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

The reactions of potassium R-f-amide [R-f=tris(trifluoromethyl)phenyl] (2) with PCl3, AsCl3, and GeCl2 . dioxane yield new four-membered inorganic heterocycles [RfNPCl](2) (3), [RfNAsCl](2) (4), and [RfNGe](2) (5), respectively. On the other hand, the reaction of R-f-amide 2 with two equivalents of RfPCl2 leads to the formation of the imino-lambda(3)-phosphane RfN=PRf (6) and the diamino-lambda 3-phosphane (RfNH)(2)PRf (7). The iminophosphane 6 reacts with Ni(CO)(2)(PPh3)(2) and forms the complex [Ni(PPh3)(2)(RfN=PRf)] (9), in which the iminophosphane 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 (H-1, F-19, and P-31) 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.