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New near-IR electroluminescent complexes of Pr3+, Nd3+, Ho3+, Er3+, Tm3+, Yb3+with N,O-chelated ligands, Ln2(OON)6(OON = 2-(2-benzoxyazol-2-yl)phenolate) and Ln2(SON)6(SON = 2-(2-benzothiazol-2-yl)phenolate), were synthesized by the reaction of Ln[N(SiMe3)2]3and the corresponding N,O-chelating ligand. X-Ray analysis for the Pr and Nd compounds reveals centrosymmetric dimeric structures of the complexes. The solid-state electronic absorption spectra and the electroluminescent spectra show long-wavelength 4f–4f transitions which provide potential use of the compounds as NIR emitting materials in organic light-emitting devices (OLEDs). When constructing OLEDs based on Ln2(OON)6and Ln2(SON)6, the best results were achieved with the Nd3+and Yb3+complexes, where the NIR wall plug efficiency of the ITO/TPD/Ln-complex/BATH/Yb system is 0.82 and 1.22 mW W−1, respectively. [ABSTRACT FROM AUTHOR]

A steric control on the reductive capacity of ytterbocenes towards iminopyridine ligands is described. The reaction of (η5-C9H7)2Yb(THF)2with a series of 6-organyl-2-(aldimino)pyridyl ligands (IPy) takes place with the replacement of two THF molecules by one IPy unit. In contrast to the rich reductive ytterbocene chemistry described in the presence of the unsubstituted (aldimino)pyridyl ligand, all 6-aryl substituted IPys scrutinized hereafter are involved into the metal coordination as neutral bidentate {N,N} or tridentate {N,N,S; N,N,O} ligands, with no changes of the metal oxidation state in the final complexes. A series of YbIImetallocene complexes of general formula (η5-C9H7)2YbII(η2or η3)[2,6-iPr2(C6H3)NCH(C5H3N)-6-R)] have been isolated and completely characterized. The stereo-electronic role of the aryl substituents in the IPy ligands on the ytterbocene redox chemistry has also been addressed. [ABSTRACT FROM AUTHOR]

The first monomeric anhydrous scandium tris(8-quinolinolate) complex 1with the 2-amino-8-quinolinolate ligands and the Sc2Q6dinuclear complex 2with the unsubstituted 8-quinolinolate ligands have been synthesized and characterized by X-ray analysis and DFT calculations. The intramolecular hydrogen bonds appear to be responsible for the unique monomeric structure of complex 1. The DFT-based analysis of the electron density topology reveals the (3,−1) critical points corresponding to the OH and NH bonds. The two scandium atoms in compound 2are inequivalent due to different ligand surroundings. They are coordinated by seven (5O, 2N) and eight (4O, 4N) ligand atoms. The increase in the coordination number is accompanied by a decrease in the positive charge of the metal atom as evidenced by the DFT calculations. [ABSTRACT FROM AUTHOR]

New heterobimetallic borohydrido neodymium complexes {[OONN]1Nd(BH4)(μ-BH4)Li(THF)}2(1) and [OONN]3Nd(BH4)(μ-BH4)Li(THF)2(3) supported by diamino-bis(phenoxide) ligands ([OONN]1= {CH2N(Me)CH2-3,5-Me,t-Bu-C6H2O}2; [OONN]3= C5H4NCH2N{CH2-3,5-Me,t-Bu-C6H2O}2) were synthesized by the reactions of Nd(BH4)3(THF)2with equimolar amounts of dilithium derivatives of diamino-bis(phenol)s Li2[OONN]nand isolated in high yields. In the case of Li2[OONN]2([OONN]2= Me2NCH2CH2N{CH2-3,5-t-Bu-C6H2O}2), the same synthetic procedure afforded the heterobimetallic bis(phenoxide) complex Li{Nd[OONN2]2} (2). The structures of complexes 1–3were established by X-ray diffraction studies. Compounds 1–3act as single-site initiators for the ring-opening polymerization (ROP) of racemic lactide and racemic β-butyrolactone under mild conditions (20 °C), providing atactic polymers with controlled molecular weights and relatively narrow polydispersities (Mw/Mn= 1.07–1.82). While 1and 3initiate polymerization viatheir borohydride groups, ROP with 2proceeds viainsertion into the Nd–O(ligand) bond. [ABSTRACT FROM AUTHOR]

The reaction of (dpp-BIAN)Mg(THF)3(1) with anhydrous CrCl3in THF at 80 °C affords the mixed chromium–magnesium complex (dpp-BIAN)Cr(μ-Cl)3Mg(THF)3(2). The treatment of 2with 1,4-dioxane causes the elimination of MgCl2and the formation of dimeric [(dpp-BIAN)Cr(μ-Cl)(THF)]2(3). The reaction of (dpp-BIAN)Na2with CrCl3gives the chlorine-free compound [Na(THF)6][(dpp-BIAN)2Cr] (4). Paramagnetic complexes 2, 3and 4have been characterized by IR and electronic absorption spectroscopy. The magnetic susceptibilities of 2and 4have been determined in solution using Evans’ method. The molecular structures of 2–4have been established by single crystal X-ray analysis. [ABSTRACT FROM AUTHOR]

Reaction of two equivalents of n-BuLi with sterically demanding amine-bis(phenol) compounds, H2O2NN′R (Me2NCH2CH2N{CH2-3,5-R2-C6H2OH}2; R = t-Bu or t-Pe (tert-pentyl)) yields isolable lithium complexes, Li2(O2NN′R), in good yields. Upon reaction with one equivalent of LnCl3(THF)x, the lithium salts afford rare earth amine-phenolate chloride complexes in good yields, Ln(O2NN′R)Cl(THF); Ln = Y, Yb, Ho, Gd, Sm, Pr. Crystals of Y(O2NN′t-Bu)Cl(THF), 1, and Sm(O2NN′t-Bu)Cl(DME), 2, suitable for single crystal X-ray crystallographic analysis were obtained. In contrast to previously reported [{Gd(O2NN′t-Pe)(THF)(μ-Cl)}2] and related La and Sm complexes, these species are monomeric. 1 contains Y in a distorted octahedral environment bonded to two amine, two phenolate, one THF and one chloride donor. 2 contains Sm in a distorted capped trigonal prismatic environment bonded to two amine, two phenolate, two DME oxygens and one chloride donor. The Ln(O2NN′t-Pe)Cl(THF) complexes were active initators for the controlled ring-opening polymerization of ε-caprolactone with a tendency to form low molecular weight cyclic polyesters (Mn 3000–5000). The conversion rates, although slower than related amido and alkyl species, were different for monomeric and dimeric initiators. The size of the metal centre also affected the conversions and the molecular weights achieved. [ABSTRACT FROM AUTHOR]