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The reactions of monomeric [(dpp-Bian)M(thf)4] (M = Ca (1a), Sr (1b); dpp-Bian = 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene) with 4,4'-bipyridyl (4,4'-bipy) proceed with electron transfer from dpp-Bian2- to 4,4'-bipy0 to afford calcium and strontium complexes containing simultaneously radical-anionic dpp-Bian- and 4,4'-bipy- ligands. In tetrahydrofuran (thf) the reactions result in 1D coordination polymers [{(dpp-Bian)M(4,4'-bipy)(thf)2}·4thf]n (M = Ca (2a), Sr (2b)), while in a thf/benzene mixture the reaction between 1a and 4,4'-bipy affords the 2D metal-organic framework [{(dpp-Bian)Ca(4,4'-bipy)2}·2thf·2C6H6]n (3). The structures of compounds 2a,b and 3 have been determined by single-crystal X-ray analyses. The presence of the ligand-localized unpaired electrons allows the use of ESR spectroscopy for characterization of the compounds 2a,b and 3. DFT calculations of model calcium complexes with the dpp-Bian, 4,4'-bipy, and thf ligands confirm the energetically favorable open-shell configurations of the molecules bearing the 4,4'-bipy fragments. The magnetic susceptibility measurements confirm the presence of two unpaired electrons per monomeric unit in 2a,b and 3. The thermal stability of compounds 2a,b and 3 was studied by thermogravimetric analysis (TGA). To the best of our knowledge, 3 is the first MOF simultaneously containing two different paramagnetic bridging ligands inside the framework.

Treatment of 3a,6a-diaza-1,4-diphosphapentalene (DDP) with an excess of PhBCl2 yields the corresponding bis(borane) adduct DDP(PhBCl2)2 (14), demonstrating the availability of two lone pairs on the phosphorus center. The reaction between DDP and B(C6F5)3 yields (1 : 1) phosphino-borane complex 16. The free lone electron pair on the pyramidal P atom in 16 participates in the intramolecular non-covalent interactions P(1)⋯F(1) and P(1)⋯F(6) giving additional 3.9 and 2.8 kcal mol−1, respectively, for stabilization of the complex. This through-space interaction appears in the 31P NMR spectrum as large spin–spin coupling constants of 271 and 219 Hz. The addition of water to 16 (1 : 1) leads to the formation of the insertion product 17 having –H2P–O–B(C6F5)3 moiety. The reaction of DDP with BH3·SMe2 proceeds in several stages, which include the insertion of the masked phosphinidene into the B–H and P–H bonds of the intermediate compounds followed by the dehydrocoupling step and formation of diphosphine 18. The last compound exists in solution as a set of stereoisomers.

In the search for new f–d luminescent complexes of Eu(II) and Yb(II) the metathesis reactions of diiodides of these metals with perfluorinated 2-mercaptobenzothiazolates of alkali metals were studi...

By crystallization of sterically hindered 1,2-bis[(2,6-dibenzhydryl-4-methylphenyl)imino]acenaphthene (dbhmp-bian) (1) from tetrahydrofuran (THF) or acetone two crystalline forms of (dbhmp-bian)(THF)3(1a) and dbhmp-bian (1b) are isolated and structurally characterized. In DFT calculations (B3LYP/6-31G(d) level), no significant differences between the electronic structures of 1 and some other Ar-bian ligands (Ar = 2,6-Me2-C6H3; 2,6-Et2-C6H3; 2,6-iPr2-C6H3) are revealed. HOMO and LUMO energies of these compounds are in the ranges −5.60 eV … −5.51 eV and −2.07 eV … −2.04 eV respectively. The geometric parameters of the diimine moiety of the ligands obtained from DFT calculations and XRD data are almost identical.

The reaction of dialane (dpp-Bian)Al–Al(dpp-Bian) (1) (dpp-Bian is dianion of 1,2-bis[(2,6-diisopropylphenyl)imino]-acenaphthene) with 1 mol equiv of 1,3-diisopropyl-4,5-dimethylimidazol-2-ylidene ...

Three-nuclear clusters Nd2LnI5(S2)(S2N2)(THF)9 (Ln = Tb, Tm) were prepared by the disproportionation reaction of iodide-nitride [(NdI)3N2](THF)6 with LnI3(THF)3 in the presence of sulfur. Molecule of the cluster contains a flat inorganic core formed by two Nd and Ln atoms connected by dithiadiazine group. One of the Nd atoms is bound to the Ln3+ ion, besides terminal N atom of the bridge S2N2 fragment, by a bridge fragment S2. The second Nd atom is coordinated by two iodine anions and SN group forming unusual NdSN tree-member cycle. Structure of inorganic framework of the complexes is similar to that of earlier obtained monometallic analogues Ln3I5(S2)(S2N2)(THF)10 (Ln = Nd, Dy). In both new clusters the Ln atoms have the same coordination surrounding consisting of one iodine anion, S2 group and N atom of dithiadiazine ligand and occupy in the framework Nd2Ln(S2)(S2N2) the same position which corresponds to the lowest energy of the molecule. The nitride [(NdI)3N2](THF)6 in the presence of sulfur easy reacts as well with triiodides of La and Sm. Products isolated in these reactions do not form crystals suitable for X-ray study but the data of elemental analysis, fragment analysis, the found Nd: Ln ratio, spectroscopic and magnetic measurements allow to conclude that the structure of La, Sm products is similar to that of the above Tb, Tm analogs.

A tris-dioxolene manganese complex was synthesized and characterized (dioxolene- mono- and dianions of 3,6-DBQ-pipe, which is 3,6-di-tert-butyl-o-benzoquinone having a N,N’-piperazine bicycle as substituent in 4,5-positions). According to the bonds lengths distribution in the chelate cycles of the ligands the complex was identified as a bis-o-semiquinone-catecholato derivative of Mn(IV). Variable temperature magnetic susceptibility measurements indicate one unpaired electron per complex molecule as a result of strong intramolecular antiferromagnetic exchange interactions. The bis-o-semiquinone-catecholato manganese complex interacts with pyridine substituted by a nitronyl-nitroxide moiety forming a six-coordinate compound. The X-ray structural diffraction study of the complex executed at 100 K indicates a trans-arrangement of the pyridine ligands and the two catecholato dianionic chelates. Variable temperature magnetic susceptibility measurements of the complex with nitronyl-nitroxide give a magnetic moment of 5.5 µB which cannot be achieved in the spin system S = 3/2 (Mn4+) and 2 × S = 1/2 (two nitronyl-nitroxides). A valence tautomeric interconversion is proposed when the high multiplicity states [Mn3+(catecholate)(semiquinone)] and [Mn2+(semiquinone)2] are partly populated.

Herein, we present the synthesis, single-crystal X-ray structures, and spectroscopic properties for the 1:1 donor-acceptor complexes of 1,2,4,5-tetracyanobenzene (TCNB) with annelated 3a,6a-diaza-1,4-diphosphapentalenes (DDPs) based on cyclohexanone azine (

In the search for a way to organic up-converter materials the complex [(OON)2Er(THF)](μ-O)[(OON)2Yb(THF)] with the (benzoxazol-2-yl)phenolate (OON) ligand was synthesized. Upon excitation by laser with λex 405 nm light the complex displayed only emission of the Yb3+ ion indicating the lack of energy transfer from Yb to Er. To develop a method for preparation of other up-converter materials the complexes [Yb4(SON)8(μ4-O)(OH)2 and [Eu4(OON)10Li2(3-O)2] with (benzothiazol-2-yl)phenolate (SON) and (benzoxazol-2-yl)phenolate ligands were synthesized using water as a co-reagent. The X-ray study revealed that the clusters contain μ2-O, μ3-O and μ4-O bridges and short Ln…Ln contacts. These modelling syntheses showed that the method is applicable for preparation of potential up-convertion materials with Ln-O-Ln’ groupings.

New triphenylantimony(V) catecholates 1-3 based on 3-formyl-substituted catechols L1-L3 have been synthesized and characterized (L1 is 2,3-dihydroxy-4,6-di-tert-butyl-benzaldehyde, L2 is 2,3-dihydroxy-5,5,8,8-tetramethyl-5,6,7,8-tetrahydronaphthalene-1-carbaldehyde, and L3 is 2,3-dihydroxy-4,5,5,8,8-pentamethyl-5,6,7,8-tetrahydronaphthalene-1-carbaldehyde). The crystal structures of complexes 1, 2 have been determined by single-crystal X-ray analysis. It was found that the coordination sphere of the antimony atom is supplemented to 6 due to the intermolecular donor-acceptor bond of Sb…O with the formyl oxygen of the neighboring catecholate molecule. As a result, the formation of 1D-polymer structures for 1, 2 is observed.

In search of new fully fluorinated ligands which effectively sensitized the lanthanide luminescence the 4,5,6,7-tetrafluoro-1,3-benzothiazol-2(3Н)-thione (HmbtF) was proposed. Based on this ligand a set of new complexes LnL3(THF)2 (Ln1) (Ln = Nd, Gd, Tb, Dy, Er, Yb) was synthesized and their luminescence were studied. The structure of the compounds was established with an example of Gd derivative. The triplet state energy of mbtF was found to be 21500 cm−1 that enables the resonant energy transfer to Dy3+, Tb3+, Nd3+ and Er3+ ions and stipulates metal-centered emission of some complexes. In case of Yb1 the observed luminescence of Yb3+ ion probably occurs due to the non-resonant energy transfer.

A number of new zinc complexes with 1,3-di‑tert‑butyl‑7-methylacridin-4-olate or 1,3-di‑tert‑butyl‑7-bromoacridin-4-olate ligands Zn(AcrMe)2, Zn(AcrMe)2(DMSO), Zn(AcrMe)2(Py)2, [Zn(Et)(AcrMe)]2, Zn(AcrBr)2, Zn(AcrBr)2(DMSO) and [Zn(Et)(AcrBr)]2 were synthesized by the reaction of respective acridinol with Et2Zn and structurally characterized. All compounds exhibited photoluminescence in the form of a single band in the 600 - 700 nm region. Compounds Zn(AcrMe)2 and [Zn(Et)(AcrMe)]2 displayed also weak electroluminescent properties. It is found that introduction of both alkyl or bromine substituents into acridine rings cause the hypsochromic shift of emission band. The resistance of organozinc complexes to strong ionizing radiation was studied using the example of [Zn(Et)(AcrMe)]2. X-ray diffraction study showed that the molecular structure of the complex did not change after strong neutron-gamma irradiation for 45 h.

Herein, complexes [ZnL]2 (1), {(H2O)Zn(μ-L)Yb[OCH(CF3)2]3} (2), {[(CF3)2HCO]Zn(μ-L)Yb[OCH(CF3)2](μ-OH)}2 (3), and [(H2O)Ln2(L)3] (Ln = Yb (4) and Gd (5)) containing a bridging Schiff-base ligand (H2L = N,N'-bis(3-methoxy salicylidene)phenylene-1,2-diamine) were synthesized. The compounds 1-4 were structurally characterized. The ytterbium derivatives 2-4 exhibited bright NIR metal-centred photoluminescence (PL) of Yb3+ ion under one- (λex = 380 nm) and two-photon (λex = 750 nm) excitation. The superior luminescence properties of complex 2, which was suggested as a marker for NIR bioimaging, were explained via the strong absorption of the 375 nm LMCT state of the ZnL chromophore, efficient energy transfer from ZnL towards Yb3+ through a reversible ligand-to-lanthanide electron transfer process, and absence of luminescence quenchers (C-H and O-H groups) in the first coordination sphere of the rare-earth atom.

The compound K2Th2(NO3)10·15H2O was synthesized, and its crystal structure was determined by X-ray diffraction analysis: space group P 1 ¯ ; a = 10.3068(9), b = 13.1642(11), c = 13.9605(12) A, α = 95.276(2)°, β = 90.425(2), γ = 92.749(2)°, Z = 2; R = 0.0379. Thermal conditions of decomposition of the compound are studied by differential scanning calorimetry and high-temperature X-ray powder. The compound was studied by IR spectroscopy and was assigned bands.

To obtain new efficient lanthanide-based NIR luminophores perfluorinated 2-mercaptobenzothiazole was used as a ligand. The ate-complexes [(Ln(mbtF)4)-(Na(DME)3)+] of Nd (1), Sm (2), Tb (3), Er (4), Yb (5) and [(Y(mbtF)4)-(Li(DME)3)+] (6) were synthesized in high yields by the reactions of the respective silylamide compounds Ln[N(SiMe3)2]3 and M[N(SiMe3)2] (M = Li, Na) with 4,5,6,7-tetrafluoro-1,3-benzothiazol-2(3H)-thione (HmbtF) in DME media. The complexes 1-3 and 6 were structurally characterized by X-ray diffraction analysis. It has been shown that the mbtF ligands sensitize the luminescence of Nd, Sm, Tb, Er and Yb ions upon mild UV or blue light excitation. The NIR luminescence of crystalline compounds 1, 2, 4 and 6 has been studied by time-resolved techniques. As expected, the compounds exhibit prolonged NIR luminescence due to the removal of C-H groups from lanthanide centers and the absence of C-O bonds in the coordination sphere of the lanthanides. The synthesized compounds are promising materials for NIR laser applications.

Alkoxides [Ln(OR)3(DME)]2 (R = CH(CF3)2, Ln = Sm (1), Yb (2)), [Ce(OR)3(Phen)]2 (3) (Phen = 1,10-phenanthroline), [Ce(OR′)3(DME)2]2 (R′ = C(CF3)3) (4), {Gd(OR′)3(DME)2} (5), {Ln2[O(CF3)2C–C(CF3)2O]3} (Ln = Ce (6), Gd (7)), {Ce2[O(CF3)2C–C(CF3)2O]3(Phen)2} (8), and {Ce[O(CF3)2C–C(CF3)2O][O(CF3)2–C(CF3)2OH](Phen)2} (9) were synthesized by the reactions of silylamides Ln[N(SiMe3)2]3 with respective fluorinated alcohols. The heterovalent trinuclear complex {Sm2(μ2-OR)3(μ3-OR)2Sm(OR)2(THF)2.5(Et2O)0.5} (10) was obtained by treatment of SmI2(THF)2 with ROK. The reaction of europium(II) and yttrium(III) silylamides with ROH afforded the heterobimetallic alkoxide {Eu2(μ2-OR)3(μ3-OR)2Y(OR)2(DME)2} (11) containing divalent europium. The molecular structures of 1, 2, 3, 9, 10 and 11 were determined by X-ray analysis. All the prepared cerium derivatives as well as the europium–yttrium isopropoxide upon UV excitation exhibited photoluminescence in the regions of 370–425 (for Ce3+) and 485 nm (for Eu2+) which was assigned to 4d→5f transitions.

A set of Y, Nd, Tm and Yb complexes containing, along with 3-(2-benzothiazol-2-yl)-2-naphtholate (L), the 8-oxyquinolate (Q), pentafluorophenolate, cyclopentadienyl (Cp) or methylcyclopentadienyl (CpMe) ligands were synthesized using Ln[N(SiMe3)2]3, Ln(Cp)3 or Ln(CpMe)3 as starting materials. Depending on molar ratio of initial reagents the mononuclear, dinuclear or tetranuclear products were isolated from the reaction mixtures. The complexes Y2(L)4(CpMe)2, Nd2(L)4(Cp)2, Yb(L)(Cp)2, Y2(L)3(Q)2(CpMe) and Y4(L)(Q)11 were structurally characterized. The synthesis routes and conditions governing the set of ligands in products and their nuclearity are discussed.

Iminopyridine modified by TEMPO nitroxide was utilized for the synthesis of an octahedral bis(o-semiquinonato)cobalt complex. Variable-temperature magnetic susceptibility measurements detect a valence tautomeric transformation in the temperature range 200-300 K. A reproducible hysteresis loop of about 40 K width is observed on the magnetic moment temperature dependence in the transition region. Differential scanning calorimetry measurements confirm different temperatures of phase transitions accompanying a valence-tautomeric transformation upon heating and cooling. Attempts to study the structural changes associated with the valence-tautomeric transformation by single-crystal X-ray diffraction failed because of the crystal destruction taking place upon cooling from 220 K. The powder X-ray diffraction pattern indicated an essential change of the unit cell upon cooling from 240 K.

To obtain luminescent lanthanide complexes with a low energy LMCT state the 2-(2'-mercaptophenyl)benzothiazolates, Ln(SSN)3, and 2-(2'-mercaptophenyl)benzoxazolates, Ln2(OSN)6 (Ln = Gd, Yb), were synthesized by the reaction of amides Ln[N(SiMe3)2]3 with respective thiophenols. Ytterbium complexes were structurally characterized by X-ray diffraction analysis. Cyclic voltammetry revealed that the deprotonated mercaptophenyl ligands have significantly lower oxidation potentials than their phenoxy analogues and some β-diketones. The photophysical properties of Gd and Yb compounds were studied both in solution and in the solid state. The fluorescence spectra of the compounds in solution display the bands of the keto and enol forms of the ligands. No energy transfer from the organic part to Yb3+ has been detected in solutions of both Yb complexes, whereas in solids an intense metal-centered emission in the near infrared region was observed. The solid Gd compounds exhibited room temperature phosphorescence caused by unusually efficient intersystem crossing facilitated by the essentially reducing properties of OSN and SSN ligands. To explain the sensitization process occurring in solids Yb2(OSN)6 and Yb(SSN)3 a specific non-resonant energy transfer mechanism via a ligand to metal charge transfer state has been proposed. Based on the Yb derivatives, NIR-emitting OLEDs with 860 μW cm-2 maximal irradiance were obtained. Their Gd counterparts showed bright electrophosphorescence (up to 1350 cd m-2) in the devices containing doped emission layers.