The Unusual Structural Behavior of Heteroleptic Aryl Copper(I) Thiolato Molecules : Cis vs Trans Structures and London Dispersion Effects

A series of heteroleptic aryl copper(I) thiolato complexes of formula {Cu2(SAr)Mes}2 (Ar = C6H3-2,6-(C6H2-2,4,6-Me3)2 (ArMe6), 1; C6H3-2,6-(C6H3-2,6-iPr2)2 (AriPr4), 2; C6H3-2,6-(C6H2-2,4,6-iPr3)2 (AriPr6), 3) and {Cu4(SAr)Mes3} (Ar = C6H-2,6-(C6H2-2,4,6-iPr3)2-3,5-iPr2 (AriPr8), 4) were synthesized by the reactions of the corresponding bulky terphenyl thiols with mesitylcopper(I) with elimination of mesitylene. All complexes were characterized by single crystal X-ray diffraction analysis and spectroscopy (NMR, infrared, and UV-vis). The data for 1-3 revealed tetrametallic Cu4 core structures in which two thiolato or two mesityl ligands bridge the metals. Although 1 and 2 feature the expected conventional alternating thiolato and mesityl bridging patterns, 3 has a previously unknown structural arrangement in which the two thiolato ligands are adjacent to each other. Since complex 3 has a more crowding aryl group on the thiolato ligands, the cis arrangement of the ligands in 3 is sterically counterintuitive and is likely due to London dispersion (LD) energy effects. Complex 4 also has an unusual structural pattern in which only a single thiolato ligand is incorporated in the structure probably for steric reasons. It has a planar trapezoidal Cu4 core in which three Cu-Cu edges are bridged by the mesityl groups while the remaining Cu-Cu edge is thiolato ligand bridged. Dispersion connected DFT calculations show that 3 has the highest LD effect stabilization arising from the increased numbers of C-H···H-C interactions of the isopropyl ligand substituents.Peer reviewe

Hydrostannylation of Olefins by a Hydridostannylene Tungsten Complex

Hyväksytty takautuvasti osaksi ACS-OA-sopimusta (APC-tiimi 8. 12. 2022). Lisenssiä ei ollut vielä näkyvissä tallennushetkellä, tullee myöhemmin.Reaction of the aryltin(II) hydride {AriPr6Sn(mu- H)}2 (AriPr6 = -C6H3-2,6-(C6H2-2,4,6-iPr3)2) with two equivalents of the tungsten carbonyl THF complex, [W(CO)5(THF)], afforded the divalent tin hydride transition metal complex, W(CO)5{Sn(AriPr6)H}, (1). Complex 1 reacted rapidly with ethylene, or propylene under ambient conditions to yield the corresponding hydrostannylated organometallic species, W(CO)5{Sn(AriPr6)(Et)} (2), or W(CO)5{Sn(AriPr6)(nPr)} (3), via olefin insertion into the Sn-H bond. Treatment of 1 with the Lewis base dbu (dbu = 1,8-diazabicycloundec-7-ene) afforded the Lewis acid-base complex, W(CO)5{Sn(AriPr6)(dbu)H} (4), indicating that the Lewis acidity of the tin atom is preserved in 4. The complexes were characterized by X-ray crystallography, and by UV-visible, FT-IR, and multinuclear NMR spectroscopies. DFT calculations suggest hydrostannylation of ethylene with 1 proceeds via coordination of ethylene to the tin atom, then insertion into the Sn-H bond. Further computational study on the reactivity of 1 toward Ph3SiH indicated that the rate-determining step involves the metathesis reaction of a Sn-C/Si-H bond with a very high energy barrier of 71.3 kcal/mol. The calculated proton abstraction product of 1 with dbu, [W(CO)5{Sn(AriPr6)}]+[H-(dbu)]-, is 18.2 kcal/mol less stable than the observed coordination product 4.Peer reviewe

Near quantitative conversion of xylose into bisfuran

Renewable and abundant carbohydrates are promising feedstocks for producing valuable chemicals. Here we report a highly efficient Zr-catalysed conversion of xylose and acetylacetone (acac) to a new type of bisfuranic monomer, 1-(4-((4-acetyl-5-methylfuran-2-yl)methyl)-2-methylfuran-3-yl)ethenone (MFE). The formation of MFE stems from the intermediate obtained through the nucleophilic addition of acac to xylose. Under optimized conditions (microwave irradiation, 140 degrees C, 24 min, NaI as an additive), MFE is obtained in near-quantitative yield (98%). Importantly, the reaction selectivity can be tuned by the inclusion of an additive. When NaCl is used, the reaction gives 3-(furan-2-ylmethylene)pentane-2,4-dione (FMPD, 55%), a jet-fuel precursor, and MFE (30%) with a total carbon yield of 85%. To the best of our knowledge, this is the first report on straightforward xylose transformation to a bisfuranic compound with excellent carbon efficiency. This Garcia Gonzalez (GG) reaction inclusive strategy is remarkable and could lead to many innovations in bio-based polymer synthesis.Peer reviewe

Влияние на билкови и имуномодулиращи добавки върху растежните способности и качеството на месото при пилета бройлери

This study aimed to evaluate the effect of herbal and immunomodulatory die-tary supplements and their combinations on growth performance, slaughter traits and meat quality in male broiler chickens. A total of 210 one-day-old Ross 308 male chickens were randomly distributed after weighing in 7 groups (3 replicates in each, n=10 chickens). Broilers were reared on deep litter until 42 days of age and divided as follows: Group I – control (basal diet without supplements); Group II – supple-mented with 0.2% Immunoßeta; Group III – supplemented with 0.2% garlic powder; Group IV – supplemented with 0.2% herbal mix (0.05% ginger, 0.05% rosemary, 0.05% thyme and 0.05% yarrow); Group V – supplemented with 0.2% Immunoßeta + 0.2% garlic powder; Group VI – supplemented with 0.2% Immunoßeta + 0.2% herbal mix; Group VII – supplemented with 0.2% Immunoßeta + 0.2% garlic powder + 0.2% herbal mix. At the end of the experiment, chickens weighed from 2552±54 g (Group I) to 2689±55 g (Group IV) without statistically significant differences (Р>0.05). Feed conversion varied from 1.64 (Group IV) tо 1.74 (Group I). Meat pH, water holding ca-pacity, water absorption capacity, and tenderness were not influenced by the dietary supplement type. All supplements used did not show an adverse effect on health, and no mortality was found in the experimental groups. The obtained results show a clear trend towards a positive effect of the used feed additives and their combination mainly on the fattening characteristics of the broiler chickens, evident from the higher values of the two efficiency indices.Целта на проучването беше да се установи ефекта на някои билкови и имуномодулиращи хранителни добавки поотделно и в комбинация върху растежа, кланичните характеристики и качеството на месото при мъжки пилета бройлери. Общо 210 еднодневни пилета (Ross 308) след претегляне бяха разпределени на случаен принцип в 7 групи (всяка с 3 повторения, n=10 пилета). Бройлерите се отглеждаха върху дълбока постеля до 42-дневна възраст и бяха разделени както следва: Група I – контрола (основна диета без добавки); II група – с добавка на 0,2% Immunoßeta; III група – с добавка на 0,2% чесън на прах; IV група – с добавка на 0,2% билкова комбинация (0,05% джинджифил, 0,05% розмарин, 0,05% мащерка и 0,05% бял равнец); Група V – с добавка на 0,2% Immunoßeta + 0,2% чесън на прах; Група VI – с добавка на 0,2% Immunoßeta + 0,2% билков микс; VII група – допълнена с 0,2% Immunoßeta + 0,2% чесън на прах + 0,2% билков микс. В края на експеримента пилетата достигнаха жива маса от 2552±54 g (I група) до 2689±55 g (IV група) като не се установиха доказани разлики между различните групи (Р>0,05). Конверсията на фураж варираше от 1,64 (IV група) до 1,74 (I група). pH на месото, водозадържащата способност, водопоглъщащата способност и нежността не се повлияха от вида на хранителната добавка. Всички използвани добавки не показаха неблагоприятен ефект върху здравословното състояние, като не беше установена смъртност в експерименталните групи. Получените резултати показват ясна тенденция към положителен ефект на използваните фуражни добавки и тяхното комбиниране основно върху угоителните характеристики на бройлерите, видно от по-високите стойности на двата индекса на ефективност

Anionic Magnesium and Calcium Hydrides : Transforming CO into Unsaturated Disilyl Ethers

OA-artikkeli, mutta ladattaessa tulee hieman erinäköinen versio (esim. ei lisenssiä). Tallennettu kuitenkin OA-artikkelina.The synthesis, characterisation and reactivity of two isostructural anionic magnesium and calcium complexes is reported. By X-ray and neutron diffraction techniques, the anionic hydrides are shown to exist as dimers, held together by a range of interactions between the two anions and two bridging potassium cations. Unlike the vast proportion of previously reported dimeric group 2 hydrides, which have hydrides that bridge two group 2 centres, here the hydrides are shown to be “terminal”, but stabilised by interactions with the potassium cations. Both anionic hydrides were found to insert and couple CO under mild reaction conditions to give the corresponding group 2 cis-ethenediolate complexes. These cis-ethenediolate complexes were found to undergo salt elimination reactions with silyl chlorides, allowing access to small unsaturated disilyl ethers with a high percentage of their mass originating from the C1 source CO.Peer reviewe

Inhibition of Alkali Metal Reduction of 1-Adamantanol by London Dispersion Effects

A series of alkali metal 1-adamantoxide (OAd1) complexes of formula [M(OAd1)(HOAd1)2], where M=Li, Na or K, were synthesised by reduction of 1-adamantanol with excess of the alkali metal. The syntheses indicated that only one out of every three HOAd1 molecules was reduced. An X-ray diffraction study of the sodium derivative shows that the complex features two unreduced HOAd1 donors as well as the reduced alkoxide (OAd1), with the Ad1 fragments clustered together on the same side of the NaO3 plane, contrary to steric considerations. This is the first example of an alkali metal reduction of an alcohol that is inhibited from completion due to the formation of the [M(OAd1)(HOAd1)2] complexes, stabilized by London dispersion effects. NMR spectroscopic studies revealed similar structures for the lithium and potassium derivatives. Computational analyses indicate that decisive London dispersion effects in the molecular structure are a consequence of the many C−H⋅⋅⋅H−C interactions between the OAd1 groups.Peer reviewe

Reversible [4 + 1] Cycloaddition of Arenes by a “Naked” Acyclic Aluminyl Compound

The large steric profile of the N-heterocyclic boryloxy ligand, –OB­(NDippCH)2, and its ability to stabilize the metal-centered HOMO, are exploited in the synthesis of the first example of a “naked” acyclic aluminyl complex, [K­(2.2.2-crypt)]­[Al­{OB­(NDippCH)2}2]. This system, which is formed by substitution at AlI (rather than reduction of AlIII), represents the first O-ligated aluminyl compound and is shown to be capable of hitherto unprecedented reversible single-site [4 + 1] cycloaddition of benzene. This chemistry and the unusual regioselectivity of the related cycloaddition of anthracene are shown to be highly dependent on the availability (or otherwise) of the K+ countercation

Landscape homogenization due to agricultural intensification disrupts the relationship between reproductive success and main prey abundance in an avian predator

Selecting high-quality habitat and the optimal time to reproduce can increase individual fitness and is a strong evolutionary factor shaping animal populations. However, few studies have investigated the interplay between land cover heterogeneity, limitation in food resources, individual quality and spatial variation in fitness parameters. Here, we explore how individuals of different quality respond to possible mismatches between a cue for prey availability (land cover heterogeneity) and the actual fluctuating prey abundance.Peer reviewe

Oxidative Addition or Werner Coordination Complex? Reactivity of β-diketiminate Supported Main Group and First-row Transition Metal Complexes towards Ammonia : Reactivity of beta-diketiminate supported main group and first-row transition metal complexes towards ammonia

Peer reviewe