Chemistry Reference
In-Depth Information
much upon increase of the applied magnetic field. Therefore the comparison of MQMAS
experiments at different magnetic field strength is most important for an assignment of
various species. Although the data analysis is very difficult, the presence of various signals
was revealed [40].
A 3QMAS spectrum of HS-AlF
3
is given in Figure 1.23.
70
°C, 2
h
100
°C, 2
h
--15 ppm
150
°C, 2
h
170
°C, 4
h
100
50
0
-50
-100
-150
(ppm)
Figure 1.22
27
Al MAS NMR spectra (central lines) of a AlF
2.3
OiPr
0.7
.
xiPrOH gel thermally
dried in a vacuum at different temperatures (
rot
¼ 25 kHz, B
0
¼ 9,4 T) (Reprinted with
permission from [44] Copyright (2009) Humboldt University of Berlin.)
-40
qc
cs
B'
-20
A'
0
20
40
20
0
-20
δ
MAS
(
27
Al) in ppm
-40
-60
Figure 1.23 3QMAS NMR spectrumof HS-AlF
3
acquired at 19.9 T (Reprinted with permission
from [40] Copyright (2009) American Chemical Society.)
