P. C. Reeves

Transmission of substituent effects in anilinetricarbonylchromium compounds

The acidities of several substituted phenoltricarbonylchromium compounds have been determined in 50% ethanol. A plot of pKa values versus Hammett substituent constants indicates that no distortion of substituent effects occurs upon complexation of an aromatic system to the tricarbonylchromium moiety.

Reaction of pentadienyliron tricarbonyl cations with hydride donors

Abstract A series of pentadienyliron tricarbonyl cations has been prepared and reacted with the hydride ion donors sodium borohydride, sodium cyanoborohydride, and lithium triethylborohydride in order to determine steric and electronic effects in these reduction reactions. Sodium cyanoborohydride yields products of retained configuration whereas lithium triethylborohydride yields dieneiron tricarbonyl compounds of inverted configuration. Kinetic and thermodynamic considerations are used to account for these results.

Reactions of unsymmetrically substituted pentadienyliron tricarbonyl cations with water

Abstract The reactions of unsymmetrically-substituted pentadienyliron tricarbonyl cations with water have been studied in order to learn more about the relative importance of steric and electronic factors in determining the position of nucleophilic attack.

A 13C nuclear magnetic resonance study of cyclobutadieneirontricarbonyl-substituted carbonium ions

Abstract The 13 C NMR spectra of (hydroxymethyl)-, (α-hydroxyethyl)- and (α-hydroxybenzyl)cyclobutadieneiron tricarbonyl (in CDCl 3 ) and of their derived carbonium ions (in concentrated H 2 SO 4 ) are reported. The data suggest extensive donation of electron density from the metal, via the cyclobutadiene unit, to the exocyclic, electron-deficient carbon atom, thus giving highly stabilized carbonium ions.

Phase transfer catalysts anchored to polystyrene

Abstract Quarternary phosphonium and ammonium salts attached to polystyrene resins by short (2 - 3 atom) carbon chains are highly active phase transfer catalysts for a variety of nucleophilic substitution reactions.

Cyclobutadieneiron tricarbonyl carboxylic acids: Synthesis and acidity

Abstract Two carboxylic acid derivatives of the cyclobutadieneiron tricarbonyl (I) system have been synthesized and their p K a values determined. It appears that I tends to be electron withdrawing by induction and electron releasing by resonance.

Photochemical reactions of 1,2-dimethylcyclobutadieneiron tricarbonyl with various acetylenes

Abstract The photochemical reactions of 1,2-dimethylcyclobutadieneiron tricarbonyl with a variety of acetylenes have been studied. Benzenoid compounds generally are obtained. In particular, irradiation of the 1,2-dimethyl complex with acetylene yields o-xylene and p-xylene. Reaction with propyne produces 1,2,3- and 1,2,4-trimethylbenzene while 2-butyne forms 1,2,3,4- and 1,2,4,5-tetramethylbenzene. Several possible reaction mechanisms are presented and evaluated in light of the observed product distributions.

General Synthetic Route to Monosubstituted Cycloheptadienes from Organometallic Compounds

Abstract An examination of the literature reveals that only a limited number of monosubstituted cycloheptadiene compounds have been reported. An obvious synthetic route to 5-substituted -1, 3-cycloheptadiene derivatives would be the reaction of nucleophiles with the cycloheptadienyl cation, but this pathway is generally unsuccessful due to the limited stability of the cation. On the other hand, the iron tricarbonyl complex of this cation shows remarkable stability1 and an ability to react with nucleophiles2. If the -Fe(CO)3 group could be removed easily, a facile route to this family of organic compounds would be available. This work reports our investigation of the range of nucleophiles that can be utilized and the oxidizing agents that can remove efficiently the -Fe(CO)3 group.

Substituent effects in the tricarbonylcyclobutadieneiron system

Proton n.m.r. spectra of twenty-one substituted tricarbonylcyclobutadieneiron complexes in deuteriochloroform reveal that a substituent modifies electron density at the ring positions adjacent to it in much the same fashion as a substituent in the benzene system. A substituent has a significant influence on electron density at the carbon atom directly across the ring.

TRANSMISSION VON SUBSTITUENTENEFFEKTEN IN PHENOLTRICARBONYLCHROM-VERBINDUNGEN

Die Komplexe (Ia) und (Ib) wurden mit 61 bzw. 30% Ausbeute aus dem Phenol und Hexacarbonylchrom und die Verbindung (I) nach Literaturmethoden dargestellt.