Phosphine-Borane Dehydrocoupling: The Synthesis of Tailored New Materials through Mechanistic Studies of Catalytic Processes.

Transition-metal-catalysed reactions the make or break C-C, C-H or C-X bonds are cornerstone in the synthesis of commodity/feedstock chemicals and fine-chemicals. The elucidation of mechanism for such processes has led to major breakthroughs of fundamental, commercial and societal importance (e.g. routes to new pharmaceuticals, polymer synthesis, the synthesis of new materials with exciting properties, more efficient and greener ways to construct new molecules). By contrast the development of analogous catalytic routes to prepare bonds between main-group elements is still nascent. This gap in knowledge/technology is remarkable given the potential that such routes would have for the synthesis of novel polymers, new materials, electronic devices as well as new organic methodology and the synthesis of biologically active molecules. Recently there has been intense interest in catalytic dehydrocoupling strategies for group 13/15 materials, prototypically H3B-NRRH and H3B-PRRH (R = alkyl, aryl, H) that are precursors for new hydrogen-delivery systems or novel polymeric materials. Group 13/15 polymers are relatively unexplored, yet are important as analogues of polymeric all-carbon systems that could potentially have technologically useful thermophysical, pre-ceramic and other useful materials properties. Remarkably, lacking is a unified mechanistic approach to the design of catalyst systems that allows for the bespoke production of such materials. In this project we will provide full mechanistic details for dehydrocoupling and use this knowledge to design, develop and implement catalyst systems that will generate new phosphine-borane (P/B) materials. Our goal is the targeted synthesis of well-defined novel monomeric, oligomeric and polymeric phosphine-boranes that will have significant potential for future technological applications.

The aim of the research described in this research proposal is to use fundamental studies to enable the development of highly efficient metal-catalyzed dehydrocoupling routes to polyphosphinoboranes, a novel class of inorganic polymeric materials that are isoelectronic with polyolefins. At the outset it is clear that this work offers the prospect of developing new materials with important potential uses and commercial applications. Moreover, as with any fundamental, exploratory research project, some of the most important developments are likely to be unforeseen at this stage. The work is therefore of potential long term benefit to UK plc through industry, government labs and spin-outs (as well as to academic science). The PDRA co-workers are also beneficiaries of this research as they benefit significantly in terms of professional and career development from a future employment perspective by participating in this collaborative and multifaceted project.


The synthesis of new materials which show potentially very useful properties, development of new catalytic techniques both specific to this project and, in a more general sense, the development and training of talented future scientific leaders are all measurable benefits that will arise from this research Many of the materials and properties targeted (e.g. fluoropolymers, new main group polymers, viscosity modifiers) are of broad industrial interest. AWE and Infineium have already indicated an interest in various aspects of polyphosphineborane materials should certain properties be demonstrated and they have contacted Weller and Manners to express this. Their letters of support are attached. Our experience indicates that for this type of fundamental, exploratory research project, setting up industrial collaborations is most sensibly performed once exceptional properties of interest are clearly demonstrated, as realistic specific potential uses can then be foreseen.

The development of new efficient catalytic techniques that not only allow new technologically important materials relevant to society to be made, but do this to order and with minimal waste, is of clear importance. This is important not only for the specific materials discussed herein, but also in a more general sense with regard to the fundamental underpinning science that can be applied to other areas.

It is envisaged that broad interdisciplinary scope and collaborative nature of the project, which involves catalysis, molecular and polymer synthesis, the use of materials and property characterization techniques and kinetic studies will give the postdoctoral workers exceptional training for their future careers. This is likely to be in industry or government labs (or, as an alternative, academia). These employers will also therefore be substantial beneficiaries from the training provided by the proposed research. The postdoctoral workers trained by performing the proposed research are likely to find an excellent future position. The Manners, Weller and Lloyd-Jones groups have an outstanding record in training personnel. Many research workers on leaving their groups enter academia or significant positions in industry or government labs.

The generation of intellectual property and spin-out company opportunities are realistic, particularly if new materials prove suitable as ceramic precursors, robust polymers or additives for various applications (i.e. viscosity modifiers). Manners has a strong track record in the intellectual property area involving setting up and implementing productive collaborations with industry and is involved with a start up company (Opalux) commercialising photonic crystal display devices based on materials developed in his group. It is also noteworthy that the Universities of Bristol and Oxford have an impressive record for the generation of highly inventive spin-off companies. Weller has recently been an inventor on a number of patent applications.