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  • 2015-2019
  • 1985-1989  (51)
  • Chemistry  (49)
  • Interchange heterozygotes  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 70 (1985), S. 213-221 
    ISSN: 1432-2242
    Keywords: Chromosome numbers ; Karyotype evolution ; Interchange heterozygotes ; Multivalent segregation ; Vicia faba ; Pseudoaneuploidy ; Robertsonian exchanges
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A new mechanism for changing chromosome numbers (preserving the fundamental number of long chromosome arms) during karyotype evolution is suggested. It includes: 1) Occurrence of individuals heterozygous for two interchanges between different arms of three chromosomes (a metacentric and two acrocentric ones). 2) Formation in heterokaryotypes of multivalents during meiosis between the chromosomes involved in the interchanges and their unchanged homologues. 3) Mis-segregation of chromosomes from these multivalents resulting in hypoploid (n-1) and hyperploid (n+1) simultaneously instead of euhaploid gametes. 4) Fusion of n-1 or n+1 gametes which gives rise to (zygotes and) individuals representing homokaryotypes with changed number of chromosomes (2n+2 or 2n-2), but preserves (as compared to the parental karyotypes) the number of long chromosome arms. Under definite conditions, chromosome numbers of the progeny may be changed by this process in both directions (upwards and downwards). The mechanism is free of the difficulties associated with the explanation for such changes by direct Robertsonian interchanges (see “Discussion”), which are usually considered to be responsible for such alterations in chromosome number. The above-mentioned process has been experimentally documented in Vicia faba and it probably also occurred naturally within the Vicia sativa group.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 76 (1988), S. 64-70 
    ISSN: 1432-2242
    Keywords: Vicia faba ; Duplication ; Deletion ; Interchange heterozygotes ; Pseudoaneuploidy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary From eight pairs of crosses between differently reconstructed diploid karyotypes of Vicia faba, the progeny after selfing of plants heterozygous for both parental chromosome reconstructions were inspected for occurrence and transmission of duplications and deletions of defined chromosome segments, comprising together about one third of the metaphase genome length. The duplications and deletions studied involved either one or more chromosome segments of the respective karyotype (0.8%–9.1% of the metaphase length). They arose during meiosis in double heterozygotes by crossing over between partially homologous chromosomes or by mis-segregation from multivalents. While most duplications, provided they were not accompanied by deletions and in dependence on the segment involved, were viable and transmissible, even in homozygous state, deletions had lethal effects on gametes of both sexes.
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 120 (1987), S. 879-887 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Complexes [mer-(CO)3Fe(H)SiR3]2(dppe) (1) (dppe=Ph2PCH2-CH2PPh2), [mer-(CO)3Fe(SiR3)2]2(dppe) (2), (CO)2(dppe)Fe(H)-Sir3 (3), and (CO)2(dppe)Fe(SiR3)2 (6) are synthetized by several routes: by photochemical reaction of dppe-substituted iron carbonyls with HSiR3, by thermal reaction of (CO)4Fe(H)SiR3 or (CO)4Fe(SiR3)2 with dppe, or by exchange of the silyl groups. The dinuclear complexes 1 and 2 can be converted to the mononuclear complexes 3 and 6. The choice of the most suitable method of preparation depends essentially on the nature of the silyl ligand. Bissilyl complexes (2 or 6) are only obtained if SiR3=SiCl3 or SiMeCl2. In solution the complexes 3 are fluxional. In the crystalline state 3d (SiR3=SiMe3) shows a distorted octahedral geometry. The silyl group has trans orientation to one of the phosphorus atoms and cis to the hydride ligand, which in turn is trans to one of the carbonyls.
    Notes: Komplexe [mer-(CO)3Fe(H)SiR3]2(dppe) (1) (dppe=Ph2PCH2CH2PPh2), [mer-(CO)3Fe(SiR3)2]2(dppe) (2), (CO)2(dppe)Fe(H)-SiR3 (3) und (CO)2(dppe)Fe(SiR3)2 (6) können nach mehreren Methoden synthetisiert werden: durch photochemische Umsetzung von dppe-substituierten Eisencarbonylen mit HSiR3, durch thermische Umsetzung von (CO)4Fe(H)SiR3 oder (CO)4Fe(SiR3)2 mit dppe oder durch Silylgruppenaustausch. Die zweikernigen Komplexe 1 und 2 lassen sich in die einkernigen Komplexe 3 und 6 umwandeln. Die Wahl der jeweils günstigsten Darstellungsmethode hängt entscheidend von der Art des Silylrestes ab. Bissilyl-Komplexe (2 oder 6) werden nur mit SiR3=SiCl3 oder SiMeCl2 erhalten. Die Komplexe 3 sind in Lösung fluktuierend. Im kristallinen Zustand ist 3d (SiR3=SiMe3) verzerrt oktaedrisch koordiniert, der SiMe3-Rest steht trans zu einem der Phosphoratome und cis zum Hydrid-Liganden, welcher seinerseits trans zu einem der Carbonyle angeordnet ist.
    Additional Material: 2 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 223-230 
    ISSN: 0009-2940
    Keywords: Gold(I) silyl complexes ; Transition-metal silyl complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Transition-Metal Silyl Complexes, 26. - Gold(I) Silyl ComplexesComplexes of type L-Au-SiR3 with L = PR′3 or PhNC and SiR3 = Si(aryl)3, Si(SiMe3)3, or SiPh2Me are prepared by reaction of L-Au-Cl with LiSiR3. Depending on L and R, their stability decreases, in the order R′3P-Au-Si(aryl)3 〉 R′3P-Au-Si(SiMe3)3 〉 R′3P-Au-SiPh2Me ≈ PhNC-Au-SiR3. Reaction of R′3P-Au-CH3 or R′3P-Au-OAc with HSiR3 does not yield silyl complexes. However, using chlorinated silanes like HSiR2Cl, CH3/Cl or OAc/Cl exchange takes place. The Mössbauer spectrum of MePh2P-Au-SiPh3 (6) and NMR- and IR-spectroscopic investigations show that silyl groups act as strong σ donors towards the gold atom. MePh2P-Au-SiPh3 (6) and MePh2P-Au-Si(SiMe3)3 (7) have been characterized by X-ray structure analyses [Au—Si 235.4(4) and 235.6(2) pm]. The Au-Si bond in MePh2P-Au-SiPh2Tol (5) is cleaved by X2 (X = Cl, Br, I), HCl or MeI, but not by H2O or MeOH.
    Notes: Komplexe des Typs L-Au-SiR3 mit L = PR′3 oder PhNC und SiR3 = Si(aryl)3, Si(SiMe3)3 oder SiPh2Me wurden durch Umsetzung von L-Au-Cl mit LiSiR3 dargestellt. Ihre Stabilität sinkt in Abhängigkeit von L und R in der Reihenfolge R′3P-Au-Si(aryl)3 〉 R′3P-Au-Si(SiMe3)3 〉 R′3P-Au-SiPh2Me ≈ PhNC-Au-SiR3. Umsetzung von R′3P-Au-CH3 oder R′3P-Au-OAc mit HSiR3 ergibt keine Silyl-Komplexe, bei Verwendung chlorierter Silane, HSi-R2Cl, findet lediglich CH3/Cl- bzw. OAc/Cl-Austausch statt. Das Mößbauer-Spektrum von MePh2P-Au-SiPh3 (6) sowie NMR- und IR-spektroskopische Untersuchungen zeigen, daß Silylreste als starke σ-Donor-Liganden gegenüber dem Goldatom wirken. MePh2P-Au-SiPh3 (6) und MePh2P-Au-Si(SiMe3)3 (7) wurden durch Röntgenstrukturanalysen charakterisiert [Au—Si 235.4(4) und 235.6(2) pm]. Die Au—Si-Bindung in MePh2P-Au-SiPh2 Tol (5) wird durch X2 (X = Cl, Br, I), HCl oder MeI, nicht aber durch H2O oder MeOH gespalten.
    Additional Material: 2 Ill.
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  • 5
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Complexes with Carbon Sulfides and Selenides as Ligands, XIV. Cobalt and Rhodium Complexes Containing an η2-(C,S) Coordinated Thioketene. The Crystal Structure of The complexes C5H5Co(L)PMe3 (1) and C5H5Rh(L)PMe3 (2) are obtained on reaction of 1,1,3,3-tetramethyl-2-(thiocarbonyl)cyclohexane (L) with C5H5Co(PMe3)2 and C5H5Rh(C2H4)-PMe3, respectively. The crystal structure of 1 shows that the thioketene is linked via S and C (η2) to the metal. The Co — S and Co — C distances indicate the L is a somewhat weaker π-acceptor ligand than CS2. 1 reacts with CH3I by addition of the methyl group to the sulfur atom of the CoSC three-membered ring to form (3).
    Notes: Die Komplexe C5H5Co(L)PMe3 (1) und C5H5Rh(L)PMe3 (2) entstehen bei der Reaktion von 1,1,3,3,-Tetramethyl-2-(thiocarbonyl)cyclohexan (L) mit C5H5Co(PMe3)2 bzw. C5H5Rh(C2H4)-PMe3. Die Kristallstruktur von 1 zeigt, daß das Thioketen über S und C (η2) an das Metall gebunden ist. Die Co — S— und Co — C-Abstände deuten an, daß L ein etwas schwächerer π-Akzeptorligand als CS2 ist. 1 reagiert mit CH3I unter Addition der Methylgruppe am Schwefelatom des CoSC-Dreirings und Bildung von (3).
    Additional Material: 1 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 119 (1986), S. 2900-2903 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Silicon-Containing Carbene Complexes, VII. Disulfide- catalyzed Reaction of (CO)5WC(XR)SiPh3 (X = O, S) with Thiols(CO)5WC(OEt)SiPh3 (1) reacts with RSH (R = Et, Me) only in the presence of disulfide, R2S2, to yield (CO)5WC(SR)SiPh3 (2). Supplementary experiments indicate a cyclic transition state (A) which is formed from carbene complex, thiol, and disulfide. Exchange of the alkylthio group of 2 proceeds by an analogous mechanism.
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  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 121 (1988), S. 939-941 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Transition-metal Silyl Complexes, 23.  -  Experiments on the mechanism of the Formation of [C5H4Si(SiMe3)3]2WH2 from (C5H5)2 and Li[Si(SiMe3)3]Silyl complexes, which are formed as intermediates in the reaction of Cp2WCl2 with Li[Si(SiMe3)3] (1), spontaneously rearrange to give tungstenocene hydride derivatives. Partial steps of the formation of [C5H4Si(SiMe3)3]2 WH2 (2) can be performed individually: The silyl complex Cp2W(H)Si(SiMe3)3, which is obtained from and Cp2W(H)Cl 1, reacts with methyl iodide by rearrangement to give the ring-substituted derivative Cp[C5H4Si(SiMe3)3]W(H)I (4), which yields 2 on reaction with 1. Since 3 is not deprotonated by 1, base-induced rearrangements can be excluded.
    Notes: Bei der Umsetzung von Cp2WCl2 mit Li[Si(SiMe3)3] (1) intermediär entstehende Silyl-Komplexe lagern sich spontan zu Wolframocenhydrid-Derivaten um. Teilschritte der Bildung von [C5H4Si(SiMe3)3]2 WH2 (2) können einzeln durchgeführt werden: Der aus Cp2W(H)Cl und 1 erhältliche Silyl-Komplex Cp2W(H)Si(SiMe3)3 (3) reagiert mit Methyliodid unter Umlagerung zum ringsubstituierten Derivat Cp[C5H4Si(SiMe3)3]W(H)I (4), welches mit 1 den Dihydrid-Komplex 2 ergibt. Da 3 durch 1 nicht deprotoniert wird, können baseinduzierte Umlagerungen ausgeschlossen werden.
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  • 8
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Transition-Metal Silyl complexes, 27. Silyl-Substituted Heteromultinuclear Complexes by Reaction of the Anionic Silyl Complexes [MeCpMn(CO)2SiR3]- and [Fe(CO)3(PPh3)SiR3]- with Dihalides of Zinc, Cadmium, or MercuryThe anionic silyl complexes [MeCpMn(CO)2SiMePh2]- (1) and [Fe(CO)3(PPh3)SiR3]- (4) react with equimolar amounts of ZnCl2, CdCl2, or HgBr2 to give the dinuclear complexes MeCpMn(CO)2(SiMePh2)MX (2; MX = ZnCl, CdCl, or HgBr) or Fe(CO)3(PPh3)MX (5; MX = CdCl or HgBr); the Fe—Zn complex is unstable. Reaction of 2 and 5 with a second equivalent of 1 or 4 yields the symmetrical trinuclear complexes [MeCpMn(CO)2(SiMePh2)]2M (3; M = Cd, Hg) and [Fe(CO)3(PPh3)(SiR3)]2Hg (6) or the unsymmetrical trinuclear complex MeCp(CO)2(Ph2MeSi)Mn—Hg—Fe(CO)3 (PPh3)(SiR3) (7). The symmetrical complexes containing Mn—Zn—Mn or Fe—Cd—Fe units are not formed, presumably for steric reasons. With an excess of mercury halides 3 (M = Hg) and 6 react by silyl halide elimination.
    Notes: Die anionischen Silyl-Komplexe [MeCpMn(CO)2SiMePh2]- (1) und [Fe(CO)3(PPh3)SiR3]- (4) reagieren mit äquimolaren Mengen ZnCl2, CdCl2 oder HgBr2 zu den Zweikern-Komplexen MeCpMn(CO)2(SiMePh2)MX (2; MX = ZnCl, CdCl oder HgBr) bzw. Fe(CO)3(PPh3)(SiR3)MX (5; MX = CdCl oder HgBr); der Fe—Zn-Komplex ist instabil. Umsetzung der Komplexe 2 und 5 mit einem weiteren Äquivalent 1 bzw. 4 ergibt die symmetrischen Dreikern-Komplexe [MeCpMn(CO)2(SiMePh2)]2M (3; M = Cd, Hg) und [Fe(CO)3(PPh3)]2Hg (6) bzw. den unsymmetrischen Dreikern-Komplex MeCp(CO)2(Ph2MeSi)Mn—Hg—Fe(CO)3-(PPh3)(SiR3) (7). Die symmetrischen Komplexe mit Mn—Zn—Mn- bzw. Fe—Cd—Fe-Bindung werden vermutlich aus sterischen Gründen nicht gebildet. Mit überschüssigem Quecksilberhalogenid reagieren 3 (M = Hg) und 6 unter Halogensilan-Abspaltung.
    Additional Material: 1 Tab.
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  • 9
    ISSN: 0009-2940
    Keywords: Anionic metal complexes ; Chlorosilane elimination ; Phosphinidene complexes ; Silyl complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Transition-Metal Silyl Complexes, 32.  -  Anionic Silyl Complexes as Equivalents to Dianionic Metal Complexes in Synthesis: Reactions of [(MeCp)(CO)2Mn(SiR3)]⊖ with Main-Group 5 DihalidesThe versatility of anionic silyl complexes for preparative purposes is demonstrated by reactions with dihalides of phosphorus, arsenic, and antimony in their +III and +V oxidation states. Na[(MeCp)(CO)2Mn(SiMePh2)] (1) reacts with Ph3AsCl2 or Ph3SbBr2 to give (MeCp)(CO)2Mn(EPh3) (2a: E = Sb, 2b: E = As), while reaction with MesPCl2 (Mes = 2,4,6-Me3C6H2) affords the binuclear compound [(MeCp)(CO)2Mn]2PMes (3). Both reactions proceed by Ph2MeSiX elimination.
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  • 10
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Cycloaddition Reactions of Organometal Complexes, III. Five-membered Metalla-Heterocycles by [3 + 2] Cycloaddition of a Imidoylcobalt Unit and a Carbonyl Compound: Syntheses, Structure, and ReactivityThe reaction of [C5H5CoCH3(CNCH3)PMe3]I with carbonyl compounds RR′C = O (R = R′ = CH3; R = H, R′ = CH3, C6H5) leads to the metalla-heterocycles (1-3) which are isolated as the iodide or PF6 salts. The X-ray structure analysis of the monohydrate of 1a (R = R′ = CH3; X = I) shows that the structural characteristics of the two parts (acetimidoyl ligand and acetone) forming the CoCNCO ring are partially preserved. The CoCNC part of the five-membered ring is nearly planar whereas the oxygen atom lies 34 pm out of this plane pointing towards the phosphane ligand. The protonation and methylation reactions of 1a and 2 (R = H, R′ = CH3; X = PF6) yield dicationic cyclic (aminocarbene)cobalt(III) complexes which in some cases react with excess of acid by ring cleavage and elimination of RR′C = O. In the reactions of 1b (X = PF6), [C5H5Co(η2-C(CH3)N-t-C4 H9)PMe3]I, and [C5H5Co(η1-C(CH3)NC6H 5)I] with PMe3 (and NH4PF6) the η1-imidoylcobalt(III) complexes [C5H5Co(η1-C(CH3)NR)(PMe3)2]PF6 (12-14) are formed, from which on protonation the (aminocarbene)cobalt(III) compounds [C5H5Co(C(CH3)NHR)(PMe3)2](PF 6)2 (15-17) are obtained.
    Notes: Die Reaktion von [C5H5CoCH3(CNCH3)PMe3]I mit den Carbonylverbindungen RR′C = O (R = R′ = CH3; R = H, R′ = CH3, C6H5) führt zu den Metalla-Heterocyclen (1-3), die in Form der Iodide oder PF6-Salze isoliert werden. Die Röntgenstrukturanalyse des Monohydrats von 1a (R = R′ = CH3; X = I) zeigt, daß die den CoCNCO-Fünfring bildenden Gruppen, Acetimidoyl-Ligand und Aceton, ihre strukturellen Charakteristika teilweise noch bewahrt haben. Die CoCNC-Einheit des Rings ist fast planar, während das Sauerstoffatom 34 pm außerhalb dieser Ebene auf der dem Phosphanliganden zugewandten seite liegt. Die Protonierungs- und Methylierungsreaktionen von 1a und 2 (R = H, R′ = CH3; X = PF6) ergeben dikationische cyclische (Aminocarben)cobalt(III)-Komplexe, die teilweise mit Überschuß an Säure unter Ringspaltung (und Eliminierung von RR′C = O) reagieren. Bei den Umsetzungen von 1b (X = PF6), [C5H5Co(η2-C(CH3)N-t-C4H 9)PMe3]I und [C5H5Co-(η1-C(CH3)NC6H5)PMe3)I] mit PMe3 (und NH4PF6) entstehen die η1-Imidoylcobalt(III)-Komplexe [C5H5Co(η1-C(CH3)NR)(PMe3) 2]PF6 (12-14), aus denen durch Protonierung die (Aminocarben)cobalt(III)-Verbindungen [C5H5Co(C(CH3)NHR)(PMe3)2] (PF6)2 (15-17) erhältlich sind.
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