Bis-phenoxides

The trigonal planar zinc phenoxide complex [K(THF)6][Zn(0-2,6-tBu2C6H3)3] is formed by the reaction of a zinc amide complex, via a bis phenoxide, which is then further reacted with potassium phenoxide. TheoX-ray structure shows a nearly perfect planar arrangement of the three ligands with zinc only 0.04 A out of the least squares plane defined by the three oxygen atoms.15 Unlike the bisphenoxide complexes of zinc with coordinated THF molecules, these complexes are not cataly-tically active in the copolymerization of epoxides with C02. The bisphenoxide complex has also been structurally characterized and shown to be an effective polymerization catalyst. 43... 

A series of bis(phenoxide) aluminum alkoxides have also been reported as lactone ROP initiators. Complexes (264)-(266) all initiate the well-controlled ROP of CL, NVL.806,807 and L-LA.808 Block copolymers have been prepared by sequential monomer addition, and resumption experiments (addition of a second aliquot of monomer to a living chain) support a living mechanism. The polymerizations are characterized by narrow polydispersities (1.20) and molecular weights close to calculated values. However, other researchers using closely related (267) have reported Mw/Mn values of 1.50 and proposed that an equilibrium between dimeric and monomeric initiator molecules was responsible for an efficiency of 0.36.809 In addition, the polymerization of LA using (268) only achieved a conversion of 15% after 5 days at 80 °C (Mn = 21,070, Mn calc 2,010, Mw/Mn = 1.46).810... 

Bis(4-pentenyl) ligands, in platinum(II) complexes, 8, 504 Bis(phenoxide) compounds, in chromium complexes,... 

Mn(III). Structurally characterized higher valent manganese complexes with phenoxide-type ligation are limited to Mn(III) and Mn(IV) Schiff base complexes (128-135), Mn(III) and Mn(IV) catecholates (136-139), Mn(III) and Mn(IV) salicylates (140-142), and Mn(III) bi-phenoxides (143). However, of these ligands, only biphenoxide is similar electronically to tyrosine Mn(III) complexes of these ligands, in general, lack the intense phenoxide - metal charge transfer band centered at 435 nm. 

Storr T, Verma P, Pratt RC et al (2008) Defining the electronic and geometric stmcture of one-electron oxidized copper-bis-phenoxide complexes. J Am Chem Soc 46 15448-15459... 

Seeking robust NHC-incorporating pincer-type chelating ligands, we designed a bis-phenoxide-NHC ligand that combines two phenoxide substituents directly connected to the nitrogen atoms [49]. It was envisioned that such a structure would be suitable for coordination to various metals across the periodic table. 

The bis-phenoxide salts were prepared In anhydrous form by azeotropic drying, starting with the bis-phenol and an alkali hydroxide. They were polymerized by displacement... 

However, nitro-N-alkylphthalimides, 7 ("protected" nitro-phthalic anhydrides), when treated with bis-phenoxide salts, 2, underwent smoothe displacement to produce bis ether-bis-imides, 8. These can be readily purified to remove all of the tyT>es of impurities which, in the prior method,... 

The activity of 36 200 kg mol h (Table 15.1) is comparable to the extremely high activities reported for zirconium amine-bis(phenoxide) complexes [20]. Upon reducing the polymerization temperature to -30 "C, the activity dropped to 2030 kg mol h" however, at this temperature the poly(l-hexene) produced... 

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