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The loss of nutrients from conventional fertilisers is often encountered by the agricultural industry. Slowrelease fertilisers by nanotechnology application can maintain nutrient availability for effective plant growth. Zinc-layered hydroxide nanohybrids have been little explored as controlled release systems of functional anions, unlike the Layered Double Hydroxides (LDH) that belong to the same family of anionic clays. The objective of the study was to investigate the effectiveness of zinc-layered hydroxide nanohybrid containing plant nutrient anions as a controlled-release formulation. Two nano-delivery materials namely zinc-layered hydroxide nitrate (ZLN) and zinc-layered hydroxide phosphate (ZLP) were successfully synthesised through the co-precipitation and anion exchange methods. The PXRD patterns of the resulting nanohybrids, ZLN and ZLP recorded basal spacing of 9.57 and 6.78Å, respectively, at a lower 2Ѳ angles range of 0-60°. FTIR analyses confirmed the formation of host-guest nanohybrid which comprised the characteristic bands of nitrate and phosphate. Thermogravimetric analyses showed the thermal stability of the nanohybrid obtained where the capability of the host material to function as a controlled release agent was determined through a controlled release study. Controlled release of plant nutrient sources, nitrate and phosphate from their respective nanohybrids were evaluated using various release medium solutions. The accumulated release of guest anion from interlayer zinc layered hydroxide (ZLH) nanohybrid into pH 4 solution was observed to be faster than pH 6.5. A higher concentration of sodium carbonate solution showed an increase in the percentage release for both nitrate and phosphate anions into the release medium. A plant growth trial using Kelempayan (Neolamarckia cadamba) seedlings showed that treatment with ZLN and ZLP recorded the highest biomass weight compared to application with commercial fertiliser and raw chemicals. The content of N, P and Zn in Kelempayan leaves showed the highest readings for similar treatment. The study found that ZLH has acted as a good host for inorganic plant nutrients with slow-release properties and thus has improved the growth performance of Kelempayan seedlings with better nutrient uptake. [ABSTRACT FROM AUTHOR]

The reaction of terminal zinc hydrides with palladium(0) species afforded an unprecedented [η2-Zn2Pd] trimetallic complex through the reductive elimination of H2. In contrast, the reaction of zinc hydrides with a nickel(0) reagent gave σ-Zn–H coordination complexes with no direct Zn–Zn bonding. Computational studies indicated that an oxidative addition/reductive elimination process at the palladium center might be responsible for the formation of a covalent Zn–Zn bond. [ABSTRACT FROM AUTHOR]

Zinc oxide has been developed as a catalyst for the dehydrogenation of primary alcohols into carboxylic acids and hydrogen gas. The reaction is performed in mesitylene solution in the presence of potassium hydroxide, followed by workup with hydrochloric acid. The transformation can be applied to both benzylic and aliphatic primary alcohols and the catalytically active species was shown to be a homogeneous compound by a hot filtration test. Dialkylzinc and strongly basic zinc salts also catalyze the dehydrogenation with similar results. The mechanism is believed to involve the formation of a zinc alkoxide which degrades into the aldehyde and a zinc hydride. The latter reacts with the alcohol to form hydrogen gas and regenerate the zinc alkoxide. The degradation of a zinc alkoxide into the aldehyde upon heating was confirmed experimentally. The aldehyde can then undergo a Cannizzaro reaction or a Tishchenko reaction, which in the presence of hydroxide leads to the carboxylic acid. Catalysis at a bargain: Zinc oxide catalyzes the dehydrogenation of primary alcohols into carboxylic acids with the release of hydrogen gas. It constitutes the most inexpensive catalyst for the acceptorless alcohol dehydrogenation in solution, where the catalytically active species most likely is a zinc alkoxide. [ABSTRACT FROM AUTHOR]

Catalytic liquefaction is an effective method for bio-crude production, but the development of efficient catalysts remains a challenge. Bifunctional Co/HZSM-5, Zn/HZSM-5 and Co-Zn/HZSM-5 catalysts were integrated with zinc hydrolysis to produce upgraded bio-crude. Co or Zn modified HZSM-5 catalysts improved the yields of bio-crude and gas compared to no catalyst treatment. Co or Zn modified HZSM-5 catalysts decreased the contents of oxygenated compounds including ketones, acids, alcohols and phenols. Co or Zn loaded HZSM-5 catalysts improved the hydrocarbons contents. Compared to monometallic Co/HZSM-5 and Zn/HZSM-5, bimetallic Co-Zn/HZSM-5 generated bio-crude with higher quality due to the synergistic effect of Co and Zn on HZSM-5 support. Co-Zn/HZSM-5 produced the highest bio-crude yield at 67.38 wt%, and the highest hydrocarbons content of bio-crude produced was 18.59%. [ABSTRACT FROM AUTHOR]

Abstract: The terminal zinc hydride complex [Tntm]ZnH (2; Tntm=tris(6‐tert‐butyl‐3‐thiopyridazinyl)methanide) is an efficient hydrosilylation catalyst of CO2 at room temperature without the need of Lewis acidic additives. The inherent electrophilicity of the system leads to selective formation of the monosilylated product (MeO)3SiO2CH (at room temperature with a TOF of 22.2 h−1 and at 45 °C with a TOF of 66.7 h−1). In absence of silanes, the intermediate formate complex [Tntm]Zn(O2CH) (3) is quantitatively formed within 5 min. All complexes were fully characterized by 1H and 13C NMR spectroscopy and single‐crystal X‐ray diffraction analyses. Density functional theory (DFT) calculations reveal a high positive charge on zinc and the increased preference of the ligand to adopt a κ3‐coordination mode. [ABSTRACT FROM AUTHOR]

A series of zinc dihalides [(IMes)ZnX2] [X = Cl (1a) Br (1b), I (1c); IMes = 1,3-bis(2,4,6-trimethylphenyl)imidazolin-2-ylidene] is reported. The iodide 1c underwent salt metathesis with NaH as an alternative synthesis of [(IMes)ZnH2]2 (2). 2 readily reacted with (tBu)NCO and Ph2CO under Zn-H insertion to give [(IMes)Zn(tBuNCHO-kN)2] (3) and [(IMes)Zn(OCHPh2)2] (4), respectively. Ph2S2 and I2 oxidized the hydride ligands in 2 to give dihydrogen and [(IMes)Zn(SPh)2] (5) and 1c, respectively. A series of mixed halo hydrides [(IMes)Zn(X)(H)]2 [X = Cl (6a), Br (6b), I (6c)] was obtained upon comproportionating 2 with 1a-c. The new compounds were fully characterized, including X-ray crystallographic analysis of 3 and 6b. [ABSTRACT FROM AUTHOR]

Zinc hydroxystannate (ZHS) was fabricated on the surface of amorphous hydrous TiO 2 solid spheres (AHTSS) via a layer-by-layer method for improving the fire safety of epoxy resin. AHTSS@PEI@ZHS was prepared by self-assembly of AHTSS, PEI and ZHS. The well-organized fabrication process was proved by TEM, XPS, XRD and SEM tests. TG results illustrated that the incorporation of AHTSS@PEI@ZHS show a higher residue compared with the addition of AHTSS or ZHS alone. In addition, AHTSS@PEI@ZHS filled EP composites exhibits improved flame retardancy and smoke suppression properties evaluated by cone calorimeter test. TG-IR results also indicated that the catalytic labyrinth structure of AHTSS@PEI@ZHS can effectively decrease the permeation of volatile organic compounds, thereby improving the fire safety of EP resin. [ABSTRACT FROM AUTHOR]

Formate, as an excellent hydrogen-storage material, has recently become increasingly important because formate has low toxicity, is easy to store and transport, and contains relatively high energy density. In this paper, we give an overview of the recent strategies in the conversion of bicarbonate into formate by water splitting with a general metallic Zn powder, which mainly includes: (1) hydrogen production from water with Zn; (2) formate syntheses from bicarbonate with water-derived hydrogen; (3) catalytic role of ZnO and Zn/ZnO interface and reducing role of active intermediate of Zn hydride species (Zn-H); (4) density function theory calculation for formate synthesis from bicarbonate and water with Zn; (5) solar-to-chemical energy conversion efficiency estimation. The novel options of this proposed strategy are mainly the hydrogen being in situ formed from water with metal Zn as a reductant, and the plausible autocatalytic reaction mechanism. When coupled with reducing ZnO into Zn by solar energy, a highly efficient solar-fuel process can be expected. [ABSTRACT FROM AUTHOR]

Through a dramatic advance in the coordination chemistry of the zinc-hydride bond, we describe the trajectory for the approach of this bond to transition metals. The dynamic reaction coordinate was interrogated through analysis of a series of solid state structures and is one in which the TM-H-Zn angle becomes increasingly acute as the TM-Zn distance decreases. Parallels may be drawn with the oxidative addition of boron-hydrogen and silicon-hydrogen bonds to transition metal centers. [ABSTRACT FROM AUTHOR]

An overview of structurally characterized molecular organozinc hydrides is given. The compounds are presented based on the type of supporting ligand. Their synthesis, structure, reactivity, and catalytic applications are summarized in this overview. [ABSTRACT FROM AUTHOR]

A high-level ab initio calculation on the ZnH + cation has been carried out with the multi-reference configuration interaction method plus Davison correction (MRCI + Q). The scalar relativistic effect is included by using the Douglas–Kroll–Hess (DKH) method. The calculated potential energy curves (PECs) of the 7 Λ–S states are associated with the dissociation limits of Zn + ( 2 S g ) + H( 2 S g ), Zn( 1 S g ) + H + ( 1 S g ), and Zn + ( 2 P u ) + H( 2 S g ), respectively (The Λ–S state is labeled as 2S + 1 Λ, in which Λ is the quantum number for the projection along the internuclear axis of the total electronic orbital angular momentum and S is the total electron spin). The spectroscopic constants of the bound states are determined and in good agreement with the available theoretical and experimental results. The permanent dipole moments (PDMs) of Λ–S states and the spin–orbit (SO) matrix elements between Λ–S states are also computed. The results show that the abrupt changes of the PDMs and SO matrix elements come into being for the reason of the avoided crossing between the states with the same symmetry. In addition, the non-adiabatic couplings matrix elements between Λ–S states are also evaluated. Finally, the spin–orbit couplings (SOCs) for the low-lying states are considered with Breit-Pauli operator. The SOC effect makes the 7 Λ–S states of the ZnH + cation split into 12 Ω states (Ω = Λ + S z , in which S z is projection of the total electron spin S along the internuclear Z-axis). For the (3)0 + state, the two energy minima exhibit in the potential, which could be attributed to the formation of the new avoided crossing point. The transition dipole moments (TDMs), Franck–Condon factors, and the radiative lifetimes of the selected transitions (2)0 + -X0 + , (3)0 + -X0 + , (2)1-X0 + and (3)1-X0 + have been reported. [ABSTRACT FROM AUTHOR]

The first terminal zinc hydride complex that features a sulfur-rich coordination environment, namely the tris(2-mercapto-1-tert-butylimidazolyl)hydroborato compound, [TmBut]ZnH, has been synthesized via the reaction of [TmBut]ZnOPh with PhSiH3. The Zn–H bond of [TmBut]ZnH is subject to insertion of CO2 and facile protolytic cleavage, of which the latter provides access to heterobimetallic [TmBut]ZnMo(CO)3Cp. [ABSTRACT FROM AUTHOR]

The terminal zinc hydride complex, [ T p Bu t ,Me ]ZnH, can be conveniently obtained from the hydroxide derivative, [ T p Bu t ,Me ]ZnOH, by reaction with H 3 NBH 3 . The zinc hydride complex [ T p Bu t ,Me ]ZnH is reactive and the Zn–H bond undergoes (i) insertion of CO 2 to produce the formate complex, [ T p Bu t ,Me ]Zn(κ 1 –O 2 CH), (ii) protolytic cleavage with Me 3 SiOH to afford [ T p Bu t ,Me ]ZnOSiMe 3 , and (iii) metathesis with Me 3 SnF to form the zinc fluoride derivative, [ T p Bu t ,Me ]ZnF. The fluoride derivative, which may also be formed by the reactions of [ T p Bu t ,Me ]ZnOH with [Me 3 O][BF 4 ] or Me 3 SnF, can be converted back to [ T p Bu t ,Me ]ZnH upon treatment with either H 3 NBH 3 or (MeO) 3 SiH. [ABSTRACT FROM AUTHOR]

Local perturbations observed in the 01 1 1 ( Π g ) → 01 1 0 ( Π u ) hot bands of 64 ZnH 2 , 66 ZnH 2 , 68 ZnH 2 , 64 ZnD 2 and 66 ZnD 2 have been analyzed. The 01 1 1 ( Π g ) state is perturbed by the nearby 040 vibrational level that contains 04 4 0 ( Γ g ), 04 2 0 ( Δ g ) and 04 0 0 ( Σ g + ) states. Appropriate Hamiltonian matrices were constructed in which the effects of rotational ℓ -type doubling, ℓ -type resonance and Coriolis interaction were taken into account, and nonlinear least squares fits were performed. Unperturbed constants were obtained for the 01 1 1 ( Π g ) states, along with vibrational energies of the 040 (perturbing) levels and the Coriolis interaction coefficients. Relative vibrational energies of the 040 and 030 levels were then used to estimate the origins of the bending mode fundamental bands, resulting in ν 2 vibrational wavenumbers of 634.45 cm −1 and 459.14 cm −1 , for 64 ZnH 2 and 64 ZnD 2 , respectively. [ABSTRACT FROM AUTHOR]

Tris(2-pyridylthio)methyl zinc hydride, [κ3-Tptm]ZnH, is an effective catalyst for multiple insertions of carbonyl groups into the Si-H bonds of PhxSiH4-x (x = 1, 2). Specifically, [κ3-Tptm]ZnH catalyzes the insertion of a variety of aldehydes and ketones into the Si-H bonds of PhSiH3 and Ph2SiH2 to afford PhSi[OCH(R)R']3 and Ph2Si[OCH(R)R']2, respectively. The mechanism for hydrosilylation is proposed to involve insertion of the carbonyl group into the Zn-H bond to afford an alkoxy species, followed by metathesis with the silane to release the alkoxysilane and regenerate the zinc hydride catalyst. Multiple insertion of prochiral ketones results in the formation of diastereomeric mixtures of alkoxysilanes that can be identified by NMR spectroscopy. [ABSTRACT FROM AUTHOR]

Tris(2-pyridylthio)methylzinc hydride, [κ3-Tptm]ZnH,is an effective catalyst for multiple insertions of carbonyl groupsinto the Si–H bonds of PhxSiH4–x(x= 1, 2). Specifically,[κ3-Tptm]ZnH catalyzes the insertion of a varietyof aldehydes and ketones into the Si–H bonds of PhSiH3and Ph2SiH2to afford PhSi[OCH(R)R′]3and Ph2Si[OCH(R)R′]2, respectively.The mechanism for hydrosilylation is proposed to involve insertionof the carbonyl group into the Zn–H bond to afford an alkoxyspecies, followed by metathesis with the silane to release the alkoxysilaneand regenerate the zinc hydride catalyst. Multiple insertion of prochiralketones results in the formation of diastereomeric mixtures of alkoxysilanesthat can be identified by NMR spectroscopy. [ABSTRACT FROM AUTHOR]

A soft porous material [Zn(L)2(OH)2]n·Guest (where L is 4-(1H-naphtho[2,3-d]imidazol-1-yl)benzoate, and Guest is water or methanol) exhibits the strongest ever observed negative area compressibility (NAC), an extremely rare property, as at hydrostatic pressure most materials shrink in all directions and few expand in one direction. This is the first NAC reported in metal-organic frameworks (MOFs), and its magnitude, clearly visible and by far the highest of all known materials, can be reversibly tuned by exchanging guests adsorbed from hydrostatic fluids. This counterintuitive strong NAC of [Zn(L)2(OH)2]n·Guest arises from the interplay of flexible [-Zn-O(H)-]n helices with layers of [-Zn-L-]4 quadrangular puckered rings comprising large channel voids. The compression of helices and flattening of puckered rings combine to give a giant piezo-mechanical response, applicable in ultrasensitive sensors and actuators. The extrinsic NAC response to different hydrostatic fluids is due to varied host-guest interactions affecting the mechanical strain within the range permitted by exceptionally high flexibility of the framework. [ABSTRACT FROM AUTHOR]

The reaction of [Zn3Cl3 L], in which L3− is a tris(β-diketiminate) cyclophane, with K( sBu)3BH afforded [Zn3(μ-H)3 L] ( 2), as confirmed by NMR spectroscopy, NOESY, and X-ray crystallography. The complex 2 was air-stable and unreactive towards water, methanol, and other substrates (e.g., nitriles) at room temperature over 24 h but reacted with CO2 (ca. 1 atm) to generate [Zn3(μ-H)2(μ-1,1-O2CH)] ( 3). In contrast, [Zn3(OH)3 L] ( 4) was found to be unreactive toward CO2 over the course of several days at 90 °C. [ABSTRACT FROM AUTHOR]

The reaction of [Zn3Cl3 L], in which L3− is a tris(β-diketiminate) cyclophane, with K(sBu)3BH afforded [Zn3(μ-H)3L] (2), as confirmed by NMR spectroscopy, NOESY, and X-ray crystallography. The complex 2 was air-stable and unreactive towards water, methanol, and other substrates (e.g., nitriles) at room temperature over 24 h but reacted with CO2 (ca. 1 atm) to generate [Zn3(μ-H)2(μ-1,1-O2CH)] (3). In contrast, [Zn3(OH)3L] (4) was found to be unreactive toward CO2 over the course of several days at 90°C. [ABSTRACT FROM AUTHOR]

The reaction of [Zn3Cl3 L], in which L3− is a tris(β-diketiminate) cyclophane, with K( sBu)3BH afforded [Zn3(μ-H)3 L] ( 2), as confirmed by NMR spectroscopy, NOESY, and X-ray crystallography. The complex 2 was air-stable and unreactive towards water, methanol, and other substrates (e.g., nitriles) at room temperature over 24 h but reacted with CO2 (ca. 1 atm) to generate [Zn3(μ-H)2(μ-1,1-O2CH)] ( 3). In contrast, [Zn3(OH)3 L] ( 4) was found to be unreactive toward CO2 over the course of several days at 90 °C. [ABSTRACT FROM AUTHOR]

The reaction of [Zn3Cl3 L], in which L3− is a tris(β-diketiminate) cyclophane, with K(sBu)3BH afforded [Zn3(μ-H)3L] (2), as confirmed by NMR spectroscopy, NOESY, and X-ray crystallography. The complex 2 was air-stable and unreactive towards water, methanol, and other substrates (e.g., nitriles) at room temperature over 24 h but reacted with CO2 (ca. 1 atm) to generate [Zn3(μ-H)2(μ-1,1-O2CH)] (3). In contrast, [Zn3(OH)3L] (4) was found to be unreactive toward CO2 over the course of several days at 90°C. [ABSTRACT FROM AUTHOR]

Density functional theory (DFT) studyof the reactions of mononuclearphenolate diamine zinc hydride complexes and CO2revealsa direct insertion mechanism with a rate-determining C–H bondformation step. A total of 16 zinc hydride complexes with variousfunctional groups, including 3 experimental structures and 13 newlyproposed complexes, have been optimized. The influences of varioussubstituents at different positions, the ring size of nitrogen bidentateligands, and the ortho groups of nitrogen on the reaction rate areinvestigated. Computational results indicate that the ortho effectof nitrogen is the most effective factor in reducing the reactionenergy barrier, and the complex with isopropyls as the ortho groupsof the nitrogen atom has the lowest barrier of 10.9 kcal/mol. [ABSTRACT FROM AUTHOR]

The trinuclear cationic zinc hydride cluster [(IMes)3Zn3H4(THF)](BPh4)2 ( 1) was obtained either by protonation of the neutral zinc dihydride [(IMes)ZnH2]2 with a Brønsted acid or by addition of the putative zinc dication [(IMes)Zn(THF)]2+. A triply bridged thiophenolato complex 2 was formed upon oxidation of 1 with PhSSPh. Protonolysis of 1 by methanol or water gave the corresponding trinuclear dicationic derivatives. At ambient temperature, 1 catalyzed the hydrosilylation of aldehydes, ketones, and nitriles. Carbon dioxide was also hydrosilylated under forcing conditions when using (EtO)3SiH, giving silylformate as the main product. [ABSTRACT FROM AUTHOR]

We present isolable examples of formal zinc hydride cations supported by N-heterocyclic carbene (NHC) donors, and investigate the dual electrophilic and nucleophilic (hydridic) character of the encapsulated [ZnH]+ units by computational methods and preliminary hydrosilylation catalysis. [ABSTRACT FROM AUTHOR]

Generation of H2 from methanol/water and hydrosilylation of CO2 catalyzed by [tris(2-pyridylthio)methyl]zinc hydride [κ³-Tptm]ZnH 1 were investigated with DFT and MP2 methods. The hydrosilylation of CO2 occurs via the CO2 insertion into the Zn-H bond of 1 followed by the metathesis of a Zn-(η¹-OCOH) bond with hydrosilane to yield silyl formate and regenerate 1. The CO2 insertion easily occurs, but the metathesis is difficult because of the formation of a very stable Zn-(η²-O2CH) species before the metathesis. The ΔGº‡ value of the metathesis with triethoxysilane is much smaller than that with phenylsilane because electronegative methoxy groups stabilize the transition state bearing hypervalent Si center, which is consistent with the experimental result that triethoxysilane is used in the hydrosilylation of C O2. It is theoretically predicted here that hydrosilane with two electronegative OEt groups or one to three F groups can be applied to this reaction. In the generation of H2 from methanol/water by 1, the first step is the metathesis of 1 with the O-H bond of methanol/water to produce [κ³-Tptm]Zn(OMe)/[k³-Tptm]Zn(OH) and dihydrogen molecule. The next step is the metathesis of the Zn-OMe/ Zn-OH bond with hydrosilane to yield silyl ether and regenerate 1. The first metathesis is rate-determining but the second one occurs with very small activation energy, indicating that various hydrosilanes can be applied to this reaction. [ABSTRACT FROM AUTHOR]

Postsynthetic metal and ligand exchange is a versatile approach towards functionalized MFU-4 l frameworks. Upon thermal treatment of MFU-4 l formates, coordinatively strongly unsaturated metal centers, such as zinc(II) hydride or copper(I) species, are generated selectively. CuI-MFU-4 l prepared in this way was stable under ambient conditions and showed fully reversible chemisorption of small molecules, such as O2, N2, and H2, with corresponding isosteric heats of adsorption of 53, 42, and 32 kJ mol−1, respectively, as determined by gas-sorption measurements and confirmed by DFT calculations. Moreover, CuI-MFU-4 l formed stable complexes with C2H4 and CO. These complexes were characterized by FTIR spectroscopy. The demonstrated hydride transfer to electrophiles and strong binding of small gas molecules suggests these novel, yet robust, metal-organic frameworks with open metal sites as promising catalytic materials comprising earth-abundant metal elements. [ABSTRACT FROM AUTHOR]

The synthesis, characterization,and zinc coordination chemistryof the three proligands 2-tert-butyl-4-[tert-butyl (1)/methoxy (2)/nitro (3)]-6-{[(2′-dimethylaminoethyl)methylamino]methyl}phenol aredescribed. Each of the ligands was reacted with diethylzinc to yieldzinc ethyl complexes 4–6; these complexeswere subsequently reacted with phenylsilanol to yield zinc siloxidecomplexes 7–9. Finally, the zincsiloxide complexes were reacted with phenylsilane to produce the threenew zinc hydride complexes 10–12.The new complexes 4–12have beenfully characterized by NMR spectroscopy, mass spectrometry, and elementalanalyses. The structures of the zinc hydride complexes have been probedusing VT-NMR spectroscopy and X-ray diffraction experiments. Thesedata indicate that the complexes exhibit mononuclear structures at298 K, both in the solid state and in solution (d8-toluene). At 203 K, the NMR signals broaden, consistentwith an equilibrium between the mononuclear and dinuclear bis(μ-hydrido)complexes. All three zinc hydride complexes react rapidly and quantitativelywith carbon dioxide, at 298 K and 1 bar of pressure over 20 min, toform the new zinc formate complexes 13–15. The zinc formate complexes have been analyzed by NMR spectroscopyand VT-NMR studies, which reveal a temperature-dependent monomer–dimerequilibrium that is dominated by the mononuclear species at 298 K. [ABSTRACT FROM AUTHOR]

Methylene-linked bis( N, N′-di- tert-butylimidazol-2-ylidene) 1 reacted with diethylzinc to give dinuclear zinc ethyl compound 2, which contains a formally anionic bis(carbene) ligand as a result of deprotonation of the methylene bridge. The reaction of 2 with PhSiH3 gave the phenylsilyl compound 3. The zinc hydride 4 was obtained by the reaction of 2 with LiAlH4 or Ph3SiOH followed by treatment with PhSiH3. X-ray diffraction studies show that compounds 2, 3, and 4 all have a similar dimeric structure with D2 h symmetry. The reaction of hydride 4 with carbon dioxide and N, N′-diisopropylcarbodiimide gave formato ( 5) and formamidinato ( 7) derivatives as a result of the insertion of the heterocumulene into both ZnH bonds. Reaction with Ph2CO gave the diphenylmethoxy compound 6. Hydride 4 shows catalytic activity in the hydrosilylation of 1,1-diphenylethylene and methanolysis of silanes. [ABSTRACT FROM AUTHOR]

Efflux pumps belonging to the ubiquitous resistance–nodulation–cell division (RND) superfamily transport substrates out of cells by coupling proton conduction across the membrane to a conformationally driven pumping cycle. The heavy metal-resistant bacteria Cupriavidus metallidurans CH34 relies notably on as many as 12 heavy metal efflux pumps of the RND superfamily. Here we show that C. metallidurans CH34 ZneA is a proton driven efflux pump specific for Zn(II), and that transport of substrates through the transmembrane domain may be electrogenic. We report two X-ray crystal structures of ZneA in intermediate transport conformations, at 3.0 and 3.7 Å resolution. The trimeric ZneA structures capture protomer conformations that differ in the spatial arrangement and Zn(II) occupancies at a proximal and a distal substrate binding site. Structural comparison shows that transport of substrates through a tunnel that links the two binding sites, toward an exit portal, is mediated by the conformation of a short 14-aa loop. Taken together, the ZneA structures presented here provide mechanistic insights into the conformational changes required for substrate efflux by RND superfamily transporters. [ABSTRACT FROM AUTHOR]

The article presents a study which aims to investigates the reactivity of decamethylzincocene with various N-heterocyclic carbenes (NHCs) that yields an adduct or a sterically Lewis pair. It says that the cleavage of dihydrogen can be affected in the presence or absence of NHCs. Moreover, the isolation of a monomeric zinc hydride from catalytic experiments proposes substrate insertion into the zinc and hydrogen bond is the main step in the reduction of the carbon and nitrogen double bond.

Abstract: Density functional theory calculations have been used to investigate the structural stability, electronic characteristics and thermodynamic properties of K2ZnH4 hydride. We find that the orthorhombic structure of K2ZnH4 is more stable than the tetragonal structure base on the total energy and phonon density of states. The calculated lattice parameters of the orthorhombic structure of K2ZnH4 are in good agreement with the experimental data. Analysis of the electronic characteristic suggests that K2ZnH4 crystal is an insulating material with a band gap of 4.010eV. The calculated average H site energy is 4.540eV/H, demonstrating that strong covalent bond exist between Zn and H atom. The formation enthalpy of K2ZnH4 is found to be −1.318eV/f.u at 298K. Hydrogen desorption from K2ZnH4 takes place via a two-step process, firstly forming KH, Zn and H2, and then K and H2. The first decomposition reaction is predicted at 524K, and the second decomposition reaction is at 505K. The reaction enthalpy is estimated to be 49.164kJ/mol at 524K for the first decomposition reaction, and 62.523kJ/mol at 505K for the second decomposition reaction. [Copyright &y& Elsevier]

[Tris(2-pyridylthio)methyl]zinc hydride, [κ3-Tptm]ZnH, is a multifunctional catalyst that is capable of achieving (i) rapid release of hydrogen by protolytic cleavage of silanes with either water or methanol and (ii) hydrosilylation of aldehydes, ketones, and carbon dioxide. For example, [κ3-Tptm]ZnH catalyzes the release of 3 equivalents of H2 by methanolysis of phenylsilane, with a turnover number of 105 and a turnover frequency surpassing 106 h-1 for the first 2 equivalents. Furthermore, [κ3-Tptm]ZnH also catalyzes the formation of triethoxysilyl formate by hydrosilylation of carbon dioxide with triethoxysilane. Triethoxysilyl formate may be converted into ethyl formate and N,N-dimethylformamide, thereby providing a means for utilizing carbon dioxide as a C1 feedstock for the synthesis of useful chemicals. [ABSTRACT FROM AUTHOR]

The first examples of essentially two-coordinate, monomeric zinc hydride complexes, LZnH (L = –N(Ar)(SiR3)) (Ar = C6H2{C(H)Ph2}2R′-2,6,4; R = Me, R′ = Pri (L′); R = Pri, R′ = Me (L*); R = Pri, R′ = Pri (L†)) have been prepared and shown by crystallographic studies to have near linear N–Zn–H fragments. The results of computational studies imply that any Ph…Zn interactions in the compounds are weak at best. Preliminary reactivity studies reveal the compounds to be effective for the stoichiometric hydrozincation and catalytic hydrosilylation of carbonyl compounds. [ABSTRACT FROM AUTHOR]

Review: synthesis, structure, reactivity, and catalytic applications of organozinc hyrides; 67 refs. [ABSTRACT FROM AUTHOR]

Convenient syntheses for a β-diketiminate zinc hydride complex, that crystallizes as a monomer with a three-coordinate Zn atom, have been developed. [ABSTRACT FROM AUTHOR]

The reaction of [Zn3Cl3L], in which L(3-) is a tris(β-diketiminate) cyclophane, with K(sBu)3BH afforded [Zn3(μ-H)3L] (2), as confirmed by NMR spectroscopy, NOESY, and X-ray crystallography. The complex 2 was air-stable and unreactive towards water, methanol, and other substrates (e.g., nitriles) at room temperature over 24 h but reacted with CO2 (ca. 1 atm) to generate [Zn3(μ-H)2(μ-1,1-O2CH)] (3). In contrast, [Zn3(OH)3L] (4) was found to be unreactive toward CO2 over the course of several days at 90 °C., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)