Search

Experimentally, gas-phase reactions between diborane (B2H6) and carbon monoxide (CO) produce borane carbonyl (BH3CO) and a less volatile material. To elucidate the unknown part of the products, we ...

Gas-phase reactions between silane (SiH4) and ammonia (NH3) were investigated using ab initio calculations at the CCSD(T)/6-311++g**//MP2/6-31+G* level. Within the energy range of 180 kcal/mol, we located 34 equilibrium and 23 transition states on the potential energy surfaces of the Si−N−H systems. The initially weakly bonded molecular complex H3N−SiH4 eliminates the first hydrogen molecule (H2) to form the Si−N bond three ways. The first route is through a dihydrogen-bonded transition state, over a barrier of 49.31 kcal/mol, leading directly to the most stable product silylamine (H2N−SiH3). The second route is through SiH4 dissociating into SiH2 and H2, over a barrier of 57.47 kcal/mol, leading to the dative-bonded silylammonia complex H3N−SiH2. The third route is through a stepwise atomic dissociation and radical formation process, over a barrier of 131.21 kcal/mol, also leading to H3N−SiH2. With more energy, both H2N−SiH3 and H3N−SiH2 are liable to further H2 or H elimination, leading to smaller speci...

Initial gas-phase reactions for a system containing silane (SiH4) and hydrogen (H2) were investigated using ab initio calculations at the MP2/6-311++g** level. Twenty-four minimum and 19 transition states were located on the potential energy surface of the neutral species containing one or two silicon atoms. The bonding nature of each species was elucidated by topological analyses of electron density using Bader's AIM theory. The reaction pathways were classified into three parts: Part (I) shows elimination of the first H2 and formation of disilane (Si2H6). Part (II) shows elimination of the second H2 and formation of five disilene (Si2H4) isomers. Part (III) shows elimination of the third H2 and formation of four disilyne (Si2H2) isomers. More energy is required to obtain species with less hydrogen content, and such species are more likely to be stabilized by a hydrogen bridged bond (Si−H−Si). Calculated IR spectra, dipole moments, and rotational constants were provided for comparison with the experiments.

Initial gas-phase reactions for a system containing silane (SiH4) and hydrogen (H2) were investigated using ab initio calculations at the MP2/6-311++g** level. Twenty-four minimum and 19 transition states were located on the potential energy surface of the neutral species containing one or two silicon atoms. The bonding nature of each species was elucidated by topological analyses of electron density using Bader's AIM theory. The reaction pathways were classified into three parts: Part (I) shows elimination of the first H2 and formation of disilane (Si2H6). Part (II) shows elimination of the second H2 and formation of five disilene (Si2H4) isomers. Part (III) shows elimination of the third H2 and formation of four disilyne (Si2H2) isomers. More energy is required to obtain species with less hydrogen content, and such species are more likely to be stabilized by a hydrogen bridged bond (Si−H−Si). Calculated IR spectra, dipole moments, and rotational constants were provided for comparison with the experiments.