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A simplified kinetic model was developed for the rhodium-catalyzed low-pressure hydroformylation using chelating phosphite ligands. This allowed the determination of the relative rate constants for linear and branched aldehyde formation starting with terminal olefins using data from complex product mixtures. Structural data were obtained using X-ray crystallography and served as the basis for molecular modeling of rhodium complexes with such chelating ligands. The interaction of linear and branched alkyl groups with the ligand environment in such complexes was quantified using molecular modeling. The energy differences obtained with molecular modeling were plotted against the energy differences obtained from kinetic experiments and a linear correlation was found. This type of approach, i.e., development of a structure–activity relationship, can be used to quickly and efficiently investigate such catalytic systems.

The sections in this article are Introduction History Thermochemistry Reaction Mechanism Mass Transfer and Kinetics Catalysts Nature and Performance of the Pt–Rh catalyst Form and Arrangement Operating Life Ignition and Activation Catalyst Poisons and Platinum Damage Catalyst Composition Effect of Rhodium in the Pt–Rh Catalyst Behavior of Other Metals Oxide Catalysts Processes Occurring at the Catalyst Surface Recent Developments Catalyst Research Knitted Gauzes Reaction Engineering Gas Composition Reaction Temperature Reaction Pressure Catalyst Loading Noble Metal Losses Recovery of Noble Metals Gauzes of PdAu Alloys Recent Investigations Process Engineering Equipment Filter and Mixer Burner and Waste Heat Boiler Processes DeNOx and DeN2O [38] Introduction DeNOx DeN2O Keywords: ammonia oxidation; reaction mechanism; platinum; rhodium; palladium; gauzes; reaction engineering

Durch Umsetzung von Germanium(II)-chlorid (als 1,4-Dioxan-Komplex) mit dem substitutionslabilen Organomangan-Komplex (η5-C5H5)Mn(CO)2(THF) (1) im Molverhaltnis 1:2 erhalt man den neuen μ-Dichlorogermylen-Komplex μ-GeCl2)[(η5-C5H5) -Mn(CO)2]2 (3), dessen Molekulstruktur durch Einkristall-Rontgenstrukturanalyse bestimmt wurde. Durch reduktive Enthalogenierung von 3 mittels Zink-Staub in Gegenwart von weiterem 1 gelingt eine schrittweise Synthese der bekannten Verbindung μ3-Ge)[(η5-C5H5) Mn(CO)2]3 (4), die aus 1 auch nach einem Eintopfverfahren zuganglich ist. Multiple Bonds Between Main-Group Elements and Transition Metals, LVIII. – Germylene and Germanium Complexes of Manganese The novel μ-dichlorogermylene complex 3 (μ-GeCl2)[(η5-C5H5) -Mn(CO)2]2 is formed upon treatment of the substitutionally labile organomanganese complex (μ5-C5H5)Mn(CO)2(THF) (1) with germanium(II) chloride (as 1,4-dioxane adduct) in a molar ratio of 2:1. The structure of 3 was established by a single-crystal X-ray diffraction study. Reductive dehalogenation of 3 by zinc dust in the presence of further 1 represents a stepwise synthesis of the known germanium complex (μ3-Ge)[(η5-C5H5) Mn(CO)2]3 (4), which is also accessible starting from 1 in a one-pot synthesis.

The compound (μ-H) 2 Os 3 (CO) 9 (μ 3 -Te) has been prepared from Os 3 (CO) 10 -(NCCH 3 ) 2 and H 2 Te, and its structure has been determined by X-ray crystallography.

125 Te and 77 Se NMR spectroscopy of transition metal complexes containing “naked” tellurium or selenium as a bridging ligand allow the nature of differently bound tellurium or selenium ligands to be determined, as well as the detection of neighbouring hydrido ligands by analyzing the 1 H- 125 Te( 77 Se) couplings. A correla-tion of structural features with chemical shifts of these heteronuclei is not possible owing to the dominant paramagnetic term of the chemical shift.

Die metallorganischen Sulfide (η5-C5R5)W(CO)3 –CH2–S–C6H5 (R = H: 1a; R = Me: 1b reagieren mit meta-Chlorperbenzoesaure (MCPBA) zu den Sulfoxiden (η5-C5R5)W(CO)3 CH2S(O)C6H5 (2a, b). Eine Rontgenstrukturanalyse von 2a zeigt eine Struktur mit einer Wolfram–Kohlenstoff-Bindung. 2a last sich mit uberschussiger MCPBA nur in geringen Ausbeuten zum Sulfon (η5-C5H5)W(CO)3 CH2SO2C6H5 (3a) oxidieren, wahrend 2b nicht reagiert. Deprotonierungsversuche am α-Kohlenstoff von 2a und 2b verliefen ergebnislos. Functionalized Transition Metal Alkyls, II. – Synthesis, Crystal Structure, and Reactivity of (η5-C5H5)W(CO)3CH2S(O)C6H5, an α-Metallated Sulfoxide The organometallic sulfides (η5-C5R5)W(CO)3 CH2SC6H5 (R = H: 1a; R = Me: 1b) react with m-chloroperbenzoic acid (MCPBA) to yield the sulfoxides (η5-C5R5)W(CO)3 CH2S(O)C6H5 (2a, b). A crystal structure determination by X-ray diffraction of 2a shows a structure with a tungsten–carbon bond. 2a reacts with excess MCPBA to form the sulfone (η5-C5H5)W(CO)3 CH2SO2C6H5 (3a) in poor yield, but the same reaction failed for 2b. Attempts to deprotonate the α-carbon atom of 2a and 2b were unsuccessful.

Pyrolysis of H3Os3(CO)9(μ3-CC6H5) (1) in a sealed glass tube at 220°C gives the known methylbenzyne complex H2Os3(CO)9(μ3,η 2-C6H3CH3) (2), previously prepared from Os3(CO)10(NCCH3)2 and toluene. Similar pyrolysis (220°C) of 2 either as a solid or in tridecane solution shows significant conversion to 1, demonstrating reversibility. Pyrolysis of H3Os3(CO)9(μ3-CC6D5) (1-d5) provides 2, which shows scrambling of the deuterium atoms into all sites by 1H NMR. However, pyrolysis of a mixture of 1 and D2Os3(CO)9(μ3,η2-C6D3CD3) (2-d8) gives 2 which is also just partially deuterated in all proton sites. Thus, intermolecular hydrogen/deuterium exchange accompanies the benzylidyne/methylbenzene interconversion.

The gold compound Ph3PAu CHPh SO2-t-Bu is obtained from the reaction of (PhCH SO2-t-Bu)−Li+ with Ph3PAuCl. A crystal structure determination shows that gold is coordinated only at the sulfone's benzylic carbon atom. In contrast, α-sulfonyl-lithium compounds show coordination of the metal exclusively at the sulfonyl oxygen atoms.

Linear und trigonal-planar konfigurierte Zinn-Atome aufweisende Organomangan-Komplexe sind nach zwei Methoden darstellbar: Schrittweise Behandlung des Komplexes (η5-C5H4CH3)-Mn(CO)2(THF) (1a) mit Zinn(II)-chlorid und Zink-Staub fuhrt ebenso zum Zinn-Komplex (μ3-Sn)[(η5-C5H4CH3)Mn(CO)2]3 (2a) wie die Umsetzung von 1a mit Monostannan, SnH4. Der Pentamethylcyclopentadienyl-Komplex 1b ergibt analog die Derivate (μ3-Sn)[(η5-C5Me5)(CO)2]3 (2b) und (μ-Sn)[(η5-C5Me5)Mn-(CO)2]2 (3b). Formal weist der μ3-Sn-Komplex 2a zwei MnSn-Einfachbindungen und eine MnSn-Doppelbindung auf (Einkristall-Rontgenstrukturanalyse). Multiple Bonds Between Main-Group Elements and Transition Metals, LIX. – Bridging Tin Atoms in Organomanganese Complexes. Formation, Structures, and Reactivity of Manganese–Tin Multiple Bonds. Organomanganese complexes with tin atoms in linear and trigonal planar coordination environments are accessible by means of two different synthetic methods. Sequential treatment of the complex (η5-C5H4CH3)Mn(CO)2(THF) (1a) with tin(II) chloride and zinc dust yields (μ3-Sn)[(η5-C5H4CH3)Mn(CO)2]3 (2a); 2a is also formed from 1a and monostannane, SnH4. The pentamethylcyclopentadienyl derivative 1b yields analogously the two compounds (μ3-Sn)[(η5-C5Me5)Mn(CO)2]3 (2b) and (μ-Sn)[η5-C5Me5)Mn(CO)2]2 (3b). 2a formally contains two MnSn single bonds and a MnSn double bond (X-ray diffraction study).

Selenium acts as a bridging ligand between two iron atoms in the novel complex (μ-Se)(η 5 -C 5 H 5 )Fe(CO) 2 ] 2 ( 1 ), obtained in 60% yield from Na + [(η 5 -C 5 H 5 )Fe(CO) 2 ] and Se 2 Cl 2 . 1 displays nucleophilic reactivity towards protic acids (e.g., HBF 4 ·OEt 2 ) and methyl triflate, CF 3 SO 3 CH 3 , thus giving the protonated and methylated ionic species [(μ-SeR)(η 5 -C 5 H 5 )Fe(CO) 2 2 ] + (R = H: 2a , BF 4 salt; R = CH 3 : 2b , PF 6 salt) in quantitative yields. Rapid deprotonation of 2a occurs in the presence of bases such as diethylamine. Analogous protonation and methylation reactions have been observed with the tellurium complex (μ-Te)[(η 5 -C 5 H 5 )Cr(CO) 3 ] 2 ( 3 ); the ionic compounds [(μ-TeH)(η 5 -C 5 H 5 )Cr(CO) 3 2 ]BF 4 ( 4a ) and [(μ-TeCH 3 ) (η 5 -C 5 H 5 )Cr(CO) 3 2 ]PF 6 ( 4a ), respectively, are obtained. In contrast, the electron-deficient tellurium ligand of the manganese complex (μ 3 -Te)[(η 5 -C 5 H 5 )Mn(CO) 2 ] 3 ( 5 ) is neither attacked by Bronsted acids nor by electrophilic methylating agents (e.g., CF 3 SO 3 CH 3 ) but is rather methylated by methyllithium to give the anionic species [(μ 3 -TeCH 3 )η 5 -C 5 H 5 )Mn(CO) 2 3 ] − that can be isolated pure as the PPN + salt 6 .

Selenium dioxide and osmium tetroxide are effective reagents and catalysts for olefin oxidation, although, owing to their toxicity, reservations remain as to their applicability.[1] We are therefore seeking more easily handled metal oxides that are soluble in organic solvents and that are as effective as osmium tetroxide in carrying out stereospecific cis hydroxylation of olefins. The rhenium(VII) oxide 1, which has meanwhile become readily accessible, is a favorable candidate.[2]

Ethyne reacts with [Mo2(CO)4(η-C5Me5)2] under u.v. irradiation to yield [Mo2(CO)4(µ-η1,η2-CCH2)(η-C5Me5)2], containing vinylidene bound side-on to the dimolybdenum centre as a four-electron ligand; this new species undergoes thermal isomerisation to µ-ethyne, reacts with diazomethane to give µ-allene, and is step-wise protonated to afford µ-vinyl then µ-ethylidene.

Synthesis and studies of alkylidynetrimetal clusters have received special notice in recent years because these clusters may be related to species occurring on metal surfaces during homogeneous catalysis. The synthesis and NMR characterization of the first fluoromethylidynetriosmium cluster together with a /sup 13/C NMR comparison of analogous substituted methylidynetriosmium and tricobalt clusters are presented herein. 13 refs., 1 fig., 1 tab.