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The Synthesis of Novel Inorganic Polymers Containing Boron Centers in the Main Polymer Chain
Dr. M. J. G. Lesley

1. Hydroboration polymerization of maleonitriledithiolate (MNT) derivatives

This project involves the derivatization of MNT and subsequent polymerization to yield the cyclodiborazane products
depicted in Scheme 1 (1 isomer shown). The products are air and water stable and the physical properties of these and
subsequent polymer derivatives will be examined with special emphasis on electronic conductivity and potential as
inorganic light emitting diodes.

2. Hydroboration polymerization of transition metal-MNT derivatives

Transition metal-MNT derivatives have been studied extensively. Some derivatives involving the platinum group metals
show tremendous potential for the preparation of super-conducting materials. As an extension of the polymerization shown
in Scheme 1, we will examine whether or not hydroboration polymerization of the cyano functionalities in the metal derivatives
will lead to polymeric precursors for the preparation of super-conducting and electro-optic materials. Alternatively, since
hydroborating reagents are known to react with numerous metal centers, we will also examine the synthesis of these
derivatives from polymers prepared in Scheme 1. For example, treatment of S-R bonds (where R = benzyl) with Na/NH₃
can be used to reform S-Na bonds. Treatment of these derivatives with metal halides should cross-link polymer chains
via incorporation of the metal fragments. These materials may have the potential for dissimilar rates of conduction along
the directions of the metal-MNT interaction and the polymer chain. This may lead to superior electro-optic properties for
device manufacturing.

3. The synthesis of pi-conjugated polymers containing Lewis acidic, 3-coordinate, boron centers

The polymeric materials discussed above incorporate anionic, 4-coordinate, boron centers in the polymer chain. These
polymers may react further if pendant B-H or B-Cl bonds are present to generate pi-conjugated derivatives. The generation
of 3-coordinate boron centers via removal of the B-N dative bonds and formation of B-C bonds (through condensation of
B-Cl with dilithium reagents or hydroboration of diynes with B-H bonds)

will be examined. The 3-coordinate boron centers are known to extend the pi-conjugation in related studies and provide
the potential for rare n-doped materials. One of the main disadvantages in this approach to new materials is the chemical
reactivity of the boron centers. To investigate the formation of stable conducting polymers we will also examine the use of
specific monomers in which intramolecular bonding can be used to stabilize the boron centers. Many of these monomers
can be designed from known synthetic routes involving the catalyzed diboration of alkynes. Two examples are shown in
Scheme 2. In these examples, polymerization will also be achieved using known reactions involving B-Cl and B-H bonds.

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