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  • 1
    Electronic Resource
    Electronic Resource
    1,3-Heterobinuclear Cyclobutenylidene Complexes with an Exocyclic C=C bond  -  Synthesis, Structure, and Spectroscopic Properties (1996)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996), S. 1475-1482 
    Details
    ISSN: 0009-2940
    Keywords: Allenylidene complexes ; Alkynyl complexes ; Cyclobutenylidene complexes ; Cycloadditions ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Pentacarbonyl(allenylidene)chromium and -tungsten, [(CO)5—M=C=C=CR2] (M=Cr, R=C6H4CH3-p(1a), C6H4OCH3 (1b); M=W, R=C6H4CH3-p (1c), react with the alkynyl complexes [Cp(CO)2Fe—C≡CR′] (R′ = nBu (2), Ph (4)), [Cp*(CO)2Fe—C≡CnBu] (6), [Cp(CO){P(OMe)3}-Fe—C≡CnBu] (8) and [Cp(PPh3)Ni—C≡CnBu] (10) by cycloaddition of the C≡C bond of the alkynyl complexes to the Cα=Cβ bond of the allenylidene ligand to give 3a-c), (5), (7), and respectively. The cycloaddition is highly selective. The spectroscopic data of these 1,3-heterobinuclear complexes indicate a delocalized π-system (M=Cr, W; Y=[Fe(CO)2Cp], [Fe(CO)(P{OMe}3)Cp], [Fe(CO)2Cp*], [Ni(PPh3)-Cp]). X-ray structural analyses of the compounds 3a, 9a, and 11c reveal a “butterfly” conformation of the four-membered ring. Its puckering angle is 142° (3a), 152° (9a), and 151° (11c). All Complexes exhibit a moderate to strong negative solvatochromic behavior. The extent of the solvatochromic effect depends on [(CO)5M] and Y and considerably decreases when C=CR2 is replaced by e.g. CMe2.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19961291212
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  • 2
    Electronic Resource
    Electronic Resource
    Donorsubstituierte Cyclobutenyliden-Komplexe und Cyclobutenone aus Vinyliden-Komplexen und elektronenreichen Alkinen (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 2667-2673 
    Details
    ISSN: 0009-2940
    Keywords: Vinylidene complexes ; Cyclobutenylidene complexes ; Cyclobutenone ; Cyanamide complexes ; Butatriene, tetraphenyl- ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Donor-Substituted Cyclobutenylidene Complexes and Cyclobutenones from Vinylidene Complexes and Electron-Rich AlkynesPentacarbonyl(vinylidene) complexes of chromium and tungsten, (CO)5M=C=C(R1)R2 (1) [M=W: R1=R2=Ph (a), R1 = tBu, R2=Et (b), Me (c); M=Cr: R1=tBu, R2=Me (d)] react with 1-(diethylamino)-1-propyne by regiospecific addition of the C≡C bond of the alkyne to the Cα=Cβ bond of the vinylidene ligand to form the cyclobutenylidene complexes 2a-d. Oxidative cleavage of the cyclobutenylidene ligand from 2a-d gives the corresponding cyclobutenones. The reactions of 1b with bis(diethylamino)acetylene and of 1a with 1-ethoxy-1-propyne afford the cyclobutenylidene complexes 3b and 4a, respectively. In contrast, 1a reacts with diorganylcyanamides, N≡CNR2 (R=Me, Et, iPr), by ligand displacement and formation of tetraphenylbutatriene and diorganyl-cyanamide complexes. The structures of 2c and 4a were established by X-ray analyses.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921251208
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  • 3
    Electronic Resource
    Electronic Resource
    Ring Expansion of Spirocyclic Cyclobutenylidene Ligands in Pentacarbonylchromium Complexes to Tetrahydroindene Derivatives (1996)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996), S. 615-622 
    Details
    ISSN: 0009-2940
    Keywords: Vinylidene complexes ; Cyclobutenylidene complexes ; Tetrahydroindenes ; Thioether complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Pentacarbonyl(pentamethylenevinylidene)chromium, [(CO)5Cr=C=C(CH2)5] (1), reacts with 1-methylthio-1-propyne (2a) and N-(1-propynyl)phenothiazine (2b) by regio-specific addition of the C=C bond of the alkyne to the C=C bond of the vinylidene ligand of 1. Initially, complexes with a spirocyclic cyclobutenylidene ligand are formed, [(CO)5Cr=(CH2)5] (3) and [(CO)5-Cr=(CH2)5] (10). Subsequent thermally initiated ring expansion affords the 2-methyl-4,5,6,7-tetrahydroindenyl(methyl)thioether complex [(CO)5-Cr-S(Me)(Me-C9H10)] (4) and the N-(2-methyl-4,5,6,7-tetrahydroindenyl)phenothiazine complex [(CO)5Cr-S(C6H4)2-N-(Me-C9H10)] (11), respectively. In both complexes, 4 and 11 the ligand is coordinated to the metal via the sulfur atom. The constitutions were established by (H,H)-, (H,C)- and NOE-correlated NMR spectroscopy. In the reaction of 1 with 2a, in addition to 3 and 4, the methyl(propynyl)thioether complex [(CO)5Cr-S(Me)C≡CMe] (5) was formed. An isolable 3-methylthio-substituted cyclobutenylidene complex, [(CO)5Cr=Ph2] (9) was obtained from [(CO)5Cr=C=CPh2] (8) and 2a. The 4,5,6,7-tetrahydroindenylthioether ligand of 11 was cleaved from the metal by exposure of 11 adsorbed on silica gel to air or by treatment of 11 with [NEt4]Br in dichloromethane.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19961290605
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  • 4
    Electronic Resource
    Electronic Resource
    Di-, Tri-, and Tetranuclear Cyclobutenylidene Complexes (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 1225-1234 
    Details
    ISSN: 1434-1948
    Keywords: Vinylidene complexes ; Cyclobutenylidene complexes ; Bridging ligands ; Cycloadditions ; Cross-coupling ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Pentacarbonyl(dimethylvinylidene)chromium, [(CO)5Cr=C=CMe2] (1), reacts with the butadiynyl complexes [Cp(CO)2FeC≡CC≡CR] [2; R = SiMe3 (a), nBu (b), Ph (c)] and [Cp(CO)(PPh3)FeC≡CC≡CSiMe3] (3a) by regiospecific cycloaddition of the Cα≡Cβ bond of the butadiynyl complexes to the C=C bond of 1 to form the 1,3-heterobinuclear cyclobutenylidene complexes 4a-c and 5a with an alkynyl substituent at C-2 of the bridging ring. Desilylation of the 2-C≡CSiMe3 substituent in 4a and 5a with tetrabutylammonium fluoride affords the 2-C≡CH-substituted complexes 6 and 7. Complex 4a reacts with HNMe2 and HN(CH2)5 by substitution of NR2 for the 3-Fe(CO)2Cp fragment to form the corresponding 3-aminocyclobutenylidene complexes 10 and 11. Sequential reactions of 4a with [nBu4N]F and nBu3SnNEt2 give the trinuclear 2-C≡CSnnBu3-substituted complex 12. Coupling of 12 with C6H4I2-p yields the 2-C≡CC6H4I-p-substituted complex 13. Coupling of 7 with C6H4I2-p yields a mixture of the mono-coupling product 14 and the tetranuclear C≡C-C6H4-C≡C-bridged bis(cyclobutenylidene) complex 15. Coupling of 7 with trans-[(Et3P)2MCl2] in the presence of CuI/[Pd(PPh3)4] gives the trinuclear 2-C≡C-M(PEt3)2X-substituted complexes 16 (M = Pd, × = I) and 17 (M = Pt, × = Cl). The spectroscopic data as well as the results of the X-ray-structural analysis of 5a indicate strong electronic communication between the metal centers. In the solid state, 5a exhibits a “butterfly” conformation.
    Type of Medium: Electronic Resource
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