Showing papers on "Carborane published in 1990"
96 citations
75 citations
67 citations
TL;DR: A sterically hindered ester of 2,4-bis-(α,β-dihydroxyethyl)deuteroporphyrin IX containing four carborane cages is prepared by the reaction of the acid chloride of 1,2-dicarba-closo-dodecaborane-carboxylic acid with the bis-glycol in the presence of 4-dimethylaminopyridine as mentioned in this paper.
Abstract: A novel, sterically hindered ester of 2,4-bis-(α,β-dihydroxyethyl)deuteroporphyrin IX containing four carborane cages is prepared by the reaction of the acid chloride of 1,2-dicarba-closo-dodecaborane-carboxylic acid with the bis-glycol in the presence of 4-dimethylaminopyridine.
66 citations
50 citations
TL;DR: The first Group IVA analog of an o-carborane is 1,2-dimethyl-1,2disila-closo-dodecaborane(12) as discussed by the authors.
Abstract: : The icosahedral carboranes, especially those in which the two cluster carbon atoms are vicinal (o-carboranes), have received much attention since the first reports of their existence in 1963. Notably absent in the many publications on this class of boron cluster compounds over the intervening 25 odd years have been examples of icosahedral clusters in which the two monosubstituted carbon atoms of an o-carborane have been replaced by two monosubstituted silicon, germanium, tin or lead atoms. We report here the synthesis and structural characterization of 1, the first such Group IVA analog of an o-carborane: 1,2-dimethyl-1,2-disila-closo-dodecaborane(12) (or 1,2- dimethyl-o-silaborane). This compound is notable also in that it is the first example of a formal derivative of a disilyne, CH3Si triple bonds SiCH3 in the present case, a class of unsaturated organosilicon compounds of which there are to date no known examples. Keywords: Carboranes, Silaboranes, Organosilicon compounds, Organic chemistry, Silicon, Boron.
33 citations
TL;DR: The main group (groups 2 and 13-16) heterocarboranes have been extensively characterized and their reaction chemistry explored since 1982 as discussed by the authors, but the corresponding aluminacarborane in the pentagonal bipyramidal system has proved to be illusive.
Abstract: Publisher Summary This chapter discusses the research on the main group (groups 2 and 13–16) heterocarboranes published since 1982. It focuses on the structural and bonding features of these compounds and on their reaction chemistry. Carboranes, or carbaboranes, are mixed hydrides of carbon and boron in which atoms of both elements are incorporated in an electron-deficient molecular skeleton. There is a simple relationship between the number of skeletal electron pairs and the geometry. Among group 2 elements, only beryllium is known to have been inserted into a carborane polyhedron. Although the icosahedral commo– and closo–aluminacarboranes have been extensively characterized and their reaction chemistry explored, the corresponding aluminacarboranes in the pentagonal bipyramidal system have proved to be illusive. All elements in group 14 have been inserted into carborane cages. A group 15 atom is isoelectronic and isolobal with a CH group. Of all the main-group heterocarboranes, those of group 16 are the least studied. There has been a great deal of recent interest in the preparative chemistry and structural investigations of the main-group heterocarboranes.
32 citations
TL;DR: In this paper, the planned syntheses, structural characterization, and electrochemistry of new homo-and heterobimetallic triple-decker species bridged by C 2 B 3 or C 3 B 2 rings are described.
Abstract: The planned syntheses, structural characterization, and electrochemistry of new homo- and heterobimetallic triple-decker species bridged by C 2 B 3 or C 3 B 2 rings are described. Reactions of the carborane monoanions nido-R 2 C 2 B 4 H 5 − and the diborolyl monoanion CpCo(Et 2 MeC 3 B 2 Et 2 ) − in cold THF produced the dicobalt diamagnetic 30-electron «hybrid» sandwiches as green crystalline solids
30 citations
TL;DR: This bis(dicarbollide)silicon sandwich compound commo-3,3'-Si(3,1,2-SiC 2 B 9 H 11 ) 2 (1) has been prepared and structurally characterized by a single-crystal X-ray diffraction study.
30 citations
TL;DR: In this article, He I and He II photoelectron spectra of 1,12-B 12 H 10 (CO) 2 and 1,2-and 1,7-C 2 B 10 H 12 are assigned in terms of correspondence of bands to BH bonding or cluster-localized orbitals.
Abstract: The He I and He II photoelectron spectra of 1,12-B 12 H 10 (CO) 2 and 1,2- and 1,7-C 2 B 10 H 12 are assigned in terms of correspondence of bands to BH bonding or cluster-localized orbitals. The experimental assignments are found to agree excellently with MNDO calculations on the molecules, which allows assignment of the cluster orbitals and ionizations in terms of Ston's theory of closo-boranes. Spectra of the related closo-heteroboranes 1,2-X(CH)B 10 H 10 (X=P,As,Sb, X 2 B 10 H 10 (X=As,Sb), and SeB 11 H 11 are found to be very similar, also agreeing with calculated results. The lone pairs of the heteroatoms are found to be localized in the valence s atomic orbital. An ordbital diagram for B 12 H 12 2− is extrapolated from these results, which shows it to be distinctly different from the smaller closo-borane anions
26 citations
TL;DR: The reaction of o- and m-carboranes with antimony pentafluoride results in replacement of hydrogen by fluorine at the boron atoms as mentioned in this paper.
TL;DR: In this article, a single crystal X-ray diffraction study of the CH 2 Cl 2 solvate was performed and the structure was refined to R = 0.0487 using 4667 observed reflections.
TL;DR: In this paper, the preparation of water-soluble nido-carborate containing cyclic thioureas is described, which exemplifies the possibilities to introduce boron into molecules for their use in neutron capture therapy.
TL;DR: In this article, the specific features of thermal behavior of carborane-containing polymers and the stabilizing effect of the Carborane groups as exemplified by arylene carboranes are discussed.
Abstract: The paper discusses the specific features of thermal behaviour of carborane-containing polymers and the stabilizing effect of the carborane groups as exemplified by arylene carboranes. The results obtained explain as a whole the stabilizing effect of aromatic polymers by carborane-containing additives.
TL;DR: In this paper, the molecular structure of tetramethylammonium 7,8-(3′,6′,9′-trioxaundecane-1′,11′ -dithiolato-SS′)-dicarba-nido-undecaborate has been determined.
TL;DR: The reactivity of the anion 7,8-(ethane-1,2′-dithiolato-SS′)-dicarba-nido-undecaborate is reported as mentioned in this paper.
TL;DR: The palladium-catalyzed reaction of 1,2-dicarbora-closo-dodecaboranes (o-carboranes) with allyl ethyl carbonate (3) gave 2-allylated o-Carboranes (2) in good to excellent yields.
Abstract: The palladium-catalyzed reaction of 1,2-dicarbora-closo-dodecaboranes (o-carboranes) (1) with allyl ethyl carbonate (3) gave 2-allylated o-carboranes (2) in good to excellent yields. Compounds 2 could be converted to the corresponding diols, which were soluble in water and thus could be utilized as carriers for 10 B neutron capture therapy
TL;DR: In this article, three procedures for the esterification of polyhedral carborane carboxylic acids with long chain unsaturated fatty alcohols are compared with regard to rate of reaction, ease of isolation and over-all yield.
TL;DR: The carborane anions react with PbCl 2 to produce the corresponding closo-plumbacarboranes, 1-Pb-2,3-(SiMe 3 ) 2 -2.3-C 2 B 4 H 4 2,2'-bipyridine in yields ranging from 61 to 84% as mentioned in this paper.
TL;DR: In this article, the MNDO-SCF molecular orbital calculations were carried out on the model compounds 1-(C12H8N2)Sn-2,3-C2B4H6, 1-[C10H 8N2)-SnC5(CH3)5]- to determine what factors dictate the structures of these complexes.
Abstract: Closo-1-Sn-2,3-[Si(CH3)3]2-2,3-C2B4H4 (1) reacts with 1,10-phenanthroline to form the complex 1-(C12H8N2)Sn-2, 3-[Si(CH3)3]2-2,3-C2B4H4. When crystals of this complex were grown slowly from benzene, a crystalline modification (2) was obtained in which the unit cell consisted of four identical molecules of the base-stannacarborane and six benzene molecules of solvation. When the complex was sublimed, a second crystalline modification (3) was obtained whose unit cell consisted of two crystaliographically different molecules (3-1 and3-2). In all three forms the tin was not symmetrically bonded to the carborane but was slipped toward the boron side of the C2B3 face, and the phenanthroline molecules were oriented opposite to the cage carbons so that the plane of the base and the carborane faces gave acute dihedral angles. However, the three forms showed a great deal of variation in the extent of slippage and the magnitudes of the base-carborane dihedral angles. Since these distortions are common structural features of base-group 14-carborane and cyclopentadienyl systems, MNDO-SCF molecular orbital calculations were carried out on the model compounds 1-(C12H8N2)Sn-2,3-C2B4H6, 1-[C10H8N2)Sn-2, 3-C2B9H11, and [(C10H8N2)-SnC5(CH3)5]+ to determine what factors dictate the structures of these complexes. The results showed that competing bonding interactions give rise to a very broad minimum in energy as a function of slippage and base orientation. Small energy variations, such as those produced by crystal packing forces, could produce large structural changes. Complex2 crystallizes in the monoclinic space group P21/n witha=11.096 (9) A,b=26.51(2) A,c=11.729 (7) A,β=107.43 (6) ∘,U=3291 (4) A3, andZ=4. Full-matrix least-squares analysis converged atR=0.044 andRw=0.055. Complex3 crystallizes in the triclinic space group P¯1 witha=10.251 (3) A,b= 13.845(9) A;c=19.168 (9) A,α=71.12 (5) ∘,β=89.29 (3) ∘,γ=84.62 (4) ∘,U=2562 (2) A3, andZ=4. The structure refined atR=0.079 andRw=0.125.
TL;DR: The unbridged germacarborane complexes 1-Ge-(2,2'-C 8 H 6 N 4 )-2,3-(SiMe 3 ) 2 -2, 3-C 2 B 4 H 4 ) as discussed by the authors were synthesized in a respective ratio of 2:1 at room temperature in benzene solution over a period of 7-8 days.
TL;DR: In this paper, three new viable synthetic routes to the small closo-carborane 2,3-Et 2 C 2 B 5 H 5 (I) were reported based on cluster expansion reactions of the small nido-CARborane using Lewis base-borane adducts.
Abstract: Three new viable synthetic routes to the small closo-carborane 2,3-Et 2 C 2 B 5 H 5 (I) are reported based on cluster expansion reactions of the small nido-carborane 2,3-Et 2 C 2 B 4 H 6 utilizing Lewis base-borane adducts
TL;DR: In this paper, the position of boron substitution in 7-Me3N-7-CB10H12 derivatives was investigated using 11B-11B correlation n.m.r.
Abstract: Controlled substitution of the monocarboranes [nido-7-CB10H13]–, nido-7-Me3N-7-CB10H12, and closo-1 -Me3N-1-CB11H11has been achieved by chemical and electrochemical means. The position of boron substitution in 7-Me3N-7-CB10H12derivatives depends on the experimental method. Chloride substitution at B(4) was achieved by electrophilic (electrochemical) methods, whereas HCl–AlCl3resulted in substitution at B(9). Substitution at B(8) was obtained through a nido-closo-nido sequence of oxidation and ligand addition. The compounds were structurally characterised by 11B–11B correlation n.m.r. spectroscopy. The experimental data were correlated with AM1 calculations.
TL;DR: In this paper, the B(5)-methyl complexes of Fe, Ru, and Co were each further alkylated via deprotonation/alkyl halide treatments, to give successively the B (4,5)-dimethyl and B(4, 5,6)-trimethyl derivatives as desired.
TL;DR: In this article, a meta-carboranylene-bridged aromatic polyazomethines having inherent viscosities ranging from 0.2 to 0.5 dl · g−1 (M n = 5000 − 30,000 ) were synthesized by solution polycondensation of 1,7-dicarbadodecaborane(12)-1, 7-Dicarboxaldehyde with aromatic diamines.