Metal‐Promoted Cyclotrimerization of a λ3‐Phosphaalkyne: Formation of a Molybdenum‐Coordinated 1,3,5‐Triphosphabenzene

The excellent synthetic potential of the phosphaalkynes, analogous to that of the alkynes, can be demonstrated once again with the title reaction. Reaction of [η6-C7H7Mo(CO)3] with tBuCP in THF yields the 1H- and 31P-NMR and IR spectroscopically characterized complex 1 in the form of orange microcrystals. The 31P chemical shift of the coordinated η6-triphosphabenzene ligand in 1 is δ = 25.2.