Showing papers on "Carborane published in 1991"
109 citations
TL;DR: In this paper, a series of charge-compensated, boron-substituted carborane cage derivatives, [nido-9-L-7,8-C 2 B 9 H 12 ] and [nidos-10-L 7,9-C 7,8]-with the nitrogen-containing ligand, L, were synthesized directly from the reaction of [closo-1,8−C 2B 9 H 11 ] with the nitrogen containing ligand.
Abstract: A series of charge-compensated, boron-substituted carborane cage derivatives, [nido-9-L-7,8-C 2 B 9 H 11 ] or [nido-10-L-7,8-C 2 B 9 H 11 ] (L=nitrogen-containing ligand), were prepared by the ferric chloride-promoted oxidative coupling reaction of K[nido-7,8-C 2 B 9 H 12 ] with the Lewis base, L. Another series of neutral boron-substituted carborane cage derivatives, [nido-10-L-7,9-C 2 B 9 H 11 ], were synthesized directly from the reaction of [closo-1,8-C 2 B 9 H 11 ] with the nitrogen-containing ligand, L
84 citations
TL;DR: Fluoride ion, in aprotic solvents, has been found to be effective in the cage opening of closo-carboranes such as 1,6-C 2 B 4 H 6, 2,4-C 3 B 5 H 7, 1,2-C 1 B 10 H 12 , and 1,7-C2 B 10H 12 .
Abstract: Fluoride ion, in aprotic solvents, has been found to be effective in the cage opening of closo-carboranes such as 1,6-C 2 B 4 H 6 , 2,4-C 2 B 5 H 7 , 1,2-C 2 B 10 H 12 , and 1,7-C 2 B 10 H 12 . Nearly quantitative conversion to nido-carboranes is observed; in the case of 1,6-C 2 B 4 H 6 the product is the [5-F-nido-2,4-C 2 B 4 H 6 ] − ion. In the case of the higher carboranes the nido-carborane produced is that expected from the removal of a single vertex boron
72 citations
TL;DR: A carborane version of dehydrobenzene, 1,2-dehydro-o-carborane, has been generated from (2-bromo-ocarboranyl) lithium.
Abstract: A carborane version of dehydrobenzene, 1,2-dehydro-o-carborane, has been generated from (2-bromo-o-carboranyl) lithium. This new intermediate undergoes the ene reaction as well as 2+2 and 2+4 cycloadditions. The 2+2 cycloaddition is nonstereospecific, whereas the 2+4 cycloaddition likely proceeds with retention of stereochemistry
59 citations
56 citations
TL;DR: In this article, a modified, high-yield synthesis of the two isomeric nido twelve-vertex [C2B10H13]- anions, "reactive" [nido-7,9-C2H10B13]- and "unreactive", has been developed, based on the result of two-dimensional 11B and 1H correlation NMR spectroscopy.
Abstract: A modified, high-yield synthesis of the two isomeric nido twelve-vertex [C2B10H13]- anions, "reactive" [nido-7,9-C2B10H13]- and "unreactive" [nido-7,12-C2B10H13]-, has been developed. A solution structure for the reactive [nido-7,9-C2H10B13]- isomer is proposed on the basis of the result of two-dimensional 11B and 1H correlation NMR spectroscopy. It is concluded that there is a marked similarity between this species and the eleven-vertex congener [nido-7,8-C2B9H12]-. In accord with this parallel, the "reactive" twelve-vertex species is found to undergo selective boron-vertex elimination reactions in the presence of oxidizing agents. These reactions give excellent yields of smaller-cage nido dicarbaborane compounds, namely [nido-7,8-C2B9H12]-, [9-(SMe2)-nido-7,8-C2B9H11], and nido-5,6-C2B8H12. NMR spectroscopy assigns cluster 11B and 1H resonances for all the compounds isolated, and thence permits comparison with the equivalent shielding patterns of structurally related analogues such as [nido-7-CB10H13]- and [nido-7,9-C2B9H12]-.
54 citations
50 citations
TL;DR: In nude mice bearing GW-39 tumor xenografts the conjugate containing the anionic carborane derivative showed a reduced tumor uptake although the tumor:non-tumor ratio was similar to that of the native antibody.
48 citations
47 citations
45 citations
TL;DR: In this article, Boron in the form of a carborane compound, C2B10H12, was used to catalytically graphitize a polyarylacetylene (PAA) resin, typically a nongraphitizing carbon, in bulk form and in a carbon-carbon composite.
TL;DR: In this paper, the HOMO of the [9-SMe2-7,8-nido- C2B9H10]t- ligand has been analyzed and the copper atom is essentially symmetrically disposed above the five-atom ligand face, thus completing a closo 12 vertex polyhedron.
TL;DR: The salt [NEt4][10-endo-{Au(PPh3)}-7,8-nido-C2B9H9Me2] has been used to synthesise several complexes in which gold forms bonds with rhodium and iridium.
Abstract: The salt [NEt4][10-endo-{Au(PPh3)}-7,8-nido-C2B9H9Me2] has been used to synthesise several complexes in which gold forms bonds with rhodium and iridium, including [IrAuH(µ-σ,η3-C2B9H8Me2)(PPh3)3], [exo-nido-5,10-{Rh(PPh3)2}-5,10-µ-(H)2-10-endo-{Au(PPh3)}-7,8-C2B9H7Me2]·CH2Cl2, and [RhAu2(µ-H)(PPh3)3(η5-C2B9H9Me2)]·2(CH2Cl2).
TL;DR: In this paper, the same authors showed that the exo-diphosphineplatinum-closo-monocarbaborane complexes (CB11H12) can be protonated in diethyl ether at 0 °C.
Abstract: Protonation of the complexes [PtR2(L–L)][R = Me, L–L =(C6H11)2P(CH2)3P(C6H11)21a; But2P(CH2)3PBut2, 1b; But2P(CH2)2PBut21c; or But2PCH2C6H4CH2PBut2, 1d; R = CH2But, L–L =(C6H11)2P(CH2)3P(C6H11)2, 2a; But2P(CH2)3PBut2, 2b; or But2P(CH2)2PBut2, 2c] with the monocarbaborane acid HCB11H12 in diethyl ether at 0 °C affords the exo-diphosphineplatinum-closo-monocarbaborane complexes [Pt(L–L)(closo-CB11H12)][CB11H12][L–L =(C6H11)2P(CH2)3P(C6H11)2, 3a, But2P(CH2)3PBut2, 3b; But2P(CH2)2PBut23c; or But2PCH2C6H4CH2PBut2, 3d] in which the co-ordinated closo-CB11H12 ligand is strongly bond to platinum via two exo-polyhedral three-centre two-electron (Pt ⋯ H ⋯ B) bridges. These complexes are fluxional in solution at room temperature. A single-crystal X-ray diffraction study of 3c confirmed the bonding mode of the dodecarboraneligand. Complex 3c crystallizes in the monoclinic space group C2/c, a= 16.199(4), b= 16.564(5), c= 14.896(3)A, β= 93.64(2)° and Z= 4. The final discrepancy index was R= 0.043, R′= 0.050 for 2838 independent reflections. The geometry around the platinum centre is distorted square planar with µ-H–Pt 1.90(8), Pt–B 2.342(8) and B-µ–H 1.23(8)A. In contrast when the solvent is changed from ether to tetrahydrofuran (thf), complex 1b on protonation is converted into [PtMe(thf){But2P-P(CH2)3PBut2}][CB11H12]5. Complexes 3b-3d react with acetonitrile to yield [Pt(NCMe)2(L–L)][CB11H12]2[L–L = But2P(CH2)3PBut2, 6b; But2P(CH2)2PBut2, 6c; or But2CH2C6H4CH2But2, 6d]. Likewise 3b reacts with pyridine affording [Pt(NC5H5)2{But2P(CH2)3PBut2}][CB11H12]27. However C2H4, CO and PPh3 do not react readily with these complexes. The thf complex 5 reacts with deuteriated acetonitrile to form [PtMe(NCCD3){But2P(CH2)3PBut2}][CB11H12]8. Spectroscopic data for the new complexes are presented and discussed.
TL;DR: In this paper, the monocarbaborane arachno-4-CB8H14 with either sodium nitrite or elemental sulphur in the presence of triethylamine results in the isolation of two representatives of the ten-vertex arachnos family of cluster carbaheteroboranes, 6,9-CNB8H13 and 6, 9-CSB8H12.
Abstract: Treatment of the monocarbaborane arachno-4-CB8H14 with either sodium nitrite or elemental sulphur in the presence of triethylamine results in the isolation of two representatives of the ten-vertex arachno family of cluster carbaheteroboranes, 6,9-CNB8H13 and 6,9-CSB8H12, the constitution of which has been established on the basis of 1H, 11B, [11B–11B]-COSY, and [1H–1H]-COSY NMR data and mass spectroscopic measurements.
TL;DR: Carboran-9-yl derivatives of nontransition metals, 9-fluoro-, 9thiocyano-, 9-trifluoroacetoxy-carboranes and bis(carboran 9-y1)tellurides as well as the known 9-hyd- roxy-, 9mercapto- and 9-iodocarboranes were synthesized as mentioned in this paper.
Abstract: Carboranyl derivatives of mercury and thallium have been obtained by mercuration and thallation of carbora- nes(l2) in the 9 position of the carborane cage. The substitu- tion of metal atom in boron-mercurated and boron-thallated carboranes allowed a great variety of B(g)-substituted carbo- ranes to be prepared. The previously unknown carboran-9-yl derivatives of nontransition metals, 9-fluoro-, 9-thiocyano-, 9-trifluoroacetoxy-carboranesI bis(carboran-9-y1)diselenides and bis(carboran 9-y1)tellurides as well as the known 9-hyd- roxy-, 9-mercapto- and 9-iodocarboranes were synthesized. In many cases, the reactions occur under radical conditions (photolysis, pyrolysis) to give B(9)-centered radicals which undergo further transformation.
TL;DR: In this paper, a method for the construction of multidecker-, multilevel-, and linked-sandwich complexes from transition metals, aromatic hydrocarbon or heterocyclic ligands, and carborane (C2B3) rings is presented.
Abstract: Methods are now at hand to permit the systematic construction of multidecker-, multilevel-, and linked-sandwich complexes from transition metals, aromatic hydrocarbon or heterocyclic ligands, and carborane (C2B3) rings. As a consequence of detailed studies of the electronic properties and chemistry of selected building-block complexes, especially those of the type LM(R~C~BS%R'), where L is C5R5 or an arene and M is a first-, second-, or third-row transition element, the reactivity of such compounds can be adjusted, or "tuned, by attachment of appropriate R' substituents to boron; this allows the controlled synthesis of a variety of types of polymetallic systems which exhibit substantial electron-delocalization. These include triple- and tetradecker complexes, poly(sandwich) species linked via organic units attached at boron or carbon positions, and related systems. This chemistry in turn opens the way to the preparation of extended molecular solid or liquid materials which can be tailored to combine unusual or novel electronic properties with high thermal and oxidative stability.
TL;DR: In this article, the synthesis of unknown types of carboranyl derivatives of non-transition metals was carried out and the pro- perties of the carborane derivatives with the carbon-nontransition metal 6-bond and the boron-metal bond were compared.
Abstract: The synthesis of the unknown types of carboranyl derivatives of nontransition metals was carried out. The pro- perties of carborane derivatives with the carbon-nontransition metal 6-bond, on the one hand, and the boron-metal bond, on the other, were compared. Boron-carboranyl derivatives of non- transition metals were shown to react with different reagents similar to organometallic compounds.
TL;DR: The electronic structure of polyhedral carboranes was studied using ab initio calculations, and compared to that of their hydrocarbon analogs bicyclo[1.1] butane and [1]propellane, respectively.
Abstract: The electronic structure of the polyhedral carboranes 1,5-dicarba-closo-pentaborane(5) and 1,5-dicarba-closo-pentaborane(3) is studied using ab initio calculations, and compared to that of their hydrocarbon analogs bicyclo[1.1.1]pentane and [1.1.1]propellane, respectively. The high symmetry and common topology of the carborane-hydrocarbon structural analogs force similar bonding patterns, and the carboranes show a unique three-center, two-electron CBC bond not previously observed in these species. This three-center bond is formally analogous to the σ-bridged-π bond in the hydrocarbons, but its strength is low and its CC bond long. Analysis of the bonding in these carboranes along with that in 1,3-diborabicyclo[1.1.1]pentane, another[1.1.1]propellane analog, shows that the strength of their three-center bonds is directly related to the nature of the bridging group, but is independent of the type of bridgehead atom. 1,3-Diboretene, the carborane analog of bicyclo[1.1.0]butane, is also found to exhibit a similar bonding pattern to its hydrocarbon analog and to possess a CBC bond.
TL;DR: In this article, the boron atom was removed from position six of the polyhedron with the formation of a salt of 3-amino-7,8-dicarbaundecaborate.
Abstract: Cleavage of 3-amino-o-carborane by alcoholic alkali results in preferential elimination of the boron atom from position six of the polyhedron with the formation of a salt of 3-amino-7,8-dicarbaundecaborate and, to a smaller degree, to elimination of the boron bonded to the NH2 group, which leads to formation of a salt of 7,8-dicarbaundecaborate. Cleavage of 3-amino-o-carborane by piperidine is even more regioselective. Cleavage of N-derivatives of 3-amino-9-carborane by alcoholic alkali or piperidine is regiospecific, leading to salts of N-substituted 7,8-dicarbaundecaborates. 3-Ammonium-7,8-dicarbaundecaborate and a number of its N-derivatives were isolated in zwitterion form for the first time.