Search

Switching of light polarization on the sub-picosecond timescale is a crucial functionality for applications in a variety of contexts, including telecommunications, biology and chemistry. The ability to control polarization at ultrafast speed would pave the way for the development of unprecedented free-space optical links and of novel techniques for probing dynamical processes in complex systems, as chiral molecules. Such high switching speeds can only be reached with an all-optical paradigm, i.e., engineering active platforms capable of controlling light polarization via ultrashort laser pulses. Here we demonstrate giant modulation of dichroism and birefringence in an all-dielectric metasurface, achieved at low fluences of the optical control beam. This performance, which leverages the many degrees of freedom offered by all-dielectric active metasurfaces, is obtained by combining a high-quality factor nonlocal resonance with the giant third-order optical nonlinearity dictated by photogenerated hot carriers at the semiconductor band edge., (© 2024. The Author(s).)

We report the synthesis, structures, and magnetic and luminescence properties of a series of new mono- and dinuclear Er 3+ complexes derived from sterically demanding aryloxide and fluorinated alkoxide ligands: [4- t Bu-2,6-(Ph 2 CH) 2 C 6 H 2 O] 3 Er(THF) (1), [(C 6 F 5 ) 3 CO] 3 Er(Me 3 SiOH) (2), [(C 6 F 5 ) 3 CO] 3 Er[(Me 3 Si) 2 NH] (3), [(C 6 F 5 ) 3 CO] 3 Er(C 6 H 5 CH 3 ) (4), [(C 6 F 5 ) 3 CO] 3 Er( o -Me 2 NC 6 H 4 CH 3 ) (5) and {[Ph(CF 3 ) 2 CO] 2 Er(μ 2 -OC(CF 3 ) 2 Ph)} 2 (6). In compounds 1, 2, and 4, the Er 3+ ion is four-coordinated and adopts a distorted trigonal pyramidal geometry, while in 3, 5, and 6, the coordination geometry of Er 3+ is impacted by the presence of several relatively short Er⋯F distances, making them rather 6-coordinated. All compounds behave as field-induced Single Molecule Magnets (SMMs) and exhibit an Er 3+ characteristic near infrared (NIR) emission associated with the 4 I 13/2 → 4 I 15/2 transition with a remarkably long lifetime going up to 73 μs, which makes them multifunctional luminescent SMMs. The deconvolution of the NIR emission spectra allowed us to provide a direct probe of the crystal field splitting in these compounds, which was correlated with magnetic data.

Bis(carbazolide) complexes M[3,6-tBu 2 -1,8-(RC≡C) 2 Carb] 2 (THF) n (R=SiMe 3 , n=0, M=Ca, Yb; R=Ph, n=1, M=Ca, Yb; n=0, M=Yb) were synthesized through transamination reaction of M[N(SiMe 3 ) 2 ] 2 (THF) 2 with two molar equivalents of carbazoles. The complexes feature M(η 2 -C≡C) 4 structural motif composed of M(II) ions encapsulated by four acetylene fragments due to atypical for alkaline- and rare-earth metals η 2 -interactions with triple C≡C bond. This interaction is evidenced experimentally by X-ray diffraction, Raman spectroscopy in the solid state and by NMR-spectroscopy in the solution. According to QTAIM analysis there are 4 bond critical points (3;-1) between the metal atom and each of the triple bonds, which are connected by a strongly curved, almost T-shaped bond pathway., (© 2023 Wiley-VCH GmbH.)

A series of NHC-stabilized amido compounds (NHC) n M[N(SiMe 3 ) 2 ] 2 (M = Yb(II), Sm(II), Ca(II); n = 1, 2) showed remarkable catalytic efficiency in addition of PhPH 2 and PH 3 to alkenes under mild conditions and low catalyst loading. The effect of σ-donor capacity of NHCs on catalytic activity in hydrophosphination of styrene with PhPH 2 and PH 3 was revealed. For the series of three-coordinate complexes 1-4M , a tendency to increase the catalytic activity with growth of σ-donating strength of the carbene ligand was clearly demonstrated. The complex (NHC) 2 Sm[N(SiMe 3 ) 2 ] 2 (NHC = 1,3-diisopropyl-2 H -imidazole-2-ylidene) ( 5Sm ) proved to be the most efficient catalyst, which enabled hardly realizable transformations such as PhPH 2 addition across internal C═C bonds of norbornene and cis - and trans -stilbenes, providing the highest reaction rate for addition of PH 3 to styrene. Excellent regio- and chemoselectivities of alkylation of PH 3 with styrenes allow for a selective and good-yield synthesis of desired organophosphines─either primary, secondary, or tertiary. Stepwise alkylation of PH 3 with various substituted styrenes can be efficiently applied as an approach to nonsymmetric secondary phosphines. The rate equation of the addition of styrene to PH 3 promoted by 5Sm was found: rate = k [styrene] 1 [5Sm] 1 .

A series of new half-sandwich bis(alkyl) rare-earth metal complexes coordinated by a sterically demanding 1,3,6,8-tetra- tert -butyl-carbazol-9-yl ligand [ t Bu 4 Carb]La(CH 2 C 6 H 5 ) 2 (THF) (1-La), [ t Bu 4 Carb]Ln( o -NMe 2 C 6 H 4 CH 2 ) 2 (Ln = Sc (2-Sc), Y (2-Y), La (2-La), [ t Bu 4 Carb]Ln(CH 2 SiMe 3 ) 2 (THF) (Ln = Sc (3-Sc), Y (3-Y)), were synthesized. 1-La, 2-La, and 2-Y were prepared by an alkane elimination protocol, while 2-Sc, 3-Sc, and 3-Y became accessible only when salt metathesis reactions of t Bu 4 CarbK with R 2 Ln(THF) n + [BPh 4 ] - were employed. X-ray analysis revealed that in all complexes the carbazolyl ligand exhibits π-coordination with metal ions. 2-Sc and 3-Sc when activated with [Ph 3 C][B(C 6 F 5 ) 4 ] demonstrate excellent activity in α-olefin (octene-1, nonene-1, decene-1 and 1,1-diphenyl-but-1-ene) polymerization. When H 2 was used as a chain transfer agent (1 bar, rt) in the presence of 3-Sc/[Ph 3 C][B(C 6 F 5 ) 4 ] or 2-Y, 2-La olefin hydrogenation occurred with quantitative conversion.

A series of bis(alkyl) complexes {( t Bu)C[N(2,6-Me 2 C 6 H 3 )] 2 }Ln(CH 2 SiMe 3 ) 2 (THF) n (Ln = Y, n = 1 (1); Ln = Sc, n = 1 (2)), {2-[Ph 2 P(O)]C 6 H 4 NC( t Bu)N(2,6-Me 2 C 6 H 3 )}Sc(CH 2 SiMe 3 ) 2 (3), {2-[Ph 2 P(NPh)]C 6 H 4 NC( t Bu)N(2,6-Me 2 C 6 H 3 )}Sc(CH 2 SiMe 3 ) 2 (4) coordinated by bidentate (N,N) and tridentate (N,N,O; N,N,N) amidinate ligands are synthesized using an alkane elimination approach. Yttrium complex 1 demonstrated a half-life of ∼2.5 days at room temperature in benzene-D6 (C 6 D 6 ) solution, whereas scandium complexes proved to be much more stable (25 d (2), 30 d (3) and 42 d (4)). Complexes 1-4 as a part of ternary catalytic systems 1-4/TB, HNB/AlR 3 (AlR 3 = AliBu 3 , AliBu 2 H; TB = [Ph 3 C][B(C 6 F 5 ) 4 ], HNB = [PhNHMe 2 ][B(C 6 F 5 ) 4 ]) demonstrated high catalytic activity in isoprene polymerization and enable 80%-100% conversion of 1000 equivalents of monomer into polymer at 25 °C within 3-180 min. The isolated polyisoprenes feature predominantly cis -1,4-regularity (69.2%-87.3%) and polydispersities M w / M n = 2.26-8.92. Moreover, the binary (2/TB) and ternary (1-4/TB/10 AliBu 3 ) systems initiate 1-heptene polymerization providing 40%-100% conversion of 500 equivalents of monomer in 24 h at 25 °C giving polymer samples with M n = 1.55-190.2 × 10 3 and M w / M n = 1.55-3.87.

The reactions of 2-imino-2,3-dihydrobenzoxazole LH with M[N(SiMe 3 ) 2 ] 2 (THF) 2 (M = Yb and Ca) and Y(CH 2 SiMe 3 ) 3 (THF) 2 proceed with the opening of the dihydrobenzoxazole ring and the elimination of HN(SiMe 3 ) 2 or SiMe 4 . Besides, in the case of Yb[N(SiMe 3 ) 2 ] 2 (THF) 2 , an electron transfer from Yb(II) to L takes place and Yb(III) complex 1 is coordinated by a dianionic phenolate ligand containing a pendant radical-anionic diazabutadiene fragment form. When LH is reacted with Ca[N(SiMe 3 ) 2 ] 2 (THF) 2 , C-H bond activation of a methyl fragment by imino nitrogen occurs and affords a dimeric calcium complex 2. In 2, the phenolate ligand is dianionic due to the presence of the amido-imino fragment [R-NC(CH 3 )-C(CH 2 )-NR'] - (R = 2,4- t Bu 2 -C 6 H 2 O; R' = 2,6-iPr 2 C 6 H 3 ). In situ generated ate-complex {Na(Et 2 O) n }{Ca[N(SiMe 3 ) 2 ] 3 } also enables C-H bond activation, however the dianionic phenolate ligand in the resulting complex 3 contains an amido-imino fragment [R-N-C(CH 2 )-C(CH 3 )NR'] - featuring the sequence of N-C and NC bonds opposite to that in 2. The reaction of Y(CH 2 SiMe 3 ) 3 (THF) 2 with LH affords mono(alkyl) yttrium complex 4. 4 contains a dianionic amido-imino phenolate ligand resulting from the migration of one alkyl group to the CN bond [R-N-C(Me)(CH 2 SiMe 3 )-C(Me)NR']. 4 undergoes slow intramolecular C-H bond activation of the residual CH 3 group to afford a yttrium complex coordinated by a trianionic diamido-phenolate ligand [R-N-C(Me)(CH 2 SiMe 3 )-C(CH 2 )NR'].

We report the synthesis, structures, and magnetic investigations of two new octahedral dysprosium complexes, based on the original N-heterocyclic carbene (NHC) tridentate bis(phenoxide) ligand, of the respective formulas mer -[DyL(THF) 2 Cl] ( 1 ) and mer -[DyL(THF) 3 ][BPh 4 ] ( 2 ), where L = 1,3-bis(3,5-di- tert -butyl-2-oxidophenyl)-5,5-dimethyl-3,4,5,6-tetrahydropyrimidin-1-ium chloride and THF = tetrahydrofuran. The short Dy-O distances in the axial direction in association with the weak donor ability of the NHC moiety provide a suitable environment for slow relaxation of magnetization, overcoming the previous single-molecule magnets based on NHC ligands.

The catalytic activity in amine-borane dehydrogenation is shown for the first time for Ln(II) species using complexes [{( p-t Bu-C 6 H 4 ) 2 CH} 2 M·L] (M = Yb, Sm, L = (DME) 2 , TMEDA). The protonation of M(II)-C bonds with HNR 1 R 2 BH 3 affords amidoborane complexes [M(NR 1 R 2 BH 3 ) 2 L], which under excess HNMe 2 BH 3 transform to [NMe 2 BH 2 NMe 2 BH 3 ] - derivatives, both serving as the dehydrocoupling intermediates.

This article presents a study of the excited state relaxation dynamics of N -salicylidene- o -aminophenol (SOAP) in ethanol solution. Femtosecond transient absorption (TA) spectroscopy and theoretical calculations are used in combination to establish the mechanism of the excited state relaxation and type of molecular species involved in the accompanying phototransformations. TA spectra show that upon photoexcitation two SOAP tautomers ( E -enol and Z -keto) interconvert by ESIPT. The molecule can subsequently isomerize to the E -keto form of SOAP. An intriguing observation is that the TA spectra of this compound in ethanol show modulations of the signal at the stimulated emission spectral range. It is found that these modulations are due to the coherence of the excited ensemble of molecules whose evolution over time represents a moving wave packet. After Fourier transform of the modulations, two characteristic frequencies are identified. These frequencies refer to the corresponding vibrational modes of the excited state and their nature is elucidated by DFT quantum chemical calculations. The obtained experimental and theoretical data reveal the nature of the vibronic coupling between the ground and excited state and the type of molecular vibrations involved in the molecular dynamics along the potential surface of the first excited state at the initial moment right after excitation. These vibrations characterize the starting point in the excited state dynamics of the molecule toward Z - E isomerization of the keto form of SOAP. This study provides a comprehensive picture of the dynamic processes taking place upon photoexcitation of the compound, which might enable control over the various relaxation channels.

The effect of luminescent enhancement under exchange of the auxiliary ligand in Europium(III) tris(1,3-diphenyl-1,3-propanedionato) monohydrate was investigated by steady-state and time-resolved transient absorption spectroscopy. The excited state relaxation dynamics of this complex was analysed through a comparison of the experimental data obtained for several model compounds, namely Eu(DBM) 3 ·NH 3 , Eu(DBM) 3 .EDA, Eu(DBM) 3 .Phen, Al(DBM) 3 and dibenzoylmethane (DBM) in various solutions and polymer matrices. The results show there is no linear relationship between enhancement of the emission quantum yield and the luminescent lifetime, which suggests that the auxiliary ligand reduces the rate of nonradiative relaxation of the lanthanide ion, but also affects the excited state energy transfer from ligand to metal ion. Transient absorption data shows a clear correlation between the efficiency of the energy transfer and the degree of triplet state population expressed by an amplification of the signal for its excited state absorption band on going from Eu(DBM) 3 ·H 2 O to the Eu(DBM) = .L complex. The results show that this auxiliary ligand exchange acts as a "switch" turning the intersystem crossing on or off as a competitive pathway for excited state relaxation of the europium(III) complexes., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)

We report the synthesis and structures of three luminescent dysprosium(iii) complexes based on fluorinated alkoxide ligands of formulas [Dy(L1)2(THF)4][BPh4]·0.5THF (1), [Dy(L2)2(THF)5][BPh4]·2.5THF (2) and [Dy(L3)2(THF)5][BPh4]·2THF (3) (L1 = (CF3)3CO-, L2 = C6F5C6F4O-, L3 = C6F5C(CH3)O-). Despite the different dysprosium ion geometries (octahedral vs. distorted pentagonal bipyramidal), these systems exhibit a single-molecule magnet (SMM) behavior, but with distinct relaxation dynamics. Moreover, a typical dysprosium-based luminescence is observed for the three complexes, which make them bifunctional magneto-luminescent SMMs. Remarkably, complex 3 exhibits a high anisotropy barrier of 1469 cm-1 and a blocking temperature of 22 K, making it one of the most performant alkoxide-based SMMs with the highest blocking temperature for a luminescent SMM.

Small lakes in areas of intensive crude oil production may be susceptible to oil pollution arising from accidental spills and leaks, eventually leading to the pollution of bottom sediments. Effective cleaning of aquatic bottom sediments remains a challenge. Flotation is a potentially simple and reliable approach for the cleanup of bottom sediments without their excavation from the water body. Full-scale testing of flotation-based technology using the specially designed airlift plant allowed the cleaning of bottom sediments of an unnamed boreal lake ('the lake') within the Samotlor oil field, North Russia, heavily polluted with crude oil several decades ago. The lake bottom sediments are dominated by peat and unevenly polluted with oil. The average oil content in the lake bottom sediments was 111 g kg -1 . During the 1.5 months' field test in July-August 2018, the average total oil concentration in the bottom sediments of the lake was reduced to 1.99 g kg -1 . Secondary water contamination was minimal; the content of oil hydrocarbons in the water after completion of work did not exceed 0.09 ± 0.04 mg L -1 . This study demonstrates that flotation-based technology can be applied for in situ cleaning of oil-contaminated lake bottom sediments including those in boreal climates.

First Ln(ii) ring-expanded NHC complexes (er-NHC)Ln[N(SiMe3)2]2 (Ln = Sm, Yb) are synthesized and proved to be highly efficient pre-catalysts for the intermolecular hydrophosphination of such indolent substrates as 1-alkenes, cyclohexene and norbornene.

We report here the synthesis, structure, magnetic and photoluminescent properties of three new bifunctional Schiff-base complexes [Dy(L 1 ) 2 (py) 2 ][B(Ph) 4 ]⋅py (1), [Dy(L 1 ) 2 Cl(DME)] ⋅ 0.5DME (2) and [Dy(L 2 ) 2 Cl] ⋅ 2.5(C 7 H 8 ) (3) (HL 1 =Phenol, 2,4-bis(1,1-dimethylethyl)-6-[[(2-methoxy-5-methylphenyl)imino]methyl]; HL 2 =Phenol, 2,4-bis(1,1-dimethylethyl)-6-[[(2-methoxyphenyl)imino]methyl]). The coordination environment of the Dy 3+ ion and the direction of the anisotropic axis may be controlled by the combination of the substituent groups of the Schiff bases, the nature of the counter-ions (Cl - vs. BPh 4 - ) and the coordinative solvent molecules. A zero-field slow relaxation of the magnetization is evidenced for all complexes but strong differences in the relaxation dynamics are observed depending on the Dy 3+ site geometry. In this sense, complex 1 exhibits an anisotropy barrier of 472 cm -1 , which may be favourably compared to other related examples due to the shortening of the Dy-O bond in the axial direction. Besides, the three complexes exhibit a ligand-based luminescence making them as bifunctional magneto-luminescent systems., (© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

We report the synthesis, structure and magnetic properties investigations of a series of new dysprosium heteroleptic mono- and dinuclear complexes based on the association of chloride and different diazabutadiene (DAD2R = [2,6-iPr2C6H3N-CR[double bond, length as m-dash]CR-NC6H3iPr2-2,6]; R = H, Me) ligands showing different redox states. While using dianionic DAD2R ligands affords the formation of dichloro-bridged dinuclear complexes [Dy2(DAD2R)(μ-Cl)2(THF)2] (R = H (1), Me (2)), two different mononuclear complexes of general formula [DyCl2(DAD2R)(THF)2] (R = H (3), Me (4)) could be obtained with either a radical monoanionic and a monoanionic DAD2R state, respectively. Remarkably, all the complexes exhibit a slow relaxation of their magnetization where the relaxation dynamics depends on both the nuclearity of the system and the DAD2R redox state.

We report the synthesis, photoluminescence and magnetic properties of two octahedral dysprosium complexes [DyR2(py)4][BPh4]·2py (1) and [DyR2(THF)4][BPh4] (2) (R = carbazolyl, py = pyridine, THF = tetrahydrofuran) exhibiting a quasi linear N-Dy-N angle in the axial direction, suitable for providing a coordination environment allowing the zero-field slow relaxation of magnetization.

New neutral bis(alkyl) Sc and Y complexes [N,Npy,N-]Ln(CH2SiMe3)2(THF)n [n = 0, Ln = Sc (1Sc), Y (1Y); n = 1, Ln = Y (1YTHF)] stabilized by a tridentate monoanionic amidopyridinate ligand were straightforwardly prepared by alkane elimination, upon mixing ligand [N,Npy,N-]H and metal precursor Ln(CH2SiMe3)3(THF)2 in toluene at 0 °C. Depending on the work-up conditions, yttrium bis(alkyl)s were isolated as either a pentacoordinate Lewis base free complex [N,Npy,N-]Y(CH2SiMe3)2 (1Y) or as a hexacoordinate THF adduct [N,Npy,N-]Y(CH2SiMe3)2THF (1YTHF). For the smaller Sc ion the only solvent-free complex [N,Npy,N-]Y(CH2SiMe3)2 (1Sc) was isolated as a pentacoordinate species irrespective of the reaction/work-up/crystallization conditions applied. Complexes 1Ln (Ln = Y, Sc) and 1YTHF were scrutinized as pre-catalysts in ternary catalytic systems Ln/borate/AliBu3 (borate = [HNMe2Ph][B(C6F5)4] or [Ph3C][B(C6F5)4]), applied to isoprene (IP) polymerization, providing moderate activity albeit high selectivity with predominant formation of 1,4-cis polyisoprene (up to 99%). The same complexes proved to be effcient catalysts also for the intermolecular hydrolelementation of styrene with various EH sustrates (pyrrolidine, morpholine, Ph2PH, PhPH2, PhSH) affording linear anti-Markovnikov addition products exclusively. After a preliminary activation by B(C6F5)3, selected bis(alkyl) complexes from this series have been finally used as valuable pre-catalysts for the CO2 hydrosylilation to CH4 in the presence of organosilanes as reducing agents (PhMe2SiH, PhSiH3, Et2MeSiH).

We report the investigation of synthesis, structure and magnetic properties of a series of homoleptic Ln(iii) complexes coordinated by radical-anionic iminopyridine ligands of general formula [Ln(IPy) 3 ]·solv (IPy = iminopyridine; Ln = Tb, Dy, Er, Y, Gd). The dysprosium analogue exhibits a zero-field Single-Molecule Magnet (SMM) behavior.

The amine elimination reaction of equimolar amounts of ansa-bis(amidine) C 6 H 4 -1,2-{NC(tBu)NH(2,6-iPr 2 C 6 H 3 )} 2 (L 1 H) and [(Me 3 Si) 2 N] 2 Yb(THF) 2 affords a bis(amidinate) Yb II complex [C 6 H 4 -1,2-{NC(tBu)N(2,6-iPr 2 C 6 H 3 )} 2 ]Yb(THF) (1) in 68% yield. Complex 1 features a rather rare η 1 -amido:η 6 -arene coordination of both amidinate fragments to the Yb II ion, resulting in the formation of a bent bis(arene) structure. Oxidation of 1 by I 2 regardless of the molar ratio of reagents (2 : 1 or 1 : 1) leads to the formation of the Yb III species [{(2,6-iPr 2 C 6 H 3 )[double bond, length as m-dash]NC(tBu)NH}-C 6 H 4 -1,2-{NC(tBu)N(2,6-iPr 2 C 6 H 3 )}]YbI 2 (THF) 2 (2) in which only one amidinate fragment is coordinated to the ytterbium ion in κ 2 -N,N'-chelating coordination mode, while the second NCN fragment is protonated in the course of the reaction and is not bound to the metal ion. The outcome of the salt metathesis reaction of LaCl 3 with lithium amidinates [C 6 H 4 -1,2-{NC(tBu)N(2,6-R 2 C 6 H 3 )} 2 Li 2 ] (R = Me, iPr) is proven to be strongly affected by the substituent 2,6-R 2 C 6 H 3 on the amidinate nitrogens. When R = iPr, the salt metathesis reaction occurs smoothly and results in the formation of an ate-chloro-amidinate complex [C 6 H 4 -1,2-{NC(tBu)N(2,6-iPr 2 C 6 H 3 )} 2 ]La(μ 2 -Cl)Li(THF)(μ 2 -Cl) 2 Li(THF) 2 (3) in which the La III ion is coordinated by both amidinate fragments in a "classic"κ 2 -N,N'-chelating fashion. In the case of R = Me, the reaction requires prolonged heating for completion. Moreover, the salt metathesis reaction is accompanied by the fragmentation of the ligand and affords a trinuclear chloro-amidinate complex [C 6 H 4 -1,2-{NC(tBu)N(2,6-Me 2 C 6 H 3 )} 2 ]La{[(tBu)C(N-2,6-Me 2 C 6 H 3 ) 2 ]La(THF)} 2 (μ 2 -Cl) 4 (μ 3 -Cl) 2 (4) containing one dianionic ansa-bis(amidinate) and two monoanionic [(tBu)C(N-2,6-Me 2 C 6 H 3 ) 2 ] amidinate fragments. DFT calculations are conducted to determine the factor that governs this change in coordination mode and, in particular, the effect of the metal oxidation state.

Correction for 'Amido Ca(ii) complexes supported by Schiff base ligands for catalytic cross-dehydrogenative coupling of amines with silanes' by Natalia V. Forosenko et al., Dalton Trans., 2018, 47, 12570-12581.

A series of Ln(II) and Ca(II) bis(alkyl) complexes with bulky benzhydryl ligands, [( p- tBu-C 6 H 4 ) 2 CH] 2 M(L n ) (M = Sm, L = DME, n = 2 (1); M = Sm, Yb, Ca, L = TMEDA, n = 1 (2, 3, 4), were synthesized by the salt-metathesis reaction of MI 2 (THF) n ( n = 0-2) and [( p- tBu-C 6 H 4 ) 2 CH] - Na + . In complex 1, the benzhydryl ligands are bound to the metal center in η 2 -coordination mode. Unlike complex 1, in isomorphous complexes 3 and 4, due to the coordination unsaturation of the metal center, the both benzhydryl ligands coordinate to the metal in η 3 -fashion. In complex 2, one ligand is η 3 -coordinated while the second one is η 4 -coordinated to the Sm(II) ion. Complexes 2-4 demonstrated unprecedented thermal stability: no evidence of decomposition was observed after heating their solutions in C 6 D 6 at 100 °C during 72 h. Complex 1 behaves differently: thermolysis in C 6 D 6 solution at 75 °C results in total decomposition in 8 h. Addition of DME promotes decomposition of 2-4 and makes it feasible at 40 °C. Complexes 1-4 demonstrated high catalytic activity and excellent regio- and chemoselectivities in intermolecular hydrophosphination of double and triple C-C bonds with both primary and secondary phosphines. Complexes 2 and 3 enable addition of PhPH 2 toward the internal C═C bond of Z- and E-stilbenes with 100% conversion under mild conditions. Double sequential hydrophosphination of phenylacetylene with Ph 2 PH and PhPH 2 was realized due to the application of Yb(II) complex as a catalyst.

The first example of intermolecular hydrophosphination of styrene, 2-vinylpyridine and phenylacetylene with PH 3 catalyzed by bis-(amido) complexes [(Me 3 Si) 2 N] 2 M(NHC) 2 (M=Ca, Yb, Sm) coordinated by NHC ligands is described. The reactions of styrene with PH 3 proceed under mild conditions in quantitative yields to afford only anti-Markovnikov product and allow for the chemoselective synthesis of primary, secondary and tertiary phosphines. Addition of phenylacetylene to PH 3 regardless the initial molar substrates ratio results in the exclusive formation of a tertiary tris-(Z-styryl)-phosphine. Crucial effect of the Lewis base coordinated to the metal ion in precatalyst on catalytic activity in styrene hydrophosphination with PH 3 was demonstrated. Free NHCs were also found to be able to promote addition of PH 3 to styrene, however they provide much lower reaction rates compared to the metal complexes., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The synthesis, and magnetic and photoluminescence investigations of two bifunctional dysprosium complexes based on tridentate Schiff base ligands is reported. Magnetic investigations reveal a genuine single-molecule magnet (SMM) behavior, with out-of-phase signals up to 60 K, and tunable emission arising from the Schiff base ligands., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

We report the synthesis and magnetic investigation of a dysprosium pentagonal bipyramidal complex [Dy(THF)5Cl2][BPh4] (1) exhibiting a linear Cl-Dy-Cl sequence suitable for providing a coordination environment allowing a zero-field slow relaxation of the magnetization. Besides, the complex also shows dual luminescence originating from [BPh4]- and Dy3+.

A series of amido Ca complexes LCa[N(SiMe3)2](THF) (1-4) coordinated by Schiff base ligands L1-4 were synthesized via an amine elimination reaction between proligands L1-4H and a bisamido complex Ca[N(SiMe3)2]2(THF)2 in good yield. Unlike Ca[N(SiMe3)2]2(THF)2, the reactions of M[N(SiMe3)2]2(THF)2 (M = Yb, Sm) with proligands L1-4H do not lead to the formation of the target Ln(ii) amido complexes. The reaction of Yb[N(SiMe3)2]2(THF)2 with L1H is accompanied by intramolecular C-H bond activation of a quinoline ring and results in the formation of complex 6 coordinated by a new trianionic [NNNNOO] ligand. The reactions of amido complexes 1 and 4 with PhSiH3 do not allow for preparing the related hydrides but afford homoleptic bis(phenolate) complexes 5 and 7 due to a ligand redistribution reaction. Amido complexes 1-4 were evaluated as precatalysts for cross-dehydrogenative coupling of silanes (PhSiH3, Ph(Me)SiH2, and Ph3SiH) and aliphatic, aromatic and cyclic amines (RNH2 and R2NH).

We report on the synthesis, structure and investigation of magnetic properties of a series of six heteroleptic complexes of the general formula [Ln(Tpm)X3]·yMeCN (Tpm = tris(3,5-dimethylpyrazolyl)methane; Ln = Tb, Dy, Er; X- = NO3-, Cl- and y = 1 or 2). We demonstrate that the observation of a field-induced slow relaxation of magnetization is highly dependent on the anion's nature. While nitrate moieties appear to be suitable to stabilize the oblate electronic density of Dy3+, chloride ions generate an equatorial crystal-field allowing the slow relaxation of the prolate Er3+ ions.

A series of amido Ca and Yb(II) complexes LM[N(SiMe 3 ) 2 ](THF) (1Yb, 1-4Ca) coordinated by amidine-amidopyridinate ligands L 1-4 were synthesized via a transamination reaction between proligands L 1-4 H and bisamido complexes M[N(SiMe 3 ) 2 ] 2 (THF) 2 (M = Yb, Ca). The reactions of Yb[N(SiMe 3 ) 2 ] 2 (THF) 2 with proligands L 2 H-L 4 H containing CF 3 and C 6 H 4 F fragments do not allow for preparing the target Yb(II) complexes, while the Ca analogues were synthesized in good yields. Complexes 1Yb and 1-4Ca were evaluated as precatalysts for hydrophosphination of styrene, p-substituted styrenes, α-Me-styrene, and 2,3-dimethylbutadiene with various primary and secondary phosphines (PhPH 2 , 2,4,6-Me 3 C 6 H 2 PH 2 , 2-C 5 NH 4 PH 2 , Ph 2 PH, Cy 2 PH). Complexes 1Yb, 1-4Ca performed high catalytic activities in styrene hydrophosphination with PhPH 2 and Ph 2 PH and demonstrated high regioselectivity affording exclusively the anti-Markovnikov addition products. For primary PhPH 2 the reactions (1:1 molar ratio of substrates) catalyzed by 1Yb, 1Ca, and 2Ca proved to be highly chemoselective affording the secondary phosphine Ph(PhCH 2 CH 2 )PH; however, complexes 3Ca and 4Ca led to the formation of both secondary and tertiary phosphines in 80:20 and 86:14 ratios. Styrene hydrophosphinations with 2,4,6-Me 3 C 6 H 2 PH 2 and 2-pyridylphosphine for all complexes 1Yb and 1-4Ca proceeded much more slowly compared to PhPH 2 . Addition of 2-C 5 NH 4 PH 2 to styrene catalyzed by complex 1Yb turned out to be non-regioselective and led to the formation of a mixture of Markovnikov and anti-Markovnikov addition products, while all Ca complexes enabled regioselective anti-Markovnikov addition. Complexes 1Ca and 1Yb containing catalytic centers featuring similar ionic radii performed different catalytic activity: the ytterbium analogue proved to be a more active catalyst for intermolecular hydrophosphination of styrene with Cy 2 PH, 2-C 5 NH 4 PH 2 , and PhPH 2 , but less active with sterically demanding 2,4,6-Me 3 C 6 H 2 PH 2 . Styrenes containing in p-position electron-donating groups (Me, tBu, OMe) performed with noticeably lower rates in the reactions with PhPH 2 compared to styrene. Complexes 1Yb, 1Ca, 2Ca, 3Ca, and 4Ca enabled addition of PhPH 2 toward the double C═C bond of α-Me-styrene, and the reaction rate for this substrate is noticeably lower; however quantitative conversions were reached in ∼40 h. Complexes 1Ca and 2Ca promoted 1,2-addition of PhPH 2 to 2,3-dimethyl butadiene with excellent regio- and chemoselectivity to afford linear secondary phosphines. Hydrophosphination of inert 1-nonene with Ph 2 PH with 40% conversion becomes possible due to the application of complex 2Ca (40 h, 70 °C). The rate law for the hydrophosphination of styrene with Ph 2 PH catalyzed by 1Ca was found to agree with the idealized equation: v = k[styrene] 1 [1Ca] 1 .

A systematic study of reactions between Cp* 2 Yb(THF) (Cp* = η 5 -C 5 Me 5 , 1) and iminopyridine ligands (IPy = 2,6- i Pr 2 C 6 H 3 N[double bond, length as m-dash]CH(C 5 H 3 N-R), R = H (2a), 6-C 4 H 3 O (2b), 6-C 4 H 3 S (2c), 6-C 6 H 5 (2d)) featuring similar electron accepting properties but variable denticity and steric demand, has provided a new example of steric control on the redox chemistry of ytterbocenes. The reaction of the unsubstituted IPy 2a with 1, either in THF or toluene, gives rise to the paramagnetic species Cp* 2 Yb III (IPy)˙ - (3a) as a result of a formal one-electron oxidation of the Yb II ion along with IPy reduction to a radical-anionic state. The reactions of 1 with substituted iminopyridines 2b-d, bearing aryl or hetero-aryl dangling arms on the 6 position of the pyridine ring occur in a non-coordinating solvent (toluene) only and afford coordination compounds of a formally divalent ytterbium ion, coordinated by neutral IPy ligands Cp* 2 Yb II (IPy) 0 (3b-d). The X-ray diffraction studies revealed that 2a-c act as bidentate ligands; while the radical-anionic IPy in 3a chelates the Yb III ion with both nitrogens, neutral IPy ligands in 3b and 3c participate in the metal coordination sphere through the pyridine nitrogen and O or S atoms from the furan or thiophene moieties, respectively. Finally, in complex 3d the neutral IPy ligand formally adopts a monodentate coordination mode. However, an agostic interaction between the Yb II ion and an ortho C-H bond of the phenyl ring has been detected. Imino-nitrogens in 3b-d are not involved in the metal coordination. Variable temperature magnetic measurements on 3a are consistent with a multiconfigurational ground state of the Yb ion and suggest that the largest contribution arises from the 4f 13 -radical configuration. For complexes 3b and 3c the data of magnetic measurements are indicative of a Yb II -closed shell ligand electronic distribution. Complex 3d is characterized by a complex magnetic behavior which does not allow for an unambiguous estimation of its electronic structure. The results are rationalized using DFT and CSSCF calculations. Unlike diazabutadiene analogues, 3a does not undergo a solvent mediated metal-ligand electron transfer and remains paramagnetic in THF solution. On the other hand, complexes 3b-d readily react with THF to afford 1 and free IPy 2b-d.

Lithium silylamides 1,8-C 10 H 6 [N(SiMe 3 )Li(L)] 2 (L = Et 2 O (); L = TMEDA (1TMEDA)), when treated with PhC[triple bond, length as m-dash]N, formed the adducts 1,8-C 10 H 6 [N(SiMe 3 )Li(N[triple bond, length as m-dash]CPh)(OEt 2 )][N(SiMe 3 )Li(OEt 2 )] () and 1,8-C 10 H 6 [N(SiMe 3 )Li(N[triple bond, length as m-dash]CPh)][N(SiMe 3 )Li(TMEDA)] (2TMEDA) containing one benzonitrile molecule coordinated to Li ion while the second molecule retains a coordinated L ligand. The salt metathesis reactions of LnCl 3 (Ln = Y, Sm) with equimolar amounts of and 2TMEDA (THF, 4 h, 40 °C) resulted in benzonitrile insertion and formation of new dianionic amido-amidinate ligands. The reactions of with LnCl 3 afforded ionic chloro complexes [{1,8-C 10 H 6 [NSiMe 3 ][NC(Ph)NSiMe 3 ]}{1,8-C 10 H 6 [N(H)SiMe 3 ][NC(Ph)NSiMe 3 ]}LnCl][Li(L) n ] (Ln = Y, L = THF, n = 4 (3Y), Ln = Sm, L = DME, n = 3 (3Sm)), while the reaction of 2TMEDA and YCl 3 leds to the formation of the neutral salt-free yttrium chloro complex {1,8-C 10 H 6 [NSiMe 3 ][NC(Ph)NSiMe 3 ]}YCl(TMEDA) (4). The treatment of 3Y and 4 with tBuOK enabled the synthesis of tert-butoxides [{1,8-C 10 H 6 [NSiMe 3 ][NC(Ph)NSiMe 3 ]}{1,8-C 10 H 6 [N(H)SiMe 3 ][NC(Ph)NSiMe 3 ]}YOtBu][Li(THF) 4 ] (7) and {1,8-C 10 H 6 [NSiMe 3 ][NC(Ph)NSiMe 3 ]}YOtBu(TMEDA) (8). Complexes 7 and 8 were evaluated as initiators for the ring opening polymerization of rac-lactide. Neutral tert-butoxide complex 8 demonstrated significantly higher activity compared to that of ionic 7.

We report a new approach for the synthesis of multifunctional Au core@Prussian Blue analogous (PBA) shell nanoheterostructures that involves PBA shell growth on the surface of cyanide-stabilized gold nanoparticles. It permits the assembly of Au@KNi II [Fe II (CN) 6 ] core@shell and Au@KNi II [Fe II (CN) 6 ]@KNi II [Cr III (CN) 6 ] core@shell@shell heterostructures with well-defined and size-controlled gold cores and PBA shells. These heterostructures exhibit tunable size- and shape-dependent magnetic and optical properties: (i) the surface plasmon resonance band position and intensity mainly depend on the PBA shell thickness, and (ii) the magnetic properties (the transition temperature, the coercivity, and magnetic regime) depend in a complex manner on the thickness as well as the particular morphology of the magnetic shell., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Here, we report the synthesis and magnetic properties investigation of a series of new organometallic homoleptic complexes Li(DME) 3 [Ln(DAD) 2 ] (Ln = Dy (1a, 1b), Tb(2), and Er(3)) based on paramagnetic Ln(iii) ions coordinated by an ene-diamido[2,6-iPr 2 C 6 H 3 N-CH[double bond, length as m-dash]CH-NC 6 H 3 iPr 2 -2,6] 2- (DAD) ligand. Dy-based compounds exhibit a genuine single-molecule magnet (SMM) behaviour, while the Tb 3+ analogue shows a field-induced slow relaxation of the magnetisation.

The half-sandwich tetra-tert-butylcarbazol-9-yl iodo complex [(tBu 4 Carb)Sm(μ-I)(THF) 2 ] 2 (1) was synthesized by the salt metathesis reaction of tBu 4 CarbK and SmI 2 (THF) 2 in THF. Complex 1 along with metallic Cu was also isolated from the oxidation reaction of (tBu 4 Carb) 2 Sm by CuI. The formation of stable radical tBu 4 Carb . was detected in this non-conventional process, indicating preferential oxidation of anion tBu 4 Carb - vs. Sm II . The treatment of 1 with two equivalents of dibenzo-18-crown-6 resulted in heterolytic dissociation of a η 5 -bond Sm-tBu 4 Carb and afforded an ionic compound [tBu 4 carb - ][SmI(crown)(THF) 2 ] + (4). Alkylation of 1 with o-NMe 2 C 6 H 4 CH 2 K (1:2 molar ratio) in THF allowed for the synthesis of half-sandwich Sm II alkyl complex (tBu 4 Carb)SmCH 2 (o-NMe 2 C 6 H 4 CH 2 )(THF) 2 (5) in 55 % yield. The amido complex (tBu 4 Carb)SmN(SiMe 3 ) 2 (DME) (6) was obtained by the reaction of 1 with two molar equivalents of NaN(SiMe 3 ) 2 in THF in 89 % yield., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

This review covers recent achievements in the intermolecular hydrophosphination and hydroamination of alkenes, dienes and alkynes catalyzed by organolanthanides.

A series of new tridentate amidines 2-[Ph 2 P[double bond, length as m-dash]X]C 6 H 4 NHC(tBu)[double bond, length as m-dash]N(2,6-R 2 C 6 H 3 ) (X = O, R = iPr (1); X = S, R = Me (2); X = NPh, R = Me (3); X = N(2,6-Me 2 C 6 H 3 ), R = Me (4)) bearing various types of donor Ph 2 P[double bond, length as m-dash]X groups in a pendant chain was synthesized. Bis(alkyl) complexes {2-[Ph 2 P[double bond, length as m-dash]X]C 6 H 4 NC(tBu)N(2,6-R 2 C 6 H 3 )}Ln(CH 2 SiMe 3 ) 2 (Ln = Y, X = O, R = iPr (5); Ln = Er, X = O, R = iPr (6); Ln = Lu, X = O, R = iPr (7); Ln = Y, X = NPh, R = Me (8); Ln = Lu, X = NPh, R = Me (9); Ln = Lu, X = N(2,6-Me 2 C 6 H 3 ), R = Me (10)) were prepared using alkane elimination reactions of 1, 3 and 4 with Ln(CH 2 SiMe 3 ) 3 (THF) 2 (Ln = Y, Er, Lu) in toluene and were isolated in 45 (5), 62 (6), 56 (7), 65 (8), 60 (9), and 60 (10) % yields respectively. The X-ray diffraction studies showed that complexes 6-8 are solvent free and feature intramolecular coordination of the P[double bond, length as m-dash]X (X = O, NPh) group to the lanthanide ions. The ternary systems 5-10/borate/AlR 3 (borate = [PhNHMe 2 ][B(C 6 F 5 ) 4 ], [Ph 3 C][B(C 6 F 5 ) 4 ], AlR 3 = AliBu 3 , AliBu 2 H; molar ratio = 1/1/10 or 1/1/1, toluene) proved to be active in isoprene polymerization and enable complete conversion of 1000-10 000 equivalents of the monomer into a polymer at 25 °C within 0.5-24 h affording polyisoprenes with polydispersities M w /M n = 1.22-3.18. A comparative study of the catalytic performance of the bis(alkyl) complexes coordinated by tridentate amidinate ligands containing different pendant donor groups demonstrated that replacement of the Ph 2 P[double bond, length as m-dash]O group by Ph 2 P[double bond, length as m-dash]NPh leads to a switch of stereoselectivity in isoprene polymerization from cis-1,4 (up to 98.5%) to trans-1,4 (up to 84.8%). And conversely introduction of methyl substituents in the 2,6 positions of the phenyl group of the Ph 2 P[double bond, length as m-dash]NPh fragment allows us to restore the 1,4-cis stereoselectivity of the catalytic systems based on bis(alkyl) complex 10 (up to 86.4%).

Heteroleptic Ln(II) and Ca(II) amides [tBuC(NC6H3-iPr2-2,6)2]MN(SiMe3)2(THF) (M = Yb (1Yb), Ca (1Ca)), [2-MeOC6H4NC(tBu)N(C6H3-iPr2-2,6)]LnN(SiMe3)2(THF) (Ln = Sm (2Sm), Yb (2Yb)), and [2-Ph2P(O)C6H4NC(tBu)N(C6H3-Me2-2,6)]YbN(SiMe3)2(THF) (3Yb) coordinated by bi- and tridentate amidinate ligands were obtained by the amine elimination reactions of M[N(SiMe3)2](THF)2 (M = Yb, Sm, Ca) with parent amidines in good yields. Complex [tBuC(NC6H3-iPr2-2,6)2]SmN(SiMe3)2 can be obtained only by a salt metathesis reaction of [tBuC(NC6H3-2,6-iPr2)2]SmI(THF)2 with NaN(SiMe3)2. Unlike 1Yb and 1Ca in 1Sm the amidinate ligand is coordinated to metal ion in κ(1)-amido:η(6)-arene fashion preventing THF coordination. The derivatives of tridentate amidinate ligands bearing pendant donor 2-MeOC6H4 or 2-Ph2P(O)C6H4N groups feature nonconventional κ(1)-N,κ(2)-O,η(6)-arene coordination mode. Complexes 1Ca, 1Sm, 1Yb, 2Sm, 2Yb, and 3Yb proved to be efficient catalysts for styrene hydrophosphination with PhPH2 and Ph2PH. In styrene hydrophosphination with PhPH2 all the catalysts perform excellent chemoselectivity and afford a monoaddition product-secondary phosphine (PhCH2CH2)PhPH. Moreover, all the catalysts perform hydrophosphination reactions regioselectively with exclusive formation of the anti-Markovnikov addition product. Within the series of complexes coordinated by the same amidinate ligand catalytic activity decreases in the following order 1Ca ≥ 1Sm>1Yb. The turnover frequencies were in the range of TOF ≈ 0.3-0.7 h(-1). However, application of tridentate amidinate ligand allowed one to increase catalytic activity significantly: for 2Sm TOF was found to be 8.3 h(-1). For the addition of PhPH2 to para-substituted styrenes catalyzed by 2Sm it was found that electron-withdrawing substituents (Cl, F) do not affect the reaction rate while electron-donating groups (tBu, OMe) noticeably slow down the reaction.

A new tridentate amidine 2-[Ph2P(O)]C6H4NHC(tBu)[double bond, length as m-dash]N(2,6-Me2C6H3) (1) bearing a side chain pendant Ph2P[double bond, length as m-dash]O group was synthesized and proved to be a suitable ligand for coordination to rare-earths ions. Bis(alkyl) complexes {2-[Ph2P(O)]C6H4NC(tBu)N(2,6-Me2C6H3)}Ln(CH2SiMe3)2(THF)n (Ln = Y, n = 1 (3), Ln = Er, n = 1 (4), Ln = Lu, n = 0 (5)) were prepared using alkane elimination reactions of and Ln(CH2SiMe3)3(THF)2 (Ln = Y, Er, Lu) in hexane and were isolated in 50, 70 and 75% yields respectively. The X-ray studies revealed that complexes 2-5 feature intramolecular coordination of P[double bond, length as m-dash]O groups to metal ions. The lutetium complex 5 proved to be rather stable: at 20 °C its half-life time is 1155 h, while for the yttrium analogue the half-life time was found to be 63 h. Complexes 3-5 were evaluated as precatalysts for isoprene polymerization. The systems Ln/borate/AliBu3 (Ln = 3-5, borate = [PhNHMe2][B(C6F5)4], [Ph3C][B(C6F5)4]) turned out to be highly efficient in isoprene polymerization and enable complete conversion of 1000-10,000 equivalents of monomer into polymer at 20 °C within 0.5-2.5 h affording polyisoprenes with a very high content of 1,4-cis units (up to 96.6%) and from narrow (1.49) to moderate (3.54) polydispersities. A comparative study of catalytic performance of the related bis(alkyl) yttrium complexes supported by amidinate ligands of different denticities and structures [tBuC(N-2,6iPr2C6H4)2](-), [tBuC(N-2,6-iPr2C6H4)(N-2-MeOC6H4)](-) and {2-[Ph2P(O)]C6H4NC(tBu)N(2,6-Me2C6H3)}(-) demonstrated that the introduction of a pendant donor group (2-MeOC6H4 or Ph2P(O)) into a side chain of amidinate scaffolds results in a significant increase in catalytic activity. The amidinate ligand bearing a Ph2P(O)-group provides a high isoprene polymerization rate along with excellent control over regio- and stereoselectivities and allows us to obtain polyisoprenes with a reasonable molecular weight distribution.

We present a new mononuclear half-sandwich complex, [Cp*Yb(DAD)(THF)]·C7H8 (1), based on a paramagnetic Yb(III) ion coordinated by diamagnetic Cp* and enediamido[2,6-Me2C6H3NCH═CHNC6H3Me2-2,6](2-) (DAD) ligands exhibiting field-induced single-ion-magnet behavior.

Metallacyclic neutral and ionic yttrium alkyl complexes coordinated by a dianionic ene-diamido ligand ([2,6-iPr2C6H3NC(Me)=C(Me)NC6H3iPr2-2,6] = L(1)) [L(1)]Y(CH2SiMe3)(THF)2 (2), {[L(1)]Y(CH2SiMe3)2}(-){Li(THF)4}(+) (3), [L(1)]Y(OEt2)(μ-Me)2Li(TMEDA) (4) were synthesized using a salt-metathesis approach starting from the related chloro complex [L(1)]Y(THF)2(μ-Cl)2Li(THF)2 (1) in 70, 85 and 72% yields respectively. The reactions of 2 with H2 or PhSiH3 afford the dimeric hydride {[L(1)]Y(THF)(μ-H)}2(μ-THF) (5) containing two μ-bridging hydrido and one μ-bridging THF ligands (91 and 85% yields). The X-ray studies of complexes 2, 3 and 5 revealed η(2)-coordination of the C=C fragment of an ene-diamido ligand to a Y cation. DFT calculations were carried out to give an insight into the metal-ligand bonding and especially the interaction between the metal and the ene-diamido ligand. The observed bonding of the ene-diamido fragment is found to reflect the acidity of the metal center in the complex that is partially overcome by a better donation from the double bond (better overlap with an empty d orbital at the yttrium center). The treatment of complex 4 with DME resulted in the C-O bond cleavage of DME and afforded a three nuclear methoxide oxide complex [{[L(1)]Y}3(μ(2)-OMe)3(μ(3)-O)](2-)[Li(DME)3](+)2 (6). Complexes 2, 3, 5 and 7 proved to be efficient precatalysts for the intermolecular hydrophosphination of styrene, 4-vinylpyridine, and 1-nonene with PhPH2 and Ph2PH as well as hydroamination of styrene and pyrrolidine.

Stable heteroleptic amido Yb(II) and Sm(II) complexes bearing aminoether-phenolate ligands and devoid of coordinated solvent have been structurally characterized. They afford highly active, chemoselective and, in the case of monoadditions, 100 % anti-Markovnikov regiospecific catalysts (down to 0.04 mol % loading) for the hydrophosphination of styrene with PhPH2 under mild conditions., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The first neutral rare-earth metal dinuclear dihydrido complexes [(NPNPN)LnH2]2 (2-Ln; Ln = Y, Lu; NPNPN: N[Ph2PNC6H3((i)Pr)2]2) bearing μ2-bridging hydride ligands have been synthesized. In the presence of THF, 2-Y undergoes intramolecular activation of the sp(2) C-H bond to form dinuclear aryl-hydride complex 3-Y containing three μ2-bridging hydride ligands.

The reaction of Ap(9Me)Lu(CH2SiMe3)2(thf) (Ap(9Me) = (2,4,6-trimethylphenyl)[6-(2,4,6-triisopropylphenyl)pyridine-2-yl]amido ligand) with two molar equivalents of PhSiH3 affords a trinuclear alkyl-hydrido cluster [(Ap(9Me)Lu)3(μ(2)-H)3(μ(3)-H)2(CH2SiMe3)(thf)2]. The analogous reactions with Ap(9Me)Ln(CH2SiMe3)2(thf) (Ln = Y, Yb) are more complex and result in the formation of mixtures of two types of trinuclear alkyl-hydrido complexes [(Ap(9Me)Ln)3(μ(2)-H)3(μ(3)-H)2(CH2SiMe3)(thf)2] and [(Ap(9Me)Ln)3(μ(2)-H)3(μ(3)-H)2(CH2SiH2Ph)(thf)2] differing in the alkyl group. The DFT calculations of [(Ap*Y)3(μ(2)-H)3(μ(3)-H)2(CH2SiMe3)(thf)2] (Ap* = (2,6-diisopropylphenyl)[6-(2,4,6-triisopropylphenyl)pyridine-2-yl]amido ligand) confirm localization of the HOMO on the Ap*-Y(1A)-CH2SiMe3 fragment, thus explaining its enhanced reactivity. Analysis of the electron density distribution reveals the Y-H and H-H bonding interactions in the (Y)3(μ(2)-H)3(μ(3)-H)2 moiety. The NMR studies of diamagnetic complexes [(Ap(9Me)Lu)3(μ(2)-H)3(μ(3)-H)2(CH2SiMe3)(thf)2] and [(Ap*Y)3(μ(2)-H)3(μ(3)-H)2(CH2SiMe3)(thf)2] demonstrated that the trinuclear cores are retained in the solution and revealed exchange between μ(3)- and μ(2)-bridging hydrido ligands. Complexes [(Ap*Ln)3(μ(2)-H)3(μ(3)-H)2(CH2SiMe3)(thf)2], the cationic yttrium hydrido cluster [(Ap*Y)3(μ(2)-H)3(μ(3)-H)2(thf)3](+)[B(C6F5)4](-) as well as [(Ap(9Me)Ln)3(μ(2)-H)3(μ(3)-H)2(CH2SiMe3)(thf)2] proved to be active in catalysis of ethylene polymerization under mild conditions.

Concanavalin A is a legume lectin which preferentially agglutinates transformed cells and shows antitumor effects on human breast carcinoma cells in vitro and in vivo. It is considered as a new potential antineoplastic agent targeting apoptosis, autophagy, and anti-angiogenesis in preclinical or clinical trials for cancer therapeutics, which has recently become the object of intensive study. In the present investigation, we show the capacity of the lectin to bind manganese, gold, iron, and zinc porphyrins: all potential anticancer agents. The interaction of the legume lectin with the studied compounds has been investigated by tryptophan fluorescence, showing conformational changes within the quaternary and tertiary structures of the protein. The binding of Con A with manganese, gold, and iron porphyrins, as well as adenine, was studied by fluorescence quenching. In contrast, the interaction of Con A with zinc porphyrin caused an increase in Trp fluorescence and a red shift of 10 nm of the emission maximum position. However, the binding of Con A to iron porphyrin was accompanied by a 5 nm blue shift of the emission maximum, and a kD of 0.95 ± 0.13 μM was calculated, respectively. The sigmoidal shape of the curve showed cooperative interactions, which indicated the presence of more than one class of binding site within the Con A molecule for iron porphyrin, confirmed by the Hill slope (h = 1.89±0.46). We have found that the legume lectin interacts with porphyrins and adenine with an affinity (0.14-1.89 µM) similar to that of the non-legume lectin, wheat germ agglutinin. In conclusion, the protein Con A shows new binding activity towards porphyrins with anticancer activities and could find prospective application as a drug delivery molecule that specifically targets cancer cells.

Neutral Y(III) dialkyl complexes supported by tridentate N(-) ,N,N monoanionic methylthiazole- or benzothiazole-amidopyridinate ligands have been prepared and completely characterized. Studies on their stability in solution revealed progressive rearrangement of the coordination sphere in the benzothiazole-containing system through an unprecedented metal-to-ligand alkyl migration and subsequent thiazole ring opening. Attempts to synthesize hydrido species from the dialkyl precursor led to the generation of a dimeric yttrium species stabilized by a trianionic N(-) ,N,N(-) ,S(-) ligand as the result of metal-to-ligand hydride migration with chemoselective thiazole ring opening and subsequent dimerization through intermolecular addition of the residual YH group to the imino fragment of a second equivalent of the ring-opened intermediate. DFT calculations were used to elucidate the thermodynamics and kinetics of the process, in support of the experimental evidence. Finally, all isolated yttrium complexes, especially their cationic forms prepared by activation with the Lewis acid Ph3 C(+) [B(C6 F5 )4 ](-) , were found to be good candidate catalysts for intramolecular hydroamination/cyclization reactions. Their catalytic performance with a number of primary and secondary amino alkenes was assessed., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Reaction of bisamidine C6H4-1,2-{NC(t-Bu)NH(2,6-Me2C6H3)}2 (1) and [(Me3Si)2N]2Yb(THF)2 (THF = tetrahydrofuran) (toluene; room temperature) in a 1:1 molar ratio afforded a bis(amidinate) Yb(II) complex [C6H4-1,2-{NC(t-Bu)N(2,6-Me2C6H3)}2]Yb(THF) (2) in 65% yield. Complex 2 features unusual κ(1)amide, η(6)-arene coordination of both amidinate fragments to the ytterbium ion, resulting in the formation of a bent bis(arene) structure. Oxidation of 2 by Ph3SnCl (1:1 molar ratio) or (PhCH2S)2 (1:0.5) leads to the Yb(III) species [C6H4-1,2-{NC(t-Bu)N(2,6-Me2C6H3)}2]YbCl(1,2-dimethoxyethane) (3) and {[C6H4-1,2-{NC(t-Bu)N(2,6-Me2C6H3)}2]Yb(μ-SCH2Ph)}2 (4), performing "classic" κ(2)N,N'-chelating coordination mode of ansa bis(amidinate) ligand. By the reduction of 3 with equimolar amount of sodium naphthalide [C10H8(•-)][Na(+)] in THF, complex 2 can be recovered and restored to a bent bis(arene) structure. Complex 3 was also synthesized by the salt metathesis reaction of equimolar amounts of YbCl3 and the dilithium derivative of 1 in THF.

New heteroleptic Yb(II)-amide species supported by amidinate and 1,3,6,8-tetra-tert-butylcarbazol-9-yl ligands [2-MeOC6H4NC(tBu)N(C6H3-iPr2-2,6)]YbN(SiMe3)2(THF) (6) and [1,3,6,8-tBu4C12H4N]Yb[N(SiMe3)2](THF)n (n = 1 (7), 2 (8)) were synthesized using the amine elimination approach. Complex 6 features an unusual κ(1)-N,κ(2)-O,η(6)-arene coordination mode of the amidinate ligand onto Yb(II). Complexes 7 and 8 represent the first examples of lanthanide complexes with π-coordination of carbazol-9-yl ligands. Complexes 6 and 7, as well as the amidinate-Yb(II)-amide [tBuC(NC6H3-iPr2-2,6)2]YbN(SiMe3)2(THF) (5), are efficient precatalysts for the intermolecular hydrophosphination and hydroamination of styrene with diphenylphosphine, phenylphosphine, and pyrrolidine to give exclusively the anti-Markovnikov monoaddition product. For both types of reaction, the best performances were observed with carbazol-9-yl complex 7 (TONs up to 92 and 48 mol/mol at 60 °C, respectively).

A monoanionic amido-imino ligand system [(2,6-iPr2C6H3)N=C(Me)C(=CH2)N(C6H3-2,6-iPr2)](-) was successfully employed for the synthesis of monomeric dichloro [(2,6-iPr2C6H3)N=C(Me)C(=CH2)N(C6H3-2,6-iPr2)]LnCl2(THF)2 (Ln = Y, 2Y; Lu, 2Lu) and bis(alkyl) [(2,6-iPr2C6H3)N=C(Me)C(=CH2)N(C6H3-2,6-iPr2)]Ln(CH2SiMe3)2(THF) (Ln = Y, 4Y; Lu, 4Lu) species of yttrium and lutetium. Dichloro complexes 2Y and 2Lu turned out to be unstable in aromatic solvents. The ligand symmetrization reaction in the case of 2Y affords the yttrium complex coordinated by dianionic [(2,6-iPr2C6H3)NC(=CH2)C(=CH2)N(C6H3-2,6-iPr2)](2-) ligand, (2,6-iPr2C6H3)N=C(Me)C(Me)=N(C6H3-2,6-iPr2) and YCl3. On the contrary, bis(alkyl) species 4Y and 4Lu are rather stable and do not undergo such a transformation or thermal decomposition. The treatment of complex 4Y with DME resulted in C-O bond cleavage and the formation of a dimeric methoxy-alkyl species {[(2,6-iPr2C6H3)N=C(Me)C(=CH2)N(C6H3-2,6-iPr2)]Y(CH2SiMe3)(μ-OMe)}2 (5). The ternary systems 4Ln/AliBu3/borate (borate = [HNMe2Ph][B(C6F5)4] and [CPh3][B(C6F5)4]; molar ratio 1 : 10 : 1) performed high catalytic activity in isoprene polymerization and ability to convert into polymer 1000-5000 equivalents of isoprene in 20-120 min with quantitative conversion. The obtained polyisoprenes possessed high molecular weights (2.9 × 10(4)-4.1 × 10(4)) and moderate polydispersities (2.14-3.52). Predominant 3,4-regioselectivity (up to 78%) was observed.

Addition of two Ln-H bonds of an Yb(II) hydrido complex supported by bulky amidinate ligand to a C≡C bond lead to the formation of 1,2-dianionic bibenzyl fragment. Both Yb(II) and hydrido centers are oxidized under the reaction conditions. The resulting Yb(II)-η(6) -arene interaction is surprisingly robust: the arene cannot be replaced from the metal coordination sphere when treated with Lewis bases., (Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A steric control on the reductive capacity of ytterbocenes towards iminopyridine ligands is described. The reaction of (η(5)-C(9)H(7))(2)Yb(THF)(2) with 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 Yb(II) metallocene complexes of general formula (η(5)-C(9)H(7))(2)Yb(II)(η(2) or η(3))[2,6-(i)Pr(2)(C(6)H(3))N=CH(C(5)H(3)N)-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.