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Cage Compounds (cage + compound)
Selected AbstractsExceptional Dielectric Phase Transitions in a Perovskite-Type Cage Compound,ANGEWANDTE CHEMIE, Issue 37 2010Wen Zhang Prof. Rotationsprinzip! Die organisch-anorganische Käfigverbindung (HIm)2[KFe(CN)6] (1, HIm=Imidazolium) mit Perowskit-Struktur zeigt zwei Phasenübergänge bei 158,K und 187,K (siehe Bild mit den anisotropen dielektrischen Permittivitäten des Einkristalls). Die Übergänge lassen sich auf einen Wechsel der rotierbaren Gastmoleküle zwischen geordneten und ungeordneten Zuständen zurückführen. 1 bildet eine neue Klasse von schaltbaren molekularen Dielektrika mit verblüffender Anisotropie. [source] Synthesis and Characterisation of Ternary Cage Compounds with Adamantane-Like M4P4Si2 (M = Al, Ga, In) Core StructuresEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 16 2003Carsten von Hänisch Abstract The reactions of [LiAl(PH2)4] or [NaAl(PH2)4] with Et2SiCl2 or iPr2SiCl2 yield the dialkyldiphosphanylsilanes Et2Si(PH2)2 (1) and iPr2Si(PH2)2 (2), respectively. Both compounds were identified by NMR spectroscopy as well as mass spectrometry. Compound 2 reacts with MEt3 (M = Al, Ga, In) to form the cage compounds [iPr2Si{P(H)MEt2}2]2 (3: M = Al, 4: M = Ga, 5: M = In). These three clusters were fully characterised by NMR and IR spectroscopy as well as by single-crystal X-ray diffraction. The central structural motif of 3,5 is an adamantane-like cage composed of four metal, four phosphorus and two silicon atoms. They are the first ternary clusters with these combinations of elements and crystallise isotypical in the triclinic space group P ; the lattice constants are: 3: a = 1129.0(6), b = 1164.8(8), c = 1750.6(8) pm; , = 83.63(5), , = 81.53(4), , = 73.39(5)°; 4: a = 1125.9(7), b = 1159.0(7), c = 1744.7(7) pm; , = 83.71(4), , = 81.89(4), , = 73.05(5)°; 5: a = 1147.4(2), b = 1174.7(2), c = 1753.3(4) pm; , = 85.32(3), , = 82.03(3), , = 73.40(3)°. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] Cubane-Like Bismuth-Iron Cluster: Synthesis, X-ray Crystal Structure and Theoretical Characterization of the [Bi4Fe8(CO)28]4, AnionEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 20 2010Kirill Yu. Abstract The reaction of cyclo -Bi4[Si(SiMe3)3]4 (1) with Na2[Fe(CO)4] in the presence of nBu4NCl leads to the formation of the cage compound [nBu4N]4[Bi4Fe8(CO)28] (2). According to X-ray single-crystal structure analysis, the faces of the tetrahedral Bi4 core are capped by Fe(CO)3 moieties in a ,3 fashion to give a cubanoid Bi4Fe4 framework. The four Fe(CO)4 fragments are ,1 -coordinated to bismuth, each. With 12 skeletal electron pairs the [Bi4Fe8(CO)28]4, anion (2a) is a Bi4Fe4 cubane. The negative charge is localized within cluster 2a according to the NBO analysis of its derivatives. The strength of metal,ligand interactions Bi,,3 -Fe(CO)3 is responsible for the size of the cluster's cubic core. NICS computations at the cage centers of considered molecules show that 2a has paratropic character, whereas removal of four ,1 -Fe(CO)4 fragments from latter causes spherical aromaticity of the modified clusters [Bi4Fe4(CO)12]4, (2aa) and [Bi4Fe4(CO)12]2+ (2ab), mediated by a Bi4 cluster , orbital. [source] Perfect planar tetracoordinate carbon in neutral unsaturated hydrocarbon cages: A new strategy utilizing three-dimensional electron delocalizationJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 13 2009Yang Wang Abstract A new series of unsaturated pure and boron-substituted hydrocarbons containing a perfect planar tetracoordinate carbon (ptC) have been proposed by performing density functional computations. The ptC is effectively stabilized through three-dimensional delocalization of ptC's lone pair into ,-conjugated systems, by utilizing a new strategy opening a brand new way of designing ptC structures. Compared to previously proposed ptC-containing hydrocarbon cage compound, a neutral hydrocarbon designed here might be a more viable target for synthetic attempts. © 2009 Wiley Periodicals, Inc. J Comput Chem 2009 [source] Synthesis and Characterisation of Ternary Cage Compounds with Adamantane-Like M4P4Si2 (M = Al, Ga, In) Core StructuresEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 16 2003Carsten von Hänisch Abstract The reactions of [LiAl(PH2)4] or [NaAl(PH2)4] with Et2SiCl2 or iPr2SiCl2 yield the dialkyldiphosphanylsilanes Et2Si(PH2)2 (1) and iPr2Si(PH2)2 (2), respectively. Both compounds were identified by NMR spectroscopy as well as mass spectrometry. Compound 2 reacts with MEt3 (M = Al, Ga, In) to form the cage compounds [iPr2Si{P(H)MEt2}2]2 (3: M = Al, 4: M = Ga, 5: M = In). These three clusters were fully characterised by NMR and IR spectroscopy as well as by single-crystal X-ray diffraction. The central structural motif of 3,5 is an adamantane-like cage composed of four metal, four phosphorus and two silicon atoms. They are the first ternary clusters with these combinations of elements and crystallise isotypical in the triclinic space group P ; the lattice constants are: 3: a = 1129.0(6), b = 1164.8(8), c = 1750.6(8) pm; , = 83.63(5), , = 81.53(4), , = 73.39(5)°; 4: a = 1125.9(7), b = 1159.0(7), c = 1744.7(7) pm; , = 83.71(4), , = 81.89(4), , = 73.05(5)°; 5: a = 1147.4(2), b = 1174.7(2), c = 1753.3(4) pm; , = 85.32(3), , = 82.03(3), , = 73.40(3)°. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] NMR assignments of a di-pentacyclo-undecane cyclic etherMAGNETIC RESONANCE IN CHEMISTRY, Issue 11 2006Hendrik G. Kruger Abstract The X-ray structure of a di-pentacyclo-undecane cyclic ether was recently reported. As part of a programme to use NMR spectroscopy for the structure elucidation of cage compounds, the complete NMR assignments of the cyclic ether was attempted. Major overlap of proton and carbon signals of the two cages is observed. It was required to elucidate the fragment analogues that represent similar structural features of the cyclic ether in order to get an approximate but reasonable insight into the complex overlapping signals. Normal 2D NMR techniques were utilized to assign the various NMR signals. Copyright © 2006 John Wiley & Sons, Ltd. [source] Pharmacology and structure-activity relationships of bioactive polycyclic cage compounds: A focus on pentacycloundecane derivativesMEDICINAL RESEARCH REVIEWS, Issue 1 2005Werner J. Geldenhuys Abstract The chemistry of organic polycyclic cage compounds has intrigued medicinal chemists for over 50 years, yet little is published about their pharmacological profiles. Polycyclic cage compounds have important pharmaceutical applications, ranging from the symptomatic and proposed curative treatment of neurodegenerative diseases such as Parkinson's and Alzheimer's disease (e.g., amantadine and memantine), to use as anti-viral agents against influenza and the immunodeficiency virus (HIV). The polycyclic cage appears to be a useful scaffold to yield drugs with a wide scope of applications, and can be used also to modify and improve the pharmacokinetic and pharmacodynamic properties of drugs in current use. This review attempts to summarize the pharmacological profiles of polycyclic cage compounds with an emphasis on the lesser known pentacycloundecanes, homocubanes, and trishomocubanes. © 2004 Wiley Periodicals, Inc. [source] Fluoride catalyzed rearrangements of polysilsesquioxanes, mixed Me, vinyl T8, Me, vinyl T10 and T12 cagesAPPLIED ORGANOMETALLIC CHEMISTRY, Issue 8 2010M. Ronchi Abstract Insoluble mixtures of polyvinylsilsesquioxane, -(vinylSiO1.5)n - PVS, and polymethylsilsesquioxanes, -(MeSiO1.5)n - PMS, in THF at ambient when treated with catalytic amounts (1,5 mol%) of fluoride ion introduced as tBu4 NF will depolymerize and dissolve. The resulting soluble species consist of [vinylxMe8,x(SiO1.5)]8, [vinylxMe8,x(SiO1.5)]10 and [vinylxMe8,x(SiO1.5)]12. Ratios of 1:1 of PVS:PMS greatly favor formation of vinyl rich cages. Only at ratios of 1:5 are the proportions of vinyl:Me in the cages approximately equal. Of the T8, T10 and T12 species produced, all conditions tried, including changing the solvent to EtOH or toluene or at reflux (THF), favor the formation of the larger cages sometimes completely excluding formation of the T8 materials. Efforts to isolate the cage compounds by removal of solvent regenerates polysilsesquioxanes, albeit those containing mixtures of Me and vinyl groups. Introduction of CaCl2 sufficient to form CaF2 prior to workup prevents repolymerization, allowing recovery of the mixed cage systems. The approach developed here provides a novel way to form mixed functional group silsesquioxane cages. The fact that T10 and T12 cage formation is favored appears to suggest that these cages are more stable than the traditionally produced T8 cages. Copyright © 2009 John Wiley & Sons, Ltd. [source] Gold Catalysis: Tandem Reactions of Diyne,Diols and External Nucleophiles as an Easy Access to Tricyclic Cage-Like Structures,CHEMISTRY - A EUROPEAN JOURNAL, Issue 32 2010Stephen Abstract Different diyne,diols composed of two terminal homopropargylic alcohol groups were prepared by bi-directional synthesis. Subjection of the syn diastereomers to NAC,gold catalysts (NAC=nitrogen acyclic carbene) in the presence of external nucleophiles such as water or anilines provided substituted and highly rigid heterocyclic cages. The corresponding anti disastereomers polymerised. An intermediate of the reactions of the syn diastereomers could be isolated and even be characterised by crystal structure analysis. Overall, eight new bonds are formed in the reaction, which proceeds by a multistep sequence of highly selective hydroalkoxylations and hydrohydroxylation or hydroaminations. For furyl substituents and for internal alkynes competing reaction pathways could be identified. By the cross-coupling of a product with an iodoaryl substituent, the use of these cage compounds as geometrically defined linking groups by using orthogonal transition-metal-catalysed methodology, namely, gold and palladium catalysis, could be demonstrated. [source] Cationic P,S,X cages (X=Br, I)CHEMISTRY - A EUROPEAN JOURNAL, Issue 6 2006Marcin Gonsior Dr. Abstract The first condensed-phase preparation of ternary P,Ch,X cations (Ch=O,Te, X=F,I) is reported: [P5S3X2]+, [P5S2X2]+, and [P4S4X]+ (X=Br, I). [P5S3X2]+ is formed from the reaction of the Ag+/PX3 reagent with P4S3. The [P5S3X2]+ ions have a structure that is related to P4S5 by replacing PS by P+X and S in the four-membered ring by P(X). We provide evidence that the active ingredient of the Ag+/PX3 reagent is the (H2CCl2)Ag,X,PX2+ cation. The latter likely reacts with the HOMO of P4S3 in a concerted HOMO,LUMO addition to give the P5S3X2+ ion as the first species visible in situ in the low-temperature 31P NMR spectrum. The [P5S3X2]+ ions are metastable at ,78,°C and disproportionate at slightly higher temperatures to give [P5S2X2]+ and [P4S4X]+, probably with the extrusion of 1/n,(PX)n (X=Br, I). All six new cage compounds have been characterized by multinuclear NMR spectroscopy and, in part, by IR or Raman spectroscopy. The [P5S2X2]+ salts have a nortricyclane skeleton and were also characterized by X-ray crystallography. The structure of the [P4S4X]+ ion is related to that of P4S5 in that the exo -cage PS bond is replaced by an isoelectronic P+X moiety. [source] | ||||||||||