The reaction of (NPF2)3 with 2.0 equiv of Li[BEt3H] in THF at 25 °C yields a triethylborane-stabilized fluorophosphazene anion [N3P3FsBEt3]−. This species possesses a nucleophilic P(V) center that reacts readily with organic halides such as Mel or PhCH2Br, with CF3CH2OH as a proton source, or with organometallic halides such as CpFe(CO)2I to produce N3P3F6Me, N3P3F5CH2Ph, N3P3F5H, or N3P3F5Fe(CO)2Cp, respectively. The remaining fluorine atoms in these products were replaced by trifluoroethoxy groups to facilitate characterization. Reaction of (NPF2)3 with 3 equiv of Li[BEt3H] in THF or reaction of the fluorophosphazene anion, [N3P3F6BEt3]−, with 1 equiv of Li[BEt3H] generated a hy dridophosphazene anion [N3P3F4HBEt3]−. Similarly, reaction of the transannular ferrocenyl species N3P3F4(η-C5H4)Fe with 3 equiv of Li[BEt3H] in THF produced the hydridophosphazene anion [N3P3F2H(BEt3)(η-C5H4)2Fe]− in high yield. The electronic structures of the hydridophosphazene anions [N3P3F4HBEt3]− or [N3P3F2H(BEt3)(η-C6H4)2Fe]− appear to differ significantly from that of the fluoro phosphazene anion [N3P3F5BEt3]−. Spectroscopic and reactivity studies suggest that the phosporus atom in the hydrido species exists in the +3 oxidation state, with the negative charge residing mainly on skeletal nitrogen. This situation is supported by the X-ray diffraction study of the hydridophosphazene anion [N3P3F2H(BEt3)(η-C5H4)2Fe]−[Li(THF)3]+, in which the lithium cation is coordinated to a skeletal nitrogen atom and is also surrounded by three THF molecules. Crystals of this compound are monoclinic, with a P21/c space group and with α = 11.363 (3) Å, b = 27.701 (9) Å, c = 11.667 (5) Å, β = 115.42 (4)°, V = 3316.8 Å3, and Z = 4.
All Science Journal Classification (ASJC) codes
- Physical and Theoretical Chemistry
- Organic Chemistry
- Inorganic Chemistry