Reaction of bis (morpholinoselenocarbonyl) triselenide with iodine. Existence of a 1 : 1 charge-transfer precursory adduct in solution in an oxidative reaction. Isolation and crystal structure of the new (N-morphoilnecarbodiselenoato)selenium(II)iodide

Abstract

The reaction of bis(morpholinoselenocarbonyl) triselenide, Se₃[C(Se)NC₄H₈O]₂ with iodine in CH₂Cl₂ has been investigated employing spectrophotometric measurements. Working with an excess of iodine, spectral features indicate the formation of a very stable 1 : 1 charge-transfer adduct. This species evolves [k_c=(10.1 ± 0.6)× 10^–6 s^–1 at 25 °C] and from the solution the new red-brown compound (morpholinecarbodiselenoato)selenium(II) iodide, [OC₄H₈NCSe₃]I, was isolated. Working with an excess of Se₃[C(Se)NC₄H₈O]₂ spectral results suggest the existence of an equilibrium between the 1 : 1 adduct and Se₃[C(Se)NC₄H₈O]₂, which yields products having a spectrum very similar to that of [OC₄H₈NCSe₃]I. The compound [OC₄H₈NCSe₃]I was recovered also from the solutions of these mixtures. Crystals of the product are monoclinic, space group P2₁/c, with a= 8.62(5), b= 17.19(6), c= 14.59(6)Å, β= 101.1(1)°, and Z= 8. The structure consists of polymeric ⋯ I ⋯ Se ⋯ Se ⋯ I ⋯ chains running along c held together by van der Waals contacts.