title: Synthesis of the 2,4,5-tri-tert-butyl-1,3-diphospholide anion by phosphinidene elimination from 2,4,6-tri-tert-butyl-1,3,5-triphosphabenzene on treatment with the amide Li[NPh(SiMe3)].
abstract: Treatment of the lithium amide Li[NPh(SiMe3)] with 2,4,6-tri-tert-butyl-1,3,5-triphosphabenzene, P(3)C(3)tBu(3), in a 1:2 ratio afforded equimolar amounts of the lithium salt of the five-membered 2,4,5-tri-tert-butyl-1,3-diphospholide anion, LiP(2)C(3)tBu(3) (isolated as its N,N,N',N'-tetramethylethylenediamine (TMEDA) adduct), and the tricyclic compound 6-[phenyl(trimethylsilyl)amino]-3,5,7-tri-tert-butyl-1,2,4,6-tetraphosphatricyclo[3.2.0.0(2,7)]hept-3-ene. Both compounds have been structurally characterised by single-crystal X-ray diffraction studies. The mechanism of this remarkable reaction has been elucidated by theoretical methods at the B3LYP/6-311+G** level of theory. The reaction involves a hitherto unobserved aminophosphinidene, which was formed by abstraction of a phosphorus atom from triphosphabenzene. The intermediate aminophosphinidene, which is further stabilised by the solvent THF, shows, in agreement with previous theoretical predictions, enhanced stability and reacts then with a second molecule of triphosphabenzene.
authors.affiliation: Chemistry Department, School of Life Sciences, University of Sussex, Brighton, BN1 9QJ, Sussex, UK.
authors.forename: Scott B
authors.initials: SB
authors.lastname: Clendenning
authors.forename: Peter B
authors.initials: PB
authors.lastname: Hitchcock
authors.forename: Michael F
authors.initials: MF
authors.lastname: Lappert
authors.forename: Philippe G
authors.initials: PG
authors.lastname: Merle
authors.forename: John F
authors.initials: JF
authors.lastname: Nixon
authors.forename: László
authors.initials: L
authors.lastname: Nyulászi
mesh_terms: D000577:Amides / Q000737:chemistry; D000838:Anions; D018360:Crystallography, X-Ray; D008094:Lithium / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008968:Molecular Conformation; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000737:chemistry*; D009943:Organophosphorus Compounds / Q000138:chemical synthesis* / Q000737:chemistry*
chemical_list: C523339:2,4,6-tri-tert-butyl-1,3,5-triphosphabenzene; D000577:Amides; D000838:Anions; D009942:Organometallic Compounds; D009943:Organophosphorus Compounds; D008094:Lithium