Computational Study of Bridge Splitting, Aryl Halide Oxidative Addition to PtII, and Reductive Elimination from PtIV: Route to Pincer‐PtII Reagents with Chemical and Biological Applications.

Density functional theory computation indicates that bridge splitting of [PtIIR2(μ‐SEt2)]2 proceeds by partial dissociation to form R2Pta(μ‐SEt2)PtbR2(SEt2), followed by coordination of N‐donor bromoarenes (L‐Br) at Pta leading to release of PtbR2(SEt2), which reacts with a second molecule of L‐Br, providing two molecules of PtR2(SEt2)(L‐Br‐N). For R=4‐tolyl (Tol), L‐Br=2,6‐(pzCH2)2C6H3Br (pz=pyrazol‐1‐yl) and 2,6‐(Me2NCH2)2C6H3Br, subsequent oxidative addition assisted by intramolecular N‐donor coordination via PtIITol2(L‐N,Br) and reductive elimination from PtIV intermediates gives mer‐PtII(L‐N,C,N)Br and Tol2. The strong σ‐donor influence of Tol groups results in subtle differences in oxidative addition mechanisms when compared with related aryl halide oxidative addition to palladium(II) centres. For R=Me and L‐Br=2,6‐(pzCH2)2C6H3Br, a stable PtIV product, fac‐PtIVMe2{2,6‐(pzCH2)2C6H3‐N,C,N)Br is predicted, as reported experimentally, acting as a model for undetected and unstable PtIVTol2{L‐N,C,N}Br undergoing facile Tol2 reductive elimination. The mechanisms reported herein enable the synthesis of PtII pincer reagents with applications in materials and bio‐organometallic chemistry. [ABSTRACT FROM AUTHOR]