Hydrocarbon-Soluble Mercuracarborands:  Syntheses, Halide Complexes, and Supramolecular Chemistry

• Published in: Inorganic chemistry 1996-02, Vol.35 (5), p.1235-1243
• Main Authors: Zheng, Zhiping, Knobler, Carolyn B, Mortimer, Mark D, Kong, Gapgoung, Hawthorne, M. Frederick
• Format: Article
• Language: English
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/ic951069o

The syntheses of macrocyclic species composed of carborane derivatives joined via their carbon vertices by electrophilic mercury atoms are described. The reaction of closo-1,2-Li2[C2B10H10 - x R x ] with HgI2 gives Li2[(1,2-C2B10H10 - x R x Hg)4I2] [R = Et, x = 2 (5·I2Li2); R = Me, x = 2 (6·I2Li2); R = Me, x = 4 (7·I2Li2)]. 6·I2(K·[18]dibenzocrown-6)2 crystallizes in the monoclinic space group C2/m [a = 28.99(2) Å, b = 18.19(1) Å, c = 13.61(1) Å, β = 113.74(2)°, V = 6568 Å3, Z = 4, R = 0.060, R w = 0.070]; 7·I2(NBu4)2 crystallizes in the monoclinic space group P21/c [a = 12.77(1) Å, b = 21.12(2) Å, c = 20.96(2) Å, β = 97.87(2)°, V = 5600 Å3, Z = 2, R = 0.072, R w = 0.082]. The precursor to 7, closo-8,9,10,12-Me4-1,2-C2B10H8 (4), is made in a single step by reaction of closo-1,2-C2B10H12 with MeI in trifluoromethanesulfonic acid. The free hosts 5, 6, and 7 are obtained by reaction of the iodide complexes with stoichiometric quantities of AgOAc. A 199Hg NMR study indicates that sequential removal of iodide from 5·I2Li2 and 6·I2Li2 with aliquots of AgOAc solution leads to formation of two intermediate host−guest complexes in solution, presumed to be 5(6)ILi and 5 2(6)2·ILi. Crystals grown from a solution of 6·I2Li2 to which 1 equiv of AgOAc solution had been added proved to be an unusual stack structure with the formula 6 3·I4Li4 [tetragonal, I4/m, a = 21.589(2) Å, c = 21.666(2) Å, V = 10098 Å3, Z = 2, R = 0.058, R w = 0.084]. Addition of 2 equiv of NBu4Br ion to 5 or 6 gives 5·Br2(NBu4)2 and 6·Br2(NBu4)2, respectively, while addition of 1 equiv of KBr to 6 forms 6·BrK. 5·Br2(NBu4)2 crystallizes in the triclinic space group P1̄, [a = 10.433(1) Å, b = 13.013(1) Å, c = 15.867(2) Å, α = 91.638(2)°, β = 97.186(3)°, γ = 114.202(2)°, V = 1492 Å3, Z = 1, R = 0.078, R w = 0.104]. The hosts 5 and 6 form 1:1 supramolecular adducts with the polyhedral anions B10I10 2- and B12I12 2- in solution.