Synthesis and reactivity of metal carbene complexes with heterobiaryl spacer substituents

Lotz, Simon; Crause, Chantelle; Olivier, A.; Liles, David C.; Görls, Helmar; Landman, Marilé; Bezuidenhout, Daniela Ina

doi:10.1039/b811762d

Cited by 27 publications

(37 citation statements)

References 56 publications

(73 reference statements)

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“…[Cr(CO) 5 C(OEt)(2-(N-methylpyrrolyl))] (3) [16] and [Cr(CO) 5 C(OEt)(N-methyl-2-(2'-thienyl)pyrrole)] (4) [38]. Characterization data of 1-4 were in agreement with these literature reports.…”

supporting

confidence: 85%

“…[Cr(CO) 5 C(OEt)2,2'-thienylfuran] (5) [38] 2,2′-Thienylfuran (0.38 g, 2.5 mmol) was dissolved in tetrahydrofuran (THF) (30 ml) and the solution cooled to -20 °C. 1.7 ml (2.8 mmol) of a 1.6 M solution of n-BuLi in hexane was added and the reaction mixture stirred for 30 minutes.…”

Section: Synthesismentioning

confidence: 99%

“…Triethyloxonium tetrafluoroborate was prepared according to a literature procedure [15]. The following dimeric heteroarene precursors and carbene complexes were synthesized according to known literature methods: 2,2'-Thienylfuran (A) [38] and N-methyl-2-(2'-thienyl)pyrrole (B) [38],…”

mentioning

confidence: 99%

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Electrochemistry of Fischer alkoxycarbene complexes of chromium: The use of density functional theory to predict and understand oxidation and reduction potentials

Landman

Liu

Rooyen

et al. 2013

Electrochimica Acta

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The electrochemical behaviour of a series of Fischer ethoxycarbene complexes of the type [(CO) 5 Cr=C(OEt)R] with R = 2-thienyl (1), 2-furyl (2), 2-(N-methylpyrrolyl) (3), N-methyl-2-(2'-thienyl)pyrrole) (4) and 2,2'-thienylfuran (5), is investigated by means of cyclic voltammetry. Results show that the first one electron reduction process is sensitive to the energy, shape and distribution of the LUMO orbital, leading to a linear relationship between the formal reduction potential and the LUMO energy: E 0' (C carbene ) = -0.70 E LUMO -3.44 (R 2 = 1.00) which is valid over a large potential 2 range. The dimeric heteroarene substituents of 4 and 5 lead to enhanced stabilization of the reduced complexes 4 and 5, making another one electron reduction possible.The formal reduction potential, E 0' (Cr) of the first oxidation process of 1-5 lays within a narrow potential range of 0.43 to 0.50 V vs. Fc/Fc + , is Cr-based and is mainly sensitive to the electrophilic character of the heteroarene ring directly attached to the carbene carbon.

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confidence: 85%

Section: Synthesismentioning

confidence: 99%

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Electrochemistry of Fischer alkoxycarbene complexes of chromium: The use of density functional theory to predict and understand oxidation and reduction potentials

Landman

Liu

Rooyen

et al. 2013

Electrochimica Acta

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“…Thiophene was purified as described in literature, prior to use [11]. The following dimeric heteroarene precursors were synthesized according to known literature methods: 2,2'-Thienylfuran (A) [13] and 4 N-methyl-2-(2'-thienyl)pyrrole (B) [13]. For the carbene complexes, well-known Fischer synthetic methodology was used [1] [20].…”

Section: Generalmentioning

confidence: 99%

“…The detailed synthesis and characterization of most of the complexes of this study have been reported previously [13][14][15][16][17][18][19][20]. Complex (5) was synthesized according to the analogous methoxy complex reported in literature [13] and characterization data are similar.…”

Section: Synthesis Characterisation and X-ray Crystallographymentioning

confidence: 99%

Fischer mono- and biscarbene complexes of tungsten with mono- and dimeric heteroaromatic substituents

Landman

Buitendach

Conradie

et al. 2015

Journal of Electroanalytical Chemistry

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An electrochemical study of a series of mono and biscarbene complexes of tungsten pentacarbonyl with mono-and dimeric heteroarene substituents are reported and compared in CH 3 CN and DCM.Results revealed that the order of oxidation (reduction) depends largely on the aryl substituent attached to the carbene carbon (2-thienyl, 2-furyl or 2-(N-methylpyrrolyl)). The order of oxidation (reduction) for monocarbene complexes containing a monomeric heteroarene substituent ((1) -(3)), a dimeric heteroarene substituent ((4) -(6)) or biscarbene complexes connected with a heteroarene substituent ( (7) - (9)) is the same, namely 2-thienyl > 2-furyl > 2-(N-methylpyrrolyl). Carbene complexes containing a larger conjugated heteroarene substituent attached to the carbene carbon reduce more easily than the monomeric analogues. Tungsten biscarbene complexes exhibit two separate oxidation potentials for the two metal centres or one large oxidation peak, consistent with the simultaneous oxidation of the two W metal centres.

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Redox Behaviour of Cymantrene Fischer Carbene Complexes in Designing Organometallic Multi‐tags

Bezuidenhout

Westhuizen

Swarts

et al. 2014

Chemistry A European J

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All complexes showed that the redox potentials of carbene double bond reduction and Mn(I) oxidation were dependent on the type of Ar group, but only 3b showed resolved oxidations for the two Mn(I) centres. Surprisingly, Mn(I) oxidation occurs at lower potentials than ferrocenyl oxidation. Density functional theory (DFT) calculations were carried out to delineate the nature of the species involved in the oxidation and reduction processes and clearly confirm that oxidation of Mn(I) is favoured over that of ferrocene.

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Synthesis and reactivity of metal carbene complexes with heterobiaryl spacer substituents

Abstract: 4 ] to afforded the carbene-carbene coupled olefinic products and small amounts of the corresponding 2-ethyl(biheteroaryl)acetate. By contrast, the biscarbene complex of thienylfuran (15), afforded only the 2,9-diester of thienylfuran.

Cited by 27 publications

References 56 publications

Electrochemistry of Fischer alkoxycarbene complexes of chromium: The use of density functional theory to predict and understand oxidation and reduction potentials

Electrochemistry of Fischer alkoxycarbene complexes of chromium: The use of density functional theory to predict and understand oxidation and reduction potentials

Fischer mono- and biscarbene complexes of tungsten with mono- and dimeric heteroaromatic substituents

Redox Behaviour of Cymantrene Fischer Carbene Complexes in Designing Organometallic Multi‐tags

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