Reactivity of Diaryliodine(III) Triflates toward Palladium(II) and Platinum(II): Reactions of C(sp2)-I Bonds to Form Arylmetal(IV) Complexes; Access to Dialkyl(aryl)metal(IV), 1,4-Benzenediyl-Bridged Platinum(IV), and Triphenylplatinum(IV) Species; and Structural Studies of Platinum(IV) Complexes

Abstract

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, [IPh2][OTf] reacts with PtMe2(bpy) (bpy = 2,2'-bipyridine) at -50 degrees C to form iodobenzene and the Pt(IV) complex trans-PtIV(OTf)Me2Ph(NN) (1b) (Ph trans to OTf), and on addition of NaI, the species PtIMe2Ph(bpy) (2a (Ph cis to I) and 2b (Ph trans to I) in 2:1 ratio) may be isolated at -20 degrees C. Similarly, metalla-(II)cyclopentane complexes M(C4H8)(bpy) react with [IPh2][OTf] to form trans-Pt(OTf)(C4H8)Ph(bpy) (3b) and a 1:1 ratio of cis- (4a) and trans-Pd(OTf)(C4H8)Ph(bpy) (4b); addition of halide ion gives trans-PtI(C4H8)Ph(bpy) (5b) and a 1:3 ratio of cis and trans isomers for PdI(C4H8)Ph(bpy) (6a, 6b) and PdCl(C4H8)Ph(bpy) (7a, 7b). Complex 5b isomerizes to form a 2:1 mixture of cis-PtI(C4H8)Ph(bpy) (5a) and 5b at ambient temperature in acetone. Dimethyl(2,2'-bipyridine)palladium(II) reacts with [IPh2][OTf] to form Pd(OTf)Me2Ph(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(C6H4-4-I)][OTf], followed by addition of sodium iodide, to form a 1:1 mixture of trans-PtIMe2Ph(bpy) (2b) and trans-PtIMe2(C6H4-4-I)(bpy) (8b), and with [IPh(C6H4-4-IPh)][OTf]2 to form the 1,4-arenediyl complex trans-1,4-{PtIMe2(bpy)}2C6H4 (9b). Diphenyl{di(tert-butyl)-2,2'-bipyridine}platinum(II) reacts with [IPh2][OTf] at 25 degrees C over 2 days to form the triphenylplatinum(IV) complex Pt(OTf)Ph3(But2bpy)(10), and addition of iodide ion results in isolation of PtIPh3(But2bpy)(11). Structural studies of trans-PtIMe2Ph(bpy) (2b) and trans-Pt(C4H8)Ph(bpy) (5b) reveal distorted octahedral geometry and the fac-PtC3 configuration expected for all of the metal(IV) complexes. The compound [IPh(C6H4-4-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 degrees.