The crystal packing of [M(phen)3]I7 (M = Mn, Fe)
Abstract
The crystallisation, crystal structures, and crystal packing of [Mn(phen)3]I7 and [Fe(phen)3]I7 are reported. The crystal lattices are isomorphous, but there are informative small differences between the two structures. The [M(phen)3]2+ complexes occur as parallel (P4AE)∞ chains, forming two parallel fourfold aryl embraces (P4AE) with adjacent cations. The polyiodide components occur between the chains, and in the (phen)2 grooves of the complexes. The stoichiometry {I7}2- is comprised structurally of discrete I3- and half of centrosymmetric [I8]2- units. These [I8]2- units contain twofold 50:50 disorder, and are either zig-zag I82-, or I2 plus I62-. Details of the disorder are different in the two crystals, reflecting the soft I...I potentials involved. The I82- ion is normal, but the I62- species, as a centrosymmetric pair of linear I3-, appears to be unprecedented. The disordered polyiodide segments are positioned in a filled aryl box motif formed by (phen)2 grooves from complexes in adjacent (P4AE)∞ chains. These crystal structures illustrate again the pattern of complementary orthogonality of phen ligands and polyiodide segments