Solubilizing Sodium Fluoride in Acetonitrile: Synthesis, Molecular Structure, and Complexation Behavior of Bis(organostannyl)methyl-Substituted Crown Ethers

The synthesis of the crown‐ether‐substituted bis(organostannyl)methanes Ph3SnCH2Sn(Ph2)‐CH2‐[16]crown‐5 (1) and Ph2ISnCH2Sn(I)(Ph)‐CH2‐[16]crown‐5 (2) is reported. Both compounds have been characterized by elemental analyses, 1H, 13C, 19F, and 119Sn NMR spectroscopy, and in the case of compound 2 also by electrospray ionization mass spectrometry. Single‐crystal X‐ray diffraction analysis revealed for the aqua complex 2⋅H2O trigonal–bipyramidal‐configured tin atoms with intramolecular Sn(1)O(1) and Sn(2)O(1W) distances of 2.555(2) and 2.440(3) Å, respectively. The water molecule is trapped in a sandwich‐like fashion between the crown ether oxygen atoms O(2) and O(4) and the Sn(2) atom. NMR spectroscopy unambiguously proved the ability of compound 2 in acetonitrile to overcome the high lattice energy of sodium fluoride and to complex the latter under charge separation. Two birds with one stone: The combination of a crown ether and a bicentric Lewis acidic organotin moiety gives a stable heteroditopic receptor 1 that simultaneously binds the cation and anion in sodium fluoride in organic solvents (see picture).