Are the NF4+ cations in NF4BF4 really nontetrahedral?
The crystal structure of NF4BF4 has been reexamined. The low-temperature X-ray structure and solid-state 19F MAS NMR spectra are in agreement with the conclusions reached from the vibrational spectra, that solid NF4+ salts contain only tetrahedral NF4+ cations. The alleged observation of two kind of nontetrahedral NF4+ cations in several previous crystal structures is attributed to incorrectly solved structures and, possibly, problems caused by disorder or twinning. It is further evidence for the dangers of over-reliance on crystal structures. Flawed crystal structures can give rise to either bad or unwarranted theory.
Haiges
Ralf
R
Department of Chemistry and Loker Research Institute, University of Southern California, Los Angeles, California 90089-1661, USA. haiges@usc.edu
Gerken
Michael
M
Iuga
Adriana
A
Bau
Robert
R
Christe
Karl O
KO