Doctoral Defense - Dmitrii Razinkov

Doctoral candidate:
Dmitrii Razinkov

Title of thesis:
Reactivity of Phosphinoyldithioformate Molybdenum-Sulfur Complexes

Opponents:
Dr. Rosa María Llusar Barelles, Professor of Physical Chemistry, Jaume I University, Spain
Dr. Mar Masson, Professor at the Faculty of Pharmaceutical Sciences, University of Iceland

Advisor:
Dr. Sigriður Gudrun Suman, Professor at the Faculty of Physical Sciences, University of Iceland

Other members of the doctoral committee:
Dr. Gissur Örlygsson, Project Manager, Genis hf, Reykjavik, Iceland
Dr. Águst Kvaran, Professor Emeritus at the Faculty of Physical Sciences, University of Iceland

Chair of Ceremony:
Dr. Birgir Hrafnkelsson, Professor and Head of the Faculty of Physical Sciences, University of Iceland

Abstract:
The design of an effective catalyst is a challenging task. The ideal catalyst should possess high activity, be selective toward desired products, and have exceptional stability under demanding conditions. Non-rigid behavior that accommodates the change in coordination geometry around the metal center is a desirable property for an effective catalyst. Dimerization is a common issue that can occur in a catalyst system, leading to the formation of inactive species and decreasing the catalyst efficiency. Dinuclear molybdenum-sulfur complexes with non-rigid bulky phosphinoyldithioformate ligands with aryl groups can increase the performance of the catalysts, preventing common obstacles like dimerization. Ligands with non-rigid behavior that accommodate the change in coordination geometry around the metal center may facilitate catalysis, where it can minimize deactivation reactions based on unsaturated coordination spheres around the metal center. Two types of dinuclear molybdenum-sulfur complexes with phosphinoyldithioformate ligands 2:1 complexes (with two phosphinoyldithioformate ligands) and 1:1 complexes (with one phosphinoyldithioformate and disulfide ligands) were synthesized and fully characterized including X-ray crystal structure and NMR spectroscopy, mass spectrometry and elemental analysis. These complexes were synthesized with the aim of studying them in industry-related sulfur atom transfer (SAT), where sulfur atoms are inserted into metal-sulfur ligands, followed by the expulsion of elemental sulfur. Synthesized molybdenum-sulfur complexes were used as catalysts for the synthesis of sustainable biobased furanic polyester, polyethylene furanoate (PEF), which is a promising alternative for food packaging to replace fossil-based polyethylene terephthalate (PET). Additionally, chemical recycling of PEF employing molybdenum-sulfur complexes through mild glycolysis was tested to address the "end-of- life" of PEF. Complexes with disulfide and phosphinoyldithioformate ligands were tested in converting toxic cyanide to nontoxic thiocyanate to compare with previously reported structurally similar complexes. They showed high conversion after short reaction times.

About the doctoral candidate:
Dmitrii Razinkov conducted his studies in Inorganic Chemistry at the University of Iceland under the guidance of Professor Sigríður G. Suman. He received a bachelor’s degree in Chemistry in 2014 from Southwest State University in Kursk, Russia. He worked on the reactivity of 4-substituted 1,2,4-triazines. He moved to Iceland in 2015. Dmitrii finished the program “Icelandic as a Second Language, for Practical Purposes” in 2016 and studied Icelandic at the BA program “Icelandic as a Second Language” at the University of Iceland and completed one year. After several years of wandering, faith brought him to Prof. Sigríður G. Suman’s lab, and he completed his master’s degree in 2020 in the synthesis and characterization of phosphynoyldithioformate complexes with molybdenum and continued that work under the guidance of Prof. Sigríður G. Suman. During his PhD studies, Dmitrii presented the results of his work at several conferences, received several grants, a Science and Innovation Award from the University of Iceland, went on an EU COST collaboration at the University of Aveiro, Portugal, where he worked on synthesis and recycling of sustainable polymers and has been a beloved assistant teacher at the University of Iceland.