Main-group element compounds possessing multiple reaction centers - Systems between cooperativity, synergy and emergence

• Applicant: Professor Dr. Robert Kretschmer, since 4/2019
• Subject Area: Inorganic Molecular Chemistry - Synthesis and Characterisation
• Term: from 2017 to 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 358651443

• Final Report Year: 2025

Final Report Abstract

The project was centred on cooperative or synergetic effects as well as emergent effects originating from polynuclear environmentally benign main-group element compounds. In detail, compounds in which a ligand frames two atoms of either aluminium, calcium, gallium, germanium, magnesium, silicon, or tin belonged to the primary focus of the project. Due to similarities of zinc with group 2 elements and some difficulties in obtaining the dinuclear heteroleptic group 2 complexes, zinc complexes have additionally been investigated. The project was divided into three subprojects, i.e.: i) Bond activation by oxidation-state invariant earth alkaline and group 13 compounds, ii) Multiple bond activation using low valent group 14 compounds, and iii) heterodinuclear group 2, 13 and 14 compounds. Considering the associated objectives and the overall aim of the Emmy-Noether program, that is the appointment to a permanent professorship, the project was fully successful. 30 publications in peer-reviewed journals appeared so far and several more publications are expected to be submitted in future. Furthermore, 7 PhD students and 2 postdoctoral researchers have been trained during the project. In addition to the original aims, new research directions have been opened up due to unexpected results. This is for example well illustrated by the finding of a dinuclear electron-precise aluminium complex with a quantum yield near unity, which might be used in light-emitting diodes in the future. Following these pioneering results, research on dinuclear complexes for the utilization in organic light emitting diodes (OLEDs) and/or organic solar cells has become a very important research area of the group.

Publications

• Dinuclear Aluminum Halide Complexes Based on Bis(β-diketiminate) Ligands: Synthesis, Structures, and Electrochemical Characterization. Inorganic Chemistry, 58(23), 16302-16311.
  Desat, Marcella E. & Kretschmer, Robert
  
• Facile oxidative addition of O2 and S8 by an indium bis(carbene) analogue. Dalton Transactions, 48(48), 17718-17722.
  Desat, Marcella E. & Kretschmer, Robert
  
• Ligands with Two Monoanionic N,N‐Binding Sites: Synthesis and Coordination Chemistry. Chemistry – A European Journal, 26(10), 2099-2119.
  Kretschmer, Robert
  
• Synthesis and Structures of Dinuclear Aluminum Complexes Based on Bis(β‐diketiminate) Ligands. Zeitschrift für anorganische und allgemeine Chemie, 646(13), 625-630.
  Desat, Marcella E. & Kretschmer, Robert
  
• Cooperative Bond Activation by a Bimetallic Main-Group Complex. Journal of the American Chemical Society, 143(1), 142-148.
  Kysliak, Oleksandr; Görls, Helmar & Kretschmer, Robert
  
• Cooperative H–X Bond Activation by Electron‐Precise Aluminium and Gallium Compounds Incorporating β‐Diketiminate Ligands. European Journal of Inorganic Chemistry, 2020(17), 1624-1630.
  Hitzfeld, Patrick S. & Kretschmer, Robert
  
• C–F bond activation by pentamethylcyclopentadienyl-aluminium(i): a combined experimental/computational exercise. Chemical Communications, 56(57), 7865-7868.
  Kysliak, Oleksandr; Görls, Helmar & Kretschmer, Robert
  
• Ditopic bis(N,N′,N′-substituted 1,2-ethanediamine) ligands: synthesis and coordination chemistry. Dalton Transactions, 49(39), 13818-13828.
  Rösch, Andreas; Herzog, Christoph M.; Schreiner, Simon H. F.; Görls, Helmar & Kretschmer, Robert
  
• Magnesium bis(amidinate) and bis(guanidinate) complexes: impact of the ligand backbone and bridging groups on the coordination behaviour. Dalton Transactions, 49(37), 13072-13082.
  Rösch, Andreas; Schreiner, Simon H. F.; Schüler, Philipp; Görls, Helmar & Kretschmer, Robert
  
• Salt metathesis as an alternative approach to access aluminium(i) and gallium(i) β-diketiminates. Dalton Transactions, 49(19), 6377-6383.
  Kysliak, Oleksandr; Görls, Helmar & Kretschmer, Robert
  
• Syntheses of Bis(N-heterocyclic carbene)s and their application in main-group chemistry. Journal of Organometallic Chemistry, 918, 121289.
  Röther, Alexander & Kretschmer, Robert
  
• Synthesis and Coordination Chemistry of 3,4-Ethylene-Bridged 1,1,2,5-Tetrasubstituted Biguanides. Inorganic Chemistry, 59(5), 2733-2746.
  Dehmel, Maximilian; Vass, Valentin; Prock, Lukas; Görls, Helmar & Kretschmer, Robert
  
• Calcium and Magnesium Bis(β-diketiminate) Complexes: Impact of the Alkylene Bridge on Schlenk-Type Rearrangements. Inorganic Chemistry, 60(7), 5310-5321.
  Rinke, Philipp; Görls, Helmar & Kretschmer, Robert
  
• Catalytic Activity of Various β‐Diketiminate Zinc Complexes toward the Ring‐Opening Polymerization of Caprolactone and Derivatives. Macromolecular Chemistry and Physics, 222(18).
  Köhler, Moritz; Rinke, Philipp; Fiederling, Kevin; Görls, Helmar; Ueberschaar, Nico; Schacher, Felix Helmut & Kretschmer, Robert
  
• Dinuclear Chlorotetrylenes of Silicon, Germanium, and Tin Based on a Backbone‐Bridged Bis(amidine). European Journal of Inorganic Chemistry, 2021(46), 4806-4811.
  Dehmel, Maximilian; Wünsche, Marius A.; Görls, Helmar & Kretschmer, Robert
  
• Mono- and Dinuclear Aluminium Complexes Derived from Biguanide and Carbothiamide Ligands. Inorganics, 9(7), 52.
  Dehmel, Maximilian; Görls, Helmar & Kretschmer, Robert
  
• Synthesis, characterization, and reactivity of group 13 hydride complexes based on amido-amine ligands. Dalton Transactions, 50(24), 8434-8445.
  Dehmel, Maximilian; Köhler, Angelina; Görls, Helmar & Kretschmer, Robert
  
• Synthesis, structure, and catalytic activity of dinuclear aluminium bis(amidinate) and bis(guanidinate) complexes. New Journal of Chemistry, 45(2), 972-981.
  Rösch, Andreas; Seifert, Fabian; Vass, Valentin; Görls, Helmar & Kretschmer, Robert
  
• A Highly Fluorescent Dinuclear Aluminium Complex with Near‐Unity Quantum Yield**. Angewandte Chemie International Edition, 61(17).
  Portwich, Flavio L.; Carstensen, Yves; Dasgupta, Anindita; Kupfer, Stephan; Wyrwa, Ralf; Görls, Helmar; Eggeling, Christian; Dietzek, Benjamin; Gräfe, Stefanie; Wächtler, Maria & Kretschmer, Robert
  
• A Planar Five‐Membered Aromatic Ring Stabilized by Only Two π‐Electrons. Angewandte Chemie International Edition, 61(31).
  Kysliak, Oleksandr; Schreiner, Simon H. F.; Grabicki, Niklas; Liebing, Phil; Weigend, Florian; Dumele, Oliver & Kretschmer, Robert
  
• Bond Activation by a Bimetallic GaIComplex: Avenue to Intermetallic Compounds. Organometallics, 42(1), 72-80.
  Helling, Christoph; Farmer, James C.; Wölper, Christoph; Kretschmer, Robert & Schulz, Stephan
  
• A molecular aluminium fulleride. Chemical Communications, 59(51), 7923-7926.
  Lawrence, Samuel Ray; Rüffer, Tobias; Stasch, Andreas & Kretschmer, Robert
  
• A tetranuclear magnesium hydride cluster with a four-coordinate hydride in near square-planar geometry. Chemical Communications, 59(49), 7627-7630.
  Seifert, Fabian; Görls, Helmar; Kupfer, Stephan & Kretschmer, Robert
  
• Anion‐Dependent Reactivity of Mono‐ and Dinuclear Boron Cations. Chemistry – A European Journal, 29(65).
  Röther, Alexander; Farmer, James C.; Portwich, Flavio L.; Görls, Helmar & Kretschmer, Robert
  
• Synthesis and Characterization of Magnesium-Hydride Complexes with Alkylene-Bridged Bis(β-diketiminate) Ligands. Organometallics, 42(16), 2287-2292.
  Rinke, Philipp; Görls, Helmar; Liebing, Phil & Kretschmer, Robert
  
• Synthesis, Characterization, and Reactivity Studies of Bis(β‐diketiminate) Zinc(II) Complexes. Israel Journal of Chemistry, 63(7-8).
  Rinke, Philipp; Görls, Helmar & Kretschmer, Robert
  
• A gallium(i) compound with variable reactivity. Nature Synthesis, 4(1), 11-12.
  Kretschmer, Robert
  
• A singly bonded gallanediyl with redox-active and redox-inert reactivity. Nature Synthesis, 4(1), 67-74.
  Schreiner, Simon H. F.; Rüffer, Tobias & Kretschmer, Robert
  
• Accessing Homo- and Heterobimetallic Complexes with a Dianionic Pentadentate Ligand. Inorganic Chemistry, 63(42), 19665–19675.
  Schreiner, Simon H. F.; Göhler, Fabian; Almquist, C. Christopher; Rüffer, Tobias; Piers, Warren E.; Seyller, Thomas & Kretschmer, Robert
  
• Metal–metal cooperativity boosts Lewis basicity and reduction properties of the bis(gallanediyl) CyL2Ga2. Dalton Transactions, 53(11), 4922-4929.
  Helling, Christoph; Döhler, Lotta; Kysliak, Oleksandr; Görls, Helmar; Liebing, Phil; Wölper, Christoph; Kretschmer, Robert & Schulz, Stephan
  
• Utilisation of a dianionic pentadentate ligand in group 13 chemistry. Polyhedron, 250, 116824.
  Schreiner, Simon H.F.; Almquist, C. Christopher; Chang, Chia Yun; Rüffer, Tobias; Piers, Warren E. & Kretschmer, Robert