Evan P. Kyba

A novel synthesis of 1,2-diphosphorylbenzenes

Abstract Synthesis of phosphorylchloroacetylenes, diphosphorylacetylenes and the Diels-Alder reactions of the latter to produce o -diphosphorylbenzenes are described.

Phosphoryl-substituted 1-azadienes for use in intra-molecular diels-alder cyclizations

Abstract The preparation and isolation of 2-(diethoxyphosphoryl)-1-azadienes and their use in the formation of functionalized quinolizidine and indolizidine ring systems via an intramolecular Diels-Alder reaction is described.

Addition of amine nucleophiles to diphosphorylalkynes. The chemistry of the derived enamines

Abstract Amine nucleophiles bearing at least one hydrogen substituent add across tetraethyl ethynyldiphosphonate to give enamine derivatives, one of which (derived from cyclohexylamine) has been evaluated as an imine anion precursor in alkylation and Wittig-Horner-Emmons types of reactions.

Linked bis(μ-phosphido) and related ligands for metallic clusters: IX. Heterogeneous hydrogenation of 1-octene using phosphidostabilized di- and triruthenium metal clusters on a silica support. A case for an intact supported cluster as a catalyst

Abstract The homogeneous and heterogeneous hydrogenation of 1-octene was studied using phosphido-stabilized ruthenium clusters as catalysts. All four phosphido-stabilized ruthenium clusters Ru2(CO)6[1,2-(μ-PPh)2C6H4] (1), Ru3(CO)6[1,2-(μ-PPh)2C6H4]2 (2), Ru2(CO)6[1,2-(μ-PtBu2C6H4] (3), and Ru3(CO)6[1,2-(μ-PtBu2C6H4]2 (4) were found to be active hydrogenation and isomerization catalyst precursors, but no hydrogenolysis was observed even at elevated temperatures. The polar environment of the Cab-o-sil (silica) support activated the triruthenium cluster 2 in comparison with the homogeneous hydrogenation of 1-octene. Addition of a Lewis acid (Et2O:BF3) to the homogeneous hydrogenation of 1-octene resulted in modestly higher catalytic activity of 2. Compound 2 was quantitatively recovered from the Cab-o-sil support intact after hydrogenating 1-octene at 140°C for several hours.

Influence of Steric Bulk on the Relative Stability and Interchangeability of the Various Oxidation States for Nickel Complexed with 1,2-Bis(Dialkylphosphino)Benzene

Abstract The reduction potentials and electrochemical reversibilities of a series of nickel complexes of 1,2-bis(dialkylphosphino)benzene are sensitive to the steric bulk of the alkyl substituents. With very large ligands, electroreduction is accompanied by rapid secondary chemical reaction, and spectroscopic evidence for the intermediacy of a coordinatively unsaturated species is presented. The potentials required for electrooxidation of these complexes are shifted to more positive potentials by increasing bulk of the alkyl substituents on the bisphosphino ligands.

Linked Bis(μ-Phosphido) and Related Ligands for Metallic Clusters. 2. Reaction of 1,2,3-Triphenyl-1,2,3-Triphosphaindane with Nonacarbonyldiiron

Abstract The reaction of 1,2,3-triphenyl-1,2,3-triphosphaindane with nonacarbonyldiiron in benzene at 80 °C gives rise to a mixture of at least eight components, five of which have been isolated and characterized. Three of these are P3Fe3 species, of which two have been unambiguously identified by single crystal x-ray crystallography.

Linked bis(μ-phosphido) and related ligands for metallic clusters

Abstract Reaction of [μ-1,2-phenylenebis(phenyl- or t-butyl-phosphido)-P,P](μ-carbonyl)-bis(η5-cyclopentadienyl)dimolydenum(MoMo) with nonacarbonyldiiron gave 46-electron Me2Fe complexes, which were shown by X-ray crystallography in one case to have an open trimetalla structure (phenylphosphido), and in the other, a triangulo structure (t-butylphosphido). The open triametalla species is fluxional as a result of metal-to-metal migrations, whereas the triangulo cluster is nonfluxional.

Preliminary communicationLinked bis(μ-phosphido) and related ligands for metallic clusters: VI. Incorporation of (CO)4Fe into complexes which contain a bis(μ-phosphido)-supported MoMo functionality to give unsaturated 46-electron Mo2Fe clusters☆

Abstract Reaction of [μ-1,2-phenylenebis(phenyl- or t-butyl-phosphido)-P,P](μ-carbonyl)-bis(η5-cyclopentadienyl)dimolydenum(MoMo) with nonacarbonyldiiron gave 46-electron Me2Fe complexes, which were shown by X-ray crystallography in one case to have an open trimetalla structure (phenylphosphido), and in the other, a triangulo structure (t-butylphosphido). The open triametalla species is fluxional as a result of metal-to-metal migrations, whereas the triangulo cluster is nonfluxional.

Linked bis(μ-phosphido) and related ligands for metallic clusters: VI. Incorporation of (CO)4Fe into complexes which contain a bis(μ-phosphido)-supported MoMo functionality to give unsaturated 46-electron Mo2Fe clusters☆

Abstract Reaction of [μ-1,2-phenylenebis(phenyl- or t-butyl-phosphido)-P,P](μ-carbonyl)-bis(η5-cyclopentadienyl)dimolydenum(MoMo) with nonacarbonyldiiron gave 46-electron Me2Fe complexes, which were shown by X-ray crystallography in one case to have an open trimetalla structure (phenylphosphido), and in the other, a triangulo structure (t-butylphosphido). The open triametalla species is fluxional as a result of metal-to-metal migrations, whereas the triangulo cluster is nonfluxional.

Hydrogenolysis of cyclo-octane and cyclo-octene on supported Fischer–Tropsch catalysts. Cyclic vs. noncyclic selectivity

Hydrogenolysis of cyclo-octane or cyclo-octene over silica-supported ruthenium, nickel, and cobalt catalysts gives rise to n-alkanes and cycloalkanes (C5–C7); ruthenium strongly favours n-alkanes, cobalt strongly facilitates cycloalkane formation, and nickel is intermediate in selectivity.