Oxygen Atom Transfer and Intramolecular Nitrene Transfer in a Rhenium β‑Diketiminate Complex

We present two routes to the oxo
rhenium complex OReCl2(BDI) (1) (BDI = N,N′-bis­(2,6-diisopropylphenyl)-β-diketiminate)
and discuss the properties and reactivity of this material. Several
adducts of 1 with DMAP (1-DMAP; DMAP = 4-dimethylaminopyridine),
isonitriles (1-XylNC; XylNC = 2,6-dimethylphenyl isocyanide),
and phosphines (1-PEt3; PEt3 = triethylphosphine) were isolated and characterized. Additionally,
to probe the ancillary limitations of the BDI framework in high-valent
rhenium complexes, oxygen atom transfer (OAT) reactivity with 1 was pursued. It was found that under thermolysis conditions
OAT between 1 and PEt3 was observed by NMR
spectroscopy, which indicated the formation of a new species, (ArN)­ReCl2­(MAD)­(PEt3) (2; Ar = 2,6-diisopropylphenyl,
MAD = 4-((2,6-diisopropylphenyl)­imino)­pent-2-enide). A mechanism for
the generation of 2 involving nitrene transfer to rhenium
from the BDI ligand is proposed. X-ray crystal structures of complexes 1, 1-PEt3, 1-DMAP, and 2 were determined and are discussed in detail.