Despite the well-established importance of chalcogen bonding in crystal engineering and supramolecular chemistry, experimental charge density data for TeII-centered chalcogen bonds have remained entirely absent, leaving the electronic nature of these interactions uncharacterized at the level of directly measured electron density. Here, we report the first high-resolution X-ray diffraction (HRXRD) study of TeII-centered chalcogen bonds, using cocrystals of bis(2,3,5,6-tetrafluoropyridin-4-yl)telluride (Py2FTe) with 1,4-diazabicyclo[2.2.2]octane (DABCO) as a model system; the isostructural S and Se analogues provide a comparative framework across the chalcogen series. Multipole refinement against the HRXRD data yields three findings reported here: direct experimental visualization of the σ-hole on a TeII site via static deformation electron density maps; unambiguous QTAIM-based classification of the TeII···N chalcogen bond as partially covalent (1 < |V|/G < 2) and the TeII···F contact as purely electrostatic (|V|/G < 1); and a quantitative experimental reference for benchmarking DFT methods, with PBE-D3/jorge-DZP-DKH identified as the recommended protocol for heavy-chalcogen σ-hole systems. These results establish a charge density foundation for the rational design of Te-based supramolecular architectures and provide experimental validation of the partially covalent character of TeII-centered chalcogen bonding.

Here, we report the synthesis of tris(benzhydryl) sodium calciate {[(p-tBu-C6H4)2CH]3Ca}Na (3) featuring the structure of a base-free contact ion pair. Catalytic amounts (2 mol%) of 3 containing earth-abundant and biogenic s-metals combined with pyrrolidine as a co-catalyst (H+-donor) enable efficient regio- and stereocontrollable CC bond transposition at ambient temperature. Allyl- and homoallylbenzenes undergo thermodynamically controlled isomerization to afford prop-1-en-1-yl- and but-1-en-1-ylbenzenes with E-stereoselectivity up to 98%. The exceptionally regioselective isomerization of terminal alpha-olefins (1-hexene-1-decene) to internal 2-olefins catalyzed by 3/pyrrolidine (23 degrees C) to yield a mixture of E- and Z-isomers proved to be kinetically controlled. Mechanistic investigations revealed that these processes involve the in situ formation of a heterobimetallic amide complex, which catalyzes olefin isomerization through methylene group deprotonation followed by metallotropic rearrangement. DFT calculations elucidate the mechanism of the catalytic cycle and explain E/Z-selectivity in terms of kinetic and thermodynamic controls. In particular, QTAIM analysis revealed coordination of allylic intermediates to both metallic centers and therefore defined a synergetic effect of the heterobimetallic catalyst.

The reactions of the amino-bis-(3,5-di-tert-butyl-2-hydroxyphenyl) ligand (ON(H)OH2) with one equivalent of Lappert's germylene or stannylene (E[N(SiMe3)2]2, where E = Ge, Sn) afforded the corresponding germylene ON (H)OGe (1) and stannylene ON(H)OSn (2) in satisfactory yields. According to NMR spectroscopic data (1H, 13C, 119Sn, DOSY), compound 2 adopts a dimeric structure in solution. In contrast, X-ray diffraction analysis of 1 reveals a monomeric structure in the solid state, with the tetrel atom having a coordination number of three. The tin compound 2 was further structurally characterized as its hydrazine adduct, [ON(H)OSn]2 & sdot;N2H4 (3). When the ON(H)OH2 ligand was fully deprotonated in the reaction with Lappert's stannylene, a trinuclear complex ONO2Sn3 (4) containing two ligands in trianionic state was obtained. The molecular structures of compounds 1, 3, 4 were determined by single-crystal X-ray diffraction. All synthesized compounds demonstrated high catalytic activity in the hydroboration of benzaldehyde and phenyl isocyanate under ambient conditions, achieving turnover numbers (TON) of up to 1 & times; 104 at a catalyst loading of 0.01 mol%. Probable reaction pathways for the hydroboration of benzaldehyde and phenyl isocyanate, both uncatalyzed and catalyzed, were investigated using density functional theory calculations.

Here, we report the synthesis of tris(benzhydryl) sodium calciate {[(p-tBu-C6H4)2CH]3Ca}Na (3) featuring the structure of a base-free contact ion pair. Catalytic amounts (2 mol%) of 3 containing earth-abundant and biogenic s-metals combined with pyrrolidine as a co-catalyst (H+-donor) enable efficient regio- and stereocontrollable C[double bond, length as m-dash]C bond transposition at ambient temperature. Allyl- and homoallylbenzenes undergo thermodynamically controlled isomerization to afford prop-1-en-1-yl- and but-1-en-1-ylbenzenes with E-stereoselectivity up to 98%. The exceptionally regioselective isomerization of terminal α-olefins (1-hexene-1-decene) to internal 2-olefins catalyzed by 3/pyrrolidine (23 °C) to yield a mixture of E- and Z-isomers proved to be kinetically controlled. Mechanistic investigations revealed that these processes involve the in situ formation of a heterobimetallic amide complex, which catalyzes olefin isomerization through methylene group deprotonation followed by metallotropic rearrangement. DFT calculations elucidate the mechanism of the catalytic cycle and explain E/Z-selectivity in terms of kinetic and thermodynamic controls. In particular, QTAIM analysis revealed coordination of allylic intermediates to both metallic centers and therefore defined a synergetic effect of the heterobimetallic catalyst.

New diorganotin(IV) complexes based on a redox-active tetradentate ONNO ligand, namely N,N'-bis(3,5-di-tert-butyl-2-hydroxyphenyl)-1,2-phenylenediamine (LH4), were synthesized. A methodology for the stepwise oxidation of tin(IV)-ONNO derivatives with a stoichiometric amount of p-benzoquinone was developed. This allowed the preparation of tin(IV) complexes containing the ligand in the tetraanionic doubly deprotonated form, in the dianionic state, and a controlled intraligand cyclization to be carried out. It has been found that the diorganotin(IV) compounds with the dianionic form of the ONNO ligand have a ground singlet spin state, but an increase in temperature leads to partial populating of the triplet state and a transition from the diamagnetic form of these complexes to the paramagnetic biradical ones. The UV-vis-NIR spectrum of L2-SnPh2 shows an intense absorption band in the range of 600-1400 nm, corresponding to the intraligand charge transfer (ILCT). The coordination ability of the solvent strongly influences the position of this solvatochromic band. Cyclic voltammetry revealed that this compound undergoes two sequential reversible single-electron oxidations and two sequential reversible single-electron reductions. This cyclic voltammetry remains unchanged even after 100 cycles have been performed.

During the partial hydrolysis of metal complexes with the mono-imino-acenaphthen-1-olate (R-mian) dianion, the nitrogen atom is protonated at the first stage, while the metal-ligand bond is preserved. Further hydrolysis leads to products whose structure depends on the reaction conditions. Hydrolysis by an excess of water leads to the formation of the products with a reduced C 00000000 00000000 00000000 00000000 11111111 00000000 11111111 00000000 00000000 00000000 N fragment, (amino ketones, R-mianH2). The complexes based on the dianion of (E)-2-(2,6-diisopropylphenylimino)acenaphthylen-1(2H)-one (dpp-mian) are hydrolyzed by a HBF4 aqueous solution to give an ammonium salt containing a reduced CN fragment with the proton bound to the ammonium nitrogen atom [(dpp-mainH3)1+BF4]. When these compounds interact with an aqueous solution of HCl, the carbonyl group CO is involved, while the acid proton coordinates to the nitrogen atom [(dpp-mainH3)1+Cl]. MP2 calculations explain the formation of different products. Hydrolysis of the metal complexes, bearing a R-mian radical-anion, by water produces a stoichiometric mixture of R-mianH2 and R-mian as a result of the R-mianH disproportionation. The reaction of R-mian with lithium aluminum hydride leads to the reduction of both the CN and CO fragments.

We studied the reactions of sterically hindered bis-semiquinonates of copper(II) with 4,4′-bipyridine. Coordination polymer consisting of metallamacrocyclic binuclear copper(II) cage-like moieties bridged with 4,4′-bipyridine linkers was isolated in the reaction of copper(II) bis-semiquinonate metallamacrocycle with 4,4′-bipyridine. It is important that the initial and final metallamacrocycles in this reaction are different by the disposition of semiquinone units in the coordination surroundings of copper (II) ions. The transformation of one metallamacrocycle into another could only be achieved by a two-fold sequential cleavage of the metal-semiquinone bond.

The dichlorido titanium(IV) complex [(tmp-BIAN)TiCl2]2 (2) supported by formally dianionic tmp-BIAN (=1,2bis[(2,4,6-trimethylphenyl)imino]acenaphthene) was obtained via the reduction of [(tmp-BIAN)TiCl4] (1) with alkali metal. According to the EPR data, the target compound exhibits Ti-centered temperature-independent paramagnetism in the solid state. Meanwhile, the XRD analysis verifies the enebisamide form of the N-ligand in 2. An exchange of the chlorides into the double reduced tmp-BIAN ligand, along with a two-electron oxidation of complex 2 with trimethylsilyl azide, leads to the formation of diamagnetic species (3 and 4, respectively). The spectral and structural data obtained confirm compounds 3 and 4 as titanium d0 complexes.

Trifluoroacetamide CF3C(O)NH2, N,N'-bis(trifluoroacetyl)ethylenediamine CF3C(O)NHCH2CH2HN(O)CCF3, trifluoroacetyl-2-aminoethanol CF3C(O)NHCH2CH2ОН, and 1,2-bis(trifluoroacetylaminoethoxy)ethane CF3C(O)NHCH2CH2ОCH2CH2ОCH2CH2НN(O)CCF3 were synthesized by the thermal decomposition (200–250°С, Ar) of the corresponding ammonium and aminium salts, such as ammonium trifluoroacetate CF3C(O)O‒ +NH4, N,N'-ethylenediamine bis(trifluoroacetate) CF3COO‒ +NH3CH2CH2H3N+ ‒OOCCF3, 2-aminoethanol trifluoroacetate CF3COO‒ +NH3CH2CH2ОН, and 1,2-bis(aminoethoxy)ethane bis(2-trifluoroacetate) CF3COO‒ +NH3CH2CH2ОCH2CH2ОCH2CH2Н3N+ ‒OOCCF3. The synthesized compounds were characterized by elemental analysis, powder X-ay diffraction, IR and NMR spectroscopy, mass spectrometry, thermogravimetry, optical and scanning electron microscopy. The molecular structure of ethylenediamine N,N'-bis(trifluoroacetate) was determined.

Monoethanolaminium trifluoroacetate (HO‒CH2CH2‒NH _3^ + ‒O(O)C‒CF3), triethanolaminium trifluoroacetate ((HO‒CH2CH2)3NH+ ‒O(O)C‒CF3), tris(hydroxymethyl)methanaminium trifluoroacetate ((HO‒CH2)3C-NH _3^ + ‒O(O)C‒CF3), and 2,2'-(ethylenedioxy)di(ethylaminium) bis(trifluoroacetate) (CF3-C(O)O‒ +H3N-(CH2CH2O)2CH2CH2-NH _3^ + ‒O(O)C‒CF3) were synthesized by the reactions of trifluoroacetic acid with monoethanolamine, triethanolamine, tris(hydroxymethyl)methanamine, and 2,2'-(ethylenedioxy)di(ethylamine), respectively. Ammonium trifluoroacetate (NH _4^ + ‒OC(O)CF3) was prepared by the reaction of trifluoroacetic acid with hexamethyldisilazane and with trimethylsilyl trifluoroacetate CF3C(O)OSi(CH3)3. The synthesized compounds are low-melting crystalline salts, which are transferred into a vapor phase upon heating to 200–220°С. The reaction of CF3C(O)OSi(CH3)3 with monoethanolamine afforded monoethanolaminium trifluoroacetate instead of expected 2,2,2-trifluoro-N-(2-hydroxyethyl)acetamide CF3C(O)-NH-CH2CH2OH. The aminium salts were characterized by IR and NMR spectroscopy, mass spectrometry, high-performance liquid chromatography, and scanning electron microscopy. The thermal behavior and thermal stability of the salts were studied by differential scanning calorimetry and thermogravimetry, respectively. The molecular structures of monoethanolaminium trifluoroacetate, triethanolaminium trifluoroacetate, tris(hydroxymethyl)methanaminium trifluoroacetate, and ammonium trifluoroacetate were determined.

In this work, an approach enabling the synthesis of η2-alkene lithium complexes (Carb2,4,6-iPr)Li(η2-L) (L = 1-octene, cyclohexene) is elaborated. For 1,5-hexadiene, the same approach results in a binuclear μ-η2:η2-diene complex. The QTAIM parameters reveal the electrostatic nature of the Li-alkene interaction. When treated with cyclohexane, alkene ligands in (Carb2,4,6-iPr)Li(η2-L) are readily replaced to afford the Li-alkane complex (Carb2,4,6-iPr)Li(κ2-C6H12) featuring anagostic Li···H interactions. The reverse reaction readily proceeds in the presence of excess alkene. The QTAIM and LED analyses performed at the DLPNO-CCSD(T) level show a small difference between the complexes in the total dispersion contribution (16.0-18.5 kcal/mol) and interaction energy for Li-alkene (∼3.5 kcal/mol) or Li-C6H12 (∼4 kcal/mol). These values suggest the presence of an equilibrium between these entities, which can be readily shifted by the presence of an excess of alkene or alkane. (Carb2,4,6-iPr)Li(η2-L) and (Carb2,4,6-iPr)Li(κ2-C6H12) are transformed into η2-arene complexes upon treatment with benzene; however, a reverse reaction is not possible at room temperature.

Ditopic ligand containing two 3,6-di-tert-butyl-o-benzoquinonato fragments linked through 4-position by resorcinol bridge was utilized for synthesis of metallamacrocyclic complexes with tellurium and nickel. Both compounds consist of two metal-centered coordination units connected by two bis-dioxolenes. Coordination units have distorted octahedral geometry. Four coordinated oxygen atoms of dioxolenes form uncompleted distorted octahedron environment. The lacking sites in octahedron coordination sphere are filled with electronic lone pairs in the case of tellurium and phenanthroline ligand in the case of nickel. In contrast to previously described cobalt and nickel complexes with the same bis-dioxolene, metal units are situated not cofacially. The reason of this is saturation of coordination sphere of central atom until octahedron which excludes coordination with internal solvent molecule which can connect both metals.

Six new coordination polymers (CPs) of cadmium based on an extended anilate-type ligand, 4,4 '-(1,4-phenylenebis(azanylylidene))bis(3,6-di-tert-butyl-2-hydroxycyclohexa-2,5-dienone) (H2L), have been synthesized. The series of coordination polymers includes [Cd(L)(DMF)] (1), 1D-CP [Cd(L)(dipy-1)]2DMF (2A) and 2D-CP [Cd(L)(dipy-1)]DMF (2B), [Cd2(L)2(dipy-2)(DMF)2] (3), [Cd(HL)(CH3COO)(dabco)] (4) and [Cd(L)(ur)2](H2L) (5) (where L - deprotonated form of H2L, DMF - N,N '-dimethylformamide, dipy-1 - 4,4 '-trimethylenedipyridine, dipy-2 - 4,4 '-dipyridyl, dabco - 1,4-diazabicyclo[2.2.2]octane, ur - urotropine). The crystal structure and thermal decomposition of 1D- and 2D-coordination polymers are reported. The structural diversity of the synthesized compounds was found to depend on the additional neutral donor ligands in the cadmium coordination sphere. Thus, the introduction of the flexible N-donor ligand dipy-1 into the cadmium coordination sphere leads to the formation of two types of coordination polymers (1D and 2D). The use of the rigid ligand dipy-2 promotes the formation of "honeycomb" 2D-CPs. The use of shorter N-donor ligands dabco and ur leads to linear derivatives in which the ligands being coordinated by cadmium don't act as "crosslinkers" of the chains in the network. The extended anilate ligand is an excellent platform for designing MOFs with diverse structures and topologies.

The study of a binuclear copper complex, bearing a cage-like architecture, and obtained by self-assembly from a ditopic di-o-quinone ligand containing bulky substituents in the linker, showed that the exchange interactions characteristic of biradical forms of the free ligand are fully manifested in the obtained complex. The energy of the exchange interactions changes depending on the volume of the substituents that limit rotational vibrations around the linker bonds.

The reaction of [Sc(CH2SiMe3)3(THF)2] with an equimolar amount of 1,3-bis(2,4,6-trimethylphenyl)-3,4,5,6-tetrahydropyrimidinium chloride in toluene proceeds with a deprotonation of the latter and activation of a CH-bond of one of methyl groups in the ortho-position of the 2,4,6-trimethylphenyl substituent to form an alkyl complex [κ2-C-(2,4,6-Me3C6H2)N(CH2)3N-4,6-Me2C6H2-2-CH2-κ1]Sc(μ2-Cl)CH2SiMe32 coordinated by a κ1C:κ2C-bonded expanded-ring NHC-ligand.

Multistability on the molecular scale level required for molecular devices can be realized using metallocomplexes with redox-active ligands such as o-quinones, o-quinoneimines and o-diimines as building blocks. Herein, we prepared four sterically shielded di-o-quinones bridged with a dioxyarylene linker with different topology and steric characteristics and studied the properties of their reduced species. EPR spectroscopy investigation revealed that the intramolecular exchange interaction between paramagnetic centers in the biradical dianion derivatives of synthesized di-o-quinones predominantly depends on the steric environment of the linker and the nature of the counter cation at the dioxolene site, and the topology of the linker plays a secondary role.

Reaction of 3-hydroxy-2,5-di-tert-butyl-1,4-benzoquinone tert-butyl-1,4-benzoquinone with phenylhydrazine hydrochloride mainly leads to the corresponding hydrazone at the position 1 existing in tautomeric equilibrium with 3,6-di-tert-butyl-4-(phenyl- tert-butyl-4-(phenyl- diazenyl)catechol. Thermodynamic parameters of the tautomerization were evaluated by NMR spectroscopy. The hydrazone structure was confirmed by XRD study.

Copper(II) complexes on the basis of 3,5-di-tert-octyl-o-benzoquinone (3,5-tOc-Q) have been synthesised. Derivatives of the composition: (3,5-tOc-SQ)2Cu (I), (3,5-tOc-Cat)Cu(Phen) (II), (3,5-tOc-Cat)Cu(DPQ) (III) and (3,5-tOc-Cat)Cu(DPPZ) (IV), where 3,5-tOc-SQ is the anion radical of 3,5-di-tert-octyl-o-benzoquinone, 3,5-tOc-Cat is the dianion of 3,5-di-tert-octyl-o-benzoquinone, Phen is phenanthroline, DPQ is dipyrido[3,2-d: 2′,3′-f]quinoxaline, DPPZ — dipyrido[3,2-a:2′,3′-c]phenazine. The molecular and crystal structures of complexes I and II were established by X-ray diffraction. The spectral characteristics of the synthesised copper(II) derivatives have been investigated by electronic absorption spectroscopy. Crystallographic data for compounds I and II have been deposited in the Cambridge Structural Data Bank (No. 2291614 for I and No. 2279045 for II).

Recently obtained bis-o-quinone with resorcinol as a bridge was utilized for synthesis of cobalt and nickel homobinuclear complexes. Two bis-o-semiquinonato metal fragments are situated co-facially to each other forming metallomacrocycle. Metals in both fragments bond diethyl ether solvate molecules externally as well as internally in the cell. At 100 K one of two metal atoms in the macrocycle is five-coordinated whereas the other one is six-coordinated due to internal solvent molecule. Heating to room temperature results in disordering of internal solvent molecule in two positions: coordinated to different nickel atoms. Variable temperature magnetic measurements indicate both complexes to be bis-o-semiquinonato anion-radical adducts of high spin metals with magnetic interactions inside of bis-o-semiquinonato units. Sign and energy of interactions depend on the coordination number of metal. Exchange interactions between units are weak. UV-Vis absorption spectrum is determined by ligands centered bands. CV indicates reversible reduction processes involving redox active dioxolene ligands.

Deprotonation of 5-methyl-5,6-dihydroindeno[2,1-b]indole (L 1 H) or 2-(tert-butyl)-5-methyl-5,6-dihydroindeno[2,1-b]indole (L 2 H) with an equimolar amount of n-BuLi in Et2O affords the 5,6-dihydroindeno[2,1-b]indolyl derivatives L 1 Li(Et2O)2 (1) and [L 2 Li(Et2O)]6 (2) in 67 and 73% yields. Complex 1 proved to be monomeric in the crystalline state, whereas 2 adopts a cyclic hexameric structure. The protonation of Sc(CH2C6H4-o-NMe2)3 by an equimolar amount of [HNEt3][BPh4] allows for the synthesis of a cationic scandium bis(o-aminobenzyl) complex [Sc(CH2C6H4-o-NMe2)2(THF)2][BPh4] (3) which was successfully employed as a precursor for the preparation of bis(o-aminobenzyl) 5,6-dihydroindeno[2,1-b]indolyl species. The salt metathesis reactions of lithium derivatives 1 and 2 with 3 (THF, 20 degrees C) afford complexes L 1 Sc(CH2C6H4-o-NMe2)2 (4) and L 2 Sc(CH2C6H4-o-NMe2)2 (5) in 69 and 73% yields. Complexes 4 and 5 are monomeric and Lewis-base free. Complexes 4 and 5 as part of binary (4, 5/[Ph3C][B(C6F5)4], 4, 5/[PhNHMe][B(C6F5)4]) and ternary (4, 5/([Ph3C][B(C6F5)4], [PhNHMe][B(C6F5)4])/AliBu3 (1:1:10)) catalytic systems are efficient initiators for isoprene polymerization which enable quantitative conversion of monomers in 30 min ([IP]/[Ln] = 1000) even at -30 degrees C. The resulting polymers have a predominantly cis-1,4 structure (up to 80.9%; M n = 58.8-2315.9 x 103; M w/M n = 1.35-3.12). Complexes 4 and 5 catalyze the intermolecular hydrophosphination of styrene, alpha-methylstyrene, and phenylacetylene with Ph2PH and PhPH2 under mild conditions.