Salts of the Dianions [Hg(12-X-closo-1-CB11H10)2]2- (X = I, CCH, CCFc, CCSiiPr3): 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-iPr(3)SiC 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 Cs(2)1 center dot 2MeCN, Cs(2)1 center dot xMe(2)CO (x approximate to 2), [Et4N](2)2 center dot yEt(2)CO (y approximate to 4), and [Et4N](2)3 were studied by X-ray diffraction. In the crystals of Cs(2)1 center dot xMe(2)CO (x approximate to 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 center dot center dot center dot I and Cs center dot center dot center dot I interactions that are close to classical van der Waals interactions.