Bioreactors for H2 Production by Purple Nonsulfur Bacteria

Two types of laboratory-scale bioreactors were designed for H₂ production by purple nonsulfur bacteria. The bioreactors employed a unique type of hydrogenase activity found in some photosynthetic bacteria that functions in darkness to shift CO (and H₂O) into H₂ (and CO₂). The mass transport of gaseous CO into an aqueous bacterial suspension was the rate-limiting step and the main challenge for bioreactor design. Hollow-fiber and bubble-train bioreactors employing immobilized and free-living bacteria have proven effective for enhancing the mass transfer of CO. The hollow-fiber bioreactor was designed so that both a growth medium and CO (10% in N₂) passed from the inside of the fibers to the outside within the bioreactor. Bacteria were immobilized on the outer surface of the hollow fibers. Hydrogen production from CO at an average rate of 125 ml g cdw⁻¹ h⁻¹ (maximum rate of 700 ml g cdw⁻¹ h⁻¹) was observed for more than 8 months. The bubble-train bioreactor was built using polyvinyl chloride (PVC) tubing, wound helically on a vertical cylindrical supporting structure. Small bubbles containing CO were injected continuously through a needle/septum connection from the gas reservoir (20% CO). Up to 140 ml g cdw⁻¹ h⁻¹ of H₂ production activity was observed using this bioreactor for more than 10 days. Dr. Paul Weaver is deceased.     

Diminished Respirative Growth and Enhanced Assimilative Sugar Uptake Result in Higher Specific Fermentation Rates by the MutantPichia stipitis FPL-061

A mutant strain ofPichia stipitis, FPL-061, was obtained by selecting for growth on L-xylose in the presence of respiratory inhibitors. The specific fermentation rate of FPL-061, was higher than that of the parent,Pichia stipitis CBS 6054, because of its lower cell yield and growth rate and higher specific substrate uptake rate. With a mixture of glucose and xylose, the mutant strain FPL-061 produced 29.4 g ethanol/L with a yield of 0.42 g ethanol/g sugar consumed. By comparison, CBS 6054 produced 25.7 g ethanol/L with a yield of 0.35 gJg. The fermentation was most efficient at an aeration rate of 9.2 mmoles O₂ L^-1 h^-1. At high aeration rates (22 mmoles O₂ L^-1 h^-1), the mutant cell yield was less than that of the parent. At low aeration rates, (1.1 to 2.5 O₂ L^-1 h^-1), cell yields were similar, the ethanol formation rates were low, and xylitol accumulation was observed in both the strains. Both strains respired the ethanol once sugar was exhausted. We infer from the results that the mutant, P.stipitis FPL-061, diverts a larger fraction of its metabolic energy from cell growth into ethanol production.     

Stabilization of highly reactive cyclic polyolefins by coordination to iron carbonyls: cis-cyclononatetraene-iron tricarbonyl

Reaction of cis-bicyclo[6.1.0]nona-2,4,6-triene (C₉H₁₀) (I) with Fe₂(CO)₉, at room temperature, yields a number of complexes (IV)–(IX). One of the e, (IX), is the Fe₂(CO)₆ derivative of the starting polyolefin (I), whereas the others are Fe(CO)₃ or Fe(CO)₄ complexes of isomeric C₉H₁₀ polyolefins.(IV) is (h⁴-l,2,3,4-cis-8,9-dihydroindene)iron tricarbonyl, (V) is tentatively formulated as (h²-or h²-5,6-cis-bicyclo[5.2.0]nona-2,5,8-triene)iron tetracarbonyl, (VI) has been characterized only as C₉H₁₀Fe(CO)₃, and (VII) and (VIII) are the asymmetric and symmetric isomers (h⁴-cis-cyclononatetraene)iron tricarbonyl. Characterization of the complexes has been obtained through PMR, IR, and mass spectra.Peculiar features of this reaction are the promotion of the polyolefin (I) rearrangement by iron carbonyls and the stabilization of highly reactive intermediates through coordination to the metal carbonyl groups. fa]Work presented in part at the 3rd International Symposium on Reactivity and Bonding in Transition Organometallic Compounds, Venice, September 9–10, 1970.     

Theoretical study of the relative stabilities of H+(X)2 and H+(X)3 conformers and their clustering energies: X  CO and N2

Third-order Møller–Plesset perturbation theory (MP 3) with a 6-31G** basis set was applied to study the relative stabilities of H⁺(X)₂ conformations (X ? CO and N₂) and their clustering energies. The effect of both basis set extensions and electron correlation is not negligible on the relative stabilities of the H⁺(CO)₂ clusters. The most stable conformation of H⁺(CO)₂ is found to be a C_∞v structure in which a carbon atom of CO bonds to the proton of H⁺(CO), whereas that of H⁺(N₂)₂ is a symmetry D_∞h structure. The second lowest energy conformations of H⁺(CO)₂ and H⁺(N₂)₂ lie within 2 kcal/mol above the energies of the most stable structures. Clustering energies computed using MP 3 method with the 6-31G** basis set are in good agreement with the experimental findings of Hiraoka, Saluja, and Kebarle. The low-lying singlet conformations of H⁺(X)₃ (X ? CO and N₂) have been studied by the use of the Hartree–Fock MO method with the 6-31G** basis set and second-order Møller–Plesset perturbation theory with a 4-31G basis set. The most stable structure is a T-shaped structure in which a carbon atom of CO (or a nitrogen atom of N₂) attacks the proton of the most stable conformation of H⁺(X)₂ clusters.     

预处理对Ni-Co双金属沼气重整催化剂性能与结构的影响

采用过量浸渍法制备了Ni-Co/La₂O₃-γ-Al₂O₃双金属催化剂, 并使用固定床石英反应器在850℃,0.1MPa和空速为6000mL g_cat^-1 h^-1的条件下考察了预处理对催化剂性能的影响. 运用X射线衍射、热重-差示扫描量热、透射电子显微镜、扫描电镜和X射线能谱分析等手段对催化剂进行了表征. 结果表明,与传统氢气还原预处理相比,经氢气和二氧化碳预处理后, 催化剂性能明显提高,且能基本消除该催化剂上沼气重整反应的诱导期. 511 h的稳定性实验结果表明,催化剂经氢气和二氧化碳预处理后具有很好的稳定性和抗积碳性,平均积碳速率仅为0.2 mg g_cat^-1 h^-1. 表征结果显示,经氢气和二氧化碳预处理后,催化剂具有更好的抗烧结和抗积碳性能,反应后金属颗粒较小,分布较均匀,粒径分布范围较窄,从而增强了催化剂的稳定性.     

High‐Rate,Tunable Syngas Production with Artificial Photosynthetic Cells

An artificial photosynthetic (APS) system consisting of a photoanodic semiconductor that harvests solar photons to split H₂O, a Ni‐SNG cathodic catalyst for the dark reaction of CO₂ reduction in a CO₂‐saturated NaHCO₃ solution, and a proton‐conducting membrane enabled syngas production from CO₂ and H₂O with solar‐to‐syngas energy‐conversion efficiency of up to 13.6 %. The syngas CO/H₂ ratio was tunable between 1:2 and 5:1. Integration of the APS system with photovoltaic cells led to an impressive overall quantum efficiency of 6.29 % for syngas production. The largest turnover frequency of 529.5 h^?1 was recorded with a photoanodic N‐TiO₂ nanorod array for highly stable CO production. The CO‐evolution rate reached a maximum of 154.9 mmol g^?1 h^?1 in the dark compartment of the APS cell. Scanning electrochemical–atomic force microscopy showed the localization of electrons on the single‐nickel‐atom sites of the Ni‐SNG catalyst, thus confirming that the multielectron reduction of CO₂ to CO was kinetically favored.     

High‐Rate,Tunable Syngas Production with Artificial Photosynthetic Cells

An artificial photosynthetic (APS) system consisting of a photoanodic semiconductor that harvests solar photons to split H₂O, a Ni‐SNG cathodic catalyst for the dark reaction of CO₂ reduction in a CO₂‐saturated NaHCO₃ solution, and a proton‐conducting membrane enabled syngas production from CO₂ and H₂O with solar‐to‐syngas energy‐conversion efficiency of up to 13.6 %. The syngas CO/H₂ ratio was tunable between 1:2 and 5:1. Integration of the APS system with photovoltaic cells led to an impressive overall quantum efficiency of 6.29 % for syngas production. The largest turnover frequency of 529.5 h^?1 was recorded with a photoanodic N‐TiO₂ nanorod array for highly stable CO production. The CO‐evolution rate reached a maximum of 154.9 mmol g^?1 h^?1 in the dark compartment of the APS cell. Scanning electrochemical–atomic force microscopy showed the localization of electrons on the single‐nickel‐atom sites of the Ni‐SNG catalyst, thus confirming that the multielectron reduction of CO₂ to CO was kinetically favored.     

The stereospecificity at the iron center of the decarbonylation of an ironacetyl complex

The dinuclear complex [(h⁵-1-CH₃-3-C₆H₅C₅H₃)Fe(CO)₂]₂ was synthesized by reaction of Fe₂(CO)9 with 1-methyl-3-phenylcyclopentadiene; it was converted to (h⁵-1-CH₃-3-C₆H₅C₅H₃)Fe(CO)₂CH₃ by reduction with sodium amalgam and addition of CH₃l, and thence to (h⁵-1-CH₃-3-C₆H₅C₅H₃)Fe(CO)[P(C₆H₅)₃] (COCH₃) (I) by reaction with P(C₆H₅)₃. The acetyl I was separated into two diastereomerically related pairs of enantiomers. Ia and Ib, by a combination of column chromatography on alumina and crystallization from benzene/pentane. The photochemical decarbonylation of Ia and Ib in benzene or THF solution was examined by ¹H NMR spectroscopy. This reaction proceeds with high stereospecificity (>84% retention or inversion) at the iron center to yield (h⁵-1-CH₃-3-C₆H₈C₅H₃)Fe(CO)[P(C₆H₅)₃]CH₃(II), enriched in the diastereomerically related pairs of enantiomers, IIa and IIb, respectively. Since IIa and IIb epimerize under the photolytic conditions of decarbonylation, the actual stereospecificity of the conversion of I to II is higher than 84%, and likely 100%. This is supported by the data from kinetic studies of the decarbonylation of I and the epimerization of II, carried out under identical photolytic conditions. The implications of the foregoing results to the mechanism of the decarbonylation are considered. Also described herein is the synthesis of other complexes with two asymmetric centers of the general formula (h⁵-cyclopentadienyl)Fe(CO)(L)(COR) and (h⁵-cyclopentadienyl)Fe(CO)(L)R that contain either an unsymmetrically substituted h⁵-cyclopentadienyl ring or a chiral tertiary phosphine.     

Xantphite: A New Family of Ligands for Catalysis. Applications in the Hydroformylation of Alkenes

The novel bulky diphosphite (P∩P) ligands ( 3 and 4 ) based on the 2,7,9,9‐tetramethyl‐9H‐xanthene‐4,5‐diol ( 2 ) backbone were investigated in the Rh‐catalyzed hydroformylation of oct‐1‐ene, styrene, and (E)‐oct‐2‐ene. These diphosphites gave rise to very active and selective catalysts for the hydroformylation of oct‐1‐ene to nonanal with average rates>10000 (mol aldehyde)(mol Rh)⁻¹h⁻¹ (P(CO/H₂)=20 bar, T=80°, [Rh]=1 mM ) and maximum selectivities of 79% for the linear product. Relatively high selectivities towards the linear aldehyde (up to 70%, linear/branched up to 2.3) but very high activities (up to 39000 (mol aldehyde)(mol Rh)⁻¹h⁻¹) were observed for the hydroformylation of styrene in the presence of these bidentate ligands (P(CO/H₂)=2 – 10 bar, T=120°, [Rh]=0.2 mM ). Remarkable activities (up to 980 (mol aldehyde)(mol Rh)⁻¹h⁻¹) were achieved with these diphosphites for the hydroformylation of (E)‐oct‐2‐ene with selectivities for the linear product of 74% (l/b up to 2.8, P(CO/H₂)=2 bar, T=120°, [Rh]=1 mM ). A detailed study of the solution structure of the catalyst under catalytic conditions was performed by NMR and high‐pressure FT‐IR. The spectroscopic data revealed that under hydroformylation conditions, the bidentate ligands rapidly formed stable, well‐defined catalysts with the structure [RhH(CO)₂(P∩P)]. All the ligands showed a preference for an equatorial‐apical ( ea ) coordination mode in the trigonal bipyramidal Rh‐complexes, indicating that a bis‐equatorial ( ee ) coordination is not a prerequisite for highly selective catalysts.     

Benzocyclobutenylidene-h5-cyclopentadienyldicarbonyl-iron(II). A hydride abstractor more specific than the triphenylcarbenium ion

Benzocyclobutenylidene-h⁵-cyclopentadienyldicarbonyliron(II) hexafluorophosphate converts h⁵-CpFe(CO)₂R (R = cyclo-C₃H₅, CH₂-cyclo-C₃H₅) to the respective allene and butadiene complexes whereas Ph₃C⁺ primarily yields addition products; both carbenium ions add to h¹- allyl- and substituted h¹ -allyl-iron complexes with the exception of the 3,3-dimethylpropenyl complex which is converted in both cases to h⁵-CpFe(CO)₂(CH₂CHCMeCH₂)⁺.     

Syntheses and crystal structures of new mononuclear and binuclear ruthenium complexes supported by salicylaldimine ligands

Treatment of Ru₃(CO)₁₂ with salicylaldimines [2-HOC₆H₄-CH?=N–C₆H₄-4-R] [R?=?Me; Cl; Br; OMe; CF₃] in refluxing toluene gave three novel binuclear ruthenium carbonyl complexes {[µ-?²-2-OC₆H₄-CH=N-C₆H₄-4-R)][µ-?²-2-CH₂-OC₆H₄][µ-?-NH-C₆H₄-4-R]}Ru₂(CO)₄ [R?=?Me (1), Cl (2), Br (3)] and three mononuclear carbonyl complexes [2-OC₆H₄-CH=N-C₆H₄-4-R][2-OC₆H₄-CH₂NH-C₆H₄-4-R]Ru(CO)₂ [R?=?Me (4), OMe (5), CF₃ (6)], respectively. The structures of 1–6 were fully characterized using IR and NMR spectroscopy, elemental analysis and single-crystal X-ray diffraction. These results suggest that the substituent group on the phenyl of salicylaldimine has a significant effect on the structure of the Ru complex.

     

Tweaking Photo CO2 Reduction by Altering Lewis Acidic Sites in Metalated-Porous Organic Polymer for Adjustable H2/CO Ratio in Syngas Production

Herein, we have specifically designed two metalated porous organic polymers ( Zn-POP and Co-POP ) for syngas (CO+H₂) production from gaseous CO₂. The variable H₂/CO ratio of syngas with the highest efficiency was produced in water medium (without an organic hole scavenger and photosensitizer) by utilizing the basic principle of Lewis acid/base chemistry. Also, we observed the formation of entirely different major products during photocatalytic CO₂ reduction and water splitting with the help of the two catalysts, where CO (145.65 μmol g⁻¹ h⁻¹) and H₂ (434.7 μmol g⁻¹ h⁻¹) production were preferentially obtained over Co-POP & Zn-POP , respectively. The higher electron density/better Lewis basic nature of Co-POP was investigated further using XPS, XANES, and NH₃-TPD studies, which considerably improve CO₂ activation capacity. Moreover, the structure–activity relationship was confirmed via in situ DRIFTS and DFT studies, which demonstrated the formation of COOH* intermediate along with the thermodynamic feasibility of CO₂ reduction over Co-POP while water splitting occurred preferentially over Zn-POP .     

Computationally Designed Families of Flat,Tubular, and Cage Molecules Assembled with “Starbenzene” Building Blocks through Hydrogen‐Bridge Bonds

Using density functional calculations, we demonstrate that the planarity of the nonclassical planar tetracoordinate carbon (ptC) arrangement can be utilized to construct new families of flat, tubular, and cage molecules which are geometrically akin to graphenes, carbon nanotubes, and fullerenes but have fundamentally different chemical bonds. These molecules are assembled with a single type of hexagonal blocks called starbenzene (D_6h C₆Be₆H₆) through hydrogen‐bridge bonds that have an average bonding energy of 25.4–33.1 kcal mol^?1. Starbenzene is an aromatic molecule with six π electrons, but its carbon atoms prefer ptC arrangements rather than the planar trigonal sp² arrangements like those in benzene. Various stability assessments indicate their excellent stabilities for experimental realization. For example, one starbenzene unit in an infinite two‐dimensional molecular sheet lies on average 154.1 kcal mol^?1 below three isolated linear C₂Be₂H₂ (global minimum) monomers. This value is close to the energy lowering of 157.4 kcal mol^?1 of benzene relative to three acetylene molecules. The ptC bonding in starbenzene can be extended to give new series of starlike monocyclic aromatic molecules (D_4h C₄Be₄H₄^2?, D_5h C₅Be₅H₅^?, D_6h C₆Be₆H₆, D_7h C₇Be₇H₇⁺, D_8h C₈Be₈H₈^2?, and D_9h C₉Be₉H₉^?), known as starenes. The starene isomers with classical trigonal carbon sp² bonding are all less stable than the corresponding starlike starenes. Similarly, lithiated C₅Be₅H₅ can be assembled into a C₆₀‐like molecule. The chemical bonding involved in the title molecules includes aromaticity, ptC arrangements, hydrogen‐bridge bonds, ionic bonds, and covalent bonds, which, along with their unique geometric features, may result in new applications.     

CO2预处理操作条件对Ni-Co双金属催化剂性能与结构的影响

与传统H₂预处理方法相比,新型H₂+CO₂预处理方法（HCD）能显著提升Ni-Co双金属催化剂的沼气重整活性及抗积碳性能. 考察了HCD预处理操作条件对催化剂性能与结构的影响. 较好的HCD预处理操作条件是在催化剂经H₂处理之后,再用175-200 mL·min^-1的原料气CH₄/CO₂（比例为0：10）在780-800 ℃下还原0.5-1h. 在优化预处理操作条件下对催化剂进行了511 h的耐久性考察,并运用X射线衍射（XRD）、热重-差示扫描量热（TG-DSC）、透射电子显微镜（TEM）等手段对耐久性测试后的催化剂进行了表征. 在511 h 的稳定性实验内,CH₄、CO₂转化率,H₂、CO选择性及H₂/CO体积比分别高达96%、97%,98%、99%及0.98. 催化剂在测试期间的平均积碳速率仅为0.2 mg·g^-1·h^-1. 在该预处理操作参数下,催化剂拥有最好的综合性能和良好的耐久性.     

Synthesis and Reactivity of Organometallic Intermediates Relevant to Cobalt-Catalyzed Hydroformylation

Intermediates relevant to cobalt-catalyzed alkene hydroformylation have been isolated and evaluated in fundamental organometallic transformations relevant to aldehyde formation. The 18-electron (R,R)-(^iPrDuPhos)Co(CO)₂H has been structurally characterized, and it promotes exclusive hydrogenation of styrene in the presence of 50 bar of H₂/CO gas (1:1) at 100 °C. Deuterium-labeling studies established reversible 2,1-insertion of styrene into the Co−D bond of (R,R)-(^iPrDuPhos)Co(CO)₂D. Whereas rapid β-hydrogen elimination from cobalt alkyls occurred under an N₂ atmosphere, alkylation of (R,R)-(^iPrDuPhos)Co(CO)₂Cl in the presence of CO enabled the interception of (R,R)-(^iPrDuPhos)Co(CO)₂C(O)CH₂CH₂Ph, which upon hydrogenolysis under 4 atm H₂ produced the corresponding aldehyde and cobalt hydride, demonstrating the feasibility of elementary steps in hydroformylation. Both the hydride and chloride derivatives, (X=H⁻, Cl⁻), underwent exchange with free ¹³CO. Under reduced pressure, (R,R)-(^iPrDuPhos)Co(CO)₂Cl underwent CO dissociation to form (R,R)-(^iPrDuPhos)Co(CO)Cl.     

Intermediates in the intramolecular ligand transfer reactions of h5-C5H5Fe(CO)2R complexes

Dissolution of h⁵-C₅H₅Fe(CO)₂R (I) (R = cyclohexyl or cyclohexylmethyl) in DMSO leads to the formation of a solvent coordinated acyl complex, h⁵-C₅H₅Fe(CO)(COR)(DMSO) (II). Treatment of this complex with triphenylphosphine leads to its conversion to h⁵-C₅H₅Fe(COR)(PPh₃) (III). Rates for the reaction I ? and II → III have been determined. A comparison of the rates of the reaction I → III in eight solvents shows no specific rate acceleration in DMSO and no correlation with solvent donicity. The results are in accord with a two step mechanism in which the first intermediate is the coordiantively-unsaturated species h⁵-C₅H₅Fe(COR)(CO). The small spread in rates for solvents of widely different dielectric constants suggests little charge separation in the transition state for this step.     

Selective oxidation of CO in excess hydrogen on copper—cerium-containing catalysts

Selective oxidation of CO that is in mixtures enriched in H₂ was studied to investigate catalytic properties of the 0.5—80% CuO/Ce_0.7Zr_0.3O₂ system. The catalysts were prepared by the combined decomposition of copper, cerium, and zirconyl nitrates at 300 °C. The systems studied are active and stable under mild conditions of the process (80—160 °C) and at high space velocities (to 100000 h^–1) of the reaction mixture (2% CO, 1% O₂, 40—50% H₂). With an increase in the CuO content in the catalysts up to 20%, the degree of CO removal achieves 60% (120 °C and V = 35000 h^–1) and further does not change appreciably. The contribution of oxygen participation into CO oxidation is virtually independent of the copper concentration in the sample and ranges from 65 to 75%. The dependences of the Arrhenius equation parameters for CO and H₂ oxidation on the catalyst composition were determined, which makes it possible to calculate the conversion of reactants and selectivity of CO conversion under the specified conditions of the process. The addition of CO₂ and H₂O (12—15%) to the reaction mixture decreases the catalyst activity and simultaneously increases the selectivity of CO oxidation to 100%. It is shown by the TPR and X-ray diffraction methods that the combined decomposition of the starting Cu²⁺, Ce³⁺, and ZrO²⁺ nitrates produces solid solutions of oxides with a high content of CuO. The reductive pre-treatment of fresh samples of the studied catalysts results in the destruction of the solid solution and formation of highly dispersed Cu particles on the surface of Ce—Zr—O. These particles are active in CO oxidation.     

The effect of basis set superposition error on the convergence of interaction energies

 For the intermolecular interaction energies of ion-water clusters [OH⁻(H₂O) _n (n=1,2), F⁻(H₂O), Cl⁻(H₂O), H₃O⁺(H₂O) _n (n=1,2), and NH₄ ⁺(H₂O) _n (n=1,2)] calculated with correlation-consistent basis sets at MP2, MP4, QCISD(T), and CCSD(T) levels, the basis set superposition error is nearly zero in the complete basis set (CBS) limit. That is, the counterpoise-uncorrected intermolecular interaction energies are nearly equal to the counterpoise-corrected intermolecular interaction energies in the CBS limit. When the basis set is smaller, the counterpoise-uncorrected intermolecular interaction energies are more reliable than the counterpoise-corrected intermolecular interaction energies. The counterpoise-uncorrected intermolecular interaction energies evaluated using the MP2/aug-cc-pVDZ level is reliable. Received: 14 March 2001 / Accepted: 25 April 2001 / Published online: 9 August 2001     

Condensation reactions of indole with acetophenones affording mixtures of 3,3-(1-phenylethane-1,1-diyl)bis(1H-indoles) and 1,2,3,4-tetrahydro-3-(1H-indol-3-yl)-1-methyl-1,3-diphenylcyclopent[b]indoles

Condensation of indole 1a with eight acetophenones 8a–h in ethanolic HCl afforded the corresponding mixtures of condensation products: 3,3-(1-phenylethane-1,1-diyl)bis(1H-indoles) 11a–h (2:1 condensation of indole:acetophenone, –H₂O) and diastereomers of substituted 1,2,3,4-tetrahydro-3-(1H-indol-3-yl)-1-methyl-1,3-diphenylcyclopent[b]indoles 12a–h and 13a–h (2:2 condensation of indole:acetophenone, –2H₂O). Each mixture was analyzed by ¹H NMR. The use of substituted electron-withdrawing acetophenones favored formation of 2:1 condensation products, whereas the use of substituted electron-donating acetophenones favored formation of 2:2 condensation products. Increased reaction temperature gave higher 2:2 condensation yields, but temperatures above 40?°C were unfavorable, giving complex, tarry mixtures.     

Highly Active,Low‐Valence Molybdenum‐ and Tungsten‐Amide Catalysts for Bifunctional Imine‐Hydrogenation Reactions

The reactions of [M(NO)(CO)₄(ClAlCl₃)] (M=Mo, W) with (iPr₂PCH₂CH₂)₂NH, (PN^HP) at 90 °C afforded [M(NO)(CO)(PN^HP)Cl] complexes (M=Mo, 1a ; W, 1b ). The treatment of compound 1a with KOtBu as a base at room temperature yielded the alkoxide complex [Mo(NO)(CO)(PN^HP)(OtBu)] ( 2a ). In contrast, with the amide base Na[N(SiMe₃)₂], the PN^HP ligand moieties in compounds 1a and 1b could be deprotonated at room temperature, thereby inducing dehydrochlorination into amido complexes [M(NO)(CO)(PNP)] (M=Mo, 3a ; W, 3b ; PNP=(iPr₂PCH₂CH₂)₂N)). Compounds 3a and 3b have pseudo‐trigonal‐bipyramidal geometries, in which the amido nitrogen atom is in the equatorial plane. At room temperature, compounds 3a and 3b were capable of adding dihydrogen, with heterolytic splitting, thereby forming pairs of isomeric amine‐hydride complexes [Mo(NO)(CO)H(PN^HP)] ( 4a(cis) and 4a(trans) ) and [W(NO)(CO)H(PN^HP)] ( 4b(cis) and 4b(trans) ; cis and trans correspond to the position of the H and NO groups). H₂ approaches the Mo/W?N bond in compounds 3a , 3b from either the CO‐ligand side or from the NO‐ligand side. Compounds 4a(cis) and 4a(trans) were only found to be stable under a H₂ atmosphere and could not be isolated. At 140 °C and 60 bar H₂, compounds 3a and 3b catalyzed the hydrogenation of imines, thereby showing maximum turnover frequencies (TOFs) of 2912 and 1120 h^?1, respectively, for the hydrogenation of N‐(4 ‐ methoxybenzylidene)aniline. A Hammett plot for various para‐substituted imines revealed linear correlations with a negative slope of ?3.69 for para substitution on the benzylidene side and a positive slope of 0.68 for para substitution on the aniline side. Kinetics analysis revealed the initial rate of the hydrogenation reactions to be first order in c(cat.) and zeroth order in c(imine). Deuterium kinetic isotope effect (DKIE) experiments furnished a low k_H/k_D value (1.28), which supported a Noyori‐type metal–ligand bifunctional mechanism with H₂ addition as the rate‐limiting step.