Comparison of divalent dimethoxyethane-solvated thulium and samarium diiodides in hexamethylphosphoramide and pyridine: Isolation of the cations { [TmI2 (HMPA) 4] [I] (pyridine) 5} and { [TmI (HMPA) 4 (pyridine) ] [I] 2} and a single crystal containing both linear and bent dimethoxyethane-solvated SmI2

Abstract

The highly reducing nature of TmI2 (DME) 3 is shown by comparison with SmI2 in its reactions in hexamethylphosphoramide (HMPA) and pyridine. Addition of 4 equiv. of HMPA to green TmI2 (DME) 3 in dimethoxyethane (DME) forms pale yellow solids which dissolve in pyridine and can be isolated as TmI3 (HMPA) 4, 1. Recrystallization of 1 from pyridine yields { [TmI2 (HMPA) 4] [I] (pyridine) 5} , 2, or { [TmI (HMPA) 4 (pyridine) ] [I] 2} , 3, depending upon conditions. Both 2 and 3 crystallize with distorted octahedral geometries around thulium. Addition of HMPA to TmI3 in DME also forms 1. TmI2 (DME) 2, formed by the loss of DME from TmI2 (DME) 3 under vacuum, reacts with pyridine to form intensely colored materials, which have magnetic moments consistent with the presence of Tm (III) . In comparison, SmI2 (THF) 2 dissolves in a mixture of pyridine and DME and can be recrystallized as divalent SmI2 (DME) 3, 4. 4 crystallizes with both linear and bent I-Sm-I arrangements in the same crystal. In the former case a hexagonal bipyramidal coordination geometry is present and in the latter a dodecahedral geometry is observed.