Hydrothermal Synthesis of Microporous Transition Metal Squarates: Preparation and Structure of [CO₃(μ₃‐OH)₂(C₄O₄)₂]·3H₂O

Abstract

a 0.4 I L 3800 3800 3700 3600 3500 3400 +/cm-'-Figure 5. Comparison of the OH regions of the IR spectra ofactivated cloverite (a) and Y zeolite (b. Linde LZY62, Si/Al = 2.4). The spectra were normalized to 10 mg solid, and based on the structures of the solids the ratio between the area of OH bands in cloverite and Y zeolite should be at least approximately 1 :3; however, the observed value is only 1 :40. I = Absorbance.In conclusion, this study reveals that the postulated terminal OH groups in the framework of cloverite are not detectable by IR spectroscopy. Free OH groups, in particular those due to POH groups that vibrate at 3676 cm-', are observed before and after activation of cloverite at 573 K under ozone. Their number increases upon activation but remains quite low, about 3.5 % of the expected number, indicating that they correspond to defect sites. This study does not cast doubt on the results of the X-ray structure analysis, but rather on whether the terminal oxygen atoms in the structure really belong to hydroxyl groups.Many microporous main group oxides have been prepared by hydrothermal synthesis"] but it has long been a goal to produce lacunary materials with modulated catalytic activity by constructing frameworks with d-block metals in close proximity to the voids. Haushalter et al. have shown how this can be achieved for vanadium and molybdenum phosphates.['] The usefulness of superheated fluids for preparing extended frameworks based on metal-ligand interactions has recently been demonstrated both by ourselvesL3] and and we now wish to report the extension of this technique to the preparation of a cobalt squarate with a microporous structure. The cobalt -squaric acid system has been extensively investigated under ambient condit i o n~'~] and gives compounds based on the framework found in 1 in most cases; analogous structures are also formed by the corresponding compounds of manganese, iron, nickel, and zinc. We report herein on compound 2, which has a structure unlike those previously observed.

Bimetallic Metal‐Organic Frameworks Containing the ${\rm [M(2,}x-{\rm pdc)^{2-}_{2}}]$ (M = Cu, Pd, Pt; x = 4, 5) Building Block – Synthesis, Structure, and Magnetic Properties

“…Co1 and Co2B form squares by cis-µ 3 ϪOH bridges, forming undulating chains of edge-and vertex-sharing Co 3 OH triangles (Fig. 6, bottom); this topology has been observed extensively elsewhere [14,23]. H 2 O ligands (O6 and O7) are cisoriented to the hydroxides and the regular octahedral environment of Co1 is completed by interaction with an adjacent metalloligand 4-carboxylate.…”

Emergent magnetic order and correlated disorder in formate metal-organic frameworks

“…Co 3 (OH) 2 (sq) 2 .3H 2 O has significant frustration within its CoO 6 ribbons, and unusually undergoes a phase transition upon dehydration. [42] In Mn(tca) strong frustration is observed and is relieved by the formation of an incommensurate 3D structure. [43] Tb(DCO 2 ) 3 is an excellent example of a magnetic MOF with interesting properties at low temperatures and a physical realisation of a stacked triangular lattice, forming chains of Tb ions (Figure 4).…”

Mixed Inorganic–Organic Anion Frameworks: Synthesis and Crystal Structure of Fe4(PO4)2(C2O4)(H2O)2

“…Recent reports of quite thermally robust metal-organic framework Corrresponding author. materials (11)(12)(13) prompted us to explore the feasibility of preparing mixed organic-inorganic frameworks by hydrothermal methods. In this way we may hope to retain some of the robustness of the inorganic framework while including the much greater chemical and topological flexibility of the organic framework.…”