Synthesis of the Sterically Shielded Rhodium(I) Arene Complex by Cycloaddition of the Phosphorous‐Substituted Alkyne.

Reaction of two molecules of o‐diphenylphosphino‐tolane with RhCl(PPh3)3 produces the metallacycle complex with C4Rh(P3)Cl core. Further addition of tolane leads to 2+2+2‐cycloaddition and gives the cationic complex [Rh(Ph2P−C6H4−C6Ph4−C6H4−PPh2)]Cl, in which the metal is coordinated to C6Ph4 aromatic ring as well to two chelating PPh2 groups. The resulting bulky terphenyl‐diphosphine ligand with phosphorous atoms locked in cis‐position can be decoordinated from rhodium by a strong and non‐hindered ligand tBuNC. Peculiar structures of all the compounds were studied by the X‐ray diffraction. [ABSTRACT FROM AUTHOR]