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Li S, Schröder M, Prudlik A, Shi X, Spannenberg A, Rabeah J, Francke R, Corzilius B, Reiß F, Beweries T. A General Concept for the Electronic and Steric Modification of 1-Metallacyclobuta-2,3-dienes: A Case Study of Group 4 Metallocene Complexes. Chemistry 2024; 30:e202400708. [PMID: 38529695 DOI: 10.1002/chem.202400708] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2024] [Revised: 03/22/2024] [Accepted: 03/25/2024] [Indexed: 03/27/2024]
Abstract
The synthesis of group 4 metal 1-metallacyclobuta-2,3-dienes as organometallic analogues of elusive 1,2-cyclobutadiene has so far been limited to SiMe3 substituted examples. We present the synthesis of two Ph substituted dilithiated ligand precursors for the preparation of four new 1-metallacyclobuta-2,3-dienes [rac-(ebthi)M] (M=Ti, Zr; ebthi=1,2-ethylene-1,10-bis(η5-tetrahydroindenyl)). The organolithium compounds [Li2(RC3Ph)] (1 b: R=Ph, 1 c: R=SiMe3) as well as the metallacycles of the general formula [rac-(ebthi)M(R1C3R2)] (2 b: M=Ti, R1=R2=Ph, 2 c: M=Ti, R1=Ph, R2=SiMe3; 3 b: M=Zr, R1=R2=Ph; 3 c: M=Zr, R1=Ph, R2=SiMe3) were fully characterised. Single crystal X-ray diffraction and quantum chemical bond analysis of the Ti and Zr complexes reveal ligand influence on the biradicaloid character of the titanocene complexes. X-band EPR spectroscopy of structurally similar Ti complexes [rac-(ebthi)Ti(Me3SiC3SiMe3)] (2 a), 2 b, and 2 c was carried out to evaluate the accessibility of an EPR active triplet state. Cyclic voltammetry shows that introduction of Ph groups renders the complexes easier to reduce. 13C CPMAS NMR analysis provides insights into the cause of the low field shift of the resonances of metal-bonded carbon atoms and provides evidence of the absence of the β-C-Ti interaction.
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Affiliation(s)
- Sihan Li
- Leibniz Institute for Catalysis, Albert-Einstein-Str. 29a, 18059, Rostock, Germany
| | - Mirjam Schröder
- Leibniz Institute for Catalysis, Albert-Einstein-Str. 29a, 18059, Rostock, Germany
- University of Rostock, Institute of Chemistry, 18059, Rostock, Germany
- University of Rostock, Department LL&M, 18059, Rostock, Germany
| | - Adrian Prudlik
- Leibniz Institute for Catalysis, Albert-Einstein-Str. 29a, 18059, Rostock, Germany
- University of Rostock, Institute of Chemistry, 18059, Rostock, Germany
| | - Xinzhe Shi
- Leibniz Institute for Catalysis, Albert-Einstein-Str. 29a, 18059, Rostock, Germany
- School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin, 150001, P. R. China
| | - Anke Spannenberg
- Leibniz Institute for Catalysis, Albert-Einstein-Str. 29a, 18059, Rostock, Germany
| | - Jabor Rabeah
- Leibniz Institute for Catalysis, Albert-Einstein-Str. 29a, 18059, Rostock, Germany
| | - Robert Francke
- Leibniz Institute for Catalysis, Albert-Einstein-Str. 29a, 18059, Rostock, Germany
| | - Björn Corzilius
- Leibniz Institute for Catalysis, Albert-Einstein-Str. 29a, 18059, Rostock, Germany
- University of Rostock, Institute of Chemistry, 18059, Rostock, Germany
- University of Rostock, Department LL&M, 18059, Rostock, Germany
| | - Fabian Reiß
- Leibniz Institute for Catalysis, Albert-Einstein-Str. 29a, 18059, Rostock, Germany
| | - Torsten Beweries
- Leibniz Institute for Catalysis, Albert-Einstein-Str. 29a, 18059, Rostock, Germany
- University of Rostock, Department LL&M, 18059, Rostock, Germany
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