The role of the 2,4,6-tris(trifluoromethyl)phenylamino group in stabilizing new phosphorus-, arsenic-, and germanium-containing main-group compounds and transition-metal derivatives

Abstract

The reactions of potassium R_f-amide [R_f = tris(trifluoromethyl)phenyl](2) with PCl₃, AsC1₃, and GeC1₂ · dioxane yield new four-membered inorganic heterocycles [R_fNPCl]₂(3), [R_fNAsC1]₂(4), and [R_fNGe]₂(5), respectively. On the other hand, the reaction of R_f-amide 2 with two equivalents of R_fPCl₂ leads to the formation of the imino-γ³-phosphane R_fN=PR_f(6) and the diamino-3-phosphane (R_fNH)₂PR_f(7). The iminophosphane 6 reacts with Ni(CO)₂(PPh₃)₂ and forms the complex [Ni(PPh₃)₂(R_fN=PR_f)] (9), in which the imino- phosphane coordinates to the metal through the phosphorus lone pair. Treatment of lithium amide 2 with transition metal chlorides ZnCl₂ and FeCl₂ yields the imido/amido spirocyclic metal derivatives 9 and 10, respectively. Compounds 3-10 have been extensively characterized by their analytical and mass, IR, and NMR (¹H, ¹⁹F, and ³¹P) spectroscopy. Further, the molecular structures of all the compounds have been unambiguously determined by single-crystal X-ray diffraction studies. The diazadigermetidine 5 crystallizes in a fluorescent-yellow orthorhombic and a yellow monoclinic crystal modification. The results obtained reveal the role of R_f, group in stabilizing new multiple bonded systems and inorganic heterocycles. A skeletal rearrangment of the R_f ligand is observed in the reactions leading to compounds 9 and 10. Moreover, the preparation of compounds 9 and 10 indicates the limitation of the use of this ligand in the preparation of new metal-amide systems, especially where the metal atoms have a strong tendency for the formation of strong M-F bonds.