Construction of Larger Molecular Aluminophosphate Cages from the Cyclic Four-Ring Building Unit

New molecular aluminophosphates of different nuclearity are synthesized by a stepwise process and structurally characterized. The alkane elimination reaction of bis(trimethylsiloxy)phosphoric acid, OP(OH)(OSiMe3)2, with trialkylalanes, AlR3 (R = Me, Et, iBu), provides the cyclic dimeric aluminophosphates, [(AlR2{μ2-O2P(OSiMe3)2})2] (R = Me (1), Et (2), iBu (3)). Unsymmetrically substituted cyclic aluminophosphonate [(AlMe2{μ2-O2P(OSiMe3)(cHex)})2] (cis/trans-4) is prepared by dealkylsilylation reaction of cHexP(O)(OSiMe3)2 with AlMe3. Molecules 1–4 containing the [Al2(μ2-O2P)2] inorganic core are structural and spectroscopic models for the single four-ring (S4R) secondary building units (SBU) of zeolite frameworks. Compound 1 serves as a starting point in construction of larger molecular units by reactions with OP(OH)(OSiMe3)2 as a cage-extending reagent and with diketones, such as Hhfacac (1,1,1,5,5,5-hexafluoropentan-2,4-dione) and Hacac (pentan-2,4-dione), as capping reagents. Reaction of 1 with 4 equi...