Synthesis and X‐ray Structures of the Polycyclic Dimers {[PhB(μ‐N t Bu) 2 AsN( t Bu)H]LiI} 2 and [PhB(μ‐N t Bu) 2 AsN( t Bu)Li] 2

The metathesis of [PhB( μ ‐N t Bu) 2 ]AsCl and t BuN(H)Li in 1:1 molar ratio in diethyl ether produced the amido derivative [PhB(μ‐N t Bu) 2 AsN( t Bu)H] ( 1 ) in good yield. The lithiation of 1 with one equivalent of n BuLi afforded the lithium salt [PhB(μ‐N t Bu) 2 AsN( t Bu)Li] ( 2a ). Both 1 and 2a were characterized by multinuclear NMR spectroscopy. The crystal structure of 2a is comprised of a U‐shaped, centrosymmetric dimer in which the monomeric [PhB(μ‐N t Bu) 2 AsN( t Bu)] − Li + units are linked by Li‐N interactions to give a six‐rung ladder. Oxidation of 2a with one‐half equivalent of I 2 in diethyl ether resulted in hydrogen abstraction from the solvent to give the dimeric lithium iodide adduct {[PhB(μ‐N t Bu) 2 AsN( t Bu)H]LiI} 2 ( 1 ·LiI) with a central Li 2 I 2 ring.