vol. 98 9 1995 Elsevier Science B.V. All rights reserved.
TEMPLATES
FOR THE
SYNTHESIS
OF CLATHRASII~S
G. van de Goor, C. Braunbarth, C.C. Freyhardt, J. Felsche and P. Behrens Fakult~t for Chemie, UniversiNt Konstanz, D-78434 Konstanz, Germany SUMMARY Three new templates for the synthesis of silica sodalites and three different clathrasil compounds synthesized with the first metal-organic template molecule are presented. INTRODUCTION The template mechanism in the synthesis of microporous solids is still not fully understood. Besides direct investigations of the crystallization process, it is worthwhile to study the action of new template molecules, which either (a) are derived from known templates by arguments of chemical and geometrical similarity, or which (b) open up new classes of (possible) template molecules. In this contribution, we illustrate point (a) by the judicious choice of templates for synthesis of silica sodalites; point (b) is exemplified by the use of a metal-organic complex as a template. In any case the host matrix is built up from pure silica, in order to simplify the synthesis system and to restrict host-template interactions to van der Waals forces. EXPERIMENTAL All syntheses were carried out in teflon-lined steel autoclaves. Typical data for the synthesis of silica sodalites are given in Table 1. As metal-organic template the cobalticinium cation [Co(C5H5)2] + =- Cocp~ was investigated in the system SiO 2 - N H 4 F - Cocp2PF 6 - H20. Three different clathrasil phases were obtained (Table 2). RESULTS AND DISCUSSION The choice of possible new templates for the synthesis of silica sodalites was guided by arguments of geometric and chemical similiarity to the known templates, namely ethylene glycol (EG) [1] and 1,3,5-trioxane (TR) [2]. The new template 1,3-dioxolane (DI) may be regarded as a hybrid structure between TR and one of the conformations of EG, which contains an intramolecular hydrogen bond and exhibits a five-membered ring structure [3]. Two further new templates for silica sodalite synthesis, namely ethanol amine (EA) and ethylene diamine (ED), are derived by step-wise substitution of the OH groups of EG by NH 2 groups. EA and ED are the first amines that direct the synthesis of silica sodalite [4]. With the Cocp~ cation as template, three different clathrasil phases with structure types nonasil (NON), octadecasil (AST) and dodecasil-lH (DOH) were obtained [5]. All exhibit the yellow colour typical of the cobalticinium cation. The formation of [Cocp~F-]-NON was also recently indicated by BALKUS & SHEPELEV [6]. The fact that also other clathrasil
41
compounds can be formed shows that templating with metal-organic molecules is a general approach for the synthesis of microporous solids. Table 1. Molar composition ratio of the synthesis mixture, crystallization conditions and yield for the synthesis of silica socialites M[SiO2]6. sodalite
SiO 2
M
Na20
H20
T (K)
time (d)
yidd
TRS-SOD
1
0.54
0.07 (Na2CO3)
8.9
443
3
95 %
DIS-SOD
1
2.55
0.20
51
423
6
86 %
EGS-SOD
1
1.60
0.05
-
443
35
90 %
EAS-SOD
1
1.25
0.025
-
443
61
90 %
EDS-SOD
1
1.25
0.025
-
443
33
88 %
Table 2: Molar composition ratio of the synthesis mixture and crystallization conditions for Cocp~-containing clathrasils. SiO 2
NH4F
[Cocp2] PF 6
H20
T (~
time (days)
product
formula
1.0
1.0
0.45
55.5
160
14-21
[Cocp~F-l-NON
[Co(C5H5)~F-I [SiO2122
5.5
5.5
0.45
55.5
170
7
ICocp~F-l-AST
[Co(C5H5)~F-I [SiOzll0
5.5
5.5
0.45
55.5
190
10
[Cocp~F-I-AST and =5% [Cocp~F-l-DOH
ICo(C5H5)~F-] [SiO2110 and [Co(C5H5)~F-] [SiO2134
[COCp~F-]-NON was characterized by a single-crystal x-ray diffraction analysis (Fig. 1) [5]. Surprisingly, the Cocp~ cation is entrapped in a well-ordered manner, with no signs of rotational or other disorder. Also of interest is the position of the F- ion compensating the charge of the Cocp~ cation: It occupies a site in one of the smaller cages of
Fig. 1. Structure of Cocp~-NON as determined by the nonasil structure and is loosely coordinated single crystal structural analysis. Note the alignment tO a Si atom of the framework (dsi_F: 1 84 ,/k) of the Cocp~ ions. The framework is indicated only 9 " by Si-Si connections. This work was supported by the DFG (Fe72/17-1, Be1664/1).
REFERENCES [1] D.M. Bibby, M.P. Dale, Nature 317 (1985) 157. J. Keijsper et al., in "Zeolites: Facts, Figures, Future", Elsevier 1989, p. 237. [2] G. van de Goor, P. Behrens, J. Felsche, Microporous Mater., in the press. [3] [4] C. Braunbarth, G. van de Goor, A.M. Schneider, J. Felsche, P. Behrens, in prep. G. van de Goor, C.C. Freyhardt, P. Behrens, subm. to Z. Anorg. Allg. Chemie. [5] [6] K.J. Balkus, S. Shepelev, Microporous Mat. 1 (1993) 383.1