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The synthesis and structural characterization of [alpha]-diimine iron complexes which contain intermediate spin-state iron centers is described.

The bis (imino) pyridine iron complex, [{2,6-(MeC=N-2,6-Pr2C6H3)2C5H3N}FeCl2], in combination with MAO and ZnEt2(> 500 equiv), is shown to catalyze polyethylene chain growth on zinc. The catalyzed chain growth process is characterized by an exceptionally fast and reversible exchange of the growing polymer chains between the iron and zinc centers.

Results describe the synthesis of a glycosphingolipid D,L-glucosylceramide in high yields using allylboration-ring closing and metathesis-ring opening method. Data indicate that the procedure is flexible and accommodates variations in the amide or hydrocarbon regions of the molecule.

Group 4 metal complexes containing two bidentate ligands combining phenoxide and tertiary phosphine donors are investigated. Bis(phosphanyl(phenoxide) complexes of the group 4 metals, upon activation by methylaluminoxane, are highly active for ethylene ad propylene polymerization.

The 1:1 reactions of nine potentially tridentate salicylaldimines with tin(II) diamides, Sn[(N[R.sub.2]).sub.2] (R = Me, Et, Pr, Si[Me.sub.3]) are examined. The studies have shown that the transfer of the amide is reversible, with both alcoholysis and the initiation of rac-lactide polymerization mediated by the terminal amide tautomer.

The synthesis and the formation of mono- and bis-chelates in various magnesium and zinc complexes are studied. The ligands show a greater resistance towards bis-chelation due to presence of more N-aryl substituents.

The development of the chemistry of tridentate, [2,6-[ArN=CR.sub.2][C.sub.5][H.sub.3]N] and its associated metal complexation chemistry is reviewed. The review reveals the capability of the ligand system to accept or donate negative charge by influencing the redox potential of coordinated metals.

A family of tin(II) complexes supported by beta-diketiminate ligands is investigated as initiators for the polymerization of rac-lactide. A B3LYP density functional computational study has indicated that insertion of the first lactide monomer into the tin(II) alkoxide bond is facile, with the induction period arising from a slower insertion of the second monomer units.

A description is provided of highly active ethylene polymerization catalysts supported by tridentate phenoxyamide ligands. It is shown that the incorporation of halo substituents within the amino aryl units leads to catalysts with dramatically improved ethylene polymerization activities and excellent 1-hexene incorporation.

High throughput screening (HTS) of a 205 member Schiff base salicylaldimine ligand library derived from salicylaldehydes bearing bulky ortho-substituents identified two new classes of highly active chromium based systems for new classes of highly active chromium based systems for the oligomerization and polymerization of ethylene. The polymerization system comprises bidenTate ortho-substituted anthracenyl Schiff bases bearing small primary or secondary alkyl imine constituents.

A highly active transition metal ethylene polymerization catalyst across the transition series is investigated for their ability to catalyze chain growth on zinc. The results concluded that the catalyzed chain growth (CCG) is favored by a reasonable match between the bond dissociation energies of both the main group and transition metal alkyl species.

A detailed investigation of the MeLi reaction is conducted along with related reactions of bis(imino)pyridines with magnesium dialkyl and zinc dialkyl reagents. The synthetic, structural, and mechanistic investigation that examines the site selectivity of the alkylation, the reversibility of the process, the structures of key alkylation products, and the mechanism by which the alkylation process occurs, is described.

A report is presented, which describes a density functional theory (DFT) study into the polymerization of rac-Lactide initiated by mononuclear (BDI)MgOMe(THF) with a view to obtaining a greater understanding of the intricacies associated with metal-alkoxide mediated ring-opening polymerization (ROP), as well as addressing the stereocontrol found in the beta-diketiminate metal systems.

An unprecedented migration of an amino group to the imine carbon atom of family of tridentate salicylaldiminato complexes is described to give highly unusual tetradentate ligands. A reverse process disassembles the so-formed tetradenate ligands to afford single-site initiators for lactide polymerization.

Remarkable stereocontrol in the polymerization of rac-lactide by aluminum initiators supported by tetradentate aminophenoxide ligands is found. The polymerization are well-controlled and living, affording PLA materials that range from highly isotactic to highly heterotactic, depending upon the ligand substitution pattern.

Research has been conducted on central pyridine core in bis(imino)pyridine iron and cobalt ethylene polymerization catalysts. The effect of variations on this core has been investigated via the study of the three classes of ligands, and the results of ethylene polymerization have been discussed.

The authors review the publications on olefin polymerization catalysis. The topics of interest include the analysis of the systems capable of catalyzing the living polymerization of olefinic monomers.

A new and exceptionally active, homogeneous chromium ethylene oligomerization catalyst supported by a tridentate bis(benzimidazolyl)amine ligand that affords a hitherto unobserved distribution of higher alpha-olefin products is reported. The observation suggests that it should be possible to further control the product distribution by judicious ligand modifications and through changes to the reaction conditions.

The proof of concept findings, which show that activity could indeed be varied by redox switching of a ferrocenyl unit contained within the ligand backbone of a lactide polymerization catalyst, is described. The results demonstrate that remote redox-active ligand substituents might be exploited to control the activity of single-site polymerization initiators and redox switch could also be used to oscillate a catalyst between sites of differing activities.

Two homogeneous oligomerization catalysts that would allow the chain-lengthened products to be examined by gas chromatography and mass spectrometry are examined. Polyethylene chain growth occurs predominantly through metallacyclic intermediates and the nonincorporation of higher alpha-olefins strongly implicates the involvement of large ring metallacycles.

Bis(imino)pyridine iron complexes bearing ether and thioether backbone substituents are synthesized and evaluated for the polymerization ethylene. It is stated that the methoxy dereivative is inactive whereas bulky phenoxides or thioether derivatives afford activities as high as the most active systems.

New Cr(III) complexes of CNC-pincer carbene ligands which in combination with MAO give exceptionally active catalysts for ethylene oligomerization are reported. The catalyst benefits form a longer lifetime at lower temperatures, though the rate of ethylene conversion also reduces at lower temperature.

Atom transfer radical polymerization (ATRP) has proved to be a powerful method for the synthesis of materials through controlled radical polymerization. Several different metal-ligand combinations have been investigated, including the systems based on Pd(super 4), Rh(super 5), Ni(super 6) and Fe.

The organoaluminum boryloxides species can catalyze the formation of boroxine, which are trimeric boron, related to the hexanuclearaluminoxanes consisting of two stacked aluminoxane rings.