Dibenzyl complex

Despite the radical character of these autoxidations, they may exhibit some selectivity. This can, for example, be seen in a recent report by Kim et al., which notes the selective transformation of a titaniiun(IV) diamido dimethyl complex into a mixed alkoxide alkyl (Eq. 15) and the complete lack of reactivity of the corresponding dibenzyl complex with O2 [35]. Both of these observations are probably the result of steric protection. When the metal complex becomes too hindered to allow close interaction with O2, the oxidation can no longer be initiated. 

Several major trends are apparent in Table XXV. (1) The redox potentials for any given ligand vary greatly with the nature of the metal. This correlation argues strongly that the electrochemical processes are primarily metal centered. An outstanding result is the exceptional stability toward oxidation of the Cr(III) d3, and Co(III) d6 complexes. (2) The values depend on the substituent R and show consistently that the order of stability of the oxidized or reduced species varies from the dibenzyl complexes to the dicyclohexyl complexes. The former are easier to reduce and more difficult to oxidize, while the latter are the easier to oxidize and more difficult to reduce. 

Dibenzyl complexes with calcium, strontium, barium, 2, 120 with Ti(IV), 4, 343, 4, 349 with Zr(IV), 4, 783, 4, 785-786 with Zr(IV) mono-Cp complexes, 4, 833 Dibenzylgallium azides, for semiconductor growth, 12, 17 Dibenzyl imido complexes, with Ti(IV), 4, 352-353 Dibenzyl phosphoranimino carbenes, with Zr(IV), 4, 798 Dibenzyl titanasilsesquioxanes, synthesis, 4, 493 Dibenzyo-tetramethyltetraaza[14]-annulenes, with Zr(IV),... 

Lanthanum dibenzyl complexes with triazanonane-silylamide, amidine and 1,3-diketiminate monoanionic ancillary ligands were also prepared by in situ peralkylation in the presence of the protonated ligand or by com-plexation (for 1,3-diketiminate) with lanthanum tribromide and subsequent alkylation. The coordination polymer [p-r 2 r 1-ArNC(Me)CHC(CH2)-NAr]2La[K(THF)4] n formed by H-abstraction from one of the diketimi-nate Me groups and a ligand redistribution.14... 

A number of titanium derivatives containing carbazole ligands have been isolated. Reaction of Ti(GH2Ph)4 with carbazole yields the dibenzyl complex Ti(GH2Ph)2(cb)2 (Scheme 45). The reaction of this compound with 2,6-dimethylphenyl isocyanide leads to titanium derivatives containing new carbon-carbon bonds (Section 4.05.2.3).109,110... 

Dibenzyl complexes stabilized by tridentate dianionic ligands containing hard and soft pendant donors have been described. Reactions of Ti(CH2Ph)4 with the corresponding aminophenols give the mononuclear pentacoordinate dibenzyl Ti derivatives (Scheme 68). Activated with MAO, these complexes have been used as catalysts for ethylene polymerization, showing marked activity enhancements for the compounds containing soft donor substituents.141... 

Treatment of a benzene solution of the sterically crowded bis(aryloxide)zirconium dibenzyl complex 5 with BIC F5)3 leads to the facile formation of the corresponding zwitterionic species 6 (Scheme 3).44 The molecular structure of 6 features a three-legged piano-stool geometry about Zr with the 7/ -bound benzyl group and the tightly associated benzyl borate anion through r/ -arcne coordination this complex is stable in solution in the presence of propylene and phenylpropyne. In contrast, treatment of the 2,6-di-Buc-substituted aryloxide dibenzyl derivative 7 with B(C6Fs)3 forms the cyclometallated compound 8 after elimination of toluene (Scheme 3) 45 compound 8 was structurally characterized. 

Reaction of the sterically encumbered diamido zirconium dibenzyl complex 9 with B(C6Fs)3 in toluene at ambient temperature affords the cyclometallated product 10 after benzyl abstraction and elimination of... 

A hydrocarbyl elimination approach is used to produce the Zr(rv) dibenzyl complex incorporating a tridentate bis(amido) silylether [iV, 0,(V ] complex 18261 (Equation (13)). The molecular structure of 182 features a distorted tbp geometry with an approximately linear ZrN20 unit and the two amido nitrogen atoms occupying approximately axial positions.One benzyl group is -coordinated. When activated with MAO, complex 182 shows moderate activity for ethylene polymerization. 

The reaction of the dilithium salt 225 with ZrCU yields the undesired tetraaryl complex with two dianionic ligands bound to one Zr, irrespective of the ligand-to-Zr ratio employed. However, the reaction of 225 with Zr(CH2Ph)2Gl2(Et20)2 produces the desired dibenzyl complex 226 incorporating one tridentate bis(cr-aryl)amino [C ligand184 (Scheme... 

A unique cyclometallation process was utilized to synthesize zirconium dibenzyl complex 229 involving the reaction of 2-(2 -phenol)-6-arylpyridine with Zr(CH2Ph)4185 (Equation (16)). This complex is supported by an unsymmetric tridentate, phenolate-pyridine-carbanion [CT,N,0 ]-typs ligand. Both the solution NMR data and... 

Zirconium and hafnium dibenzyl complexes 251 incorporating a tetradentate, biaryl-bridged bis(iminooxazolidine) ligand were conveniently prepared using the alkane elimination approach202 (Scheme 50). These six-coordinate complexes are C2-symmetric, and the auxiliary benzyl groups occupy mutually rir-positions however, upon activation... 

Zirconium and hafnium dibenzyl complexes 258 incorporating tetradentate bis(bulky phenoxy) amines with an additionally heteroatom (N, O, or. Si-donor containing pendant sidearm are produced from the reaction of the... 

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