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The Missing Link: Manganese Complexes with Sterically Demanding Pyrrolyl Ligands
Author(s) -
Kreye Markus,
Freytag Matthias,
Daniliuc Constantin G.,
Jones Peter G.,
Walter Marc D.
Publication year - 2015
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/zaac.201500555
Subject(s) - chemistry , manganese , ligand (biochemistry) , steric effects , adduct , crystallography , stereochemistry , density functional theory , sublimation (psychology) , computational chemistry , psychology , biochemistry , receptor , organic chemistry , psychotherapist
Reaction of NaPyr t Bu 2 [Pyr t Bu 2 = 2, 5‐(Me 3 C) 2 C 4 H 2 N] and KPyr t Bu 2 Me 2 [Pyr t Bu 2 Me 2 = 2, 5‐(Me 3 C) 2 ‐3, 4‐Me 2 C 4 N] with MnI 2 (thf) 3 resulted in the isolation of the first bis(pyrrolyl)manganese(II) complexes. However, different coordination modes are realized depending on the identity of the Pyr‐ligand. For example, the Mn II atom is κ N coordinate in [(κ N ‐Pyr t Bu 2 ) 2 Mn] ( 1‐Mn ), whereas several different species were isolated with the more bulky Pyr t Bu 2 Me 2 ligand. Depending on the reaction conditions the κ N ‐coordinate complex [(κ N ‐Pyr t Bu 2 Me 2 ) 2 Mn] ( 2‐Mn′ ) is initially formed, but converts on sublimation to the η 3 coordinate isomer [(η 3 ‐Pyr t Bu 2 Me 2 ) 2 Mn] ( 2‐Mn′ ). In some cases we could also identify a THF adduct of 2‐Mn to give [(κ N ‐Pyr t Bu 2 Me 2 )(η 2 ‐Pyr t Bu 2 Me 2 )Mn(thf)] [ 2‐Mn(thf) ], in which one Pyr t Bu 2 Me 2 ligand binds in a κ N coordination mode, while the other is best described as η 2 ‐Pyr t Bu 2 Me 2 . These complexes were characterized by elemental analyses and X‐ray diffraction studies. Density functional theory (DFT) computations confirm that the potential energy surface between the different hapticities is rather flat for these Mn II high‐spin species ( S = 5/2).