Strained, stable 2-aza-1-phosphabicyclo[n.1.0]alkane and -alkene Fe(CO)4 complexes with dynamic phosphinidene behavior.
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.
Borst
Mark L G
ML
Vrije Universiteit, Faculty of Sciences, Department of Chemistry, Amsterdam, The Netherlands.
van der Riet
Niels
N
Lemmens
Renske H
RH
de Kanter
Franciscus J J
FJ
Schakel
Marius
M
Ehlers
Andreas W
AW
Mills
Allison M
AM
Lutz
Martin
M
Spek
Anthony L
AL
Lammertsma
Koop
K
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
D000475:Alkenes; D001372:Aza Compounds; D058085:Iron Compounds; D009942:Organometallic Compounds; D010720:Phosphines