Germanium Analogues Research Articles

Structural Diversity of Sn(II) Phosphine Oxide Complexes with Weakly Coordinating Anions and Comparisons with Related Ge(II) and Pb(II) Species

AbstractA series of tin(II) triflate phosphine oxide complexes has been prepared from the reaction of Sn(OTf)2 (OTf− = [O3SCF3]−) with various ratios of OPPh3, OPMe3 or dppmO2 (dppmO2 = Ph2(O)PCH2P(O)Ph2). The complexes [Sn(OPPh3)n][OTf]2 (n = 2, 3 or 4), [Sn(OPMe3)n][OTf]2 (n = 2 or 3) and [Sn(dppmO2)n][OTf]2 (n = 1 or 2) have been isolated in moderate to good yields. Selected germanium(II) and lead(II) analogues have been made for comparison, namely [Ge(OPPh3)n][OTf]2 (n = 2 or 3) and [Pb(OPR3)4][OTf]2 (R = Me, Ph). The effect of changing the weakly coordinating OTf− anion for the non‐coordinating [BArF]− anion was investigated through anion metathesis, furnishing the complexes [Sn(OPPh3)n][BArF]2 (n = 3 or 4) and [Ge(OPPh3)3][BArF]2. The isolated solids were characterised by 1H, 19F{1H}, 31P{1H} and IR spectroscopy and microanalysis. Crystal structures were obtained for all complexes except [Ge(OPPh3)2][OTf]2 and [Sn(OPPh3)3][BArF]2, allowing comparisons of the structural features of these divalent group 14 complexes down the group and as a function of coordination number, ligand sterics and electronics.

The renaissance of germanium

The great moment of fame for germanium was in December 1947. In that year the first transistor was made by a research team of Bell Laboratories. Owing to some problems with germanium, it was soon supplanted by silicon. Currently, germanium is still used in the microelectronic industry for opto-electronic and solar electric applications, but its role is very minor compared to its big brother silicon. After the rise of graphene, germanium received renewed interest because of the predicted stability of the graphene-like allotrope of germanium. Germanene, the germanium analogue of graphene, shares many properties with graphene, but there are also a few interesting differences that makes this material very appealing for device applications. In this contribution, I will give a brief historical overview of germanene, discuss the pros and cons of germanene and elaborate on its potential for future device applications.

Potassium 2-germanaphthalenide: an isolable polycyclic system of germanium-incorporated anionic benzenoid

A germanium analogue of the 2-naphthyl anion, 2-germanaphthalenide, has been isolated. While it possesses ambident character as both aromatic and germylene species, the germylene character is further emphasized as compared with germabenzenide.

Germanium Analogue of the Parent Phosphine-Borane FLP Compound.

Diimino-carbene-supported germylone dimNHCGe does not react with BPh3 and does not activate dihydrogen in the FLP mode in the combination with this borane. However, it reacts with B(C6 F5 )3 to give the zwitterionic borate dimNHCGe-(C6 F4 )BF(C6 F5 )2 . This compound can be converted into the hydroborate dimNHCGe-(C6 F4 )BH(C6 F5 )2 (8) and further into [dimNHCGe-(C6 F4 )B(C6 F5 )2 ]+ (4). Compound 4 is a Ge/B analogue of Stephan's FLP parent P/B compound (C6 H2 Me3 )2 P-C6 F4 -B(C6 F5 )2 but unlike the latter cannot split dihydrogen. Moreover, attempts to prepare a Ge/B analogue of the zwitterion (C6 H2 Me3 )2 HP-C6 F4 -BH(C6 F5 )2 by protonation of borate 8 resulted in immediate elimination of H2.

Unusual nuclear exchange within a germanium-containing aromatic ring that results in germanium atom transfer

The delivery of single atoms is highly desirable for the straightforward synthesis of complex molecules, however this approach is limited by a lack of suitable atomic transfer reagents. Here, we report a germanium atom transfer reaction employing a germanium analogue of the phenyl anion. The reaction yields a germanium-substituted benzene, along with a germanium atom which can be transferred to other chemical species. The transfer of atomic germanium is demonstrated by the formation of well-defined germanium doped molecules. Furthermore, computational studies reveal that the reaction mechanism proceeds via the first example of an aromatic-to-aromatic nuclear germanium replacement reaction on the germabenzene ring. This unusual reaction pathway was further probed by the reaction of our aromatic germanium anion with a molecular silicon species, which selectively yielded the corresponding silicon-substituted benzene derivative.

Structural and thermal properties of Eu2Ga11Sn35

Clathrates have been reported to form in a variety of different structure types; however, inorganic clathrate-I materials with a low-cation concentration have yet to be investigated. Furthermore, tin-based compositions have been much less investigated as compared to silicon or germanium analogs. We report the temperature-dependent structural and thermal properties of single-crystal Eu2Ga11Sn35 revealing the effect of structure and composition on the thermal properties of this low-cation clathrate-I material. Specifically, low-temperature heat capacity, thermal conductivity, and synchrotron single-crystal x-ray diffraction reveal a departure from Debye-like behavior, a glass-like phonon mean-free path for this crystalline material, and a relatively large Grüneisen parameter due to the dominance of low-frequency Einstein modes. Our analyses indicate thermal properties that are a direct result of the structure and composition of this clathrate-I material.

A comprehensive DFT study on organosilicon-derived fungicide flusilazole and its germanium analogue: A computational approach to Si/Ge bioisosterism

Bioisosterism, a specific molecular alteration processing, is an effective approach used in agrochemical development studies as well as in pharmaceutical sciences. Analyzing some parameters such as size, volume, charge, aqueous/lipid solubility, polarizability, degree of hybridization, intra- and intermolecular interactions, which may be caused by bioisosteric changes, by using quantum chemical methods, provides speed and different perspectives to the studies. Towards this end, this study approached the Si/Ge bioisosterism from a computational perspective by performing DFT-based calculations on flusilazole, a widely used fungicide, and its germanium analogue. The reflections of the replacement of silicon with germanium in the structure of flusilazole on the structural parameters, frontier molecular orbital energies, quantum chemical descriptors and electrostatic surface properties were examined. Additionally, FT-IR spectra of the aforementioned molecules were visualized and investigated in detail. Natural bond orbital analyzes were also performed to determine the intermolecular interactions and their corresponding stabilization energies. Besides, 1-octanol/water partition coefficients (logPow), the quantitative identifier of lipophilicity, were calculated. It was determined that both molecules could exhibit similar lipophilic character with a difference of 0.09 logarithmic units in logPow value.

Gas-Phase Preparation of 1-Germavinylidene (H2CGe; X1A1), the Isovalent Counterpart of Vinylidene (H2CC; X1A1), via Non-adiabatic Dynamics through the Elementary Reaction of Ground State Atomic Carbon (C; 3P) with Germane (GeH4; X1A1).

1-Germavinylidene (H2CGe; X1A1), the germanium analogue of vinylidene (H2CC; X1A1), was prepared via a directed gas-phase synthesis through the bimolecular reaction of ground state atomic carbon (C; 3P) with germane (GeH4; X1A1) under single-collision conditions. The reaction commences with the barrierless insertion of carbon into the Ge-H bond followed by intersystem crossing from the triplet to singlet surface and migration of atomic hydrogen to germylene (H2GeCH2), which predominantly decomposes via molecular hydrogen loss to 1-germavinylidene (H2CGe; X1A1). Therefore, the replacement of a single carbon atom in the acetylene-vinylidene system by germanium critically impacts the chemical bonding, molecular structure, and thermodynamic stability of the carbene-type structures favoring 1-germavinylidene (H2CGe) over germyne (HGeCH) by 160 kJ mol-1. Hence, the carbon-germane system represents a benchmark in the exploration of the chemistries of main group 14 elements with germanium-bearing systems showing few similarities with the isovalent carbon system.

Interaction of germanium analogue of organic isonitrile with Cu(I) imide in side-on mode.

[NHC → GeN(Ar)Cu2NAr]2, the formal adduct of germanium analogue of organic isonitrile [GeNAr] with Cu(I) imide [(Cu2NAr)2] (Ar = 2,6-iPr2C6H3) was prepared from the N-heterocyclic carbene (NHC) stabilized acyclic germylene Ge[N(H)Ar]2 by reacting with two equivalents of nBuLi and CuCl(PPh3)3. As elucidated by X-ray crystal structural characterization, the two separated [GeNAr] moieties interacted with [(Cu2NAr)2] core in the side-on mode.

2D Functionalized Germananes: Synthesis and Applications.

In the realm of 2D layered materials, the monoelemental group 14 Xene, germanene, as the germanium analog of graphene, has emerged as the next prospective candidate. Preceded by silicon, germanium is widely used in the semiconductor industry; thus, germanene is deemed compatible with existing semiconductor technologies. Germanene consists of mixed sp2 -sp3 -hybridized networks in a buckled hexagonal honeycomb structure. Chemical exfoliation of Zintl phases, such as CaGe2 , specifically the topotactical deintercalation in acidic media, removes the alkaline earth metal ions Ca2+ , giving rise to layered germanane (germanene with the Ge centers covalently saturated with terminal hydrogen atoms). Diverse variants of functionalized germananes (with covalent group(s) termination) can be obtained by varying the topotactical deintercalation precursors, elevating the game with limitless functionalization possibilities for customizable properties or new functionalities. The preparation of Zintl phases to the details of functionalized and modified germananes and their properties, and the additional exfoliation step to achieve mono- or few-layer germananes, are comprehensively covered. The progress and challenges of 2D functionalized germananes in optoelectronics, catalysis, energy conversion and storage, sensors, and biomedical areas are reviewed. This review provides insight into designing and exploring this class of atomically thin semiconductors in realizing future nanoarchitectonics.

The Insertion of EII and EIV Chlorides (E=Si, Ge) into the Si-Si Bond of Disilylene.

Reactions of silicon and germanium dichlorides L⋅ECl2 (E=Si, L=IPr; E=Ge, L=dioxane) with the phosphinoamidinato-supported disilylene ({κ2 (N,P)-NNP}Si)2 resulted in formal tetrylene insertions into the Si-Si bond. In the case of the reaction with silylene, two products were isolated. The first product ({κ2 (N,P)-NNP}Si)2 SiCl2 , is the formal product of direct SiCl2 insertion into the Si-Si bond of ({κ2 (N,P)-NNP}Si)2 and thus features two separated silylamido silylene centers. Over time, migration of the SiCl2 group to a lateral position afforded the second product, the disilylene {κ2 (Si,P)-SiCl2 NNP}Si-Si{κ2 (N,P)-NNP}. In contrast, insertion of GeCl2 resulted only in the isolation of the germanium analogue of {κ2 (Si,P)-SiCl2 NNP}Si-Si{κ2 (N,P)-NNP}, containing a Ge atom in the central position namely, compound {κ2 (Si,P)-SiCl2 NNP}Ge-Si{κ2 (N,P)-NNP}, which is a rare example of a silylene-germylene. Finally, reaction of disilylene ({κ2 (N,P)-NNP}Si)2 with SiCl4 and SiHCl3 led to the formation of the new bis(silyl)silylene, ({NNP}SiCl2 )2 Si:. All four new products from these insertion reactions have been characterized by multinuclear NMR and single-crystal X-ray diffraction studies.

Pertoldite, trigonal GeO2, the germanium analog of α-quartz: a new mineral from Radvanice, Czech Republic

Pertoldite, trigonal GeO2, the germanium analog of α-quartz: a new mineral from Radvanice, Czech Republic

A Silylene‐Stabilized Germanium Analogue of Alkynylaluminum

AbstractIn contrast to the well‐developed metal acetylides, the heavier analogues of the type REEM (E=Si, Ge, Sn, Pb; M=metals) have not been reported to date. Herein, we describe the synthesis of a silylene‐stabilized germanium analogue of alkynylaluminum (4) by the reaction of a silylene‐stabilized digermavinylidene (3) with 0.25 equiv of (AlCp*)4in THF at 80 °C. The structure of4has been unambiguously characterized by spectroscopic analysis, X‐ray diffraction analyses and DFT calculations, and features a linear AlGeGe skeleton with a Ge=Ge double bond and a polarized Ge−Al bond. Complex4shows excellent reactivity towards small molecules such as H2, CS2and TolNCO, and this allows for the construction of the structurally intriguing germylenyl aluminum complex (5) and the germacycles (6,7).

A Silylene-Stabilized Germanium Analogue of Alkynylaluminum.

In contrast to the well-developed metal acetylides, the heavier analogues of the type REEM (E=Si, Ge, Sn, Pb; M=metals) have not been reported to date. Herein, we describe the synthesis of a silylene-stabilized germanium analogue of alkynylaluminum (4) by the reaction of a silylene-stabilized digermavinylidene (3) with 0.25 equiv of (AlCp*)4 in THF at 80 °C. The structure of 4 has been unambiguously characterized by spectroscopic analysis, X-ray diffraction analyses and DFT calculations, and features a linear AlGeGe skeleton with a Ge=Ge double bond and a polarized Ge-Al bond. Complex 4 shows excellent reactivity towards small molecules such as H2 , CS2 and TolNCO, and this allows for the construction of the structurally intriguing germylenyl aluminum complex (5) and the germacycles (6, 7).

Accessing Cationic α-Silylated and α-Germylated Phosphorus Ylides.

The synthesis and full characterization of α‐silylated (α‐SiCPs; 1–7) and α‐germylated (α‐GeCPs; 11–13) phosphorus ylides bearing one chloride substituent R3PC(R1)E(Cl)R2 2 (R=Ph; R1=Me, Et, Ph; R2=Me, Et, iPr, Mes; E=Si, Ge) is presented. The molecular structures were determined by X‐ray diffraction studies. The title compounds were applied in halide abstraction studies in order to access cationic species. The reaction of Ph3PC(Me)Si(Cl)Me2 (1) with Na[B(C6F5)4] furnished the dimeric phosphonium‐like dication [Ph3PC(Me)SiMe2]2[B(C6F5)4]2 (8). The highly reactive, mesityl‐ or iPr‐substituted cationic species [Ph3PC(Me)SiMes2][B(C6F5)4] (9) and [Ph3PC(Et)SiiPr2][B(C6F5)4] (10) could be characterized by NMR spectroscopy. Carrying out the halide abstraction reaction in the sterically demanding ether iPr2O afforded the protonated α‐SiCP [Ph3PCH(Et)Si(Cl)iPr2][B(C6F5)4] (6 dec) by sodium‐mediated basic ether decomposition, whereas successfully synthesized [Ph3PC(Et)SiiPr2][B(C6F5)4] (10) readily cleaves the F−C bond in fluorobenzene. Thus, the ambiphilic character of α‐SiCPs is clearly demonstrated. The less reactive germanium analogue [Ph3PC(Me)GeMes2][B{3,5‐(CF3)2C6H3}4] (14) was obtained by treating 11 with Na[B{3,5‐(CF3)2C6H3}4] and fully characterized including by X‐ray diffraction analysis. Structural parameters indicate a strong CYlide−Ge interaction with high double bond character, and consequently the C−E (E=Si, Ge) bonds in 9, 10 and 14 were analyzed with NBO and AIM methods.

Crystal structure of a 1,1-dibutyl-1H,3H-naphtho[1,8-cd][1,2,6]oxastannaborinin-3-ol.

The title oxastannaborininol compound, [Sn(C4H9)2(C10H7BO2)], has been synthesized and crystallized. While heterocycles containing a C-O-B group are common, heterocycles containing an E-O-B unit, where E is an element of the carbon group except for carbon, are rare. In fact, while heterocycles containing Si-O-B units are occasionally reported (although without crystal structures), there are no reports for the corresponding germanium, tin or lead analogues. Herein, the first synthesis and crystal structure of a heterocycle containing an Sn-O-B unit is described. The asymmetric unit contains one mol-ecule showing a notable disorder of the tin atom and the butyl groups. They occupy two sets of positions with site-occupancy factors of 0.295 (6) and 0.705 (6).

Titanium Germylidenes

AbstractTwo novel 18‐electron titanium germylene complexes, Cp2Ti(L)=Ge[Si3(SiMetBu2)4] 3 b (L=Me3P) and 3 c (L=XylNC), were synthesized, isolated, and structurally characterized. The length of the titanium‐germanium bonds of 2.5387(3) Å and 2.5276(3) Å (in 3 b and 3 c, respectively) well match those expected for the double bond, which was further supported by the DFT study. Based on their structural characteristics, as well as their atomic charges calculations which revealed Ti(δ+)=Ge(δ−) bond polarization, both 3 b and 3 c are classified as the Schrock‐type titanium germylidenes, as the germanium analogues of the widely known titanium alkylidenes. By contrast, germylene complexes of the group 6 metals 8 a (M=Mo) and 8 b (M=W) are better described as Fischer‐type germylene complexes.

Hydride Affinities for Main-Group Hydride Reductants: Assessment of Density Functionals and Trends in Reactivities.

In the present study, we have examined hydride affinities relevant to a range of group 13 and group 14 reductants. We use the high-level W1X-G0, G4(MP2)-XK, and DSD-PBEP86 methods to obtain the RHA42 set of accurate reductant hydride affinities. Assessment of DFT methods with the RHA42 set shows that all functionals that we have examined are fairly accurate. Overall, we find ωB97X-V to be the most accurate. The MN12-SX screened-exchange functional and the nonhybrid B97-D3BJ method also perform well, and they may provide a lower-cost means for obtaining hydride affinities. The trend in the hydride affinities suggests an increased reducing power when one moves down the periodic table, e.g., with TlH3 being a stronger reductant than BH3. We also find that group 13 hydrides are stronger reductants than the group 13 analogues. In general, substitution of a hydrogen, e.g., BH2+ → BHMe+, and the formation of dimer, e.g., BH2+ → B2H5+, also lead to stronger reductants. A notable observation is the small hydride affinities for silyl cations, which are indicative of the potential of silanes as strong reducing agents. In particular, poly(methylhydrosiloxane) (PMHS) cations are associated with especially small hydride affinities owing to the presence of intramolecular oxygen atoms that can stabilize the cation center. We have further found the germanium analogues of the silanes to be more reactive, and they may further widen the scope of main-group hydride reducing agents.

Synthesis of 2D Germanane (GeH): a New, Fast, and Facile Approach

Germanane (GeH), a germanium analogue of graphane, has recently attracted considerable interest because its remarkable combination of properties makes it an extremely suitable candidate to be used as 2D material for field effect devices, photovoltaics, and photocatalysis. Up to now, the synthesis of GeH has been conducted by substituting Ca by H in a β‐CaGe2 layered Zintl phase through topochemical deintercalation in aqueous HCl. This reaction is generally slow and takes place over 6 to 14 days. The new and facile protocol presented here allows to synthesize GeH at room temperature in a significantly shorter time (a few minutes), which renders this method highly attractive for technological applications. The GeH produced with this method is highly pure and has a band gap (E g) close to 1.4 eV, a lower value than that reported for germanane synthesized using HCl, which is promising for incorporation of GeH in solar cells.

Synthesis of 2D Germanane (GeH): a New, Fast, and Facile Approach

AbstractGermanane (GeH), a germanium analogue of graphane, has recently attracted considerable interest because its remarkable combination of properties makes it an extremely suitable candidate to be used as 2D material for field effect devices, photovoltaics, and photocatalysis. Up to now, the synthesis of GeH has been conducted by substituting Ca by H in a β‐CaGe2 layered Zintl phase through topochemical deintercalation in aqueous HCl. This reaction is generally slow and takes place over 6 to 14 days. The new and facile protocol presented here allows to synthesize GeH at room temperature in a significantly shorter time (a few minutes), which renders this method highly attractive for technological applications. The GeH produced with this method is highly pure and has a band gap (Eg) close to 1.4 eV, a lower value than that reported for germanane synthesized using HCl, which is promising for incorporation of GeH in solar cells.