The reaction of [Pt(C P)(NCMe) 2 ]ClO 4 2 [C P=ortho-(di-ortho-tolylphosphino)benzyl], with the α-stabilized phosphorus ylides Ph 3 P C(H)R (R=COMe, COPh, COOMe, CN) in a 1:1 molar ratio results in the formation of [Pt(C P){C(H)(R)PPh 3 }(NCMe)]ClO 4 (R=COMe 3, COPh 4, COOMe 5, CN 6). Complexes 3-6 appear as single isomers in which the ylide is selectively C-coordinated trans to the P atom of the C P ligand. The displacement of the remaining coordinated NCMe ligand by adding more ylide was only successfully accomplished with Ph 3 P C(H)CN, giving [Pt(C P){C(H)(CN)PPh 3 }{NC-C(H)PPh 3 }]ClO 4 7, in which one ylide is C-coordinated trans to the P atom of the C P ring and the other ylide is N-coordinated trans to the C atom, showing the ambidentate character of Ph 3 P C(H)CN as a ligand. The reaction of [Pt(C P)(μ-Cl)] 2 1 with PPh 3 (1:2 molar ratio, CH 2 Cl 2 , r.t.) results in the formation of the two expected isomers trans- and cis-[Pt(C P)Cl(PPh 3 )] (8 and 9, respectively). The trans isomer 8 is obtained as a single product by heating the mixture of isomers in toluene or, in one step, by carrying out the reaction of 1 with PPh 3 in refluxing toluene. Treatment of 8 with TlClO 4 in NCMe gives trans-[Pt(C P)(PPh 3 )(NCMe)]ClO 4 10 which can also be obtained by the reaction of 2 with PPh 3 . Complex 10 reacts with Ph 3 P C(H)R (R=COMe, COOMe, CN) in a 1:1 molar ratio resulting in the displacement of the NCMe ligand and the formation of [Pt(C P){OC(R )=C(H)PPh 3 }PPh 3 ]ClO 4 (R =Me 11, OMe 12) or [Pt(C P){NC-C(H) PPh 3 }PPh 3 ]ClO 4 13 in which the ylide ligand is selectively O- (11, 12) or N-coordinated (13). The reaction of [Pt(C P)(μ-Cl)] 2 1 with Ph 3 P C(H)R (R=COMe, COOMe, CN) in a 1:2 molar ratio results in the cleavage of the chlorine-bridge system and the formation of [Pt(C P)Cl{C(H)(R)PPh 3 }] (R=COMe 14, COOMe 15, CN 16) as single isomers in which the ylide is C-coordinated trans to the P atom of the C P ligand. Complex 14 reacts with TlClO 4 and Ph 3 P C(H)COMe (1:1:1 molar ratio) giving [Pt(C P){OC(Me) C(H)PPh 3 } 2 ]ClO 4 17. Complex 17 shows two interesting features: the isomerization of the C-linked ylide in 14 to an O-bonded one in 17 and the simultaneous presence of two O-coordinated ylides to the same metal center. The selectivity in the observed coordination modes and the preferred coordination of the ylides trans to the P atom of the C P ligand are discussed in terms of electronic and steric factors.