Ligand- and Metal-Based Reactivity of a Neutral Ruthenium Diolefin Diazadiene Complex: The Innocent, the Guilty and the Suspicious.

ABSTRACT: Coordination of the diazadiene diolefin ligand (trop₂ dad) to ruthenium leads to various complexes of composition [Ru(trop₂ 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 [d⁷ -Ru^I (L)(trop₂ 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 AdN₃ , diazomethane, and a phosphaalkyne leading to scission of the C-C bond of the diazadiene (dad) moiety of the trop₂ 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.

SUBMITTER: Sinha V 

PROVIDER: S-EPMC5947567 | biostudies-literature | 2018 Apr

REPOSITORIES: biostudies-literature