Phosphinimine complexes of technetium(VII): X-ray crystal structure of [Ph3P = NH2+][TcO4-](1)

An X-ray diffraction study and the solution chemistry is reported for the v ery stable ion pair [Ph3P = NH2+[TcO4-]. This compound crystallizes in the orthorhombic system, in space group P2(1)2(1)2(1), With cell dimensions of a = 11.1454(6), b = 11.449(2), and c = 14.570(2)Angstrom, and refining to R = 0.023 and R-w = 0.031. Strong hydrogen bonds are formed between the imin ium protons and the pertechnetate oxygens (1.89(6) and 2.23(6) Angstrom) in the solid state, and similar hydrogen bonding apparently occurs in aqueous solution to stabilize the phosphiniminium cation to hydrolysis.