Search

Monomeric and dimeric NHP complexes were prepared by reaction of N-heterocyclic diphospholene with Fe, Co and Ni carbonyls.

The new ligand 8,10-di-tert-butylbenzo[b][1,10]phenanthrolin-11-ol and its lanthanide complexes were obtained and their photoluminescence and electrochemical properties were studied.

Today we see an increasing demand for new fluorescent materials exhibiting various sensory abilities due to their broad applicability ranging from the construction of flexible devices to bioimaging. In this paper, we report on the new fluorescent pigments AntTCNE, PyrTCNE, and PerTCNE which consist of 3–5 fused aromatic rings substituted with tricyanoethylene fragments forming D-π-A diad. Our studies reveal that all three compounds exhibit pronounced rigidochromic properties, i.e., strong sensitivity of their fluorescence to the viscosity of the local environment. We also demonstrate that our new pigments belong to a very rare type of organic fluorophores which do not obey the well-known empirical Kasha’rule stating that photoluminescence transition always occurs from the lowest excited state of an emitting molecule. This rare spectral feature of our pigments is accompanied by an even rarer capability of spectrally and temporally well-resolved anti-Kasha dual emission (DE) from both higher and lowest electronic states in non-polar solvents. We show that among three new pigments, PerTCNE has significant potential as the medium-bandgap non-fullerene electron acceptor. Such materials are now highly demanded for indoor low-power electronics and portable devices for the Internet-of-Things. Additionally, we demonstrate that PyrTCNE has been successfully used as a structural unit in template assembling of the new cyanoarylporphyrazine framework with 4 D-π-A dyads framing this macrocycle (Pyr4CN4Pz). Similarly to its structural unit, Pyr4CN4Pz is also the anti-Kasha fluorophore, exhibiting intensive DE in viscous non-polar medium and polymer films, which strongly depends on the polarity of the local environment. Moreover, our studies showed high photodynamic activity of this new tetrapyrrole macrocycle which is combined with its unique sensory capacities (strong sensitivity of its fluorescent properties to the local environmental stimuli such as viscosity and polarity. Thus, Pyr4CN4Pz can be considered the first unique photosensitizer that potentially enables the real-time combination of photodynamic therapy and double-sensory approaches which is very important for modern biomedicine.

The heteroligand complexes CpLn(BQ)2(DME) (BQ = 10-oxybenzo[h]quinoline, Cp = cyclopentadienyl, Ln = La (1), Nd (2), Sm (3), Gd (4)) were synthesised by the reaction of Cp3Ln with (BQ)H. The complexes of La, Nd and Sm were structurally characterised. In the case of ytterbium the reaction affords Cp2Yb(BQ)(DME) (5) and homoligand binuclear complex Yb2(BQ)6 (6) iregardless of the molar ratio of initial reagents. Upon UV excitation all the complexes gave rise to fluorescence of ligands in the visible region. The photoluminescent spectrum of compound 1 also contains a phosphorescent band with a lifetime longer than 10 ms. The complexes of Nd, Sm and Yb along with ligand emission display metal-centered luminescent f–f transitions.

A set of novel ditopic 2-mercaptothiazoles has been synthesized. Depending on the nature of the bisthiazoles their sodium salts can form coordination compounds or 2D polymers.

A series of bis(tetramethylaluminate) lanthanide complexes {2-[Ph2P═X]C6H4NC(tBu)N(2,6-Me2C6H3)}Ln(AlMe4)2 (X = O, Ln = La (1); X = O, Ln = Nd (2); X = O, Ln = Sm (3); X = S, Ln = La (4); X = S, Ln...

The isolable bis(tetramethylaluminate) lanthanide complexes [2-R2,6-XC6H4NC(tBu)(2,6-R12C6H3)]Ln(AlMe4)2 (R1 = R2 = X = Me, Ln = La (1); R1 = R2 = X = Me, Ln = Nd (2); R1 = iPr, R2 = H, X = OMe, Ln...

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.

The outcome of salt metathesis reactions between the equimolar amounts of LnCl3 and dimeric potassium diphenylmethanide {[2,2′-(4-MeC6H3NMe2)2CH]K(THF)}2 depends on the rare-earth metal ion. In the case of ScIII and YIII, the reactions afford chlorido-bis(diphenylmethanido) complexes {[2,2′-(4-MeC6H3NMe2)2CH]2LnIII(μ-Cl)}2, in which the diphenylmethanido ligands perform bidentate κ2-CN coordination according to the X-ray data. For YbIII and SmIII, these reactions result in the spontaneous reduction of LnIII to LnII and the formation of known bis(diphenylmethanido) complexes [2,2′-(4-MeC6H3NMe2)2CH]2LnII and the product of oxidative coupling of diphenylmethanido anions.

The interaction of 1,4-dichloro-3a,6a-diaza-1,4-diphosphapentalenes with metallic Na or Li or the naphthalene-Na anion-radical salt in THF proceeds through several successive stages: dehalogenation, two types of rearrangement of the heteropentalene fragment to form 1,6-diaza-3a,6a-diphosphapentalene- and 1,4-diaza-3a,6a-diphosphapentalene derivatives, and subsequent cleavage of the heteropentalene framework to give a stable aromatic 1,2,3-azadiphospholide ion.

N-Heterocyclic carbene is a versatile ligand for the preparation of copper( i ) and silver( i ) derivatives bearing the radical anion forms of redox active o-benzoquinone and o-iminobenzoquinone. The paramagnetic three-coordinated copper( i ) and silver( i ) o-benzosemiquinone and o-iminobenzosemiquinone complexes were prepared and characterized by EPR spectroscopy and X-ray diffraction analysis.

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...

Sm, Er, and Yb complexes containing anionic (4,5,6,7-tetrafluorobenzothiazol-2-yl)-2-(3,4,5,6-tetrafluoro)phenolate (SONF) and 3-(2-benzothiazol-2-yl)-2-naphtholate (NpSON) and neutral 1,10-phenathroline or 2,2'-bipyridine ligands were synthesized. The structures of complexes Yb(SONF)2-(NpSON)(DME)1.5 (II) and previously synthesized Er(SONF)3(DME) (I) were determined by X-ray diffraction (CIF files CCDC nos. 1972769 and 1972770, respectively). Upon excitation by light at λ 405 nm, all complexes showed luminescence of the ligands and Ln3+ ions. The OLED devices based on samarium complexes showed moderate intensi metal-centered emission of moderate intensity at a 19 V voltage.

The exchange reactions of equimolar amounts of potassium penta(benzyl)cyclopentadienide CpBn5K (CpBn5 = C5(CH2Ph)5) and SmI2(THF)2 or YCl3 afforded the corresponding half-sandwich derivatives [CpBn5Sm(DME)(μ-I)]2 (1) and [CpBn5YCl2(THF)]2[KCl(THF)2] (2). According to the X-ray diffraction data, the metal ions in complexes 1 and 2 are coordinated by CpBn5 ligands in a η5-fashion. The difference is that there is a short contact between the SmII cation and one benzyl group of the cyclopentadienyl ligand in structure 1, whereas such interaction is absent in structure 2.

2,5-Dihydroxy-3,6-di-tert-butyl-p-benzoquinone (QtBuDiol) reacts with Ph3SbBr2 in toluene in the presence of triethylamine to yield the ionic complex [Et3NH]+[(DionetBuDiolate)SbPh3Br]– (I). The same reaction in methanol leads to complete displacement of bromide ions from the antimony coordination sphere and gives triphenylantimony(V) 1,2-diolate (DionetBuDiolate)SbPh3 · MeOH (II · MeOH). The molecular structure of the complexes was determined by X-ray diffraction (CIF files CCDC no. 1960681 (I · toluene) and 1960682 (II · 2MeOH)). Both complexes are characterized by quinoid bond distribution in the six-membered carbon rings and by C=O double bonds in the Ph3SbO2C6(t-Bu)2O2 moieties. Formally, the complexes can be considered as 3,6-di-tert-butyl-o-benzoquinone derivatives with the organometallic Ph3SbO2 group in positions 4 and 5 of the quinone ring. The electrochemical reduction of II · MeOH in dichloromethane occurs at E1/2 = –1.52 V, which is significantly shifted to the cathodic region relative to the data for 3,6-di-tert-butyl-o-benzoquinone (E1/2 = –0.51 V). This redox potential shift indicates a significant decrease in the electron-withdrawing properties of the o-quinoid moiety, which is caused by the effect of the electron-donating catecholate metallacycle.

In this article, we report on the results of experimental and theoretical (DFT calculation of an isolated molecule) investigation of electron density in a triphenylantimony disorbate complex (triphenylantimony bis(hexa-2,4-dienoate), Ph3Sb(O2CCH=CH–CH=CH–CH3)2 (1)). A topological analysis of the electron density was carried out in the framework of the quantum theory of atoms in molecules (QTAIM), which allows to study the nature of chemical bonds and the molecular graph in Ph3Sb(O2CCH=CH–CH=CH–CH3)2 complex. The molecular graph is an important tool for determining the interacting atoms. However, the molecular graph of the triphenylantimony disorbate complex did not show the presence of the “expected” intramolecular interactions between the antimony atom and the carbonyl oxygen one. Such a situation can be caused by electron density low curvature between these atoms. It is extremely difficult case, and sometimes it is not possible to find all the “expected” bond paths and critical points (3,−1). Thus, the molecular graph for this class of compounds does not provide a definitive picture of the chemical bonding and should be complemented with other descriptors, such as а source function (SF) and non-covalent interaction (NCI) index. It was found that in some cases using the SF on the NCI isosurface allows to interpret intramolecular interactions in the absence of a bond critical point more correctly. In this article, presence of intramolecular interaction in the absence of a bond critical point between the antimony atom and the carboxylate oxygen one was shown. The carboxylate fragment always acts as a source of the electron density for the Sb…O(carbonyl) interactions, whereas the antimony atom can be both a source and a sink for it.

The addition of different substituted o-benzoquinones and o-iminobenzoquinones to tin(II) bis(o-iminophenolates) of the types (Fc-IP)2SnII and (Fc-4,6-IP)2SnII (where Fc-IP is anion 2-(ferrocenylme...

Metal tris-o-dioxolene (o-quinone, o-semiquinone, and catecholate) complexes represent an interesting and vivid model system for the demonstration of a relationship between the structure and magnetic properties when considering a series of objects of the same type. After publishing the reviews [1, 2], the metal tris-o-dioxolene complexes containing the symmetric 3,6-di-tert-butyl-o-benzoquinone derivatives with substituents in positions 4 and 5 are described in a number of works. In addition, some earlier unpublished structures of the complexes of this type are reviewed. The substituents in the lateral chains enhance the steric protection of the metal center and, as a consequence, result in the formation of coordination polyhedra uncharacteristic of the tris(dioxolene) complexes, such as a trigonal prism. In turn, the distortion of the structure affects the magnetic properties of the complexes. Only the complexes with the derivatives of sterically hindered o-quinones, 3,5- and 3,6-di-tert-butyl-o-benzoquinones, are considered in the present review. On the one hand, bulky tert-butyl groups prevent the formation of direct intermolecular contacts and, on the other hand, prevent organic reactions to occur at the benzoquinone cycle.

New 10π-electron stabilized O,N-heterocyclic germylene was synthesized and structurally characterized for the first time. Its reduction with potassium in THF resulted in a unique low-valent germanium compound comprising the conjugated Ge4 chain, which was also characterized by the single crystal X-ray analysis. Bonding aspects in the latter compound have been additionally explored by DFT calculations, which revealed the occurrence of three σ bonds of different (covalent and dative) characters between the Ge atoms.

Bis(alkyl) Sc and Y complexes activated with [Ph3C][B(C6F5)4] and AliBu3 provide 40–100% conversion of 500 equivalents of 1-heptene in 24 h to afford the polymer samples with Mn = 1.55–190.2 × 103 and Mw/Mn = 1.55–3.87.

Yb(iii), Y(iii) and Ca(ii) complexes coordinated by di- and trianionic diiminophenolate ligands.

Three new sterically hindered acridin-4-ols have been prepared by alkylation of anilines with 3,5-di-tert-butyl-6-methoxymethylcatechol followed by oxidation of the reaction mixture. Formation of the acridine moiety was found to occur in the course of oxidation of the intermediate (anilinomethyl)catechol on contact with air in the Et2O/H2O–KOH system. The molecular structure of two acridin-4-ols was determined by single-crystal X-ray diffraction.

The electron density distribution based on a whole-molecule aspherical scattering factor (molecular invariom) and an asymmetric unit-cell aspherical scattering factor (crystal invariom) allows us to analyze both intramolecular and intermolecular interactions in a crystal with sufficient accuracy.

A new mixed Eu(II)-Cu(I) iodide [Eu(DME)4][Cu2I4] (1) was synthesized by the reaction of an organosulphide salt of Eu(II) and CuI in DME media. X-ray analysis revealed that 1 is an ate-complex consisting of Eu(DME)4 dications and tetraiododicuprate dianions. Upon UV light excitation (λ = 365 nm), the compound exhibits intense double-peaked photoluminescence (PL) at 445 and 500 nm. The relative intensity of these peaks changes dramatically when the temperature changes in the range of 180-250 K. To understand the nature of the found PL thermochromism, the structure and time-resolved PL of 1 were studied at various temperatures. The time-resolved PL studies of 1 at various temperatures revealed the presence of two luminescent centers which are excited by the capture of an electron from the conduction band. The ratio of intensities at 445 and 500 nm (R = I445/I500) in the PL spectra of 1 changes by almost two orders of magnitude and the relative sensitivity S (S = (∂R/∂T)/R) exceeds 5% per K in the range of 190-245 K that makes this compound a promising luminescent thermometer for the range where ammonia exists in a liquid state.

3a,6a-Diaza-1,4-diphosphapentalene (DDP) with indium triiodide forms the [In(DDP)I3] complex (I) with the ratio In : DDP = 1 : 1. The DDP ligand reacts with antimony(III) chloride to form a coordination polymer, the treatment of which with pyridine in the presence of pyridine hydrochloride affords the [PyH]+[Sb(DDP)Cl4)]– complex (II) (CIF files CCDC nos. 1937822 (I) and 1937823 (II)). The metal is coordinated to the phosphorus atom at an angle to the plane of the heteropentalene cycle (101.9(1)° and 106.0(1)° for In and Sb, respectively). This indicates that the coordination occurs due to electrons of the heteroaromatic π system.

Ln(II) (Ln = Yb, Sm) and Ca(II) [NCsp3N] pincer type diarylmethanido complexes [2,2′-(4-MeC6H3NMe2)2CH]2M (M = Yb (2), Sm (3), Ca (4)) coordinated by a tridentate diarylmethanido ligand were synthesized through salt metathesis reactions of {[2,2′-(4-MeC6H3NMe2)2CH]K(THF)}2 and MI2(THF)2. X-ray analysis revealed that both diarylmethanido ligands in 2–4 are tridentate and coordinate to the metal centers via central carbon and two nitrogen atoms of NMe2 groups resulting in [NCsp3N] pincer coordination. In one of the five-membered MCCCN metallacycles in each tridentate diarylmethanido ligand, metal–arene interactions were detected and the coordination mode of [NCsp3N] ligands in 2–4 can be classified as κ1-N:η4-CCCN. A dynamic behavior involving the exchange between NMe2 groups and THF molecules in the coordination sphere of the M(II) ion was detected in solution. Complexes 2–4 proved to be catalytically active in a variety of reactions of C–C and C–E (E = Si, P, N, S) bond formation. Yb(II) 2 and Ca(II) 4 complexes catalyze intermolecular hydrobenzylation of styrene with 2-methyl and 2,6-dimethyl pyridines. Complex 2 demonstrates high chemo- and regioselectivities and is the first Ln(II) catalyst for intermolecular C–C bond formation. Complexes 2–4 were found to be efficient and selective precatalysts for intermolecular hydroelementation of olefins and acetylenes with various EH substrates (E = Si, P, N, S). Complexes 2–4 have demonstrated their versatility for intermolecular C–E bond formation and allow the realization of hydroamination, hydrophosphination, hydrosilylation and hydrothiolation of styrene and phenylacetylene. Moreover, 2–4 were found to be active in the catalysis of challenging transformations such as hydrosilylation and hydrophosphination of internal double CC and triple CC bonds.

The synthesis, crystal structure, thermal stability, porosity and magnetic properties of three new layered coordination polymers [(M2(pQ)3)·4DMAA]n (M3+ = La3+ (1), Pr3+ (2), Nd3+ (3); pQ2− – the dianionic form of 2,5-dihydroxy-3,6-di-tert-butyl-para-quinone; DMAA = N,N′-dimethylacetamide) are reported. The coordination polymers obtained were investigated by solid-state electrochemistry which demonstrates multistep one-electron transformations caused by the presence of redox-active dioxolene ligands.

Complexes [(2-MeOC6H4N)C(tBu)N(2,6-Me2C6H3)]2LnN(SiMe3)2 (Ln = Y (2), Sm (3)) and [(2-MeOC6H4N)C(tBu)N(2,6-Me2C6H3)]CaN(SiMe3)2(THF) (4) were obtained by reacting Ln[N(SiMe3)2]3 (Ln = Y, Sm) or Ca[N(SiMe3)2]2 with [2-MeOC6H4N]C(tBu)NH(2,6-Me2C6H3) (1) in 1 : 2 or 1 : 1 molar ratios, respectively, and were isolated in 76 (2), 68 (3) and 63% (4) yields. In complexes 2 and 3, the amidinate ligands are tridentate due to the intramolecular coordination of the 2-MeO-group to the metal center. Complex 4 exhibits an unusual κ2-N,O:η3-arene coordination mode of the amidinate ligand. Complexes 2–4 initiate ring-opening polymerization (ROP) of rac-lactide (rac-LA) and e-caprolactone (e-CL) at room temperature and allow for conversion of 1000 equivalents of monomer into polymer within 180–230 min for rac-LA and 1–7 min for e-CL. Complexes 2 and 3 enable the formation of atactic polymers (Pr = 0.52–0.58) featuring moderate polydispersities (PDI = 1.30–3.06 for polylactide; PDI = 1.48–2.84 for polycaprolactone). When 4 was applied, PDIs were somewhat narrower (1.28–2.43 for PLA; 1.24–2.48 for PCL). Application of the initiating systems 2–4/iPrOH (1 : 1) leads to the formation of the polymers having close values of the experimental and calculated molecular weights however does not affect strongly the molecular weight distribution. In the presence of 5 equivalents of iPrOH, complexes 2–4 initiate immortal polymerization for both rac-LA and e-CL. The polymers feature a good match with the experimental and calculated Mn but have moderate polydispersities (PDI = 1.28–1.90 for polylactide; PDI = 1.24–1.96 for polycaprolactone).

A series of new isolable and thermally stable half-sandwich Ln(II) benzhydryl complexes coordinated by the sterically demanding ligands tert-butylcarbazol-9-yl [tBu4Carb]Ln[(p-tBu-C6H4)2CH](L) (Ln = Sm, L = DME (4); Ln = Yb, L = DME (5); Ln = Yb, L = TMEDA (6)) and 2,7-di-tert-butyl-fluoren-9-trimethylsilylyl [2,7-tBu2-9-Me3Si-C13H6]Yb[(p-tBu-C6H4)2CH](DME) (7) were synthesized by the alkane elimination reaction of [(p-tBu-C6H4)2CH]2Ln(Ln) (Ln = Sm, Yb) with tBu4CarbH and 2,7-tBu2-9-Me3Si-C13H7. X-ray analysis revealed that in 4, 5, and 7 the benzhydryl ligand is coordinated to the metal ion in an η3 coordination mode, while in 6 it is η1-bound. The type of coordination of the benzhydryl ligands in diamagnetic 5–7 is retained in their C6D6 solutions. Complexes 4–7 demonstrated unprecedented thermal stability and do not undergo decomposition after heating their solutions in C6D6 or toluene at 100 °C for 72 h. The reactions of [tBu4Carb]Ln[(p-tBu-C6H4)2CH](DME) (Ln = Sm (4), Ln = Yb (5)) with an excess of D...

The current study provides a clear understanding of the chemical properties of annelated 3a,6a-diaza-1,4-diphosphapentalenes (DDPs), which are best viewed as stabilized singlet phosphinidenes. It w...

The synthesis of electron-deficient gallium- and aluminum-centered species containing a redox-active dpp-Bian ligand (dpp-Bian = 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene) is described. The reaction of digallane [(dpp-Bian)Ga-Ga(dpp-Bian)] with [Ph3C][PF6] or AgPF6 resulted in polyoxidized species [(dpp-Bian)GaF2]2 (1), [(dpp-Bian)H2][PF6] (2), and [(dpp-Bian)GaF(O2PF2)]2 (3). The reaction of digallane with B(C6F5)3 led to electron-deficient gallylene [(dpp-Bian)GaB(C6F5)3] 4 of a dpp-Bian radical anion. The soft oxidation of digallane with tosyl cyanide gave the trinuclear cationic species [(dpp-Bian)Ga(Tos)3Ga(Tos)3Ga(dpp-Bian)][Ga(CN)4] (5) containing dpp-Bian radical anions. The reaction of [(dpp-Bian)AlEt2] with 1 equiv of [Ph3C][B(C6F5)4] resulted in the cationic complex [(dpp-Bian)AlEt2][B(C6F5)4] (6) of neutral dpp-Bian, while the treatment of [(dpp-Bian)AlEt(Et2O)] with 1 equiv of [Ph3C][B(C6F5)4] resulted in the compound [(dpp-Bian)AlEt(Et2O)][B(C6F5)4] (7) of a dpp-Bian radical anion. The reaction of diethylaluminum derivative [(dpp-Bian)AlEt2] with 1 equiv of B(C6F5)3 gave the cationic complex [{(dpp-Bian)AlEt}2F][EtB(C6F5)3] (8) containing radical-anion dpp-Bian ligands. The paramagnetic compounds 1, 2, 4, 5, 7, and 8 were characterized by electron paramagnetic resonance spectroscopy, and the diamagnetic complex 6 was characterized by NMR spectroscopy. The molecular structures of 1-6 and 8 were established by single-crystal X-ray diffraction analysis. Compounds 4 and 6-8 were found to be active initiators for immortal ring-opening polymerization of e-caprolactone.