Synthesis and Solid-State Structure of (4-Hydroxy-3,5-diiodophenyl) phosphine Oxides. Dimeric Motifs with the Assistance of O-H•••O=P Hydrogen Bonds

(4-Hydroxy-3,5-diiodophenyl)diphenylphosphine oxide, bis(4-hydroxy-3,5-diiodophenyl)(phenyl) phosphine oxide, and tris(4-hydroxy-3,5-diiodophenyl)phosphine oxide were obtained via iodination reactions of corresponding mono-, bis-, and tris(4-hydroxyphenyl)phosphine oxides. Single-crystal X-ray diffraction studies showed each homologue forms O-H center dot center dot center dot O=P and pi-stacking interactions with neighboring molecules to give inversion related dimeric motifs.