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Organophosphorus compounds possessing a P–P double-bond character are intriguing materials in coordination chemistry because it is possible to form a variety of coordination modes from the π-bond in addition to the lone pairs. We report herein the complexation of a new bidentate ligand, ethylene-tethered bis(binaphthyldiphosphene) (S,S)-2, with palladium(II) species. The reaction of (S,S)-2 with [Pd(π-allyl)(cod)](SbF6) and PdCl2(cod) afforded η1/η1-bis(diphosphene) complex 7 and η1-diphosphene/η2-phosphanylphosphide complex 8, respectively. The latter was characterized by a chloride migration from the palladium atom to a phosphorus atom due to the high electron-accepting character of the P＝P moiety. Theoretical calculations revealed the migration process and nature of complex 8. [ABSTRACT FROM AUTHOR]

Chromium-complexed arenes with a diphenylphosphine substituent on the ring and dimethylamine or methoxyl substituent at the benzylic position complexed with palladium are effective catalysts in aryl amination reactions involving aryl bromides to generate cyclic and acyclic secodary amines. The steric and electronic factors involved in using these palladium catalysts are significant contributors to the efficient catalysis of the amination reaction.

The synthesis and characterization of mono Cr(CO3) complexes of biphenyl compounds are presented. The scheme involves the reaction of tricarbonyl(2,6-disubstituted 1-bromobenzene)chromium complexes with ortho-substituted arylboronic acids. Analysis showed that the axial stereochemical behavior of the products is influenced by the steric effects of the ortho substituents of the arene(chromium) complexes and phenylboronic acids.

A reaction between [Cp*FeCl][.sub.x] and LiNHPh (1equiv to Fe) produces a new paramagnetic Fe(II)-Fe(III) [mu.sub.2]-amido--[mu.sub.2]-imido complex [(Cp*Fe)[.sub.2]{[mu.sub.2]-NHPh}{[mu.sub.2]-NPh)]. This complex, upon interaction with 2,2'-azobis(2,4-dimethylvaleronitrile), undergoes a net N-H hydrogen atom abstraction reaction to give a dimagnetic Fe(III)-Fe(III) [mu.sub.2]-imido dimer [Cp*Fe{[mu.sub.2]-Nph}][.sub.2], and their molecular structures are determined by single-crystal X-ray diffraction.

The gold(I)‐catalyzed intramolecular hydroarylation of o‐ethynylarylphosphonium salt 1 gave phosphepinium 2 or phosphinium salt 3. The use of methylphosphonium salt instead of phosphine chalcogenide is key to success for the intramolecular hydroarylation. The substrate with 2‐methoxyphenyl group at the alkyne position preferentially provided seven‐membered phosphacycle 2, while that with a hydrogen did six‐membered phosphacycle 3. Theoretical calculations revealed that the activation energy of 6‐exo‐dig cyclization in the substrate with the aryl group increased due to the steric repulsion of the two aryl rings. Furthermore, the Wittig‐type reaction of phosphepinium salt 2 a afforded methyl‐substituted phosphepin oxide 4 a via the elimination of an aryl group. [ABSTRACT FROM AUTHOR]

The amido complexes have provided a chemistry that is attributed to a reactive imido species [Cp*Rh([[mu].sub.2]-NPh)RhCp*] including a formal [2+2] cycloaddition reaction with unactivated alkynes. A sterically hindered arylimido ligand is used for isolating and characterizing the relevant coordinatively unsaturated imidodirhodium complex.

A palladium-catalyzed double C-H arylation reaction for the synthesis of helicenes from Z,Z-bis(bromostilbene)s is reported.

The stereoselective nucleophilic aromatic substitution reactions of the various planar chiral chromium complexes are widely used for the synthesis of two enantiomers of the N-aryl indoles, containing several chiral N-C bonds. The results show that the stereochemistry of the products completely depends on the position of the substituent in the indole, though an identical planar chiral arene chromium complex can be used for the production of both the enantiomers.

Axially chiral biaryls are important as chiral ligands or auxiliaries in asymmetric reaction, and for biologically active natural products. Nucleophilic displacement of an ortho-methoxy group of chiral aryl oxazolines by aryl grignard reagents are widely employed in asymmetric biaryl syntheses.

Recently, planar‐chiral phosphine‐olefin ligands based on (η6‐arene)chromium(0) and (η5‐cyclopentadienyl)manganese(I), which are known as first‐ and second‐generation, respectively, have been developed. These ligands were employed for Rh‐catalyzed asymmetric 1,4‐addition to enones. First‐generation ligands involve high enantioselectivity for cyclic enones (>98% ee). Second‐generation ligands involve high enantioselectivity for not only cyclic enones but also for acyclic enones (>98% ee). In this study, we have performed DFT calculations to investigate the origin of enantioselectivity. The theoretical values of enantioselectivities were found to be in good agreement with the experimental values obtained for a cyclic enone, 2‐cyclopenten‐1‐one, using both the first‐ and second‐generation ligands. Regarding an acyclic enone, 3‐penten‐2‐one, it was found that the s‐cis type decreases the enantioselectivity because the transition states in the s‐cis type have a large steric repulsion. Energy decomposition analysis (EDA) and natural bond orbital (NBO) analysis indicate that it is important to study the orbital interactions in the transition states of the insertion step for the acyclic enone attacked from si‐face with the second‐generation ligand. © 2018 Wiley Periodicals, Inc. Planar‐chiral phosphine‐olefin ligands based on (η6‐arene)chromium(0) called "first‐generation" and (η5‐cyclopentadienyl)manganese(I) called "second‐generation" were developed. These ligands are employed for Rh‐Catalyzed asymmetric 1,4‐addition to enones. Second‐generation ligands give high enantioselectivity for an acyclic enone. Energy decomposition analysis and natural bond orbital analysis indicate that orbital interactions in the transition states with the second‐generation ligand attacked from the si‐face are important. [ABSTRACT FROM AUTHOR]