Final Report Summary - LE-PKR (Ligand Engineering for Pauson-Khand Reactions) This project, entitled "Ligand Engineering for the Pauson-Khand Reaction", sought to develop an efficient method for the preparation of compounds with 5-membered carbon cycles (cyclopentanes). This motif is ubiquitous in natural products, drugs and all sort of chemical specialties, usually embedded in intricate structures of difficult access by human methods. Therefore, their preparation by chemical synthesis starting from simple and readily available materials is still a subject of intensive research.The main goal of the project was to find a faster version of the Pauson-Khand reaction, a method which has been known for decades and is often cited in textbooks but which does not comply with the modern criteria of efficiency, utility and versatility. Our approach was based on modifying the cobalt derived organometallic species used for this purpose to turn it into faster, eventually more versatile catalysts.We have succeeded in preparing different catalysts for the Pauson-Khand reaction with novel structures, some of which showed certain acceleration with regards to traditional systems. Although the catalytic activities achieved do not represent a significant advantage in practical terms, our research has allowed us to identify mechanisms by which the reaction is accelerated. Future prospects include implementing this knowledge in the design of new and improved catalysts.The CIG action has been highly beneficial for the reintegration of the fellow into the Spanish scientific system. He has been able to attend diverse meetings, including the National Meeting of the American Chemical Society held in San Diego (CA) in March 2012 where he presented his latest progress in this project. During his stage at the Institute for Research in Biomedicine (IRB Barcelona) he has co-authored several publications including his first research paper as a corresponding author. This certainly represents a leap forward in the fellow's academic career. Most importantly, having received independent funding from the EU has been critical for securing a contract from the Spanish Government under the Ramon y Cajal program, which will allow him to develop his career as an independent researcher during the following 5 years.