Synthesis, Solid-State Crystal Structure, and Reactivity of a Monomeric Copper(I) Anilido Complex

Synthesis and isolation of the Cu(I) amido complex (dtbpe)Cu(NHPh) (dtbpe = 1,2-bis(di-tert-butylphosphino)ethane) is accomplished upon reaction of [(dtbpe)Cu(μ-Cl)]₂ with LiNHPh. The anilido complex has been fully characterized by IR spectroscopy and multinuclear NMR spectroscopy as well as by single-crystal X-ray diffraction study. Salient features of the solid-state structure include an amido orientation that allows π-interaction of the nitrogen-based lone pair with both the empty copper p-orbital and the π*-system of the phenyl substituent. A solid-state X-ray diffraction study of [(dtbpe)Cu(NH₂Ph)][BF₄] has allowed a direct comparison of the structural features upon conversion of the amine ligand to an amido. The reactivity of the amido ligand of (dtbpe)Cu(NHPh) is consistent with nucleophilic character. For example, the formation of Ph₃CNHPh is observed upon treatment with [Ph₃C][BF₄], and reaction at room temperature with EtX (X = Br or I) yields N-ethylaniline. The reactivity of (dtbpe)Cu(NHPh) is compared to that of the octahedral and d⁶ complex TpRu(PMe₃)₂(NHPh) (Tp = hydridotris(pyrazolyl)borate).