Ge-Fe Carbonyl Cluster Compounds: Ionic Liquids-Based Synthesis, Structures, and Properties

Nine Ge-Fe carbonyl cluster compounds are prepared via ionic liquids-based synthesis. This includes the novel compounds [EMIm][Fe(CO)3 I(GeI3 )], [EHIm][Fe(CO)3 I(GeI3 )], [BMIm][GeI2 {Fe(CO)4 }2 (μ-I)][AlCl4 ]2 , [GeI2 {Fe(CO)4 }2 (μ-I)][Fe(AlBr4 )3 ], [BMIm]2 [(FeI2 )0.75 {Fe(CO)2 I(GeI3 )2 }2 ], and [EHIm][Fe(CO)4 (GeI2 )2 Fe(CO)3 GeI3 ] as well as the previously reported compounds (Fe(CO)4 (GeI3 )2 , FeI4 {GeI3 Fe(CO)3 }2 , and Ge12 {Fe(CO)3 }8 (μ-I)4 (EMIm: 1-ethyl-3-methylimidazolium, EHIm: 1-ethylimidazolium, BMIm: 1-butyl-3-methylimidazolium). With this series of compounds, a comparison of synthesis conditions and structural features is possible and, for instance, allows correlating the composition and structure of the respective Ge-Fe carbonyl cluster compounds with the type and acidity of the ionic liquid. With [EMIm][{GeI3 }2 Fe(CO)3 I], moreover, we can exemplarily show the thermal decomposition as a single-source precursor in the ionic liquid, resulting in bimetallic Ge-Fe nanoparticles with small size and narrow size distribution (7.0±1.4 nm).

Pseudohalogen Chemistry in Ionic Liquids with Non-innocent Cations and Anions

Within the second funding period of the SPP 1708 "Material Synthesis near Room Temperature",which started in 2017, we were able to synthesize novel anionic species utilizing Ionic Liquids (ILs) both, as reaction media and reactant. ILs, bearing the decomposable and non-innocent methyl carbonate anion [CO3 Me]- , served as starting material and enabled facile access to pseudohalide salts by reaction with Me3 Si-X (X=CN, N3 , OCN, SCN). Starting with the synthesized Room temperature Ionic Liquid (RT-IL) [nBu3 MeN][B(OMe)3 (CN)], we were able to crystallize the double salt [nBu3 MeN]2 [B(OMe)3 (CN)](CN). Furthermore, we studied the reaction of [WCC]SCN and [WCC]CN (WCC=weakly coordinating cation) with their corresponding protic acids HX (X=SCN, CN), which resulted in formation of [H(NCS)2 ]- and the temperature labile solvate anions [CN(HCN)n ]- (n=2, 3). In addition, the highly labile anionic HCN solvates were obtained from [PPN]X ([PPN]=μ-nitridobis(triphenylphosphonium), X=N3 , OCN, SCN and OCP) and HCN. Crystals of [PPN][X(HCN)3 ] (X=N3 , OCN) and [PPN][SCN(HCN)2 ] were obtained when the crystallization was carried out at low temperatures. Interestingly, reaction of [PPN]OCP with HCN was noticed, which led to the formation of [P(CN)2 ]- , crystallizing as HCN disolvate [PPN][P(CN⋅HCN)2 ]. Furthermore, we were able to isolate the novel cyanido(halido) silicate dianions of the type [SiCl0.78 (CN)5.22 ]2- and [SiF(CN)5 ]2- and the hexa-substituted [Si(CN)6 ]2- by temperature controlled halide/cyanide exchange reactions. By facile neutralization reactions with the non-innocent cation of [Et3 HN]2 [Si(CN)6 ] with MOH (M=Li, K), Li2 [Si(CN)6 ] ⋅ 2 H2 O and K2 [Si(CN)6 ] were obtained, which form three dimensional coordination polymers. From salt metathesis processes of M2 [Si(CN)6 ] with different imidazolium bromides, we were able to isolate new imidazolium salts and the ionic liquid [BMIm]2 [Si(CN)6 ]. When reacting [Mes(nBu)Im]2 [Si(CN)6 ] with an excess of the strong Lewis acid B(C6 F5 )3 , the voluminous adduct anion {Si[CN⋅B(C6 F5 )3 ]6 }2- was obtained.

Ionic-liquid-based synthesis of tellurium-rhenium carbonyls with specific reaction control

The novel tellurium rhenium carbonyls [TeI2Re(CO)5][AlCl4] (1), [BMIm][Te2I4(μ-I)2Re(CO)4] (2), {Te3I2(μ-I)3(μ3-I)}Re(CO)3 (3) and [BMIm][(Te2)3{Re(CO)3}2{Re(CO)4}3] (4) were prepared by reacting TeI4 and Re2(CO)10 in ionic liquids (ILs). [TeI2Re(CO)5][AlCl4] (1) was obtained in a mixture of [BMIm]Cl (BMIm: 1-butyl-3-methylimidazolium) and AlCl3 (ratio: 1 : 1) and contains a [TeI2Re(CO)5]+ cation. Increasing the amount of AlCl3 ([BMIm]Cl : AlCl3 = 1 : 2) results in [BMIm][Te2I4(μ-I)2Re(CO)4] (2) with the anion [Te2I4(μ-I)2Re(CO)4]-. At a [BMIm]Cl to AlCl3 ratio of 1 : 3, {Te3I2(μ-I)3(μ3-I)}Re(CO)3 (3) was realized with a Te3I3 ring and μ3-coordinating iodine. Finally, [BMIm][(Te2)3{Re(CO)3}2{Re(CO)4}3] (4) was prepared in [BMIm][OTf] (OTf: triflate) and contains the ufosan-like anion [(Te2)3{Re(CO)3}2{Re(CO)4}3]- with three Te22- and two Re(CO)3+ units that establish a distorted heterocuban-like cage. The compounds were characterized by single-crystal structure analysis, energy dispersive X-ray (EDX) analysis, thermogravimetry (TG), and infrared spectroscopy (FT-IR). The course of the reaction and the formation of the four novel tellurium-rhenium carbonyls can be directly correlated to the reaction conditions and especially to the acidity of the IL.

[Pb{Mn(CO)5}3][AlCl4]: a lead-manganese carbonyl with AlCl4-linked PbMn3 clusters

[Pb{Mn(CO)5}3][AlCl4] containing a trigonal planar PbMn3 cluster was obtained by the reaction of PbCl2 and Mn2(CO)10 in the ionic liquid [BMIm][AlCl4]. The title compound is composed of [Pb{Mn(CO)5}3]+ carbonyl cations and [AlCl4]- anions that are connected to infinite zig-zag chains. The [Pb{Mn(CO)5}3]+ cation exhibits a central PbMn3 cluster with three equal Pb-Mn single bonds, resulting in an almost equilateral triangle of three manganese atoms with a formal Pb+I in its center. Such a cluster and compound were identified for the first time. In addition to single-crystal structure analysis, the composition, structure and properties were further characterized by density functional theory (DFT) calculations, energy dispersive X-ray spectroscopy (EDXS), and Fourier-transform infrared spectroscopy (FT-IR), as well as optical spectroscopy (UV-Vis).

Ge12{Fe(CO)3}8(μ-I)4: a germanium–iron cluster with Ge4, Ge2 and Ge units

The novel germanium–iron cluster Ge₁₂{Fe(CO)₃}₈(μ-I)₄is presented, which contains a Ge₁₂Fe₈ metal core with a central Ge₄ rectangle, two Ge₂ pairs, and four single Ge atoms. The cluster was made by ionic-liquid-mediated reaction of GeI₄ and Fe₂(CO)₉. The cluster is one of the largest intermixed Ge–Fe clusters and exhibits three different partial charges on the Ge₄, Ge₂, and single Ge moieties.