The N-substituents on the backbone of Ph 2 PN(R)Si(CH 3 ) 2 CH 2 PPh 2 -and [Ph 2 PCH 2 Si(CH 3 ) 2 ] 2 N-(R)-type silylated-diphosphinoamine (Si-PNP) systems have been observed to have a significant impact on their catalytic performance in ethylene oligomerization reactions. Cr precatalyst 3, bearing an isopropyl ( i Pr) substituent, affords the most efficient catalytic system and exhibited the highest selectivity (83%) toward 1-octene (1-C 8 ) and showed a catalytic activity of more than 76,700 g(product)•g(Cr) −1 •h −1 under experimental conditions. Single-crystal analysis results revealed the influence of steric constraints around the catalytically active center and established a relationship between the product selectivity and the P−Cr−P bite angle. Furthermore, DFT calculations indicate that the catalytic system based on precatalyst 3 faces a low energy barrier in the formation of 1-C 8 and therefore shows high selectivity toward the 1-C 8 fraction. Modification in the backbone length may alter the binding mode of the ligands from mononuclear-bidentate (k 2 -P, P) to mononuclear-tridentate (k 3 -P, N, P), which consequently switches the ethylene tetramerization systems to ethylene trimerization systems.

The supramolecular self-assembly of para-substituted tetraphenylporphyrin complexes of zinc(II), Zn(p-X)TPP, with imidazolyl-linked porphyrinatomanganese(III), Mn(p-lmBPTPP)Cl, driven by coordinative bonding has been investigated by fluorescence spectra, electrospray mass spectrometry, 1 H-n.m.r. and u.v.-vis. spectra. The association constants of the supramolecular complexes, K c , were calculated using fluorescence spectroscopic titration data at suitable dilute concentration ranges in which the fluorescent quenching of Zn(p-X)TPP by Mn(p-ImBPTPP)Cl is a static process. The electronic effect in the supramolecular self-assembly of para-substituted . porphyrinatozinc(II) with imidazolyl-linked porphyrinatomanganese(III) is discussed. The non-linear dependence of log K c on the Hammett constants was found, which suggested that the electronic effect in para-substituents of tetraphenylporphyrin complexes of zinc(II) is an important, but not a sole factor effecting the association constants of the Zn(p-X)TPP-Mn(p-ImBPTPP)Cl supramolecular complexes. The results indicate that the closed conformation of the Zn(p-X)TPP-Mn(p-ImBPTPP)Cl supramolecular complex is another important factor effecting the association constants of the Zn(p-X)TPP-Mn(p-ImBPTPP)Cl supramolecular complexes.

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A novel coupled reaction–extraction–alcohol precipitation process was proposed to mineralize CO2 as MgCO3·3H2O directly by abandoned MgCl2. Rod-like crystal MgCO3·3H2O was obtained, and the conversion rate of MgCl2 increased sharply by using this novel coupled reaction–extraction–alcohol precipitation process. The effect of an added C1–C3 alcohol precipitation agent on the conversion rate of MgCl2 was in the following order: ethanol > isopropanol > n-propanol > methanol. Moreover, the optimal conditions for the highest conversion rate of MgCl2 by single-factor experiments were obtained as follows: initial concentration of MgCl2 solution is 2 mol·L–1, volume ratio of ethanol and aqueous phase is 2, mole ratio of N235 and aqueous phase is 2, volume ratio of diluent and N235 is 0.5, with a stirring rate of 300 r·min–1 at 298.15 K and at atmospheric pressure.

The thermal dissociation of tri-n-octylamine hydrochloride (TOAHCl) was investigated using both the quantum chemical simulation and experimental methods. The pathway through which a mixture of trin-octylamine (TOA) and hydrogen chloride (HCl), rather than din -octylamine (DOA) and 1-chlorooctane, are produced has been determined through transition state (TS) search with Intrinsic Reaction Coordinate (IRC) calculations. Particularly, strong agreement between the experimental FTIR spectra and that of TOA demonstrates the same result for the first time. Moreover, the thermal dissociation of TOAHCl proceeds in two continuous steps, which is different from the low molecular mass amine hydrochlorides. The experimental enthalpy of the dissociation was 70.793 kJ mol −1 with DSC measurement which is very close to the density functional theory (DFT) calculation result 69.395 kJ mol −1. Furthermore, with the aid of DFT calculations, some other important thermochemical characteristics such as crystal lattice energy with the value of 510.597 kJ mol −1 were evaluated by means of Born-Fajans-Haber cycle.

(1 Os ), were studied computationally by using the density functional theory (DFT). 1 Ru is a recently reported highly efficient catalyst for this reaction. 1 Fe and 1 Os are two analogues of 1 Ru with the Ru atom replaced by Fe and Os, respectively. The total free energy barriers of the reactions catalyzed by 1 Ru , 1 Fe and 1 Os are 24.2, 24.0 and 29.0 kcal/mol, respectively. With a barrier close to the experimentally observed Ru complex, the newly proposed iron complex is a potential low-cost catalyst for the reduction of carbon dioxide to formaldehyde under mild conditions. The electronic structures of intermediates and transition states in these reactions were analyzed by using the natural bond orbital theory.

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