Hydroelementation of Unsaturated C–C Bonds Catalyzed by Metal Scorpionate Complexes

Wathier, Matthew; Love, Jennifer A.

doi:10.1002/ejic.201501272

Cited by 25 publications

(12 citation statements)

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“…Intramolecular hydrophosphination of alkynes catalyzed by trivalent lanthanides was reported 15 years ago by Marks et al − The first intermolecular version using divalent lanthanides followed soon thereafter . Ever since, there is an increasing interest in the hydrophosphination catalyzed by di- and trivalent lanthanide complexes. − The recent development was covered by some review articles. − …”

Section: Introductionmentioning

confidence: 99%

Homoleptic Chiral Benzamidinate Complexes of the Heavier Alkaline Earth Metals and the Divalent Lanthanides

Gamer

Roesky

2016

Organometallics

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Reaction of the chiral amidine N,N′-bis(1-phenylethyl)benzamidine ((S)-HPEBA), KCH(SiMe3)2, and MI2 (M = Ca, Sr, Ba) or LnI2 (Ln = Eu, Yb) in a 2:2:1 stoichiometric ratio resulted in the chiral homoleptic monomeric alkaline earth metal compounds [Ca(PEBA)2(THF)2] (1) and [Sr(PEBA)2(THF)2] (2), the dimeric barium complex [Ba(PEBA)2]2 (3), and the monomeric divalent lanthanide compounds [Eu(PEBA)2(THF)2] (4), and [Yb(PEBA)2(THF)2] (5). The solid-state structures of all compounds were established by single-crystal X-ray diffraction. Three different structures are observed in the solid state. Compounds 1, 2, 4, and 5 form distorted coordination octahedra. For the alkaline earth element complexes 1 and 2, the two THF molecules are located in a trans-position, whereas, for the lanthanide compounds 4 and 5, they are arranged in a cis-position. In contrast, the barium complex 3 is dimeric with two amidinate ligands in an unusual “side-on” bridging mode. All five complexes were used as catalysts for hydrophosphination reactions of styrene and substituted analogues.

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Section: Introductionmentioning

confidence: 99%

Homoleptic Chiral Benzamidinate Complexes of the Heavier Alkaline Earth Metals and the Divalent Lanthanides

Gamer

Roesky

2016

Organometallics

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“…magnets. 10,11,12 Other promising application fields of pyrazolylborate complexes are catalysis 13,14,15,16,17 and the incorporation into polymers, 18 dendrimers, 19 molecular machines, 20 and metal-organic frameworks. 21 From the very first, these compounds have been studied by using paramagnetic NMR spectroscopy (pNMR) 1,22,23,24 and the initial results have been compiled.…”

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confidence: 99%

Paramagnetic Pyrazolylborate Complexes Tp₂M and Tp*₂M: ¹H, ¹³C, ¹¹B, and ¹⁴N NMR Spectra and First-Principles Studies of Chemical Shifts

et al. 2020

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Paramagnetic pyrazolylborates Tp2M and Tp*2M (M = Cu, Ni, Co, Fe, Mn, Cr, V) as well as [Tp2M] + and [Tp*2M] +(M = Fe, Cr, V) have been synthesized and their NMR spectra recorded. The 1 H signal shift ranges vary from ~30 ppm [Cu(II) and V(III)] to ~220 ppm [Co(II)] and the 13 C signal shift ranges from ~180 ppm [Fe(III)] to ~1150 ppm [Cr(II)]. The 11 B and 14 N shifts are ~360 ppm and ~730 ppm, respectively. Both negative and positive shifts have been observed for all nuclei. The narrow NMR signals of the Co(II), Fe(II), Fe(III), and V(III) derivatives provide resolved 13 C, 1 H couplings. All chemical shifts have been calculated from first-principles calculations on a modern version of Kurland-McGarvey theory which includes optimized structures, zero-field splittingand g-tensors, as well as signal shift contributions. Temperature dependence in the Fe(II) spin-crossover complex results from the equilibrium of the ground singlet and the excited quintet. We illustrate both the assignment and analysis capabilities, as well as the shortcomings of the current computational methodology. magnets. 10,11,12 Other promising application fields of pyrazolylborate complexes are catalysis 13,14,15,16,17 and the incorporation into polymers, 18 dendrimers, 19 molecular machines, 20 and metal-organic frameworks. 21 From the very first, these compounds have been studied by using paramagnetic NMR spectroscopy (pNMR) 1,22,23,24 and the initial results have been compiled. 25 Note that in the early literature the signs of pNMR signal shifts are inverted. Subsequent work, which shall be referred to below, is based on those findings and usually limited to proton NMR of Fe(II), Co(II), and Ni(II) derivatives. For three Co(II) derivatives Rouf, Mareš, and Vaara have tested theoretical and computational methods of calculating molecular properties, e.g., 1 H pNMR parameters. 26 Clearly, pyrazolylborate derivatives of many other paramagnetic ions exist or are conceivable and, given the diversity of this chemistry, some general questions from a pNMR point of view emerge: Which TpM-type compounds are worth investigating? What are the most useful nuclei? At what theoretical level can the spectra be reproduced? Do the calculated signal shifts support the signal assignment and thus the determination of the molecular and electronic structure? How are the signal shifts composed? Along these lines we have studied the parent compounds (Figure 1a) Tp2M (M = Cu, Ni, Co, Fe, Mn, Cr, and V), their monocations [Tp2M] + (M = Fe, Cr, and V), the methylated analogues Tp*2M (Tp* = hydrotris(3,5-dimethylpyrazole)borate, M = Cu, Ni, Co, Fe, Mn, Cr, and V), and [Tp*2M] + (M = Fe, Cr, and V). The present paper reports the 1 H, 13 C, 11 B, and 14 N NMR spectral data and their theoretical interpretation. To this end, first-principles calculations according to the recently redressed version 27,28 of the Kurland-McGarvey theory 29 have been carried out. These computations provide the respective overall pNMR signal shifts and their tensorial components, as well as co...

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“…Transition metal‐catalyzed reactions involving nitrene transfer to alkenes have gained prominence in this regard , . Of these latter catalysts, copper(I) and silver(I) scorpionate complexes [tris(pyrazolyl)borates, (normal scorpionates, or Tp R , Scheme , top left), tris(pyrazolyl)methanes (Tpm R or C ‐scorpionates, Scheme , top right), certain C‐heteroscorpionates (Scheme , bottom left), and certain nitrogen‐confused C‐scorpionates (Scheme , bottom right)] have proven adept at catalytically affording aziridines from alkenes and various nitrene sources under mild conditions. Thus, Pérez and co‐workers found that Tp*Cu(C 2 H 4 ), or other CuTp R complexes (prepared in‐situ) catalyze the aziridination of styrene, cyclooctene, or 1‐hexene over the course of a few hours at room temperature in CH 2 Cl 2 using PhI=NTs as a nitrene transfer agent.…”

Section: Introductionmentioning

confidence: 99%

Silver(I) and Copper(I) Complexes of Semi‐Bulky Nitrogen‐Confused C‐Scorpionates

et al. 2020

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Two new sterically demanding nitrogen-confused C-scorpionate ligands with a bis(3,5-diisopropylpyrazol-1yl)methyl group bound to the 3-position of a normal pyrazole ( H L iPr2 ) or an N-toluenesulfonyl pyrazole ( Ts L iPr2 ) have been prepared. Reactions between the ligands ( x L iPr2 ) and silver trifluoromethanesulfonate, AgOTf, gave four new compounds of the types [Ag(Ts, 1b; x = H, 2b) depending on the initial metal:ligand ratio. Similarly, the reactions with [Cu(CH 3 CN) 4 ](PF 6 ) produce [a] Dr.to trap and spectroscopically characterize the nitrene intermediates {[(2-py)Bpm R3R5 ]Cu(NTs)} + in CH 2 Cl 2 at -78°C using (2-tBuSO 2 )C 6 H 4 I=NTs [34] as a soluble nitrene source. The spectroscopic and magnetic data were consistent with diamagnetic, singlet species at -78°C. Calculations showed ground state triplet but all spin states [ 1/3 Cu I -nitrene or 1/3 Cu II -N·(iminyl)] and nitrene binding modes (κ 1 N-, κ 2 N,O-) are thermally accessible. These intermediates were capable of stoichiometrically transferring a nitrene unit to a variety of substrates. Then, different {[(2-py)Bpm R3R5 ]Cu(CH 3 CN)}(PF 6 ) complexes were found to be capable catalysts for nitrene transfer to unsubstituted or p-substituted styrenes giving modest yields (> 65 %) of aziridine under mild ocnditions (PhI=NTs/CH 2 Cl 2 /295 K, 24 h).In a previous study, [27] eight complexes of the type [Ag( x L R ) n ](OTf ) (n = 1, 2 and x L R = H L, Ts L, H L*, and Ts L*) were characterized and evaluated for their ability to catalyze aziridination of styrene. Both ESI(+) MS and NMR spectroscopic studies indicated that the analytically pure [Ag( x L R ) n ](OTf ) compounds did not retain their structure in CH 3 CN rather were involved in multiple dynamic equilibria in solution. These dynamic processes remained in the fast exchange regime on the NMR timescale down to the freezing point of the solvent, thereby obfuscating structural information. These silver complexes of nitrogen-confused C-scorpionates showed no or very little capacity to participate in styrene aziridination using PhI= NTs in room temperature CH 2 Cl 2 . However, [Ag( x L R ) n ](OTf ) showed modest catalytic activity at 80°C in CH 3 CN when employing a nitrene generated in-situ from H 2 NTs and PhI(OAc). Interestingly, the bulkiest derivative [Ag( Ts L * ) 2 ](OTf ) was reported to have the highest activity giving 34 % yield of the desired N-tosyl aziridine. This observation prompted the current study to determine if further increasing steric bulk of the ligands would lead to an increase in catalytic activity of silver complexes. Herein we report on the preparation of two new semi-bulky nitrogen confused scorpionates, Ts L iPr2 and H L iPr2 and their silver(I) and copper(I) complexes. The copper(I) complexes were prepared to compare catalytic activity with their silver congeners, and possibly to demonstrate the generality of any trends in ligand sterics on catalytic activity. It was also hoped that the slower ligand exchange rates associated with the smaller copper(I) compared ...

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Hydroelementation of Unsaturated C–C Bonds Catalyzed by Metal Scorpionate Complexes

Cited by 25 publications

References 123 publications

Homoleptic Chiral Benzamidinate Complexes of the Heavier Alkaline Earth Metals and the Divalent Lanthanides

Homoleptic Chiral Benzamidinate Complexes of the Heavier Alkaline Earth Metals and the Divalent Lanthanides

Paramagnetic Pyrazolylborate Complexes Tp₂M and Tp*₂M: ¹H, ¹³C, ¹¹B, and ¹⁴N NMR Spectra and First-Principles Studies of Chemical Shifts

Silver(I) and Copper(I) Complexes of Semi‐Bulky Nitrogen‐Confused C‐Scorpionates

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Hydroelementation of Unsaturated C–C Bonds Catalyzed by Metal Scorpionate Complexes

Cited by 25 publications

References 123 publications

Homoleptic Chiral Benzamidinate Complexes of the Heavier Alkaline Earth Metals and the Divalent Lanthanides

Homoleptic Chiral Benzamidinate Complexes of the Heavier Alkaline Earth Metals and the Divalent Lanthanides

Paramagnetic Pyrazolylborate Complexes Tp2M and Tp*2M: 1H, 13C, 11B, and 14N NMR Spectra and First-Principles Studies of Chemical Shifts

Silver(I) and Copper(I) Complexes of Semi‐Bulky Nitrogen‐Confused C‐Scorpionates

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Paramagnetic Pyrazolylborate Complexes Tp₂M and Tp*₂M: ¹H, ¹³C, ¹¹B, and ¹⁴N NMR Spectra and First-Principles Studies of Chemical Shifts