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Stereoisomeric Control in [RuCl 2 (PTA) 2 (2L)] Complexes (2L=2py or bpy): From Theoretical Calculations to a 2+2 Metallacycle of Pyridylporphyrins
Author(s) -
Vidal Alessio,
Battistin Federica,
Milani Barbara,
Balducci Gabriele,
Alessio Enzo
Publication year - 2021
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.202000996
Subject(s) - chemistry , pyridine , steric effects , metallacycle , reactivity (psychology) , stereochemistry , molecule , bipyridine , cis–trans isomerism , aqueous solution , medicinal chemistry , crystallography , crystal structure , x ray crystallography , organic chemistry , medicine , physics , alternative medicine , pathology , diffraction , optics
Treatment of the Ru(II) precursor cis,cis,trans ‐[RuCl 2 (dmso‐S) 2 (PTA) 2 ] ( 1 , PTA=1,3,5‐triaza‐7‐phosphaadamantane) with 2,2′‐bipyridine (bpy) in refluxing ethanol selectively affords cis,cis ‐[Ru(bpy)Cl 2 (PTA) 2 ] ( 2 ), whereas with pyridine (py), under the same conditions, it gives trans,cis,cis ‐[RuCl 2 (PTA) 2 (py) 2 ] ( 6 ). The slightly less stable stereoisomer of 2 , cis,trans ‐[Ru(bpy)Cl 2 (PTA) 2 ] ( 3 ), is obtained selectively through a different synthetic route. Isomers 2 and 3 are thermally stable, but cleanly equilibrate upon irradiation of an aqueous solution of either one with blue light. Intrigued by the stereoisomeric outcome in the preparations of this homogeneous set of complexes, we also investigated 2 , 3 , and 6 (and the mono‐pyridine complex trans,mer ‐[RuCl 2 (py)(PTA) 3 ] ( 7 )) through a topological analysis of the electron density map using the quantum theory of atoms in molecules (QTAIM). The wealth of acquired experimental and calculated data allow us to discuss the stereochemical preferences of the [RuCl 2 (PTA) 2 (2 L)] complexes (2 L=bpy or 2py) in terms of electronic and steric contributions. The results of this speculative study on model complexes are transferable to similar systems. As an example, our findings from the reactivity of 1 towards pyridine allowed us to prepare the 2+2 pyridylporphyrin metallacycle trans,cis,cis ‐[RuCl 2 (PTA) 2 (4′‐ cis DPyP)] 2 ( 10 , 4′‐ cis DPyP=5,10‐(4′‐pyridyl)‐15,20‐(phenyl)‐porphyrin), whose X‐ray molecular structure is also reported.