Professor Dean M. Giolando's Faculty Page

Inorganic- Organometallic Chemistry:
Synthetic, structural analysis and reactivity studies on compounds containing the main group elements and complexes at the transition metal main group interface.

My research program addresses several problems in main group and transition metal main group chemistry. Initial phases of the research topics are synthetic and structural in nature. Upon understanding the synthesis and prop- erties of these classes of compound subsequent stages comprise detailed reactivity studies with the goal of passivating the preparation of semiconducting materials.

Main Group Compounds as Precursors to Materials. I am particularly interested in projects that deal with the syn- thesis and characterization of main group compounds as precursors to main group materials (e.g., GaAs, SiGe, CdTe, CaInSe2, and ZnSnP2). Synthetic studies are motivated by the lack of information on the synthesis and reactivity of main group compounds containing the heavier elements as well as nonalkyl substituents. The objective is to gain knowledge and insights which will allow selective syntheses of a broad base of main group compounds containing elements from groups 12 to 16.

Further goals are centered on the reaction chemistry of main group cage compounds. Initially, the reactivity of the substituents on the main group atoms will be characterized. Conceivably, situations will arise where substituents can be exchanged without skeletal rearrangements; i.e., metastable compounds are isolable and characterizable. Kinetic products are of interest because of inherent ring and angle strain should provide reactivity patterns that may not otherwise be available (e.g., insertion reactions).

Explorations of the Synthetic Utility of the Tin Telluride Bond. Tin tellurides are potentially a useful class of compound for which reactivity studies are rare. One possible application for tin telluride chemistry is the preparation of tellurium-based organic metals, an area that has been expanding at an increasingly rapid pace. Within the past fifteen years conducting salts based upon tetrathiafulvalene and metal dithiolene derivatives have made very important contributions to the area of one-dimensional conductors. However,while selenium-based compounds have provided several examples of conducting materials, the tellurium analogs are nearly nonexistent. Tellurium analogs are being soughtduetotheexpectation of enhanced stability and increased conductivity of the quasi-one-dimensional material.

The major hurdle encountered in attempts to prepare tellurium-based materials has been the preparation of appropriate organotelluride precursors. One aim of this program is to investigate new synthetic methodologies for the preparation of tetratellurafulvalene derivatives as well as arene ditellurides. These classes of compound will likely afford novel tellurium-based organic metals with properties that are superior to those of the analogous sulfur(selenium)-based salts. The organotelluride precursors used in these studies are also useful in prepararing novel tellurium- containing main-group and transition- metal complexes, some of which are expected to give semiconducting and superconducting materials.

The synthetic methodology introduced above lends itself to applications for the preparation of tellurium-based materials. The tin group has the ability to act as a protecting group for tellurium while maintaining highly nucleophilic character at tellurium but while containing a relatively stable, yet controllable reactive, Te-Sn Bond This strategy allows the formation of a single bond to tellurium without occurrence of further reactions at tellurium (this behavior contrasts with reagents such as Na2Te) Having formed a variety of Te-heteroatom bonds the TeSn bond can be subsequently cleaved in two ways: (1) reaction with LiMe via a lithiation reaction, or (2) reaction with a labile main-group or transition-metal halide.