The Eighteen Electron Rule is not obeyed, because the total number of electrons is 20. C₆H₅ implies a phenyl group where one of the hydrogens in the benzene ring is replaced by a covalent bond to another species. It is therefore acting as a 1e^- donor. Also the brackets in the formula .......Br(C₆H₅) mean that Br and the phenyl group is bonded separately to Pt and NOT to each other.

Pt                = 10e- Br-6-C6H5 = 6e- 2 x Pr3P      = 4e-                       20e-

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