title: Acridine based (S,N,S) pincer ligand: designing silver(I) complexes for the efficient activation of A³ (aldehyde, alkyne and amine) coupling.
abstract: Complexes [AgL(NO3)CH3CN](1) and [AgLNO3] (2) were formed on reacting AgNO3 with L in acetonitrile for 12 h (at room temperature) and 24 h (at 90 °C), respectively, where L is a (S,N,S) pincer ligand, 4,5-bis(phenylthiomethyl)acridine, synthesized by the reaction of in situ generated PhS(-) with 4,5-bis(bromomethyl)acridine under N2 atmosphere. (1)H and (13)C{(1)H} NMR and the mass spectra of L and its two Ag-complexes were characterized. The structures of complexes 1 and 2 were established with single crystal X-ray crystallography. The Ag-S bond distances of complexes 1 and 2 are 2.5682 (11)/2.5017 (11) Å and 2.4894 (15)/2.4834 (15) Å, respectively. The ligand L in complex 2 is coordinated with the metal in a pincer mode and the complex has a pseudo-pyramidal geometry of donor atoms around the Ag. In 1, the metal is encapsulated by a ten-membered chelate ring. The two Ag(I) complexes were explored for the coupling of aldehyde, alkyne and amine (A(3) reaction) and were found to be efficient as a 2.0 mol% loading of 1 and 0.5 mol% of 2 for good conversion. Complex 2 is a rare example of a catalyst that can efficiently activate A(3) coupling at a 0.5 mol% loading of Ag.
authors.affiliation: Department of Chemistry, Indian Institute of Technology Delhi, New Delhi 110016, India. aksingh@chemistry.iitd.ac.in ajai57@hotmail.com.
authors.forename: Om
authors.initials: O
authors.lastname: Prakash
authors.forename: Hemant
authors.initials: H
authors.lastname: Joshi
authors.forename: Umesh
authors.initials: U
authors.lastname: Kumar
authors.forename: Alpesh K
authors.initials: AK
authors.lastname: Sharma
authors.forename: Ajai K
authors.initials: AK
authors.lastname: Singh
mesh_terms: D000166:Acridines / Q000737:chemistry*; D000447:Aldehydes / Q000737:chemistry; D000480:Alkynes / Q000737:chemistry; D000588:Amines / Q000737:chemistry; D056831:Coordination Complexes / Q000737:chemistry*; D018360:Crystallography, X-Ray; D008024:Ligands; D009682:Magnetic Resonance Spectroscopy; D008628:Mercury / Q000737:chemistry; D012834:Silver / Q000737:chemistry*
chemical_list: D000166:Acridines; D000447:Aldehydes; D000480:Alkynes; D000588:Amines; D056831:Coordination Complexes; D008024:Ligands; D012834:Silver; D008628:Mercury