Complexes of Bidentate Phosphane Selenide Ligands with Mesitylenetellurenyl Iodide and with Tellurium Diiodide

摘要

Bis(diphenylphosphanyl)methane diselenide (dppmSe_2,1) and bis(diphenylphosphanyl)ethane diselenide (dppeSe_2,2) reacted with 2 equiv.Br_2 or I_2 to form the insoluble solid products,dppm(SeX_2)_2 (X = Br,3; X = I,4) and dppe(SeX_2)_2 (X = Br,5; X = I,6).However,using the iodine-like electro-phile mesitylenetellurenyl iodide (MesTel,7),fairly soluble complexes,dppmSe_2[Te(I)Mes]_2 (8) and dppeSe_2[Te(I)Mes]_2 (9),were obtained.Complexes 8 and 9 contain two T-shaped (10-Te-3) Se-Te(Mes)-I moieties bridged by dppm or dppe; solid 9 exhibits intermolecular soft-soit interactions between approximately linear Se-Te-I units.In a side reaction accompanying the crystallisation of complex 8,or by the reaction of 1 with Te and I_2,a chelate complex dppmSe_2TeI_2 (10) was formed.Fortuitously,a crystal of the related compound dppeSe_2TeI_2 (11) was also obtained.In 10,a square planar cis-Se_2TeI_2 group is part of a six-membered ring,and 11 is a coordination polymer with trans-Se_2TeI_2 moieties bridged by dppe.Averaged ~(31)P- and ~(77)Se NMR signals including ~(77)Se-~(31)P couplings,together with broad ~(125)Te NMR singlets indicate phosphane selenide ligand exchange in solution,that is,the kinetically labile behaviour of complexes 8 and 9.