In the presence of NH4+ and either PPh4+ or PPh3Me+ cations, 1,3-adamantanediacetic acid (H(2)ADA) reacts with uranyl ions under solvo-hydrothermal conditions to give the complexes [NH4](2)[PPh4](2)[(UO2)(4)(ADA)(6)] (1) and {NH4}(2)[PPh3Me](2)[(UO2)(4)(ADA)(6)] (2), both of which contain a tetranuclear metallatricycle built from two 2:2 rings including convergent ligands, linked by two additional ligands in an extended conformation defining a third, larger ring. While the ammonium cations are closely associated with the 2:2 rings through triple hydrogen bonding, the large PPh4+, or PPh3Me+ cations are more loosely bound to each of the two faces of the larger ring. In contrast, the complex [H2NMe2]{PPh3Me]-[(UO2)(2)(ADA)(3)]center dot H2O (3), in which dimethylammonium replaces ammonium cations, crystallizes as a two-dimensional network with honeycomb {6(3)} topology, albeit with very distorted, elongated hexagonal cells. These and previous results show that both NH4+ and PPh4+ or PPh3Me+ cations are essential to the formation of the metallatricycle. The role of the flexibility imparted to ADA(2-) by the acetate arms, in comparison to the more rigid 1,3-adamantanedicarboxylate (ADC(2-)), is also discussed. All three complexes are luminescent, with quantum yields of 0.06, 0.06, and 0.09 for 1-3, respectively. The vibronic fine structure apparent on the emission spectra gives peak positions typical of species in which the uranyl ion is chelated by three carboxylate groups.