Selektive Additionsreaktionen an bifunktionalen neutralen Phosphenium-Ion-Komplexen / Selective Addition Reactions of Bifunctional Neutral Phosphenium Ion Complexes

The reaction of bifunctional neutral phosphenium ion complexes, containing a carbon-carbon triple bond next to a phosphorus-molybdenum multiple bond, with carbenes and to carbene isolobal organometallic fragments is discussed.

So, the reaction of (R)(PhC=C)P=MoCp′(CO), (R = 2,4,6-′Bu₃C₆H₂O; Cp′ = η⁵-C₅H₅: la; Cp′ = η⁵-C₅Me₅: 1b) with CH₂,Ν₂ (2) yields the three membered heterocyclic compound (3). 3 reacts with Co₂(CO)₈ to afford complex (5) in which the phenylethynyl building block is η²-side-on coordinated to a Co₂(CO)₆ fragment. Similar to the reaction of 1 with 2, 1 forms with Fe₂(CO)₉ (6), compound (7). In 7 the PMo double bond is coordinated in a η² fashion to the 16-electron organometallic fragment Fe(CO)₄. Using an excess of 6 and a higher temperature, the phosphorus-alkynyl-carbon σ-bond is cleaved, and cluster MoCp*Fe₃(CO)₈η₃-PR)(C≡CPh) (8) is formed.

The reaction of 1 with Cr(CO)₅(THF) yields 10, a complex, in which the PhC≡C ligand is η²-coordinated to Cp′(CO)₂Mo, and the Cr(CO)₅ group forms a dative bond with the phosphorus atom.

All new compounds have been characterized by analytical as well as by spectroscopic data (IR, ¹H, ³¹P, ¹³C NMR, MS), compound 10 by an X-ray analysis.