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Ligand‐ and Metal‐Based Reactivity of a Neutral Ruthenium Diolefin Diazadiene Complex: The Innocent, the Guilty and the Suspicious
Author(s) -
Sinha Vivek,
Pribanic Bruno,
de Bruin Bas,
Trincado Monica,
Grützmacher Hansjörg
Publication year - 2018
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201705957
Subject(s) - chemistry , singlet state , carbene , open shell , ligand (biochemistry) , reactivity (psychology) , ruthenium , moiety , bond cleavage , photochemistry , computational chemistry , stereochemistry , crystallography , excited state , physics , catalysis , atomic physics , organic chemistry , medicine , biochemistry , receptor , alternative medicine , pathology
Coordination of the diazadiene diolefin ligand (trop 2 dad) to ruthenium leads to various complexes of composition [Ru(trop 2 dad)(L)]. DFT studies indicate that the closed‐shell singlet (CSS), open‐shell singlet (OSS), and triplet electronic structures of this species are close in energy, with the OSS spin configuration being the lowest in energy for all tested functionals. Singlet‐state CASSCF calculations revealed a significant multireference character for these complexes. The closed‐shell singlet wavefunction dominates, but these complexes have a significant (≈8–16 %) open‐shell singlet [d 7 ‐Ru I (L)(trop 2 dad .− )] contribution mixed into the ground state. In agreement with their ambivalent electronic structure, these complexes reveal both metal‐ and ligand‐centered reactivity. Most notable are the reactions with AdN 3 , diazomethane, and a phosphaalkyne leading to scission of the C−C bond of the diazadiene (dad) moiety of the trop 2 dad ligand, resulting in net (formal) nitrene, carbene, or P≡C insertion in the dad C−C bond, respectively. Supporting DFT studies revealed that several of the ligand‐based reactions proceed via low‐barrier radical‐type pathways, involving the dad .− ligand radical character of the OSS or triplet species.