Deprotonation of a hydrophosphorane and synthesis of the Ni(II) metallophosphorane [NiCl{P(OC6H4N(CH3))2}(P(CH3)3)2]

• We deprotonate a hydrophosphorane using LiTMP.
• The lithium phosphoranide is isolated in high yield and features a P(III) atom.
• However on coordination to Ni, the species returns to P(V).
• The Ni(II) structure features tetrahedral distortion and a Ni-O close approach.
• We provide further evidence M→P pi-donation in a metalated phosphorane structure.

The hydrophosphorane [HP(OC6H4N(CH3))2] has been deprotonated using lithium tetramethylpiperidide to produce Li[P(OC6H4N(CH3))2] (1). Compound 1 reacts further with NiCl2(PMe3)2 to form the Ni(II) phosphoranide complex [NiCl{P(OC6H4N(CH3))2}(P(CH3)3)2] (2). The crystal structures of both 1 and 2 were determined. The structure of 1 is dimeric with bridging lithium cations and also features one THF solvent molecule coordinated to each lithium cation; the geometry about the lithium atom is tetrahedral. The structure of 2 displays tetrahedral distortion from an idealized square-planar geometry. Both 1 and 2 characterized by 1H and 31P NMR, with 13C NMR for 2 also. DFT calculations (B3LYP/6-311++G(2df,2p)) were also done on 2; both the NMR and DFT studies indicate π-donation from the metal to the pentacoordinate phosphorus.

Upon deprotonation, the hydrophosphorane HP(OC6H4NMe)2 yields a P(III) species, but further metathesis with NiCl2(PMe3)2 produces the P(V) phosphoranide trans-[NiCl{P(OC6H4NMe)2}(PMe3)2].Figure optionsDownload as PowerPoint slide