Formation and cleavage of platinacycles containing a fluorinated imine. Crystal structure of [PtMe(3,4,5-C 6HF 3CHNCH 2C 6H 5)PPh 3

Abstract

The reaction of [Pt 2Me 4(μ-SMe 2) 2] with the ligand 3,4,5-C 6H 2F 3CHNCH 2C 6H 5 ( L) yielded the cyclometallated platinum(II) compound [PtMe(3,4,5-C 6HF 3CHNCH 2C 6H 5)SMe 2] ( 1), in which the imine acts as a [C,N]-bidentate ligand. Compounds [PtMe(3,4,5-C 6HF 3CHNCH 2C 6H 5)DMSO] ( 2) (DMSO=dimethyl sulfoxide) and [PtMe(3,4,5-C 6HF 3CHNCH 2C 6H 5)PPh 3] ( 3) were obtained from a displacement reaction of SMe 2 for DMSO or PPh 3, respectively. Oxidative addition of methyl iodide to compounds 1– 3 produced, respectively, [PtMe 2I(3,4,5-C 6HF 3CHNCH 2C 6H 5)SMe 2] ( 4a/ 4b) as two isomers, [{PtMe 2I(3,4,5-C 6HF 3CHNCH 2C 6H 5)} 2] ( 5) and [PtMe 2I(3,4,5-C 6HF 3CHNCH 2C 6H 5)PPh 3] ( 6). Platinum(II) metallacycles can be cleaved upon reaction with an excess of PPh 3 or with the diphosphine dppe to yield, respectively, compounds [PtMe(3,4,5-C 6HF 3CHNCH 2C 6H 5)(PPh 3) 2] ( 7) and [PtMe(3,4,5-C 6HF 3CHNCH 2C 6H 5)dppe] ( 8) in which the imine acts as a monodentate [C] ligand. Analogous compounds could not be obtained for platinum(IV) since in this case neither PPh 3 nor dppe can cleave the metallacycle. The reaction of 4a/ 4b with dppe produced [{PtMe 2I(3,4,5-C 6HF 3CHNCH 2C 6H 5)} 2dppe] ( 11), a binuclear compound in which the diphosphine bridges two platinum(IV) moieties with the imine acting as a [C,N]-bidentate ligand. All compounds were characterised by analytical and spectroscopic techniques and compound 3 was also characterised crystallographically.