C.-G. Wu

Alkyne competition in the benzannulation reaction with chromium carbene complexes.

The benzannulation reaction of Fischer carbene complexes is investigated under conditions where the reaction of the carbene complex is occurring in the presence of two different alkynes. A series of competition experiments are examined where the effects of various structural factors are explored by pitting 10 different carbene complexes with 11 different alkynes. Terminal alkynes will react selectively over internal alkynes in all cases examined including both aryl and alkenyl complexes. Aryl carbene complexes with methoxy substituents do not give quite as high selectivity for terminal alkynes over internal alkynes ( approximately 95:5) as do isopropoxy substituents (>99:1), whereas most alkenyl complexes give high selectivity with both substituents (>99:1). Competition experiments between two different terminal alkynes or between two different internal alkynes did not result in anything more than very modest selectivities at best ( approximately 2:1). Excellent selectivities were realized between two different terminal acetylenes if one of the terminal acetylene was protected with a trimethylsilyl group. Finally, it was demonstrated that the high selectivities between terminal and internal alkynes can be utilized in the reaction with molecules that contain both types of alkyne functions.

Conjugated Polymers in Layered Hosts: Formation of Emeraldine Salt and Polyfuran in FeOCl

Electrically conducting polymers have received a great deal of attention due to their promising electrical properties and potential applications1, 2. Our understanding of the structure of these systems is still fragmentary due to their quasi-crystalline nature and insolubility in common organic solvents. Important structural problems associated with single chain and their macromolecular aggregation remain to be solved. The systematic control and modification of their physical, structural and electronic properties is an active area of research. Goals include the optimization of the charge transport properties and the better understanding of the relationship between electronic and lattice structure.

Intercalation Of Layered V 2 O 5 Xerogel With Polymers

The intercalation properties of the layered V 2 O 5 xerogel towards conductive polymers are described. The systems intercalated with polyaniline show post-intercalative redox polymerization caused by ambient oxygen to give products with enhanced conductivity. For the first time the role of oxygen in this intercalation reaction has been unequivocally identified. We also report the synthesis and some properties of a new intercalation compound in which the guest species is poly(ethylene oxide), an insulating polymer.