There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Pick your Pd partners: A number of catalytic systems have been developed for palladium-catalyzed CH activation/CC bond formation. Recent studies concerning the palladium(II)-catalyzed coupling of CH bonds with organometallic reagents through a PdII/Pd0 catalytic cycle are discussed (see scheme), and the versatility and practicality of this new mode of catalysis are presented. Unaddressed questions and the potential for development in the field are also addressed.

In the past decade, palladium-catalyzed CH activation/CC bond-forming reactions have emerged as promising new catalytic transformations; however, development in this field is still at an early stage compared to the state of the art in cross-coupling reactions using aryl and alkyl halides. This Review begins with a brief introduction of four extensively investigated modes of catalysis for forming CC bonds from CH bonds: PdII/Pd0, PdII/PdIV, Pd0/PdII/PdIV, and Pd0/PdII catalysis. A more detailed discussion is then directed towards the recent development of palladium(II)-catalyzed coupling of CH bonds with organometallic reagents through a PdII/Pd0 catalytic cycle. Despite the progress made to date, improving the versatility and practicality of this new reaction remains a tremendous challenge.

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Palladium(II)-catalyzed C-H activation/C-C cross-coupling reactions: versatility and practicality.

1. Advantages of Chemical Redox Agents 878 2. Disadvantages of Chemical Redox Agents 879 C. Potentials in Nonaqueous Solvents 879 D. Reversible vs Irreversible ET Reagents 879 E. Categorization of Reagent Strength 881 II. Oxidants 881 A. Inorganic 881 1. Metal and Metal Complex Oxidants 881 2. Main Group Oxidants 887 B. Organic 891 1. Radical Cations 891 2. Carbocations 893 3. Cyanocarbons and Related Electron-Rich Compounds 894

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Chemical Redox Agents for Organometallic Chemistry

Self-Assembly of Discrete Cyclic Nanostructures Mediated by Transition Metals

The new ONIOM (our own n-layered integrated molecular orbital and molecular mechanics) approach has been proposed and shown to be successful in reproducing benchmark calculations and experimental results. ONIOM3, a three-layered version, divides a system into an active part treated at a very high level of ab initio molecular orbital theory like CCSD(T), a semiactive part that includes important electronic contributions and is treated at the HF or MP2 level, and a nonactive part that is handled using force field approaches. The three-layered scheme allows us to study a larger system more accurately than the previously proposed two-layered schemes IMOMO, which can treat a medium size system very accurately, and IMOMM, which can handle a very large system with modest accuracy. This three-layered scheme has been applied to activation barriers for the Diels−Alder reaction of acrolein + isoprene, acrolein + 2-tert-butyl-1,3-butadiene, and ethylene + 1,4-di-tert-butyl-1,3-butadiene. In general, the results for b...

ONIOM: A Multilayered Integrated MO + MM Method for Geometry Optimizations and Single Point Energy Predictions. A Test for Diels−Alder Reactions and Pt(P(t-Bu)3)2 + H2 Oxidative Addition

The title complex has been prepared in 36% yield by reaction of [NBu 4 ] 2 [trans-Pt(C 6 Cl 5 ) 2 Cl 2 ] with NOClO 4 (1:1) in CH 2 Cl 2 . The anion exhibits an almost tetragonal-pyramidal geometry (X-ray analysis), the platinum atom being virtually located in the basal plane and the NO ligand occupying the apical position. The Pt-N-O unit is bent [119.5(8) o ]

Synthesis and Structural Characterization of the Bent Nitrosyl Organometallic Complex [NBu4][Pt(C6Cl5)2Cl2(NO)]

(NBu4) Sn{Pt(μ-Cl)(C6F5)2}3ein ungewöhnlicher Cluster mit drei PtII SnII-Bindungen†

Reactivity of cis-[Pd4(μ-X)4μ-C(C6F5)NMe4] (X Cl, Br, 1) towards neutral bidentate ligands

Synthesis and reactivity of phosphanido bridged 1,1′-bis(diphenylphosphino)ferrocene complexes [(RF)2Pt(μ-PPh2)2M(dppf)] [M = Pt, Pd]

Complexes of the general formula PdL2(π-CS2) (L = PPh3 PEtPh2; PCy3 (tricyclohexyphosphine); L2 = L-L = dpe (1,2-bis (diphenylphosph ino)ethane dpb(1,4-bis(d iphenylphosphino) butane, b ipy (2,2′-bipyr id ine) or phen (1,10-phenanthroline)) have been prepared by the reaction of Pd2(dba)3.CHCl3 (dba = dibenzylideneacetone) with stoicheiometric amounts of the ligands L or L-L and CS2. The novel complexes are characterized by their IR spectra.

Juan Forniés

Papers

Synthesis and Structural Characterization of the Bent Nitrosyl Organometallic Complex [NBu4][Pt(C6Cl5)2Cl2(NO)]

(NBu4) Sn{Pt(μ-Cl)(C6F5)2}3ein ungewöhnlicher Cluster mit drei PtII SnII-Bindungen†

Reactivity of cis-[Pd4(μ-X)4μ-C(C6F5)NMe4] (X Cl, Br, 1) towards neutral bidentate ligands

Synthesis and reactivity of phosphanido bridged 1,1′-bis(diphenylphosphino)ferrocene complexes [(RF)2Pt(μ-PPh2)2M(dppf)] [M = Pt, Pd]

Preparation of π-CS2 Complexes of Palladium Containing N- and P- Donor Ligands