Beginning with inexpensive and commercially available starting materials, a rational synthesis for the new phosphaalkyne Ph3C-C⋮ P (1) is presented. Coordination of 1 to group 8 transition metal centers furnishes the η1-complexes [MH (dppe) 2 (Ph3CC⋮ P)] OTf, where M= Fe (3) or Ru (4)(dppe= bis-1, 2-diphenylphosphinoethane). Treatment of 3 or 4 with a strong acid cyclizes the coordinated phosphaalkyne and is the first example of an ...