A Paramagnetic Diniobium Complex with a Very Short Nb−Nb Distance: Evidence for a Pseudo Nb−Nb Triple Bond?

Tayebani, Maryam; Feghali, Khalil; Gambarotta, Sandro; Yap, Glenn P. A.; Thompson, Laurence K.

doi:10.1002/(sici)1521-3773(19991216)38:24<3659::aid-anie3659>3.0.co;2-z

Cited by 20 publications

(14 citation statements)

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“…It should also be noted that contributions of zero-field splitting and spin−orbit coupling have been omitted to simplify analysis; complicated models employing these factors for magnetically related Ni(II) systems, however, have been examined . Although many reports exist on the magnetic behavior of vanadium-containing species, − there is little data on low-valent niobium-containing dimers other than those in which Nb−Nb bonds are suggested . Our primary interest lies in the comparison of the magnetic nature of 1 and 2 and the structural differences these data imply.…”

Section: Resultsmentioning

confidence: 99%

Macrocyclic Complexes of Niobium(III): Synthesis, Structure, and Magnetic Behavior of Mononuclear and Dinuclear Species That Incorporate the [P₂N₂] System

et al. 2001

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The coordination chemistry of the two mixed donor macrocyclic ligands R [P 2 N 2 ] (where R [P 2 N 2 ] ) RP(CH 2 SiMe 2 NSiMe 2 CH 2 ) 2 PR, R ) cyclohexyl (Cy) or phenyl (Ph)) with niobium-(III) is presented. The reaction of the dilithio precursors R [P 2 N 2 ]Li 2 (S) (R ) Cy, S ) THF; R ) Ph, S ) 1,4-dioxane) with NbCl 3 (DME) (DME ) 1,2-dimethoxyethane) generates the complexes R [P 2 N 2 ]NbCl (R ) Cy, 1; R ) Ph, 2). For R ) Cy, single-crystal X-ray diffraction studies and variable-temperature magnetic susceptibility measurements indicate that 1 is mononuclear in the solid state; however, analogous variable-temperature magnetic data suggest that 2 is dinuclear in the solid state due to the observation of antiferromagnetic exchange. In solution, 2 is apparently monomeric similar to 1. Adduct formation between these mononuclear complexes is also evident; reaction of 2 with neutral donors and coordinating solvents produces the mononuclear derivatives Ph [P 2 N 2 ]NbCl(L) (L ) py, CO, PMe 3 , THF, MeCN), of which the pyridine adduct, 3e, has been characterized crystallographically. Subsequent replacement of the chlorides can be achieved to generate the paramagnetic alkyl complexes R [P 2 N 2 ]NbR′ (R ) Cy, Ph; R′ ) CH 2 SiMe 3 , CH(SiMe 3 ) 2 ). The representative compounds Cy [P 2 N 2 ]NbCH 2 SiMe 3 (4a) and Ph [P 2 N 2 ]NbCH(SiMe 3 ) 2 (5b) have been characterized by X-ray crystallography.

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Section: Resultsmentioning

confidence: 99%

Macrocyclic Complexes of Niobium(III): Synthesis, Structure, and Magnetic Behavior of Mononuclear and Dinuclear Species That Incorporate the [P₂N₂] System

et al. 2001

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“…8 Of the transition metal complexes of 7-azaindole reported to date, the majority incorporate multiple metal centers in bridging or direct M-M bonding motifs. 9-17 For those complexes that contain only a single transition metal ion, coordination of the 7-azaindole primarily occurs through the pyridine N7 atom. 18-28 In very few instances have transition metal complexes featuring exclusive κ 1 -N1 coordination been reported, 29-31 although this coordination mode is better established for main group metals such as aluminum.…”

Section: Introductionmentioning

confidence: 99%

Homoleptic Transition Metal Complexes of the 7-Azaindolide Ligand Featuring κ¹-N1 Coordination

et al. 2015

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Homoleptic complexes of the anion of 7-azaindole (AzaIn) have been synthesized and characterized for a series of 3d transition metals. For Mn(II), Fe(II), and Co(II), complexes of formula Na2[M(AzaIn)4]·2L (L = THF, 2-MeTHF, toluene, or benzene) have been isolated by treatment of the corresponding metal chloride salts with 7-azaindole in the presence of sodium hexamethyldisilazide. The complexes adopt tetrahedral geometries with exclusive coordination to the transition metal ion through the pyrrolic N1 nitrogen atoms of the AzaIn ligands. Solid-state structures of the complexes demonstrate that the sodium cations remain tightly associated to the coordination entities through interaction with both the pyrrolic and pyridine nitrogen atoms of the azaindolide ligands. For Fe(II), replacement of the sodium cations by other alkali metal ions (Li or K) generates new complexes that demonstrate similar coordination geometries to the sodium salts. As a means of comparison, the Fe(II) complex of 4-azaindolide was also investigated. Na2[Fe(4-AzaIn)4]·2L adopts a similar solution structure to the 7-azaindolide complexes as judged by NMR spectroscopy and cyclic voltammetry. DFT calculations have been performed to investigate the bonding in the 7-azaindolide complexes. Results demonstrate that 7-azaindolide-κ1-N1 is a nearly pure sigma donor ligand that features a high degree of ionic character in its bonding to mid 3d transition metal ions.

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“…The discovery that transition metal compounds in which the metallic centers are joined by direct metalmetal bonding was one of the most revolutionary achievements of modern transition metal chemistry 1. The fact that undoubtedly underlines the importance of this discovery is that the corresponding bonds not only can often have the character of multiple bonds2–16 but also that usual limits of multiplicity known from organic chemistry can be exceeded. An example in this respect is the existence of the molecules containing quadruple metalmetal bonding 5, 6, 11, 12, 16, 17.…”

Section: Introductionmentioning

confidence: 99%

Chemical structures from the analysis of domain‐averaged Fermi holes: Multiple metalmetal bonding in transition metal compounds

2003

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The recently proposed approach based on the analysis of domain-averaged Fermi holes was applied to the study of the nature of metal-metal bonding in transition metal complexes and clusters. The main emphasis was put on the scrutiny of the systems assumed to contain direct multiple metal-metal bonds. The studied systems involve: (1) systems of the type M(2)X(6) (M = Mo, W, X = CH(3)) anticipated to contain metal-metal triple bonds; (2) the molecule of W(2)Cl(8) ((4-)) as the representative of the systems with quadruple metal-metal bonding; (3) diatomic molecules Mo(2) and V(2) considered as the potential candidates for higher than quadruple metal-metal bonding. Although the resulting picture of bonding has been usually shown to agree with the original expectations based on early simple MO models, some examples were also found in which the conclusions of the reported analysis display dramatic sensitivity to the quality of the wave function used for the generation of the Fermi holes. In addition to this we also report some examples where the original theoretical predictions of multiplicity of metal-metal bonds have to be corrected.

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A Paramagnetic Diniobium Complex with a Very Short Nb−Nb Distance: Evidence for a Pseudo Nb−Nb Triple Bond?

Cited by 20 publications

References 2 publications

Macrocyclic Complexes of Niobium(III): Synthesis, Structure, and Magnetic Behavior of Mononuclear and Dinuclear Species That Incorporate the [P₂N₂] System

Macrocyclic Complexes of Niobium(III): Synthesis, Structure, and Magnetic Behavior of Mononuclear and Dinuclear Species That Incorporate the [P₂N₂] System

Homoleptic Transition Metal Complexes of the 7-Azaindolide Ligand Featuring κ¹-N1 Coordination

Chemical structures from the analysis of domain‐averaged Fermi holes: Multiple metalmetal bonding in transition metal compounds

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A Paramagnetic Diniobium Complex with a Very Short Nb−Nb Distance: Evidence for a Pseudo Nb−Nb Triple Bond?

Cited by 20 publications

References 2 publications

Macrocyclic Complexes of Niobium(III): Synthesis, Structure, and Magnetic Behavior of Mononuclear and Dinuclear Species That Incorporate the [P2N2] System

Macrocyclic Complexes of Niobium(III): Synthesis, Structure, and Magnetic Behavior of Mononuclear and Dinuclear Species That Incorporate the [P2N2] System

Homoleptic Transition Metal Complexes of the 7-Azaindolide Ligand Featuring κ1-N1 Coordination

Chemical structures from the analysis of domain‐averaged Fermi holes: Multiple metalmetal bonding in transition metal compounds

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Macrocyclic Complexes of Niobium(III): Synthesis, Structure, and Magnetic Behavior of Mononuclear and Dinuclear Species That Incorporate the [P₂N₂] System

Macrocyclic Complexes of Niobium(III): Synthesis, Structure, and Magnetic Behavior of Mononuclear and Dinuclear Species That Incorporate the [P₂N₂] System

Homoleptic Transition Metal Complexes of the 7-Azaindolide Ligand Featuring κ¹-N1 Coordination