Electrochemical behaviour and structure of novel phosphine- and phosphite-substituted tungsten(0) Fischer carbene complexes

Landman, Marilé; Pretorius, René; Fraser, Roan; Buitendach, Blenerhassit E.; Conradie, Marrigje M.; Rooyen, Petrus H. van; Conradie, Jeanet

doi:10.1016/j.electacta.2014.02.127

Cited by 31 publications

(48 citation statements)

References 59 publications

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“…The cis isomers are generally more stable, although it was possible to isolate the trans isomer for related phosphine-substituted Fischer ethoxy carbene tungsten (0) complexes [6,11].…”

Section: Electrochemical Studymentioning

confidence: 99%

“…The reduction process is ascribed to the one electron reduction of the carbene carbon, as described in the DFT section above, as well as for related carbene complexes of tungsten [6,7,28]. The reduction process of 1-2 is enhanced at higher scan rates, with a peak current separation, ΔE, of 0.070-0.075 V. This implies that the radical anion that forms upon reduction is stabilized long enough on the timescale of the CV to be oxidized back to the neutral complex.…”

Section: Electrochemical Studymentioning

confidence: 99%

“…In a recent study by our group [6], it was shown that the phosphinesubstituted Fischer ethoxy carbene complexes of tungsten(0) are more electrochemically active than the non-substituted pentacarbonyl tungsten(0) Fischer ethoxycarbene complexes [(CO) 5 WC(OEt)(Ar)] complexes for Ar = 2-thienyl and 2-furyl [7]. Altering the R-groups of the phosphine ligand (PR 3 ) from Ph to OPh, showed to have a negligible effect on the electrochemical behaviour, while substitution of the ethoxy-group on the carbene carbon with various amine substituents [6] showed a marked effect on both the metal oxidation potential (0.08 -0.19 V) as well as the carbene ligand reduction potential (0.30 -0.52 V). It was also found that the order of oxidation (and reduction) for monocarbene complexes containing a monomeric heteroarene substituent, a dimeric heteroarene substituent or biscarbene complexes connected with a heteroarene spacer substituent is the same, namely 2-thienyl > 2-furyl > 2-(Nmethylpyrrolyl) [8].…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…Electrochemical analyses of group 6 Fischer carbene complexes reported includes Fischer carbene complexes of the metals chromium(0) [1][2][3] molybdenum(0) [4,5] and tungsten(0) [6,7]. In a recent study by our group [6], it was shown that the phosphinesubstituted Fischer ethoxy carbene complexes of tungsten(0) are more electrochemically active than the non-substituted pentacarbonyl tungsten(0) Fischer ethoxycarbene complexes [(CO) 5 WC(OEt)(Ar)] complexes for Ar = 2-thienyl and 2-furyl [7]. Altering the R-groups of the phosphine ligand (PR 3 ) from Ph to OPh, showed to have a negligible effect on the electrochemical behaviour, while substitution of the ethoxy-group on the carbene carbon with various amine substituents [6] showed a marked effect on both the metal oxidation potential (0.08 -0.19 V) as well as the carbene ligand reduction potential (0.30 -0.52 V).…”

Section: Introductionmentioning

confidence: 99%

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Electrochemistry of Triphenylarsine-substituted Tungsten(0) Fischer carbene complexes

Rensburg

Landman

Westhuizen

et al. 2015

Electrochimica Acta

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“…The cis isomers are generally more stable, although it was possible to isolate the trans isomer for related phosphine-substituted Fischer ethoxy carbene tungsten (0) complexes [6,11].…”

Section: Electrochemical Studymentioning

confidence: 99%

Section: Electrochemical Studymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Electrochemistry of Triphenylarsine-substituted Tungsten(0) Fischer carbene complexes

Rensburg

Landman

Westhuizen

et al. 2015

Electrochimica Acta

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Photochemical Unmasking of 1,3‐Dithiol‐2‐ones: An Alternative Route to Heteroleptic Dithiolene Complexes from Low‐Valent Molybdenum and Tungsten Precursors

2019

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Mono-dithiolene complexes [Mo(CO) 2 (dt)(dppe)] and [W(CO) 2 (dt)(dppe)] {dt = cyclohex-1-ene-1,2-dithiol; 5,6-dihydro-2H-pyran-3,4-dithiol and dppe= 1,2-bis(diphenylphosphino)ethane} were synthesized by a photochemical procedure. The typical basic de-protection of the dithiolene ligand precursor was replaced by a light-induced opening of the 1,2-dithiole-2-one moiety. Advantages of this targeted approach comprise higher yields, cleaner transformations, and the possibility to continuously and precisely monitor the reaction progress. The [a] Scheme 1. Literature known pathways towards 1,2-dithiones and their tautomers: i. Nickel transfer metalation [7] ii. Chelotropic reaction of 1,3-dithiol-2ones initiated by UV-light [8] or heat [9] iii. Sulfuration of acetylenic compounds [10] iv. Sulfuration of dioxamides [11] v. Synthesis from thiirenes-1-oxides and Lawesson's Reagent. [12] tainly feasible approach towards metal-dithiolene complexes would be the direct use of 1,2-dithiones or their valence tautomers, [15] the 1,2-dithietes. This strategy was applied successfully to Pd, Ni, Co, Ru and Fe carbonyl precursors yielding bis-and trisdithiolene complexes. [15,16] With respect to the metals of our interest (Mo, W), in one case the reaction between the easily accessible bis(trifluoromethyl)-dithiete with hexacarbonyl molybdenum was described to yield 55 % of [Mo(S 2 C 4 F 6 ) 3 ]. [17] 1,2-Dithietes are commonly prepared by the reaction of elemental sulfur with the appropriate alkyne (Scheme 1; iii.) while not any alkyne leads to a wanted dithiete or dithione, though. [10,16b,18] The equilibrium between both tautomers is highly dependent on the backbone. Thus, electron-donating substituents usually stabilize dithiones [S 2 C 2 R 2 ; R = (p-dimethylamino)phenyl, 1-adamantyl] [8,19] while electron-withdrawing substituents favor dithietes which was established for the cases S 2 C 2 (CF 3 ) 2 , S 2 C 2 (CO 2 Me) 2 , and S 2 C 2 (CN) 2 . [9,20] Both, dithiones and dithietes are, however, undoubtedly unstable unless stabilized either electronically or sterically as they constitute reactive transient intermediates. [12] Comparably stable 1,2-dithiones are available from dioxamides upon thionation with Lawesson's Reagent (Scheme 1; iv.). [11] These specific species were first tested for the oxidative addition to molybdenum by Dieck and Form followed by only two related reports more than two decades later. [21] Electron donating dithiolenes which are not sterically hindered as for instance cyclic ones [e.g. cylohex-1-ene-1,2-dithiol (cydt) [22] or 5,6-dihydro-2H-pyran-3,4-dithiol (pydt) [23] ] or the well known S 2 C 2 Me 2 (mdt) [13] are neither isolable as dithiones/ dithietes nor as their unprotected alkali salts. Instead, precursors for this type of dithiolene ligand are commonly prepared in their 1,3-dithiol-2-one form. In order to coordinate such dithiolenes to metal carbonyl precursors their corresponding dithiones can be prepared in situ via a photochemically driven chelotropic decarbonylation (Scheme 1; ii.). ...

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The Effect of Remote Donor Substituents on the Properties of Alkoxy and Amino Fischer Carbene Complexes of Tungsten

Weststrate

Hassenrück

Linseis

et al. 2021

Zeitschrift anorg allge chemie

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Dedicated to Prof. Wolfgang Kaim on the Occasion of his 70th BirthdayTungsten Fischer ethoxy-and dimethylaminocarbene complexes [W{C(X)(C 6 H 4 -4-R}(CO) 5 ] (X = OEt: series a; or X = NMe 2 : series b) are synthesized from phenyl substrates containing remote tertiary amino substituents R' 2 N with R' = Me (2), Ph (3) or C 6 H 4 Br-4 (4). The π-delocalization and carbene-stabilizing effects of the distant tertiary amine donor substituent are investigated by NMR and IR spectroscopy, electrochemistry and quantum chemical calculations. A significant transfer of electron density from the remote 4-R' 2 N substituent to the carbene C atom in the ethoxycarbene complexes is supported by NMR data and the solid-state structure of 2 a. This is strongly attenuated in the amino-substituted carbene complex 2 c and irrelevant in the dimethylaminocarbene complexes of series b, where the electron demand of the electrophilic carbene center is satisfied by the directly attached dimethylamino substituent. Quantum chemical calculations and IR spectroelectrochemistry on complexes 1 a--4 a verify carbene-centered reductions and a ligand based oxidation of complex 2 b.

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Electrochemical behaviour and structure of novel phosphine- and phosphite-substituted tungsten(0) Fischer carbene complexes

Cited by 31 publications

References 59 publications

Electrochemistry of Triphenylarsine-substituted Tungsten(0) Fischer carbene complexes

Electrochemistry of Triphenylarsine-substituted Tungsten(0) Fischer carbene complexes

Photochemical Unmasking of 1,3‐Dithiol‐2‐ones: An Alternative Route to Heteroleptic Dithiolene Complexes from Low‐Valent Molybdenum and Tungsten Precursors

The Effect of Remote Donor Substituents on the Properties of Alkoxy and Amino Fischer Carbene Complexes of Tungsten

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