A surprise landing on the terra incognita of macrocyclic dibridgehead diorganoarsines: syntheses, structures, and reactivities.

Reactions of trans -[Fe(CO) 2 (NO)(As((CH 2 ) n ) 3 As)] + BF 4 - ( n = 10, 12, 14) and Bu 4 N + Cl - afford the title compounds As((CH 2 ) n ) 3 As, which upon reaction ( n = 14) with MCl 2 (M = Pt, Ni), Rh(CO)(Cl), and Fe(CO) 3 sources reconstitute cage like complexes trans -ML n (As((CH 2 ) 14 ) 3 As). Reactions with H 2 O 2 and BH 3 give the corresponding arsine oxides and boranes. Crystal structures of metal-free species reveal out , out isomers, but cage complex formation is proposed to entail homeomorphic isomerization to in , in isomers with endo directed lone pairs.