Low-energy enhancement in the photon strength of 95Mo

A new experimental technique is presented using proton-γ-γ correlations from (94)Mo(d,p)(95)Mo reactions which allows for the model-independent extraction of the photon strength function at various excitation energies using primary γ-ray decay from the quasicontinuum to individual low-lying levels. Detected particle energies provide the entrance excitation energies into the residual nucleus while γ-ray transitions from low-lying levels specify the discrete states being fed. Results strongly support the existence of the previously reported low-energy enhancement in the photon strength function.     

Application of P-stereogenic aminophosphine phosphinite ligands in asymmetric hydroformylation

New chiral aminophosphine phosphinite ligands with a stereogenic center at the aminophosphine phosphorus atom were prepared based on (R,S)-ephedrine as the chiral auxiliary and backbone. Substituents at the chiral aminophosphine as well as at the phosphinite phosphorus atom were varied. These new ligands were applied to the rhodium-catalyzed asymmetric hydroformylation of vinyl arenes. The enantiomeric excess reached up to 77%. 1H and 31P NMR studies of the Rh complexes under syngas pressure reveal that [HRh(CO)2(PP)] complexes with the NP* moiety in an axial position are responsible for enantioselectivity.     

A structural model for a new class of conformationally constrained retinoid: (2Z,4E)-4-[3′,4′-dihydro-1′(2′H)-naphthalene-1′-ylidene]-2-butenoic acid

Racemic (2Z,4E)-4-[3′,4′-dihydro-1′(2′H)-naphthalene-1′-ylidene]-2-butenoic acid (1) is a polyene chain-shortened analog of (9Z)-retinoic acid (3) which uses a tetrahydronaphthyl ring to conformationally constrain the C6-C7 single bond (retinoic acid numbering). The structure of (1) was obtained to determine the effects of the tetrahydronaphthyl ring on the ring to polyene chain conformation as compared to a published crystal structure for (9Z)-retinal (2). The results reveal significant differences between the solid state structures of (1) and (2), particularly for torsion angles about C6, C7 and C8, C9. The title compound crystallizes in the centrosymmetric monoclinic space groupP2₁/n withZ=4. (Cell dimensions:a=10.863(2) Å,b=7.637(2) Å,c=15.781(3) and β=106.11(3)°.) The structure was refined toR=3.88% for those 1132 unique data with |F _o|>6σ(F _o). In the crystal structure, the molecules adopt a hydrogen bonded dimeric structure.     

Synthesis ofcis-[Ru{4,4′-(t-Bu)2bpy}2(PPh3)Cl+][ClO 4 − ] and the crystal structure of its disordered hemiacetonitrile,hemitoluene solvate

The complexcis-[Ru{4,4-(t-Bu)₂bpy}₂(PPh₃)Cl⁺][ClO ₄ ^– ·0.5(toluene)·0.5(MeCN), where 4,4-(t-Bu)₂bpy=4,4-di(t-butyl)-2,2-bipyridyl crystallizes with an ordered racemic mixture of the chiral cations in the centrosymmetric triclinic space group (No. 2). The structure was refined toR=4.42% for those 6426 reflections with 20=5–50^o and |F _o|>6(F). Ruthenium ligand distances are Ru–Cl=2.423(2)Å, Ru–PPh₃=2.346(2)Å and Ru–N=2.056(4)–2.098(4)Å. Both the Ru(II)-containing cation and the perchlorate anion are ordered, but the toluene and acetonitrile exhibit an interesting type of scrambled disorder about the inversion center atx=1,y=1/2,z=0.     

MgSo4—C2H5OH—H2O三元系汽—液—固平衡的研究

H测定过MgSO_4-C_2H_5OH-H_2三元系在25℃、50℃、75℃的液固平衡和部分不饱和溶液汽液平衡的总压和分压。本文补充了30℃、0℃和-5℃时的溶解度数据,得到分层温度和浓度范围,绘出了溶解度图。测定了25℃和30℃饱和溶液的密度,粘度和平衡总压力。根据Jaques“假二元系”理论用Wilson、Uniquac和NRTL活度方程计算了溶