Diaryliodonium Tetrachloroplatinates(II): Recognition of a Trifurcated Metal-Involving μ3-I···(Cl,Cl,Pt) Halogen Bond

Synthesis and X-ray characterization of the four diaryliodonium tetrachloroplatinates(II) [Ar1Ar2I]2[PtCl4] (Ar1/Ar2 = Ph/Ph (1), 4-Cl-C6H4/2,4,6-(MeO)3C6H2 (2), 4-Me-C6H4/2,4,6-(MeO)3C6H2 (3), Ph/2,4,6-(MeO)3C6H2 (4)) allowed the deterimination of several types of unconventional halogen-bond (HaB) patterns. The first example of a metal-involved trifurcated four-center μ3-X···(X′,X′,M) HaB is represented by the metal-involving I···Pt HaB (the structure of 4) with iodonium cations acting as HaB donors, which is supported by two weak I···Cl HaB contacts. The structures of 1-3 display bifurcated three-center μ2-I···(Cl,Cl) HaBs with iodonium cations. DFT calculations were used to estimate the energetic features of the two types of HaB contacts. Molecular electrostatic potential (MEP) surfaces and noncovalent interaction plot index (NCIPlot) computational tools were used to evaluate the σ-holes and characterize the HaBs, respectively, in all structures.