Norbomene fluorinated

The course of addition reactions of ROH-XeF2 to alkenes has been elucidated using norbomene, 2-methylpent-2-ene and hex-l-ene as model substrates. It turned out that the alkoxyxenon fluoride intermediates (ROXeF) can react either as oxygen electrophiles (initially adding alkoxy substituent) or as apparent fluorine electrophiles (initially adding fluorine), depending on the reaction conditions. Simple addition of poorly nucleophilic alcohols to norbomene was also observed in certain instances. Selectivity between the various reaction pathways (simple fluorination, alkoxyfluorina-tion, or alcohol addition) proved to be sensitive to various reactions conditions, especially solvent, temperature, and catalyst.27... 

Additions occur more easily if a carbanion with resonance or inductive stabilization is formed in the addition. Thus, fulvenes are very reactive, vinylsilanes and highly fluorinated alkenes somewhat less so. Styrene, 1,3-dienes, and enynes are more reactive than isolated alkenes, and Grignard reagents may be used to initiate anionic polymerization of styrenes, dienes, and acryhc monomers. Strained alkenes such as norbomenes and cyclopropenes are also more reactive. Examples of additions facilitated by resonance or substitution are shown in Scheme 8. 

The absorbance of a fluorine containing monomer at 157 nm is influenced by the position of the F atom in the molecule. For norbomene, for example, one of the commonly encountered monomers in polymers designed for 157 nm lithography, the absorbance varies greatly depending on the position of the substituting F atom. When two F atoms are introduced in a molecule, the absorption is reduced even more [62]. 

ROMP of norbomenes substituted with various fully fluorinated alkyl substiuents (Perez 1988),... 

Figure 1. Examples of fluorinated norbomenes investigated by classical ROMP in the Durham group.

The second step involved the ROMP of the functionalised PEO macromer using the well-defined Schrock (hexa-fluorinated) or Grubbs initiating complexes. Each initiator had a metal core (molybdenum or ruthenium) with bulky ligands that controlled the approach and co-ordination of the reactive carbene bond to the double bond of the norbomene group... 

Other experimental 157-nm resists can be considered to be derived from 193-nm CA resists. The homopolymer poly(HFIPA-norbomene) has an optical density of 1.8/)nm (130). First used in 193-nm resist polymers (131), HFIPA-norbomene monomer can be incorporated into cyclic olefin polymers prepared via organometalUc catalysis, and can be copolsrmerized with vinyl monomers such as acrylates or fluorinated acrylates using standard free-radical polymerization to give products with optical densities of less than 3/)um (Fig. 18, lower structure) (132,133). Still other fluorinated monomers can be employed in 157-nm resists, and resist systems based on polymers of fluorinated olefins and vinyl alcohols have been described (134,135). In general, it appears that incorporation of fluorine compromises the etch resistance of resists when compared with their hydrocarbon analogues (136). 

Barnes DA, Benedikt GM, Goodall BL, Huang SS et al. (2003) Addition polymerization of norbomene-type monomers using neutral nickel complexes containing fluorinated aryl ligands. Macromol 36 2623-2632... 

A class of fluorinated Grubbs second-generation alkene metathesis catalysts was recently prepared (Scheme 7.20) [31]. Compared with their non-fluorinated analogs, fluorinated Grubbs metathesis catalysts catalyzed the ring-opening metathesis polymerization of norbomene with almost identical rates. It is noteworthy that... 

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