Salts of the Dianions [Hg(12-X-<i>closo</i>-1-CB₁₁H₁₀)₂]^2– (X = I, CCH, CCFc, CCSi<i>i</i>Pr₃): Synthesis and Spectroscopic and Structural Characterization

Cesium or tetraethylammonium salts of the doubly negatively charged mercury­(II) complexes [Hg­(12-I-closo-1-CB11H10)2]2– (1), [Hg­(12-HCC-closo-1-CB11H10)2]2– (2), [Hg­(12-FcCC-closo-1-CB11H10)2]2– (3), and [Hg­(12-iPr3SiCC-closo-1-CB11H10)2]2– (4) were synthesized. The synthesis of the alkynyl-functionalized clusters was conducted via two different routes. The alkynyl moiety either was present before formation of the mercury­(II) complex or was introduced via a Pd-catalyzed cross-coupling reaction using Cs21 as starting material. The compounds were characterized by multi-NMR and vibrational spectroscopy, mass spectrometry, and elemental analysis. Gas-phase reactions of the dianions 1, 2, and 3 were studied by collision-induced dissociation in (−)-ESI mass spectrometry experiments. Single crystals of Cs21·2MeCN, Cs21·xMe2CO (x ≈ 2), [Et4N]22·yEt2CO (y ≈ 4), and [Et4N]23 were studied by X-ray diffraction. In the crystals of Cs21·xMe2CO (x ≈ 2) the dianions and half of the Cs+ cations form a stacked hexagonal structure with channels that contain the second half of the Cs+ cations and the solvent molecules. The formation of this supramolecular structure is rationalized by weak Hg···I and Cs···I interactions that are close to classical van der Waals interactions.