Transition Metal - Main Group Multiple Bonding

With the support of the Chemical Synthesis (SYN) program in the Division of Chemistry, Professor T. Don Tilley of the University of California, Berkeley will study new structures and reactions of chemical compounds that incorporate both a transition metal and silicon. Discoveries in this area are expected to provide new compounds and chemical transformations that accelerate emerging applications of silicon-based materials, which include silicone polymers, adhesives, lubricants, and semiconductors.

A primary objective is the study of a little understood type of chemical compound that features silicon atoms bonded only to metal centers. Such compounds are expected to exhibit properties that have yet to be thoroughly explored, but promise to aid the improvement of industrial processes. In addition, this program prepares graduate and undergraduate students for careers in science by providing a research environment that fosters critical thinking and problem-solving skill development.

There is an important educational-outreach component that include work with transfer students to ease their entry into the Berkeley program. Students will participate in outreach programs that include hosting high school students and engaging with local elementary schools to teach basic scientific principles through interactive lessons. There is a long standing strong record of training of research students; this training includes preparing students to work with challenging chemicals and reagents.

Complexes that formally possess a multiple bond between a metal and silicon, such as silylene complexes (LnM=SiRR'), have attracted considerable interest over the years, for their assumed or established role in catalytic processes such as silylene-transfer or hydrosilylation. The focus of this project will center on development of a better understanding of chemical properties associated with multiple bonding, with three primary aims designed to (1) expand the knowledge base for metal silylene complexes formally possessing M=Si double bonds, (2) explore a new class of compounds – molecular silicide complexes with M=Si=M cores, and (3) develop informative, periodic relationships to metal-element multiple bonds involving the heavier group 14 elements germanium, tin, and lead.

A central objective will be establishing principles that govern formation and transformations of the molecular silicides, containing metal-ligated silicon atoms. For comparison, solid-state metal silicides are of immense technological importance as catalysts that make and break bonds to silicon, as in the direct process for the synthesis of organosilanes from elemental silicon.

Despite the technological importance of transition-metal silicides, little is known about their reaction mechanisms and this knowledge gap makes it difficult to design processes that utilize silicides as synthetic intermediates. Molecular silicides should be amenable to mechanistic investigation and development of homogeneous transformations of silicon compounds.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.