Abstract

The crystallisation, crystal structures, and crystal packing analyses of [Fe(phen)₃]I₁₄ and [Fe(phen)₃]I₁₈ are reported (phen⊕=⊕1,10-phenanthroline). [Ni(phen)₃]I₁₈ and [Fe(phen)₃]I₁₈ are isomorphous. These three compounds crystallise from iodine-rich solutions, and as crystals are relatively stable to loss of I₂ over periods of weeks. Crystalline [Fe(phen)₃]I₁₄ contains parallel fourfold aryl embracing (P4AE) pairs of [Fe(phen)₃]²⁺ complexes, while in [Fe(phen)₃]I₁₈ all embraces between metal complexes are disrupted. The filled aryl box motif (FAB) that occurs in [Fe(phen)₃]I₁₄ is comprised of four phen ligands from two complexes forming a four-sided orthogonal box, through which an approximately linear I₆ chain is threaded. The extended polyiodide nets in each crystal demonstrate the continuum of I–I distances characteristic of a flat energy potential, and it is concluded that the dimensions of the polyiodide nets are influenced strongly by their association with the [Fe(phen)₃]²⁺ complexes, and should not be otherwise deconstructed. Polyiodide sequences wrap the phen ligands, closely and effectively, running along their faces, in the grooves between them, and around their peripheries. The approximately linear C–H⋯I motif recurs at the edges of the ligand planes, and is evidently significant. The polyiodide U-clamp on a phen ligand is a prevalent motif. These structures demonstrate well the complementary orthogonality of the ligands in [M(phen)₃] complexes with the angles and dihedral angles in extended polyiodide nets.