Expanded Halogen-Bonded Anion Organic Networks with Star-Shaped lodoethynyl-Substituted Molecules: From Corrugated 2D Hexagonal Lattices to Pyrite-Type 2-Fold Interpenetrated Cubic Lattices

摘要

Halogen bonding interactions between halide anions and neutral polyiodinated linkers are used for the elaboration of anion organic frameworks, by analogy with well-known MOF derivatives.The extended, 3-fold symmetry, 1,3,5-tris(iodoethynyl)-2,4,6-trifluo-robenzene (1) cocrystallizes with a variety of halide salts, namely,Et_3S~+I~-, Et_3MeN~+I~-, Et_4N~+Br~-, Et_3BuN~+Br~-, Me-DABCO~+I~-,Bu_3S~+I~-, Bu_4N~+Br~-, Ph_3S~+Br~-, Ph_4P~+Br~-, and PPN+Br~-. Salts with 1:1 stoichiometry formulated as (1)·(C +,X~-) show recurrent formation of corrugated (6,3) networks, with the large cavities thus generated, filled either by the cations and solvent (CHCl_3) molecules and/or by interpenetration (up to 4-fold interpenetration). The 2:1 salt formulated as (1)_2·(Et_3BuN~+Br~-) crystallizes in the cubic Ia3 space group (a = 22.573(5) A, V = 11502(4) A~3), with the Br~- ion located on 3 site and molecule 1 on a 3-fold axis. The 6-fold, unprecedented octahedral coordination of the bromide anion generates an hexagonal three-dimensional network of Pa3 symmetry, as observed in the pyrite model structure, at variance with the usual, but lower-symmetry, rutile-type topology. In this complex system, the I centering gives rise to a 2-fold interpenetration of class Ia, while the cations and solvent molecules are found disordered within interconnected cavities. Another related cubic structure of comparable unit cell volume (space group Pa3, a = 22.4310(15) A, V = 11286.2(13) A~3) is found with (1)_2·(Et_3S~+I~-).