Reaction of a Molybdenum Bis(dinitrogen) Complex with Carbon Dioxide: A Combined Experimental and Computational Investigation.

Refluxing Mo(CO) in the presence of the phosphine-functionalized α-diimine ligand DI allowed for substitution and formation of the dicarbonyl complex, (DI)Mo(CO). Oxidation with I followed by heating resulted in further CO dissociation and isolation of the corresponding diiodide complex, (DI)MoI. Reduction of this complex under a N atmosphere afforded the corresponding bis(dinitrogen) complex, (DI)Mo(N).

Large HO solubility in dense silica and its implications for the interiors of water-rich planets.

Sub-Neptunes are common among the discovered exoplanets. However, lack of knowledge on the state of matter in [Formula: see text]O-rich setting at high pressures and temperatures ([Formula: see text]) places important limitations on our understanding of this planet type. We have conducted experiments for reactions between [Formula: see text] and [Formula: see text]O as archetypal materials for rock and ice, respectively, at high [Formula: see text] We found anomalously expanded volumes of dense silica (up to 4%) recovered from hydrothermal synthesis above ∼24 GPa where the [Formula: see text]-type (Ct) structure appears at lower pressures than in the anhydrous system.

Direct Structural and Chemical Characterization of the Photolytic Intermediates of Methylcobalamin Using Time-Resolved X-ray Absorption Spectroscopy.

Cobalt-carbon bond cleavage is crucial to most natural and synthetic applications of the cobalamin class of compounds, and here we present the first direct electronic and geometric structural characteristics of intermediates formed following photoexcitation of methylcobalamin (MeCbl) using time-resolved X-ray absorption spectroscopy (XAS). We catch transients corresponding to two intermediates, in the hundreds of picoseconds and a few microseconds. Highlights of the picosecond intermediate, which is reduced in comparison to the ground state, are elongation of the upper axial Co-C bond and relaxation of the corrin ring.

Rational design of monocrystalline (InP)(y)Ge(5-2y)/Ge/Si(100) semiconductors: synthesis and optical properties.

In this work, we extend our strategy previously developed to synthesize functional, crystalline Si(5-2y)(AlX)y {X = N,P,As} semiconductors to a new class of Ge-III-V hybrid compounds, leading to the creation of (InP)(y)Ge(5-2y) analogues. The compounds are grown directly on Ge-buffered Si(100) substrates using gas source MBE by tuning the interaction between Ge-based P(GeH3)3 precursors and In atoms to yield nanoscale "In-P-Ge3" building blocks, which then confer their molecular structure and composition to form the target solids via complete elimination of H2. The collateral production of reactive germylene (GeH2), via partial decomposition of P(GeH3)3, is achieved by simple adjustment of the deposition conditions, leading to controlled Ge enrichment of the solid product relative to the stoichiometric InPGe3 composition.

Molecular synthesis of high-performance near-IR photodetectors with independently tunable structural and optical properties based on Si-Ge-Sn.

This Article describes the development of an optimized chemistry-based synthesis method, supported by a purpose-built reactor technology, to produce the next generation of Ge(1-x-y)Si(x)Sn(y) materials on conventional Si(100) and Ge(100) platforms at gas-source molecular epitaxy conditions. Technologically relevant alloy compositions (1-5% Sn, 4-20% Si) are grown at ultralow temperatures (330-290 °C) using highly reactive tetragermane (Ge(4)H(10)), tetrasilane (Si(4)H(10)), and stannane (SnD(4)) hydride precursors, allowing the simultaneous increase of Si and Sn content (at a fixed Si/Sn ratio near 4) for the purpose of tuning the bandgap while maintaining lattice-matching to Ge. First principles thermochemistry studies were used to explain stability and reactivity differences between the Si/Ge hydride sources in terms of a complex interplay among the isomeric species, and provide guidance for optimizing process conditions.

Nanosynthesis routes to new tetrahedral crystalline solids: silicon-like Si3AlP.

We introduce a synthetic strategy to access functional semiconductors with general formula A(3)XY (A = IV, X-Y = III-V) representing a new class within the long-sought family of group IV/III-V hybrid compounds. The method is based on molecular precursors that combine purposely designed polar/nonpolar bonding at the nanoscale, potentially allowing precise engineering of structural and optical properties, including lattice dimensions and band structure. In this Article, we demonstrate the feasibility of the proposed strategy by growing a new monocrystalline AlPSi(3) phase on Si substrates via tailored interactions of P(SiH(3))(3) and Al atoms using gas source (GS) MBE.

Ether-like Si-Ge hydrides for applications in synthesis of nanostructured semiconductors and dielectrics.

Hydrolysis reactions of silyl-germyl triflates are used to produce ether-like Si-Ge hydride compounds including H(3)SiOSiH(3) and the previously unknown O(SiH(2)GeH(3))(2). The structural, energetic and vibrational properties of the latter were investigated by experimental and quantum chemical simulation methods. A combined Raman, infrared and theoretical analysis indicated that the compound consists of an equal mixture of linear and gauche isomers in analogy to the butane-like H(3)GeSiH(2)SiH(2)GeH(3) with an exceedingly small torsional barrier of approximately 0.

Synthesis and fundamental properties of stable Ph(3)SnSiH(3) and Ph(3)SnGeH(3) hydrides: model compounds for the design of Si-Ge-Sn photonic alloys.

The compounds Ph(3)SnSiH(3) and Ph(3)SnGeH(3) (Ph = C(6)H(5)) have been synthesized as colorless solids containing Sn-MH(3) (M = Si, Ge) moieties that are stable in air despite the presence of multiple and highly reactive Si-H and Ge-H bonds. These molecules are of interest since they represent potential model compounds for the design of new classes of IR semiconductors in the Si-Ge-Sn system. Their unexpected stability and high solubility also makes them a safe, convenient, and potentially useful delivery source of -SiH(3) and -GeH(3) ligands in molecular synthesis.

Molecular-based synthetic approach to new group IV materials for high-efficiency, low-cost solar cells and Si-based optoelectronics.

Ge(1-x-y)Si(x)Sn(y) alloys have emerged as a new class of highly versatile IR semiconductors offering the potential for independent variation of band structure and lattice dimension, making them the first practical group IV ternary system fully compatible with Si CMOS processing. In this paper we develop and apply new synthetic protocols based on designer molecular hydrides of Si, Ge, and Sn to demonstrate this concept from a synthesis perspective. Variation of the Si/Sn ratio in the ternary leads to an entirely new family of semiconductors exhibiting tunable direct band gaps (E(o)) ranging from 0.

ClnH6-nSiGe compounds for CMOS compatible semiconductor applications: synthesis and fundamental studies.

We describe the synthesis of a new family of chlorinated Si-Ge hydrides based on the formula ClnH6-nSiGe. Selectively controlled chlorination of H3SiGeH3 is provided by reactions with BCl3 to produce ClH2SiGeH3 (1) and Cl2HSiGeH3 (2). This represents a viable single-step route to the target compounds in commercial yields for semiconductor applications.

Carbon sequestration via aqueous olivine mineral carbonation: role of passivating layer formation.

CO2 sequestration via carbonation of widely available low-cost minerals, such as olivine, can permanently dispose of CO2 in an environmentally benign and a geologically stable form. We report the results of studies of the mechanisms that limit aqueous olivine carbonation reactivity under the optimum sequestration reaction conditions observed to date: 1 M NaCl + 0.64 M NaHCO3 at Te 185 degrees C and P(CO2) approximately equal to 135 bar.

Synthesis of butane-like SiGe hydrides: enabling precursors for CVD of Ge-rich semiconductors.

The synthesis of butane-like (GeH(3))(2)(SiH(2))(2) (1), (GeH(3))(2)SiH(SiH(3)) (2), and (GeH(3))(2)(SiH(2)GeH(2)) (3) Si-Ge hydrides with applications in low-temperature synthesis of Ge-rich Si(1-x)Ge(x) optoelectronic alloys has been demonstrated. The compositional, vibrational, structural, and thermochemical properties of these compounds were studied by FTIR, multinuclear NMR, mass spectrometry, Rutherford backscattering, and density functional theory (DFT) simulations. The analyses indicate that the linear (GeH(3))(2)(SiH(2))(2) (1) and (GeH(3))(2)(SiH(2)GeH(2)) (3) compounds exist as a mixture of the classic normal (n) and gauche (g) conformational isomers which do not seem to interconvert at 22 degrees C.

Synthesis and fundamental studies of (H3Ge)xSiH4-x molecules: precursors to semiconductor hetero- and nanostructures on Si.

The synthesis of the entire silyl-germyl sequence of molecules (H(3)Ge)(x)SiH(4)(-)(x) (x = 1-4) has been demonstrated. These include the previously unknown (H(3)Ge)(2)SiH(2), (H(3)Ge)(3)SiH, and (H(3)Ge)(4)Si species as well as the H(3)GeSiH(3) analogue which is obtained in practical high-purity yields as a viable alternative to disilane and digermane for semiconductor applications. The molecules are characterized by FTIR, multinuclear NMR, mass spectrometry, and Rutherford backscattering.

Exploration of the role of heat activation in enhancing serpentine carbon sequestration reactions.

As compared with other candidate carbon sequestration technologies, mineral carbonation offers the unique advantage of permanent disposal via geologically stable and environmentally benign carbonates. The primary challenge is the development of an economically viable process. Enhancing feedstock carbonation reactivity is key.

In situ observation of CO2 sequestration reactions using a novel microreaction system.

A novel, externally controlled microreaction system has been developed to provide the first in situ observations of the reaction processes that control CO2 sequestration via mineral carbonation. The system offers pressure (to 20 MPa), temperature (to 250 degrees C), and activity control suitable for investigating a variety of fluid-fluid and fluid-solid interactions of environmental interest. Mineral sequestration efforts to date have effectively accelerated carbonation, a natural mineral weathering process, to an industrial timescale.