Low-Valent Metals in Metal-Organic Frameworks Via Post-Synthetic Modification

Metal-organic frameworks (MOFs) provide uniquely tunable, periodic platforms for site-isolation of reactive low-valent metal complexes of relevance in modern catalysis, adsorptive applications, and fundamental structural studies. Strategies for integrating such species in MOFs include post-synthetic metalation, encapsulation and direct synthesis using low-valent organometallic complexes as building blocks. These approaches have each proven effective in enhancing catalytic activity, modulating product distributions (i.e., by improving catalytic selectivity), and providing valuable mechanistic insights. In this minireview, we explore these different strategies, as applied to isolate low-valent species within MOFs, with a particular focus on examples that leverage the unique crystallinity, permanent porosity and chemical mutability of MOFs to achieve deep structural insights that lead to new paradigms in the field of hybrid catalysis.

A Coordination Polymer of Vaska's Complex as a Heterogeneous Catalyst for the Reductive Formation of Enamines from Amides

Low-valent metal-organic frameworks (LVMOFs) and related materials have gained interest due to their potential applications in heterogeneous catalysis.  However, of the rare examples of LVMOFs that have been reported, none have shown catalytic activity.  A low-valent metal-organic material constructed from phosphine linkers and Ir(I) nodes is reported.  This material is effectively a crystalline, insoluble analogue of Vaska's complex.  As such, this material reversibly binds O2 and catalyzes the reductive formation of enamines from amides.