A study of the reaction of PtMe(2)(bipy) with IPh(C[triple bond]CSiMe(3))(OTf) at low temperature in acetone, leading to detection of the Pt-Pt-bonded cation [Pt(2)Me(4)(C[triple bond]CSiMe(3))(bipy)(2)](+), an intermediate in the oxidation of Pt(II) to Pt(IV), is reported. The cation is assessed as Pt(III)-Pt(III) <--> Pt(IV)-Pt(II), and at the other extreme may be regarded as a cationic alkynylplatinum(IV) center, "[Pt(IV)Me(2)(C[triple bond]CSiMe(3))(bipy)](+)", stabilized by "Pt(II)Me(2)(bipy)" as a donor ligand. The detection and isolation of the [Pt(2)Me(4)(C[triple bond]CSiMe(3))(bipy)(2)](+) cation provides a number of insights into the mechanisms of oxidation reactions.
Diphenyliodine(III) triflate is able to transfer Ph + to Pd(II) and Pt(II) with cleavage of a phenyl-iodine bond and formation of metal(IV) species, leading to the first identified transfer of Ph + to Pd(II) from an aryl-halogen bond, and, for platinum, a methodology providing a facile route to dimethyl(aryl)platinum(IV) and 1,4-arenediyl-bridged Pt(IV) species and the first archetypal triarylplatinum(IV) complex. Thus, [IPh 2 ][OTf] reacts with PtMe 2 (bpy) (bpy ) 2,2′-bipyridine) at -50°C to form iodobenzene and the Pt(IV) complex trans-Pt IV (OTf)Me 2 -Ph(N∼N) (1b) (Ph trans to OTf), and on addition of NaI, the species PtIMe 2 Ph(bpy) (2a (Ph cis to I) and 2b (Ph trans to I) in 2:1 ratio) may be isolated at -20°C. Similarly, metalla-(II)cyclopentane complexes M(C 4 H 8 )(bpy) react with [IPh 2 ][OTf] to form trans-Pt(OTf)(C 4 H 8 )-Ph(bpy) (3b) and a 1:1 ratio of cis-(4a) and trans-Pd(OTf)(C 4 H 8 )Ph(bpy) (4b); addition of halide ion gives trans-PtI(C 4 H 8 )Ph(bpy) (5b) and a 1:3 ratio of cis and trans isomers for PdI(C 4 H 8 )Ph(bpy) (6a, 6b) and PdCl(C 4 H 8 )Ph(bpy) (7a, 7b). Complex 5b isomerizes to form a 2:1 mixture of cis-PtI(C 4 H 8 )Ph(bpy) (5a) and 5b at ambient temperature in acetone. Dimethyl(2,2′-bipyridine)palladium(II) reacts with [IPh 2 ][OTf] to form Pd(OTf)Me 2 Ph(bpy), followed by transfer of a methyl group from Pd(IV) to Pd(II), to form trimethylpalladium-(IV) species. Dimethyl(2,2′-bipyridine)platinum(II) reacts with [IPh(C 6 H 4 -4-I)][OTf], followed by addition of sodium iodide, to form a 1:1 mixture of trans-PtIMe 2 Ph(bpy) (2b) and transPtIMe 2 (C 6 H 4 -4-I)(bpy) (8b), and with [IPh(C 6 H 4 -4-IPh)][OTf] 2 to form the 1,4-arenediyl complex trans-1,4-{PtIMe 2 (bpy)} 2 C 6 H 4 (9b). Diphenyl{di(tert-butyl)-2,2′-bipyridine}platinum-(II) reacts with [IPh 2 ][OTf] at 25°C over 2 days to form the triphenylplatinum(IV) complex Pt(OTf)Ph 3 (Bu t 2 bpy) (10), and addition of iodide ion results in isolation of PtIPh 3 (Bu t 2 bpy) (11). Structural studies of trans-PtIMe 2 Ph(bpy) (2b) and trans-Pt(C 4 H 8 )Ph(bpy) (5b) reveal distorted octahedral geometry and the fac-PtC 3 configuration expected for all of the metal-(IV) complexes. The compound [IPh(C 6 H 4 -4-I)][OTf] has two sets of cation-anion pairs with a complex array of weak interactions, and the cations have C-I-C angles close to 90°.
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