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  • 1
    Electronic Resource
    Electronic Resource
    Synthesen neuer bororganischer Ringe mit zwei Bor-Atomen durch Borylierung des Trimethylenmethan-Dianions (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 23-29 
    Details
    ISSN: 0009-2940
    Keywords: Diboracycloalkanes ; Diboracycloalkenes ; Trimethylenemethane, borylation of the dianion of ; Allylboranes, B - C bond length ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Syntheses of New Organoboron Rings with two Boron Atoms by Borylation of the Trimethylenemethane DianionBorylation of Li2[C(CH2)3] (1) provides a versatile starting point for the synthesis of 5-, 6-, 7-, and 8-membered ring systems with two boron atoms and leads to 1,5-bis(dialkylamino)-3,7-dimethylene-1,5-diboracyclooctanes 2a, b (a: R=Et; b: R=iPr), 1,3-bis(dialkylamino)-5-methylene-1,3-diboracyclohexanes 8a, b, 1,3-bis(diethylamino)-5-methyl-1,3-dibora-4-cyclo-hexene (10), and 1,4-bis(dialkylamino)-6-methylene-1,4-dibora-2-cycloheptenes 11a, b. The compounds 2b, 8b, and the 2,3-biboratafulvene derivative [Li(TMEDA)]2[CH2C(CHB)2-(NiPr2)2] are characterized by X-ray diffraction analysis. It is shown that for trigonal boron B - C(allyl) bond distances (typically 160 ± 1 pm) are significantly larger than B - C(alkyl) distances (typically 158 + 1 pm).
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921250105
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  • 2
    Electronic Resource
    Electronic Resource
    Elektronenüberschuß-Komplexe von Cobalt und Nickel mit Cyclobutadien-Liganden: Synthese, Cyclovoltammetrie und Reaktivität (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 1589-1595 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Electron-Excess Complexes of Cobalt and Nickel with Cyclobutadiene Ligands: Syntheses, Cyclovoltammetry, and Reactivity[1]A cyclovoltammetric investigation of tetraphenylcyclobutadiene complexes [ML(C4Ph4)]+ [1: ML = NiCp; 2a: ML = Co(C6H6); 2b: ML = Co(mesitylene)] reveals a reversible reduction to paramagnetic complexes 1 and 2a,b with a 19-electron count, and a subsequent irreversible reduction to anions 1- and 2a,b- with a 20-electron shell. Preparative reduction by one equivalent of CpFe(HMB) (HMB = C6Me6) produces the novel 19-electron complexes 1 and 2b. Complex 1 can also be obtained by treatment of 1 · Br with one equivalent of CoCp2 at room temperature while reduction at -20°C with two equivalents of CoCp2 affords a novel C-C-linked adduct CpNi[μ,η3:η4-(C4Ph4-C5H5)]CoCp (5). Above -10°C a slow equilibrium between 5 and its components 1 and CoCp2 is observed with ΔH = 15 kJ/mol for the dissociation process. With an excess of the stronger reductant sodium amalgam the cations 1+ and 2a+ are reduced to give cyclobutenyl complexes ML(η3-1,2,3,endo-4-C4HPh4) [6: ML = NiCp; 7: ML = Co(C6H6)]. 1 reacts with p-nitrobenzyl bromide to give 1 Br and a p-nitrobenzyl addition product CpNi[η3-exo-4-(p-O2NC6H4CH2)-1,2,3,endo-4-C4Ph4] (11) while 2b reacts with MeI to give 2b · I and two isomeric methyl addition products (η5-1,3,5,exo-6-C6H3Me4)Co(C4Ph4)] (12) and (mes)Co(η3-exo-4-Me-1,2,3,endo-4-C4Ph4) (13). Sodium-amalgam reduction of the tetramethylcyclobutadiene cations [(arene)Co(C4Me4)]+ (4a: arene = C6H6; 4b: arene = mesitylene) affords diamagnetic dinuclear compounds of type 8-10 with C-C linkages between C4Me4/C4Me4, arene/C4Me4, and arene/arene rings, respectively.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921250713
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  • 3
    Electronic Resource
    Electronic Resource
    Derivate des Borols, XVIII. Tricarbonyl[η5-(1-phenylborol)]eisen: Zur Reaktivität der koordinierten Liganden (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 1801-1805 
    Details
    ISSN: 0009-2940
    Keywords: (Borole)carbonyliron derivatives, electrophilic substitution, nucleophilic addition, reduction ; Iron complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Derivatives of Borole, XVIII. - Tricarbonyl[η5-(1-phenylborole)]iron: Reactivity of the Coordinated LigandsThe borole complex (C4H4BPh)Fe(CO)3 (1) undergoes Friedel-Crafts acetylation (MeCOCl/AlCl3) at the meta-position of the phenyl substituent while the derivatives (C4H4BPh)Fe(CO)2L (3, a: L = NMe3′ b: L = PMe3) are acetylated at the 2-position of the borole ring. Organolithium reagents (LiMe, LiBu) add to 1 at the boron atom below - 50°C while nucleophilic attack at the carbonyl C atom takes place at higher temperature with formation of acyl anions [(C4H4BPh)Fe(CO)2(COR)]- (6a,b-). The Fischer carbene complex (C4H4BPh)Fe(CO)2[C(OMe)Me] (7) is obtained from 6a-/[Me3O]BF4. Complex 1 reacts with LiN(SiMe3)2 to give [(C4H4BPh)Fe(CO)2(CN)]- (8-) and with 5 M NaOH/C6H6/NBu4HSO4 to produce the hydride NBu4-[(C4H4BPh)FeH(CO)2] (NBu4 · 9). A highly reactive dianion [(C4H4BPh)Fe(CO)2]2- (102-) is obtained by deprotonation of 9- or by reduction of 1 or 3a in THF at -70°C. Treatment of 102- with Ph3SnCl gives [(C4H4BPh)Fe(CO)2(SnPh3)]- (11-) which is isolated as NEt4 · 11. Slow reduction of 3a with sodium amalgam in THF at -30°C produces doubly CO-bridged cis-[{(C4H4BPh)Fe(CO)2}2]2- (122-) which is protonated to the μ2-hydrido anion [μ-H-{(C4H4BPh)Fe(CO)2}2]- (13-).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921250804
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  • 4
    Electronic Resource
    Electronic Resource
    Derivate des Borols, XIX. (Borol)dicarbonylcobaltat-Ionen: Synthese, Struktur und Reaktivität (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 2351-2357 
    Details
    ISSN: 0009-2940
    Keywords: (Borole)dicarbonylcobalt anions, methylation, protonation ; (Boracyclopentenyl)dicarbonyl(phosphane)cobalt complexes, hydride abstraction ; (Borole)dicarbonyl(phosphane)cobalt cation, hydride addition ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Derivatives of Borole, XIX[1]. - (Borole)dicarbonylcobaltate Ions: Synthesis, Structure, and Reactivity[3]Reduction of the dinuclear (borole)carbonylcobalt complexes [(3,4-R2C4H2BPh)Co(CO)2]2 (3a: R = H, b: R = Me) with Na/Hg in THF at -30°C affords the anions [(3,4-R2C4H2BPh)-Co(CO)2]- (2a,b-) which can be isolated as [Na([15]crown-5)]+ salts. The structural data of PPh4 · 2a indicate a strong Co - C(CO) interaction and relatively weak cobalt-to-boron bonding. Methylation of the anions 2a,b- gives labile metal alkyl complexes (3,4-R2C4H2BPh)Co(CO)2Me while protonation and subsequent addition of phosphanes afford boracyclopentenyl complexes as e.g. (C4H5BPh)Co(CO)2(PMe3) (5a). The latter reacts with Ph3CBF4 to give the salt [(C4H4BPh)Co(CO)2-(PMe3)]BF4 (6 · BF4). At -80CC cation 6+ undergoes hydride addition at the carbonyl carbon to give the formyl species (C4H4BPh)Co(CO)(CHO)(PMe3) (7) which transforms to the hydride (C4H4BPh)CoH(CO)(PMe3) (8). At room temperature the same reaction produces 5a. Deuteration studies show that the oxidative formation of 6+ from 5a and the formation of 5a by addition of hydride to 6+ are nonstereospecific processes.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921251104
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