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  • 1
    Electronic Resource
    Electronic Resource
    Derivatives of Aza-nido-tetraborane and Diaza-arachno-pentaborane from Tri-tert-butylazadiboriridine (1995)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 128 (1995), S. 1-9 
    Details
    ISSN: 0009-2940
    Keywords: 1-Aza-nido-tetraboranes ; 2,5-Diaza-arachno-pentaboranes ; 2,5-Diaza-nido-hexaboranes ; Boryl[diborane(4)yl]amine ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Lewis acids RBH2 are added to the basis B-B bond of tri-tert-butylazadiboriridine, NB2tBu3 (1a), to give 5-alkyl-1,2,3-tri-tert-butyl-1-aza-nido-tetraboranes of type 3 (two endo-H atoms at B5) or type 4 (one H atom in a B2-B5 bridging position, one exo-H atom at B5), either as a mixture of 3 and 4 (3, 4b-d: R = Me, tBu, CMe2iPr) or with the isomer 4 in high excess (4e, f: R = Ph, sBu). The reaction of dialkylboranes R2BH with 1a yields 5,5-dialkyl-1,2,3-tri-tert-butyl-1-aza-nido-tetraboranes of type 4 (one H atom in a B2-B5 bridging position; 4g, h: R2 = Et2, cycloocta-1,5-diyl). In boiling THF, trialkylboranes BR3 transform 1a into NB2tBu2R which, expectedly, dimerizes spontaneously to give a dialkyltetra-tert-butyl-2,5-diaza-nido-hexaborane of type 2 (2a, b: R = Me, Et). The products of the addition of aminoboranes H2B=NRR' to 1a are identified as alkyl derivatives of 2,5-diaza-arachno-pentaborane, N2B3tH2tBu3RR' (5a-d, R/R' = H/Pr, H/tBu, Me/Me, Et/Et). The aminoborane H2B = NiPr2 with a sterically more demanding amino group hydroborates the B-B bond of 1a to give the acyclic product iPr2N=BH-B(tBu)-N(tBu)=B(tBu)H (6). In contrast to the B atoms, the N atoms in the electron-deficient cluster skeletons of 2-5 need not take part in (3c,2e) bonds of the s̰ type. The molecular structures of 4c, 5d, and 6 are confirmed by X-ray structural analyses.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19951280102
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  • 2
    Electronic Resource
    Electronic Resource
    Protolysis of Tri-tert-butylazadiboriridine: Formation of a B-H-B Bridge in Unusual Coordination (1995)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 128 (1995), S. 99-103 
    Details
    ISSN: 0009-2940
    Keywords: Tri-tert-butylazadiboriridine ; (Hydroboryl)(methoxyboryl)amine ; 2,3-μ-Hydro-1,2,3-azoniadiborata-l-cyclopropenes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The B—B bond of tri-tert-butylazadiboriridine [—NR—BR—BR—] (R = tBu; 1) is oxidized by MeOH to give the (hydroboryl)(methoxyboryl)amine H—BR=NR-BR(OMe) (2a). μ-2,3-Hydroazoniadiborata-1-cyclopropenes [=NR—BR(X)—μH—BR=] (3a, 3c-e) are formed by the action of the acids HX upon 1. A similar hydrogen bridge as in 3a-e is formed during the hydroboration of 1 by catecholborane, yielding 3f. A B atom is identified in the products 3a-f to be planarly coordinated by four atoms, two of which are forming a BHB three-center bond with that B atom. This is a novel bonding situation in boron chemistry. The structures of the products are deduced from 1H-, 11B-, and 13C-NMR spectra and are confirmed by X-ray structural analyses of 2a, 3a, and 3c.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19951280203
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  • 3
    Electronic Resource
    Electronic Resource
    Auf- und Abbau von Azadecaboranen; Aza-nido-nonaboratFrau Professor Marianne Baudler zum 75. Geburtstag gewidmet. (1995)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 128 (1995), S. 1221-1224 
    Details
    ISSN: 0009-2940
    Keywords: 10-Organo-10-aza-nido-nonaborates ; 6-Alkylamine-4-aryl-4-aza-arachno-nonaboranes ; 1-Orgaro-1-aza-closo-decaboranes ; 6-Aryl-6-aza-nido-decaboranes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis and Degradation of Azadecaboranes; Aza-nido-nonaborateThe boranes arachno-B9H13(NRH2 (1a-c: R = p-ClC6H4, p-MeC6H4, PhCH2) are dehydrogenated at 140°C to give nido-RNB9H11 (2a-c), from which the azaboranes closo-RNB9H9 (3a-c) are formed on further dehydrogenation at 460°C. These azaboranes are deboronated either by the attack of the amine iPrNH2 or by one of the fluorides [NBu4]F or [S(NMe2)3][Me3SiF2] in THF. One of the four boron atoms adjacent to nitrogen in the closo species is removed and then detected in the borazine (HNBiPr)3 or the borate BF4, respectively, whereas the novel anions nido-RNB8H9 (4a-c) remain. The structure of 4a-c corresponds to that of nido-SB8-H9-, according to NMR spectra. Primary amines R'NH2 deboronate the closo-boranes 3a, b in a solvent less polar than THF to give the amine - azanonaboranes arachno-RNB8H10-(NR'H2) (5a-c: R' = iPr, Pr, Bu). The nido product [iPrNH3][(p-ClC6H4)NB8H9 is converted into a mixture of the arachno products 5a and (p-ClC6H4)NB8H10(NPrH2) (5d) by the action of PrNH2, making plausible that anions of type 4 are intermediates during the transformation of 3 into 5.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19951281213
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  • 4
    Electronic Resource
    Electronic Resource
    Tri-tert-butylazadiboriridin: Ringerweiterung mit Isonitrilen, α-Bromlithioalkanen und Aziden (1995)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 128 (1995), S. 1029-1035 
    Details
    ISSN: 0009-2940
    Keywords: Azadiboracyclobutanes ; Azadiboracyclopentanes ; Azadiboriridine, ring-opening of ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Tri-tert-butylazadiboriridine: Ring Prolongation by the Action of Isonitriles, α-Bromolithioalkanes, and AzidesIsonitriles ArNC are 1,1-boroborated by the B-B bond of the azadiboriridine (-BR-BR-NR-) (1; R = tBu) to form the four-membered ring [-BR-C(NAr)-BR-NR-] (2b; Ar = 2,6-C6H3Me2). Corresponding rings undergo [3 + 3] cyclodimerization of the B-C=N chain to give the tricyclic products 6a, b when isonitriles RNC with the small ligands R = Me, Et are boroborated by 1. Two molecules of tBuNC open the B-B bond of 1; the resulting five-membered ring 7a may add excess tBuNC to yield 7a · 2 CNtBu (8). The results strongly support a mechanistic hypothesis set up for the multistep reaction of 1 and CO. The carbene units, which are present in the α-bromolithioalkanes [-C(Br)Li-CMe2-CH2-], LiC(Br)H2, and LiC(Br)Me2, are also 1,1-boroborated by 1 to give the corresponding four-membered ring 2c, or by a 2:1 reaction to afford the five-membered ring 7b, or by a 1:1 reaction and subsequent rearrangement to yield the five-membered ring 7c. The nitrene units, which are present in the azides PhN3 and PhCH2N3, are also boroborated by 1; the diazadiboretidines 5b, c are formed with evolution of N2. The bis(diazadiboretidinyl)borane RB(N2B2R3)2 (5d) is the corresponding product from the reaction of RB(N3)2 with 1 in the ratio 1:2. The azide Me3SiN3 reacts differently yielding the N-boryl diazadiboretidine 5e and the iminoborane RB≡N̊. The B-B bond length of 187.6 pm in 5e indicates a transannular bonding interaction. The products 5d, 5e, and 6a were characterized by a crystal structure analysis.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19951281011
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  • 5
    Electronic Resource
    Electronic Resource
    Thiaaza-arachno-pentaboran SNB3H2tBu3R (1995)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 128 (1995), S. 1105-1108 
    Details
    ISSN: 0009-2940
    Keywords: Azadiboriridine, tri-tert-butyl- ; Mercaptoborane ; Thiaaza-arachno-pentaborane, 1,4,5-tri-tert-butyl-2-organo- ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Thiaaza-arachno-pentaborane SNB3H2tBu3RThe azadiboriridine [-B(tBu)-N(tBu)-B(tBu)-] (1) gives 1:1 adducts with the mercaptoboranes BH2(SR), which can be generated from their cyclotrimers by the action of THF. The adduct 4a (R = Ph), a nido cluster with an NB3 skeleton, forms an equilibrium with an adduct 5a, an arachno cluster with an SNB3 skeleton, whose S-bound ligand Ph is found in an endo position by an X-ray structural analysis. The equilibrium 4a · 5a involves a Lewis acid-base reaction, which is electronically coupled to a reduction of a three-center to give a two-center π bond. The reaction of 1 with BH2(SPr) gives the corresponding arachno cluster 5b only.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19951281108
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  • 6
    Electronic Resource
    Electronic Resource
    Electrophilic Substitution at the NB9 and NB11 closo-SkeletonsDedicated to Professor Kurt Dehnicke on the occasion of his 65th birthday (1996)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996), S. 1227-1231 
    Details
    ISSN: 0009-2940
    Keywords: Aza-closo-decaboranes, halogenation of, methylation of ; Aza-closo-dodecaboranes, halogenation of, methylation of ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The aza-closo-boranes ArNB9H9 (1, Ar = p-ClC6H4) and MeNB11H11 (2) were brominated, iodinated, or methylated under Friedel-Crafts conditions to give ArNB9H4Br5 (3), ArNB9H7I2 (4), ArNB9H4Me5 (7), MeNB11H10Br (5), MeNB11H10I (6), and MeNB11H5Me6 (9), respectively. The upper boron belt adjacent to nitrogen is not involved in the substitution reactions with 1 and 2. The antipodal position and the lower belt are attacked by electrophiles in the case of 1; the antipodal position is the preferred one in the case of 2. By prolongated action of triflic acid on the methylated species 7 and 9, one methyl group is replaced by the triflate group to give ArNB9H4Me4(OTrf) (8) and MeNB11H5Me5-(OTrf) (10) with this group in the positions 6 and 12, respectively. The NMR data indicate the cluster symmetries Cs (4, 8), C4v (3, 7), and C5v (5, 6, 9, 10). Crystal structure investigations of 5 (space group Cc) and 10 (space group C2/c) showed that the molecular dimensions of the NB11 skeleton are comparable to those of closo, -(PhCH2)NB11H11.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19961291014
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  • 7
    Electronic Resource
    Electronic Resource
    1,1-Hydroborierung von Alkinen mit 6-Aza-nido-decaboranen (1995)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 128 (1995), S. 947-951 
    Details
    ISSN: 0009-2940
    Keywords: 6-Aza-nido-decaborane ; 9-(1-Alkenyl)-6-phenyl-6-aza-nido-decaborane ; 1,1-Hydroboration of alkynes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1,1-Hydroboration of Alkynes with 6-Aza-nido-decaboranes[1]Alkynes AC≡CR′ (R′ = Me, Bu, tBu, SiMe3), that contain a mobile group A, like H or SiMe3, undergo hydroboration by 6-aza-nido-decaboranes RNB9H11 (1a-c, R = H, Ph, PhCH2) and 1,2-migration of the group A, to give the corresponding 9-(1-alkenyl)-6-aza-nido-decaboranes RNB9H10(CH=CR′A) (2a-h). Ethenes AHC=CH2 (A = SiMe3, SnBu3) are hydroborated by 1a, b as well to form products of the type RNB9H10(CH2CH2A) (3a-c). The alkyne Me3SiC=CH undergoes a hydroboration with 1b twice; the formation of (PhNB9H10)2CHCH2SiMe3 (4) proceeds by a 1,1- and a 1,2-hydroboration step, apparently. The crystal structure analysis of (PhCH2)NB9H10[CH=CMe(SiMe3)] (2e; space group Pl) reveals a (Z configuration of the ethene moiety.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19951280916
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  • 8
    Electronic Resource
    Electronic Resource
    Polare Iminoborane: Reaktionen des (tert-Butylimino)(pentafluorphenyl)borans (1995)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 128 (1995), S. 1037-1043 
    Details
    ISSN: 0009-2940
    Keywords: Iminoborane ; Triazadiboracyclohexane ; Borazine ; Diazadiboracyclobutane ; Azaboracyclobutane ; Diazadiboracyclopentane ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Polar Iminoboranes: Reactions of (tert-Butylimino)(pentafluorophenyl)boraneThe reactions of the iminoborane C6F5-B≡N-tBu (1) with nitriles and isonitriles are studied. Nitriles RCN give cycloadducts either of the triazadiboracyclohexane type (3a; R = iPr) or of the tetrazatriborabicyclo[4.2.0]octane type [4b-d; R = Ph, p-C6H4Me, p-C6H4(CF3)] or of the (iminomethyl)borazine type (5e, f; R = Me, Et). Isonitriles RNC yield mainly adducts of RNC to a cycloaddition product of the diazadiboracyclopentane type (6a, b; R = 2,6-C6H3Me2, tBu); the adduct of RNC to a diazadiboracyclobutane may be a side-product (7b; R = tBu). The iminoborane Me3Si(tBu)N-B=NtBu reacts with two molecules of (2,6-C6H3Me2)NC to give the corresponding azaboracyclobutane 8. The iminoborane tBu-B≡N-C6F5 (1′), formed by gas-phase elimination of ClSiMe3 from Cl(tBu)B = N(C6F5)SiMe3 (9), cyclodimerizes more readily than the isomeric borane 1. The cyclodimer 2′ gives 1:1-addition reactions with tBuNC, PMe3, and MeNC, respectively; the added components fluctuate in solutions of the products 7b'-d'. A similar fluctuation is observed with the 1:1 adduct 7c from PMe3 and the cyclodimer 2 of the iminoborane 1. The products 3a, 5e, 6a, 8 crystallize in the space groups P21/c, P21/n, Pbca, and P21/c, respectively.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19951281012
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  • 9
    Electronic Resource
    Electronic Resource
    Öffnung des Aza-closo-dodecaboran-Gerüsts durch Basen (1995)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 128 (1995), S. 1225-1229 
    Details
    ISSN: 0009-2940
    Keywords: 1-Organo-1-aza-closo-dodecaborane(12) ; Trialkylamine-1-organo-1-aza-nido-dodecaborane(12) (1/1) ; Undecahydro-1-organo-1-aza-nido-dodecaborate(1-), 2-hydro-, 2-halogeno-, 2-alkoxy-, 2-amino-, 2-alkyl- ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Opening of the Aza-clso-dodecaborane Skeleton by BasesThe aza-closo-borane PhNB11H11 (1a) is opened by the amines NR3 (R = Me, Et) to give the novel aza-nido-dodecaboranes PhNB11H11(NR3) (2a, b). The non-planar open pentagonal face of 2a, b accomodates the N atom, a BHB bridge, and the base-bound B atom, according to NMR spectra and the crystal structure analysis of monoclinic 2b. A similar but more symmetric structure is found when closo-RNB11H11 (1a-c, R = Ph, Me, H) is attacked by anionic bases X- to give nido-RNB11H11X- (3a-j; R/X = Me/H, Me/F, Me/Cl, Ph/OH, H/OMe, Me/OMe, Me/OtBu, Me/NEt2, Me/Me, Me/Bu). The anions are precipitated with cations [K([18]crown-6)], [S(NMe2)3], [N(PPh3)2], [Et2NH2], or [Li(tmeda)2]. The nido-structures of type 2 and 3 are derived from the hypothetical closo-NB12H13.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19951281214
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  • 10
    Electronic Resource
    Electronic Resource
    (Iminoboryl)borate [R3B—B≡NR]-: Durch Elektrophile E induzierte Umlagerung zu (Aminoboryl)boranen R2B—BR=NRE (1996)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996), S. 361-365 
    Details
    ISSN: 0009-2940
    Keywords: (Iminoboryl)borates ; (Aminoboryl)boranes ; Trialkyl(amino)diboranes(4) ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: (Iminoboryl)borates [R3B—B=NR]-: Rearrangement to (Aminoboryl)boranes R2B—BR=NRE by the Addition of Electrophiles E(Iminoboryl)borates [Li(tmeda)2][R2R′B-B≡NR (2a-c, R′ = Me, Me3SiCH2, Me3CCH2) are formed from the azadiboriridine NB2R3 (1, R = tBu) and LiR′ in the presence of tmeda. Vinyllithium brings about a ring expansion of 1 to give the five-membered anionic ring [-CH=CH-BR=NR-BHR-]-, to which [Li(tmeda)]+ is bound (3). The (aminoboryl)boranes R2B-BMe=NER (4a-c, EX = HCl, MeI, Me3SiI) are obtained, when the polar compounds EX are added to 2a, accompanied by the elimination of LiX and the migration of Me. The borate 2b reacts with HCl to give a mixture of the isomers R2B-B(CH2SiMe3)=NHR (4d) and R(Me3SiCH2)-B-BR=NHR (4d′), and 2c reacts with HCl to yield the borane R(Me3CCH2)B-BR=NHR (4e′) exclusively. The transformation of [R2R′B-B=NR]- to R2B-BR′ = NRE by the attack of electrophiles E corresponds to the known transformation of [R′3B-C≡R″] to R′2B-CR′=CR″E.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19961290318
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