Search

Reversible coordination networks are developed by compounding diphenylphosphinite telechelic polytetrahydrofuran with [[RhCl(COD)].sub.2] or [[IrCl(COD)].sub.2] in chloroform. Findings reveal that both systems result in stable gels at concentrations above 50 and 30 g/L for the rhodium(I) and iridium(I) networks.

A series of complexes of the type Cp*IrCl2(NHC) were synthesized with the aim of evaluating the capabilities in C-H activation, specifically in H/D exchange of a wide range of organic molecules. The Cp*IrCl2(NHC) catalysts are tested in the deuteration of organic molecules, using CD3OD as deuterium source.

A series of heteroleptic Ir(III) metal complexes bearing two N-phenyl-substituted pyrazoles and one 2-pyridyl pyrazole ligands are synthesized and characterized to attain highly efficient, room temperature blue phosphorescence. The results on the basis of steady-state, relaxation dynamics, and theoretical approaches, lead to a conclusion that the weakening of iridium metal-ligand bonding strength in the T1 state plays a crucial role for the fast radiationless deactivation.

The synthesis and structural peculiarities of iridium complexes exhibiting a novel eta(super 1)-N,eta(super 2)-C,C-binding interaction between the pyridinyl-functionalized fulvene ligand and the metal center are described. The efforts to prepare cyclometalated Ir and Pt complexes with ligands containing smaller pi systems than those of the phenyl-pyridines are still underway.

The design of homogeneous catalysts based on Ir and other late transition metal complexes using O-donor ligands like acetylacetonate (aca), tropolone, aryloxides, catechols, hydroxyaetophenone to stabilize the complexes to the reaction conditions needed for generating functionalized products is discussed. The outcome of the studies helps to utilize, design new, more effective, thermally protic-and oxidant-stable O-donor catalysts for hydrocarbon conversion.

The synthesis and photophysical characterization of a series of (N,C(super 2')-(2-para-tolylpyridyl)2Ir(LL') [tpy)2Ir(LL')] (LL' = 2,4-pentanedionato (acac), bis(pyrazolyl)borate ligands and their analogues, diphosphine chelates and tert-butylisocyanide (CN-t-Bu) are reported. The electrochemical and photophysical properties of the (typ)2Ir(LL') complexes are discussed in detail.

Two-electron mixed-valence di-iridium alkyl complexes react with hydrogen in a cascade reaction to produce a trihydride and alkane. The overall reaction sequence depends critically on hydrogen migration to and from a bridging position.

The synthesis of new ligand systems incorporating two and three 4,4'-bipyridine units are described. These complexes were fully characterized by X-ray structural analysis.

A mechanistic study of the stoichiometric and catalytic H/D exchange reactions involving cationic iridium complexes is presented. The catalytic H/D exchange reaction is not catalyzed by simple H(super +) transfer, but instead proceeds by a reversible C-H bond activation mechanism.

Reversible dihydrogen uptake by a two-electron mixed-valence di-iridium complex is examined with nonlocal density-functional calculations. The investigation establishes a ligand-design criterion for attaining cooperative bimetallic reactivity, namely, that the supporting ligand framework is mechanically flexible enough to accommodate the nuclear reorganizations that accompany substrate activation.

Highly efficient, selective, and general method, that permits the preparation of meridional homo- and heteroleptic mer tris-cyclometalated iridium complexes is developed. These materials enable further elucidation of the electronic structure of cyclometalated iridium complexes through comparison of a wider range of emissive ligands in specific environments.

The molecular structures, physical properties, electronics structures, and thermochromism of the cluster complexes, which indicate a novel mode of metalladithiolene bonding to metals, are presented. These cluster complexes showed thermochromism with decrease in temperature.

The reactions of Rh4(CO)12 and Ir4(CO)12 with Ph3SnH yielded the Rh-Sn and Ir-Sn cluster complexes M3(CO)6(u-SnPh2)3-(SnPh3)3, (M=Rh) and (M = Ir). Both compounds contained triangular M3 clusters with three bridging SnPh2, three terminal SnPh3 ligands, and two triply bridging SnPh ligands.

NMR and several other techniques are employed to explain the properties and applications of the various iridium pincer complexes. The mechanisms and barriers involved in the interconversion taking place between the tetrahydride and dihydrogen/dihydride species are also studied.

The synthesis, as well as the characterization of the numerous electrochemiluminescent functionalizable cyclometalated thiophene-based iridium(III) complexes are explained. The various effects of the different substituents on the cyclic voltammetry behavior of the compounds are also explained.

The application of the various Boc groups as the protectors and directors of the Ir-catalyzed C-H borylation of the various heterocycles is discussed. The results prove that thermolysis can also be employed for the removal of the Boc group.

The article discusses the mechanisms involved in the carbon-carbon bond formation reaction, which is shown to be based on the carbon-hydrogen bond functionalization of the unactivated alkenes. The cyclic alkenes are shown to play an extremely significant role in determining the selectivity of the discussed bond functionalization.

Mono- and 2,2E-disubstituted terminal alkenes are isomerized into the more stable internal (Z)- and (E)-alkenes by treating them with catalytic amounts of [[(allyl)PdCl].sub.2] or [[(allyl)NiBr].sub.2], a triarylphosphine, and silver triflate at room temperature. The reaction is tolerant to a wide variety of functional groups including other reactive olefins and unlike the more reactive Ir catalysts, monosubstituted alkenes has given almost exclusively the 2-alkenes.

Bi-, tri-, and tetracyclic isoquinoline salts are prepared at room temperature from readily available starting materials after three reaction steps. The isoquinoline salts are prepared from readily available starting materials by using one-pot procedures, thus providing a novel, efficient method for metal-mediated synthesis of heterocycles.

The synthesis of a series of five-coordinate [d.sup.6] iridium complexes, ([super tBu]PCP)Ir(R)(R'), where R and R' are Me, Ph and (phenyl-substituted) vinlyl and alkynyl groups, and the absolute rate of C-C elimination are described. The results have not supported the hypothesis that the degree of directionality of the carbon-based orbital used for bonding to iridium has played a vital role in this system in determining the barrier to reductive elimination.

The structure of (tBuPOCOP)Ir[H.sub.2](B[H.sub.3]) determined from neutron diffraction data has a B-H [sigma]-bond to iridium with an elongated B-H bond distance of 1.45(5) Angstrom. The structure of borane complex is determined by X-ray diffraction and consists of the (tBuPOCOP)Ir core with a [sigma]-bound pinacol borane ligand in an approximately square planar complex.

A new technique was developed for covalent tethering via a 'hetero' cyclometallating ligand, of heteroleptic tris-cyclometallated iridium(III) complexes to polymeric supports for application in light-emitting diode technologies is reported. The isomerization process involved alcohol-catalyzed synthesis and characterization of a number of heteroleptic tris-cyclometallated iridium(III), [Ir[(C,N).sub.2](C',N')] complexes with formation of [Ir[(C,N).sub.2]OR] as intermediate complex.

The preparation of a heterodinuclear [Al.sup.III][Ir.sup.III] complex from the molecular coupling of a salen-based aluminum complex as a host and a phenylpyridine-based ionic iridium complex as a phosphorescent emitter is reported. The heterodinuclear complex showed bright-orange light emission when used as an active layer in host-dopant assembly organic light-emitting diodes based on a solution process.

A second type of silylene complex that has catalyzed the highly anti-Markovnikov hydroslation of olefins by the same type of direct Si-H addition mechanism is described. The results have shown that the transition metal fragment supporting the silylene ligand has displayed strong steric influences over the reactivity toward the olefin substrate.

The synthesis, structural characterization and the ligand replacement reactions of the gem-dithiolato-bridged rhodium and iridium complexes are discussed. The catalytic activity of the system is shown to be highly affected by the gem-dithiolato ligand.

The generation of well-dispersed iridium(0) nanoparticles by the reduction of the precursor, hydridoiridium carborane is explained. The obtained nanoparticles are shown to be widely used as catalysts for the arylborylation process, producing boric acid.

The application of bis-terpyridine (tpy) metal complexes, particularly, iridium terpyridine complexes, as assembling and functional units in multicomponent arrays for achieving charge separation. The analysis demonstrates how the performances of an artificial photofunctional array can be modeled by a careful design assisted by a detailed knowledge of the systems.

A tripod system is described for biotin-avidin assays, consisting of an energy acceptor, an energy donor and biotin. The neutral sensing system for biotin-avidin assays has offered good sensitivity due to intramolecular energy transfer and increased hydrophobicity associated with the avidin binding site and neutral probe.

The synthesis and characterization of highly phosphorescent blue-light-emitting anionic iridium complexes are described. Density functional theory (DFT) and time dependent-DFT calculations are performed on the ground and excited states of these complexes in order to provide insights into the structural electronic and optical properties of these systems.

Iridium catalysts with chiral P, N ligands emerged as a new class of highly efficient catalysts for asymmetric hydrogenation. This new class catalyst can be used to hydrogenate the variety of substrates for which no suitable catalysts were available before.

The synthesis of bimetallic [[(ppy)2Ir(mu-L)Ir(ppy)2].sup.2+] complexes is reported as a mixture of three stereoisomers. The electronic absorption and the luminescence properties of the three compounds are investigated.

The report explains the synthesis and electrophosphorescence of a new deep red phosphorescent Ir(III) complex, which is commonly used in polymer light-emitting diodes. These substances can easily solubalize arylsilyl-substituted ligands, exhibiting excellent phase homogeneity.

Allylic amines are formed upon hydrogenation of 1, 2-dialkyl-substituted alkynes in the presence of N-arylsulfonyl aldimines. Studies reveal that organometallics arising transiently under hydrogenation conditions maybe coupled to conventional electrophiles, thus circumventing use of preformed organometallic reagents as nonstabilized carbanion equivalents in certain carbonyl and imine addition processes.

Density functional theory is used for studying phase diagrams for skutterudite solid solutions made by alloying at the Co site of Co[Sb.sub.3] skutterudite structure. The analysis has shown that [Ir.sub.x][Rh.sub.1-x][Sb.sub.3] is a compound with ordered structure rather than a random solid solution.

The electrospray ionization mass spectrometry (ESI-MS) and tandem mass spectrometry (ESI-MS/MS) investigation of a novel family of iridium complexes formed by nitroso ligands coordinated to [[IrC[l.sub.5].sup.2-] is reported.