The electronic structure of a β-diketiminate manganese hydride dimer

Changjin Oh, Joëlle Siewe, Thao T. Nguyen, Airi Kawamura, Marco Flores, Thomas L. Groy, John S. Anderson, Ryan J. Trovitch, Mu Hyun Baik

Research output: Contribution to journalArticlepeer-review

Abstract

The electronic structure of a dimeric manganese hydride catalyst supported by β-diketiminate ligands, [(2,6-iPr2PhBDI)Mn(μ-H)]2, was investigated with density functional theory. A triple bond between the manganese centres was anticipated from simple electron-counting rules; however, calculations revealed Mn-Mn Mayer bond orders of 0.21 and 0.27 for the ferromagnetically-coupled and antiferromagnetically-coupled extremes, respectively. In accordance with experimentally determined Heisenberg exchange coupling constants of -15 ± 0.1 cm-1 (SQUID) and -10.2 ± 0.7 cm-1 (EPR), the calculated J0 value of -10.9 cm-1 confirmed that the ground state involves antiferromagnetic coupling between high spin Mn(ii)-d5 centres. The effect of steric bulk on the bond order was examined via a model study with the least sterically-demanding version of the β-diketiminate ligand and was found to be negligible. Mixing between metal- and β-diketiminate-based orbitals was found to be responsible for the absence of a metal-metal multiple bond. The bridging hydrides give rise to a relatively close positioning of the metal centres, while bridging atoms possessing 2p orbitals result in longer Mn-Mn distances and more stable dimers. The synthesis and characterization of the bridging hydroxide variant, [(2,6-iPr2PhBDI)Mn(μ-OH)]2, provides experimental support for these assessments. This journal is

Original languageEnglish
Pages (from-to)14463-14474
Number of pages12
JournalDalton Transactions
Volume49
Issue number41
DOIs
Publication statusPublished - Nov 7 2020

ASJC Scopus subject areas

  • Inorganic Chemistry

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