Dinitrogen and Related Chemistry of the Lanthanides: A Review of the Reductive Capture of Dinitrogen, As Well As Mono- and Di-aza Containing Ligand Chemistry of Relevance to Known and Postulated Metal Mediated Dinitrogen Derivatives

Gardiner, Michael G.; Stringer, Damien N.

doi:10.3390/ma3020841

Cited by 31 publications

(20 citation statements)

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“…Related studies with rare earth elements include the codeposition of the laser-ablated metals and N 2 gas in cryogenic matrices with a posteriori investigations by matrix-isolation IR spectroscopy [20][21][22][23]. Relevant compounds include various organometallic lanthanide dinitrogen complexes with fully characterised examples for the entire series of lanthanides [24][25][26][27].…”

Section: Introductionmentioning

confidence: 99%

“…The first quartet state ( 4 F 3/2 ) lies higher in energy by 2668 cm −1 and has an electron configuration of [Xe]4f 0 5d 2 6s 1 [32]. Here, the two singly occupied 5d orbitals can facilitate two orbital overlapping interactions in contrast to the single interaction by the doublet ground state.Description of the results will start with the analysis of the end-on complexes, because literature data on complexes of transition and rare earth metals with N 2 show generally the preference of this structure [12,[14][15][16][17][18][23][24][25][26][27][28]. Subsequently, the related side-on isomers will be discussed and compared with the end-on isomers.…”

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confidence: 99%

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Coordination of N2 ligands to lanthanum: the complexes La (N2)1–8

Kovács

2018

Struct Chem

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The structures and bonding properties of La(N 2 ) x (x = 1-8) complexes were investigated by density functional theory (DFT) computations using the B3LYP exchange-correlation functional in conjunction with a quasi-relativistic pseudopotential for La. The quality of the DFT electronic structures was confirmed in selected cases by relativistic multireference calculations using CASPT2 theory. From the end-on and side-on dinitrogen coordination modes in general, the structures with end-on coordination were found to be the more stable. The first coordination sphere of the complexes is filled by eight and six N 2 ligands in the end-on and side-on type species, respectively. The main bonding interaction is the donation of La 5d valence electrons to anti-bonding orbitals of N 2 resulting in characteristic elongation of the NN bonds. These directional interactions determine the (from steric point of view in several cases less logic) equilibrium molecular structures. The charge transfer resulted in partial charges up to 1.5 e of the originally neutral components (La, N 2 ) leading to electrostatic attractive interactions which compose the minor contribution in the bonding.Very recently, Zhao et al. studied the whole lanthanide series of Ln(N 2 ) molecules using the mPW3PBE hybrid exchange-correlation functional in conjunction with quasirelativistic 4f-in-valence pseudopotentials for the lanthanides and 6-31G* basis set for nitrogen [29]. The covered molecular properties were the geometries, HOMO-LUMO energy gaps, and magnetic and electronic properties. These calculations predicted the end-on 4 La(N 2 ) structure to be favoured by 47 kJ/mol over 2 La(N 2 ) with a side-on structure. From the bonding properties, the π-type HOMO orbital and the atomic charges were presented.Teng and Xu performed DFT calculations using the BP86 and B3LYP functionals in order to assist the interpretation of the matrix-isolation IR spectra of the reaction products formed by laser-ablated La co-deposited with N 2 [23]. In the spectra, several species were identified and their electronic structures, dissociation energies and vibrational data were reported. On the basis of isotope experiments and computed data, the authors concluded on the dominant presence of end-on 4 La(N 2 ) in the argon matrix.The only theoretical study on complexes of a lanthanide atom with more than one N 2 ligands is an early SCF/3-21G computational study of holmium complexes by Ermilov et al.[30] using a 4f-in-valence pseudopotential [31] for Ho. Beyond the low-quality computational level, this study has also other limitations: only quartet spin multiplicity and complexes up to six N 2 ligands were considered. However, the small energy difference between the quartet and sextet Ho [32] may readily be overcompensated by N 2 bonding, particularly in the larger complexes. Therefore, the sextet Ho(N 2 ) x species should not be neglected. (Note that Zhao et al., in contrast, studied only the sextet HoN 2 [29].) Most striking is, however, the instability of HoN 2 at the SCF/3-21G l...

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Section: Introductionmentioning

confidence: 99%

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confidence: 99%

Coordination of N2 ligands to lanthanum: the complexes La (N2)1–8

Kovács

2018

Struct Chem

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“…3 In particular, there are only three reported examples of CO 2 reduction and one example of CS 2 reduction mediated by complexes of lanthanides 4. The reduction of diazobenzene, an interesting model substrate for N 2 reduction, was also reported for Sm II complexes,2c but has never been observed for the less‐reducing Eu II complexes.…”

Section: Methodsmentioning

confidence: 91%

Tuning Lanthanide Reactivity Towards Small Molecules with Electron‐Rich Siloxide Ligands

et al. 2014

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The synthesis, structure, and reactivity of stable homoleptic heterometallic LnL 4 K 2 complexes of divalent lanthanide ions with electron-rich tris(tert-butoxy)siloxide ligands are reported. The [Ln(OSi(OtBu) 3 ) 4 K 2 ] complexes (Ln = Eu, Yb) are stable at room temperature, but they promote the reduction of azobenzene to yield the KPhNNPh radical anion as well as the reductive cleavage of CS 2 to yield CS 3 2À as the major product. The Eu III complex of the radical anion PhNNPh is structurally characterized. Moreover, [Yb(OSi(OtBu) 3 ) 4 K 2 ] can reduce CO 2 at room temperature. Release of the reduction products in D 2 O shows the quantitative formation of both oxalate and carbonate in a 1:2.2 ratio. The bulky siloxide ligands enforce the labile binding of the reduction products providing the opportunity to establish a closed synthetic cycle for the Yb II -mediated CO 2 reduction. These studies show that the presence of four electron-rich siloxide ligands renders their Eu II and Yb II complexes highly reactive.

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“…Specific reviews have also focused on activation by group 4 metals [40][41][42], iron [31,43,44], molybdenum [24,[45][46][47], and the mid-to-late transition metal centres [48]. In terms of rare earth N2 activation; an account of work from Evans and co-workers to 2004 has been reported [49], and Gardiner more recently reviewed the chemistry of the lanthanides with dinitrogen and reduced derivatives [50]. The area of actinide N2 activation has been discussed in the context of small molecule activation by trivalent uranium complexes [51,52].…”

Section: Open Accessmentioning

confidence: 99%