Hydride Complexes Research Articles

Theoretical Investigation of Interconversion Pathways and Intermediates in Hydride/Silyl Exchange of Niobocene Hydride–Silyl Complexes: A DFT Study Incorporating Conformational Search and Interaction Region Indicator (IRI) Analysis

Niobocene hydride–silyl complexes exhibit intriguing structural characteristics with the potential for direct hydride/silyl exchange, where hydride migration plays a crucial role during conformational interconversion. In this study, quantum chemical calculations were utilized to investigate the transformation pathways involved in hydride/silyl exchange in niobocene trihydride complexes with various dichlorosilanes, including SiCl2Me2, SiCl2iPr2, and SiCl2MePh ligands. The conformational changes and hydride shifts within these niobocene hydride–silyl complexes were examined, and key intermediates were identified. Electronic wavefunction analysis provided insights into the coordination configurations and the nature of inter-ligand interactions. Interaction region indicator (IRI) analysis revealed Van der Waals interactions between chloride atoms and cyclopentadienyl rings, as well as between chloride atoms and Me, iPr, and Ph groups. Notably, distinct interactions between hydride ligands, including those from Si-H moieties and coordinated hydrogen atoms, were observed. Both lateral and central conformations, with respect to silicon coordination to the niobium center, were considered. This study enhances the understanding of intermediate conformations in the hydride/silyl exchange process and provides a detailed characterization of inter-ligand interactions, offering valuable insights for analyzing metallocene complexes with organic ligand coordination.

Hydrogen Storage Materials: Promising Materials for Kazakhstan’s Hydrogen Storage Industry

Hydrogen, widely recognized as an efficient and clean energy carrier, holds significant promise for transforming future energy systems. Despite advances in hydrogen production and cost reduction, challenges in hydrogen storage continue to impede its widespread adoption. Traditional storage methods, such as high-pressure tanks and liquid hydrogen, have limitations related to high energy and resource costs. Solid-state materials offer a safer and more reliable alternative for hydrogen storage under various operating conditions. This review article provides an in-depth analysis of hydrogen storage materials, focusing on metal hydrides, complex hydrides, and carbon-based materials, with particular attention to their thermodynamic, structural, and kinetic properties. Additionally, the article explores the potential application of certain materials in Kazakhstan's hydrogen market, highlighting the country's rich mineral resources and existing industrial infrastructure. By leveraging these resources, Kazakhstan can play a crucial role in advancing hydrogen storage technologies and contributing to global decarbonization efforts. The review aims to offer comprehensive insights into the current state and prospects of solid-state hydrogen storage materials, emphasizing their relevance and potential impact on Kazakhstan's energy sector.

Divalent Lanthanide Hydride Complexes

Molecular hydride complexes have attracted recent attention, and divalent lanthanides as central atoms in particular are very interesting. They open up possibilities of combining hydride reactivity and lanthanide reactivity. To date, only Yb(II), Eu(II) and Sm(II) as well as a mixed‐valent Dy(II)/Dy(III) hydride complexes have been isolated and characterised but the known examples are still low in numbers. In this contribution the development of divalent lanthanide chemistry is summarised, and structural features, reactivity patterns in stoichiometric and catalytic reactions as well as spectroscopic details are outlined.

A Paramagnetic Nickel–Zinc Hydride Complex

AbstractReaction of a molecular zinc–hydride [{(ArNCMe)2CH}ZnH] (Ar=2,6‐di‐isopropylphenyl) with 0.5 equiv. of [Ni(CO)Cp]2 led to the isolation of a nickel–zinc hydride complex containing a bridging 3‐centre,2‐electron Ni−H−Zn interaction. This species has been characterized in the solid‐state by single crystal X‐ray diffraction. DFT calculations are consistent with its formulation as a σ‐complex derived from coordination of the zinc–hydride to a paramagnetic nickel(I) fragment. Continuous‐wave and pulse EPR experiments suggest that this species is labile in solution. Further experiments show that in the presence of catalytic quantities of nickel(I) precursors, zinc–hydride bonds can undergo either H/D‐exchange with D2 or dehydrocoupling to form Zn−Zn bonds. In combination, the data support the activation and functionalisation of zinc–hydride bonds at nickel(I) centres.

Protonation of Dppbz- and Binap-Ligated Rhodathiaboranes Yielding Hydron, Hydride, and Hydrogen Exchange.

The reaction of the 11-vertex rhodathiaborane [8,8,8-(H)(PPh3)2-3-(NC5H5)-nido-7,8-RhSB9H10] (1) with 1,2-bis(diphenylphosphine)benzene (dppbz) and (S)-(-)-2,2'-bis(diphenylphosphino)-1,1'-binaphthyl (binap) affords [1,1-(η2-dppbz)-3-(NC5H5)-closo-1,2-RhSB9H8] (2) and [1,1-(η2-binap)-3-(NC5H5)-closo-1,2-RhSB9H8] (3). These 11-vertex closo-rhodathiaborane chelates result from PPh3 ligand substitution at the rhodium center and a nido-to-closo structural cluster transformation driven by H2 loss. Treating compounds 2 and 3 with triflic acid (TfOH) leads to the formation of cationic clusters 4 and 5. The hydrons bind to the polyhedral clusters, acquiring hydride character and providing chemical nonrigidity that manifests through metal vertex-to-thiaborane pseudo-rotations and concomitant hydron tautomerisms. The resulting cations react with hydrogen to form mixtures of hydrons, hydrogen, and hydridorhodathiaboranes in equilibrium. The reaction products are the result of heterolytic cleavage of the H-H bond, with full participation of the clusters and the addition of hydrogen atoms to the cages. In these reactions, there is a conversion of electrons and hydrons into hydrogen, and hydrogen into hydride ligands, demonstrating that these boron-based metal compounds act as electron reservoirs, capable of promoting multielectron processes.

Mechanochemical Synthesis, Characterization and Reactivity of a Room Temperature Stable Calcium Electride.

A new calcium-based Room temperature Stable Electride (RoSE), K[{Ca[N(Mes)(SiMe3)]3(e-)}2K3] (2), is successfully synthesized from the reaction of a calcium tris-amide, [Ca{N(Mes)(SiMe3)}3K] (1) (Mes = 2,4,6-trimethylphenyl), with potassium under mechanochemical treatment. The dimeric structure of K[{Ca[N(Mes)(SiMe3)]3(e-)}2K3] is calculated using ab initio random structure searching (AIRSS) methods. This shows the existence of highly localized anionic electrons (e-) and suggests poor electrical conductance, as confirmed via electroconductivity measurements. The two anionic electrons in 2 are strongly antiferromagnetically coupled, thus in agreement with the largely diamagnetic response from magnetometry. Reaction of 2 with pyridine affords 4,4'-bipyridine, while reaction with benzene gives C-H activation and formation of a calcium hydride complex, [K(η6-C6H6)4][{Ca[N(Mes)(SiMe3)](H)}2K3] (3). Computational DFT analysis reveals the crucial role played by the ligand framework in the stabilization of this new Ca-hydride complex.

Unsymmetric Ir2 and RhIr Dinuclear Complexes Supported by a Linear Tetraphosphine meso-dpmppp, Showing High Reactivity for O2, H2, and HCl.

Unsymmetric dinuclear Ir(I) complexes, [Ir2Cl2(L)(meso-dpmppp)] (L = XylNC (1aIr2), tBuNC (1bIr2), CO (1cIr2)), were synthesized using meso-Ph2PCH2P(Ph)(CH2)3P(Ph)CH2PPh2 (meso-dpmppp), which supports cis-P,P (M1) and trans-P,P (M2) metal sites, and exhibited high reactivity for O2, H2, and HCl. The IrRh heterodinuclear complexes, [M1M2Cl2(L)(meso-dpmppp)] (1xM1M2) (M1M2 = IrRh, RhIr; L = XylNC, CO (x = a, c)), were also synthesized and used together with the Rh2 complexes (1a,cRh2) to elucidate the role of each metal site. For the reactions of O2, 1aIr2 and 1aRhIr showed higher reactivity than those of 1aIrRh and 1aRh2, giving η2-peroxide complexes [{M1Cl2}{M2(η2-O2)(XylNC)}(meso-dpmppp)] (2aIr2, 2aRhIr), from which O2 would not dissociate. All the CO complexes 1cM1M2 (M1, M2 = Ir or Rh) showed no reactivity for O2. In the reactions with H2, 1aIr2 reacted with H2 to give the dihydride complex, [{IrCl2}{Ir(H)2L}(meso-dpmppp)] (11aIr2) and the tetrahydride complex, [{Ir(H)Cl2}(μ-H){Ir(H)2L}(meso-dpmppp)] (12aIr2), while 1aRhIr gave the dihydride complex, and 1aIrRh and 1aRh2 gave no hydride complexes. Reactions of 1a,cM1M2 with HCl afforded the dihydride complexes, [{IrCl3}(μ-H){Ir(H)Cl(XylNC)}(meso-dpmppp)] (14aIr2), [{Ir(H)Cl2}(μ-H){M2Cl2(L)}(meso-dpmppp)] (M2 = Ir, L = CO (15cIr2); M2 = Rh, L = XylNC (15aIrRh), CO (15cIrRh)), and [{Rh(H)Cl2}(μ-Cl){Ir(H)Cl(XylNC)}(meso-dpmppp)] (18aRhIr), the structures varying depending on M1 and M2 as well as L.

Mechanistic Investigation into Copper(I) Hydride Catalyzed Formic Acid Dehydrogenation.

Copper(I) hydride complexes are typically known to react with CO2 to form their corresponding copper formate counterparts. However, recently it has been observed that some multinuclear copper hydrides can feature the opposite reactivity and catalyze the dehydrogenation of formic acid. Here we report the use of a multinuclear PNNP copper hydride complex as an active (pre)catalyst for this reaction. Mechanistic investigations provide insights into the catalyst resting state and the rate-determining step and identify an off-cycle species that is responsible for the unexpected substrate inhibition in this reaction.

Linear Free Energy Relationships Associated with Hydride Transfer From [(6,6'-R2-bpy)Re(CO)3H]: A Cautionary Tale in Identifying Hydrogen Bonding Effects in the Secondary Coordination Sphere.

Six rhenium hydride complexes, [(6,6'-R2-bpy)Re(CO)3H] (bpy = 2,2'-bipyridine, R = OEt, OMe, NHMe, Me, F, Br), were synthesized. These complexes insert CO2 to form rhenium formate complexes of the type [(6,6'-R2-bpy)Re(CO)3{OC(O)H}]. All the rhenium formate species were characterized using X-ray crystallography, which revealed that the bpy ligand is not coplanar with the metal coordination plane containing the two nitrogen donors of the bpy ligand but tilted. A solid-state structure of [(6,6'-Me2-bpy)Re(CO)3H] determined using MicroED also featured a tilted bpy ligand. The kinetics of CO2 insertion into complexes of the type [(6,6'-R2-bpy)Re(CO)3H] were measured experimentally and the thermodynamic hydricities of [(6,6'-R2-bpy)Re(CO)3H] species were determined using theoretical calculations. A Brønsted plot constructed using the experimentally determined rate constants for CO2 insertion and the calculated thermodynamic hydricities for [(6,6'-R2-bpy)Re(CO)3H] revealed a linear free energy relationship (LFER) between thermodynamic and kinetic hydricity. This LFER is different to the previously determined relationship for CO2 insertion into complexes of the type [(4,4'-R2-bpy)Re(CO)3H]. At a given thermodynamic hydricity, CO2 insertion is faster for complexes containing a 6,6'-substituted bpy ligand. This is likely in part due to the tilting observed for systems with 6,6'-substituted bpy ligands. Notably, the 6,6'-(NHMe)2-bpy ligand could in principle stabilize the transition state for CO2 insertion via hydrogen bonding. This work shows that if only the rate of CO2 insertion into [(6,6'-(NHMe)2-bpy)Re(CO)3H] is compared to [(4,4'-R2-bpy)Re(CO)3H] systems, the increase in rate could be easily attributed to hydrogen bonding, but in fact all 6,6'-substituted systems lead to faster than expected rates.

Synthesis of Dinuclear Cobalt Silylene Complexes and Their Catalytic Activity for Alkene Hydrosilylation Reactions.

A novel dinuclear silylene cobalt complex [((Me3P)2Co)(PMe2)(CoCl(PMe3))(Si(NCH2PPh2)2C6H4)] (1) supported by the [PSi(silylene)P] ligand was prepared through the reaction of N-heterocyclic [PSiP] pincer ligand L1 (HSiCl(NCH2PPh2)2C6H4) with Co(PMe3)4. Complex [((Me3P)2Co)2(Si(NCH2PPh2)2C6H4)] (2) was formed through the reaction of complex 1 with MeLi. To the best of our knowledge, complexes 1 and 2 are the first examples of dinuclear silylene cobalt complexes supported by the [PSi(silylene)P] ligand. A new preligand L2 (SiCl2(NCH2PPh2)2C6H4) was synthesized, and the reaction of preligand L2 with Co(PMe3)4 afforded silyl cobalt complex [((Me3P)2Co)(SiCl(NCH2PPh2)2C6H4)] (3). The reaction of 3 with CO delivered cobalt carbonyl complex [((Me3P)(CO)Co)(Si(NCH2PPh2)2C6H4)]2O (4). The catalytic activity of cobalt complexes 1-4 on the hydrosilylation of alkenes was explored. Among the four complexes, complex 1 has the best catalytic activity. The catalytic process could be promoted with NaBHEt3 as an additive, and a complete conversion with an excellent selectivity of 98:2 (b/l) could be reached at 120 °C within 8 min for aryl alkenes. A possible catalytic cycle was proposed on the basis of the experimental results and literature reports, with a cobalt hydride complex as an active intermediate. The molecular structure of complexes 1-4 was determined by single-crystal X-ray diffraction analysis.

Advanced computational screening of X2CaH4 (X = Rb and Cs) for hydrogen storage applications

Utilizing cutting-edge computational screening methods, this study explores the hydrogen storage capacity of two complex metal hydrides, Cs2CaH4 and Rb2CaH4. We perform a thorough analysis of their structural, electrical, optical, and hydrogen storage properties using density functional theory (DFT). Within the I4/mmm space group, both compounds display stable tetragonal crystal structures, and their thermodynamic stability is confirmed by their formation energies. Notably, compared to Rb2CaH4, Cs2CaH4 is more stable. With band gaps of 2.99 eV for Cs2CaH4 and 3.28 eV for Rb2CaH4, the electronic properties show insulating behavior, which is beneficial for reducing electronic interference during hydrogen absorption and desorption. A comparative research reveals that the potential gravimetric hydrogen storage capacities of Cs2CaH4 (1.28%) and Rb2CaH4 (1.86%) are comparable to, albeit marginally less than, those of materials that are frequently explored, such as lithium borohydride. With their individual absorption and reflectivity peaks, the optical characteristics offer more information about how they interact with electromagnetic radiation, information that may be useful for improving their performance in real-world applications. Our results imply that Cs2CaH4and Rb2CaH4 have considerable potential for use in practical hydrogen storage systems, especially in situations where stability and minimal electronic interference are essential. Subsequent research endeavors may concentrate on enhancing the hydrogen storage capacity of these materials, so rendering their incorporation into existing hydrogen storage methods more feasible.

Gold-catalysed amine synthesis by reductive hydroamination of alkynes with nitroarenes.

Amines are the most pivotal class of organic motifs in pharmaceutical compounds. Here we provide a blueprint for a general synthesis of amines by catalyst differentiation enabled by triple Au-H/Au+/Au-H relay catalysis. The parent catalyst is differentiated into a set of catalytically active species to enable triple cascade catalysis, where each catalytic species is specifically tuned for one catalytic cycle. This strategy enables the synthesis of biorelevant amine motifs by reductive hydroamination of alkynes with nitroarenes. Using this triple cascade approach, we have achieved exceptional functional group tolerance, enabling the use of bulk chemical feedstocks as coupling partners for the amination of both simple and complex alkynes (>100 examples), including those derived from pharmaceuticals, peptides and natural products (>30 examples). The isolation and full crystallographic characterization of gold hydride and hydride-bridged gold complexes has garnered insights into the catalyst differentiation process of fundamental organometallic gold hydride complexes.

Facile C[sbnd]H aryl and O[sbnd]H bonds activation at dirhenium site of [Re2(CO)8(THF)2] complex

The activation of small molecules is a topic of great interest and previously we reported on the easy activation of different types of EH bonds at the dinuclear complex [Re2(CO)8(THF)2] (1) where labile THF molecules coordinate to adjacent rhenium(0) atoms. Here we extend the reactivity of 1 reporting on the oxidative addition of benzene and toluene at room temperature to give [Re2(μ-H)(μ-κC-Ar)(CO)8], Ar = −C6H5 (2) and −C6H4Me (3). Compound 3 is a new example of μ-κC-Ar dinuclear rhenium complex and has been obtained as para and meta isomers (3a,b). It is known from the literature that 2 can activate arenes and heteroarenes via reductive elimination of benzene and oxidative addition of CH bonds to the dinuclear fragment. Here we have studied the reaction of 2 with C6D6 and H2CC(H)Ph and determined the kinetic constants by 1H NMR (1.4 × 10−5 s−1 at 308 K and 1.1 × 10−5 s−1 at 298 K, respectively). The results indicate that the rate-determining step of the reaction is the reductive elimination of benzene, while the oxidative addition is fast. Water and methanol react with 1 in toluene at room temperature to give the hydroxo and methoxo hydrido complexes [Re2(μ-H)(μ-OR)(CO)8], RH (5) and CH3 (6). On reacting 1 with water in deuterated toluene, and monitoring by 1H/2H NMR, a preferential deuteration of the hydride site to give [Re2(μ-D)(μ-OH)(CO)8] is evidenced. This finding excludes the oxidative addition of water on the dinuclear “Re2(CO)8” fragment while supporting a heterolytic addition of water via protonation at the µ-κC-tolyl group, elimination of toluene and addition of OH−. Single crystal X-ray diffraction analyses have been performed for complexes 3a, 5 and 6 and their solid state structures have been determined. In particular, the crystal structure of 5 results in a new polymorphic form (5b) and it is discussed in comparison with the already known one (5a).

Flash Communication: Rhodium Complexes of Acetamide-Derived PAlP Pincer.

The new alane/bis(phosphine) PAlP pincer-type ligands 2-Me and 2-Et have been prepared by protolysis reactions of N-(diisopropylphoshino)acetamide with Me3Al or Et3Al in a 2:1 ratio. Upon reaction with a "RhCl" source and pyridine, 2-Me gave rise to a (PAlP)RhMe(py) compound (4-Me), while 2-Et led to the analogous hydride complex (PAlP)RhH(py) (4-H), with a migration of the chloride from Rh to Al. 4-Me and 4-H possess the shortest Rh-Al bonds to date.

N[sbnd]O bond cleavage and N2 activation reactions of the Nitrosyl-Bridged complex [Mo2Cp2(µ-PtBu2)(µ-NO)(NO)2]

The title compound was prepared through a three-step procedure starting with the hydride complex [Mo2Cp2(µ-H)(µ-PtBu2)(CO)4], which was first dehydrogenated through reaction with HBF4·OEt2 to give the unsaturated complex [Mo2Cp2(µ-PtBu2)(CO)4](BF4) (Mo=Mo), which displays a transoid structure according to experimental (Mo-Mo = 2.8283(7) Å) and Density Functional Theory studies. The latter was then reacted with NO to give the dinitrosyl derivative [Mo2Cp2(µ-PtBu2)(CO)2(NO)2](BF4), which in turn was further decarbonylated and nitrosylated upon reaction with [N(PPh3)2]NO2 to give the title nitrosyl-bridged complex (Mo-Mo = 2.905(1) Å). This complex displayed a structure comparable to that of its PCy2-bridged analogue, with similar pyramidalization of the bridging nitrosyl, but a more pronounced folding of the central MoPMoN skeleton and bending of terminal nitrosyls. It also displayed a similar NO bond activation chemistry, as shown by its reactions with HBF4·OEt2 to give the nitroxyl-bridged complex [Mo2Cp2(µ-PtBu2)(µ-k1:η2-HNO)(NO)2](BF4) (HNO = 1.330(8) Å), with P(OEt)3 to give the phosphoraniminate-bridged complex [Mo2Cp2(µ-PtBu2){µ-NP(OEt)3}(NO)2], and with Na(Hg) to give the amide-bridged derivative [Mo2Cp2(µ-PtBu2)(µ-NH2)(NO)2]. Under a nitrogen atmosphere, however, the latter reaction also gave a minor side product identified as the dinitrogen-bridged derivative [Mo4Cp4(µ-PtBu2)2(µ4-N2)(NO)4]. This tetranuclear complex displays a dinitrogen molecule bridging four metal atoms in the novel µ4-k1:k1:k1:k1 coordination mode, with strong metal-nitrogen interactions taking the N2 ligand to the diazendiide (N22-) limit (NN = 1.241(3) Å).

Challenges in developing materials for microreactors: A case-study of yttrium dihydride in extreme conditions

The development of microreactor technology presents an efficient solution for providing portable electricity, catering to both human space exploration needs within our solar system and supplying power to remote Earth-bound areas. The miniaturization of nuclear reactors poses immediate new challenges for materials science with respect to the capability for controlling nuclear reactions via thermalization of highly-energetic neutrons. In a microreactor, neutron moderation takes place in compact geometries, thus new moderator materials are required to exhibit high moderating power per unit of volume. This challenge is currently being addressed through the development of transition metal hydrides, known for their strong nuclear moderation capability but to date, research on their irradiation response is limited, specifically regarding phase stability, hydrogen in-lattice retention, and their dependence on irradiation temperature and dose. Herein, we present a detailed investigation on the response of yttrium dihydride (YH2) to heavy ion irradiation. The experiments indicate that YH2 is stable up to an irradiation dose of 2 dpa and below 800°C, identified herein as a critical temperature for YH2. Our study detected the nucleation and growth of voids as a function of the irradiation temperature. They were the predominant type of radiation damage present in the microstructure of YH2 that was distinguishable from pre-existing defects in the pristine YH2 samples. Below the critical temperature, no phase transformation (degassing/dehydriding) nor amorphization occurred. Experimental results with concomitant density functional theory calculations allowed us to elaborate and propose new strategies to enhance the metal hydride performance in extreme environments.

Electron-Poor Iridium Pincer Complexes as Dehydrogenation Catalysts: Investigations into Deactivation through Formation of N2, CO, and Hydride Complexes

Electron-Poor Iridium Pincer Complexes as Dehydrogenation Catalysts: Investigations into Deactivation through Formation of N₂, CO, and Hydride Complexes

Molecular hydrogen in the N-doped LuH3 system as a possible path to superconductivity

The discovery of ambient superconductivity would mark an epochal breakthrough long-awaited for over a century, potentially ushering in unprecedented scientific and technological advancements. The recent findings on high-temperature superconducting phases in various hydrides under high pressure have ignited optimism, suggesting that the realization of near-ambient superconductivity might be on the horizon. However, the preparation of hydride samples tends to promote the emergence of various metastable phases, marked by a low level of experimental reproducibility. Identifying these phases through theoretical and computational methods entails formidable challenges, often resulting in controversial outcomes. In this paper, we consider N-doped LuH3 as a prototypical complex hydride: By means of machine-learning-accelerated force-field molecular dynamics, we have identified the formation of H2 molecules stabilized at ambient pressure by nitrogen impurities. Importantly, we demonstrate that this molecular phase plays a pivotal role in the emergence of a dynamically stable, low-temperature, experimental-ambient-pressure superconductivity. The potential to stabilize hydrogen in molecular form through chemical doping opens up a novel avenue for investigating disordered phases in hydrides and their transport properties under near-ambient conditions.

Chromium Complexes with Benzanellated N-Heterocyclic Phosphenium Ligands-Synthesis, Reactivity and Application in Catalytic CO2 Reduction.

A chromium complex carrying two benzanellated N-heterocyclic phosphenium (bzNHP) ligands was prepared by a salt metathesis approach. Spectroscopic studies suggest that the anellation enhances the π-acceptor ability of the NHP-units, which is confirmed by the facile electrochemical reduction of the complex to a spectroscopically characterized radical anion. Co-photolysis with H2 allowed extensive conversion into a σ-H2-complex, which shows a diverse reactivity towards donors and isomerizes under H-H bond fission and shift of a hydride to a P-ligand. The product carrying phosphenium, phosphine and hydride ligands was also synthesized independently and reacts reversibly with CO and MeCN to yield bis-phosphine complexes under concomitant Cr-to-P-shift of a hydride. In contrast, CO2 was not only bound but reduced to give an isolable formato complex, which reacted with ammonia borane under partial recovery of the metal hydride and production of formate. Further elaboration of the reactions of the chromium complexes with CO2 and NH3BH3 allowed to demonstrate the feasibility of a Cr-catalyzed transfer hydrogenation of CO2 to methanol. The various complexes described were characterized spectroscopically and in several cases by XRD studies. Further insights in reactivity patterns were provided through (spectro)electrochemical studies and DFT calculations.

A Paramagnetic Nickel-Zinc Hydride Complex.

Reaction of a molecular zinc-hydride [{(ArNCMe)2CH}ZnH] (Ar = 2,6-di-isopropylphenyl) with 0.5 equiv. of [Ni(CO)Cp]2 led to the isolation of a nickel-zinc hydride complex containing a bridging 3-centre,2-electron Ni-H-Zn interaction. This species has been characterized in the solid-state by single crystal X-ray diffraction. DFT calculations are consistent with its formulation as a σ-complex derived from coordination of the zinc-hydride to a paramagnetic nickel(I) fragment. Continuous wave and pulse EPR experiments suggest that this species is not stable in solution and suggest that this species is labile in solution. Further experiments show that in the presence of catalytic quantities of nickel(I) precursors, zinc-hydride bonds can undergo either H/D-exchange with D2 or dehydrocoupling to form Zn-Zn bonds. In combination, the data support the activation and functionalisation of zinc-hydride bonds at nickel(I) centres.