One of the remaining “grand challenges” in chemistry is the development of a next generation, less expensive, cleaner process that can allow the vast reserves of methane from natural gas to augment or replace oil as the source of fuels and chemicals. Homogeneous (gas/liquid) systems that convert methane to functionalized products with emphasis on reports after 1995 are reviewed. Gas/solid, bioinorganic, biological, and reaction systems that do not specifically involve methane functionalization are excluded. The various reports are grouped under the main element involved in the direct reactions with methane. Central to the review is classification of the various reports into 12 categories based on both practical considerations and the mechanisms of the elementary reactions with methane. Practical considerations are based on whether or not the system reported can directly or indirectly utilize O2 as the only net coreactant based only on thermodynamic potentials. Mechanistic classifications are based on whet...

Homogeneous Functionalization of Methane

Organometallic intramolecular-coordination compounds containing a π-allyl donor ligand

The Gas‐Phase Chemistry of Transition‐Metal Ions with Organic Molecules

Rh-mediated polymerization of carbenes gives access to new highly substituted and stereoregular polymers. While this reaction is of interest for the synthesis of syndiotactic polymers that are functionalized at every carbon atom of the polymer backbone, the catalyst activation, chain-initiation, and chain-termination processes were so far poorly understood. In this publication we present new information about these processes on the basis of detailed end-group analyses, dilution-kinetic studies, and a comparison of the activity of well-defined catalysts containing a preformed Rh–C bond. All data point toward complex catalyst activation processes under the applied reaction conditions. The use of well-defined RhI(cod)-alkyl, aryl, and allyl complexes does not lead to better initiation efficiencies or higher polymer yields. MALDI-ToF MS of the oligomeric fractions indicates that during the incubation time of the reaction, the precatalysts are first transformed into oligomer forming species with a suppressed t...

Rh-Mediated Carbene Polymerization: from Multistep Catalyst Activation to Alcohol-Mediated Chain-Transfer

20 – Non-rigidity in Organometallic Compounds

Unter geeigneten Mesbedingungen treten im Massenspektrum von C5H5NiNO zweikernige Sekundar-Ionen auf. In Gegenwart verschiedener σ- oder π-Donatoren L finden zusatzliche Ion-Molekul-Reaktionen statt unter Bildung der Ionen C5H5NiL+ sowie davon abgeleiteter Fragmente. Selbst mit inerten Verbindungen wie n-Hexan oder Cyclohexan werden Reaktionen beobachtet, wobei die Ionen C5H5Ni(Hexen)+ bzw. C5H5Ni(Cyclohexen)+ entstehen. Die relativen Wirkungsquerschnitte der Ion-Molekul-Reaktionen sowie die Auftrittspotentiale einiger Sekundar-Ionen wurden gemessen und interpretiert.



Ion-Molecule Reactions of Organometallic Complexes, IV. Ion-Molecule Reactions of (Cyclopentadienyl)nitrosylnickel with σ- and π-Donors in the Gas Phase



Under suitable measuring conditions binuclear secondary ions appear in the mass spectrum of C5H5NiNO. If several σ- or π-donor molecules L are present, additional ion-molecule reactions occur with formation of the ions C5H5NiL+ as well as of fragments derived from these. Even with inert compounds like n-hexane or cyclohexane reactions are observed by which the ions C5H5Ni(hexene)+ and C5H5Ni(cyclohexene)+ respectively are formed. The relative cross-sections of the ion-molecule reactions as well as the appearance potentials of several secondary ions have been measured and interpreted.

Ion-Molekül-Reaktionen metallorganischer Komplexe, IV. Ion-Molekül-Reaktionen von (Cyclopentadienyl)nitrosylnickel mit σ- und π-Donatoren in der Gasphase

Durch Umsetzung von [LRhCl]2(L = 1,5-Cyclooctadien, 1,3,-Cycloheptadien, Norbornadien) und von[C5 (CH3) 5RhCl2]2miti-C3H7MgBr in Gegenwart cyclischer Oligoolefine unterschiedlicher Ringgrose wurden neutrale π-Komplexe des Typs [(Dien)RhI(Allyl)] und [(Dien)RhI(Dienyl)] synthetisiert, in denen das Zentralmetall eine 16- bzw. 18-Elektronen-Valenzschale erreicht. Die spektroskopischen und einige chemischen Eigenschaften der Verbindungen werden beschrieben. Im Gegensatz zu den 16-Elektronen-Komplexen zeigen einige 18-Elektronen-Verbindungen ein fluktuierendes Verhalten.



Synthesis and Properties of Normal π-Cycloolefin Rhodium Complexes



By reactions of [LRhCl]2, (L = 1,5-cycloheptadiene, 1,3-cycloheptadiene, norbornadiene) and of [C5(CH3)5RhCl2]2 with i-C3H7MgBr in the presence of cyclic oligoolefins with different ring size neutral π-complexes of the type [(diene)RhI(allyl)] und [(diene)RhI(dienyl)] were synthesized in which the central metal achieves a 16- and 18-electron valence shell, respectively. The spectroscopic and several chemical properties of the compounds are described. In contrast to the 16-electron complexes some of the 18-electron compounds show a fluxional behaviour.

Synthese und Eigenschaften neutraler π‐Cycloolefin‐Rhodium‐Komplexe

Last man unter geeigneten Mesbedingungen C5H5V(CO)4, C5H5Mn(CO)3 oder C5H5Co(CO)2 zusammen mit einer Vielzahl von σ- oder π-Donatoren L in die Ionenquelle eines Massenspektrometers einstromen, so werden vorwiegend nach der Gleichung C5H5M(CO)n++ L C5H5ML+ + n CO Sekundar-Ionen C5H5ML+ und davon abgeleitete Fragment-Ionen gebildet. Der Ablauf und die relativen Wirkungsquerschnitte der Ion-Molekul-Reaktionen sowie die Art der Fragment-Ionen werden durch die Liganden L und durch das Metall M bestimmt.



Ion-Molecule Reactions of Organometallic Complexes, V. Ion-Molecule Reactions of Carbonyl(cyclopentadienyl)metal Complexes with σ- and π-Donors in the Gas Phase



When under suitable measuring conditions C5H5V(CO)4, C5H5Mn(CO)3, or C5H5Co(CO)2 together with a variety of σ- and π-donor molecules L are introduced into the ion source of a mass spectrometer, secondary ions C5H5ML+ and fragment ions derived therefrom are formed according to the equation C5H5M(CO)n+ + L C5H5ML+ + n CO. The course and the relative cross-sections of the ion-molecule reactions as well as the nature of the fragment ions depend on the ligand molecules L and on the metal atom M.

Ion‐Molekül‐Reaktionen metallorganischer Komplexe, V. Ion‐Molekül‐Reaktionen von Carbonyl(cyclopentadienyl)metall‐Komplexen mit σ‐ und π‐Donatoren in der Gasphase

Werner Goll

Papers

Ion-Molekül-Reaktionen metallorganischer Komplexe, IV. Ion-Molekül-Reaktionen von (Cyclopentadienyl)nitrosylnickel mit σ- und π-Donatoren in der Gasphase

Synthese und Eigenschaften neutraler π‐Cycloolefin‐Rhodium‐Komplexe

Ion‐Molekül‐Reaktionen metallorganischer Komplexe, V. Ion‐Molekül‐Reaktionen von Carbonyl(cyclopentadienyl)metall‐Komplexen mit σ‐ und π‐Donatoren in der Gasphase