Reduction of phenol-imine derivatives RЈN=CH(3,5-R 2 C 6 H 2 -2-OH) (R = tBu; RЈ = C 6 H 5 1a, p-MeC 6 H 4 1b, Cy 1c, tBu 1d, 2,6-Me 2 C 6 H 3 1e; R = H; RЈ = p-MeC 6 H 4 1f; Cy = cyclohexyl) with MBH 4 (M = Li, Na) or AlLiH 4 in ethyl ether or thf at room temperature affords the phenol-amine compounds RЈNHCH 2 (3,5-R 2 C 6 H 2 -2-OH) 2a-c and 2e,f. The N-R- [2,4-ditert-butyl]benzo-1-oxa-3-azine species (R = tBu 2d1, 2,6-Me 2 C 6 H 3 2e1) are obtained by Mannich reaction of 2,4-ditert-butylphenol with RNH 2 in refluxing methanol. Intermediate 2d1 is converted in ethanol at room temperature into N-tert-butyl [2-hydroxy-3,5-di-tert-butyl]benzylamine (2d), whereas 2e is not obtained from 2e1 by using this procedure. N-alkyl,N-tert-butyl[2-hydroxy-3,5-di-tert-butyl]benzylamine compounds tBuN(R)CH

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Two diiminobis(phenolate) zirconium complexes [C6H10-{NCH-(3,5- t Bu2C6H2-2-O)-κO}2]ZrX2 [X = CH2Ph (1), Cl (3)] have been synthesized and characterized by NMR solution spectroscopy. Complex 1 was found conformationally stable and isolated in the octahedral C 2 symmetric form. When exposed to the light in hydrocarbon solution, 1 readily undergoes to 1,2 benzyl migration converting the diiminobis(phenolate) ligand in the corresponding benzylamidoiminobis(phenolate). Complex 3 is more thermally stable and found in slow equilibrium between the cis-α and cis-β forms with the former largely prevalent (9:1 molar ratio). The rate of interconversion between the two diastereoisomers was estimated in 3.6 × 10-1 s-1 by NMR exchange spectroscopy (EXSY). 1 and 3 are active ethylene polymerization catalysts after reaction with MAO or [CPh3][B(C6F5)4]/Al- i Bu3. The polydispersity index of polyethylene produced by 1 is about 2, suggesting the presence of a single active species and that the symmetry of the precatalyst is retained during polymerization. The catalyst is stable over 3 h, and the polymerization activity linearly increases with time. Copolymers of ethylene with propylene or 1-hexene were synthesized, and the 13C NMR analysis of their microstructure suggested the highly regioregular 1,2 insertion of the 1-olefin and the inability of the ligand environment to express stereochemical control during monomer insertion.

The Schiff base N,N ‘-o-phenylenebis(3,5-di-tert-butyl-salicylideneimine) (1; t Bu4salophenH2) reacts with 1 equiv of Zr(η5-C5H5)Cl3·DME in the presence of 2.2 equiv of NEt3 in pentane to give the monocyclopentadienyl bis(phenoxo-imino) monochloro zirconium derivative Zr(η5-C5H5)[C6H4-1,2-{NCH(3,5- t Bu2C6H2-2-O)}2]Cl (2). Moreover, 2 equiv of the monolithiated reagent derived from 3-tert-butyl-N-ethylsalicylaldimine by reaction with Li n Bu in hexane reacts at −78 °C with 1 equiv of Zr(η5-C5H5)Cl3·DME in THF to yield the corresponding monocyclopentadienyl bis(phenoxo-imino) monochloro zirconium complex Zr(η5-C5H5)[CH3CH2NCH{(3- t BuC6H3-2-O)}]2Cl (5) after elimination of LiCl. Methylation of 2 with MgClMe in pentane or toluene at −78 °C affords Zr(η5-C5H5)[1,2-C6H4{NCH(3,5- t Bu2C6H2-2-O)}{NCH(Me)(3,5- t Bu2C6H2-2-O)}] (3) as a result of the reduction of one of the CN bonds of the coligand. The hydrolysis of 3 gives the new organic compound [C6H4{NCH(3,5- t Bu2C6H2-2-OH)}{NCH(Me)(3,5- t Bu2C6H2-2-OH)}] (4), which was also quantitatively isolated by reaction of 1 with MgClMe followed by treatment with a saturated solution of NH4Cl in water. All of the reported compounds were characterized by the usual analytical and spectroscopic methods, and the molecular structure of 5 was determined by X-ray diffraction analysis from suitable single crystals. The catalytic activities of 2, 3, and 5 for ethylene polymerization using MAO as cocatalyst were determined.

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