title: Strained, stable 2-aza-1-phosphabicyclo[n.1.0]alkane and -alkene Fe(CO)4 complexes with dynamic phosphinidene behavior.
abstract: The synthesis of highly strained bicyclic phosphirane and phosphirene iron-tetracarbonyl complexes, that is, complexes with 2-aza-1-phosphabicyclo[n.1.0]alkanes and -alkenes (n = 3-5), is explored by using intramolecular cycloaddition of an in situ generated electrophilic phosphinidene complex, [R(iPr)NP=Fe(CO)(4)], to its C=C- and C[triple chemical bond]C-containing R substituent. Saturated bicyclic complexes 7 a-c with n = 4-2 are remarkably stable, as illustrated by the X-ray crystal structure for 7 b (n=3), yet all readily undergo retroaddition to react with phenylacetylene. Shuttling of the phosphinidene iron complex between two equivalent C=C groups is demonstrated for a 1-butene-substituted 2-aza-1-phosphabicyclo[3.1.0]hexane by selective (1)H NMR magnetization transfer from the phosphirane protons to the olefinic protons. Even the more strained unsaturated bicycles 17 a,b (n = 4,3) are surprisingly stable as illustrated by the X-ray crystal structure for 17 a (n = 4), but the smaller phosphabicyclo[3.1.0]hex-5-ene (17 c, n = 2) dimerizes to tricyclic 19 with a unique ten-membered heterocyclic ring; an X-ray crystal structure is reported. Like their saturated analogues also the bicyclic phosphirenes readily undergo retroaddition as shown by the reaction of their phosphinidene iron moiety with phenylacetylene.
authors.affiliation: Vrije Universiteit, Faculty of Sciences, Department of Chemistry, Amsterdam, The Netherlands.
authors.forename: Mark L G
authors.initials: ML
authors.lastname: Borst
authors.forename: Niels
authors.initials: N
authors.lastname: van der Riet
authors.forename: Renske H
authors.initials: RH
authors.lastname: Lemmens
authors.forename: Franciscus J J
authors.initials: FJ
authors.lastname: de Kanter
authors.forename: Marius
authors.initials: M
authors.lastname: Schakel
authors.forename: Andreas W
authors.initials: AW
authors.lastname: Ehlers
authors.forename: Allison M
authors.initials: AM
authors.lastname: Mills
authors.forename: Martin
authors.initials: M
authors.lastname: Lutz
authors.forename: Anthony L
authors.initials: AL
authors.lastname: Spek
authors.forename: Koop
authors.initials: K
authors.lastname: Lammertsma
mesh_terms: D000475:Alkenes / Q000138:chemical synthesis* / Q000737:chemistry; D001372:Aza Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D018360:Crystallography, X-Ray; D058085:Iron Compounds / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods / Q000592:standards; D008958:Models, Molecular; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D010720:Phosphines / Q000737:chemistry*; D012015:Reference Standards
chemical_list: D000475:Alkenes; D001372:Aza Compounds; D058085:Iron Compounds; D009942:Organometallic Compounds; D010720:Phosphines