Two coordination polymers, [Ag 2 (pydca)(bbbi) 2 ] n (1) and [Co 2 (pydca) 2 (bbbi) 3 ] n ·nH 2 O (2) [pydca = pyridine-2,6-dicarboxylate, bbbi = 1,1Ј-(1,4-butylene)bis-1H-benzimidazole)] were hydrothermally synthesized and characterized by elemental analysis, IR spectroscopy, TG, PXRD, and single-crystal X-ray diffraction. Compound 1 features a one-dimensional helical chain structure bridged by bbbi

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Vapor-liquid equilibrium (VLE) data have been measured with a statictype VLE apparatus for the dimethyl ether (DME)-diisopropyl ether (DIPE) binary system at five temperatures within the range from 293.04 K to 352.70 K. An isothermal correlation for the experimental data has been carried out based on the Peng-Robinson equation of state. The regressed binary interaction parameters were used to estimate VLE for the DME-CO 2 -DIPE ternary system at 298.15 K. From the study, it is demonstrated that DIPE is an excellent absorbent for separation in the DME synthesis process from syngas.

Asymmetric hydroformylation (AHF) catalyzed by transition metal (TM) complexes bearing chiral phosphorus ligands is one of the most powerful synthetic ways that could provide chiral aldehydes directly from alkenes and syngas in one step. Experiments have proved the efficiency of Rh catalyst with hybrid phosphorus ligands owning two different phosphorus moieties in AHF. Herein the origin of enantioselectivity of AHF catalyzed by RhH(CO)2[(R,S)-Yanphos] was studied at M06/BSI level using the density functional theory (DFT) method to unveil a fundamental understanding on factors contributing to the efficiency in AHF. The alkene insertion step is supposed to be the chirality-determining step in the whole catalytic cycle of the Rh-Yanphos system. Four possible pathways of styrene (Sub1) insertion step (pathways R1, S1, R2, and S2) were discussed; the calculated results indicate that pathways R1 and S2 are proposed to be two dominant alkene insertion pathways and that styrene tends to adopt apical coordination mode (A mode) to Rh center in pathways R1 and S2 compared to equatorial coordination mode (E mode) in pathways R2 and S1. The enantioselectivity of AHFs of ten alkene substrates (CH2═CH-R, R═Ph, C(═O)OCH3, Ph-(p)-Me, Ph-(p)-OMe, Ph-(p)-(i)Bu, Ph-(p)-F, Ph-(p)-Cl, Ph-(o)-F, OC(═O)-Ph and O-Ph, corresponding alkenes are abbreviated as Sub1 to Sub10, respectively) were also investigated. The predicted chiralities agree well with experimental results. The present work suggests that the relative stabilities of coordination modes (A/E mode) of alkene to 2 (RhH(CO)[(R,S)-Yanphos]) might be of importance in the enantioselectivity of AHF catalyzed by Rh-Yanphos.