Challenges in Catalytic Hydrophosphination

Despite significant advances, metal-catalyzed hydrophosphination has ample room for discovery, growth, and development. Many of the key successes in metal-catalyzed hydrophosphination over the last decade have indicated what is needed and what is yet to come. Reactivity that is absent from the literature also speaks to the challenges in catalytic hydrophosphination. This Concept article discusses and highlights recent developments that address the ongoing challenges, and identifies areas in metal-catalyzed hydrophosphination that are underdeveloped. Advances in product selectivity, catalyst design, and both unsaturated and phosphine substrates illustrate the ongoing development of the field. Like all catalytic transformations, the benefits are realized through catalyst, ligand, and conditions, and consideration of those features are the route to a yet more efficient and broadly applicable reaction

Insertion of Benzylisocyanide into a Zr-P bond and Rearrangement. Atom-Economical Synthesis of a Phosphaalkene

Reaction of (N3N)ZrPHPh (1, N3N = N(CH2CH2NSiMe3)33−) with PhCH2NC affords the 1,1-insertion product (N3N)Zr[C(PHPh)NCH2Ph] (2), which thermally rearranges to the phosphaalkene-containing complex, (N3N)Zr[N(CH2Ph)C(H)PPh] (3)

Bis(4-methyl-N-{(2Z,4E)-4-[(4-methyl­phen­yl)imino]­pent-2-en-2-yl}anilinido)zinc

The title compound, [Zn(C19H21N2)2], appears to be the first example of a zinc complex supported by two β-diketiminate (nacnac) ligands. This complex crystallizes with a distorted tetra­hedrally coordinated ZnII atom that diposes the two nacnac ligands approximately orthogonally to one another [angle between the two N—Zn—N mean planes is 89.91 (10)°], with average Zn—N bond lengths of 1.992 (4) Å

Spin Exchange Interaction in Substituted Copper Phthalocyanine Crystalline Thin Films

All rights reserved. The origins of spin exchange in crystalline thin films of Copper Octabutoxy Phthalocyanine (Cu-OBPc) are investigated using Magnetic Circular Dichroism (MCD) spectroscopy. These studies are made possible by a solution deposition technique which produces highly ordered films with macroscopic grain sizes suitable for optical studies. For temperatures lower than 2K, the contribution of a specific state in the valence band manifold originating from the hybridized lone pair in nitrogen orbitals of the Phthalocyanine ring, bears the Brillouin-like signature of an exchange interaction with the localized d-shell Cu spins. A comprehensive MCD spectral analysis coupled with a molecular field model of a σπ-d exchange analogous to sp-d interactions in Diluted Magnetic Semiconductors (DMS) renders an enhanced Zeeman splitting and a modified g-factor of -4 for the electrons that mediate the interaction. These studies define an experimental tool for identifying electronic states involved in spin-dependent exchange interactions in organic materials

Anodic oxidation of ethynylferrocene derivatives in homogeneous solution and following anodic deposition onto glassy carbon electrodes

Eight ferrocene derivatives linked by either an ether, amine, or phenylacetylene moiety to a terminal ethynyl group were covalently deposited on glassy carbon electrodes by anodic electrochemical methods. The lithio activation method, in which the terminal hydrogen of the ethynyl group is replaced by a lithium atom before anodic oxidation, was successfully employed in all cases. Direct oxidation of the unactivated ethynyl group also resulted in surface deposition. Surface coverages between 1 x 10 ‐10 mol cm ‐2 and 14 x 10 ‐10 mol cm ‐2 were achieved. Cyclic voltammetry scans of the modified electrodes in pure electrolytes differed depending on the size of the supporting electrolyte anion, as little as half the current being measured for a [B(C 6 F 5 ) 4 ] ‐ vs. [PF 6 ] ‐ solution, suggesting differences in ion transport near the electrode surface. An ether‐linked ethynylferrocenium ion ( 5 + ) was isolated after electrolytic and chemical oxidation of 5 and characterized by X‐Ray crystallography as its [SbCl 6 ] ‐ salt

Zirconium-catalyzed alkene hydrophosphination and dehydrocoupling with an air-stable, fluorescent primary phosphine

Zirconium-catalyzed alkene hydrophosphination and dehydrocoupling with an air-stable, fluorescent primary phosphine 8-[(4-phosphino)phenyl]-4,4-dimethyl-1,3,5,7-tetramethyl-2,6-diethyl- 4-bora-3a,4a-diaza-s-indacene furnishes fluorescent phosphine products. Hydrophosphination of the fluorescent phosphine produces products with a complete selectivity for the secondary product. A key intermediate in catalysis, a zirconium phosphido compound, was isolated

Group-Transfer Reactions of Nickel-Carbene and -Nitrene Complexes with Organoazides and Nitrous Oxide that Form New C=N, C=O, and N=N Bonds

This article discusses group-transfer reactions of nickel-carbene and -nitrene complexes with organoazides and nitrous oxide that form new C=N, C=O, and N=N bonds

Triamidoamine-supported zirconium: Hydrogen activation, Lewis acidity, and: Rac -lactide polymerization

Investigation of a triamidoamine-supported zirconium hydride intermediate, important to a range of catalytic reactions, revealed the potential Lewis acidity of [κ5-N,N,N,N,C-(Me3SiNCH2CH2)2NCH2CH2NSiMe2CH2]Zr (1). A preliminary study of 1 as a precursor for the polymerization of rac-lactide showed modest activity but indicated that five-coordinate zirconium complexes with tetra-N donor ligands may be an avenue for further development in group 4 metal lactide polymerization catalysis

Structural versatility of the quasi-aromatic Möbius type zinc(II)-pseudohalide complexes : experimental and theoretical investigations

In this contribution we report for the first time fabrication, isolation, structural and theoretical characterization of the quasi-aromatic Mobius complexes [Zn(NCS)(2)L-I] (1), [Zn-2(mu(1,1)-N-3)(2)(L-I)(2)][ZnCl3(MeOH)](2)center dot 6MeOH (2) and [Zn(NCS)L-II](2)[Zn(NCS)(4)]center dot MeOH (3), constructed from 1,2-diphenyl-1,2-bis((phenyl(pyridin-2-yl)methylene)hydrazono)ethane (L-I) or benzilbis(acetylpyridin-2-yl)methylidenehydrazone (L-II), respectively, and ZnCl2 mixed with NH4NCS or NaN3. Structures 1-3 are dictated by both the bulkiness of the organic ligand and the nature of the inorganic counter ion. As evidenced from single crystal X-ray diffraction data species 1 has a neutral discrete heteroleptic mononuclear structure, whereas, complexes 2 and 3 exhibit a salt-like structure. Each structure contains a Zn-II atom chelated by one tetradentate twisted ligand L-I creating the unusual Mobius type topology. Theoretical investigations based on the EDDB method allowed us to determine that it constitutes the quasi-aromatic Mobius motif where a metal only induces the pi-delocalization solely within the ligand part: 2.44|e| in 3, 3.14|e| in 2 and 3.44|e| in 1. It is found, that the degree of quasi-aromatic pi-delocalization in the case of zinc species is significantly weaker (by similar to 50%) than the corresponding estimations for cadmium systems - it is associated with the Zn-N bonds being more polar than the related Cd-N connections. The ETS-NOCV showed, that the monomers in 1 are bonded primarily through London dispersion forces, whereas long-range electrostatic stabilization is crucial in 2 and 3. A number of non-covalent interactions are additionally identified in the lattices of 1-3