Role of the substrate in the formation of structure defects representing step retardation sites during vapor phase epitaxy of gallium arsenide

A direct experimental proof was obtained (in the specific case of GaAs) of the dominant role of the substrate surface in the formation of defects representing step retardation sites during vapor phase epitaxy of III–V compounds.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 64–65, January, 1992.     

Synthesis and Structure of μ-Oxobis[triphenyl(furfuraloximato)antimony(V)]

Reaction of triphenylstibine with furfuraloxime in the presence of hydrogen peroxide in water-ether solution forms -oxobis[triphenyl(furfuraloximato)antimony(V)] in 90% yield. This complex has a dimeric structure in which two antimony atoms are bound with the bridge oxygen atom and two bridge oxime groups coordinating the metal atom by the oxygen as well as by the nitrogen atoms to form bicyclo[2.2.1]heptane fragment. SbOSb angle is 125.5(3)°, the bonds between the antimony atom and the bridge oxygen atoms [1.957(6) and 1.946(5) Å] are shorter than with the oxygen atoms of oxime groups [2.146(6) and 2.148(6) Å].     

Crystal and molecular structures of the potassium salt of 2-methoxy-4-dimethylamino-6-dinitromethyl-1,3,5-triazine

The X-ray diffraction study of the potassium salt of 2-methoxy-4-dimethylamino-6-dinitromethyl-1,3,5-triazine is carried out. The crystals are triclinic; C₇H₉N₆O ₅ ^? ·2K⁺·2H₂O; a = 7.645(7) Å, b = 8.230(7) Å, c = 12.435(9) Å; α = 99.99(8)°, β = 91.52(7)°, γ = 113.86(8)°; V = 701(1) ų, ρ_calc = 1.58 g/cm³, Z = 2, space group P-1. The compound crystallizes as a crystalline hydrate with two water molecules. Two planar fragments of dinitromethyl and 2-methoxy-4-dimethylamino-1,3,5-triazine construct the anion. Their geometrical parameters are explored. The coordination of potassium cations and numerous hydrogen bonds are found which result in the development of a complex 3-D framework.     

Facile and Convenient Synthesis of Functionalized Aryl-Containing Isoindigo Derivatives via Substituted Indolin-2-one Carbene Dimerization

The reaction of substituted benzyl-, aroylmethyl-, or 1-phenetylisatins with hexaethyltriaminophosphine has been shown to lead to the formation of a library of 3,3′-biindolinylidene-2,2′-diones with functionalized benzyl-, aroylmethyl-, and 1-phenetyl fragments at the nitrogen atom.     

Synthesis, structure, and antibacterial activity of aminobenzofuroxan and aminobenzofurazan

The amination of 4,6-dichloro-5,7-dinitrobenzofuroxan and 4,6-dichloro-5,7-dinitrobenzofurazan with dibenzylamine followed the aromatic nucleophilic substitution pattern (S_NAr) and gave products of replacement of both chlorine atoms in the six-membered ring with elimination of hydrogen chloride. Regardless of the reactant ratio, 4,6-dichloro-5,7-dinitrobenzofuroxan was converted into 4,6-bis(dibenzylamino)-5,7-dinitrobenzofuroxan, whereas 4,6-dichloro-5,7-dinitrobenzofurazan under analogous conditions gave rise to unusual bisammonium derivative which lost proton from the amino group on C⁴ and benzyl group from the amino group on C⁶; as a result, the corresponding diamine with secondary and tertiary nitrogen atoms was obtained. The structure of the isolated compounds was determined by IR and NMR spectroscopy, elemental analysis, and X-ray analysis; their thermal stability was studied by simultaneous thermogravimetry and differential scanning calorimetry.     

Disilyl dithiophosphonates in the synthesis of open chain and cyclic organothiophosphorus compounds

O-(Trimethylsiloxy)alkyl S-trimethylsilyl aryldithiophosphonates 7a–d were obtained by the reaction of 2,4-diaryl-1,3,2,4-dithiadiphosphetane-2,4-disulfides 5a,b with disilyl derivatives of glycols 6a,c and salicyl alcohol 6b . The reactions of mixed O,S-bis(trimethylsilyl) 2,4-di(3,5-di-tert-butyl-4-hydroxyphenyl)dithiophosphonate 1 and S-silyl aryldithiophosphonates 7a,b with S,S-diethyldithiodiphenylgermane 2 , dichlorodiphenylgermane 8a , and dichlorodiphenylstannane 8b were studied. The structure of hexaphenyl-2,4,6,1,3,5-trithiatrigerminane 11 was established by X-ray single crystal diffraction. © 2004 Wiley Periodicals, Inc. Heteroatom Chem 15:225–232, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20009     

Synthesis and thermal stability of S‐trimethylsilyl esters of tetracoordinated phosphorus amidothioacids

S‐(Diethylamino)dimethylsilyl bis(diethylamido)dithiophosphate 3 was obtained by the reaction of tetraphosphorus decasulfide 1 with bis(diethylamino)dimethylsilane 2a . The reactions of Lawesson's reagent 5 with 2a and the alkyl homologues of Davy's reagent 8a,b with trimethyl(diethylamino)silane 6 were studied. On the basis of these reactions, methods of synthesizing S‐(diethylamino)dimethylsilyl or S‐(diethylamino)diphenylsilyl 4‐methoxyphenyl (diethylamido)dithiophosphonates 7a and 7b and S‐trimethylsilyl S‐alkyl(diethylamido)trithiophosphates 9a,b are described. The optimal reaction conditions and thermal stability of S‐trimethylsilyl S‐ethyl(diethylamido)trithiophosphate 9a were defined by differential thermal analyses. Compound 9a have been decomposed to form 2,4‐bis(diethylamido)‐1,3,2,4‐dithiadiphosphetane‐2,4‐disulfide 10 which structure was established by X‐ray single crystal diffraction. © 2006 Wiley Periodicals, Inc. Heteroatom Chem 17:670–675, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20231