Syntheses and crystal structures of organoindium(III) 1-D coordination polymers with bis(diphenylphosphino)alkane dioxides

Bromomethyl-dibromo-indium(III), Br₂InCH₂Br, obtained from indium monobromide and methylene dibromide, reacts with hard and soft donor ligands to afford the corresponding indium(III) organometallic complexes. In this work, we investigated the conditions to prepare adducts of Br₂InCH₂Br using bis(diphenylphosphino)alkane dioxides acting as hard ligands. We report here the synthesis and crystal structures of two 1-D coordination polymers with the hard donor ligands Ph₂P(O)(CH₂)_mP(O)Ph₂ (m = 2, dppeO₂ and m = 6, dpphO₂). Compounds 1 and 2 with formulas [Br₂In(CH₂Br)(dppeO₂)]_n (1) and [Br₂In(CH₂Br)(dpphO₂)]_n (2) were characterized by IR and Raman spectroscopy and elemental analysis. We also obtained an ionic indium(III) compound with dppeO₂ acting as a chelating ligand with formula [InBr₂(dppeO₂)₂][InBr₃(CH₂Br)] (3). The crystal structures were determined for 1–3 using single crystal X-ray diffractometry. The geometry around the In(III) can be described as a trigonal bipyramid in 1 and 2, and the chains were packed onto the plane giving layers that are stabilized mainly by intermolecular interactions. Compound 3 has a square bipyramidal In(III) cation with formula [Br₂L₂In]⁺ and tetrahedral organoindium(III) anion with formula [Br₃InCH₂Br]^–. Hirshfeld surface analysis employing 2-D fingerprint plots have been used to analyze intramolecular and intermolecular interactions present in the solid state of the structures.