Post-synthetic metallation is employed strategically to imbue metal-organic frameworks (MOFs) with enhanced performance characteristics. However, obtaining precise structural information for metal-centred reactions that take place within the pores of these materials has remained an elusive goal, because of issues with high symmetry in certain MOFs, lower initial crystallinity for some chemically robust MOFs, and the reduction in crystallinity that can result from carrying out post-synthetic reactions on parent crystals. Here, we report a new three-dimensional MOF possessing pore cavities that are lined with vacant di-pyrazole groups poised for post-synthetic metallation. These metallations occur quantitatively without appreciable loss of crystallinity, thereby enabling examination of the products by single-crystal X-ray diffraction. To illustrate the potential of this platform to garner fundamental insight into metal-catalysed reactions in porous solids we use single-crystal X-ray diffraction studies to structurally elucidate the reaction products of consecutive oxidative addition and methyl migration steps that occur within the pores of the Rh-metallated MOF, 1·[Rh(CO)2][Rh(CO)2Cl2].

Won by the hare: A new crystalline microporous solid was prepared that is composed of discrete organic cages made entirely from carbon–carbon bonds. The porosity of this material can be controlled by simple kinetic methods, which afford reproducible access to either a non‐porous or porous polymorph.

The binuclear complexes Cp*(dppe)FeC CCCCCM(dppe)Cp* (6, M = Fe; 8, M = Ru) were obtained in good yield by treatment of the iron chloro complex Cp*(dppe)Fe−Cl (5) in the presence of KF with the bis(silylated) hexatriyne Me 3 SiCCCCCCSiMe 3 and the ruthenium complex Cp*(dppe)RuCCCCC CSiMe 3 (7), respectively. The oxidized species 6(PF 6 ) n (n = 1, 2) and 8(PF 6 ) were obtained in ca. 80% yield by treatment of the parent neutral compounds with 1 or 2 equiv of [Cp 2 Fe](PF 6 ) in THF or dichloromethane at −78 °C. The CV of these compounds show three reversible waves with a separation larger than 0.5 V. The salts 6(PF 6 ) n (n = 1, 2), and 8(PF 6 ) were characterized by XRD. Quantum chemistry calculations performed at the DFT level on the oxidized species show a strong contribution of the −C 6 − spacer to the delocalization of the spin density. IR spectra analyzed with the support of TD-DFT calculations are consistent with the delocalization of the odd electron on the fast IR time scale for the two mixed-valence complexes 6(PF 6 ) and 8(PF 6 ). Combined ESR measurements on rigid glass and on single crystal samples clearly establish that the electronic properties of MV species and particularly their magnetic anisotropies depend on the conformation of the molecules. In the case of the doubly oxidized species 6(PF 6 ) 2 , which carries two unpaired electrons, it is shown that the singlet vs triplet ground states can be inverted by the rotation of one metal end with respect to the other around the all-carbon chain axis. Very strong NIR bands are found for the symmetric 6(PF 6 ) and nonsymmetric 8(PF 6 ) MV (mixed-valence) derivatives allowing the determination of very large electronic couplings (H ab = 3070 and 4025 cm −1 , respectively).