Grafting of peralkylated LnIIAlIII heterobimetallic complexes onto periodic mesoporous silica KIT-6Electronic supplementary information (ESI) available: DRIFT spectra showing the region 4000-400 cm−1 (Figure S1) and VT NMR spectra (50 - −90 °C) of ytterbium complex 2b (Figure S2). CCDC reference numbers 764148-764150. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c002734k
Tetraethylaluminates of the divalent lanthanides ytterbium and samarium were grafted onto large-pore cubic periodic mesoporous silica (PMS) KIT-6, which had been dehydroxylated at 500 °C (specific surface area a s : 500 m 2 g −1 ; mesopore volume V p : 1.06 cm 3 g −1 ; main pore diameter: 85 Å). The...
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| Main Authors | , , , , , , |
|---|---|
| Format | Journal Article |
| Language | English |
| Published |
31.08.2010
|
| Online Access | Get full text |
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| Summary: | Tetraethylaluminates of the divalent lanthanides ytterbium and samarium were grafted onto large-pore cubic periodic mesoporous silica (PMS) KIT-6, which had been dehydroxylated at 500 °C (specific surface area
a
s
: 500 m
2
g
−1
; mesopore volume
V
p
: 1.06 cm
3
g
−1
; main pore diameter: 85 Å). The bimetallic materials [Ln(AlEt
4
)
2
]@KIT-6
−500
were analysed by DRIFT spectroscopy, elemental analysis, nitrogen physisorption and solid-state NMR. Upon heterogenization the surface area and pore volume of the KIT-6 materials dropped by 30-35% and 25%, respectively. The hybrid materials were compared to AlEt
3
@KIT-6
−500
since reaction of AlEt
3
with surface silanol groups is also a prominent reaction pathway when complexes [Ln(AlEt
4
)
2
]
n
are immobilized. Reaction of the Ln(
ii
) tetraalkylaluminates with tris(
tert
-butoxy)silanol HOSi(O
t
Bu)
3
gave complexes Ln[(μ-OSi(O
t
Bu)
3
)(μ-R)AlR
2
]
2
(Ln = Yb, Sm; R = Et; Ln = Yb; R = Me) which can be seen as molecular model complexes, evidencing alkane elimination, trialkylaluminium adduct formation, and Ln(
ii
)-O(siloxane) bonding.
Solution grafting of perethylated complexes [Ln(AlEt
4
)
2
]
n
(Sm, Yb) onto highly dehydroxylated silica KIT-6 gives ready access to divalent rare-earth metal ethyl surface species. In contrast, such divalent tetraalkylaluminates react with HOSi(O
t
Bu)
3
to give the homoleptic siloxide complexes Ln[(μ-OSi(O
t
Bu)
3
)(μ-Et)AlEt
2
]
2
. |
|---|---|
| Bibliography: | 2b 1 For ESI and crystallographic data in CIF or other electronic format see DOI (Figure S2). CCDC reference numbers 10.1039/c002734k (Figure S1) and VT NMR spectra (50 - −90 °C) of ytterbium complex Electronic supplementary information (ESI) available: DRIFT spectra showing the region 4000-400 cm 764148-764150 |
| ISSN: | 1477-9226 1477-9234 |
| DOI: | 10.1039/c002734k |