A hybrid carbocyclic/N-heterocyclic carbene ligand

Jandl, Christian; Pöthig, Alexander

doi:10.1039/c6cc08468k

Cited by 9 publications

(13 citation statements)

References 38 publications

(60 reference statements)

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“…The coordination of both carbene moieties also deviates from the ideal geometries and can be quantified by the NHC tilting angle Â NHC , defined by Luy et al (2015) as the angle between the metal atom, the carbene C atom and the centroid of the NHC, and the analogous Â CHT angle (Jandl & Pö thig, 2017), where 180 represents the ideal geometry in both cases. The values of Â NHC = 168.02 versus Â CHT = 176.76 show that the coordination geometry of the NHC is considerably more distorted than that of the CHT ligand and, in both cases, inplane ('yawing') displacement of the metal accounts for the major part of the distortion.…”

Section: Resultsmentioning

confidence: 99%

“…Compound (1) was synthesized according to our previously published procedure (Jandl & Pö thig, 2017). Dry solvents were obtained from an MB-SPS (MBraun) and stored over molecular sieves.…”

Section: Synthesis and Crystallizationmentioning

confidence: 99%

“…1 H NMR data are reported as follows: chemical shift in ppm [multiplicity (d = doublet, t = triplet and m = multiplet), coupling constant in Hz, integral, assignment]. Compound (1) was synthesized according to our previously published procedure (Jandl & Pö thig, 2017). ISSN 2053ISSN -2296 # 2017 International Union of Crystallography For the synthesis of compound (2), (1) (46 mg, 0.079 mmol, 1 equiv.)…”

Section: Synthesis and Crystallizationmentioning

confidence: 99%

“…The lesser-known class of carbocyclic carbene ligands is related to the class of NHCs in many respects (Ö fele et al, 2009) and has even been shown to have similar potential in catalytic applications (Herrmann et al, 2006). Recently, we have combined these two carbene types in a hybrid CHT (cycloheptatrienylidene)/NHC ligand (Jandl & Pö thig, 2017). In studies of the CHT/NHC-PdBr 2 complex (1) (see Scheme 1), we found a surprising reactivity towards iodine, resulting in the removal of one bromide ligand and dimerization of the complex, which shall be discussed in this article.…”

Section: Introductionmentioning

confidence: 99%

“…Jandl & Pö thig, 2017), so the excess of iodine leads to dimerization already in solution and not only upon crystallization. For the identity of the counter-ions in solution, we propose a mixture of different Br/I interhalides.…”

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confidence: 99%

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Dimerization of a mixed-carbene Pd^II dibromide complex by elemental iodine

Jandl

Pöthig

2017

Acta Crystallogr C Struct Chem

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A monomeric Pd complex bearing a mixed carbocyclic/N-heterocyclic carbene ligand and two bromides was reacted with an excess of elemental iodine, which resulted in the surprising removal of one bromide ligand and dimerization of the mixed-carbene complex to form di-μ-bromido-bis{[1-(cyclohepta-2,4,6-trien-2-yl-1-ylidene-κC)-3-(2,6-diisopropylphenyl)imidazol-2-ylidene]palladium(II)} bis(pentaiodide) dichloromethane monosolvate, [PdBr(CHN)](I)·CHCl. The dimeric complex features a slightly distorted square-planar core of two Pd centres bridged by two bromide ligands, which lie in the same plane as the seven- and five-membered rings of the bidentate carbene ligand. The counter-ions in the single crystal were found to be pentaiodide monoanions featuring their typical V-shape, whereas for the bulk material, a mixture of Br/I interhalides is proposed.

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Section: Resultsmentioning

confidence: 99%

“…Compound (1) was synthesized according to our previously published procedure (Jandl & Pö thig, 2017). Dry solvents were obtained from an MB-SPS (MBraun) and stored over molecular sieves.…”

Section: Synthesis and Crystallizationmentioning

confidence: 99%

Section: Synthesis and Crystallizationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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Dimerization of a mixed-carbene Pd^II dibromide complex by elemental iodine

Jandl

Pöthig

2017

Acta Crystallogr C Struct Chem

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Chasing C,C‐Palladacycles

Garcı́a-López

Saura‐Llamas

2021

Eur J Inorg Chem

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The different approaches for the synthesis of C,C-palladacycles are reviewed in this manuscript. These species hold a bidentate ligand that chelates the Pd atom through two C-donor moieties. Their relevance is closely related to the fact that they are intermediates in many palladium-catalyzed transformations. Furthermore, some of them have been used as efficient catalyst in cross coupling reactions. The review is structured according to the different strategies that have been employed to achieve the synthesis of the C,C-palladacycle derivatives, starting with those involving one elemental step (such as the oxidative addition of strained CÀ C bonds to Pd(0) or the transmetalation reactions between organometallic reagents and Pd(II) precursors), and continuing with more complex processes, where at least two elementary steps of Pd chemistry are involved (for example, carbometalation of alkenes followed by a CÀ H activation process). A final section highlights some aspects of synthetic methodologies based on Pd catalysis in which one or several C,C-palladacyclic intermediates are involved.Lenarda et al. synthesized the first reported four-membered C,C-palladacycles 1 a and 1 b in 1972, [5] via the oxidative addition of 1,1,2,2-tetracyanocyclopropane to [Pd(PPh 2 R) 4 ] (R = Ph; Me) (Scheme 1). The reaction occurred with the CÀ C bond cleavage of the highly strained ring and oxidative addition of the two resulting fragments to Pd(0).

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Electronic and ligating properties of carbocyclic carbenes: A theoretical investigation

et al. 2018

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Carbocyclic carbenes (CCCs) are a class of nucleophilic carbenes which are very similar to N-heterocyclic carbenes (NHCs) in terms of their reactivity, but they do not contain a stabilizing heteroatom in their cyclic ring system. In this study, 17 representative known CCCs and 34 newly designed CCCs are evaluated using quantum chemical methods, and the results are compared in terms of their stability, nucleophilicity, and proton affinity (PA) parameters. The results are divided on the basis of ring size of the known and reported CCCs. The stability, nucleophilicity, PA, complexation energy, and bond strength-related parameters were estimated using M06/6-311 ++G(d,p) method. The results indicated that the CCCs known in the literature are strong σ-electron donating species and have considerable π-accepting properties. This study led to the design and identification of a few new CCCs with dimethylamine and diaminomethynyl substituents which can be singlet stable and are substantially nucleophilic.

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A hybrid carbocyclic/N-heterocyclic carbene ligand

Cited by 9 publications

References 38 publications

Dimerization of a mixed-carbene Pd^II dibromide complex by elemental iodine

Dimerization of a mixed-carbene Pd^II dibromide complex by elemental iodine

Chasing C,C‐Palladacycles

Electronic and ligating properties of carbocyclic carbenes: A theoretical investigation

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A hybrid carbocyclic/N-heterocyclic carbene ligand

Cited by 9 publications

References 38 publications

Dimerization of a mixed-carbene PdII dibromide complex by elemental iodine

Dimerization of a mixed-carbene PdII dibromide complex by elemental iodine

Chasing C,C‐Palladacycles

Electronic and ligating properties of carbocyclic carbenes: A theoretical investigation

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Product

Resources

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Dimerization of a mixed-carbene Pd^II dibromide complex by elemental iodine

Dimerization of a mixed-carbene Pd^II dibromide complex by elemental iodine