Synthesis and reactivity of PtII complexes containing the orthometallated ligand [C6H4-2-PPh2C(H)COCH2PPh3

Abstract

The reaction of PtCl2(NCPh)2 with the ylide [Ph3PC(H)COCH2PPh3]ClO4 (1:1 molar ratio, refluxing CHCl3) affords trans-[PtCl2(NCPh){C(H)PPh3C(O)CH2PPh3}]ClO41. However, the reaction of PtCl2 (CH2Cl2, r.t.) or PtCl2(NCMe)2 (2-methoxyethanol, reflux) with the ylide [Ph3PC(H)COCH2PPh3]ClO4 (1:1 molar ratio) affords the orthometallated [Pt{C6H4-2-PPh2C(H)COCH2PPh3}(μ-Cl)]2(ClO4)2, 2, as a mixture of diastereoisomers 2a–d. Treatment of 2 with PPh3 (1:2 molar ratio) affords [PtCl{C6H4-2-PPh2C(H)COCH2PPh3}(PPh3)](ClO4), 3, as a single geometric isomer. The reaction of 2 with AgClO4 (1:2 molar ratio) in NCMe gives the solvato complex [Pt{C6H4-2-PPh2C(H)COCH2PPh3}(NCMe)2](ClO4)2, 4, while the reaction of 2 with Tl(acac) (1: 2 molar ratio) gives [Pt{C6H4-2-PPh2C(H)COCH2PPh3}(acac)](ClO4), 5. The dicationic complexes [Pt{C6H4-2-PPh2C(H)COCH2PPh3}(dppe)](ClO4)2, 6, and [Pt{C6H4-2-PPh2C(H)COCH2PPh3}(phen)](ClO4)2, 7, can be obtained by reaction of 2 with AgClO4 followed by addition of the appropiate ligand (1: 2:2 molar ratio). The reaction of 6 with NaH gives [Pt{C6H4-2-PPh2C(H)COCHPPh3}(dppe)](ClO4), 8, while the reaction of 4 with PPh3 and NaH gives [Pt{C6H4-2-PPh2C(H)COCHPPh3}(PPh3)2](ClO4), 9. Complexes 8 and 9, which contain a “free ylide” functionality, react with ClAu(tht) to give [Pt{C6H4-2-PPh2C(H)COCH(AuCl)PPh3}(dppe)](ClO4), 10, and [Pt{C6H4-2-PPh2C(H)COCH(AuCl)PPh3}(PPh3)2](ClO4), 11. In the heterobimetallic complexes 10 and 11 the ylide ligand acts as a C,C,C-terdentate ligand and, in spite of the presence of two chiral centers, only one diastereoisomer (as the mixture of two enantiomers) is observed. All complexes were characterized on the basis of their spectroscopical and analytical parameters.