| Title
| - Access to Alkynylpalladium(IV) and -Platinum(IV) Species,Including Triorgano(diphosphine)metal(IV) Complexes and theStructural Study of an Alkynyl(pincer)platinum(IV) Complex,Pt(O2CArF)I(C⋮CSiMe3)(NCN) (ArF = 4-CF3C6H4, NCN =[2,6-(dimethylaminomethyl)phenyl-N,C,N]-)
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| Abstract
| - New classes of alkynylplatinum(IV) complexes are described, and the first examples of alkynylpalladium(IV) complexes have been detected, including a triorganopalladium(IV) diphosphine complex.Alkynyliodine(III) triflate reagents IPh(C⋮CR2)(OTf) (R2 = SiMe3, Ph) are able to transfer alkynyl groupsto diorganoplatinum(II) and “pincer” complexes Pt(O2CAr)(NCN) (NCN = [2,6-(dimethylaminomethyl)phenyl-N,C,N]-, Ar = Ph, 4-trifluoromethylphenyl (ArF)); on addition of iodide ion, complexes withnew alkynylplatinum(IV) kernels may be isolated: PtIMe2(C⋮CR2)(bpy) (1, 2, 3a) (bpy = 2,2‘-bipyridine),PtI(C4H8)(C⋮CSiMe3)(bpy) (4a), PtIPh2(C⋮CSiMe3)(But2bpy) (5a), and PtI(O2CAr)(C⋮CR2)(NCN) [Ar= Ph (14, 15), ArF (16, 17)]. For the reagent PtMe2(dmpe) [dmpe = 1,2-bis(dimethylphosphino)ethane],the unstable complexes PtIMe2(C⋮CR2)(dmpe) (6a, 8a) are detected prior to reductive elimination ofethane and isolation of PtI(C⋮CR2)(dmpe) (7, 9). Isomerism is exhibited by the octahedral fac-PtIVR2(C⋮CR2) complexes, where complexes 1 and 2 form as a mixture of complexes with the alkynyl groupopposite the bidentate ligand and cis to the iodo ligand (1a−6a, 8a), and cis to the bidentate ligand andtrans to the iodo ligand (1b, 2b), complexes 3a−5a, 6a, and 8a having R groups mutually cis. An X-raystructural analysis for 16 shows distorted octahedral geometry about the metal with the iodo ligand transto the carbon donor of the mer-pincer ligand. Studies of the reactivity of related palladium(II) substratesat low temperature allow detection of the pincer complex Pd(O2CPh)(OTf)(C⋮CSiMe3)(NCN) (19) andPdIMe2(C⋮CSiMe3)(dmpe) (18) as a model for frequently proposed “PdIVXR3P2” species in catalyticand stoichiometric reactions.
- New classes of alkynylplatinum(IV) complexes are described, and the first examples of alkynylpalladium(IV) complexes have been detected, including a triorganopalladium(IV) diphosphine complex.
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