Rhodium(<scp>ii</scp>) dimers without metal–metal bonds

Zhu, Di; Sharma, Arzoo; Wiebe, C. R.; Budzelaar, Peter H. M.

doi:10.1039/c5dt02218e

Cited by 4 publications

(4 citation statements)

References 47 publications

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“…If hydrogenation of [4-COD][BAr F 4 ] is continued for a total of 30 min, decomposition to an, as yet unidentified, product(s) is observed upon dissolution in CD 2 Cl 2 , from which a featureless 31 P{ 1 H} NMR spectrum and a very broad 1 H NMR spectrum are observed. We speculate that this signals the formation of a paramagnetic Rh(II) dimeric complex on dissolution, but the identity of this species remains to be resolved. Attempts to obtain meaningful SSNMR data for [4-COA][BAr F 4 ] were hampered by temporal and temperature sensitivity that was amplified by the requirement to use finely crushed material for analysis by SSNMR that meant that crystallinity is lost much faster than for larger samples.…”

Section: Resultsmentioning

confidence: 99%

Modulation of σ-Alkane Interactions in [Rh(L₂)(alkane)]⁺ Solid-State Molecular Organometallic (SMOM) Systems by Variation of the Chelating Phosphine and Alkane: Access to η²,η²-σ-Alkane Rh(I), η¹-σ-Alkane Rh(III) Complexes, and Alkane Encapsulation

et al. 2018

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Solid/gas single-crystal to single-crystal (SC−SC) hydrogenation of appropriate diene precursors forms the corresponding σ-alkane complexes [Rh(Cy 2 P(CH 2 ) n PCy 2 )(L)]-[BAr F 4 ] (n = 3, 4) and [RhH(Cy 2 P(CH 2 ) 2 (CH)-(CH 2 ) 2 PCy 2 )(L)][BAr F 4 ] (n = 5, L = norbornane, NBA; cyclooctane, COA). Their structures, as determined by singlecrystal X-ray diffraction, have cations exhibiting Rh•••H−C σ-interactions which are modulated by both the chelating ligand and the identity of the alkane, while all sit in an octahedral anion microenvironment. These range from chelating η 2 ,η 2 Rh•••H−C (e.g., [Rh(Cy 2 P(CH 2 ) n PCy 2 )(η 2 η 2 -NBA)][BAr F 4 ], n = 3 and 4), through to more weakly bound η 1 Rh•••H−C in which C−H activation of the chelate backbone has also occurred (e.g., [RhH(Cy 2 P(CH 2 ) 2 (CH)(CH 2 ) 2 PCy 2 )(η 1 -COA)]-[BAr F 4 ]) and ultimately to systems where the alkane is not ligated with the metal center, but sits encapsulated in the supporting anion microenvironment, [Rh(Cy 2 P(CH 2 ) 3 PCy 2 )][COA⊂BAr F 4 ], in which the metal center instead forms two intramolecular agostic η 1 Rh•••H−C interactions with the phosphine cyclohexyl groups. CH 2 Cl 2 adducts formed by displacement of the η 1 -alkanes in solution (n = 5; L = NBA, COA), [RhH(Cy 2 P(CH 2 ) 2 (CH)(CH 2 ) 2 PCy 2 )(κ 1 -ClCH 2 Cl)][BAr F 4 ], are characterized crystallographically. Analyses via periodic DFT, QTAIM, NBO, and NCI calculations, alongside variable temperature solid-state NMR spectroscopy, provide snapshots marking the onset of Rh•••alkane interactions along a C−H activation trajectory. These are negligible in [Rh(Cy 2 P(CH 2 ) 3 PCy 2 )][COA⊂BAr F 4 ]; in [RhH(Cy 2 P(CH 2 ) 2 (CH)(CH 2 ) 2 PCy 2 )(η 1 -COA)][BAr F 4 ], σ C−H → Rh σ-donation is supported by Rh → σ* C−H "pregostic" donation, and in [Rh(Cy 2 P(CH 2 ) n PCy 2 )(η 2 η 2 -NBA)][BAr F 4 ] (n = 2−4), σ-donation dominates, supported by classical Rh(dπ) → σ* C−H π-back-donation. Dispersive interactions with the [BAr F 4 ] − anions and Cy substituents further stabilize the alkanes within the binding pocket.

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Section: Resultsmentioning

confidence: 99%

Modulation of σ-Alkane Interactions in [Rh(L₂)(alkane)]⁺ Solid-State Molecular Organometallic (SMOM) Systems by Variation of the Chelating Phosphine and Alkane: Access to η²,η²-σ-Alkane Rh(I), η¹-σ-Alkane Rh(III) Complexes, and Alkane Encapsulation

et al. 2018

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“…1) shows a monomeric T-shape complex (∠N1RhN3 = 94.08(10)°, ∠N2RhN3 = 175.39(11)°) in which the methine hydrogen of an i Pr group appears to occupy the fourth https://doi.org/10.1016/j.ica.2018.06.015 Received 13 April 2018; Received in revised form 7 June 2018; Accepted 8 June 2018 coordination site with an agostic interaction (d(Rh-H) 1.97(3) Å). Bond lengths within the (BDI)Rh fragment are similar to those of dimeric precursor complex 1 [5], and bond lengths within the anilide ring are similar to those in two of the three reported "innocent" platinum metal-NHdipp complexes [9], with the two ipso-ortho bonds slightly longer than the remaining ring bonds (≈1.42 vs ≈1.38 Å) [10,11]. The Rh-N (anilide) bond is short (1.937(3) Å) even compared to known Rh III anilide complexes (2.05-2.07 Å [12]) but falls within the narrow range of 1.93-1.97 Å reported for a series of (PNP)Rh II complexes where the amido group is part of a pincer ligand framework [13].…”

Section: Reaction Of 26-diisopropylanilidementioning

confidence: 67%

“…COSY and HSQC spectra were also acquired to assist 1 H and 13 C assignments. [(BDI)Rh] 2 (μ-Br) 2 was prepared according to a published procedure [5].…”

Section: Generalmentioning

confidence: 99%

“…We recently reported on the formation and characterization of the paramagnetic β-diiminate (BDI) rhodium bromide complex 1 and its iodide analog, which were found to contain paramagnetic Rh II centers without metal-metal bonds [5]. While the complexes are air-and moisture-sensitive, they did not display particularly high reactivity, possibly because dimer formation reduces coordinative unsaturation and results in steric shielding of the Rh centers.…”

Section: Introductionmentioning

confidence: 99%

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Reactivity of Rhodium(II) amido/Rhodium(I) aminyl complexes

Zhang

Zhu

Herbert

et al. 2018

Inorganica Chimica Acta

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Reaction of the Rh(II) dimer [LRh] 2 (μ-Br) 2 (L = ([2,6-Me 2 C 6 H 3 NCMe] 2 CH) with the bulky amide LiNH (2,6-i Pr 2 C 6 H 3) leads to a monomeric Rh(II) amide with a T-shape N 3 Rh arrangement and a pronounced agostic interaction. Reaction with the less bulky LiNH(2,6-Me 2 C 6 H 3) results in benzylic C-H activation to a binuclear complex with a unique aza-xylylene bridging mode. With LiNHC 6 H 5 we observe initial formation of [LRh] 2 (μ-NHPh) 2 followed by N,C2′ coupling of two anilines. These reactions can be explained based on aminyl radical character of the Rh(II) amides (supported by EPR evidence) and/or involvement of nitrene intermediates.

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Three Reversible Redox States of Thiolate-Bridged Dirhodium Complexes without Metal–Metal Bonds

Coll

Dunbar

2020

J. Am. Chem. Soc.

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An unusual dinuclear rhodium complex with the anionic 2-mercapto-6-methylpyridinate (mmp) bridging ligand is reported which is capable of undergoing significant variations in its structural and coordination environments as a result of two reversible redox events at accessible potentials (E 1/2 = 0.014, 0.52 V vs Ag/AgCl). The large degree of separation between these redox states (ΔE = 0.51 V, K C = 4.17 × 108) allows for the chemical isolation of three distinct complexes 1, 2, and 3, in which the oxidation states of each Rh center are Rh2 I,I, Rh2 I,II, and Rh2 II,II, respectively, and whose solid-state structures were elucidated by single crystal X-ray diffraction studies. Complex 2 is an unprecedented type of mixed valence dirhodium species whose electron paramagnetic resonance spectrum revealed a delocalization of the unpaired electron through the thiolate-bridging ligand. Intervalence charge transfer occurs between the Rh centers, as evidenced by a broad absorption in the near-infrared region (λmax = 1187 nm). The structure of 3 is quite rare in that it lacks the typical RhII–RhII σ bond, but significant orbital overlap between the Rh 4d z 2 and S 3p z orbitals results in a strong antiferromagnetic coupling (computed J = −1516.9 cm–1). Complex 3 also absorbs low-energy light (λmax = 779 nm). Spectroscopic and magnetic measurements are supported by density functional theory methods, which further elucidate the nature of the ground state energies, frontier orbital characters, excited state transitions, and presence of weak Rh–Rh natural bond orbital interactions.

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Rhodium(ii) dimers without metal–metal bonds

Cited by 4 publications

References 47 publications

Modulation of σ-Alkane Interactions in [Rh(L₂)(alkane)]⁺ Solid-State Molecular Organometallic (SMOM) Systems by Variation of the Chelating Phosphine and Alkane: Access to η²,η²-σ-Alkane Rh(I), η¹-σ-Alkane Rh(III) Complexes, and Alkane Encapsulation

Modulation of σ-Alkane Interactions in [Rh(L₂)(alkane)]⁺ Solid-State Molecular Organometallic (SMOM) Systems by Variation of the Chelating Phosphine and Alkane: Access to η²,η²-σ-Alkane Rh(I), η¹-σ-Alkane Rh(III) Complexes, and Alkane Encapsulation

Reactivity of Rhodium(II) amido/Rhodium(I) aminyl complexes

Three Reversible Redox States of Thiolate-Bridged Dirhodium Complexes without Metal–Metal Bonds

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Rhodium(ii) dimers without metal–metal bonds

Cited by 4 publications

References 47 publications

Modulation of σ-Alkane Interactions in [Rh(L2)(alkane)]+ Solid-State Molecular Organometallic (SMOM) Systems by Variation of the Chelating Phosphine and Alkane: Access to η2,η2-σ-Alkane Rh(I), η1-σ-Alkane Rh(III) Complexes, and Alkane Encapsulation

Modulation of σ-Alkane Interactions in [Rh(L2)(alkane)]+ Solid-State Molecular Organometallic (SMOM) Systems by Variation of the Chelating Phosphine and Alkane: Access to η2,η2-σ-Alkane Rh(I), η1-σ-Alkane Rh(III) Complexes, and Alkane Encapsulation

Reactivity of Rhodium(II) amido/Rhodium(I) aminyl complexes

Three Reversible Redox States of Thiolate-Bridged Dirhodium Complexes without Metal–Metal Bonds

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Modulation of σ-Alkane Interactions in [Rh(L₂)(alkane)]⁺ Solid-State Molecular Organometallic (SMOM) Systems by Variation of the Chelating Phosphine and Alkane: Access to η²,η²-σ-Alkane Rh(I), η¹-σ-Alkane Rh(III) Complexes, and Alkane Encapsulation

Modulation of σ-Alkane Interactions in [Rh(L₂)(alkane)]⁺ Solid-State Molecular Organometallic (SMOM) Systems by Variation of the Chelating Phosphine and Alkane: Access to η²,η²-σ-Alkane Rh(I), η¹-σ-Alkane Rh(III) Complexes, and Alkane Encapsulation