Colin Morton

Complexes of zirconium with aryl substituted triamidoamines: molecular structures of amide and alkyl derivatives

Abstract Reactions of the arylated TREN derivatives N(CH 2 CH 2 NHAr) 3 [Ar=2,4,6-C 6 Me 3 H 2 (H 3 TMT), 3,5-C 6 Bu t 2 H 3 (H 3 TDT)] individually with Zr(NMe 2 ) 4 and Zr(CH 2 Ph) 4 give the azazirconatranes [Zr(TMT)(NMe 2 )], [Zr(TDT)(NMe 2 )] and [Zr(TDT)(CH 2 Ph)] and unexpectedly [Zr(HTMT)(CH 2 Ph) 2 ]. The molecular structures of [Zr(TMT)(NMe 2 )] and [Zr(TDT)(CH 2 Ph)] show that the triamidoamine ligand is arranged with the usual three-fold symmetry about the metal and that the aryl substituents form a bowl cavity with the apical ligand at the base. The reactions of the alkyl with dihydrogen lead to decomposition, and a hydride species such as that proposed in earlier studies could not be detected.

Substituent effects on the cyclo-manganation reaction X-ray crystal structure of Mn{2-(nBu-N=CH) 5-(NO2) C6H3}(CO)4

Abstract The cyclometallation reaction between methylmanganese pentacarbonyl and a number of Schiffs bases has been studied. The dependence of the rate of reaction upon ligand substituents has been investigated, demonstrating a rate enhancement with more electron-rich ligands. The X-ray structure of Mn2-(nBu-N=CH)5-(NO2)C6H3(CO)4 has been determined.

Awakening a dormant catalyst: salicylaldimine systems for ethene/tert-butylstyrene copolymerization

A group of readily available zirconium catalysts incapable of ethene-co-styrene polymerization are remarkably active and selective for the production of the new polymer ethene-co-tert-butylstyrene via a single site mechanism.

Control of metal/ligand stoichiometry and structure in aminopyridinato complexes of zirconium: N-alkyl is better than trimethylsilyl

N-Adamantyl-2-aminopyridines (HL) readily form C2-symmetric aminopyridinato complexes with zirconium [ZrL2X2] (X = Cl, NMe2, CH2Ph, CH2But) which are stable with respect to ligand redistribution and lead to catalysts for ethylene polymerisation with similar productivity to the related [Zr(benzamidinate)2X2] system.

Arylaminopyridinato complexes of zirconium

A range of 2-arylaminopyridines (HL) are synthesised readily from bromopyridines and amines using palladium-catalysed amination. Protonolysis reactions of these proligands with ZrX(4)(X = NMe(2), CH(2)Ph, CH(2)Bu(t)) yield zirconium complexes of the type [ML(n)X(4-n)], several of which have been characterised by X-ray crystallography. Control of metal/ligand stoichiometry and structure is pursued by investigation of the effects on substitution patterns of the pyridine and aryl rings. Some distinct patterns emerged; (i) the 6-methyl position on the pyridine appears to be particularly important with regards to control of stoichiometry, although there are co-ligand effects; (ii) structures of the metal alkyl derivatives [Zr(n)(CH(2)R)(4-n)] are dominated by aromatic pi-pi stacking, even when bulky arene substituents are employed at. This leads to the complexes adopting a C(2v)-symmetric core; (iii) the amides [Zr(2)(NMe(2))(2)] have structures for which aromatic pi-pi stacking is unfeasible, and correspondingly C(2)-symmetric or similar structures are adopted. All the structural data presented is consistent with a trans influence order at zirconium Me(2)N > RCH(2) > py.

Polyolefin-polar block copolymers from versatile new macromonomers

A new metallocene-based polymerization mechanism is elucidated in which a zirconium hydride center inserts α-methylstyrene at the start of a polymer chain. The hydride is then regenerated by hydrogenation to release a polyolefin containing a single terminal α-methylstyrenyl group. Through the use of the difunctional monomer 1,3-diisopropenylbenzene, this catalytic hydride insertion polymerization is applied to the production of linear polyethylene and ethylene-hexene copolymers containing an isopropenylbenzene end group. Conducting simple radical polymerizations in the presence of this new type of macromonomer leads to diblock copolymers containing a polyolefin attached to an acrylate, methacrylate, vinyl ester, or styrenic segments. The new materials are readily available and exhibit interfacial phenomena, including the mediation of the mixing of immiscible polymer blends.

Chiral-at-metal organolanthanides: enantioselective aminoalkene hydroamination/cyclisation with non-cyclopentadienyls

Chiral non-racemic complexes [ML{N(SiMe2H)2}(thf)] (M = Y, La, H2L = salicylaldimine ligands derived from 2,2′-diamino-6,6′-dimethylbiphenyl) are found not to be effective catalysts for the intramolecular hydroamination of aminoalkenes, but new amino/phenoxide ligand designs without reducible functional groups led to long-lived and enantioselective catalysts.