The catalytic activity of Ru(II)-arene complexes containing ferrocene thiosemicarbazone (Fc-TSC) ligands was investigated towards the selective synthesis of 1,2-disubstituted benzimidazoles via acceptorless dehydrogenative coupling of diamines with primary alcohols. A series of Ru(II)-p-cymene complexes (1-4) containing Fc-TSC ligands (L 1 -L 4 ) were synthesized and characterized. From single crystal X-ray crystallographic studies, the molecular structures of L 3 and 4 were confirmed. The influence of electronic effect of ligands on the catalytic activity of their complexes was studied. The activity of good performer i. e. 4 was compared with that of its benzene counterpart (5). The catalysis was extended to aromatic, aliphatic and heterocyclic substituted primary alcohols, and phenylenediamines with electron-donating or -withdrawing substituents. Overall, synthesis of 1,2-disubstituted benzimidazoles was accomplished with good to moderate yields, with hydrogen and water as only by-products.
Tetranuclear
organopalladium(II) complexes 1–3 and mononuclear complex 4 have been synthesized by
the complexation of 3-acetyl-7-methoxy-2H-chromen-2-one
derived Schiff bases with potassium tetrachloropalladate K2[PdCl4]. Structural confirmation for the complexes (1–3) has been achieved by single-crystal
X-ray diffraction analysis. The ligands are found to bind with the
palladium ion through its azomethine nitrogen, thiolate sulfur, and
C4 carbon atom of the coumarin moiety subsequent to C–H activation.
The monomeric nature of complex 4 was confirmed from
its mass spectroscopic data. In complex 4, coordination
occurred via the lactone oxygen, azomethine nitrogen, and thiolate
sulfur atoms. Computational study has been used to determine the optimized
molecular structures of the complexes. An explanation on the energies
of their highest occupied and lowest unoccupied molecular orbital
levels and their electronic spectra has also been provided on the
basis of the theoretical calculations. A systematic study of the application
of these complexes as catalysts in Suzuki–Miyaura coupling
(SMC) has been done with different aryl halides and phenyl boronic
acid in an aqueous medium. Optimization of the reaction indicated
that complex 2 exhibits greater efficiency than other
complexes. An appreciable yield of the coupled products was observed
with the minimum use of catalyst (μmol), and the C–C
coupling has been confirmed by GC/GC-MS. An interesting result of
our catalyst is the coupling of four different chloroquinolines with
phenyl boronic acid to afford the coupled products in good yields.
Fe and Cr based MOFs (MIL-88B) act as efficient and reusable catalysts for transfer hydrogenation of carbonyl compounds including bio-derived substrates.
Three copper(I) complexes, [CuCl(L)(PPh 3 ) 2 ] [L = FL (1), BL (2) or TL (3)] were prepared from [(PPh 3 ) 2 Cu-(μ-Cl) 2 Cu(PPh 3 )] and N-carbamothioylfuran-2-carboxamide (FL), N-carbamothioylbenzamide (BL) or N-carbamothioylthiophene-2-carboxamide (TL) ligands in benzene and four-coordinated tetrahedral copper complexes were well characterized by various spectroscopic techniques (UV/Vis, FT-IR, 1 H NMR, 13 C NMR and 31 P NMR). The molecular structure of the ligands (FL and BL) and complexes was established from single-crystal X-ray diffraction studies. Copper complexes have been shown to cata- [a]
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