SURFACE

Title

Thermal and photochemical reactions of large metallaborane clusters and functionalizations of boron nitride nanosheets

Author

Pei Ma

Date of Award

8-2013

Degree Type

Dissertation

Embargo Date

2-3-2015

Degree Name

Doctor of Philosophy (PhD)

Department

Chemistry

Advisor(s)

James T. Spencer

Keywords

Boron nitride nanosheets, Carborane, Crystal structures, Functional derivatives, Metallaborane, Photochemistry

Subject Categories

Chemistry

Abstract

The thermal and photochemical pathways of several metallaborane compounds and the functionalization of boron nitride nanosheets have been investigated. The nanosheets have potential applications in Dye Sensitized Solar Cells.

Chapters 1 and 3 describe the thermal and photochemical pathways for two metalladecaboranes, [nido -6-Mn(CO) ₃ B ₉ H ₁₃ ][NMe ₄ ] (1.1) and [6-C₅Me₅-nido-6-RhB₉H₁₃] (3.1). Isomerization or cage closure reactions were observed depending on the reaction conditions and the transition metal employed. Characterized products include the first nido-5 metalladecaborane and a hypercloso-metalladecaborane containing a group 7 transitional metal, compound 1.3 and 1.4, respectively. Other findings include the facile acid catalyzed cyclic oxonium functionalization of complex 1.1, the role of complex 3.1 as the catalyst for the [2+2+2] cycloadditions of terminal alkynes, and the formation of hypercloso-rhodadecaborane 3.3 which is the first hypercloso-metalladecaborane containing the metal rhodium.

Chapter 2 describes investigations of the photochemical reactions between metallaboranes and unsaturated molecules. The complex 1.1 was found to photoreact with both terminal and internal alkynes to afford the carborane with general formula [7-R-8-R'-7,8-nido-C₂B₉H₁₀][NMe₄] (2) in good yield. This represents a novel method for generating the substituted nido-C₂B₉ complex. Besides alkynes, the investigation of the photoreactions of other unsaturated species with the complex 1.1 were found to generate the [arachno-B₉H₁₄]- (2.4) and [nido-B₉H₁₂]- (2.5) anions in different relative ratios, depending on the nature of the unsaturated molecules. The complex 1.1 was also found to act as an efficient catalyst for isocyanate cyclodimerization under photo-irradiation conditions, representing the first example of a metallaborane complex to catalyse the cyclodimerization of isocyanate.

In Chapter 4, an effective and simple noncovalent functionalization and solubilization of boron nitride nanosheets (BNNSs) has been achieved by using polythiophene or polyvinylpyrrolidone as a functionalization polymer with BNNSs. The BNNSs form strong π-π stacking interactions with the polythiophenes and were found to act as a bandgap tuning tool for polythiophene derivatives. A BNNS-polythiophne-TiO₂ hybrid nanomaterial was achieved by the covalent binding between TiO₂ nanoparticle surfaces and the BNNS-polythiophene unit containing a carboxylic acid functional group. This nanomaterial was then further incorporated into a Dye Sensitized Solar Cells (DSSCs) and the observed enhancement of the performance of the cells is discussed.

Access

Open Access

Recommended Citation

Ma, Pei, "Thermal and photochemical reactions of large metallaborane clusters and functionalizations of boron nitride nanosheets" (2013). Chemistry - Dissertations. Paper 200.
http://surface.syr.edu/che_etd/200