X-ray crystallography and its application in the design, synthesis and characterisation of novel α-diimine complexes for use as polymerisation catalysts

The synthesis and characterisation of a selection of asymmetric and symmetric a-diimine ligands are described, including their single crystal X-ray structures and those of the imino-ketone intermediates used in their synthesis. The coordinated Fe(II) dichloride complexes of a series of a-diimine ligands used as ATRP catalysts are reported, along with the crystal structure of [FeCl2(2,6-diisopropylphenyl)2DABH2] and [FeCl2(c-hexyl)2DABPh2]. The isolation of high molecular weight polyethylene derived from (2-isopropylphenyl)2DABPh2 and MMAO in an initial attempt to react the tentatively formed [FeCl2(2-isopropylphenyl)2DABPh2] led to the development of AlCl3 a-diimine chemistry and the synthesis of a range of novel AlCl3 coordinated (2,6-diisopropylphenyl)2DABH2 complexes and 4,4’-m2{(N,N’-bis(2,6-diisopropylphenyl)- 2,2-dichloro-1,3,2-diazaalane}. The use of AlCl3 also led to the structure determination of [{ClSiMe2OAlCl2}2] obtained from a room-temperature depolymerisation reaction for silicone grease with AlCl3. The application of the a-diimine library developed to palladium dichloride, and the structure determination of a range of novel palladium dichloride complexes are also presented, with relation to structural changes to the a-diimine upon coordination. These trends are followed into the formation of monomethylated palladium chloride and Brookhart type ([PdMe(NCCH3)a-diimine]BAF) pro-catalyst complexes. A range of Brookhart type pro-catalyst were studied in relation to the effect of altering steric bulk at the a-carbon, H < Me < Ph on polymerisation activity. Progress made in developing low cost hardware for X-ray diffraction environmental control is described as well as the use of informatics to design and implement of an in-house structural database, accessible via a world-wide-web portal using SSL technology.