N2.3−: Filling a Gap in the N2n− Series

Kaim, Wolfgang; Sarkar, Biprajit

doi:10.1002/anie.200904968

Cited by 20 publications

(8 citation statements)

References 45 publications

(43 reference statements)

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“…A recent synthetic-spectroscopic-computational study has described the first definitive examples of N 2 3− complexes, using dysprosium and yttrium (Figure 8). lxi These μ−η 2 :η 2 bridging dinitrogen ligands have N-N bond distances near 1.40 Å. The assignment of N 2 3− is supported by EPR studies on the Y compounds that show hyperfine splitting consistent with an N 2 -based radical, and DFT studies that reproduce the N-N bond distance and stretching frequency.…”

Section: Binding With "Three-electron Reduction" and "Four-electron Rmentioning

confidence: 83%

Metal–dioxygen and metal–dinitrogen complexes: where are the electrons?

2010

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Transition-metal complexes of O2 and N2 play an important role in the environment, chemical industry, and metalloenzymes. This Perspective compares and contrasts the binding modes, reduction levels, and electronic influences on the nature of the bound O2 or N2 group in these complexes. The charge distribution between the metal and the diatomic ligand is variable, and different models for describing the adducts have evolved. In some cases, single resonance structures (e.g. M-superoxide = M–O2−) are accurate descriptions of the adducts. Recent studies have shown that the magnetic coupling in certain N22− complexes differs between resonance forms, and can be used to distinguish experimentally between resonance structures. On the other hand, many O2 and N2 complexes cannot be described well with a simple valence-bond model. Defining the situations where ambiguities occur is a fertile area for continued study.

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Section: Binding With "Three-electron Reduction" and "Four-electron Rmentioning

confidence: 83%

Metal–dioxygen and metal–dinitrogen complexes: where are the electrons?

2010

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“…Odd-electron nitrogen oxidation states, instead, propose radical character and one-electron reduction mechanisms, but have not been observed in Chatt or Schrock cycles so far. However, this potential intermediacy of [N 2 ] ·– or [N 2 ] 3·– radical ions in metal complexes proved existence only very recently in dinuclear nickel, iron, and lanthanide complexes, respectively. ,− Thereby, [N 2 ] ·– were found to exhibit N–N bond lengths of about 1.13–1.18 Å and N–N stretching frequencies of 1740–1950 cm –1 , ,− ,, whereas the d NN in [N 2 ] 3·– ions was found to be at 1.39–1.41 Å with shifted N–N stretching energies of below 1000 cm –1 . − To gain final evidence for the presence of such radical anions [N 2 ] ·– or [N 2 ] 3·– , electron spin resonance spectroscopy (ESR) revealed clearly visible signals in accordance with simulated spectra indicative of unpaired electrons and supporting the radical formulation of dinitrogen ligation. ,, …”

Section: Introductionmentioning

confidence: 99%

High-Pressure Synthesis and Characterization of Li₂Ca₃[N₂]₃—An Uncommon Metallic Diazenide with [N₂]^2–Ions

Schneider

Seibald

Deringer³

et al. 2013

J. Am. Chem. Soc.

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Dinitrogen (N2) ligation is a common and well-characterized structural motif in bioinorganic synthesis. In solid-state chemistry, on the other hand, homonuclear dinitrogen entities as structural building units proved existence only very recently. High-pressure/high-temperature (HP/HT) syntheses have afforded a number of binary diazenides and pernitrides with [N2](2–) and [N2](4–) ions, respectively. Here, we report on the HP/HT synthesis of the first ternary diazenide. Li2Ca3[N2]3 (space group Pmma, no. 51, a = 4.7747(1), b = 13.9792(4), c = 8.0718(4) Å, Z = 4, wRp = 0.08109) was synthesized by controlled thermal decomposition of a stoichiometric mixture of lithium azide and calcium azide in a multianvil device under a pressure of 9 GPa at 1023 K. Powder X-ray diffraction analysis reveals strongly elongated N–N bond lengths of dNN = 1.34(2)–1.35(3) Å exceeding those of previously known, binary diazenides. In fact, the refined N–N distances in Li2Ca3[N2]3 would rather suggest the presence of [N2](3·–) radical ions. Also, characteristic features of the N–N stretching vibration occur at lower wavenumbers (1260–1020 cm(–1)) than in the binary phases, and these assignments are supported by first-principles phonon calculations. Ultimately, the true character of the N2 entity in Li2Ca3[N2]3 is probed by a variety of complementary techniques, including electron diffraction, electron spin resonance spectroscopy (ESR), magnetic and electric conductivity measurements, as well as density-functional theory calculations (DFT). Unequivocally, the title compound is shown to be metallic containing diazenide [N2](2–) units according to the formula (Li(+))2(Ca(2+))3([N2](2–))3·(e(–))2.

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“…The (N 2 ) 3− radical was recently synthesized for the first time in complexes of dysprosium and yttrium, Schemes and . Although (N 2 ) 3− is isoelectronic with the well-known (O 2 ) − superoxide ion and dinitrogen reduction has been heavily studied, − this oxidation level of reduced dinitrogen had remained elusive for decades. Density functional theory (DFT) studies on the complex of the closed shell Y 3+ ion indicated that the unpaired spin density in the (N 2 ) 3− radical was located in an orbital perpendicular to the metal orbitals and the isolation of this reactive species may be facilitated by the ionic nature of Dy 3+ and Y 3+ …”

Section: Introductionmentioning

confidence: 99%

(N₂)³⁻ Radical Chemistry via Trivalent Lanthanide Salt/Alkali Metal Reduction of Dinitrogen: New Syntheses and Examples of (N₂)²⁻ and (N₂)³⁻ Complexes and Density Functional Theory Comparisons of Closed Shell Sc³⁺, Y³⁺, and Lu³⁺ versus 4f⁹ Dy³⁺

et al. 2011

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New syntheses of complexes containing the recently discovered (N(2))(3-) radical trianion have been developed by examining variations on the LnA(3)/M reductive system that delivers "LnA(2)" reactivity when Ln = scandium, yttrium, or a lanthanide, M = an alkali metal, and A = N(SiMe(3))(2) and C(5)R(5). The first examples of LnA(3)/M reduction of dinitrogen with aryloxide ligands (A = OC(6)R(5)) are reported: the combination of Dy(OAr)(3) (OAr = OC(6)H(3)(t)Bu(2)-2,6) with KC(8) under dinitrogen was found to produce both (N(2))(2-) and (N(2))(3-) products, [(ArO)(2)Dy(THF)(2)](2)(μ-η(2):η(2)-N(2)), 1, and [(ArO)(2)Dy(THF)](2)(μ-η(2):η(2)-N(2))[K(THF)(6)], 2a, respectively. The range of metals that form (N(2))(3-) complexes with [N(SiMe(3))(2)](-) ancillary ligands has been expanded from Y to Lu, Er, and La. Ln[N(SiMe(3))(2)](3)/M reactions with M = Na as well as KC(8) are reported. Reduction of the isolated (N(2))(2-) complex {[(Me(3)Si)(2)N](2)Y(THF)}(2)(μ-η(2):η(2)-N(2)), 3, with KC(8) forms the (N(2))(3-) complex, {[(Me(3)Si)(2)N](2)Y(THF)}(2)(μ-η(2):η(2)-N(2))[K(THF)(6)], 4a, in high yield. The reverse transformation, the conversion of 4a to 3 can be accomplished cleanly with elemental Hg. The crown ether derivative {[(Me(3)Si)(2)N](2)Y(THF)}(2)(μ-η(2):η(2)-N(2))[K(18-crown-6)(THF)(2)] was isolated from reduction of 3 with KC(8) in the presence of 18-crown-6 and found to be much less soluble in tetrahydrofuran (THF) than the [K(THF)(6)](+) salt, which facilitates its separation from 3. Evidence for ligand metalation in the Y[N(SiMe(3))(2)](3)/KC(8) reaction was obtained through the crystal structure of the metallacyclic complex {[(Me(3)Si)(2)N](2)Y[CH(2)Si(Me(2))NSiMe(3)]}[K(18-crown-6)(THF)(toluene)]. Density functional theory previously used only with reduced dinitrogen complexes of closed shell Sc(3+) and Y(3+) was extended to Lu(3+) as well as to open shell 4f(9) Dy(3+) complexes to allow the first comparison of bonding between these four metals.

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N₂^.3−: Filling a Gap in the N₂ⁿ⁻ Series

Cited by 20 publications

References 45 publications

Metal–dioxygen and metal–dinitrogen complexes: where are the electrons?

Metal–dioxygen and metal–dinitrogen complexes: where are the electrons?

High-Pressure Synthesis and Characterization of Li₂Ca₃[N₂]₃—An Uncommon Metallic Diazenide with [N₂]^2–Ions

(N₂)³⁻ Radical Chemistry via Trivalent Lanthanide Salt/Alkali Metal Reduction of Dinitrogen: New Syntheses and Examples of (N₂)²⁻ and (N₂)³⁻ Complexes and Density Functional Theory Comparisons of Closed Shell Sc³⁺, Y³⁺, and Lu³⁺ versus 4f⁹ Dy³⁺

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N2.3−: Filling a Gap in the N2n− Series

Cited by 20 publications

References 45 publications

Metal–dioxygen and metal–dinitrogen complexes: where are the electrons?

Metal–dioxygen and metal–dinitrogen complexes: where are the electrons?

High-Pressure Synthesis and Characterization of Li2Ca3[N2]3—An Uncommon Metallic Diazenide with [N2]2–Ions

(N2)3− Radical Chemistry via Trivalent Lanthanide Salt/Alkali Metal Reduction of Dinitrogen: New Syntheses and Examples of (N2)2− and (N2)3− Complexes and Density Functional Theory Comparisons of Closed Shell Sc3+, Y3+, and Lu3+ versus 4f9 Dy3+

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N₂^.3−: Filling a Gap in the N₂ⁿ⁻ Series

High-Pressure Synthesis and Characterization of Li₂Ca₃[N₂]₃—An Uncommon Metallic Diazenide with [N₂]^2–Ions

(N₂)³⁻ Radical Chemistry via Trivalent Lanthanide Salt/Alkali Metal Reduction of Dinitrogen: New Syntheses and Examples of (N₂)²⁻ and (N₂)³⁻ Complexes and Density Functional Theory Comparisons of Closed Shell Sc³⁺, Y³⁺, and Lu³⁺ versus 4f⁹ Dy³⁺