Cationic Germanium Research Articles

Crystalline Germanium‐Dipyrromethene Radicals: from a Delocalized Neutral to a Localized Cation

Comprehensive SummaryBoth dipyrromethene complexes and radicals of heavier main group elements have been of high interest. However, cationic germanium radicals and dipyrromethene‐based radicals of heavier main group elements are still escaped to be isolated. Herein, we report the isolation and full characterization of a neutral Ge(I)‐masked dipyrromethene‐based radical 3 and the first cationic Ge(III)‐centered radical 5·+ as stable crystalline solids. 3 behaves as a germanium(I) radical in its reaction with diphenyl disulfide to form the Ge—S bond, although X‐ray crystallographic, EPR spectroscopic, computational studies revealed that the unpaired electron of 3 is mainly delocalized over the C9N2Ge backbone and the allylic radical character is also significant in 3. In contrast to 3, the spin density of 5·+ is mainly localized at the Ge center with minor contribution from the dipyrromethene ligand. Moreover, reduction of 5·+ with potassium graphite quantitatively regenerates 5, illustrating a reversible one‐electron redox pair.

Research on a novel chalcohalide glass and its physical optics properties

Two series of novel chalcohalide glasses varying on different molar percentages of cations and anions were prepared successfully. We experimentally investigated the physical optics properties of the chalcohalide hybrid glass (Ge-As-S-Se-I) system. The results show that the short-wavelength cut-off edge (λvis), linear refractive index (n0), and zero-dispersion-wavelength (ZDW) regularly decrease with the increase of anionic iodine mole percentage. And the addition of cationic germanium enhances the glass transition temperature (Tg), softening temperature (Tp) and crystallization temperature (Tx). Besides, a mono-index optical fiber was drawn successfully using the high temperature polymer as the protective layer, with a minimum loss of 1.91 dB/m at 2.6 μm. Supercontinuum (SC) covering 1.01 ∼ 8.32 μm was generated by pumping the 10-cm-long fiber at a femtosecond laser of 3.78 μm (∼150 fs, 1 kHz, 20 mW). This novel infrared (IR) glass shows great potential in many applications, such as defense military, spectroscopy, long-distanceremote sensing.

A systematic investigation of structural growth patterns and electronic properties of [LuGen]+/0 and [Gen+1]+/0 (n = 1–17) nanoalloy clusters

The geometries, stabilities, evolutions, and electronic properties of lutetium-doped germanium nanoalloy clusters LuGen (n = 1–17) in the neutral and cationic state are studied and compared with Gen+1 clusters by using unbiased global search method combined with a hybrid density functional approach. The results reveal that neutral and cationic structural growth patterns prefer Lu-substituted Gen+1 for n = 1–8, Lu-linked configuration for n = 9–14 (for cation n = 9–15) in which Lu atom links two Ge subclusters, and Lu-encapsulated Ge cage-like motif for n = 15–17 (for cation n = 16–17). A binding energy analysis reveals that Lu-encapsulated motifs enhance the nanocluster stability. Lu-doped neutral and cationic germanium clusters can decrease their ionization potential. Natural population analysis shows that Lu in Lu-substituted and Lu-linked configurations acts as electron donor, but acts as electron acceptor in Lu-encapsulated structures. HOMO-LUMO energy gap analysis discloses that Lu-doped Ge clusters can lessen their chemical stability excluding LuGe12 and LuGe17. Thorough analysis of stability, chemical bonding, density of states, iso-chemical shielding surface and UV-Vis spectra revealed that [LuGe17]+ is magic nanoalloy cluster, and has an ideal chemical and thermal stability, making it the most preferable building block for optoelectronic materials. Additionally, Infrared and Raman spectra of [LuGe17]+ are also reported. The accordance between theoretical and experimental values for binding energies of Ge2–8 and ionization potentials of Ge2–16,18 clusters suggest that the calculations and analysis of results in this study are successful.

Neutral and cationic germanium(IV) fluoride complexes with phosphine coordination - synthesis, spectroscopy and structures.

The neutral complexes trans-[GeF4(PiPr3)2] and [GeF4(κ2-L)] (L = CH3C(CH2PPh2)3 or P(CH2CH2PPh2)3) are obtained from [GeF4(MeCN)2] and the ligand in CH2Cl2. Treatment of [GeF4(PMe3)2] with n equivalents of TMSOTf (Me3SiO3SCF3) leads to formation of the series [GeF4-n(PMe3)2(OTf)n] (n = 1, 2, 3), each of which contains six-coordinate Ge(IV) with trans PMe3 ligands and X-ray structural data confirm that the OTf groups interact with Ge(IV) to varying degrees. Unexpectedly, [GeF3(PMe3)2(OTf)] undergoes reductive defluorination in solution, forming the Ge(II) complex, [Ge(PMe3)3][OTf]2 (and [FPMe3]+). The bulkier PiPr3 leads to formation of the ionic [GeF3(iPr3P)2][OTf], containing a [GeF3(iPr3P)2]+ cation. [GeF4{o-C6H4(PMe2)2}], containing the cis-chelating diphosphine, also reacts with n equivalents of TMSOTf to generate [GeF4-n{o-C6H4(PMe2)2}(OTf)n] (n = 1, 2, 3). As for the PMe3 system, the trifluoride, [GeF3{o-C6H4(PMe2)2}(OTf)], is unstable to reductive defluorination in solution, producing the pyramidal Ge(II) complex [Ge{(o-C6H4(PMe2)2}(OTf)][OTf], whose crystal structure has been determined. The [GeF3{Ph2P(CH2)2PPh2}(OTf)] and [GeF2{Ph2P(CH2)2PPh2}(OTf)2], obtained similarly from the parent tetrafluoride complex, are poorly soluble, however their structures were confirmed crystallographically. The complexes in this work have been characterised via variable temperature 1H, 19F{1H} and 31P{1H} NMR studies in solution, IR spectroscopy and microanalysis and through single crystal X-ray analysis of representative examples across each series. Trends in the NMR and structural parameters are also discussed.

C–H and C–N Bond Activation of Tertiary Amines by Cationic Germanium(IV) Corrole

C–H and C–N bonds in tertiary amines were activated by the germanium(IV) corrole cation [(TPFC)Ge]+ (TPFC = 5,10,15-tris(pentafluorophenyl)corrole) at room temperature. Cleavage of C–H bonds with a...

Oxidation of a germanium(ii) dication to access cationic germanium(iv) fluorides.

The synthesis and characterization of the tris(1-ethyl-benzoimidazol-2-ylmethyl)amine (BIMEt3 = L) complex of Ge(ii)2+ is described. Oxidation of [LGe]2+ with Selectfluor gives [LGeF2]2+, in a process that is envisaged to involve a tricationic complex [LGeF]3+ as an intermediate, which has been isolated by fluoride ion abstraction from [LGeF2]2+.

Synthesis, Electronic Structure, and Reactivity Studies of a 4-Coordinate Square Planar Germanium(IV) Cation.

A tetra-coordinate, square planar germanium(IV) cation [(TPFC)Ge](+) (TPFC = tris(pentafluorophenyl)corrole) was synthesized quantitatively by the reaction of (TPFC)Ge-H with [Ph3C](+)[B(C6F5)4](¯). The highly reactive [(TPFC)Ge](+) cation reacted with benzene to form phenyl complex (TPFC)Ge-C6H5 through an electrophilic pathway. The key intermediate, a σ-type germylium-benzene adduct, [(TPFC)Ge(η(1)-C6H6)](+), was isolated and characterized by single-crystal X-ray diffraction. Deprotonation of [(TPFC)Ge(η(1)-C6H6)](+) cation led to the formation of (TPFC)Ge-C6H5. [(TPFC)Ge](+) also reacted with ethylene and cyclopropane in benzene at room temperature to form (TPFC)Ge-CH2CH2C6H5 and (TPFC)Ge-CH2CH2CH2C6H5, respectively. The observed electrophilic reactivity is ascribed to the highly exposed cationic germanium center with novel frontier orbitals comprising two vacant sp-hybridized orbitals that are not conjugated to π-system. The three electron-withdrawing pentafluorophenyl groups on the corrole ligand also enhance the electrophilicity of the cationic germanium corrole.

Facile, High-Yield Functionalization of Germanium and Tin by Oxidative Insertion of Tetrelenes into the E–H Bonds of Inorganic Acids (E = C, N, O, F): Arene Elimination versus Oxidative Addition and Formation of a Germanium Cation–Water Complex

Reaction of the diarylgermylene Ge(ArMe6)2 [ArMe6 = C6H3-2,6-(C6H2-2,4,6-(CH3)3)2] with various inorganic acids (HCN, HN3, and HBF4) led to the facile oxidation of the germanium atom to yield the corresponding Ge(IV) products (ArMe6)2Ge(H)X (X = CN (1), N3 (2), F (3)). The cationic germanium–water complex [(ArMe6)2GeH(OH2)][SO3CF3] (4) was prepared by treating Ge(ArMe6)2 with triflic acid in the presence of trace amounts of moisture. The reactions provide an efficient method of installing a variety of functional groups at a germanium atom and can be used in the preparation of germanium complexes that are analogous to lighter carbon species. The tin species Sn(ArMe6)2 was also oxidized to the Sn(IV) analogue of 3. In all reactions, no evidence of arene elimination was observed, which was in contrast to the reaction of the stannylene (or bulkier germylenes) with hydrogen or ammonia, which yielded H(ArMe6), [(ArMe6)Sn(μ-H)]2, and [(ArMe6)Sn(μ-NH2)]2.

A Neutral Gallium(I) N-Heterocyclic Carbene Analogue: Synthesis, Characterization and Theoretical Analysis

The six-membered N-heterocyclic gallium(I) compound [:Ga(ButNacnac)] (ButNacnac– = [{N(Dip)C(But)}2CH]–, Dip =2,6-diisopropylphenyl) has been synthesized, crystallographically characterized, and its electronic properties analyzed using density functional theory. For purposes of comparison, the isoelectronic cationic germanium(II) complex, [:Ge(ButNacnac)][Al{OC(CF3)3}4], has been prepared and structurally authenticated.

Biological Activity of Some Novel Cationic Germanium and Titanium Metal Based Surfactants

Abstract Two new derivatives (A) and (B) of cationic germanium metal based surfactants have been synthesized. Their formulas are: [GeCl2(R)4]2+FeCl4 2− and [GeCl2(R\)4]2+SnCl4 2−·2H2O where R = hexamine and R\ = isothiouronium. A third derivative (C) of cationic titanium metal based surfactant was also synthesized and its formula is: [TiCl2(R\\)2]2+CoCl4 2−·6H2O where R\\ = triphenylphosphine. The presence of complex anions with metals was confirmed by inductive coupled plasma spectroscopy (ICP), IR spectrum and elemental analysis. Surface properties of the prepared surfactants, surface tension and critical micelle concentration were evaluated. Cytotoxic activities of these three metallo-surfactants were tested on human cell lines: leukemia lymphoblastic NALM-6 cells, promyelocytic HL-60 cells and breast adenocarcinoma MCF-7 cells. The obtained data revealed that the compound A did not exert cytotoxicity toward normal lymphocytes and was also inactive against all tumor cell lines tested. However, compounds B and C displayed high cytotoxicity in tumor cells and low toxicity in human normal lymphocytes, with concurrent high genotoxicity in all kinds of cells. All of these synthesized metallo-surfactants (A, B and C) induced oxidative DNA damage as detected by alkaline comet assay. Therefore, novel cationic germanium and titanium metal based surfactants (B and C) may be considered for use as anticancer drugs but further studies should be performed.

Cationic germanium fluorides: 2. An experimental and theoretical investigation on the reaction between GeF + and H 2O [1

The reaction between singlet ground state GeF + ( 1Σ +) and H 2O, with formation of Ge–OH + and HF, was investigated by ion trap mass spectrometry (ITMS) and ab initio calculations at the MP2 and CCSD(T) level of theory. The process involves the initial formation of the addition product FGe +–OH 2 ( 1), its interconversion into HOGe +–FH ( 2), and the eventual barrier-free dissociation into Ge–OH + and HF. The activation barrier of the 1 → 2 isomerization is comparable with the exothermicity (exoergicity) of the formation of 1, and this explains the relatively low efficiency of the process, experimentally evaluated as 0.14 from the ratio of the absolute rate constant, 3.2 × 10 −10 cm 3 molecule −1 s −1, and the collisional rate constant. The mechanism of the reaction between GeF + and H 2O is strictly analogue to that of the reaction between SiF + and H 2O, investigated so far by selected-ion flow tube (SIFT) mass spectrometry and ab initio calculations. From a general point of view, the conceivable occurrence of additional similarities between the still essentially unexplored reactivity of GeF n + ( n = 1–3) and the rich and variegated chemistry of SiF n + suggests novel attractive opportunities in the gas-phase positive ion chemistry of germanium.

Cationic Germanium Fluorides: A Theoretical Investigation on the Structure, Stability, and Thermochemistry of GeFn/GeFn+ (n = 1−3)

The structure, harmonic frequencies, enthalpies of formation, and dissociation energies of the GeF(n)(+) cations (n = 1-3) and of their neutral counterparts GeF(n) have been investigated at the MP2 and CCSD(T) levels of theory and discussed in connection with previous experimental and theoretical data. The CCSD(T,full)/cc-pVTZ-optimized geometries and MP2(full)/6-311G(d) harmonic frequencies are 1.744 A and 668.0 cm(-1) for GeF((2)Pi), 1.670 A and 798.6 cm(-1) for GeF(+)((1)Sigma(+)), 1.731 A/97.4 degrees and 267.0 (a(1))/673.1 (b(2))/690.6 (a(1)) cm(-1) for GeF(2)(C(2)(v),(1)A(1)), 1.666 A/116.9 degrees and 202.3 (a(1))/769.6 (a(1))/834.6 (b(2)) cm(-1) for GeF(2)(+)(C(2)(v),(2)A(1)), 1.706 A/112.2 degrees and 214.4 (e)/273.1 (a(1))/699.6 (a(1))/734.1 (e) cm(-1) for GeF(3)(C(3)(v),(2)A(1)), and 1.644 A and 211.4 (e')/229.9 (a(2)' ')/757.4 (a(1)')/879.3 (e') cm(-1) for GeF(3)(+)(D(3)(h),(1)A(1)). These calculated values are in excellent agreement with the experimental data reported for GeF, GeF(+), and GeF(2), and should be therefore of good predictive value for the still unexplored GeF(2)(+), GeF(3), and GeF(3)(+). The comparison of the CCSD(T,full)/cc-pVTZ enthalpies of formation at 298.15 K, -11.6 (GeF), -125.9 (GeF(2)), -180.4 (GeF(3)), 158.4 (GeF(+)), 134.1 (GeF(2)(+)), and 44.8 (GeF(3)(+)) kcal mol(-1), with the available experimental data, especially for the cations, shows discrepancies which suggest the need for novel and more refined measurements. On the other hand, the computed adiabatic ionization potentials of GeF, 7.3 eV, GeF(2), 11.2 eV, and GeF(3), 9.7 eV, are in good agreement with the available experimental estimates.

In Search of Cationic Germanium(II)−Transition Metal Complexes L2Ge+W(CO)5 and L2Ge+W(CO)4Ge+L2

New germanium(II)−tungsten complexes [L2(X)Ge]nW(CO)6-n (L2 = NPhC(Me)CHC(Me)NPh, n = 1, X = OTf (2); n = 2, X = Cl (13)) have been synthesized and characterized by X-ray crystallography. In compound 2 the triflate was found to be very weakly coordinating to the germanium in the solid state, and this result is confirmed by DFT calculations. All the spectroscopic data are consistent with the L2(X)Ge ligands being good σ-donors and poor π-acceptors in these complexes, similar to the phosphine ligands in homologous R3P complexes. Starting from the chlorogermanium(II)−tungsten complexes (L2(Cl)Ge)nW(CO)6-n (n = 1 (1), n = 2 (13)), metathesis reactions with halide or weakly coordinating anions A- (A- = TfO-, BPh4-, PF6-) have been investigated as a general approach to obtain the cationic germanium species [L2Ge+]nW(CO)6-n. In the case of A- = TfO-, spontaneous dissociation of the anion leading to an equilibrium between a neutral and a cationic tetracoordinated germanium species is observed in coordinating solvents. Treatment of L2(X)Ge with MX3 (M = Ga, X = Cl; M = In, X = I) afforded the neutral complexes L2MX2 (M = Ga (7) and In (8)) by ligand transfer reactions. The crystal structure of 8 was determined by X-ray structure analysis.

Three‐coordinate divalent Group 14 element derivatives and related compounds

AbstractThis review describes recent work on the synthesis, spectroscopic analysis, structures and investigation of chemical behaviours of new subvalent germanium and tin compounds supported by the β‐diketiminato ligand L2 (L2 = NPhC(Me)CHC(Me)NPh), namely the divalent species L2(X)M, the germane and stannane chalcogenones L2(X)MY, the heavier Group 14 element transition‐metal complexes L2(X)MM′(CO)n and the cationic germanium–transition‐metal complexes [L2Ge+M′(CO)n]. Copyright © 2005 John Wiley & Sons, Ltd.

The Cation Cluster of Heavier Group 14 Elements: A Free Germyl Cation with Trishomoaromaticity

The heavier group 14 element cation cluster compound, [(tBu3Si)6Ge10I]+.TTFPB- (3+. TTFPB-; TTFPB- = tetrakis(2,3,5,6-tetrafluorophenyl)borate), was unexpectedly obtained by thermolysis of in situ prepared iodocyclotrigermene, (tBu3Si)3Ge3I, in toluene in the presence of KI and K+.TTFPB-. The molecular structure of 3+.TTFPB- has been unambiguously determined by X-ray crystallography, showing that 3+ is a free germyl cation. The three "naked" cationic germanium atoms in the framework constitute a three-center two-electron (3c-2e) bond with a trishomocyclotrigermenylium character, which is well-supported by a theoretical calculation on the model compound Ge10H7+.

Investigation of silver salt metathesis: preparation of cationic germanium(II) and Tin(II) complexes, and silver adducts containing unsupported silver-germanium and silver-tin bonds.

Syntheses of halide derivatives of germanium(II) and tin(II) aminotroponiminate (ATI) complexes and their silver salt metathesis reactions have been investigated. The treatment of GeCl(2) x (1,4-dioxane), SnCl(2), or SnI(2) with [(n-Pr)(2)ATI]Li in a 1:1 molar ratio affords the corresponding germanium(II) or tin(II) halide complex [(n-Pr)(2)ATI]MX (where [(n-Pr)(2)ATI](-) = N-(n-propyl)-2-(n-propylamino)troponiminate; M = Ge or Sn; X = Cl or I). As usually expected, [(n-Pr)(2)ATI]GeCl and [(n-Pr)(2)ATI]SnCl undergo rapid metathesis with CF(3)SO(3)Ag, leading to trifluoromethanesulfonate salts, [[(n-Pr)(2)ATI]Ge][SO(3)CF(3)] and [[(n-Pr)(2)ATI]Sn][SO(3)CF(3)], and silver chloride. However, when the silver source [HB(3,5-(CF(3))(2)Pz)(3)]Ag(eta(2)-toluene) is used, rather than undergoing metathesis, very stable 1:1 adducts [HB(3,5-(CF(3))(2)Pz)(3)]Ag<--Ge(Cl)[(n-Pr)(2)ATI] and [HB(3,5-(CF(3))(2)Pz)(3)]Ag<--Sn(Cl)[(n-Pr)(2)ATI] are formed (where [HB(3,5-(CF(3))(2)Pz)(3)](-) = hydrotris(3,5-bis(trifluoromethyl)pyrazolyl)borate). The use of the iodide derivative [(n-Pr)(2)ATI]SnI did not change the outcome either. All new compounds have been characterized by multinuclear NMR spectroscopy and X-ray crystallography. The Ag-Ge and Ag-Sn bond distances of [HB(3,5-(CF(3))(2)Pz)(3)]Ag<-- Ge(Cl)[(n-Pr)(2)ATI], [HB(3,5-(CF(3))(2)Pz)(3)]Ag<--Sn(Cl)[(n-Pr)(2)ATI], and [HB(3,5-(CF(3))(2)Pz)(3)]Ag<--Sn(I)[(n-Pr)(2)ATI] are 2.4142(6), 2.5863(6), and 2.5880(10) A, respectively. A convenient route to [(n-Pr)(2)ATI]H is also reported.

Germanium-Containing Heterobicyclic 10-π-Electron Ring Systems. Synthesis and Characterization of Neutral and Cationic Germanium(II) Derivatives of Aminotroponiminates

The neutral and cationic aminotroponiminate derivatives of germanium(II) have been investigated. The treatment of GeCl2·(1,4-dioxane) with [(i-Pr)2ATI]Li or [(Me)2ATI]Li in a 1:1 molar ratio gave the corresponding monochloro germanium(II) complex. Substitution of the chloride ion of [(i-Pr)2ATI]GeCl with weakly coordinating anions [CF3SO3]- and [(η5-C5H5)ZrCl2(μ-Cl)3ZrCl2(η5-C5H5)]- led to cationic germanium(II) species containing {[(i-Pr)2ATI]Ge}+ ion. Although NMR data of the cationic species show notable differences relative to their neutral analog, the solid state data show only minor changes in the C7N2Ge moiety. The Ge−N bond distances of the cations are not indicative of significant Ge−N π-bonding. These compounds feature some of the smallest N−Ge−N angles known for Ge(II) compounds. Attempted synthesis of the tetraphenylborate salt of {[(Me)2ATI]Ge}+ led to a phenyl group transfer product [(Me)2ATI]GePh·BPh3 with a Ge(II)−B bond. Details of the 1H, 13C NMR spectroscopy and X-ray crystal structures...

Synthesis and Structure of a Bridging Germylidyne Complex: A Stable Germyl Cation

A three-coordinate, cationic germanium center is the unusual feature of this dimeric tungsten complex 1 generated by the thermolysis of [Cp2W(SiMe3)(GeMe2OTf)]. Delocalization of the charge onto only one of the tungsten centers is suggested by structural and orbital overlap considerations.