The Yellow Polymorphs of Mercuric Iodide (HgI2)

HgI₂ crystallizes under ambient conditions from various solvents and by sublimation into three concomitant polymorphs whose colors are red, orange, and yellow. The orange and yellow phases are metastable and transform into the red phase when touched. A phase transition from red to yellow occurs at 400 K. The reverse transition from yellow to red shows a huge hysteresis. We established that the structures of the metastable yellow^M phase (determined by single‐crystal X‐ray diffraction) and the high‐temperature yellow^HT phase (determined by powder synchrotron X‐ray diffraction and second‐harmonic generation) are different, albeit closely related. Both show analogous packings of I? Hg? I molecules, which are straight in the first and bent with an angle of ca. 160° in the second. The red and orange phases are tetrahedral semiconductor structures that sublime even at room temperature. The growth of the yellow^M phase from 2‐chloroethanol and the kinetics of the reconstructive phase transition red to yellow^HT and back were studied by optical microscopy, Raman spectroscopy in solution, luminescence, and powder synchrotron X‐ray diffraction as a function of time at various temperatures. Both yellow phases grow by accretion of HgI₂ molecules, present in the solution or liberated from the red crystals, on the surface of the crystal. In contrast, the reverse transformation from yellow to red occurs in the bulk of the crystal, presumably by migration of Hg in the packing of I and subsequent rearrangement of I. The displacement parameters of Hg in both structures are considerably larger than those of I and apparently not dominated by disorder effects.     

A New Europium(II) Oxide Iodide: Eu2OI2

Red single crystals of Eu₂OI₂ were obtained from a reaction mixture of barium metal, EuI₂, Eu₄OI₆ and some NH₄I in a tantalum tube at 780/500 °C. The crystal structure (orthorhombic, Imcb, Z = 4, a = 648.93(11), b = 742.85(13), c = 1307.1(3) pm, R1(all) = 0.0605) contains {Eu₄O} tetrahedra connected via trans‐edges to infinite chains. The iodide ions surround and connect these chains to a three‐dimensional structure.     

2-(p-取代苯乙烯基)噻唑碘盐的电子光谱研究

本文测定八种2-(p-取代苯乙烯基)噻唑碘盐染料的电子光谱。研究其吸收光谱的λ_(max)与取代基常数σ之间的定量关系,以λ_(max)值对Δσ(σρ-σm)作图呈线性趋势。并发现这些染料吸收带的溶剂效应符合 Nicol 理论。     

Syntheses,Characterizations and Crystal Structures of (E)-2-Methyl-1,3-diphenylisothiouronium Iodide and 1,3-Dibenzyl-2-methylisothiouronium Iodide

Two thiouronium iodide salts,(E)-2-methyl-1,3-diphenylisothiouronium iodide(1) and 1,3-dibenzyl-2-methylisothiouronium iodide(2),were synthesized and characterized by single-crystal X-ray diffraction,1H NMR,IR,UV-vis and luminescence spectra.Single-crystal X-ray diffraction reveals that compound 1 crystallizes in monoclinic system,P21/n space group with a = 11.273(2),b = 10.318(2),c = 12.962(3) ?,β = 99.03(3)°,V = 1489.0(5) ?3 and Z = 4;compound 2 crystallizes in monoclinic system,C2/c space group with a = 11.706(2),b = 14.119(3),c = 20.930(4) ?,β = 103.84(3)°,V = 3358.8(12) ?3 and Z = 8.The thiouroniums of both compounds are Y-shaped planar structures to form a cross-conjugated system.The averaged bond lengths of C-N and C-S indicate the presence of "Y" aromaticity.The researches on UV-vis and luminescence spectra of compounds 1 and 2 indicate that they can form inclusion complex with β-CD in the aqueous solution.     

Mukaiyama Aldol Reaction of 1,2-Bis(trimethylsiloxy) Cyclobutene Catalyzed by Magnesium(II) Iodide

Theuniquereactivityof1,2-bis(trimethylsiloxy)cyclobutene(BTCB)towardscarbonylsubstrateoritsacetalequivalentunderLewisacidcatalysiswasfirstrecognizedbyKuwajimaandNakamurain19771.Thereactiongenerallyledtothegeminalacylationorreductivesuccinoylationofcarbonylsubstrateviatheacid-catalyzedpinacol-typerearrangement(acylmigration)oftheMukaiyamaaldoladductasillustratedinEq.12.OR1R2R1R2OROROR1R2OOR=TMSCO2HOR1R2L.A.acidor(1)OTMSOTMS+Furtherdevelopmentofthisreactionhasbeencarriedoutexten…     

Pd(OAc)2-Catalyzed Carbonylative Coupling of Aryl Iodide with Ortho-Haloamines in Water

The carbonylative cross coupling of aryl iodide with ortho-haloaniline to ortho-haloanilide using phosphine-free Pd(OAc)₂ catalyst in water as a reaction medium has been studied. The present protocol facilitated the reaction of o-haloanilines with a wide variety of hindered and functionalized aryl iodides, affording good yields of the desired products. The protocol was also extended for the synthesis of benzoxazoles through cyclization of ortho-haloanilide using Cu(acac)₂ catalyst.     

The Reaction of Diethylthiophosphinyl Iodide,Et2P(S)I,with Nucleophiles

The compound Me₂AsSI can exist in two different forms, either as dimethylarsinosulfenyl iodide [or (iodothio)dimethylarsane)], Me₂As–S–I ( A ), or as dimethylthioarsinyl iodide (or dimethylarsinothioic iodide), Me₂As(S)–I ( B ). To confirm that the structure of the product of the reaction between Bunsen's cacodyl disulfide Me₂As(S)–S–AsMe₂ and iodine is A and not B , the known diethylthiophosphinyl iodide (or diethylphosphinothioic iodide), Et₂P(S)–I ( 2 ) was prepared and its hydrolytic stability and reactivity towards a variety of nitrogen, phosphorus(III), arsenic(III), oxygen, and sulfur(II) nucleophiles were studied. The results indicated that only a few reactions of 2 resembled those of A , thus strengthening the proposal that the reaction of Bunsen's cacodyl disulfide with iodine produced A and not B . A series of ³¹P NMR chemical shifts of diethylthiophosphinyl moiety is also reported. Et₂P(S)–DMAP, synthesized and isolated during the presented study, is the ethyl analogue of Me₂P(S)–DMAP, previously described as an important molecule. In our case, Et₂P(S)–DMAP was found to be a good intermediate for the synthesis of phosphoryl or thiophosphoryl derivatives since it was more reactive than 2 towards nucleophiles.     

双（N—苯基—3—咔唑基）甲苯碘盐的合成

双（Ｎ┐苯基┐３┐咔唑基）甲苯碘盐的合成李笃信＊郭自强兰卫东（山西大学化学系太原０３０００６）关键词苯基咔唑甲苯碘盐，有机光电导体，敏化剂，合成１９９７－１０－２７收稿，１９９８－０３－１３修回山西省自然科学基金资助项目有机光电导体简称ＯＰＣ，因其具...