Ionic-Liquid-Based Synthesis of the Germanium-Iron Carbonyls FeI4{GeI3Fe(CO)3}2 and (GeI3)2Fe(CO)4

Dark red and brick red transparent crystals of FeI4{GeI3Fe(CO)(3)}(2) (1) and (GeI3)(2)Fe(CO)(4) (2) were obtained by reacting GeI4 and Fe-2(CO)(9) or Fe-3(CO)(12) in a mixture of [BMIM]Cl and AlCl3 as ionic liquid (BMIm = 1-butyl-3-methylimidazolium). According to X-ray structure analysis based on single crystals, the title compounds exhibit cluster units with Fe-Ge bonds. FeI4{GeI3Fe(CO)(3)}(2) consists of two GeI2I1/2-Fe(CO)(3)I-2/2 units that are interlinked by a distorted octahedral FeI6/2 group. (GeI3)(2)Fe(CO)(4) consists of two GeI3 units that are connected by a square planar Fe(CO)(4) group with a linear Ge-Fe-Ge unit. Depending on the synthesis conditions, interestingly, (GeI3)(2)Fe(CO)(4) crystallizes either in P2(1)/n (2a) or in Pcontent style="text-decoration:overline">1 (2b). 2a exhibits a more dense packing, whereas 2b exhibits shorter intermolecular I-I distances. Both title compounds are temperature labile and highly sensitive to oxygen, moisture and illumination, including X-ray irradiation. They decompose with release of CO in absence of certain CO atmosphere. In addition to crystal structure analysis the compounds were characterized by energy dispersive X-ray (EDX) analysis, thermogravimetry (TG) and infrared spectroscopy (FT-IR).