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Stereoisomerism in Tetrametallic Propeller‐Like Complexes: A Solid‐State and Solution NMR Study on a Tetragallium(III) Derivative
Author(s) -
Cornia Andrea,
Mucci Adele,
Briganti Matteo,
Bridonneau Nathalie,
Nava Andrea,
Nicolini Alessio
Publication year - 2022
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.202100873
Subject(s) - chemistry , geminal , isostructural , homonuclear molecule , crystallography , nuclear magnetic resonance spectroscopy , diastereomer , nmr spectra database , ligand (biochemistry) , paramagnetism , density functional theory , molecule , enantiomer , stereochemistry , chemical shift , diamagnetism , solid state nuclear magnetic resonance , hydroxymethyl , computational chemistry , crystal structure , nuclear magnetic resonance , spectral line , organic chemistry , biochemistry , physics , receptor , quantum mechanics , astronomy , magnetic field
Tetragallium(III) complex in [Ga 4 (L 4‐Py ) 2 (dpm) 6 ] ⋅ EtOH, with H 3 L 4‐Py =2‐(hydroxymethyl)‐2‐(pyridin‐4‐yl)propane‐1,3‐diol and Hdpm=dipivaloylmethane, was investigated as a diamagnetic analogue of tetrametallic, propeller‐like single‐molecule magnets (SMMs). The chiral molecular structure partitions the six CH 2 protons of each tripodal (L 4‐Py ) 3− ligand into two diastereotopic sets. The two signals were clearly detected by 1 H NMR spectroscopy in C 6 D 6 , proving that Λ and Δ enantiomers interconvert slowly over NMR timescale. Density functional theory calculations provided quantitative agreement with the observed values of chemical shifts and scalar coupling constants across both geminal and long‐range interaction pathways. The solid‐state structure suggests the occurrence of a lower symmetry stereoisomer (27 mol%), which was clearly identified in the NMR spectra. Since high spin Fe 3+ forms distinctly more inert complexes than Ga 3+ , comparable or greater configurational stability is expected for the isostructural Fe III 4 , Fe III 3 Cr III , and Fe III 3 V III SMMs, which are difficult to investigate by solution NMR because of the strong paramagnetism.