As you like it: [Ag(η2‐As4)2]+[pftb]− can be used to store yellow arsenic (As4). From it, As4 can be easily released to give concentrated, light‐stable solutions. These As4 solutions, and those of white phosphorus (P4), allowed molecular As4 and P4 to be encapsulated inside giant, spherical aggregates and polymeric matrices, enabling the first determination of their EE (E=P, As) bond lengths by diffraction methods.

The formation of reversible switchable nanostructures monitored by solution and solid-state methods is still a challenge in supramolecular chemistry. By a comprehensive solid state and solution study we demonstrate the potential of the fivefold symmetrical building block of pentaphosphaferrocene in combination with CuI halides to switch between spheres of different porosity and shape. With increasing amount of CuX, the structures of the formed supramolecules change from incomplete to complete spherically shaped fullerene-like assemblies possessing an Ih-C80 topology at one side and to a tetrahedral-structured aggregate at the other. In the solid state, the formed nano-sized aggregates reach an outer diameter of 3.14 and 3.56 nm, respectively. This feature is used to reversibly encapsulate and release guest molecules in solution.

Treatment of the pentaphosphaferrocene [Cp*Fe(η(5)-P(5))] with Cu(I) halides in the presence of different templates leads to novel fullerene-like spherical molecules that serve as hosts for the templates. If ferrocene is used as the template the 80-vertex ball [Cp(2)Fe]@[{Cp*Fe(η(5)-P(5))}(12){CuCl}(20)] (4), with an overall icosahedral C(80) topological symmetry, is obtained. This result shows the ability of ferrocene to compete successfully with the internal template of the reaction system [Cp*Fe(η(5)-P(5))], although the 90-vertex ball [{Cp*Fe(η(5):η(1):η(1):η(1):η(1):η(1)-P(5))}(12)(CuCl)(10)(Cu(2)Cl(3))(5){Cu(CH(3)CN)(2)}(5)] (2 a) containing pentaphosphaferrocene as a guest is also formed as a byproduct. With use of the triple-decker sandwich complex [(CpCr)(2)(μ,η(5)-As(5))] as a template the reaction between [Cp*Fe(η(5)-P(5))] and CuBr leads to the 90-vertex ball [(CpCr)(2)(μ,η(5)-As(5))]@[{Cp*Fe(η(5)-P(5))}(12){CuBr}(10){Cu(2)Br(3)}(5){Cu(CH(3) CN)(2)}(5)] (6), in which the complete molecule acts as a template. However, if the corresponding reaction is instead carried out with CuCl, cleavage of the triple-decker complex is found and the 80-vertex ball [CpCr(η(5)-As(5))]@[{Cp*Fe(η(5)-P(5))}(12){CuCl}(20)] (5) is obtained. This accommodates as its guest [CpCr(η(5)-As(5))], which has only 16 valence electrons in a triplet ground state and is not known as a free molecule. The triple-decker sandwich complex [(CpCr)(2)(μ,η(5)-As(5))] requires 53.1 kcal mol(-1) to undergo cleavage (as calculated by DFT methods) and therefore this reaction is clearly endothermic. All new products have been characterized by single-crystal X-ray crystallography. A favoured orientation of the guest molecules inside the host cages has been identified, which shows π⋅⋅⋅π stacking of the five-membered rings (Cp and cyclo-As(5)) of the guests and the cyclo-P(5) rings of the nanoballs of the hosts.

The self-assembly of [CpBnFe(η5-P5)] (CpBn = η5-C5(CH2Ph)5) with CuBr2 leads to the formation of an unprecedented rugby ball-shaped supramolecule consisting of 24 units of the pentaphosphaferrocene and an extended CuBr framework, which does not follow the fullerene topology. The resulting scaffold of 312 noncarbon atoms reveals three different coordination modes of the cyclo-P5 ligand including a novel π-coordination. The outer dimensions of 3.7 × 4.6 nm of the sphere approach the range of the size of proteins. With a value of 32.1 nm3, it is 62 times larger in volume than a C60 molecule. Surprisingly, this giant rugby ball is also slightly soluble in CH2Cl2.

Supersized mercury: Adducts with polymeric (left) or discrete supersandwich structures (right) form from mixtures of the trinuclear mercury complex [(o-C(6)F(4)Hg)(3)] (A) with the triple-decker complex [(CpMo)(2)(μ-η(6):η(6)-P(6))] (B) in the solid state. This arrangement arises from P···Hg interactions between opposing atoms of the P(6) units and the Hg(3) units (see picture; P-purple, Hg-orange, F-green, Mo-red, C-gray).