The synthesis and Crystal structure are given for the bis (
N,
N,
N′,
N′-tetramethylethylendiammonium) octaiodo pentachloroantimonate (III) salt. An X-ray investigation has shown that the title
compound crystallizes in a monoclinic system, space group P2
1/m with the following lattice parameters
a = 9.786(2) Ǻ,
b = 14.024(5) Ǻ,
c = 14.336(3) Ǻ, β = 91.35(2)° and
Z = 2. The structure was solved from 3085 independent reflections with
R
1 = 0.0402 and
wR
2 = 0.0952 and refined with 152 parameters. The structure shows a layer arrangement perpendicular to the
[(b)\vec] \vec{b} -axis: planes of [SbCl
5]
2−, I
3
− and I
5
− anions alternate with planes of [(CH
2)
2(NH(CH
3)
2)
2]
2+ cations. The [SbCl
5]
2− square pyramids present an active lone electron pair (LEP) on the Sb atoms and they are interconnected by means of N–H···Cl
hydrogen bond originating from [(CH
2)
2(NH(CH
3)
2)
2]
2+ entities. The polyiodides (I
3
− and I
5
−) anions form a planer zigzag polymeric chains via I···I linking interactions. These chains are linked to the [SbCl
5]
2− anions by a long range contact.