Won K. Seok

Hydroformylation of olefins with formaldehyde in the presence of RhHCO(PPh3)3

Abstract Olefins, such as allyl alcohol, propylene, 1-hexene, styrene, methyl acrylate and acrolein, were hydroformylated with formaldehyde to form corresponding aldehydes. Allyl alcohol and methyl acrylate which have oxygen at β position to double bond showed higher reactivities and selectivities to n -products than those of olefins without oxygen such as propylene, 1-hexene and styrene. 4-Hydroxybutanal was formed as a major product from the reaction of allyl alcohol with formaldehyde under nitrogen atmosphere at 100°C and 5 h (yield: 26%, n -/ iso -=21). The addition of syn-gas or excess phosphine to the reaction mixture inhibited hydroformylation with decreasing n -/ iso -ratio. The hydroformylation of olefins without oxygen gave better yield to aldehydes under syn-gas condition. From in situ IR experiments, the formation of formyl ligand coordinated to metal center was observed. Variable temperature NMR experiment was also performed to verify the mechanism. Based on those observations, a plausible reaction mechanism was proposed.

Indolocarbazole based small molecules: an efficient hole transporting material for perovskite solar cells

To date, Spiro-OMeTAD, which is an expensive organic compound, has been used as the benchmark hole transporting material (HTM) in perovskite based solid state solar cells. Development of an inexpensive HTM with competitive performance to Spiro-OMeTAD is therefore significantly important for the commercialization of perovskite cells. Herein, an indolocarbazole based small molecule derivative (C12-carbazole) has been introduced as an environmentally stable, cost effective and highly efficient HTM. In contrast to the power conversion efficiency of 9.62% exhibited by the Spiro-OMeTAD based solid state solar cell, the C12-carbazole based device under the same experimental conditions has demonstrated an enhanced power conversion efficiency of 11.26%. The improved photovoltaic performance of the C12-carbazole based device is attributed to reduced carrier recombination by a better hole extraction ability of the C12-carbazole, which has demonstrated remarkably higher hole mobility compared to Spiro-OMeTAD.

SYNTHESIS, STRUCTURAL CHARACTERIZATION AND SEMIEMPIRICAL CALCULATIONS OF THE RUTHENIUM AZIDE COMPLEX RU(TPY)(PPH3)2(N3)CLO4

Abstract The reaction of [Ru(tpy)(PPh3)2Cl][PF6] (tpy, 2,2′:6′,2′′-terpyridine) with NaN3/NaClO4 in acetone/water produced the ruthenium(II) complex [Ru(tpy)(PPh3)2(N3)][ClO4] (1), which contains a coordinated azide unit with Ru–N=2.132(5) A. The new Ru azide complex 1 was identified and characterized by elemental analysis, IR, Raman and multinuclear NMR (1H, 14N, 31P) data. Crystals were grown from an acetonitrile/diethyl ether solution and the crystal structure was determined by a low-temperature single crystal X-ray diffraction study. Crystallographic data for 1: triclinic, P 1 , a=10.9905(5), b=13.4741(6), c=17.8532(9) A, α=90.6760(10), β=96.4000(10), γ=105.5270(10)°, V=2529.07(21) A3, ρ=1.422 g cm−3, Z=2. The experimentally obtained structural parameters for compound 1 compare reasonably well with those calculated at the semi-empirical ZINDO/1 level of theory.

A comparative study on structures and theoretical models of Rh azido complexes

The syntheses of PF 6 − salt of six-coordinate Rh(III) azido complexes containing polypyridyl ligands have been accomplished by treatment of the corresponding Rh(III) chloride with NaN 3 in EtOH–H 2 O followed by the addition of NH 4 PF 6 . The complexes have been characterized by UV–vis, FTIR, 1 H and 14 N-NMR spectroscopy along with elemental analysis. The X-ray crystal structures of compounds [Rh(tpy)(phen)(N 3 )](PF 6 ) 2 ( 1 ·(PF 6 ) 2 , tpy: 2,2′:6′,2″-terpyridine, phen: 1,10-phenanthroline) and [Rh(tpy)(bpy)(N 3 )](PF 6 ) 2 ( 2 ·(PF 6 ) 2 , bpy: 2,2′-bipyridine) confirm that a rhodium atom is six-coordinate and the tpy and bpy or phen ligands are orthogonal and the RhN 3 distances are 2.038(7) and 2.048(6) A, respectively. The two NN distances for the coordinated azide in complex 1 ·(PF 6 ) 2 are identical with distances of 1.17 (1) and 1.17 (1) A. However, the two NN distances for the azido group in the complex 2 may or may not be inequivalent with 1.170(8) and 1.15(1) A. The bond angles formed by the azide group, Rh, and the axially-positioned nitrogen atom are 172.1(3) and 173.5(8)°. In order to answer the question as to whether the two NN distances in 2 would be expected to be different, calculations were carried out at HF/LANL2DZ and HF/SDD levels of theory. The results indeed predict the NN distances in 2 to be different.

Theoretical Study on H3N3O3 for Solid Rocket Propellant

It is worthy to point out that decom-position of those compounds affords large volumes of en-vironmentally friendly and green dinitrogen molecule. Priorto undertaking a possibly costly and time-consuming syn-thesis, a theoretical approach can be taken to evaluate pro-posed compounds. The development of accurate models andsimulations of high-energetic, dense materials has beencontinuously pursued with the advent of computationalcapabilities.

Structural Characterization Of Rh(Iii) Complexes Containing The Polypyridyl Ligands And Some Properties Of Their Derivatives

The structures of the compounds [Rh(bpy)2(py)(Cl)](ClO4 )2 (2 (ClO4 )2) and [Rh(phen)2(py)- (Cl)](ClO4 )2 (7 -(ClO4 )2) were determined by single-crystal X-ray diffraction. Both complexes show a six-coordinate rhodium atom with two bpy or phen ligands in the cis configuration. The Rh-Cl distances are 2.334(3) and 2.323(2) Å, respectively. The bond angles N-Rh-Cl formed with the axially-positioned nitrogen atom are 174.4(2) and 173.8(2)°. The oxidation of aquo complexes, prepared from the corresponding rhodium chloride complexes, by two equivalents of Ce(IV) in 60% HCIO4 solution yields the corresponding mono-oxo products. All complexes have been identified and characterized by elemental analyses, IR, and 1H NMR data

Synthesis, Spectroscopic Investigation, and Theoretical Study of the Ruthenium Diazide Complex [Ru(tpy)(PPh3)(N3)2]

The reaction of [Ru(tpy)(PPh3)(Cl)2] (tpy = 2,2′:6′,2″-terpyridine) with sodium azide in acetone/water afforded [Ru(tpy)(PPh3)(N3)2]. The new Ru-diazide complex was fully characterized by elemental analysis, IR, Raman, and multinuclear NMR spectroscopy. The structures, energies and vibrational frequencies of the ruthenium diazide isomers, cis- and trans- [Ru(tpy)(PMe3)(N3)2] (Me=CH3), were calculated at the semi-empirical ZINDO/1 level of theory.

Theoretical Study on H 3 N 3 O 3 for Solid Rocket Propellant

It is worthy to point out that decom-position of those compounds affords large volumes of en-vironmentally friendly and green dinitrogen molecule. Priorto undertaking a possibly costly and time-consuming syn-thesis, a theoretical approach can be taken to evaluate pro-posed compounds. The development of accurate models andsimulations of high-energetic, dense materials has beencontinuously pursued with the advent of computationalcapabilities.

Theoretical Study on H3N3O3for Solid Rocket Propellant

It is worthy to point out that decom-position of those compounds affords large volumes of en-vironmentally friendly and green dinitrogen molecule. Priorto undertaking a possibly costly and time-consuming syn-thesis, a theoretical approach can be taken to evaluate pro-posed compounds. The development of accurate models andsimulations of high-energetic, dense materials has beencontinuously pursued with the advent of computationalcapabilities.