Organoamino phosphonium cations of formula [P(NHR) 4 ] þ offer four hydrogen bonding sites that are arranged in tetrahedral fashion around the central phosphorus atom. This arrangement generates novel supramolecular building blocks that are distinct from the commonly planar NH donor systems, such as urea and guanidine. The supramolecular aggregation of these cations in the presence of chloride and several carboxylate anions is described. The carboxylate salts are obtained either by anion exchange reactions with phosphonium chlorides or by protonation reaction of the neutral phosphine imine P(NPh)-(NHPh) 3 . X-ray structure analyses of the title compounds show that they form hierarchical structures ranging from 1D chains to 2D sheets and 3D networks. Control over the dimensionality of the supramolecular structure can be achieved by modulating the steric bulk of the phosphonium cation.
Layers. -The new compounds (III), (VI), and (VIII) are hydrothermally prepared (35-60% yield) and characterized by single crystal XRD. (IIIa) crystallizes in the monoclinic space group C2/c with Z = 8 and (IIIb) and (VIb) in the monoclinic space group P21/c with Z = 2. For (VIa) two polymorphs are obtained which crystallize in the monoclinic space group C2/c with Z = 8 and in the triclinic space group P1 with Z = 1, respectively. (VIII) has a triclinic structure (P1, Z = 2). The compounds contain positively charged two-dimensional inorganic mixed-metal oxide layers which are charge-balanced by pillaring organic dianions. The triclinic polymorph of (VIa) contains a unique dimeric W2 anion which comprises two square-based pyramidal tungsten centers opposed to each other.
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