Olefin complexes 1120 INDEX

My first incursion into organo-transition metal chemistry occurred because of my interest in chemical bonding. How did olefins with no lone pair of electrons form coordinate bonds to metal atoms The position in 1941 can be read in Keller s review on olefin complexes 54). During the war years I was able to assemble a card index of all references to olefin complexes and I convinced myself that they should be formulated as chelate complexes of, for example, structure (VII) for Zeise s ion if chlorine could bridge metal atoms why should it not bridge carbon to a metal Nature rejected my letter on this topic as being... 

This technology has been utilized by BP Chemicals for the production of lubricating oils with well defined characteristics (for example, pour point and viscosity index). It is used in conjunction with a mixture of olefins (i.e., different isomers and different chain length olefins) to produce lubricating oils of higher viscosity than obtainable by conventional catalysis [33]. Unichema Chemie BV have applied these principals to more complex monomers, using them with unsaturated fatty acids to create a mixture of products [34]. 

Zirconium and hafnium complexes of an amine bis(phenolate) ligand with a THF side-arm donor have been shown to perform living polymerization of 1-hexene when activated with B(C6F5)3. The Zr catalysts (1) possess very high activities of 21 OOOgnunol cath. In neat olefin, the reaction is very exothermic and accompanied by various termination processes resulting in a higher polydispersity index than observed when the monomer is diluted in chlorobenzene. 

Since the measurement of on-line catalyst activity is difficult, we found it convenient to follow an on-line "reaction index" (RI), which is a selectivity ratio. The complex MTO reaction scheme can be presented schematically as A —> B —> C, where A represents methanol and DME, B - olefins, and C -aromatics and paraffins (Fig. 3). One particularly useful RI is the propane/propene ratio. Propene is the primary light olefin and propane represents paraffins. The propane/propene RI can be easily monitored by an on-line GC. We found that hydrocarbon selectivities correlate well with RI. For fixed hydrodynamics, it also correlates well with methanol conversion. 

However, until recently no complexes clearly showed interactions of single C-C bonds with M because of steric interference of the substituents on tetrahedral carbon and the presence of more accessible C-H bonds that can give competing agostic interactions. The first example of well-characterized agostic C-C interactions is present in a 14e titanium system (23).55 The saturated carbon C7 is only 2.293(7) A from Ti (and even less for , C6, and C8). Remarkably these carbons are closer to Ti than any of the bound olefinic carbons C4 and C5 (2.30-2.34 A) and Cp carbons, clearly indicative of several C-C bond interactions. The Ti-C2 distance of 2.579(7) A also indicates that this carbon is involved in the agostic C-C interactions, which are verified by DFT calculations to occur for C2-C7 and even more strongly for the C2-C3, C6-C7, and C7-C8 bonds. Bond indexes of 0.168 for the Ti-C7... 

Since the transport of a small molecule through a fixed carrier membrane depends largely on the kinetics, reversibility and affinity of the small molecule to the metal complex carrier, the transport properties of a small molecule are a good index for the activity of a metal complex in a macromolecule. Therefore, the following sections give a brief review of facilitated olefin and oxygen transport. 

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