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

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 electrophile mesitylenetellurenyl iodide (MesTeI, 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 – soft 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 2 TeI 2 ( 10 ) was formed. Fortuitously, a crystal of the related compound dppeSe 2 TeI 2 ( 11 ) was also obtained. In 10 , a square planar cis ‐Se 2 TeI 2 group is part of a six‐membered ring, and 11 is a coordination polymer with trans ‐Se 2 TeI 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 . (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)