Synthesis and Characterization of Germanium Coordination Compounds for Production of Germanium Nanomaterials

Abstract

A series of novel germanium(II) precursors was synthesized to initiate an investigation between the precursors’ structures and the morphologies of the resulting nanoparticles. The precursors were synthesized from the reaction of Ge[N(SiMe3)2]2 or [Ge(OBut)2]2 and the appropriate ligand: N,N’-dibenzylethylenediamine (H2-DBED), tert-butanol (H-OBut), 2,6-di-methyl phenol (H-DMP), 2,6-di-phenyl phenol (H-DPP), tert-butyldimethylsilanol (H-DMBS), triphenylsilanol (H-TPS), triphenylsilanethiol (H-TPST), and benzenethiol (H-PS). The products were identified as: [Ge(μc-DBED)]2 (1, μc= bridging chelating), [Ge(μ-DMP)(DMP)]2 (2), Ge(DPP)2 (3), [Ge(μ-OBut)(DMBS)]2, (4), [Ge(μ-DMBS)(DMBS)]2 (5), Ge(TPS)3(H) (6), [Ge(μ-TPST)(TPST)]2 (7), and Ge(PS)4 (8). The Ge(II) metal centers were found to adopt a pyramidal geometry for 1, 2, 4, 5, 7, a bent arrangement for 3, and a tetrahedral coordination for the Ge(IV) species 6 and 8. Using a simple solution precipitation methodology, Ge(0) nanomaterials were isolated as dots and wires for the majority of precursors. Compound 7 led to the isolation of amorphous GexSy. The nanomaterials isolated were characterized by TEM, EDS, and powder XRD. A correlation between the precursor’s arrangement and final observed nanomorphology was proffered as part of the ‘precursor structure affect’ phenomenon.

From rational design of organometallic precursors to optimized synthesis of core/shell Ge/GeO2nanoparticles

“…This seems to indicate an extension of the electronic delocalization involving one phenyl ring and the nitrogen atom leading to a positive charge on the nitrogen atom and by consequence to a less strong bond between the germanium and the nitrogen atoms. The Ge-O distance (1.845 Å) in 1 is quite close to that observed for alkoxygermylene (1.844 Å), 12,17 for hydroxygermylene (1.840 Å) 17 and is characteristic of a covalent Ge-O bond (1.82 Å). 16 In order to gain insight into the suitability of these precursors for nanomaterial production, thermal gravimetric analyses (TGA) were performed for each compound (Fig.…”

“…In both cases, the initiation of the organic decomposition occurred around 200°C that is in the range of the decomposition temperature observed for germanium(II) precursors. 12 …”

“…In the case of Ge[N(SiMe 3 ) 2 ] 2 , the too high lability of the Ge-N bonds was invoked to explain the low control of the NP shape. 12 In addition, in contrast to expectations, high working temperatures (>285°C) are still required in all the cases. This brief overview of the literature shows that the reported synthesis of Ge NPs requires drastic experimental conditions.…”

Size and emission color tuning in the solution phase synthesis of highly luminescent germanium nanocrystals

“…A number of different synthetic approaches have been reported, including the metathesis reaction of GeCl 4 with Zintl salts, [8][9][10][11][12] reduction of NaGe by ammonium bromide 13 and high temperature decomposition of organogermane precursors. [14][15][16][17][18][19][20][21] Other methods include thermal co-reduction of Ge(II) and amido based precursors, 6,22,23 aqueous phase reduction of GeO 2 powders by NaBH 4 , 24 and other high temperature chemical reduction methods. [25][26][27][28][29][30][31] However, disadvantages associated with these methods include synthetically involved precursor synthesis, long reaction times, high temperatures and pressures, and extensive post synthetic purification procedures.…”

Porous Ge@C materials via twin polymerization of germanium(ii) salicyl alcoholates for Li-ion batteries

“…The germanium oxygen bond lengths [O Aryl -Ge bonds: 1.8408(19)Å-1.848(2)Å, O Alkyl -Ge bonds: 1.939(2)Å-1.988(2)Å] are in the typical ranges reported for Ge-O bonds in compounds with a threefold pyramidal coordination of low valent germanium. [69][70][71] The values reported for the germanium oxygen bonds for (4) 3 [O Aryl -Ge bonds: 1.829(2)Å-1.890(2)Å, O Alkyl -Ge bonds: 1.945(2) A-2.044(2)Å] resemble those in (1) 3 but are slightly longer [with the exception of Ge3-O5: 1.8447(19)Å for (1) 3 and 1.829(3)Å for (4) 3 ] due to sterically more demanding substituents at the aromatic moieties in (4) 3 . 68 The shorter Ge1-O2 [1.986(2)Å], Ge3-O6 [1.951(2)Å] and Ge2-O4 [1.939(2)Å] bonds in comparison to the Ge1-O4 [1.975(2)Å], Ge3-O2 [1.988(2)Å] and Ge2-O6 [1.988(2)Å] bond lengths, respectively, indicate secondary bonding of O4 / Ge1, O6 / Ge2 and O2 / Ge3 stabilizing the low valent species.…”