[BMIm]2[Mn(CO)3(GeI3)3]: Carbonyl Compound with an {MnGe3} Cluster Unit.

Orange, transparent crystals of [BMIm]2[Mn(CO)3(GeI3)3] (BMIm: 1-butyl-3-methylimidazolium) are obtained by reacting GeI4, [Mn(CO)6][AlCl4], and Ph3GeH in the ionic liquid [BMIm][NTf2]. [Mn(CO)6][AlCl4] and triphenylgermane turn out to be essential as reactive carbonyl precursors and for the reduction of GeI4. According to X-ray structure analysis based on single crystals, the title compound exhibits a novel {MnGe3} cluster unit with Mn-Ge single bonds and surprisingly short distances (236-241 pm). Although sensitive to oxygen/moisture, the carbonyl compound is stable up to a temperature of 150 °C. Mass spectrometry (MS) shows [Mn(CO)3(GeI3)2]-, [Mn(CO)3(GeI3)I]-, and [GeI3]- as decomposition fragments in the gas phase. In addition to crystal structure analysis and MS, the title compound is characterized by energy-dispersive X-ray spectroscopy (EDXS), thermogravimetry (TG), optical spectroscopy (UV-visible), infrared spectroscopy (FT-IR), and density functional theory (DFT) calculations.