STRUCTURAL RULES OF TRANSITIONMETAL CARBONYL COMPOUNDS

In this article we have proposed two topological rules to account for the electronic structures of transition-metal carbonyl compounds. The second rule is applied to those which have polyhedral metalhc skeletons with triangular faces and their derivates, while the first rule is applied to all the others We have used these two rules to analyze 261 structure-known compounds with the number of metal atoms from 2 to 12, and the results show that the two rules are in good agreement with the experimental facts. Furthermore, we have also derived from the second rule a formula which can be used to account for the electronic structures of closedpacking carbonyl compounds and which is the same as that given by Ciani and his coworkers.     

CONFORMATIONAL AND ELECTRONIC INTERACTION STUDIES OF α-SUBSTITUTED CARBONYL COMPOUNDS. XV. α-(ARYLSULFINYL)-p-SUBSTITUTED ACETOPHENONES

Abstract

The v_CO IR analysis of α-(p-phenylsulfinyl)-p-substituted acetophenones X-φC(O)CH₂S(O)φ-Y 1–8, being X and Y = NO₂, H and OMe substituents, supported by ab initio calculations of the α-methylsulfinyl/acetophenone (model compound) along with the X-ray geometrical data for 1,7 and 8, indicates the existence of the cis ₂ and gauche rotamers for compounds 1-4 and 6. Compounds 5,7 and 8 present another less stable and more polar cis ₁ rotamer. The cis ₂ rotamer concentration for 4 (ca. 97% in CCl₄) is reduced to ca. 50% for 2,3,5-7 and to ca. 20% for 1 and 8. This behavior is discussed in terms of O^δ- _(CO—S^δ+ _(SO) charge transfer and Coulombic interactions, which stabilize the cis ₁ rotamer, and the π*_CO/δ_C-S, π_CO/n_s and π*_CO/δ_C-S orbital interactions, which stabilize the gauche rotamers. The progressive more negative carbonyl cis ₂ shifts (Δv_c), when X varies from NO₂ to H and to OMe for the same Y, along with the unexpected NAE values of the α-methylene carbon chemical shifts for compounds 1–8 give further support for the existence of a strong intramolecular complex betwen C=O and S=O dipoles which stabilizes the cis ₂ rotamer. The progressive more negative carbonyl gauche shifts (Δv_g), when X varies from NO₂ to H and to OMe for the same Y, is in line with the higher contibution of the interaction π_CO/δ*_C-S, which stabilizes the gauche rotamer of the title compounds.     

HYDROFORMYLATION CATALYSIS USING POLYMER-SUPPORTED MULTINUCLEAR RHODIUM CARBONYL CLUSTER CATALYSTS

A series of polymer-supported tetranuclear rhodium carbonyl cluster catalysts were prepared b the reaction of Rh_4(CO)_(12) with several kinds of polymer supports such as crosslinked poly (N-vinylpyrrolidone) (PNVP) and crosslinked poly ( styrene-co-maleic anhydride) (PMAn), and subsequently were used to catalyze the hydroformylation of olefins. The catalysts were characterized by IR, SEM and XPS. The influence of the supports structure and crosslinking, metal's content and particle size of the supports on the catalysts hydroformylation properties was studied. The factors which affect the catalytic conversion were also examined. The experimental results show that the polymer-supported Rh cluster catalysts possess very high catalytic activity and aldehyde selectivity as well as good reproducibility.     

CARBON MONOXIDE HYDROGENATION OVER SILICA-SUPPORTED RHODIUM CARBONYL CLUSTER CATALYSTS

The CO hydrogenation over Rh_4(CO)_(12)SiO_2 catalyst promoted with man-ganese and lithium was reported.As compared with conventional RhCI_3/SiO_2 catalyst,silica-supported rhodium carbonyl cluster catalysts have higher reactive activities.Manganese increases CO conversion by more than one order of magnitude and lithiumlowers CO hydrogenation activity,whereas Rh_4(CO)_(12)-MnCl_2-LiCI/SiO_2 catalyst giveshigher CO conversion and selectivity to C_2-oxygenate.XPS and IR spectra show thatmanganese stabilizes Rh(Ⅰ)ions and facilitated CO molecule activation via its syner-gism with rhodium enhancing CO conversion obviously.ESR results preliminarily revealthe interaction of rhodium with manganese.The mechanism of CO hydrogenation is dis-cussed primarily.     

BASE STRENGTH DISTRIBUTION OF ALKALIZED ALUMINA FOR CARBONYL SULFIDE HYDROLYSIS REACTION

IntroductionForx`ell-knot`nreasons.thcremovalofcarbon}.lsulfide(C0S)froms}nthcsisgashasattractedmuchattentioninrecent},ears.0neoftheavailableindUstrialprocessest`rhichareconsideredtobethemostpromisingisthecatal}tichydrolysisofcarbonylsulfideaccordingtothefollot`ingreactiontC0S H2O=H2S CO2Atpresent,hot`ever,inthcpublishedpapersll-lthemechanismandkinCicsabotthisreactioncannotcompletelymectthcpracticalrequirementofindustry.Inourprevious.DrkI5'6lthckineticsofcarbon}lsulfidchydrolysis,thcchar…     

CATALYTIC PERFORMANCE OF MIXED-BIMETALLIC RUTHENIUM CARBONYL CLUSTERDERIVED CATALYSTS IN CO HYDROGENATION

The bimetallic catalysts prepared from SiO_2-supported Ru-Co,Ru-Fe and Ru-Mo carbonyl clusters exhibited high yields and selectivitiestowards oxygenates such as C_1-C_5 from CO+H_2,in contrast to the catalystsprepared from homometallic and bimetallic Ru,Ru-Ni,Ru-Rh,Ru-Mn,and Ru-Cr carbonyl clusters.The FTIR investigation revealed that the 1584 cm~(-1)species plays an important role in the formation of oxygenates in COhydrogenation,which is possibly assigned to surface formyl species.     

CONVERSION OF ACETALS AND KETALS TO CARBONYL COMPOUNDS PROMOTED BY ZrCl_4-NaBH_4

In our study on the chemistry of ZrCl_4-NaBH_4,we have found that aldehydes and ketonescan be regenerated from acetals and ketals at 30℃ in Et_2O in high yield The reaction mechanismwas discussed.     

OXIDATION OF α-METHYL OR α-METHYLENE GROUPS IN CARBONYL COMPOUNDS WITH AMMONIUM CHLOROCHROMATE

This paper reports a new method for oxidizing the α-methyl orα-methylene groups in carbonyl compounds into 1,2-dicarbonyl compoundsby ammonium chlorochromate(ACC).     

ACTIVITY AND SELECTIVITY OF RUTHENIUM CARBONYL,KETENYLIDENE AND CARBIDE CLUSTER-DERIVED CATALYSTS FOR ETHYLENE HYDROFORMYLATION AND CO HYDROGENATION

The ruthenium catalyst prepared from triruthenium ketenylidenecluster exhibited high catalytic activity in hydroformylation of ethylene and COhydrogenation,compared with the catalyst from[HRu_3(CO)_(11)]~-.The highactivity possibly resulted from the ketenyl group(CCO)that could be partlyconverted to carbide species.     

STERIC CONTROL OF THE P-CHIRAL GROUP IN GRIGNARD ADDITION TO THE CARBONYL GROUP OF α - KETOPHOSPHINE OXIDE

Abstract

1,2-Asymmetric inductions in Grignard addition to the carbonyl group of α-keto P-chiral phosphine oxides have been investigated. The favoured reaction product erythro-, 6, is thermodynamically less stable than the threo isomer. This seems to be the first stereochemical evidence of the reversible character of reaction addition of sec-phosphine oxides to the carbonyl group.     

MIXED-BIMETAL RUTHENIUM CARBONYL CLUSTERS SUPPORTED ON SILICA:ACTIVITY AND SELECTIVITY IN CO+H_2 CONVERSION

The catalytic performance of bimetallic Ru-M(M=Co,Fe,Ni,Mo,Rh,Cr,Mn)catalystS prepared from a series of Ru-M carbonyl clustersin CO hydrogenation has been investigated.The catalysts derived from Ru-Co,Ru-M and Ru-Mo bimetallic carbonyl clusters showed high activity and selec-tivity for higher oxygenates,compared with the Ru_6/SiO_2,catalyst Preparedfrom impregnation of monometallic cluster Ru_6C(CO)_(17).For Ru-Ni and Ru-Rh catalysts,they did not show high promotion for the formation of oxygenatesalthough the selectivity was over 10% at 519K.The promoters such as Mnand Cr in Ru-Mn and Ru-Cr catalysts intensively led to a decrease of oxygenateamount,in comparison with to Ru_6/SiO_2 catalyst.In silu FT-IR studies re-vealed that the intensity of band at 1584 cm~(-1) for Ru-M(M=Co,Fe and Mo)bimetallic cluster-derived catalysts at 453 K under syngas(CO/H_2=0.5) has agood linear relationship to rates of oxygenate formation,whereas the band at1584 cm~(-1)was not observed for Ru-Mu,Ru-Cr,Ru-Rh and Ru-Ni bimetall     

Condensed aromatics—XXIV. Cyclo[d.e.d.e.e.d.e.d.e.e]decakisbenzene

The macrocyclic condensed aromatic hydrocarbon C₄₀H₂₀ cyclo[d.e.d.e.e.d.e.d.e.e] decakisbenzene is treated. It belongs to the class of cycloarenes. The simple Hückel molecular orbital analysis has been performed and employed in the construction of a harmonic force field. The set of calculated vibrational frequencies is reported.     

Condensed aromatics—XXIII. Cyclo[d.e.d.e.d.e.d.e.d.e.d.e]dodecakisbenzene (kekulene)

Some topological properties of coronoids are given. These systems have chemical counterparts in cycloarenes. For one of these molecules, viz. C₄₈H₂₄ kekulene, the simple Hückel molecular orbital analysis has been performed and employed in the construction of a harmonic force field. Finally the set of calculated vibrational frequencies is reported.     

THE STUDY OF POISONING EFFECT OF SULPHUR COMPOUNDS ON ACTIVITY OF IRON CARBONYL CLUSTERS FOR WATER GAS SHIET REACTION

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MICHAEL ADDITION OF NITROALKANE TO α,β-UNSATURATED CARBONYL COMPOUNDS ON KF / Al_2O_3/ PEG4000

Michael addition of nitroalkanes to α,β-unsaturated carbonyl compounds occurs in the presence of KF/AI_2O_3/PEG4000 without solvent.Yields are fair to good and work-ups are easy.