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.

本研究报道了氧合铼配合物OReCl₂(BDI)（化合物1，其中BDI为N,N'-双(2,6-二异丙基苯基)-β-二酮亚胺配体）的两条合成路线，并对该配合物的性质与反应活性进行了系统讨论。本研究分离并表征了化合物1与4-二甲基氨基吡啶（DMAP，对应加合物为1-DMAP）、2,6-二甲基苯基异氰（XylNC，对应加合物为1-XylNC）以及三乙基膦（PEt₃，对应加合物为1-PEt₃）形成的多种加合物。此外，为探究BDI骨架在高氧化态铼配合物中的辅助配体局限性，本研究开展了化合物1与氧原子转移（Oxygen Atom Transfer, OAT）反应的相关探究。研究发现，在热解条件下，通过核磁共振波谱可观测到化合物1与PEt₃之间发生氧原子转移反应，证实新物种(ArN)ReCl₂(MAD)(PEt₃)（化合物2，其中Ar为2,6-二异丙基苯基，MAD为4-((2,6-二异丙基苯基)亚氨基)戊-2-烯基配体）成功生成。本研究提出了一条由BDI配体向铼中心转移氮宾以生成化合物2的反应机理。研究人员解析了配合物1、1-PEt₃、1-DMAP以及2的X射线晶体结构，并对其进行了详细阐释。