Reactivity of SiMe₃- and SnR₃-Functionalized Bis(7-azaindol-1-yl)methane with [PtR₂(μ-SMe₂)]_n (R = Me, Ph) and the Resulting Pt(II) and Pt(IV) Complexes

Three new bis(7-azaindol-1-yl)methane (BAM) derivative ligands Me₃Si-BAM (1a), Me₃Sn-BAM (1b), and Ph₃Sn-BAM (1c) have been synthesized, and their reactivities with [PtR₂(μ-SMe₂)]_n (R = Me, Ph) have been examined. Two Pt(II) complexes Pt(Me₃Si-BAM)R₂ (R = Me, 2; Ph, 3) were obtained from the reactions of 1a. The reactions of 1b with [PtR₂(μ-SMe₂)]_n (R = Me, Ph) produced unexpected novel N,C,N-BAM Pt(IV) complexes Pt(N,C,N-BAM)(SnMe₃)R₂ (R = Me, 4; Ph, 6) likely via oxidative cleavage of the C_BAM−Sn bond in 1b. 1c reacted with [PtPh₂(μ-SMe₂)]_n (n = 2, 3) yielding the anticipated Pt(II) complex Pt(Ph₃Sn-BAM)Ph₂ (7), whereas its reaction with [PtMe₂(μ-SMe₂)]₂ resulted in unusual Pt^II-Me and Sn^IV-Ph metathesis, yielding also 7 as one of the products. Mechanistic investigation was carried out to understand this phenomenon. The reactivities of 2 with MeI, MeOTf, and I₂ were examined. Its reaction with I₂ gave rise to Pt(Me₃Si-BAM)I₂ (9) along with CH₃I, indicating the possibility of functionalizing Pt^II-Me via iodinolysis. The reaction of Pt(N,C,N-BAM)(SnMe₃)Me₂ (4) with I₂ produced a number of unusual N,C,N-BAM Pt(IV) complexes including Pt(N,C,N-BAM)Me(I)(SnI₂Me) (13) and Pt(N,C,N-BAM)Me(I)(I₃) (14) due to the electrophilic cleavage of the Sn-Me, Pt-Me and/or Pt−Sn bond(s) by I₂. For comparison, we also investigated the reaction of Pt(N,C,N-BAM)Me₃ (M1) with I₂ which was found to exhibit a high regioselectivity for the axial Pt-Me group, resulting in Pt(N,C,N-BAM)Me₂(I₃) (15) with the two Pt-Me being cis to each other. The reactions of 4 and M1 with I₂ are rare examples of Pt^IV−CH₃ bond cleavage by the elimination of CH₃I. The structures of 1a and complexes 2, 7, 9, and 13−15 were determined by X-ray diffraction analyses.