The First Aluminophosphonate Cluster Analogue of the 4=1 SBU of Zeolites: Structure and Multinuclear Solid-State NMR Study, Including 1H NMR

Abstract

The first Al−O−P analogue of the so-called 4=1 Secondary Building Unit (SBU) of zeolites is presented and characterized by single-crystal X ray diffraction (compound 1). The 4=1 building unit structure is very rarely encountered in zeolites and microporous materials. Compound 1 was carefully studied by 31P and 27Al solid-state MAS NMR, resulting in the precise spectroscopic description of the phosphorus and aluminium sites. Unusual 27Al quadrupolar parameters were measured. Moreover, we also present a high-resolution solid-state 1H NMR study of 1 at 600 MHz and 33 kHz MAS; a remarkable improvement in resolution is observed, allowing definite assignments. The new opportunities offered by very high speed 1H NMR at high field were further demonstrated with the study of a cubane-shaped Al−O−P cluster (compound 2) and of phenylphosphonic acid. (© Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)