Reactions of two dinaphthyl phosphines with [Cp*IrCl] have been carried out. In the case of di(α-naphthyl)phenylphosphine (), a simple P-coordinated neutral adduct is obtained. However, -butyldi(α-naphthyl)phenylphosphine () is cyclometalated to form [Cp*IrCl(P^C)] (). Complexes and undergo further cyclometalation to give the corresponding double cyclometalated complexes [Cp*Ir(C^P^C)] (,) upon heating. In the presence of sodium acetate, reactions of , with [Cp*IrCl] directly afford the final double cyclometalated complexes (,). In the absence of acetate, [Cp*RhCl] shows no reaction with ,, whereas with acetate the reactions form the corresponding single cyclometalated complexes [Cp*RhCl(P^C)] (,), which react with BuOK to form the corresponding rhodium hydride complexes (,). Treatment of with CuCl or I leads to opening of two Ir-C σ bonds to yield the corresponding P-coordinated iridium dihalide ( or ) by means of an intramolecular C-C coupling reaction. A new chiral phosphine () is formed by the ligand-exchange reaction of with PMe. Reactions of the single cycloiridated complex with terminal aromatic alkynes result in the corresponding five- and six-membered doubly cycloiridated complex and/or η-alkene coordinated complexes ; the latter discloses that the electronic effect of terminal alkynes affects the regioselectivity. While the single cyclorhodated complex reacts with terminal aromatic alkynes to form the corresponding six-membered cyclometalated complexes by vinylidene rearrangement/1,1-insertion. Plausible pathways for formation of insertion products were proposed. Molecular structures of twelve new complexes were determined by X-ray diffraction.