Aryloxo ligands

In addition to group 6 transition metal catalysts, bulky aryloxo ligands can replace the chlorine ligand(s) of NbCls to form Nb(dmp) CC s(solvent) (5 1-2), which exert unique ability with co-catalysts such as EtMgBr or EtsAl to... 

A novel intermolecular type of trimer formation occurs with 2-hydroxy-5,10,15,20-tetraphenylporphyrinatoiron(lll). Deprotonation of the 2-hydroxy group creates an anionic aryloxo ligand for another Fe center, and the cyclic trimer thus forms. The metal ions are weakly coupled high-spin Fe centers (/Xeff = 5.4 0.2/xb), and the 3-H NMR resonances of this low-symmetry trimer are uniquely found at very negative chemical shifts (-89.8, -94.7 and -99.3 ppm at 291 K) and are very broad (670-690 Hz), while all other /3-pyrrole protons resonate in the +82 to +62 ppm region typical of high-spin Fe in monomeric complexes.The structure of the trimeiic complex has also been reported. ... 

A significant reduction in cyclometallation rates was observed with bulkier substituents at the meta position of the aryloxo ligands. 

Titanacycle compounds supported by aryloxo ligands catalyze cross-coupling and oligomerization reactions involving 1,3-cyclohexadiene, 1,3-cyclooctadiene, and a-olefins. Mechanistic aspects are reported.244 The regio- and the... 

The synthesis and characterization of a family of mono-Gp dichloro complexes with disubstituted aryloxo ligands has been reported, and their molecular structures provide some means of quantifying the number of electrons donated to the metal center by an aryloxide ligand. These complexes can be reduced by Grignard reagents or LiBu11 in the presence of enynes. The formation of metallacyclic derivatives (Scheme 348) was observed for the Cp but not for the Cp complexes, as deduced by NMR spectroscopy. The complexes have been investigated as catalysts... 

Scheme 350 shows the structures of a number of mono-Cp titanium complexes with more elaborately substituted aryloxo ligands. The compounds are formed by the reaction of Cp TiCl3 with 1 equiv. of the substituted phenol in the presence of an excess of pyridine or by treatment of the lithium phenoxide with Cp TiCl3 some of them have been... 

Mono-Cp chloro titanium complexes containing a sulfide-bridged chelating bis(aryloxo) ligand have been synthesized and characterized (Scheme 383). The complex Ti(tbmp)Gl2 reacts with LiCp (Cp =Cp, Cp, G5H4SiMe3) to... 

Mono-Cp alkoxo and aryloxo titanium thiolates and sulfides have been widely reported. These complexes show an interesting reactivity, including C-H and G-S bond activation and reduction of Ti(iv) to Ti(m). The incorporation of bulky aryloxo ligands in the coordination environment of the titanium center limits some of this reactivity and alters the chemistry of the compounds considerably. The implications of the electronic and steric effects of these ancillary ligands have been considered.1005-1008... 

Rothwell et al prepared some metallacyclic complexes 49-51 bearing bulky aryloxo ligands (ArO = 2,6-diphenylphenoxide or 2,6-diisopropylphenoxide) [158,159]. Some chelating aryloxy complexes such as 52 in combination with MAO are catalysts for... 

The 1,2-addition of C—H bonds across metal-heteroatom bonds has been reported for two different classes of complexes early transition metal d° complexes with imido ligands and late transition metal complexes with amido, hydroxo, and aryloxo ligands (Scheme 11.36). These transformations are potentially related to o-bond metathesis reactions discussed above however, the presence of a lone pair on the heteroatom that receives the activated hydrogen may impart important differences. 

SCHEME 11.47 Proposed mechanism for Rh(I)-mediated C—H activation with hydroxo, alkoxo, and aryloxo ligands (R = t-Bu S = solvent). 

Since liatf-iiiamKenes containing aryloxo ligands exhibited high catalytic activities for both ethylene and styrene polymerizations. 34a.b.d.gJ the possibility of styrene polymerization with these type of complexes was explored.(3Hcl However, 25b showed extremely low (or no) catalytic activities, and the isolated polymer from the mixture was atactic polystyrene that is produced by d-MAO itself, as reported previously.[34g]... 

Alkoxo/Aryloxo Ligand Architecture Complex Polyhydric Ligands for New Catalysts of the COi-Epoxide Coupling... 

Cyclohexene could not be copolymerized using a/isa-metallocenes. Recently, copolymerization of ethene with cyclohexene with efficient cyclohexene incorporation by using non-bridged half-titanocenes containing an aryloxo ligand was reported by Nomura [37]. 

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