Stephan Schulz

Synthesis and characterization of organogallium-antimony compounds

Abstract The simple Lewis acid–base adduct Me3Ga←Sb(SiMe3)3 (1) was prepared by the reaction of Me3Ga and Sb(SiMe3)3. Dehalosilylation reaction between Me2GaCl and Sb(SiMe3)3 in 1:1 mol ratio yields the trimeric [Me2GaSb(SiMe3)2]3 (2). 1 and 2 were fully characterized by mass and NMR spectroscopy. In addition, the solid state structure of compound 2 was determined by single crystal X-ray diffraction.

Group 13/15 Organometallic Compounds—Synthesis, Structure, Reactivity and Potential Applications

Publisher Summary This chapter discusses the synthesis, structure, reactivity, and potential applications of group 13/15 organometallic compounds. Binary group 13/15 materials, typically referred to as “III–V materials”, are semiconducting materials with several applications in opto- and micro-electronic devices. Usually, thin films of such materials are needed for the desired applications. The metal organic chemical vapor deposition (MOCVD) process is the most advantageous industrial process for the synthesis of thin films of such materials. It makes use of metalorganic precursors such as group-13 trialkyls. The chapter focuses on materials containing the heavier group-15 elements, such as Sb and Bi. Their synthesis required the development of an alternative synthetic pathway such as dehydrosilylation or distibine cleavage reaction. However, in particular, Bi-containing compounds are still very rare and their synthesis is still a challenge for preparative chemists working in this field of main-group element chemistry.

A General Synthetic Pathway to Lewis Base-Stabilized, MonomericGroup 13/15 Compounds

Reactions of an equimolar amount of 4-(dimethylamino)pyridine (dmap) with several Al−E heterocycles [R2AlE(SiMe3)2]x (E = P, As; R = Me, x = 3; R = Et, x = 2) and Ga−Sb heterocycles [R2GaSb(SiMe3)2]x (R = Me, x = 3; R = Et, x = 2) in hexane offers a general pathway for the formation of monomeric, Lewis base-stabilized compounds of the type dmap−(R2)ME(SiMe3)2 (M = Al, R = Me, E = P 1, As 2; R = Et, E = As 3; M = Ga, E = Sb, R = Me 4, Et 5). Compounds 1, 2, 3 and 5 have been characterized by single-crystal X-ray diffraction.

Synthesis, X‐ray Crystal Structure, and Stability of Novel Trialkylalane−Triorganylbismuthane Adducts

Reactions of trialkylalanes AlR3 (R = Me, Et, tBu) and triorganylbismuthanes BiR′3 (R′ = iPr, SiMe3) were performed and the products investigated both in solution and in the solid state. Et3Al−Bi(SiMe3)3 (2), tBu3Al−Bi(SiMe3)3 (3), and tBu3Al−Bi(iPr)3 (6) are stable Lewis acid−base adducts in pure form while only 3 and 6 are adducts in solution. Their dissociation enthalpies, as determined by temperature-dependent NMR spectroscopy, were estimated to 6.3 (3) and 6.9 kcal/mol (6). In contrast, Me3Al−Bi(SiMe3)3 (1), Et3Al−Bi(SiMe3)3 (2), Me3Al−Bi(iPr)3 (4), and Et3Al−Bi(iPr)3 (5) are fully dissociated in solution. Compounds 1−6 were characterized by multinuclear NMR spectroscopy (1H, 13C), mass spectrometry, and elemental analysis. In addition, the crystal structures of 2 and 6 were determined by single-crystal X-ray diffraction. Compounds 2 and 6 are the first structurally characterized alane−triorganylbismuthane Lewis acid−base adducts.

First structural characterization of completely alkyl-substituted Al–Sb Lewis acid–base adducts

Abstract Several Lewis acid–base adducts R3Al←SbR′3 (R′=Et, R=Me (1), Et (2), t-Bu (3); R′=n-Pr, R=Me (4), Et (5), t-Bu (6); R′=i-Pr, R=Me (7), Et (8), t-Bu (9); R′=sec-Bu, R=Me (10), Et (11), t-Bu (12); R′=t-Bu, R=Me (13), Et (14), t-Bu (15)) were obtained by reaction of aluminum trialkyls R3Al and the corresponding antimony trialkyls R′3Sb. For the first time, solid state structures of all-alkyl substituted Al–Sb adducts (3, 9, 13, 14) were determined by single crystal X-ray analysis.

Growth of GaSb whiskers by thermal decomposition of a single source precursor

Thermal decomposition reactions of the Lewis acid–base adducts t-Bu3Ga–Sb(t-Bu)31 and t-Bu3Ga–Sb(i-Pr)32 were investigated at different temperatures. Both adducts lead to the formation of crystalline GaSb particles in the temperature range of 275–450 °C, proving their potential to serve as single source precursors for the preparation of GaSb. In contrast to 1, 2 tends to form crystalline, highly-oriented GaSb whiskers under the pyrolysis conditions. Detailed temperature-dependent studies clearly reveal the strong influence of the decomposition conditions on the whisker growth. While at temperatures between 275 and 375 °C single GaSb needles preferably were formed, higher temperatures (400–450 °C) lead to the formation of crystalline GaSb dendrites. As-prepared carbon-free, cubic GaSb whiskers were characterized in detail by SEM, TEM, electron diffraction, EDX and EEL spectroscopy.

First approach to an AlSb layer from the single-source precursors [Et2AlSb(SiMe3)2]2 and [iBu2AlSb(SiMe3)2]2

AlSb films have been grown on Si(100) and polycrystalline Al2O3 by high-vacuum metal-organic chemical vapor deposition (HV-MOCVD) in the temperature range 325–550 °C, using the new single-source precursors [Et2AlSb(SiMe3)2]2 (1) and [iBu2AlSb(SiMe3)2]2 (2) without any carrier gas. The best condition for a high quality AlSb film depends on the ligands of the precursor. The AlSb film is deposited at a temperature about 50 °C lower when precursor 1 is used instead of 2. The films are consistent with the 1:1 stoichiometry in the optimized temperature range of 375–425 °C for 1 and 425–475 °C for 2, whereas at other temperatures the films are contaminated with Si. The deposition rate is mainly kinetics limited and ranges from 5 to 9 μm/h. X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), energy dispersive X-ray spectrometry (EDS), and wavelength dispersive spectrometry (WDS) were used to characterize the films.

Synthesis, Structure and Reactivity of Group 13/15 Compounds Containing the Heavier Elements of Group 15, Sb and Bi

Triorganostibines and -bismuthines ER′3, as well as tetraorganodistibines and -dibismuthines E2R′4 (E = Sb, Bi) react with trialkylalanes, -gallanes and -indanes R3M (M = Al, Ga, In) under formation of simple Lewis acid-base adducts of the type R3M—ER3′ and bisadducts of the type [R3M]2[E2R′4]. Their structures and stabilities were investigated by single crystal X-ray diffraction, NMR spectroscopy and theoretical calculations. In addition, general pathways for the synthesis of heterocycles [R2MSbR2′]x will be presented. Stibinogallanes and -indanes can generally be prepared by dehalosilylation reactions, while stibinoalanes are formed by dehydrosilylation reactions. This particular pathway is also applicable for the synthesis of [Me2AlBi(Tms)2]3. In addition, MSb heterocycles (M = Al, Ga, In) can be synthesized by reaction of tetraorganodistibines and trialkylalanes, -gallanes and -indanes. Monomeric compounds R2MER′2 and RMER′ (M = Al, Ga; E = Sb, Bi) have not been reported to date, but Lewis base-stabilized monomers of the type base—M(R2)ER′2 (M = Al, Ga; E = P, As, Sb, Bi) are formed by reaction of the corresponding heterocycle with 4-(dimethylamino)pyridine (dmap). So prepared monomers react with transition metal complexes to give bimetallic complexes of the type base—M(R2)ER′2—M(CO)n.

Fabrication and investigation of nanocomposites of conducting polymers and GaSb nanocrystals

Nanocomposites consisting of GaSb nanocrystals in conducting polymer matrices were fabricated and investigated. Optical absorption and electrical properties of the samples were analyzed. Electroluminescence with a spectral maximum near 1600 nm was observed for both bias polarities. Infrared electroluminescence from GaSb/polymer nanocomposites points to possible applications in fibre-optic communications.

Bisaminophosphane – Synthese, Struktur und Reaktivität

Zwei unterschiedliche Synthesewege zur Darstellung von Bis(alkylamino)phosphanen RP(N(H)R′)2 werden vorgestellt. Die Kristallstruktur von t-BuP(N(H)Dipp)2 (Dipp = 2,6-(i-Pr)2–C6H3) wurde durch Einkristallrontgenstrukturanalyse bestimmt. Die Reaktivitat der Verbindungen gegenuber Organoaluminium-Verbindungen wurde exemplarisch anhand verschiedener Reaktionen von t-BuP(N(H)t-Bu)2 untersucht. Reaktionen mit Me3Al bzw. R2AlH (R = Me, Et, i-Bu) in 1 : 1- und 1 : 2-Stochiometrie fuhren jeweils zum Monosubstitutionsprodukt t-BuP(N(H)t-Bu)(N(AlR2)t-Bu). Bisaminophosphanes – Synthesis, Structure, and Reactivity Different pathways for the synthesis of bis(alkylamino)phosphanes RP(N(H)R′)2 are described. t-BuP(N(H)- Dipp)2 (Dipp = 2,6-i-Pr2–C6H3) was structurally characterized by single crystal X-ray diffraction. The reactivity of the compounds was examplarily investigated using t-BuP(N(H)t-Bu)2. Its reaction with Me3Al and R2AlH (R = Me, Et, i-Bu) in 1 : 1 and 1 : 2 stoichiometrie yield monosubstituted compounds of the type t-BuP(N(H)t-Bu)(N(AlR2)t-Bu).