Dispersion Forces Drive the Formation of Uranium–Alkane Adducts

Jung, Jaehun; Löffler, Sascha T.; Langmann, Jan; Heinemann, Frank W.; Bill, Eckhard; Bistoni, Giovanni; Scherer, Wolfgang; Atanasov, Mihail; Meyer, Karsten; Neese, Frank

doi:10.1021/jacs.9b10620

Cited by 19 publications

(20 citation statements)

References 36 publications

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“…These solution-based techniques provide unequivocal evidence for alkane coordination at a metal center. However, their use for the subsequent isolation of a crystalline material that allows for detailed structural characterization using single-crystal X-ray diffraction, or onward reactivity studies, has yet to be realized. , This is because rapid alkane displacement by a solvent or a photogenerated ligand leads to lifetimes unsuitable for solution-based crystallization techniques, a situation compounded by the low temperatures used and less than 100% photoconversations achieved.…”

Section: Introductionmentioning

confidence: 99%

A Series of Crystallographically Characterized Linear and Branched σ-Alkane Complexes of Rhodium: From Propane to 3-Methylpentane

et al. 2021

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Using solid-state molecular organometallic (SMOM) techniques, in particular solid/gas single-crystal to single-crystal reactivity, a series of σ-alkane complexes of the general formula [Rh(Cy 2 PCH 2 CH 2 PCy 2 )(η n :η m -alkane)][BAr F 4 ] have been prepared (alkane = propane, 2-methylbutane, hexane, 3-methylpentane; Ar F = 3,5-(CF 3 ) 2 C 6 H 3 ). These new complexes have been characterized using single crystal X-ray diffraction, solid-state NMR spectroscopy and DFT computational techniques and present a variety of Rh(I)···H–C binding motifs at the metal coordination site: 1,2-η 2 :η 2 (2-methylbutane), 1,3-η 2 :η 2 (propane), 2,4-η 2 :η 2 (hexane), and 1,4-η 1 :η 2 (3-methylpentane). For the linear alkanes propane and hexane, some additional Rh(I)···H–C interactions with the geminal C–H bonds are also evident. The stability of these complexes with respect to alkane loss in the solid state varies with the identity of the alkane: from propane that decomposes rapidly at 295 K to 2-methylbutane that is stable and instead undergoes an acceptorless dehydrogenation to form a bound alkene complex. In each case the alkane sits in a binding pocket defined by the {Rh(Cy 2 PCH 2 CH 2 PCy 2 )} + fragment and the surrounding array of [BAr F 4 ] − anions. For the propane complex, a small alkane binding energy, driven in part by a lack of stabilizing short contacts with the surrounding anions, correlates with the fleeting stability of this species. 2-Methylbutane forms more short contacts within the binding pocket, and as a result the complex is considerably more stable. However, the complex of the larger 3-methylpentane ligand shows lower stability. Empirically, there therefore appears to be an optimal fit between the size and shape of the alkane and overall stability. Such observations are related to guest/host interactions in solution supramolecular chemistry and the holistic role of 1°, 2°, and 3° environments in metalloenzymes.

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Section: Introductionmentioning

confidence: 99%

A Series of Crystallographically Characterized Linear and Branched σ-Alkane Complexes of Rhodium: From Propane to 3-Methylpentane

et al. 2021

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“…The coordination chemistry of f-block metals supported by tripodal ligands has attracted considerable attention and resulted in new coordination modes and selective small molecule activation. − Most notably, Meyer and co-workers developed an arene-anchored tris(aryloxide) tripodal ligand system and showed that it can stabilize multiple oxidation states of f-block elements, including lanthanides and uranium, − as well as empowering redox catalysis. , In particular, the arene anchor of Meyer’s ligand played an important role in tuning the electronic structures at the metal centers. , Inspired by this work, we aimed to develop a tripodal tris(amido) ligand system with an arene anchor to combine the strong donating ability of amido ligands and the ambiphilic nature of the arene anchor. Despite the ubiquity of amido ligands in coordination chemistry, to the best of our knowledge, no example of tripodal-type tris(amido) ligands with an arene anchor has been reported.…”

Section: Introductionmentioning

confidence: 99%

Rare Earth Metal Complexes Supported by a Tripodal Tris(amido) Ligand System Featuring an Arene Anchor

et al. 2021

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A new tripodal tris(amido) ligand system featuring an arene anchor was developed and applied to the coordination chemistry of rare earth metals. Two tris(amido) ligands with a 1,3,5-triphenylbenzene backbone were prepared in two steps from commercially available reagents on a gram scale. Salt metathesis and alkane elimination reactions were exploited to prepare mononuclear rare earth metal complexes in moderate to good yields. For salt metathesis reactions, while metal tribromides yielded neutral metal tris(amido) complexes, metal trichlorides led to the formation of ate complexes with an additional chloride bound to the metal center. The new compounds were characterized by X-ray crystallography, elemental analysis, and 1H and 13C nuclear magnetic resonance spectroscopy. The rare earth metal complexes exhibit a trigonal planar coordination geometry for the [MN3] fragment in the solid state rather than a trigonal pyramidal geometry, commonly observed for rare earth metal tris(amido) complexes such as M[N(SiMe3)2]3. Moreover, the arene anchor of the tripodal ligands is engaged in a nonnegligible interaction with the rare earth metal ions. Density functional theory calculations were performed to gain insight into the bonding interactions between the tripodal ligands and the rare earth metal ions. While LUMOs of these rare earth metal complexes are mainly π* orbitals of the arene with a minor component of metal-based orbitals, HOMO–15 and HOMO–16 of a lanthanum complex show that the arene anchor serves as a π donor to the trivalent lanthanum ion.

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“…99 Finally, crystallographic evidence for η 2 -C,H coordination of an alkane to the uranium(III) tris(aryloxide) complex (( tBu,tBu ArO)3tacn)U (( R,R′ ArOH)3tacn = 1,4,7-tris((2-hydroxy-3-R-5-R′-phenyl)methyl)-1,4,7-triazacyclononane) was reported in 2003; 100 a more recent study attributed alkane binding to London dispersion interactions with the (( tBu,tBu ArO)3tacn) 3− ligand. 101…”

Section: Redox-neutral Adduct Formationmentioning

confidence: 99%