Design of alkyl- and haloalkyl complexes of dimethylplatinum(IV) via oxidative addition: Reactivity, characterization and crystal structures

The oxidative addition of benzyl bromide to organoplatinum(II) complexes [PtMe2(NN)] {NN=5,5′-Me2bpy (5,5′-dimethyl-2,2′-bipyridine; phen (1,10-phenanthroline)} has been investigated. The reaction of [PtMe2(NN)] with dihaloalkanes CH2Cl2 and Br(CH2)4Br affords a mixture of cis and trans-[PtMe2(CH2Cl)Cl(NN)] and trans-[PtMe2{(CH2)4Br}Br(NN)], respectively, formed by the oxidative addition of one of the carbon-halide bonds. The crystal structures of [PtMe2(CH2Cl)Cl(4,4′-Me2bpy)] and [PtMe2{(CH2)4Br}Br(4,4′-Me2bpy)] reveal that the halomethylene chain of CH2Cl and (CH2)4Br units are twisted respect to the 4,4′-Me2bpy ligand with a syn arrangement. [Display omitted] •New benzyl complexes of dimethylplatinum(IV) were synthesized.•Oxidative addition of [PtMe2(NN)] with CH2Cl2 and Br(CH2)4Br were investigated.•Two haloalkyl complexes of Pt(IV) were characterized by X-ray structural analysis.•The CH2Cl and (CH2)4Br units are twisted respect to the 4,4′-Me2bpy ligand.•First example of crystal structure of Pt(IV) complex having long chain of methylene. Dimethylplatinum(II) complexes [PtMe2(NN)] {NN=5,5′-Me2bpy (5,5′-dimethyl-2,2′-bipyridine; phen (1,10-phenanthroline)} were reacted with benzyl bromide to yield the organoplatinum(IV) complexes [PtMe2(PhCH2)Br(NN)] {NN=5,5′-Me2bpy (1), phen (2)}. On the basis of NMR data, the Pt(IV) products of 1–2 contain almost exclusively the trans isomer and small traces of the cis isomers are also observed. Oxidative addition of dimethylplatinum(II) complexes [PtMe2(NN)] with dihaloalkanes CH2Cl2 and Br(CH2)4Br have also been investigated. The reactions of complexes [PtMe2(NN)] {NN=4,4′-Me2bpy (4,4′-dimethyl-2,2′-bipyridine); 5,5′-Me2bpy; phen} with dihaloalkanes CH2Cl2 and Br(CH2)4Br resulted in the formation of the new organoplatinum(IV) complexes [PtMe2(CH2Cl)Cl(NN)] {NN=4,4′-Me2bpy (3); 5,5′-Me2bpy (4)} and [PtMe2{(CH2)4Br}Br(NN)] {NN=4,4′-Me2bpy (5); 5,5′-Me2bpy (6); phen (7)}, respectively. The products have been characterized by elemental analysis, 1H, 13C, HH-COSY and DEPT-135 NMR spectroscopy. On the basis of NMR data, in the case of CH2Cl2, the platinum(IV) products of the reaction contain a mixture of cis and trans isomers, while small traces of the cis isomer are observed in the case of Br(CH2)4Br. NMR data indicates that the trans influence of bpy, 4,4′-Me2bpy and 5,5′-Me2bpy is the same. The crystal structures of [PtMe2(CH2Cl)Cl(4,4′-Me2bpy)] and [PtMe2{(CH2)4Br}Br(4,4′-Me2bpy)] reveal a slightly distorted octahedra