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Self-assembly synthesis of mixed-ligand (silsesquioxane/acetate) complex allows to isolate record high nuclear copper(II) Cu13-cage (1). In the presence of two additional sodium ions, a unique molecular architecture, with triple combination of ligands (cyclic and acyclic silsesquioxanes as well as acetates), has been formed. The structure was established by single-crystal X-ray diffraction based on the use of synchrotron radiation. Complex 1 was evaluated as precatalyst in the Baeyer-Villiger oxidation of cyclohexanone towards ε-caprolactone, employing hydrogen peroxide, tert-butyl hydroperoxide (TBHP) or m-chloroperoxybenzoic acid (mCPBA) as oxidants, in an aqueous acidic acetonitrile medium. The direct formation of the lactone from cyclohexane via a tandem peroxidative oxidation/Baeyer-Villiger oxidation was also studied. For both substrates, the best results (ε-caprolactone yields up to 100% or 26%, from cyclohexanone or cyclohexane, respectively) were achieved with mCPBA under considerably mild conditions, i.e., conventional heating at 50 °C for 4 h or microwave (MW) irradiation at 80 °C for only 30 minutes., (© 2024 Wiley‐VCH GmbH.)

The first metallasilsesquioxane bearing pyrazolylpyridine ligands, the Cu 8 -based complex 1, adopts a cage-like structure with two zigzag-type copper tetramers sandwiched by two cyclic Si 5 silsesquioxane ligands. The four 3-phenyl-5-(2-pyridyl)pyrazolate ligands in 1 exhibit dual (chelating and bridging) modes of ligation. Compound 1 is very active in the oxidation of alkanes and alcohols.

Octahedral Mn(I) complexes bearing tridentate donor ligands [(L ∩ L' ∩ L'')(CO) 2 MnX] have recently emerged as major players in catalytic (de)hydrogenation processes. While most of these systems are still based on structurally rigid pincer scaffolds imposing a meridional coordination mode, for some more flexible tridentate ligands a facial arrangement of donor moieties becomes possible. Accordingly, the geometry of the corresponding Mn(I) hydrides [(L ∩ L' ∩ L'')(CO) 2 MnH] directly involved in the catalytic processes, namely the nature of the donor extremity located in the trans -position of the hydride (CO and L for mer - and fac -configurations, respectively) may influence their hydride transfer ability. Herein, low-temperature IR and NMR spectroscopy studies of two model Mn(I) complexes, mer -[(L1)(CO) 2 MnH] and fac -[(L2)(CO) 2 MnH], bearing similar triphosphine ligands (L1 = PhP(CH 2 CH 2 PPh 2 ) 2 ; L2 = MeC(CH 2 PPh 2 ) 3 ) in the presence of B(C 6 F 5 ) 3 as the H - abstractor revealed for the first time a higher kinetic hydricity of the tripodal system. Even for the pincer complex, hydride transfer proceeds from the non-covalent adduct fac -[(L1)(CO) 2 MnH]⋯B(C 6 F 5 ) 3 with the facial geometry arising from the mer -to- fac isomerization of the initial mer -[(L1)(CO) 2 MnH]. The higher reactivity of the fac -hydride derivatives was found to be consistent with the catalytic performance of the corresponding Mn(I) bromide complexes in the benchmark ester hydrosilylation.

We report a high nuclear (Cu 14 ) complex synthesized via the self-assembly of copper-methylsilsesquioxane induced by the complexation with 1,2-bis(diphenylphosphino)ethane (dppe). The structure includes two cationic Cu I (dppe) 2 moieties and an anionic silsesquioxane cage of an unprecedented Cu II 12 structural type. The Cu 12 cage fragment exhibits a unique ( i ) combination of Si 4 -cyclic/Si 2 -acyclic silsesquioxane ligands and ( ii ) encapsulation of two different chloride and carbonate species. This complex acts as a promising precatalyst in the mild oxidation and carboxylation of light alkanes to produce alkyl hydroperoxides, alcohols, ketones, or carboxylic acids. The present study widens the family of copper-methylsilsesquioxane clusters with prospective use in oxidation catalysis.

The synthesis of a high nuclear (Cu 9 Na 4 ) complex 1 via the self-assembly of copper(II) phenylsilsesquioxane induced by complexation with bis(triphenylphosphine)iminium chloride (PPNCl) was successfully achieved. This complex, which includes two bis(triphenylphosphine)iminium PPN + cations, represents the first example of a metallasilsesquioxane/phosphazene compound. The Cu 9 Na 4 -silsesquioxane cage demonstrates a nontrivial combination of two pairs of Si 6 -cyclic/Si 4 -acyclic silsesquioxane ligands and a fusion of two Si 10 Cu 4 Na 2 fragments, combined via the central ninth copper ion. The catalytic efficacy of the copper(II) compound (1) was evaluated through the peroxidative oxidation of toluene using tert -butyl hydroperoxide ( t -BuOOH) as the oxidant. The primary oxidation products were benzaldehyde (BAL), benzyl alcohol (BOL), and benzoic acid (BAC), with BAC being the predominant product, especially in acetonitrile (NCMe). The formation of cresols, indicating oxidation at the aromatic ring, was observed only in water and under microwave irradiation (MW) in NCMe. Remarkably, the highest total yield of 40.3% was achieved in water with an acidic additive at 80 °C, highlighting the crucial role of the acid additive in enhancing reaction efficiency and selectivity. This study underscores our copper(II) complex as a highly effective catalyst for toluene oxidation, demonstrating its significant potential for fine-tuning reaction parameters to optimize yields and selectivity. The unprecedented structure of the complex and its promising catalytic performance pave the way for further advancements in the fields of metallasilsesquioxane chemistry and catalysis.

An extended ( i.e. , 19 distinct species) family of cage-like Cu 4 -phenylsilsesquioxanes allowed us to accentuate the general regularities behind their structural organization. Influencing factors, namely the (i) size of external alkali metal ions (from Li to Cs) and (ii) nature of bridging linkers (including the smallest possible ones, like a water molecule) on the self-assembly/supramolecular assembly of such Cu 4 -building blocks have been thoroughly explored. A Cu 4 K 4 -based complex has been evaluated as a precatalyst in the oxidation of alkanes (cyclohexane, n -heptane, methylcyclohexane) and alcohols. The experimental evidence that radical species participate in the oxidation of alkanes is provided.

A series of structurally similar trinuclear macrocyclic copper(I) and silver(I) pyrazolate complexes bearing various short-bite diphosphine R 2 PCH(R')PR 2 ligands are reported. Upon diphosphine coordination, the planar geometry of the initial complexes undergoes bending along the line between two metal atoms coordinated to the phosphorus moieties. The complexes based on dcpm ligands (R = cyclohexyl, R' = H, Ph) do not exhibit dynamic behavior in solution at room temperature on the 31 P NMR time scale as it was previously observed for similar trinuclear copper complexes bearing the dppm (R = Ph, R' = H) scaffold. All copper(I) complexes exhibit thermally activated delayed fluorescence (TADF) behavior in the solid state. Importantly, the use of aliphatic substituents on the phosphorus atoms instead of aromatic ones leads to an almost double increase in the quantum efficiency (Φ PL ) of photoluminescence by eliminating nonradiative decay from the 3 LC Ph states of the dppm aromatic rings. The higher donating ability of the substituents in the pyrazolate ligand (CF 3 vs CH 3 ) lowers the energy of the metal-centered excited state, allowing for a significant metal impact on the T 1 state. Finally, the Ag(I) complex displays an emission efficiency of approximately 14%, being the highest among known trinuclear silver(I) pyrazolate homometallic derivatives.

Despite the significance of H 2 O 2 -metal adducts in catalysis, materials science and biotechnology, the nature of the interactions between H 2 O 2 and metal cations remains elusive and debatable. This is primarily due to the extremely weak coordinating ability of H 2 O 2 , which poses challenges in characterizing and understanding the specific nature of these interactions. Herein, we present an approach to obtain H 2 O 2 -metal complexes that employs neat H 2 O 2 as both solvent and ligand. SnCl 4 effectively binds H 2 O 2 , forming a SnCl 4 (H 2 O 2 ) 2 complex, as confirmed by 119 Sn and 17 O NMR spectroscopy. Crystalline adducts, SnCl 4 (H 2 O 2 ) 2 ·H 2 O 2 ·18-crown-6 and 2[SnCl 4 (H 2 O 2 )(H 2 O)]·18-crown-6, are isolated and characterized by X-ray diffraction, providing the complete characterization of the hydrogen bonding of H 2 O 2 ligands including geometric parameters and energy values. DFT analysis reveals the synergy between a coordinative bond of H 2 O 2 with metal cation and its hydrogen bonding with a second coordination sphere. This synergism of primary and secondary interactions might be a key to understanding H 2 O 2 reactivity in biological systems., (© 2024. Crown.)

Convenient self-assembly synthesis of copper(II) complexes via double (phenylsilsesquioxane and acetate) ligation allows to isolate a family of impressive sandwich-like cage compounds. An intriguing feature of these complexes is the difference in the structure of a pair of silsesquioxane ligands despite identical (Cu 6 ) nuclearity and number (four) of acetate fragments. Formation of particular combination of silsesquioxane ligands (cyclic/cyclic vs condensed/condensed vs cyclic/condensed) was found to be dependent on the synthesis/crystallization media. A combination of Si 4 -cyclic and Si 6 -condensed silsesquioxane ligands is a brand new feature of cage metallasilsesquioxanes. A representative Cu 6 -complex (4) (with cyclic silsesquioxanes) exhibited high catalytic activity in the oxidation of alkanes and alcohols with peroxides. Maximum yield of the products of cyclohexane oxidation attained 30 %. The compound 4 was also tested as catalyst in the Baeyer-Villiger oxidation of cyclohexanone by m-chloroperoxybenzoic acid: maximum yields of 88 % and 100 % of ϵ-caprolactone were achieved upon conventional heating at 50 °C for 4 h and MW irradiation at 70 or 80 °C during 30 min, respectively. It was also possible to obtain the lactone (up to 16 % yield) directly from the cyclohexane via a tandem oxidation/Baeyer-Villiger oxidation reaction using the same oxidant., (© 2024 Wiley-VCH GmbH.)

We report the synthesis and single-crystal X-ray diffraction, magnetic, and luminescence measurements of a novel family of luminescent cage-like tetranuclear silsesquioxanes (PhSiO 1.5 ) 8 (LnO 1.5 ) 4 (O)(C 5 H 8 O 2 ) 6 (EtOH) 2 (CH 3 CN) 2 ⋅2CH 3 CN (where Ln = Tb, 1 ; Tb/Eu, 2 ; and Gd, 3 ), featuring seven-coordinated lanthanide ions arranged in a one-capped trigonal prism geometry. Compounds 1 and 2 exhibit characteristic Tb 3+ and Tb 3+ /Eu 3+ -related emissions, respectively, sensitized by the chelating antenna acetylacetonate (acac) ligands upon excitation in the UV and visible spectral regions. Compound 3 is used to assess the energies of the triplet states of the acac ligand. For compound 1 , theoretical calculations on the intramolecular energy transfer and multiphonon rates indicate a thermal balance between the 5 D 4 Stark components, while the mixed Tb 3+ /Eu 3+ analog 2 , with a Tb:Eu ratio of 3:1, showcases intra-cluster Tb 3+ -to-Eu 3+ energy transfer, calculated theoretically as a function of temperature. By utilizing the intensity ratio between the 5 D 4 → 7 F 5 (Tb 3+ ) and 5 D 0 → 7 F 2 (Eu 3+ ) transitions in the range 11-373 K, we demonstrate the realization of a ratiometric luminescent thermometer with compound 2 , operating in the range 11-373 K with a maximum relative sensitivity of 2.0% K -1 at 373 K. These findings highlight the potential of cage-like silsesquioxanes as versatile materials for optical sensing-enabled applications., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The author(s) declared that they were an editorial board member of Frontiers, at the time of submission. This had no impact on the peer review process and the final decision., (Copyright © 2024 Félix, Kulakova, Sene, Khrustalev, Hernández-Rodríguez, Shubina, Pelluau, Carlos, Guari, Carneiro Neto, Bilyachenko and Larionova.)

Unprecedented iron-based silsesquioxane/acetylacetonate complexes were synthesized. The intriguing cage-like structure of compounds is alkaline metal-dependent: the Fe 2 Li 2 complex includes condensed Si 6 -silsesquioxane and four acetylacetonate ligands; the Fe 4 Na 4 complex exhibits two cyclic Si 4 -silsesquioxane and eight acetylacetonate ligands, while the Fe 3 K 3 complex features two cyclic Si 3 -silsesquioxane and six acetylacetonate ligands. The latter case is the very first observation of small trimeric silsesquioxane ligands in the composition of cage-like metallasilsesquioxanes. The Fe 4 Na 4 -based complex exhibits a record high activity in the oxidation of inert alkanes with peroxides (55% yield of oxygenates in cyclohexane oxidation). It also acts as a catalyst in the cycloaddition of CO 2 with epoxides, leading to cyclic carbonates in good yields (58-96%).

Cyclic trinuclear Ag(I) pyrazolate interacts with phenylacetylene forming a mix-ligand complex in which one pyrazolate ligand is changed to phenylethynide. The CC - fragment coordinates only to two silver(I) atoms via one carbon atom demonstrating unique μ 2 -η 1 σ-coordination with close Ag-C bond lengths and Ag-C-C angles. The complex exhibits blue emission under UV irradiation.

Metal-metal cooperation for inert bond activation is a ubiquitous concept in coordination chemistry and catalysis. While the great majority of such transformations proceed via intramolecular mode in binuclear complexes, to date only a few examples of intermolecular small molecule activation using usually bimetallic frustrated Lewis pairs (M δ + ⋯M' δ - ) have been reported. We introduce herein an alternative approach for the intermolecular bimetallic cooperativity observed in the catalytic dehydrogenation of amine-boranes, in which the concomitant activation of N-H and B-H bonds of the substrate via the synergetic action of Lewis acidic (M + ) and basic hydride (M-H) metal species derived from the same mononuclear complex (M-Br). It was also demonstrated that this system generated in situ from the air-stable Mn(i) complex fac -[(CO) 3 (bis(NHC))MnBr] and NaBPh 4 shows high activity for H 2 production from several substrates (Me 2 NHBH 3 , t BuNH 2 BH 3 , MeNH 2 BH 3 , NH 3 BH 3 ) at low catalyst loading (0.1% to 50 ppm), providing outstanding efficiency for Me 2 NHBH 3 (TON up to 18 200) that is largely superior to all known 3d-, s-, p-, f-block metal derivatives and frustrated Lewis pairs (FLPs). These results represent a step forward towards more extensive use of intermolecular bimetallic cooperation concepts in modern homogeneous catalysis., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

This study reports a novel family of cage manganesesilsesquioxanes prepared via complexation with bathophenanthroline (4,7-diphenyl-1,10-phenanthroline). The resulting Mn 4 -, Mn 6 Li 2 -, and Mn 4 Na-compounds exhibit several unprecedented cage metallasilsesquioxane structural features, including intriguing self-assembly of silsesquioxane ligands. Complexes were tested in vitro for fungicidal activity against seven classes of phytopathogenic fungi. The representative Mn 4 Na-complex acts as a catalyst in the cycloaddition of CO 2 to epoxides under solvent-free conditions to form cyclic carbonates in good yields.

Lanthanide-based silsesquioxanes constitute an emerging family of cage-like metallasilsesquioxanes with exciting optical and magnetic properties. We report here the synthesis, structures and luminescence properties of a series of tetranuclear lanthanide-silsesquioxane compounds of general formula [NEt 4 ] 2 [(Ph 4 Si 4 O 8 ) 2 (Ln/Ln') 4 (NO 3 ) 6 (EtOH) 2 (MeCN) 2 ]·4(MeCN) with different lanthanide ions (where Ln/Ln' = Dy 3+ /Eu 3+ (1), Dy 3+ /Tb 3+ (2) and Eu 3+ /Tb 3+ /Y 3+ (3)) and investigate the impact of the lanthanide ions combination on magnetic and photo-luminescent properties. Compound 1 behaves as a field-induced Single Molecule Magnet (SMM) and presents temperature-dependent luminescence characteristics of Eu 3+ making it an emissive thermometer working in the temperature range 293-373 K with the maximum relative sensitivity of 1.15% K -1 achieved at 293 K. Compounds 2 and 3 are paramagnets, which demonstrate a characteristic photoluminescence with Dy 3+ to Tb 3+ and Tb 3+ to Eu 3+ energy transfers, respectively., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

A small family of nonanuclear Cu 5 Cs 4 -based phenylsilsesquioxanes 1 - 2 were prepared by a convenient self-assembly approach and characterized by X-ray diffraction studies. The compounds 1 and 2 show some unprecedented structural features such as the presence of a [Ph 14 Si 14 O 28 ] 14- silsesquioxane ligand and a Cu II 5 Cs I 4 nuclearity in which the metal cations occupy unusual positions within the cluster. Copper ions are "wrapped" into a silsesquioxane matrix, while cesium ions are located in external positions. This resulted in cesium-involved aggregation of coordination polymer structures. Both compounds 1 and 2 realize specific metallocene (cesium-phenyl) linkage between neighboring cages. Compound 2 is evaluated as a catalyst in the Baeyer-Villiger (B-V) oxidation of cyclohexanone and tandem cyclohexane oxidation/B-V oxidation of cyclohexanone with m -chloroperoxybenzoic acid (mCPBA) as an oxidant, in an aqueous acetonitrile medium, and HNO 3 as the promoter. A quantitative yield of ε-caprolactone was achieved under conventional heating at 50 °C for 4 h or MW irradiation for 30 min (for cyclohexanone as substrate); 17 and 19% yields of lactone upon MW irradiation at 80 °C for 30 min and heating at 50 °C for 4 h, respectively (for cyclohexane as a substrate), were achieved. Complex 2 was evaluated as a catalyst for the oxidation of alkanes to alkyl hydroperoxides and alcohols to ketones with peroxides at 60 °C in acetonitrile. The maximum yield of cyclohexane oxidation products was 30%. Complex 2 exhibits high activity in the oxidation of alcohols.

Acid-base characteristics (acidity, p K a, and hydricity, ΔG° H- or k H- ) of metal hydride complexes could be a helpful value for forecasting their activity in various catalytic reactions. Polarity of the M-H bond may change radically at the stage of formation of a non-covalent adduct with an acidic/basic partner. This stage is responsible for subsequent hydrogen ion (hydride or proton) transfer. Here, the reaction of tricarbonyl manganese hydrides mer , trans -[L 2 Mn(CO) 3 H] ( 1 ; L = P(OPh) 3 , 2 ; L = PPh 3 ) and fac -[(L-L')Mn(CO) 3 H] ( 3 , L-L' = Ph 2 PCH 2 PPh 2 (dppm); 4 , L-L' = Ph 2 PCH 2 -NHC) with organic bases and Lewis acid (B(C 6 F 5 ) 3 ) was explored by spectroscopic (IR, NMR) methods to find the conditions for the Mn-H bond repolarization. Complex 1 , bearing phosphite ligands, features acidic properties (p K a 21.3) but can serve also as a hydride donor (ΔG ≠ 298K = 19.8 kcal/mol). Complex 3 with pronounced hydride character can be deprotonated with KHMDS at the CH 2 -bridge position in THF and at the Mn-H position in MeCN. The kinetic hydricity of manganese complexes 1 - 4 increases in the order mer , trans -[(P(OPh) 3 ) 2 Mn(CO) 3 H] ( 1 ) < mer , trans -[(PPh 3 ) 2 Mn(CO) 3 H] ( 2 ) ≈ fac -[(dppm)Mn(CO) 3 H] ( 3 ) < fac -[(Ph 2 PCH 2 NHC)Mn(CO) 3 H] ( 4 ), corresponding to the gain of the phosphorus ligand electron-donor properties.

A family of unusual octacopper cage methylsilsesquioxanes 1 - 4 were prepared and characterized. Features of their cagelike (prismatic) structure were established using X-ray diffraction studies. Effects of distortion of prismatic cages 1 - 4 due to variation of (i) additional alkaline metal ions (K, Rb, or Cs), (ii) combination of solvating ligands, and (iii) nature of encapsulating species were found. Opportunities for the design of supramolecular 1D extended structures were found. These opportunities are based on (i) formate linkers between copper centers (in the case of Cu 8 K 2 -based compound 2 ) or (ii) crown ether-like contacts between cesium ions and siloxane cycles (in the case of Cu 8 Cs 2 -based compound 4 ). Cu 8 Cs 2 -complex 4 was evaluated in the catalysis of alkanes and alcohols. Complex 4 exhibits high catalytic activity. The yield of cyclohexane oxidation products is 35%. The presence of nitric acid is necessary as a co-catalyst. The oxidation of alcohols with the participation of complex 4 as a catalyst and tert-butyl hydroperoxide as an oxidizer also proceeds in high yields of up to 98%.

A reaction of a cyclic trinuclear copper(I) or silver(I) pyrazolate complex ([MPz] 3 , M = Cu, Ag) with 1,1'-dimethyl-2,2'-bibenzimidazole ( L ) leads to the formation of tetranuclear adducts decorated by one or two molecules of a diimine ligand, depending on the amount of the ligand added (0.75 or 1.5 equivalents). The coordination of two L molecules stabilizes the formation of a practically idealized tetrahedral four-metal core in the case of a copper-containing complex and a distorted tetrahedron in the case of a Ag analog. In contrast, complexes containing one molecule of diimine possess two types of metals, two- and three-coordinated, forming the significantly distorted central M 4 cores. The diimine ligands are twisted in these complexes with dihedral angles of ca. 50-60°. A TD-DFT analysis demonstrated the preference of a triplet state for the twisted 1,1'-dimethyl-2,2'-bibenzimidazole and a singlet state for the planar geometry. All obtained complexes demonstrated, in a solution, the blue fluorescence of the ligand-centered (LC) nature typical for free diimine. In contrast, a temperature decrease to 77 K stabilized the structure close to that observed in the solid state and activated the triplet states, leading to green phosphorescence at ca. 500 nm. The silver-containing complex Ag 4 Pz 4 L exhibited dual emission from both the singlet and triplet states, even at room temperature., Competing Interests: The authors declare no conflict of interest.

A series of phenylsilsesquioxane-benzoate heptacopper complexes 1 - 3 were synthesized and characterized by X-ray crystallography. Two parallel routes of toluene spontaneous oxidation (into benzyl alcohol and benzoate) assisted the formation of the cagelike structure 1 . A unique multi-ligation of copper ions (from ( i ) silsesquioxane, ( ii ) benzoate, ( iii ) benzyl alcohol, ( iv ) pyridine, ( v ) dimethyl-formamide and ( vi ) water ligands) was found in 1 . Directed self-assembly using benzoic acid as a reactant afforded complexes 2 - 3 with the same main structural features as for 1 , namely heptanuclear core coordinated by ( i ) two distorted pentameric cyclic silsesquioxane and ( ii ) four benzoate ligands, but featuring other solvate surroundings. Complex 3 was evaluated as a catalyst for the oxidation of alkanes to alkyl hydroperoxides and alcohols to ketones with hydrogen peroxide and tert-butyl hydroperoxide, respectively, at 50 °C in acetonitrile. The maximum yield of cyclohexane oxidation products as high as 32% was attained. The oxidation reaction results in a mixture of cyclohexyl hydroperoxide, cyclohexanol, and cyclohexanone. Upon the addition of triphenylphosphine, the cyclohexyl hydroperoxide is completely converted to cyclohexanol. The specific regio- and chemoselectivity in the oxidation of n -heptane and methylcyclohexane, respectively, indicate the involvement of of hydroxyl radicals. Complex 3 exhibits a high activity in the oxidation of alcohols.

The first examples of metallasilsesquioxane complexes, including ligands of the 8-hydroxyquinoline family 1 - 9 , were synthesized, and their structures were established by single crystal X-ray diffraction using synchrotron radiation. Compounds 1 - 9 tend to form a type of sandwich-like cage of Cu 4 M 2 nuclearity (M = Li, Na, K). Each complex includes two cisoid pentameric silsesquioxane ligands and two 8-hydroxyquinoline ligands. The latter coordinates the copper ions and corresponding alkaline metal ions (via the deprotonated oxygen site). A characteristic (size) of the alkaline metal ion and a variation of characteristics of nitrogen ligands (8-hydroxyquinoline vs. 5-chloro-8-hydroxyquinoline vs. 5,7-dibromo-8-hydroxyquinoline vs. 5,7-diiodo-8-hydroxyquinoline) are highly influential for the formation of the supramolecular structure of the complexes 3a , 5 , and 7 - 9 . The Cu 6 Na 2 -based compound 2 exhibits high catalytic activity towards the oxidation of ( i ) hydrocarbons by H 2 O 2 activated with HNO 3 , and ( ii ) alcohols by tert -butyl hydroperoxide. Studies of kinetics and their selectivity has led us to conclude that it is the hydroxyl radicals that play a crucial role in this process.

The present study describes a new feature in the self-assembly of cagelike copperphenylsilsesquioxanes: the strong influence of acetone solvates on cage structure formation. By this simple approach, a series of novel tetra-, hexa-, or nonacoppersilsesquioxanes were isolated and characterized. In addition, several new complexes of Cu 4 or Cu 6 nuclearity bearing additional nitrogen-based ligands (ethylenediamine, 2,2'-bipyridine, phenanthroline, bathophenanthroline, or neocuproine) were produced. Single-crystal X-ray diffraction studies established molecular architectures of all of the synthesized products. Several coppersilsesquioxanes represent a novel feature of cagelike metallasilsesquioxane (CLMS) in terms of molecular topology. A Cu 4 -silsesquioxane complex with ethylenediamine (En) ligands was isolated via the unprecedented self-assembly of a partly condensed framework of silsesquioxane ligands, followed by the formation of a sandwich-like cage. Two prismatic Cu 6 complexes represent the different conformers─regular and elliptical hexagonal prisms, "cylinders", determined by the different orientations of the coordinated acetone ligands (" shape-switch effect"). A heterometallic Cu 4 Na 4 -sandwich-like derivative represents the first example of a metallasilsesquioxane complex with diacetone alcohol ligands formed in situ due to acetone condensation reaction. As a selected example, the compound [(Ph 6 Si 6 O 11 ) 2 Cu 4 En 2 ]·(acetone) 2 was explored in homogeneous oxidation catalysis. It catalyzes the oxidation of alkanes to alkyl hydroperoxides with hydrogen peroxide and the oxidation of alcohols to ketones with tert -butyl hydroperoxide. Radical species take part in the oxidation of alkanes. Besides, [(Ph 6 Si 6 O 11 ) 2 Cu 4 En 2 ]·(acetone) 2 catalyzes the mild oxidative functionalization of gaseous alkanes (ethane, propane, n -butane, and i -butane). Two different model reactions were investigated: (1) the oxidation of gaseous alkanes with hydrogen peroxide to give a mixture of oxygenates (alcohols, ketones, or aldehydes) and (2) the carboxylation of C n gaseous alkanes with carbon monoxide, water, and potassium peroxodisulfate to give C n +1 carboxylic acids (main products), along with the corresponding C n oxygenates. For these reactions, the effects of acid promoter, reaction time, and substrate scope were explored. As expected for free-radical-type reactions, the alkane reactivity follows the trend C 2 H 6 < C 3 H 8 < n -C 4 H 10 < i -C 4 H 10 . The highest total product yields were observed in the carboxylation of i -butane (up to 61% based on i -C 4 H 10 ). The product yields and catalyst turnover numbers (TONs) are remarkable, given an inertness of gaseous alkanes and very mild reaction conditions applied (low pressures, 50-60 °C temperatures).

Background: Inefficiency of in vitro fertilization (IVF) programs can be caused by implantation failures. The uterine microbiota can influence the implantation process. However, it still remains unclear whether opportunistic microorganisms detected in the endometrium have a negative impact on the implantation success. The aim of our study was to evaluate the influence of the uterine microbiota on the embryo implantation success in patients undergoing assisted reproductive technologies., Methods: The study included 130 women diagnosed with infertility. The patients were divided into three groups: group I included women with the first IVF attempt (n = 39); group II included patients with recurrent implantation failure following embryo transfer with ovarian stimulation (n = 27); group III consisted of women with recurrent implantation failure following frozen-thawed embryo transfer (n = 64). We performed microbiological examination of the embryo transfer catheter which was removed from the uterine cavity after embryo transfer; cervical discharge of all the patients was studied as well. Thirty patients were selected for metagenomic sequencing., Results: The study showed that the uterine cavity is not free of microorganisms. A total of 44 species of microorganisms were detected: 26 species of opportunistic organisms and 18 species of commensals (14 species of lactobacilli and 4 species of bifidobacteria). Obligate anaerobic microorganisms and Gardnerella vaginalis were detected more frequently in group I compared to group III (strict anaerobes-15.4 and 1.6%; G. vaginalis-12.8 and 1.6%, respectively) (p < 0.05). However, this fact did not have a negative influence on the pregnancy rate: it was 51.3% in group I, it was 29.6% and 35.9% in women with recurrent implantation failures, respectively., Conclusion: Opportunistic microorganisms which were revealed in low or moderate titers (10 3 -10 5  CFU/ml) in the uterine cavity and cervical canal did not affect the pregnancy rate in the women in the study groups. The microflora of the uterine cavity and cervical canal differed in qualitative composition in 87.9% of patients, therefore, we can suggest that the uterine cavity may form its own microbiota. The microbiota of the uterine cavity is characterized by fewer species diversity compared to the microbiota of the cervical canal., (© 2022. The Author(s).)

Low-temperature IR and NMR studies combined with DFT calculations revealed the mechanistic complexity of apparently simple reactions between Mn(I) complex fac -[(dppm)Mn(CO) 3 H] and Lewis acids (LA = Ph 3 C + , B(C 6 F 5 ) 3 ) involving the formation of so-far elusive meridional hydride species mer -[(dppm)Mn(CO) 3 H⋯LA] and unusual dearomatization of the Ph 3 C + cation upon hydride transfer.

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.

A series of emissive Cu(I) cationic complexes with 3-(2-pyridyl)-5-phenyl-pyrazole and various phosphines: dppbz ( 1 ), Xantphos ( 2 ), DPEPhos ( 3 ), PPh 3 ( 4 ), and BINAP ( 5 ) were designed and characterized. Complexes obtained exhibit bright yellow-green emission (ca. 520-650 nm) in the solid state with a wide range of QYs (1-78%) and lifetimes (19-119 µs) at 298 K. The photoluminescence efficiency dramatically depends on the phosphine ligand type. The theoretical calculations of buried volumes and excited states explained the emission behavior for 1 - 5 as well as their lifetimes. The bulky and rigid phosphines promote emission efficiency through the stabilization of singlet and triplet excited states.

New luminescent cage-like tetranuclear silsesquioxanes [NEt 4 ][(Ph 4 Si 4 O 8 ) 2 (Tb 3 Eu)(NO 3 ) 4 (OH)(EtOH) 3 (H 2 O)]·4(EtOH) (1) and [NEt 4 ] 2 [(Ph 4 Si 4 O 8 ) 2 (Tb 2 Eu 2 )(NO 3 ) 6 (EtOH) 2 (MeCN) 2 ]·4(MeCN) (2) present a tunable thermosensitive Tb 3+ -to-Eu 3+ energy transfer driven by Tb 3+ and Eu 3+ emission and may be used as temperature sensors operating in the range 41-100 °C with excellent linearity ( R 2 = 0.9990) and repeatability (>95%). The thermometer performance was evidenced by the maximum relative sensitivity of 0.63% °C -1 achieved at 68 °C., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

The mechanism of the consecutive halogenation of the tetrahydroborate anion [BH 4 ] - by hydrogen halides (HX, X = F, Cl, Br) and hexahydro- closo -hexaborate dianion [B 6 H 6 ] 2- by HCl via electrophile-induced nucleophilic substitution (EINS) was established by ab initio DFT calculations [M06/6-311++G(d,p) and wB97XD/6-311++G(d,p)] in acetonitrile (MeCN), taking into account non-specific solvent effects (SMD model). Successive substitution of H - by X - resulted in increased electron deficiency of borohydrides and changes in the character of boron atoms from nucleophilic to highly electrophilic. This, in turn, increased the tendency of the B-H bond to transfer a proton rather than a hydride ion. Thus, the regularities established suggested that it should be possible to carry out halogenation more selectively with the targeted synthesis of halogen derivatives with a low degree of substitution, by stabilization of H 2 complex, or by carrying out a nucleophilic substitution of B-H bonds activated by interaction with Lewis acids (BL 3 ).

This study reports intriguing features in the self-assembly of cage copper(II) silsesquioxanes in the presence of air. Despite the wide variation of solvates used, a series of prismatic hexanuclear Cu 6 cages ( 1 - 5 ) were assembled under mild conditions. In turn, syntheses at higher temperatures are accompanied by side reactions, leading to the oxidation of solvates (methanol, 1-butanol, and tetrahydrofuran). The oxidized solvent derivatives then specifically participate in the formation of copper silsesquioxane cages, allowing the isolation of several unusual Cu 8 -based ( 6 and 7 ) and Cu 6 -based ( 8 ) complexes. When 1,4-dioxane was applied as a reaction medium, deep rearrangements occurred (with a total elimination of silsesquioxane ligands), causing the formation of mononuclear copper(II) compounds bearing oxidized dioxane fragments ( 9 and 11 ) or a formate-driven 1D coordination polymer ( 10 ). Finally, a "directed" self-assembly of sil- and germsesquioxanes from copper acetate (or formate) resulted in the corresponding acetate (or formate) containing Cu 6 cages ( 12 and 13 ) that were isolated in high yields. The structures of all of the products 1 - 13 were established by single-crystal X-ray diffraction, mainly based on the use of synchrotron radiation. Moreover, the catalytic activity of compounds 12 and 13 was evaluated toward the mild homogeneous oxidation of C 5 -C 8 cycloalkanes with hydrogen peroxide to form a mixture of the corresponding cyclic alcohols and ketones.

The reaction between basic [(PCP)Pd(H)] (PCP = 2,6-(CH 2 P( t -C 4 H 9 ) 2 ) 2 C 6 H 4 ) and acidic [LWH(CO) 3 ] (L = Cp ( 1a ), Tp ( 1b ); Cp = η 5 -cyclopentadienyl, Tp = κ 3 -hydridotris(pyrazolyl)borate) leads to the formation of bimolecular complexes [LW(CO) 2 (μ-CO)⋯Pd(PCP)] ( 4a , 4b ), which catalyze amine-borane (Me 2 NHBH 3 , t BuNH 2 BH 3 ) dehydrogenation. The combination of variable-temperature ( 1 H, 31 P{ 1 H}, 11 B NMR and IR) spectroscopies and computational (ωB97XD/def2-TZVP) studies reveal the formation of an η 1 -borane complex [(PCP)Pd(Me 2 NHBH 3 )] + [LW(CO 3 )] - ( 5 ) in the first step, where a BH bond strongly binds palladium and an amine group is hydrogen-bonded to tungsten. The subsequent intracomplex proton transfer is the rate-determining step, followed by an almost barrierless hydride transfer. Bimetallic species 4 are easily regenerated through hydrogen evolution in the reaction between two hydrides., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Invited for the cover of this issue are Alexey N. Bilyachenko, Joulia Larionova and co-workers at the Russian Academy of Sciences, the Peoples' Friendship University of Russia, and University of Montpellier. The image depicts lanthanide-based cage-like silsesquioxanes exhibiting magnetic and luminescence properties that could constitute a particularly interesting new family related to multifunctional nanomaterials. Read the full text of the article at 10.1002/chem.202003351., (© 2020 Wiley-VCH GmbH.)

The activation of silanes in dehydrogenative coupling with alcohols under general base catalysis was studied experimentally (using multinuclear NMR, IR, and UV-visible spectroscopies) and computationally (at DFT M06/6-311++G(d,p) theory level) on the example of Ph 4- n SiH n ( n = 1-3) interaction with (CF 3 ) 2 CHOH in the presence of Et 3 N. The effect of the phenyl groups' number and H - substitution by the electron-withdrawing (CF 3 ) 2 CHO - group on Si-H bond hydricity (quantified as hydride-donating ability, HDA) and Lewis acidity of silicon atom (characterized by maxima of molecular electrostatic potential) was accessed. Our results show the coordination of Lewis base (Y = Me 3 N, ROH, OR - ) leads to the increased hydricity of pentacoordinate hypervalent Ph 4- n Si(Y)H n complexes and a decrease of the reaction barrier for H 2 release. The formation of tertiary complexes [Ph 4- n Si(Y)H n ]···HOR is a critical prerequisite for the dehydrocoupling with alkoxides being ideal activators. The latter can be external or internal, generated by in situ HOR deprotonation. The mutual effect of tetrel interaction and dihydrogen bonding in tertiary complexes (RO - )Ph 4- n SiH n ···HOR leads to dichotomous activation of Si-H bond promoting the proton-hydride transfer and H 2 release.

Two stereoisomers of pentacoordinate iridium(III) hydridochloride with triptycene-based PC(sp 3 )P pincer ligand (1,8-bis(diisopropylphosphino)triptycene), 1 and 2 , differ by the orientation of hydride ligand relative to the bridgehead ring of triptycene. According to DFT/B3PW91/def2-TZVP calculations performed, an equatorial Cl ligand can relatively easily change its position in 1 , whereas that is not the case in 2 . Both complexes 1 and 2 readily bind the sixth ligand to protect the empty coordination site. Variable temperature spectroscopic (NMR, IR, and UV-visible) studies show the existence of two isomers of hexacoordinate complexes 1 ·MeCN, 2 ·MeCN, and 2 ·Py with acetonitrile or pyridine coordinated trans to hydride or trans to metalated C(sp 3 ), whereas only the equatorial isomer is found for 1 ·Py. These complexes are stabilized by various intramolecular noncovalent C-H···Cl interactions that are affected by the rotation of isopropyls or pyridine. The substitution of MeCN by pyridine is slow yielding axial Py complexes as kinetic products and the equatorial Py complexes as thermodynamic products with faster reactions of 1 ·L. Ultimately, that explains the higher activity of 1 in the catalytic alkenes' isomerization observed for allylbenzene, 1-octene, and pent-4-enenitrile, which proceeds as an insertion/elimination sequence rather than through the allylic mechanism.

Thermodynamic hydricity (HDA MeCN ) determined as Gibbs free energy (ΔG°[H] - ) of the H - detachment reaction in acetonitrile (MeCN) was assessed for 144 small borane clusters (up to 5 boron atoms), polyhedral closo -boranes dianions [B n H n ] 2- , and their lithium salts Li 2 [B n H n ] (n = 5-17) by DFT method [M06/6-311++G(d,p)] taking into account non-specific solvent effect (SMD model). Thermodynamic hydricity values of diborane B 2 H 6 (HDA MeCN = 82.1 kcal/mol) and its dianion [B 2 H 6 ] 2- (HDA MeCN = 40.9 kcal/mol for Li 2 [B 2 H 6 ]) can be selected as border points for the range of borane clusters' reactivity. Borane clusters with HDA MeCN below 41 kcal/mol are strong hydride donors capable of reducing CO 2 (HDA MeCN = 44 kcal/mol for HCO 2 - ), whereas those with HDA MeCN over 82 kcal/mol, predominately neutral boranes, are weak hydride donors and less prone to hydride transfer than to proton transfer (e.g., B 2 H 6 , B 4 H 10 , B 5 H 11 , etc.). The HDA MeCN values of closo -boranes are found to directly depend on the coordination number of the boron atom from which hydride detachment and stabilization of quasi-borinium cation takes place. In general, the larger the coordination number (CN) of a boron atom, the lower the value of HDA MeCN .

Ruthenocene-based PCP tBu pincer ligands were used to synthesize novel pincer palladium chloride Rc F [PCP tBu ]PdCl ( 2a ) and two novel palladium tetrahydroborates Rc F [PCP tBu ]Pd(BH 4 ) ( 3a ) and Rc * [PCP tBu ]Pd(BH 4 ) ( 3b ), where Rc F [PCP tBu ] = κ 3 -{2,5-(tBu 2 PCH 2 ) 2- C 5 H 2 }Ru(Cp F ) (Cp F = C 5 Me 4 CF 3 ), and Rc*[PCP tBu ] = κ 3 -{2,5-(tBu 2 PCH 2 ) 2 C 5 H 2 }Ru(Cp*) (Cp* = C 5 Me 5 ). These coordination compounds were characterized by X-ray, NMR and FTIR techniques. Analysis of the X-ray data shows that an increase of the steric bulk of non-metalated cyclopentadienyl ring in 3a and 3b relative to non-substituted Rc[PCP tBu ]Pd(BH 4 ) analogue ( 3c ; where Rc[PCP tBu ] = κ 3 -{2,5-(tBu 2 PCH 2 ) 2 C 5 H 2 }Ru(Cp), Cp = C 5 H 5 ) pushes palladium atom from the middle plane of the metalated Cp ring in the direction opposite to the ruthenium atom. This displacement increases in the order 3c < 3b < 3a following the order of the Cp-ring steric volume increase. The analysis of both X-ray and IR data suggests that BH 4 ligand in both palladium tetrahydroborates 3a and 3b has the mixed coordination mode η 1,2 . The strength of the BH 4 bond with palladium atom increases in the order Rc[PCP tBu ]Pd(BH 4 ) < Rc*[PCP tBu ]Pd(BH 4 ) < Rc F [PCP tBu ]Pd(BH 4 ) that appears to be affected by both steric and electronic properties of the ruthenocene moiety.

An unusual skeletal rearrangement of piperazine into ethylenediamine has been observed for the first time as a result of an attempt to synthesize a piperazine-linked metal-organic framework (MOF) using cage Cu(II),Na-phenylsilsequixane as a potential building block. Instead of the expected "metallasilsesquioxane-based MOF", a Cu 6 complex 1 coordinated both by silsesquioxane and ethylenediamine ligands was isolated. An effort to reproduce this result via direct interaction of Cu-phenylsilsequioxane and ethylenediamine surprisingly afforded two other types of complexes, copper-sodium 2 and copper 3 ionic products. Cationic components in both products 2 and 3 are represented by (i) copper and sodium ions (in the case of 2 ) or (ii) copper ions exclusively (in the case of 3 ) coordinated by ethylenediamine ligands. Both complexes 2 and 3 include Si 6 -based condensed silsesquioxane fragments serving as anionic components of the products. Symptomatically, the types of the Si 6 -frameworks in 2 and 3 are drastically different. More specifically, the Si 6 unit in 2 is an unprecedented distorted silsesquioxane skeleton consisting of two condensed tetramembered rings. Structural features of compounds 1 - 3 were established by single crystal X-ray diffraction. Compound 2 was found to catalyze the oxidation of cyclohexane to cyclohexanol and cyclohexanone with H 2 O 2 (a mixture of these products was obtained after adding PPh 3 to the reaction solution) as well as the transformation of cyclohexanol to cyclohexanone under the action of tert -butyl hydroperoxide.

Deprotonation of fac-[(κ2P,P-Ph2PCH(R)PPh2)Mn(CO)3Br] (R = H, Me, Ph) produces the corresponding diphosphinomethanide derivatives fac-[(κ3P,C,P-Ph2PC(R)PPh2)Mn(CO)3], which are prone to activate H2 to form the hydride complexes fac-[(κ2P,P-Ph2PCH(R)PPh2)Mn(CO)3H]. The substitution of the dppm bridge improves dramatically the reaction efficiency and this was rationalized by DFT calculations.

Two novel ruthenocene-based pincer palladium tetrahydroborates were characterized by XRD, NMR and FTIR. The alcoholysis of Pd(ii) tetrahydroborate LPd(BH 4 ) (L = κ 3 -[{2,5-( t Bu 2 PCH 2 ) 2 C 5 H 2 }Ru(C 5 H 5 )]) yields the dinuclear cationic Pd(ii) tetrahydroborate with the bridging BH 4 - ligand [(LPd) 2 (μ,η 1,2 :η 1,2 -BH 4 )] + . The bifurcate dihydrogen-bonded complexes are the active intermediates of the first proton transfer in the step-wise alcoholysis of LPd(BH 4 ), yielding eventually [(LPd) 2 (μ,η 1,2 :η 1,2 -BH 4 )] + . According to the X-ray and DFT/M06 geometry analysis, the BH 4 - ligand in both palladium tetrahydroborates has a mixed coordination mode η 1,2 . The possibility of BH 3 -group abstraction from LPd(BH 4 ) by an excess of organic base (THF, Py) with the formation of hydride LPd II H is shown. This Pd(ii) hydride is a very reactive compound able to rapidly capture CO 2 (ca. 15 min) converting into the formate complex LPd II (η 1 -OC(O)H). The hydrolysis of LPdH with subsequent CO 2 insertion yields a hydrocarbonate complex LPd II (η 1 -OC(O)OH). The hydrocarbonate complex forms hydrogen-bonded dimers in the crystal due to hydrogen bonds between the OC(O)OH fragments.

The first example of trinuclear copper(I) and silver(I) pyrazolates adducts with a tertiary diphosphine (Ph 2 PCH 2 PPh 2 ) retaining trimeric [MPz] 3 core is reported. Despite rather strong M-P bonding, the complexes are able to undergo the dissociation of one M-P bond leading to the "merry-go-round" movement of P atoms over the M 3 triangle. The copper complex displays emission from 1 MLCT and 3 MLCT states. The triplet and singlet states are separated by a relatively small energy gap (1080 cm -1 ) that triggers the thermally activated delayed fluorescence (TADF) behavior and leads to the worthy quantum yield of 41% at 298 K. The silver complex in the solid state and frozen solution shows dual emission originating from the 1 IL and 3 MLCT states that is dictated by the much higher energy difference between the emissive singlet and triplet as well as by the essentially different nature of these states.

A set of silver(i) 3,5-bis(trifluoromethyl) pyrazolate adducts with 1,10-phenanthroline (L 2 ), 2,9-dimethyl-1,10-phenanthroline (neocuproine, L 3 ) and 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (bathocuproine, L 4 ) was synthesized starting from trimeric silver pyrazolate Ag 3 Pz 3 . Reactions with sterically hindered L 3 and L 4 cause the destruction of the original trimeric core, yielding a dinuclear Ag 2 Pz 2 cycle with an unprecedented chair configuration for L 3 , while bathocuproine L 4 leads to the drastic rearrangement of the silver pyrazolate core into cationic Ag(L 4 ) 2 and anionic Ag 5 Pz 6 subunits. All complexes obtained exhibit phosphorescence in the solid state. Time-dependent density functional theory calculations demonstrate their different possible emission processes, explaining their emission behavior as well as their lifetimes.

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.

The trinuclear copper(i) pyrazolate {[3,5-(CF3)2Pz]Cu}3 forms η2-copper/alkyne triple bond coordinated structures in the presence of acetylenes. There is no coordination of copper atoms to the phenyl ring of phenylacetylene and copper(i) acetylide formation during the interaction. It was observed that the complexes formed are the active catalytic species in click reactions.

A new "bicycle helmet"-like copper(ii),sodiumphenylsilsesquioxane Ph12Si12O12(OH)(O-)11Cu5Na(bipy)3(H2O) exhibited high catalytic efficiency in two homogeneous reactions: (i) functionalization of C-H compounds; (ii) formation of benzamides from alcohols.

The interaction of a set of mono-, di- and trisubstituted silanes with OH proton donors of different strength was studied by variable temperature (VT) FTIR and NMR spectroscopies at 190-298 K. Two competing sites of proton donors coordination: SiH and π-density of phenyl rings-are revealed for phenyl-containing silanes. The hydrogen bonds SiH⋅⋅⋅HO and OH⋅⋅⋅π(Ph) are of similar strength, but can be distinguished in the ν SiH range: the ν SiH⋅⋅⋅HO vibrations appear at lower frequencies while OH⋅⋅⋅π(Ph) complexes give Si-H vibrations shifted to higher frequency. The calculations showed the manifold picture of the noncovalent interactions in hydrogen-bonded complexes of phenylsilanes. As OH⋅⋅⋅HSi bonds are weak, the other noncovalent interactions compete in the stabilization of the intermolecular complexes. Still, the structural and electronic parameters of "pure" DHB complexes of phenylsilanes are similar to those of Et 3 SiH., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

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).

Unusual high-cluster (Cu 9 ) cage phenylsilsesquioxanes were obtained via complexation of in situ Cu II ,Na-silsesquioxane species formed with phenanthroline and neocuproine. In the first case, phenanthroline, acting as "a silent ligand" (not participating in the composition of the final product), favors the formation of an unprecedented cagelike phenylsilsesquioxane of Cu 9 Na 6 nuclearity, 1. In the second case, neocuproine ligands withdraws two Cu ions from the metallasilsesquioxane matrix, producing two cationic fragments Cu + (neocuproine) 2 . The remaining metallasilsesquioxane is rearranged into an anionic cage of Cu 9 Na 4 nuclearity, finalizing the formation of a specific ionic complex, 2. The impressive molecular architecture of both types of complexes, e.g., the presence of different (cyclic/acyclic) types of silsesquioxane ligands, was established by single-crystal X-ray diffraction studies. Compound 1 was revealed to be highly active in the oxidative amidation of benzylic alcohol and the catalyst loading could be reduced down to 100 ppm of Cu. Catalytic studies of compound 1 demonstrated its high activity in hydroperoxidation of alkanes with H 2 O 2 and oxidation of alcohols to ketones with tert-BuOOH.

The first Ni(ii)-based metallagermaniumsesquioxane cage compound [(PhGeO1.5)10(NiO)4(NaO0.5)2] presents a sandwich-like structure where two germsesquioxane cages are linked through an {NiO}4 core and exhibits slow dynamics of the magnetization.

The interaction of trans-W(N 2 ) 2 (dppe) 2 (1; dppe = 1,2-bis(diphenylphosphino)ethane) with relatively weak acids (p-nitrophenol, fluorinated alcohols, CF 3 COOH) was studied by means of variable temperature IR and NMR spectroscopy and complemented by DFT/B3PW91-D3 calculations. The results show, for the first time, the formation of a hydrogen bond to the coordinated dinitrogen, W-N≡N···H-O, that is preferred over H-bonding to the metal atom, W···H-O, despite the higher proton affinity of the latter. Protonation of the core metal-the undesirable side step in the conversion of N 2 to NH 3 -can be avoided by using weaker and, more importantly, bulkier acids.