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1. Biological Pincer Complexes

   https://doi.org/doi.org/10.1002/cctc.202000575  

   Nevarez, Jorge L.; Turmo, Aiko; Hu, Jian; Hausinger, Robert P. (September 2020, ChemCatChem)

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   At least two types of pincer complexes are known to exist in biology. A metal-pyrroloquinolone quinone (PQQ) cofactor was first identified in bacterial methanol dehydrogenase, and later also found in selected short-chain alcohol dehydrogenases of other microorganisms. The PQQ-associated metal can be calcium, magnesium, or a rare earth element depending on the enzyme sequence. Synthesis of this organic ligand requires a series of accessory proteins acting on a small peptide, PqqA. Binding of metal to PQQ yields an ONO-type pincer complex. More recently, a nickel-pincer nucleotide (NPN) cofactor was discovered in lactate racemase, LarA. This cofactor derives from nicotinic acid adenine dinucleotide via action of a carboxylase/hydrolase, sulfur transferase, and nickel insertase, resulting in an SCS-type pincer complex. The NPN cofactor likely occurs in selected other racemases and epimerases of bacteria, archaea, and a few eukaryotes. 

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2. Pincer Chemistry and Catalysis

   https://doi.org/10.1002/ejic.202000858  

   Koten, Gerard; Hollis, T. Keith; Morales‐Morales, David (December 2020, European Journal of Inorganic Chemistry)

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3. Decarbonylative ether dissection by iridium pincer complexes

   https://doi.org/10.1039/d0sc03736b  

   Yoo, Changho; Dodge, Henry M.; Farquhar, Alexandra H.; Gardner, Kristen E.; Miller, Alexander J. (November 2020, Chemical Science)

   A unique chain-rupturing transformation that converts an ether functionality into two hydrocarbyl units and carbon monoxide is reported, mediated by iridium( i ) complexes supported by aminophenylphosphinite (NCOP) pincer ligands. The decarbonylation, which involves the cleavage of one C–C bond, one C–O bond, and two C–H bonds, along with formation of two new C–H bonds, was serendipitously discovered upon dehydrochlorination of an iridium( iii ) complex containing an aza-18-crown-6 ether macrocycle. Intramolecular cleavage of macrocyclic and acyclic ethers was also found in analogous complexes featuring aza-15-crown-5 ether or bis(2-methoxyethyl)amino groups. Intermolecular decarbonylation of cyclic and linear ethers was observed when diethylaminophenylphosphinite iridium( i ) dinitrogen or norbornene complexes were employed. Mechanistic studies reveal the nature of key intermediates along a pathway involving initial iridium( i )-mediated double C–H bond activation. 

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4. Backbone Dehydrogenation in Pyrrole-Based Pincer Ligands

   https://doi.org/10.1021/acs.inorgchem.8b01643  

   Krishnan, V. Mahesh; Davis, Ian; Baker, Tessa M.; Curran, Daniel J.; Arman, Hadi D.; Neidig, Michael L.; Liu, Aimin; Tonzetich, Zachary J. (July 2018, Inorganic Chemistry)
5. (Electro-)chemical Splitting of Dinitrogen with a Rhenium Pincer Complex: (Electro-)chemical Splitting of Dinitrogen with a Rhenium Pincer Complex

   https://doi.org/10.1002/ejic.201901278  

   van Alten, Richt S.; Wätjen, Florian; Demeshko, Serhiy; Miller, Alexander J.; Würtele, Christian; Siewert, Inke; Schneider, Sven (April 2020, European Journal of Inorganic Chemistry)

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