Structural Diversity in Metal-Organic Frameworks Built from Rigid Tetrahedral [Si(p-C6H4CO2)4]4- Struts

The silicon-based connector [Si(p-C6H4CO2)(4)](4-) (L) has been employed in the construction of six new metal-organic framework (MOF) materials, all of which have been characterized by single crystal X-ray diffraction techniques. The isostructural frameworks [Cd-2(L)(H2O)(2)]center dot(DMA) and [Mn-2(L)(H2O)(2)]center dot(DMA)(2.5), IMP-8Cd and IMP-8Mn, respectively. contain extended [M(CO2)(2)](n) chains, often termed rod SBUs (secondary building units), which arc cross-linked into a 3D network by tetrahedral L struts to give microporous networks, hi contrast, [Cu-2(L)(H2O)(2)]center dot(DMA)(12) (IMP-9) contains dinuclear paddle-wheel Cu-2(CO2)(4) SBUs connected together with L struts to give an overall PtS type net. [Me2NH2](2)[Cd-3(L)(2)(H2O)(2)]. (DMA)(8)(H2O)(8), [Me2NH2](2)[Zn-3(L)(2)]center dot(DMF)(6) and [Me2NH2](2)[Zn-3(L)(2)]center dot(DMF)(3) (IMP-10, IMP-11. and IMP-12, respectively) all contain anionic 31) frameworks which are charge balanced by the presence of dimethylammonium cations within their pores. These dimethylammonium cations arise from the hydrolysis of DMA or DMF, or they can he in rod need directly by addition of [Me2NH2]CL IMP-10, IMP-11, and IMP-12 all contain trinuclear octacoordinate SBU nodes. although subtle differences in the geometry of these SBUs result in the formation of different network topologies in each case. Examples of MOFs containing rigid tetrahedral carboxylate connectors are currently uncommon, and several previously unobserved topologies are introduced in this study.