Room Temperature Rapid Functionalization of E–H Bonds (E = O, N, S) via the Metal–Ligand Cooperation Mechanism

Cyclic Ruthenium(II)-Halocarbon Complexes Derived from Ru(II)-Induced Cyclization of Homopropargylic Halopyridines: Mechanism, Bonding and Reactivity

The activation of various homopropargylic pyridines by cis-[RuII/OsII(dppm)2Cl2] (dppm=1,1-bis(diphenylphosphino)methane) has previously been shown to generate a diverse array of metallacycles and metalated heterocyclic complexes. However, a minor structural modification of introducing a halide onto the pyridyl group of the alkyne substrate resulted in the formation of unprecedented Ru(II)/Os(II)-haloquinolizine complexes. These complexes display (1) κ2(X,C)-haloquinolizine chelates arising from the cycloisomerization of HC≡CC(OH)(CH2(6-X-2-py))(Ph) on [RuII/OsII(dppm)2]2+ moieties via a vinylidene pathway, (2) five-membered Ru/Os-X-C-N-C rings (X=F, Cl, Br) ortho- and peri-fused to quinolizinium skeletons, and (3) uncommon M-X-R bonding interactions that are atypical in coordination complexes. Despite being divalent and integrated into a five-membered Ru-X-C-N-C ring system, the X atoms in the Ru(II) complexes are susceptible to substitution by O in the presence of -OH, resulting in the formation of quinolizinium-fused ruthenaoxazole complexes. Overall, this work highlights the importance of considering metal-halocarbon bonding interactions in catalytic or coordination designs.

Stepwise construction of multi-component metal-organic frameworks

Multi-component metal-organic frameworks (MC-MOFs) are crystalline porous materials containing multiple organic ligands or mixed metals, which manifest new properties beyond the linear combination of the single component. However, the traditional one-pot synthesis method for MOFs is not always applicable for synthesizing MC-MOFs due to the competitive coordination of multiple ligands and metals. Therefore, the stepwise construction of MC-MOFs has been explored, which enables more precise control of the heterogeneity within the ordered MC-MOFs. This review provides a summary of the synthesis strategies, namely, ligand exchange, coordinative modification, covalent modification, ligand metalation, cluster metalation, and use of mixed-metal precursors, for the stepwise construction of MC-MOFs. Furthermore, we discuss the applications of MC-MOFs with ordered arrangements of multiple functionalities, focusing on gas adsorption and separation, water remediation, heterogeneous catalysis, luminescence, and chemical sensing.

Crystal structure of a dicationic PdII dimer containing a 2-[(diisopropylphosphanyl)methyl]quinoline-8-thiolate pincer ligand

A dicationic PdII dimer, bis{2-[(diisopropylphosphanyl)methyl]quinoline-8-thiolato}palladium(II) bis(hexafluoridoantimonate) dichloromethane monosolvate, [Pd2(C32H42N2P2S2)](SbF6)2·CH2Cl2, containing a 2-[(diisopropylphos-phanyl)methyl]quinoline-8-thiolate pincer ligand, was isolated and its crystal structure determined. The title compound crystallizes in the ortho-rhom-bic space group Pbca. A dimeric structure is formed by bridging coordination of the S atoms. The geometry of the butterfly-shaped Pd2S2 core is bent, with a hinge angle of 108.0 (1)° and a short Pd⋯Pd distance of 2.8425 (7) Å. These values are the lowest measured compared to ten dicationic dimers with a Pd2S2 core featuring sulfur atoms embedded in a chelating ligand. One of the two hexa-fluorido-anti-monate anions is disordered over two sets of positions with site-occupancy factors of 0.711 (5) and 0.289 (5). The crystal structure is stabilized by many C-H⋯F and C-H⋯π inter-actions, forming a supra-molecular network.

Metal-ligand-Lewis acid multi-cooperative catalysis: a step forward in the Conia-ene reaction

An original multi-cooperative catalytic approach was developed by combining metal–ligand cooperation and Lewis acid activation. The [(SCS)Pd]₂ complex featuring a non-innocent indenediide-based ligand was found to be a very efficient and versatile catalyst for the Conia-ene reaction, when associated with Mg(OTf)₂. The reaction operates at low catalytic loadings under mild conditions with HFIP as a co-solvent. It works with a variety of substrates, including those bearing internal alkynes. It displays complete 5-exo vs. 6-endo regio-selectivity. In addition, except for the highly congested ^tBu-substituent, the reaction occurs with high Z vs. E stereo-selectivity, making it synthetically useful and complementary to known catalysts.

An original multi-cooperative catalytic approach was developed by combining metal–ligand cooperation and Lewis acid activation.

A phosphomide based PNP ligand, 2,6-{Ph2PC(O)}2(C5H3N), showing PP, PNP and PNO coordination modes

Coordination chemistry of a versatile phosphomide ligand, 2,6-{Ph₂PC(O)}₂(C₅H₃N), is described.