Aluminium five-coordinated zeolites

A P- Al J-coupling constant for trimethylphosphine bound to the Lewis acid of Zeolite HY has been determined by Al to P INEPT methods,since coupling could not be resolved for this resonance (6= —49) in the P MAS NMR spectrum. The coupling was consistent with a five-coordinated aluminium Lewis acid/trimethyl phosphine complex, and thus a four-coordinated Lewis acid site. Bi- and tricyclic penta- and hexacoordinated-phosphoranes 25-28 have been... 

In Fig. 2.18 we show MAS NMR spectra of solids with different NMR nuclei some of the other possible nuclei are Na, P, Fe, Cd and Sn. In Fig. 2.19, MAS NMR spectra of aluminium-containing materials are shown to indicate how octahedral and tetrahedral coordination of AI are readily distinguished. In Fig. 2.20, Si spectra of several zeolites are shown to point out how silicon atoms coordinated differently (by aluminium atoms) exhibit widely different chemical shifts the numbers above the peaks represent n in Si(nAl) with five possible values (0 to 4). Si, AI ordering... 

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