1,8‐Bis(phosphanyl)naphthalenes: 1,8‐Bis[(diethylamino)phosphanyl]‐naphthalene, 1,8‐Bis(dichlorophosphany)naphthalene, and 1, 3‐Dichloro‐2,‐3‐dihydro‐1,3‐dioxo‐2‐oxa‐1,3‐diphosphaphenalene

Abstract 1.8‐dilithionaphthalene 1 reacted with bis(dimethylamino)‐chlorophosphane to form 1,8‐bis[(diethylamino)phosphanyl]‐naphthalene 2, whose structure was confirmed by X‐ray crystal structure analysis; there are two independent molecules, in which the P(NEt2)2 groups adopt an eclipsed conformation. Reaction of 2 with gaseous HCl gave in low yield 1,8‐bis‐(dichlorophosphanyl)naphthalene 3, which was characterized by 1H‐ and 31P‐NMR spectroscopy, mass spectrometry and elemental analysis. Attempted recrystallization of 3 led to oxidative hydrolysis which furnished 4, an anhydride of a bis(chlorophosphonic acid), whose structure was elucidated by X‐ray crystal structure analysis. The geometry of 4 reveals a relief of strain from the bis (aminophosphane) 2; the naphthalene groups are less distorted and the P atoms are displaced less far from the naphthalene best plane.