Field-induced slow magnetic relaxation in low-spin S = 1/2 mononuclear osmium(<scp>v</scp>) complexes

Su, Qian-Qian; Fan, Kebin; Huang, Xingyuan; Xiang, Jing; Cheng, Shun‐Cheung; Ko, Chi‐Chiu; Zheng, Li‐Min; Kurmoo, Mohamedally; Lau, Tai‐Chu

doi:10.1039/d0dt00295j

Cited by 20 publications

(22 citation statements)

References 79 publications

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“…On the other hand, the n values for 1 lie between 4.3 and 5.5 and fall into the range typical of metal ions with relaxation through optical and acoustic Raman-like process (n being equal to 9 for the Raman relaxation of Kramer ions) [12]. These n values are very close to those that were obtained for similar 5d-SIMs (Table 3) [24][25][26]. Table 3.…”

Section: Ac Magnetic Susceptibilitysupporting

confidence: 78%

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Field-Induced Single-Ion Magnet Phenomenon in Hexabromo- and Hexaiodorhenate(IV) Complexes

et al. 2020

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Two mononuclear ReIV complexes of general formula (PPh4)2[ReX6] [PPh4+ = tetraphenylphosphonium cation, X = Br (1) and I (2)] have been prepared and structurally and magnetically characterised. Both compounds crystallise in the triclinic system with space group Pī. Their structures are made up of hexahalorhenate(IV), [ReX6]2−, anions, and bulky PPh4+ cations. Each ReIV ion in 1 and 2 is six-coordinate and bonded to six halide ions in a quasi regular octahedral geometry. In their crystal packing, the [ReX6]2− anions are well separated from each other through the organic cations, generating alternated anionic and cationic layers, and no intermolecular Re−X···X−Re interactions are present. Variable-temperature dc magnetic susceptibility measurements performed on microcrystalline samples of 1 and 2 show a very similar magnetic behaviour, which is typical of noninteracting mononuclear ReIV complexes with S = 3/2. Ac magnetic susceptibility measurements reveal the slow relaxation of the magnetisation in the presence of external dc fields for 1 and 2, hence indicating the occurrence of the field-induced single-ion magnet (SIM) phenomenon in these hexabromo- and hexaiodorhenate(IV) complexes.

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Section: Ac Magnetic Susceptibilitysupporting

confidence: 78%

“…These last systems complete the short list of SIMs that are based on the highly anisotropic Re IV metal ion. Recently, additional 5d-SIMs containing the Os V and Ir IV metal ions have also been reported [24][25][26].…”

Section: Introductionmentioning

confidence: 99%

Field-Induced Single-Ion Magnet Phenomenon in Hexabromo- and Hexaiodorhenate(IV) Complexes

et al. 2020

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“…[7] In analogy to WOC, intermediates featuring metal‐nitrogen multiple bonds (specifically, metal nitride (M≡N) and imide (M=NR) intermediates) have been proposed for several systems that mediate ammonia oxidation [3] . Furthermore, bimolecular nitride [3, 8] and imide [9] coupling, and the nucleophilic attack of amines on terminal imides [3, 10] and nitrides, [11] have been implicated in relevant N–N bond forming reactions.…”

Section: Figurementioning

confidence: 99%

Hydrazine Formation via Coupling of a Nickel(III)–NH₂ Radical

Oyala

Peters

2020

Angew Chem Int Ed

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M(NHx) intermediates involved in N−N bond formation are central to ammonia oxidation (AO) catalysis, an enabling technology to ultimately exploit ammonia (NH3) as an alternative fuel source. While homocoupling of a terminal amide species (M‐NH2) to form hydrazine (N2H4) has been proposed, well‐defined examples are without precedent. Herein, we discuss the generation and electronic structure of a NiIII‐NH2 species that undergoes bimolecular coupling to generate a NiII2(N2H4) complex. This hydrazine adduct can be further oxidized to a structurally unusual Ni2(N2H2) species; this releases N2 in the presence of NH3, thus establishing a synthetic cycle for Ni‐mediated AO. Distribution of the redox load for H2N‐NH2 formation via NH2 coupling between two metal centers presents an attractive strategy for AO catalysis using Earth‐abundant, late first‐row metals.

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“…11,12 In analogy to WOC, intermediates featuring metal-to-nitrogen multiple bonds (specifically, metal nitride and imide intermediates) have been proposed for several systems that mediate stoichiometric or catalytic ammonia oxidation. 3,4abd,5abd,6ab,8ac Furthermore, bimolecular nitride (M≡N) 4ab,5b, 13 and imide (M=NR) 14 coupling, and the nucleophilic attack of amines on terminal imides 5d,8a,15 and nitrides, 16…”

Section: Introductionmentioning

confidence: 99%

Hydrazine Formation via NiIII-NH2 Radical Coupling in Ni-Mediated Ammonia Oxidation

Gu¹,

Oyala²,

Peters

2020

Preprint

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Given the diverse mechanistic possibilities for the overall 6e-/6H+ transformation of ammonia to dinitrogen, identification of M(NHx) intermediates involved in N–N bond formation is a central mechanistic challenge. In analogy to water oxidation mechanisms, which widely invoke metal oxo intermediates, metal imide and nitride intermediates have commonly been proposed for ammonia oxidation, and stoichiometric demonstration of N–N bond formation from these metal-ligand multiply bonded species is well-precedented. In contrast, while the homocoupling of M–NH2 species to form hydrazine has been hypothesized as the key N–N bond forming step in certain molecular ammonia oxidation systems, well-defined examples of this transformation from M–NH2 complexes are essentially without precedent. This work reports the first example of net ammonia oxidation mediated by a molecular Ni species, a transformation carried out via formal NiII/NiIII oxidation states. The available data are consistent with a NiIII–NH2 intermediate featuring substantial spin at N undergoing N–N bond formation to generate a NiII2(N2H4) complex. Additional and structurally unusual Nix(NyHz) species – including a Ni2(trans-N2H2) complex – are characterized and studied as intermediates in the Ni-mediated ammonia oxidation cycle described herein.

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Field-induced slow magnetic relaxation in low-spin S = 1/2 mononuclear osmium(v) complexes

Abstract: Stable low-spin Os(v) complexes obtained from the photochemical reactions of NO2-OsN showing slow magnetic relaxation behavior.

Cited by 20 publications

References 79 publications

Field-Induced Single-Ion Magnet Phenomenon in Hexabromo- and Hexaiodorhenate(IV) Complexes

Field-Induced Single-Ion Magnet Phenomenon in Hexabromo- and Hexaiodorhenate(IV) Complexes

Hydrazine Formation via Coupling of a Nickel(III)–NH₂ Radical

Hydrazine Formation via NiIII-NH2 Radical Coupling in Ni-Mediated Ammonia Oxidation

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Field-induced slow magnetic relaxation in low-spin S = 1/2 mononuclear osmium(v) complexes

Abstract: Stable low-spin Os(v) complexes obtained from the photochemical reactions of NO2-OsN showing slow magnetic relaxation behavior.

Cited by 20 publications

References 79 publications

Field-Induced Single-Ion Magnet Phenomenon in Hexabromo- and Hexaiodorhenate(IV) Complexes

Field-Induced Single-Ion Magnet Phenomenon in Hexabromo- and Hexaiodorhenate(IV) Complexes

Hydrazine Formation via Coupling of a Nickel(III)–NH2 Radical

Hydrazine Formation via NiIII-NH2 Radical Coupling in Ni-Mediated Ammonia Oxidation

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Product

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Hydrazine Formation via Coupling of a Nickel(III)–NH₂ Radical