Anomalous ligand field effects in complexes of quadridentate ligands containing group V donors

Higginson, Brian R.; McAuliffe, Charles A.; Venanzi, L. M.

doi:10.1016/s0020-1693(00)95876-6

Cited by 33 publications

(14 citation statements)

References 12 publications

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“…These considerations led us to focus on the triphosphanylstibine ligand [(o-(Ph 2 P)C 6 H 4 ) 3 Sb] (referred to as L) [10] which was allowed to react with [AuCl(tht)] in CH 2 Cl 2 /acetone to produce 1-Cl as a pale yellow precipitate (Scheme 1). At À55 8C in CDCl 3 , the 31 P{ 1 H} NMR spectrum of 1-Cl displays two signals at d = + 39.5 and À7.4 ppm in a 2:1 intensity ratio thus suggesting that only two of the three phosphine arms of the ligand are coordinated to the gold atom.…”

mentioning

confidence: 99%

“…With the discovery of main-group-based, two-electron redox platforms in mind, we have now decided to study the synthesis and oxidation of complexes of type B. Herein, we report the first incarnation of this idea in the case of a gold-antimony compound.To prevent dissociation of the gold-antimony bimetallic core upon oxidation, we chose to work with a stibine ligand whose interaction with the gold center would be supported by pendant donor ligands. These considerations led us to focus on the triphosphanylstibine ligand [(o-(Ph 2 P)C 6 H 4 ) 3 Sb] (referred to as L) [10] which was allowed to react with [AuCl(tht)] in CH 2 Cl 2 /acetone to produce 1-Cl as a pale yellow precipitate (Scheme 1). At À55 8C in CDCl 3 , the 31 P{ 1 H} NMR spectrum of 1-Cl displays two signals at d = + 39.5 and À7.4 ppm in a 2:1 intensity ratio thus suggesting that only two of the three phosphine arms of the ligand are coordinated to the gold atom.…”

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confidence: 99%

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Two‐Electron Redox Chemistry and Reversible Umpolung of a Gold–Antimony Bond

Wade

Gabbaı̈

2011

Angew Chem Int Ed

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Two-electron redox processes occurring at the core of dinuclear metal complexes are important because of their implication in a number of chemical transformations ranging from the photocatalytic production of dihydrogen [1] to the oxidative functionalization of CÀH bonds.[2] Two-electron redox processes are also well documented for binuclear gold complexes [3] as well as for gold/rhodium, [4] gold/iridium [5] and gold/platinum [6] heterobimetallic complexes. One of the common features displayed by all of these complexes relates to their ability to sustain two-electron redox chemistry without decomposition of the bimetallic core. As part of our interest in fundamental aspects of main-group chemistry, we have recently questioned whether similar processes could also be observed at the bimetallic core of main-group/transitionmetal complexes.Triarylstibines are soft s-donor ligands which have been incorporated in a variety of late transition-metal complexes. [7] They are also well known to undergo facile two-electron oxidation when exposed to oxidizing agents such as halogens.[8] While there is precedent for dialkylstibido transitionmetal compounds (type A) to undergo oxidative addition at the antimony center, [9] no analogous reactivity has been reported for stibine metal complexes of type B. With the discovery of main-group-based, two-electron redox platforms in mind, we have now decided to study the synthesis and oxidation of complexes of type B. Herein, we report the first incarnation of this idea in the case of a gold-antimony compound.To prevent dissociation of the gold-antimony bimetallic core upon oxidation, we chose to work with a stibine ligand whose interaction with the gold center would be supported by pendant donor ligands. These considerations led us to focus on the triphosphanylstibine ligand [(o-(Ph 2 P)C 6 H 4 ) 3 Sb] (referred to as L) [10] which was allowed to react with [AuCl(tht)] in CH 2 Cl 2 /acetone to produce 1-Cl as a pale yellow precipitate (Scheme 1). At À55 8C in CDCl 3 , the 31 P{ 1 H} NMR spectrum of 1-Cl displays two signals at d = + 39.5 and À7.4 ppm in a 2:1 intensity ratio thus suggesting that only two of the three phosphine arms of the ligand are coordinated to the gold atom. Upon elevation of the temperature, these two peaks coalesce into one signal at d = + 24.4 ppm indicating the onset of a rapid exchange. Line shape analysis of the 31 P{ 1 H} NMR spectra of 1-Cl over the À55 8C-+ 22 8C temperature range followed by an Eyring analysis afforded DH°= + 16.7 (AE 0.9) kcal mol À1 and DS°= + 16.6(AE3.8) cal mol À11 K À11 , suggesting a dissociative exchange of the phosphine arms. The ESI mass spectrum of this complex shows a peak at m/z 1101.1180 amu corresponding to the [LAu] + ion. A final clarification of the structure of this compound was derived from a single-crystal diffraction study which confirmed the coordination of two of the phosphorus atoms to the gold chloride fragment (Figure 1).[11] Inspection of the P-Au-P and P-Au-Cl angles (AE = 359.468) shows that these prim...

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confidence: 99%

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confidence: 99%

Two‐Electron Redox Chemistry and Reversible Umpolung of a Gold–Antimony Bond

Wade

Gabbaı̈

2011

Angew Chem Int Ed

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“…SbCl 3 was purchased from Alfa Aesar, NaI was purchased from Aldrich, and both were used as received. The ligand [(o-(Ph 2 P)C 6 H 4 ) 3 Sb], [10] PhICl 2 , [19] and [(tht)AuCl] [20] (tht = tetrahydrothiophene) were prepared according to the reported procedures. All air and moisture sensitive manipulations were carried out under an atmosphere of dry N 2 employing either a glove box or standard Schlenk techniques.…”

Section: Methodsmentioning

confidence: 99%

Two‐Electron Redox Chemistry and Reversible Umpolung of a Gold–Antimony Bond

Wade¹,

Gabbaı̈²

2011

Angewandte Chemie

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Two-electron redox processes occurring at the core of dinuclear metal complexes are important because of their implication in a number of chemical transformations ranging from the photocatalytic production of dihydrogen [1] to the oxidative functionalization of CÀH bonds. [2] Two-electron redox processes are also well documented for binuclear gold complexes [3] as well as for gold/rhodium, [4] gold/iridium [5] and gold/platinum [6] heterobimetallic complexes. One of the common features displayed by all of these complexes relates to their ability to sustain two-electron redox chemistry without decomposition of the bimetallic core. As part of our interest in fundamental aspects of main-group chemistry, we have recently questioned whether similar processes could also be observed at the bimetallic core of main-group/transitionmetal complexes.Triarylstibines are soft s-donor ligands which have been incorporated in a variety of late transition-metal complexes. [7] They are also well known to undergo facile two-electron oxidation when exposed to oxidizing agents such as halogens. [8] While there is precedent for dialkylstibido transitionmetal compounds (type A) to undergo oxidative addition at the antimony center, [9] no analogous reactivity has been reported for stibine metal complexes of type B. With the discovery of main-group-based, two-electron redox platforms in mind, we have now decided to study the synthesis and oxidation of complexes of type B. Herein, we report the first incarnation of this idea in the case of a gold-antimony compound.To prevent dissociation of the gold-antimony bimetallic core upon oxidation, we chose to work with a stibine ligand whose interaction with the gold center would be supported by pendant donor ligands. These considerations led us to focus on the triphosphanylstibine ligand [(o-(Ph 2 P)C 6 H 4 ) 3 Sb] (referred to as L) [10] which was allowed to react with [AuCl(tht)] in CH 2 Cl 2 /acetone to produce 1-Cl as a pale yellow precipitate (Scheme 1). At À55 8C in CDCl 3 , the 31 P{ 1 H} NMR spectrum of 1-Cl displays two signals at d = + 39.5 and À7.4 ppm in a 2:1 intensity ratio thus suggesting that only two of the three phosphine arms of the ligand are coordinated to the gold atom. Upon elevation of the temperature, these two peaks coalesce into one signal at d = + 24.4 ppm indicating the onset of a rapid exchange. Line shape analysis of the 31 P{ 1 H} NMR spectra of 1-Cl over the À55 8C-+ 22 8C temperature range followed by an Eyring analysis afforded DH°= + 16.7 (AE 0.9) kcal mol À1 and DS°= + 16.6(AE3.8) cal mol À11 K À11 , suggesting a dissociative exchange of the phosphine arms. The ESI mass spectrum of this complex shows a peak at m/z 1101.1180 amu corresponding to the [LAu] + ion. A final clarification of the structure of this compound was derived from a single-crystal diffraction study which confirmed the coordination of two of the phosphorus atoms to the gold chloride fragment (Figure 1). [11] Inspection of the P-Au-P and P-Au-Cl angles (AE = 359.468) shows that these prima...

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“…The phosphinylstibine ligand (o-(PPh 2 )C 6 H 4 )SbCl 2 (L Cl )w as prepared by ar edistribution reaction between ((o-(PPh 2 )C 6 H 4 ) 3 Sb [10] and two equivalents of SbCl 3 (Scheme 1). This molecule, which was previously generated as an intermediate in the synthesis of (o-(PPh 2 )C 6 H 4 )Sb(C 6 F 5 ) 2 , [11] has now been isolated and fully characterized.…”

Section: Synthesis and Characterization Of Ap Hosphine-dichloroarylstmentioning

confidence: 99%

“…Antimony compounds should be handled cautiously:( tht)AuCl, [34] (o-(Ph 2 P)C 6 H 4 ) 3 Sb [10] ,a nd (o-(Ph 2 P)C 6 H 4 )SbPh 2 (L Ph ) [14] were prepared according to previously reported procedures. Solvents were dried by passing through an alumina column.…”

Section: Generalc Onsiderationsmentioning

confidence: 99%

Activation of an Au−Cl Bond by a Pendent Sb^III Lewis Acid: Impact on Structure and Catalytic Activity

Jones

Gabbaı̈

2016

Chemistry A European J

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With the objective of identifying new coordination modes of ambiphilic ligands, we have investigated the bidentate Sb/P ligands (o-(Ph P)C H )SbCl (L ) and (o-(Ph P)C H )SbPh (L ). Reaction of these ligands with (tht)AuCl affords the monoligated species L AuCl (1) and L AuCl (2), respectively, in which the antimony centers are only weakly engaged with the coordinated gold atom. Treatment of 1 with PPh induces an intramolecular transfer of a chloride ligand from gold to antimony to form the zwitterionic species o-(Cl Sb)C H (Ph P)Au(PPh ) (3). Natural bond orbital (NBO) calculations show that the antimony and gold centers are involved in weak Sb→Au and Au→Sb interactions, the latter reflecting the Lewis acidity of the pendent antimony group. Finally, we demonstrate that the ability of the antimony center in 1 to abstract a gold-bound chloride in the presence of a Lewis basic substrate may be utilized to activate the gold center for the electrophilic cycloisomerization of propargylic amides.

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Anomalous ligand field effects in complexes of quadridentate ligands containing group V donors

Cited by 33 publications

References 12 publications

Two‐Electron Redox Chemistry and Reversible Umpolung of a Gold–Antimony Bond

Two‐Electron Redox Chemistry and Reversible Umpolung of a Gold–Antimony Bond

Two‐Electron Redox Chemistry and Reversible Umpolung of a Gold–Antimony Bond

Activation of an Au−Cl Bond by a Pendent Sb^III Lewis Acid: Impact on Structure and Catalytic Activity

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Anomalous ligand field effects in complexes of quadridentate ligands containing group V donors

Cited by 33 publications

References 12 publications

Two‐Electron Redox Chemistry and Reversible Umpolung of a Gold–Antimony Bond

Two‐Electron Redox Chemistry and Reversible Umpolung of a Gold–Antimony Bond

Two‐Electron Redox Chemistry and Reversible Umpolung of a Gold–Antimony Bond

Activation of an Au−Cl Bond by a Pendent SbIII Lewis Acid: Impact on Structure and Catalytic Activity

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Activation of an Au−Cl Bond by a Pendent Sb^III Lewis Acid: Impact on Structure and Catalytic Activity