Paddlewheel carboxylate complexes

Mixed-valence Ru"-Ru" paddlewheel carboxylate complexes also have potential for oxidation reactions after incorporation in a microporous lattice with porphyrinic ligands. This MOF can be used for oxidation of alcohols and for hydrogenation of ethylene. Both the porosity of the lattice and the abihty of the diruthenium centers to chemisorb dioxygen are essential for the performance of the catalyst [62, 64]. 

Dioxygen binding rates to diiron-carboxylate cores can be retarded and oxygenated intermediate can be trapped by embedding the metal complex into dendrimers.96 A third-generation dendrimer assembled around a paddlewheel diiron complex with 02CArTo1 reacts with 02 300 times slower than its nondendritic counterpart. 

Chromium, (ri6-benzene)tricarbonyl-stereochemistry nomenclature, 1,131 Chromium complexes, 3,699-948 acetylacetone complex formation, 2,386 exchange reactions, 2,380 amidines, 2,276 bridging ligands, 2,198 chelating ligands, 2,203 anionic oxo halides, 3,944 applications, 6,1014 azo dyes, 6,41 biological effects, 3,947 carbamic acid, 2,450 paddlewheel structure, 2, 451 carboxylic acids, 2,438 trinuclear, 2, 441 carcinogenicity, 3, 947 corroles, 2, 874 crystal structures, 3, 702 cyanides, 3, 703 1,4-diaza-1,3-butadiene, 2,209 1,3-diketones... 

Chromium complexes acetylacetone complex formation, 386 exchange reactions, 380 amidines, 276 bridging ligands, 198 chelating ligands, 203 carbamic add, 450 paddlewheel structure, 451 carboxylic adds, 438 trinuclear, 441 oorroles, 874... 

An elegant and efficient approach for the synthesis of structural models of carboxylate-rich non-heme dinuclear iron proteins involves the use of bulky ligands of the terphenyl carboxylate family [47, 48]. The resulting dinuclear iron(II) complexes can adopt two conformations, called the windmill and the paddlewheel motif (Scheme 2.9). 

Scheme 2.9 Equilibrium between windmill (left) and paddlewheel (right) structures of dinuclear iron(ll) complexes comprising ligands from the terphenyl carboxylate family (Scheme 2.8b).

Carbamate (R2NC02 ) complexes are similar electronically and structurally to monocarboxylate complexes, although they are not as accessible synthetically and are generally less stable. Unidentate, chelate, and bridging coordination modes have been observed, although the number of bridging modes found to date is less than that known for carboxylates. Syn-syn bridging is the most common, and bimetallic paddlewheel type structures (53) are known. 

More recently. Hupp and Nguyen used salen-based chiral Mn-complex as a chiral linker to generate chiral MOPM through pillaring with Zn-carboxylate paddlewheel [54], Bu et al. also employed the same sbategy to consbuct several homochiral open-framework materials using homochiral camphoric acid as a rigid linker [55]. 

Dioxygen diiron complexes have been synthesized by mimicking the probable intermediate structures in methane monooxygenase oxygenations. Examples are summarized in the recent review. One is the Fc2(i7-0)2 diamond core type and the other is the Fe2(tJ-02) peroxo type. Recently, an unusual Fe"-X-Fe (tl -02) species has been suggested in the reaction of O2 with carboxylate-bridged diiron(II,II) paddlewheel complexes, but its role in the oxygenation has not been clarified. ... 

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