Half-Sandwich Lanthanide(III) Complexes Coordinated by Two α-Iminopyridine Radical Anions

Trifonov, Alexander A.; Gudilenkov, Ivan D.; Larionova, Joulia; Luna, Carlos; Fukin, Georgy K.; Cherkasov, Anton V.; Poddel’sky, Andrey I.; Druzhkov, N. O.

doi:10.1021/om9004143

Cited by 30 publications

(9 citation statements)

References 42 publications

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“…The palladium centre in complex 2 can be considered as palladium(0), and in good agreement it adopts a typical trigonal planar geometry expected for d 10 -ML 3 complexes. The above data suggest that coordination of palladium to [1] tigers an internal two-electron transfer from the starting complex [1] to the palladium(II) centre.…”

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confidence: 55%

“…[ 8 ] However, those incorporating the monoanionic * radical form (L • ) of the ligand are restricted to a few bis(ligand)-metal complexes of the first-row transition metal ions, [9] and lantanides, [10] and complexes with the closed-shell 2e reduced dianionic form of these ligands (L 2 ) are extremely rare. [9a, 11] We recently reported a unique method to prepare an anionic iridium(I) complex containing dianionic {bpa-2H} 2 ligand, [12] which is the 2e reduced form of the -iminopyridine ligand bpi (Scheme 1).…”

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confidence: 99%

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Developing Synthetic Approaches with Non‐Innocent Metalloligands: Easy Access to Ir^I/Pd⁰ and Ir^I/Pd⁰/Ir^I Cores

et al. 2011

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Schuldig der Anklage, so lautet das Urteil für den anionischen Iridium‐Komplex [Ir(bpa−2 H)(cod)]− in Reaktionen mit Palladium(II)‐Verbindungen. Der Transfer von zwei Elektronen vom Ir‐Komplex zu Pd ermöglicht die einfache Herstellung von zwei‐ und dreikernigen π‐Imin‐koordinierten Pd0‐Verbindungen wie [{Ir(PyCH2NCHPy)(cod)}2Pd] (siehe Bild; C weiß, Ir rot, N blau, Pd gelb). bpa−2 H: doppelt deprotoniertes N,N‐Bis(2‐picolyl)amin (bpa); cod: 1,5‐Cyclooctadien.

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confidence: 99%

Developing Synthetic Approaches with Non‐Innocent Metalloligands: Easy Access to Ir^I/Pd⁰ and Ir^I/Pd⁰/Ir^I Cores

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“…The current investigation focuses on iminopyridine chelates. Our choice of the iminopyridine ancillary ligand results from its redox-active nature that helps to stabilize low-oxidation-state metal precursors and to mediate electron transfer upon binding and reduction of substrates . Toward this goal, we have recently reported two dinucleating bis(iminopyridine) ligands, L 1 and L 2 (see Figure ) .…”

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Steric and Electronic Effects in the Formation and Carbon Disulfide Reactivity of Dinuclear Nickel Complexes Supported by Bis(iminopyridine) Ligands

et al. 2013

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We are developing bimetallic platforms for the cooperative activation of heteroallenes. Toward this goal, we designed a new family of bis(iminopyridine) ((N,N′-1,1′-(1,4-phenylene)bis(N-(pyridin-2-ylmethylene)methanamine) and N,N′-1,1′-(1,4-phenylene)bis(N-(1-(pyridin-2-yl)ethylidene)methanamine)) dinickel complexes, synthesized their CS2 compounds, and studied their reactivity. Bis(iminopyridine) ligands L react with Ni(COD)2 to form Ni2(L)2 complexes or Ni2(L)(COD)2 complexes as a function of the steric and electronic properties of the ligand precursor. Product structures disclosed an anti geometry in the Ni2(L)(COD)2 species and helical (anti) structures for Ni2(L)2 complexes. Carbon disulfide adducts Ni2(L)(CS2)2 were obtained in good yields upon addition of CS2 to Ni2(L)(COD)2 or in a one-pot reaction of L with 2 equiv of both Ni(COD)2 and CS2. Ni2(L)(CS2)2 complexes are highly flexible, displaying both syn and anti conformations (shortest S- - -S separations of 5.0 and 9.5 Å, respectively) in the solid state. DFT calculations demonstrate virtually no energy difference between the two conformations. Electrochemical studies of the Ni2(L)(CS2)2 complexes displayed two ligand-based reductions and a broad CS2-based oxidation. Chemical oxidation with [FeCp2]+ liberated free CS2. The addition of NHC (NHC = 1,3-di-tert-butylimidazolin-2-ylidene) to Ni2(L)(CS2)2 yielded Ni2(NHC)2(CS2)2, in which both carbon disulfide ligands are bridging two Ni centers.

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“…The a-iminopyridine N-2,6-diisopropylphenylimino-2-pyridine (IPy) has also been introduced in lanthanide chemistry. [33,34] In this context, a potassium derivative of the monoanionic form of a-iminopyridine was prepared in situ, but not further characterized.[34] The doubly reduced dianion has only been observed in two magnesium complexes so far. [35] In contrast, the reaction of "GaI" with a-iminopyridine leads to reductive coupling of the coordinated ligand to give neutral diamido-digallium complexes.…”

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Sodium and Potassium Salts of Mono‐ and Dianionic α‐Iminopyridines

Nayek

Arleth

Trapp

et al. 2011

Chemistry A European J

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[a] a-Diimine (1,4-diaza-1,3-butadiene) ligands are well established in main-group, transition-metal, and lanthanide chemistry. [1][2][3][4][5][6][7] Beside their application as ligands for latetransition-metal complexes, which can function as active and selective catalysts for a-olefin polymerization, [8] a-diimine and related ligands are of special interest due to their ability to undergo redox chemistry.[9] They have frequently been described as "non-innocent" ligands. [10][11][12] For example, in lanthanide chemistry, it has been found that the formal oxidation state of Eu [13] and Yb [14] depends on the nature of the substituents on the a-diimine ligand and on the ligand on the metal center. Thus, in both cases, the a-diimine acts either as neutral ligand or as radical anion. Reduction of adiimines, using either alkali metals or electrochemical methods, leads in each case to the corresponding radical anions [15][16][17][18] and eventually to diamagnetic dianions, [17][18][19][20][21][22][23][24] albeit at much more negative potentials. In contrast to the well-established chemistry of a-diimines, the related a-iminopyridines are much less investigated. The three different redox states of a-iminopyridines are shown in Scheme 1. The neutral system L 0 has been extensively used as ligand for late transition metals. [4,[25][26][27][28][29] Only recently, the monoanion LC À and the doubly reduced dianion L 2À were investigated as ligands in more detail. Recent reports showed a series of bis(a-iminopyridine)-metal complexes featuring aluminum [30] and the first-row transition ions (Cr, Mn, Fe, Co, Ni, and Zn) [31,32] with the monoanionic, and thus paramagnetic p-radical form of the ligand in coordination complexes. The a-iminopyridine N-2,6-diisopropylphenylimino-2-pyridine (IPy) has also been introduced in lanthanide chemistry. [33,34] In this context, a potassium derivative of the monoanionic form of a-iminopyridine was prepared in situ, but not further characterized.[34] The doubly reduced dianion has only been observed in two magnesium complexes so far. [35] In contrast, the reaction of "GaI" with a-iminopyridine leads to reductive coupling of the coordinated ligand to give neutral diamido-digallium complexes. [36] Based on this information, we were interested in a comprehensive study of the properties of the alkali metal salts of the monoanionic p-radical and the doubly reduced dianion of a-iminopyridine in solution and in the solid state. We report here the synthesis, characterization and magnetic properties of sodium and potassium salts of the mono-and dianionic a-iminopyridines.N-2,6-Diisopropylphenylimino-2-pyridine (IPy) was prepared according to literature procedures.[37] As a first entry point, we examined the electrochemical properties of IPy using cyclic voltammetry at room temperature in THF. As can be seen from Figure 1, we detected a quasi-reversible one-electron reduction process centered at E 0 1=2 = À2.57 V (vs. the ferrocene/ferrocenium couple, Fc/Fc + ), with a peakto-peak separation of 15...

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Half-Sandwich Lanthanide(III) Complexes Coordinated by Two α-Iminopyridine Radical Anions

Cited by 30 publications

References 42 publications

Developing Synthetic Approaches with Non‐Innocent Metalloligands: Easy Access to Ir^I/Pd⁰ and Ir^I/Pd⁰/Ir^I Cores

Developing Synthetic Approaches with Non‐Innocent Metalloligands: Easy Access to Ir^I/Pd⁰ and Ir^I/Pd⁰/Ir^I Cores

Steric and Electronic Effects in the Formation and Carbon Disulfide Reactivity of Dinuclear Nickel Complexes Supported by Bis(iminopyridine) Ligands

Sodium and Potassium Salts of Mono‐ and Dianionic α‐Iminopyridines

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Half-Sandwich Lanthanide(III) Complexes Coordinated by Two α-Iminopyridine Radical Anions

Cited by 30 publications

References 42 publications

Developing Synthetic Approaches with Non‐Innocent Metalloligands: Easy Access to IrI/Pd0 and IrI/Pd0/IrI Cores

Developing Synthetic Approaches with Non‐Innocent Metalloligands: Easy Access to IrI/Pd0 and IrI/Pd0/IrI Cores

Steric and Electronic Effects in the Formation and Carbon Disulfide Reactivity of Dinuclear Nickel Complexes Supported by Bis(iminopyridine) Ligands

Sodium and Potassium Salts of Mono‐ and Dianionic α‐Iminopyridines

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Product

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Developing Synthetic Approaches with Non‐Innocent Metalloligands: Easy Access to Ir^I/Pd⁰ and Ir^I/Pd⁰/Ir^I Cores

Developing Synthetic Approaches with Non‐Innocent Metalloligands: Easy Access to Ir^I/Pd⁰ and Ir^I/Pd⁰/Ir^I Cores