<sup>13</sup>C-NMR-Spektren p-substituierter Phenylcyclobutadien-eisentricarbonyle / <sup>13</sup>C-MRR-Spectra of p-Substituted Cyclobutadiene-irontricarbonyls

Brune, Hans Albert; Horlbeck, Gernot

doi:10.1515/znb-1973-9-1019

Cited by 6 publications

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“…In previous work (Brune & Horlbeck, 1973) the influence of substituents on the phenyl rings on the bonding properties and structures of tricarbonyl-(1,2-diphenylcyclobutadiene)iron(III) complexes were studied with NMR. The observation and interpretation 0108-2701/87/020221-04501.50 of different nuclear spin-spin coupling constants lead to the conclusion that significant modifications of the molecular geometry of the four-membered ring and its bonding to the central atom with change of electronic character of the substituents occur.…”

mentioning

confidence: 99%

(η5-Cyclopentadienyl){η4-[1,3-bis(4-methoxyphenyl)-2,4-bis(trimethylsilyl)]cyclobutadiene}cobalt(I) (1) and (η5-cyclopentadienyl){η4-[1,3-bis(trifluoromethylphenyl)-2,4-bis(trimethylsilyl)]cyclobutadiene}cobalt(I) (2)

Debaerdemaeker¹,

Grafl²,

Brune³

1987

Acta Crystallogr C

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(1) and (2), no significant influence on the molecular structure within the coordination sphere is detected. In both compounds, the Co atom is half-way between the planes of the four-and five-membered coordinated rings. The cyclobutadiene ring is slightly contracted along the diagonal between the phenylsubstituted C atoms.lntroduetlon. In previous work (Brune & Horlbeck, 1973) the influence of substituents on the phenyl rings on the bonding properties and structures of tricarbonyl-(1,2-diphenylcyclobutadiene)iron(III) complexes were studied with NMR. The observation and interpretation 0108-2701/87/020221-04501.50 of different nuclear spin-spin coupling constants lead to the conclusion that significant modifications of the molecular geometry of the four-membered ring and its bonding to the central atom with change of electronic character of the substituents occur. To observe these changes directly, the crystal structure analysis was undertaken of both title compounds whose phenyl rings are substituted with a methoxy group in (1) as a strong ~r-donating substituent and the trifluoromethyl group in (2) as an efficient inductive a-attracting one.Experimental. Crystals of both title compounds are red-brown; (1) crystallizes in the form of elongated parallelepipeds, (2) in the form of octahedra, both with well developed faces. (1) Crystal 0.2 x 0.2 x 0.4mm; (2) crystal 0.2 x 0.1 x 0.3mm. 4914 (1) and 5643 (2) independent unique reflections; Philips PW 1100 four-circle diffractometer; Mo Ka radiation, graphite monochromator; 0-20 scan, 3188 observed reflections for (1) [F > 1.5a(F), -26 < h < 25, 0 < k < 10, 0 < l < 16, 0mi n = 2, /~max = 25°] and 3955 observed reflections for (2) [F > 1.5e(F), -21 < h < 21, 0 < k < 16, 0 < l < 15, 0m~, = 2, Omax = 25°]" The intensity of three standards did not vary during the period of measurement. The cell parameters were

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mentioning

confidence: 99%

(η5-Cyclopentadienyl){η4-[1,3-bis(4-methoxyphenyl)-2,4-bis(trimethylsilyl)]cyclobutadiene}cobalt(I) (1) and (η5-cyclopentadienyl){η4-[1,3-bis(trifluoromethylphenyl)-2,4-bis(trimethylsilyl)]cyclobutadiene}cobalt(I) (2)

Debaerdemaeker¹,

Grafl²,

Brune³

1987

Acta Crystallogr C

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“…Für das -durch koordinative Bindung an Über-gangsmetalle stabilisierte -Cyclobutadien darf für die Gasphase [1][2][3][4], für die in indifferenten Lösungs-mitteln gelöste Form [5][6][7][8][9] und für die kristalline Phase [10][11][12][13][14][15] die quadratisch-ebene Struktur des Vierrings im Rahmen der Meßgenauigkeit der angewendeten Methoden als gesichert gelten. Angesichts der in den letzten Jahren erfolgten Ausarbeitung verfeinerter experimenteller Techniken in der Röntgenstruktur-Analyse hatten wir begonnen, unser Augenmerk auf den Einfluß der übrigen in Cyclobutadien-Metall-Komplexen an das Zentralmetall gebundenen Liganden auf die BindungsVerhältnisse innerhalb des Vierrings und auf die Bindungs-Beziehungen zwischen Cyclobutadien und Zentralmetall zu richten.…”

unclassified

Kristall-und Molekülstruktur des (Tetramethylcyclobutadien)cis-1.2-dicyano-ethen-1.2-dithiolato-nickel(II) /Crystal and Molecular Structure of (Tetramethylcyclobutadiene)cis-1,2-dicyano-ethene-1,2-dithiolato-nickel(II)

Hemmer

Brune

Thewalt

1981

Zeitschrift Für Naturforschung B

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AbstractSingle crystals of the title compound, A, have been prepared and studied structurally by X-ray analysis. A crystallizes in the space group P21/n with Z = 4 and lattice parameters a = 11.174(3), b= 15.627(5), c= 8.148(3) Å and β = 92.82(3)°. Within the limits of error the π-bonded cyclobutadiene ring is a square with an average C-C-bond distance of 1.465 Å ; the methyl groups are displaced away from the nickel atom, the average distance between the ring plane and the methyl C-atoms being 0.15 Å. The sulfur containing five membered ring has a cyclic delocalized electron distribution.

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Cycloheptatriene and fulvene Cr(CO)₃ complexes

1978

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1,6-Methano[lO]annulene-Cr(CO), and several related complexes adopt an anomalous orientation of the Cr(CO), unit with respect to the polyene, compared to all other hexatriene-Cr(CO), complexes. A theoretical analysis of this problem shows that these conformational preferences are closely related to the cycloheptatriene-norcaradiene valence tautomerism. Several strategies for influencing the barrier to internal rotation in these complexes are presented. An analysis of the conformational preference, rotational barrier, and bending of the exocyclic methylene group in fulvene-Cr(CO), is also discussed. This is extended to the analogous benzyl-Cr(CO), and cyclobutadiene-carbinyl-Fe(CO), cations. Finally, the orientations of these complexes are contrasted to those containing two more electrons. Cycloheptatrien-nnd Fulven-Cr(CO),-KomplexeIm Tricarbonylchrom(0)-Komplex von 1,6-Methano[ 10]annulen und in einigen verwandten Komplexen nimmt die Cr(CO),-Einheit verglichen mit allen anderen Hexatrien-Cr(CO),-Systemen eine anomale Orientierung relativ zum Polyen ein. Eine theoretische Analyse dieses Problems zeigt, daD diese Vorzugskonformation eng mit der Cycloheptatrien-Norcaradien-Valenztautomerie zusammenhangt. Mogliche Wege, die Rotationsbarriere in derartigen Komplexen zu beeinflussen, werden aufgezeigt. Vorzugskonformation, Rotationsbarriere und Abknicken der exocyclischen Methylengruppe in Tricarbonyl(q6-fulven)chrom(0) werden diskutiert und die Analyse wird auf die analogen Benzyl-Cr(CO),-und Cyclobutadiencarbinyl-Fe(CO),-Kationen ausgedehnt. Die Konformation dieser Komplexe wird solchen gegenubergestellt, die zwei Elektronen mehr enthalten.In the vast majority of hexatriene-ML, complexes a single conformation 1 is chosen 'I. The unique carbonyl or other substituent of the ML3 fragment is positioned over the "open" side of the polyene ribbon. There is a substantial barrier, 2 11 -12 kcal/mole*), la) P. E . Baikie and 0. S. Mills, J. Chem. SOC. A 1968, 2704.l h ) M .

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¹³C-NMR-Spektren p-substituierter Phenylcyclobutadien-eisentricarbonyle / ¹³C-MRR-Spectra of p-Substituted Cyclobutadiene-irontricarbonyls

Abstract: The electronic interaction between complex bonded cyclobutadiene and the phenyl ring is analyzed by 13C- and 1H-NMR-spectra. The cyclobutadiene-irontricarbonyl acts electron donating via the π-system and electron accepting via the σ-core.

Cited by 6 publications

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(η5-Cyclopentadienyl){η4-[1,3-bis(4-methoxyphenyl)-2,4-bis(trimethylsilyl)]cyclobutadiene}cobalt(I) (1) and (η5-cyclopentadienyl){η4-[1,3-bis(trifluoromethylphenyl)-2,4-bis(trimethylsilyl)]cyclobutadiene}cobalt(I) (2)

(η5-Cyclopentadienyl){η4-[1,3-bis(4-methoxyphenyl)-2,4-bis(trimethylsilyl)]cyclobutadiene}cobalt(I) (1) and (η5-cyclopentadienyl){η4-[1,3-bis(trifluoromethylphenyl)-2,4-bis(trimethylsilyl)]cyclobutadiene}cobalt(I) (2)

Kristall-und Molekülstruktur des (Tetramethylcyclobutadien)cis-1.2-dicyano-ethen-1.2-dithiolato-nickel(II) /Crystal and Molecular Structure of (Tetramethylcyclobutadiene)cis-1,2-dicyano-ethene-1,2-dithiolato-nickel(II)

Cycloheptatriene and fulvene Cr(CO)₃ complexes

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13C-NMR-Spektren p-substituierter Phenylcyclobutadien-eisentricarbonyle / 13C-MRR-Spectra of p-Substituted Cyclobutadiene-irontricarbonyls

Abstract: The electronic interaction between complex bonded cyclobutadiene and the phenyl ring is analyzed by 13C- and 1H-NMR-spectra. The cyclobutadiene-irontricarbonyl acts electron donating via the π-system and electron accepting via the σ-core.

Cited by 6 publications

References 0 publications

(η5-Cyclopentadienyl){η4-[1,3-bis(4-methoxyphenyl)-2,4-bis(trimethylsilyl)]cyclobutadiene}cobalt(I) (1) and (η5-cyclopentadienyl){η4-[1,3-bis(trifluoromethylphenyl)-2,4-bis(trimethylsilyl)]cyclobutadiene}cobalt(I) (2)

(η5-Cyclopentadienyl){η4-[1,3-bis(4-methoxyphenyl)-2,4-bis(trimethylsilyl)]cyclobutadiene}cobalt(I) (1) and (η5-cyclopentadienyl){η4-[1,3-bis(trifluoromethylphenyl)-2,4-bis(trimethylsilyl)]cyclobutadiene}cobalt(I) (2)

Kristall-und Molekülstruktur des (Tetramethylcyclobutadien)cis-1.2-dicyano-ethen-1.2-dithiolato-nickel(II) /Crystal and Molecular Structure of (Tetramethylcyclobutadiene)cis-1,2-dicyano-ethene-1,2-dithiolato-nickel(II)

Cycloheptatriene and fulvene Cr(CO)3 complexes

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¹³C-NMR-Spektren p-substituierter Phenylcyclobutadien-eisentricarbonyle / ¹³C-MRR-Spectra of p-Substituted Cyclobutadiene-irontricarbonyls

Cycloheptatriene and fulvene Cr(CO)₃ complexes