Exchange of halogens in the 3a,6a-diaza-1,4-diphosphapentalene derivatives: Crystal structures of iodides

1,4-Dichloro-3a,6a-diaza-1,4-diphosphapentalene (II) easily exchanges halogen with methyl iodide to form the corresponding 1,4-diiodo derivative (V) in a quantitative yield. The reaction of compound II with diiodine (1 equiv) affords compound III, the crystal structure of which contains 55% II and 45% V. Under the conditions of iodine excess (1 : 3), a ionic compound (IV) is formed, the crystal of which contains alternating layers consisting of planar networks I₂I₃]? and heterocyclic cations DDP–Cl]⁺. For the crystallographic information for compounds III–V, see CIF files CCDC no. 1560 410 (V), 1560 411 (III), and 1560 412 (IV).