Projects / Programmes
Reactions of N-heterocyclic carbenes with silicium compounds
| Code |
Science |
Field |
Subfield |
| 1.04.04 |
Natural sciences and mathematics |
Chemistry |
Organic chemistry |
| Code |
Science |
Field |
| P395 |
Natural sciences and mathematics |
Organometallic chemistry |
| Code |
Science |
Field |
| 1.04 |
Natural Sciences |
Chemical sciences |
N-heterocyclic carbenes, polyhedral silsesquioxanes, siloxanes, silanes, imidazolium salts,
Researchers (1)
| no. |
Code |
Name and surname |
Research area |
Role |
Period |
No. of publicationsNo. of publications |
| 1. |
28565 |
PhD Matjaž Koželj |
Chemical engineering |
Head |
2011 - 2013 |
95 |
Organisations (1)
| no. |
Code |
Research organisation |
City |
Registration number |
No. of publicationsNo. of publications |
| 1. |
0104 |
National Institute of Chemistry |
Ljubljana |
5051592000 |
21,527 |
Abstract
The proposed project tries to combine the two fastest-growing branches of research in organic/organometallic chemistry, which have not been very much involved in the existing research work of Slovenian scientists. Chemistry of organic silicon compounds in Slovenia was limited to a few examples of sol-gel processing of alkoxysilanes. On the other hand, the chemistry of N-heterocyclic carbenes (NHC) has been almost completely ignored. Silicon compounds became more and more important for the preparation of special materials, which are tailored on molecular scale so this kind of project could be very strategic in order to support novel technologies. The knowledge, which will be gained on the NHC compounds during this project could be further exploited for the preparation of transition metallic complexes, which are important catalysts for organic transformations. This ensures a possible continuation of this project.
The basic idea is to investigate the use of N-heterocyclic carbenes as potential catalysts in transformations involving reactions on silicon center. I estimate that carbenes could activate silicon compounds, so they are more reactive and the reaction proceeds faster, resulting in shorter conversion periods. N-heterocyclic carbenes can act as a strong base, as well as strong nucleophiles, these two features are critical in ensuring sufficient catalytic efficiency in reactions on silicon.
The first objective of the project is to examine the suitability of N-heterocyclic carbenes in preparation of polyhedral silsesquioxanes, that is to examine how and if carbenes promote condensation, decondenzation and recondenzation of trifunctional silanes (T-siloxanes).
The second objective is to clarify the mechanism of catalytic action / activation of silicon derivatives, especially trifunctional silanes with N-heterocyclic carbenes. This includes the preparation and isolation of stable complexes of N-heterocyclic carbenes with siloxane silicon compounds. A particularly interesting area of this study research is the stability of 1.3-disubstituted imidazolium silanolates, which could serve as stable precursors for in situ preparation of free carbenes.
Another aim is to check the interactions between N-heterocyclic carbenes and other silicon compounds, especially those which have significant technological importance. The crosslinking/hardening of siloxanes polymers could be catalyzed by N-heterocyclic carbenes or their cryptoforms.
The project leader/applicant has extensive experience in preparing organic silicon compounds, especially with alkoxysilanes (PhD thesis). NHCs are in many cases closely related to imidazolium ionic liquids, which were also subject to that thesis. Therefore, this project is conceived as a logical follow-up to surveys conducted during the doctoral program. The reason for the continuation of research in the field of silicon chemistry are certainly excellent and interesting results that have been achieved in this area in the past because they were implemented into two inventions in the world's important industrial manufacturing processes.
Significance for science
The project “Reactions of N-heterocyclic carbenes with silicium compounds” was marked as a basic project, as it tried to answer to some very interesting questions about the reactivity of both silicon compounds as well as N-heterocyclic carbenes. These two branches of the chemistry experienced a boom-progress in the last 10–20 years and are still, in my opinion, two of the fastest growing in the field of organic/organometallic chemistry. This is especially true for N-heterocyclic carbenes, which changed from obscure elusive intermediates in reactions into excellent ligands for the preparation of catalytic organometallic complexes. Moreover, free carbenes are excellent catalysts for the synthesis of organic (i.e. carbon) compounds. It was shown many times that free carbenes catalyze some organic reactions, particularly reactions of carbonyl systems (benzoin condensation catalyzed by thiazol-2-ylidenes, synthesis of polyesters by imidazole carbenes). Silicon chemistry is not a popular research field like pure organic synthesis, so it offers much more opportunities for interesting research. Silicon possesses the possibility of forming stable (isolable) hypervalent complexes so its chemistry has broader spectrum of reactions than the carbon, which is in the majority of compounds only tetravalent. This ability (coordination higher than 4) is the basis for many conversions of silicon compounds (including sol-gel processes), which are of great importance in technology of the preparation of materials. The knowledge about the chemical properties of silicon compounds suggests that carbenes could act as catalysts for the conversion of silicon compounds. I estimated that this area of carbene chemistry is still underdeveloped and therefore offers an extremely wide fundamental research field of interactions between carbenes and silicon and therefore this theme should be explored as soon as possible, so this was reason for proposing such research project top the Agency The project was set up primarily to highlight the problem of synthesis of polyhedral silsesquioxanes through carbene catalysis. I tried to explain these conversions by a series of experiments and to show how the carbenes really catalyze the process of condensation and decondensation of siloxane compounds. This issue has not been clarified yet. Scientists reported only catalytic activity in polymerization of difunctional siloxanes, but also there they have not been able to explain catalysis; monofunctional and trifunctional silanes are completely unexplored. The results of this project are significant contribution to understanding of those reactions. The investigation of the carbene hypervalent silicon complexes with alkoxysilanes seems to be very interesting for the professional audience. A combination of two very progressive areas of chemical research ensures the high impact of the results, so I think that approval of this project was a reasonable and good decision.
Significance for the country
It is unrealistic to expect from a basic project a great influence on industrial processes. But still, some findings were patented, the IP protected and so prepared for transfer of the knowledge into production lines; but no interest was shown from potential users of that technology. The project could not provide a direct rapid technological breakthrough, but as was shown in research work during the PhD project of the project leader, silicon compounds are allowed remarkable progress in the technology of preparation of spectrally selective coatings and corrosion protection of solar absorbers. Despite many experiences of the project leader in the field of technology transfer, the results remained only as scientific publication, so the impact of these results on development of industry is negligible in Slovenia as well in whole world. However, the aim of the project were not patents and improvement of industry but rather fundamental knowledge and therefore project has impact on science of silicon and N-heterocyclic carbene chemistry which is more evident internationally than in Slovenia, where continuation of this project dealing with silicon chemistry, ionic liquids and N-heterocyclic carbenes was not recognized as worthy for further financing. I will try to collaborate on this topic with foreign scientists in the frame of COST action CM 1206 – Exchange on Ionic Liquids, what could contribute to higher recognition of National Institute of Chemistry.
Most important scientific results
Annual report
2011,
2012,
final report,
complete report on dLib.si
Most important socioeconomically and culturally relevant results
Annual report
2011,
2012,
final report,
complete report on dLib.si
