Metal-organic Reactions Research Articles

R2SCAN-D4: Dispersion corrected meta-generalized gradient approximation for general chemical applications.

We combine a regularized variant of the strongly constrained and appropriately normed semilocal density functional [J. Sun, A. Ruzsinszky, and J. P. Perdew, Phys. Rev. Lett. 115, 036402 (2015)] with the latest generation semi-classical London dispersion correction. The resulting density functional approximation r2SCAN-D4 has the speed of generalized gradient approximations while approaching the accuracy of hybrid functionals for general chemical applications. We demonstrate its numerical robustness in real-life settings and benchmark molecular geometries, general main group and organo-metallic thermochemistry, and non-covalent interactions in supramolecular complexes and molecular crystals. Main group and transition metal bond lengths have errors of just 0.8%, which is competitive with hybrid functionals for main group molecules and outperforms them for transition metal complexes. The weighted mean absolute deviation (WTMAD2) on the large GMTKN55 database of chemical properties is exceptionally small at 7.5 kcal/mol. This also holds for metal organic reactions with an MAD of 3.3 kcal/mol. The versatile applicability to organic and metal-organic systems transfers to condensed systems, where lattice energies of molecular crystals are within the chemical accuracy (errors <1 kcal/mol).

DFT-D4 counterparts of leading meta-generalized-gradient approximation and hybrid density functionals for energetics and geometries.

Previously, we introduced DFT-D3(BJ)ωB97X-V and ωB97M-V functionals and assessed them for the GMTKN55 database [Najibi and Goerigk, J Chem. Theory Comput. 2018, 14, 5725]. In this study, we present DFT-D4 damping parameters to build the DFT-D4 counterparts of these functionals and assess these in comparison. We extend our analysis beyond GMTKN55 and especially turn our attention to enzymatically catalyzed and metal-organic reactions. We find that B97M-D4 is now the second-best performing meta-generalized-gradient approximation functional for the GMTKN55 database and it can provide noticeably better organometallic reaction energies compared to B97M-D3(BJ). Moreover, the aforementioned DFT-D3(BJ)-based functionals have not been thoroughly assessed for geometries and herein we close this gap by analyzing geometries of noncovalently bound dimers and trimers, peptide conformers, water hexamers and transition-metal complexes. We find that several of the B97(M)-based methods-particularly the DFT-D4 versions-surpass the accuracy of previously studied methods for peptide conformer, water hexamer, and transition-metal complex geometries, making them safe-to-use, cost-efficient alternatives to the original methods. The DFT-D4 variants can be easily used with ORCA4.1 and above.

Flexible automation with compact NMR spectroscopy for continuous production of pharmaceuticals

Modular plants using intensified continuous processes represent an appealing concept for the production of pharmaceuticals. It can improve quality, safety, sustainability, and profitability compared to batch processes; besides, it enables plug-and-produce reconfiguration for fast product changes. To facilitate this flexibility by real-time quality control, we developed a solution that can be adapted quickly to new processes and is based on a compact nuclear magnetic resonance (NMR) spectrometer. The NMR sensor is a benchtop device enhanced to the requirements of automated chemical production including robust evaluation of sensor data. Beyond monitoring the product quality, online NMR data was used in a new iterative optimization approach to maximize the plant profit and served as a reliable reference for the calibration of a near-infrared (NIR) spectrometer. The overall approach was demonstrated on a commercial-scale pilot plant using a metal-organic reaction with pharmaceutical relevance.Graphical abstract

Formulation of Small Test Sets Using Large Test Sets for Efficient Assessment of Quantum Chemistry Methods.

In the present study, we have examined in detail literature data of deviations for a wide range of (mainly) DFT methods for the extensive MGCDB82 set (∼4400 data points) of main-group thermochemical quantities. We use the data and standard statistical techniques (lasso regularization and forward selection) to devise the MG8 model for linearly combining assessment results of a collection of small data sets to accurately estimate the MAD of MGCDB82. The MG8 model contains a total of 64 data points representing noncovalent interactions, isomerization energies, thermochemical properties, and barrier heights. It is thus well suited for rapid evaluation of new quantum chemistry procedures. We propose that a value of ∼4 kJ mol-1 for an estimated MAD by the MG8 model (EMADMG8) to be an initial indicator of a highly robust quantum chemistry method, with large deviations occurring mainly for properties (such as heats of formation) that are known to be difficult to accurately compute. For methods with larger EMADs, we emphasize the importance of more thorough testing, as these methods are likely to have a larger number of outliers, and it may be less trivial to anticipate circumstances under which large deviations occur. In relation to this aspect, we have applied the same generally applicable statistical techniques to further formulate small-data-set models for assessing the accuracy for some properties that are not covered by MG8 nor by MGCDB82. They include the MOR13 model for metal-organic reactions, the SBG5 model for semiconductor band gaps, and MB13 for stress-testing methods with artificial species.

B97-3c: A revised low-cost variant of the B97-D density functional method.

A revised version of the well-established B97-D density functional approximation with general applicability for chemical properties of large systems is proposed. Like B97-D, it is based on Becke's power-series ansatz from 1997 and is explicitly parametrized by including the standard D3 semi-classical dispersion correction. The orbitals are expanded in a modified valence triple-zeta Gaussian basis set, which is available for all elements up to Rn. Remaining basis set errors are mostly absorbed in the modified B97 parametrization, while an established atom-pairwise short-range potential is applied to correct for the systematically too long bonds of main group elements which are typical for most semi-local density functionals. The new composite scheme (termed B97-3c) completes the hierarchy of "low-cost" electronic structure methods, which are all mainly free of basis set superposition error and account for most interactions in a physically sound and asymptotically correct manner. B97-3c yields excellent molecular and condensed phase geometries, similar to most hybrid functionals evaluated in a larger basis set expansion. Results on the comprehensive GMTKN55 energy database demonstrate its good performance for main group thermochemistry, kinetics, and non-covalent interactions, when compared to functionals of the same class. This also transfers to metal-organic reactions, which is a major area of applicability for semi-local functionals. B97-3c can be routinely applied to hundreds of atoms on a single processor and we suggest it as a robust computational tool, in particular, for more strongly correlated systems where our previously published "3c" schemes might be problematic.

Surface functionalization of mesoporous antimony doped tin oxide by metalorganic reaction

Electrically conducting mesoporous antimony doped tin oxide was functionalized by the metalorganic reaction with several Grignard reagents. This fast and efficient grafting approach enables a direct connection of the metal atoms with the organic functionalities avoiding the formation of insulating Si–O linkers, which is of special interest for the interfacial charge transfer processes. Using this approach we introduced vinyl, allyl and phenyl groups into the pores of mesoporous ATO, which was confirmed by IR spectroscopy, TGA and nitrogen sorption measurements. We obtained a high loading of organic groups corresponding to about 50–60% of the monolayer surface coverage. The obtained mesoporous inorganic–organic hybrids can serve as a platform for incorporation of electrochemically active species.

Convenient preparation of (4-iodophenyl)aryliodonium salts

The (4-iodophenyl)aryliodonium salts bis(4-iodophenyl)iodonium, (4-iodophenyl)(4-methoxy-phenyl)iodonium and (4-iodophenyl)(2-thienyl)iodonium, each with three different anions, were prepared using 4-iodo-1-[hydroxy(tosyloxy)iodo]benzene. These are suitable precursor molecules for electrophilic radiofluorination and other 4-iodophenylation reactions, whose products can subsequently serve as reagents for transition metal catalysed cross coupling and other metal organic reactions.

Raman Spectroscopy of the Reaction of Thin Films of Solid-State Benzene with Vapor-Deposited Ag, Mg, and Al

Thin films of solid-state benzene at 30 K were reacted with small quantities of vapor-deposited Ag, Mg, and Al under ultrahigh vacuum, and products were monitored using surface Raman spectroscopy. Although Ag and Mg produce small amounts of metal–benzene adduct products, the resulting Raman spectra are dominated by surface enhancement of the normal benzene modes from metallic nanoparticles suggesting rapid Ag or Mg metallization of the film. In contrast, large quantities of Al adduct products are observed. Vibrational modes of the products in all three systems suggest adducts that are formed through a pathway initiated by an electron transfer reaction. The difference in reactivity between these metals is ascribed to differences in ionization potential of the metal atoms; ionization potential values for Ag and Mg are similar but larger than that for Al. These studies demonstrate the importance of atomic parameters, such as ionization potential, in solid-state metal–organic reaction chemistry.

Off-line LDI-TOF-MS monitoring of simultaneous inorganic and organic reactions on particles levitated in a laboratory environment

Simultaneous inorganic and organic reactions occur on tropospheric particles. The outcomes of these parallel reaction pathways, and particularly the minor reaction products that collectively sum to an appreciable fraction of the particle's mass, are the focus of this work. To characterize condensed phase organic, inorganic, and metal-organic reaction products, we are developing methodology that involves, firstly, the creation of picoliter droplets that carry net charge that are trapped and levitated by an electrodynamic balance in a laboratory environment for the duration of the experiment. Following the rapid evaporation of volatile solvents from the droplets (i.e. seconds), either a residual droplet or a particle remains levitated depending on the atmospheric conditions inside the levitation chamber and the composition of the starting solution from which the initial droplets were created. These droplet residues, whose initial composition is known, are then exposed to gaseous compounds and oxidants that cause transformation of the composition of the levitated droplets/particles by multiphase and heterogeneous reactions that proceed dependent on the species condensing and reacting on the particles. The droplets/particles are then deposited onto a substrate that allows subsequent, and detailed characterization by instrumental methods. In the studies reported here, laser desorption ionization time of flight mass spectrometry was used to characterize reaction products that had formed on the levitated droplets/particles. This apparatus and methodology were used to study the effect of the inorganic reaction of nitric acid vapor with NaCl ( aq ) and NaCl ( s ) on the formation of imines by dehydration reaction between the functional groups of a primary amine and an aldehyde. The product yield of imines was found to be dependent on the sequence of introduction of the gaseous reactants to the levitation chamber.

Enantioselective Synthesis of Tetraponerines by Pd- and Ru-Catalyzed Domino Reactions

An enantioselective synthesis of tetraponerines T4, T6, T7, and T8 in 24−36% overall yield is described. Key steps in this synthesis are a Pd-catalyzed domino allylation and a Ru-catalyzed ring rearrangement. The effect of different substituents on the equilibrium of the metathesis rearrangement has been investigated. To complete the synthesis a sequence of Wacker oxidation and Takai olefination was used. The preparation of four representative tetraponerines differing in stereochemistry, ring size, and side chain employing five metal-organic reactions clearly demonstrates the efficiency of transition metals in organic synthesis.

Syntheses and reactions of metal organics, XX. Syntheses of silane-coupling agents having end-branch fluorocarbon chain and surface modification of glass

Six silane-coupling agents having end-branched fluorocarbon chains: (CF 3) 2CF(CF 2) 4CH 2CH 2Si(CH 3)(OCH 3) 2 ( 1); (CF 3) 2CF(CF 2) 6CH 2CH 2Si(CH 3)(OCH 3) 2 ( 2); (CF 3) 2CF(CF 2) 8CH 2CH 2Si(CH 3)(OCH 3) 2 ( 3); (CF 3) 2CF(CF 2) 4CH 2CH 2Si(OCH 3) 3 ( 4); (CF 3) 2CF(CF 2) 6CH 2CH 2Si(OCH 3) 3 ( 5); (CF 3) 2CF(CF 2) 8CH 2CH 2Si(OCH 3) 2 ( 6); were prepared by the hydrosilylation reaction of dichloro(methyl)silane or trichlorosilane with the corresponding end-branched 1H,1H,2H-polyfluoro-1-alkene ((CF 3) 2CF(CF 2) n CHCH 2, ( n = 4, 6 and 8) in the presence of hydrogen hexachloroplatinate(VI), followed by reaction with sodium methoxide. The application for the surface modification of glass was attempted using these compounds. From measurements of the contact angles θ (°) of water and oleic acid against a modified glass surface, it was found that the silane-coupling agents have high modification ability for surface modification. The oxidation resistance of the modified glass surface was also investigated.

Syntheses and Reactions of Metal Organics. XVII. Synthesis of Silane Coupling Agent Having Fluorocarbon Chain and Surface Modification of Glass Plate

Abstract Four silane coupling agents,1H,1H,2H,2H-polyfluoroalkyl(dimethoxy)(methyl)silanes (1H,1H,2H,2H-henicosafluorododecyl(dimethoxy)(methyl)silane, C10F21C2H4Si(CH3)(OCH3)2, 1H,1H,2H,2H-heptadecafluorodecyl(dimethoxy)(methyl)silane, C8F17C2H4Si(CH3)(OCH3)2, 1H,1H,2H,2H-tridecafluorooctyl(dimethoxy)(methyl)silane, C6F13C2H4Si(CH3)(OCH3)2, and 1H,1H,2H,2H-nonafluorohexyl(dimethoxy)(methyl)silane, C4F9C2H4Si(CH3)(OCH3)2), were prepared by the hydrosilylation of dichloro(methyl)silane with the corresponding 1H,1H,2H-polyfluoro-1-alkene in the presence of hydrogen hexachloroplatinate(IV), followed by the reaction with sodium methoxide. The surface modification of glass plate was attempted using these products. From measurements of the contact angles θ(°) of water and oleic acid against a modified glass plate surface, the coupling agents were found to have high modification ability. The oxidation resistance of the modified glass surface was also investigated.

Syntheses and Reactions of Metal Organics. XVI. Synthesis and Hydrolysis of Dimethoxysilanediyl Bis(polyfluoroalkanoate)

Abstract Four new silicon compounds, dimethoxysilanediyl bis(5H-octafluoropentanoate), (CH3O)2Si[OCO(CF2)4H]2, dimethoxysilanediyl bis(7H-dodecafluoroheptanoate), (CH3O)2Si[OCO(CF2)6H]2, dimethoxysilanediyl bis(9H-hexadecafluorononanoate), (CH3O)2Si[OCO(CF2)8H]2, and dimethoxysilanediyl bis(pentadecafluorooctanoate), (CH3O)2Si[OCO(CF2)6CF3]2, were prepared by the reaction of dichlorodimethoxysilane with sodium salts of fluoro-substituted carboxylic acid. The 1H NMR, 13C NMR, and 19F NMR and IR spectral data of these silicon compounds were obtained. In the course of a study of the stability of the silicon compounds against hydrolysis by using 1H NMR spectral measurements, it was found that the ease of hydrolysis of the SiOCOR and the SiOCH3moieties was exactly same.

Syntheses and Reactions of Metal Organics. XIV. Syntheses of Fluoroalkyl Silicates

Abstract The new compounds, tetrakis(1H, 1H, 3H-perfluoropropyl) silicate, Si(OCH2CF2CF2H)4, tetrakis(1H, 1H, 5H-perfluoropentyl) silicate, Si[OCH2(CF2CF2)2H]4, tetrakis(1H, 1H, 7H-perfluoroheptyl) silicate, Si[OCH2(CF2CF2)3H]4 and tetrakis-(1H, 1H, 9H-perfluorononyl) silicate, Si[OCH2(CF2CF2)4H]4, were prepared by the reaction of silicon tetrachloride with fluoro-substituted alcohols in the presence of ammonia. The 1H, 13C, 19F NMR and IR spectral data of these silicates were obtained.

ChemInform Abstract: Syntheses of Jasmone, Jasmonic Acid, and Some Analogues from Alkyne‐Cobalt Complexes via the Khand Reaction.

AbstractKhand reaction of the alkyne‐hexacarbonyldicobalt complexes (III) ‐ derived from the tosylate (I) by metalorganic reaction ‐ with ethylene (VI) allows the synthesis of the cyclopentenone (VIIa) and jasmone (VIIb).

Syntheses and Reactions of Metal Organics. IX. Reactions of Chloromethoxysilanes with Amides

Abstract The reactions of chloromethoxysilanes, SiCln (OCH3)4-n (n=0, 1, 2, 3, 4), with N,N-dimethylformamide, acetanilide, formamide, acetamide and benzamide have been studied. Chloromethoxysilanes reacted with N,N-dimethylformamide to always give 1 : 2 adducts, but compounds SiCln (OCH3)4-n ·- (n+2) amide have been isolated with other amides. Possible structures for these adducts are discussed on the basis of elemental analyses and IR spectra. The adducts were insoluble in organic solvents.

Syntheses and Reactions of Metal Organics. VIII. The Formation of 2,5-Piperazinediones from Metal Alkoxides and α-Amino Acids

Syntheses and Reactions of Metal Organics. VIII. The Formation of 2,5-Piperazinediones from Metal Alkoxides and α-Amino Acids

Syntheses and Reactions of Metal Organics. X. Preparation of Stannic Chloride Alkoxides

Abstract Reactions involving stannic alkoxide (ethoxide, isopro-poxide and tert.-butoxide) and stannic chloride or acetyl chloride have been studied and compounds of the type SnClx (O[sbnd]R)4-x (x = 1, 2, 3 and R = Et, iPr) were obtained. Where R is tert.-butyl group, corresponding chloro-derivatives could not be obtained, but SnCl(OH) (OtBu)2, SnCl(OtBu)O and Sn2Cl4(OtBu)2O were formed. SnCl(OR)3, SnCl2 (OR)2.CH3COOR and SnCl3 (OR).CH3COOR (R = Et, iPr) were obtained from the reaction of appropriate stannic alkoxide with acetyl chloride. SnCl(OH) (OtBu)2, SnCl(OtBu)O, SnCl2 (OH) (OtBu) and SnCl3(OH).-CH3COOtBu were formed by the reaction of stannic tert.-butoxide with acetyl chloride.

Syntheses and Reactions of Metal Organics. VII. Reactions of n-Butoxytitanium Chlorides with Saturated Cyclic Ethers

Abstract The reactions of n-butoxytitanium chloride, TiCln(OnBu)4−n (n=0,1,2,3,4), with 1,4-dioxane, tetrahydrofuran, and tetrahydropyran have been studied. No adducts have been isolated when n=0,1,but the compounds TiCl2-(OnBu)2·O(CH2CH2)2O, TiCl2(OnBu)2·C4H8O, TiCl2(OnBu)2·C5H10O, TiCl3(OnBu)·O(CH2CH2)2O, TiCl3(OnBu)·2C4H8O, TiCl3(OnBu)·2C5H10O, TiCl4·O(CH2CH2)2O, TiCl4·2C4H8O and TiCl4·2C5H10O have been isolated when n=2,3,4. Possible structures for these adducts were discussed on the basis of elemental analysis, IR spectra, NMR spectra, and molecular weights. The adducts undergo hydrolysis very quickly with moisture.