Diaryliodonium as a double sigma-hole donor: the dichotomy of thiocyanate halogen bonding provides divergent solid state arylation by diaryliodonium cations

摘要

X-ray crystallography data revealed the dichotomy of thiocyanate-involving noncovalent interactions in [(ArArI)-Ar-1-I-2](SCN), as reflected in the generation of two types of supramolecular aggregates: (i) previously unreported 4-membered heterotetramers (Ar-1/Ar-2= 4-ClC6H4/2,4,6-(MeO)(3)C6H2, 4-BrC6H4/2,4,6-(MeO)(3)C6H2; 2 examples) featuring exclusively halogen bond (XB)N-XB-bound SCN(-)anions, and (ii) the 8-membered cyclic heterotetramers (Ar-1/Ar-2= Ph/Ph, Ph/2,4,6-(MeO)(3)C6H2, 4-FC6H4/2,4,6-(MeO)(3)C6H2, 3,5-Me2C6H3/4-MeOC6H4, 3,5-Me2C6H3/2,4,6-(MeO)(3)C6H2; 5 examples) with twoN,S-XB-bound thiocyanates featuring both SMIDLINE HORIZONTAL ELLIPSISI and NMIDLINE HORIZONTAL ELLIPSISI noncovalent contacts. In all cases, the I(III)centers function as a double sigma-hole donor to provide two directional XBs. The XB preorganization affects the chemoselectivity of the thiocyanate arylation in the solid-state: the heating of [(ArArI)-Ar-1-I-2](SCN) exhibiting eitherN-, orN,Spreorganized XBs leads to extremely rareN-arylation or the conventionalS-arylation, respectively. The charge-assisted XBs in [(ArArI)-Ar-1-I-2](SCN) were studied using density functional theory (DFT) calculations combined with a molecular electrostatic potential surface analysis and the quantum theory of atoms in molecules (QTAIM). Competition between theN- andN,S-XB interactions was studied, including the recognition of energy differences between the IMIDLINE HORIZONTAL ELLIPSISN and IMIDLINE HORIZONTAL ELLIPSISS contacts. The computational data were useful to rationalize the divergent solid-stateN- orS-arylation of thiocyanates.