Cyclometalated complexes derived from calix[4] arene bisphosphites and their catalytic applications in cross-coupling reactions

Maji, Pathik and Mahalakshmi, Lepakshaiah and Krishnamurthy, Setharampattu S and Nethaji, Munirathinam (2011) Cyclometalated complexes derived from calix[4] arene bisphosphites and their catalytic applications in cross-coupling reactions. In: Journal of Organometallic Chemistry, 696 (20). pp. 3169-3179.

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Abstract

Palladium and platinum dichloride complexes of a series of symmetrically and unsymmetrically substituted 25,26;27,28-dibridged p-tert-butyl-calix[4]arene bisphosphites in which two proximal phenolic oxygen atoms of p-tert-butyl-or p-H-calix[4]arene are connected to a P(OR) ( R = substituted phenyl) moiety have been synthesized. The palladium dichloride complexes of calix[4]arene bisphosphites bearing sterically bulky aryl substituents undergo cyclometalation by C-C or C-H bond scission. An example of cycloplatinated complex is also reported. The complexes have been characterized by NMR spectroscopic and single crystal X-ray diffraction studies. During crystallization of the palladium dichloride complex of a symmetrically substituted calix[4]arene bisphosphite in dichloromethane, insertion of oxygen occurs into the Pd-P bond to give a P,O-coordinated palladium dichloride complex. The calix[4]arene framework in these bisphosphites and their metal complexes adopt distorted cone conformation; the cone conformation is more flattened in the metal complexes than in the free calix[4]arene bisphosphites. Some of these cyclometalated complexes proved to be active catalysts for Heck and Suzuki C-C cross-coupling reactions but, on an average, the yields are only modest. (C) 2011 Elsevier B.V. All rights reserved.

Item Type:	Journal Article
Publication:	Journal of Organometallic Chemistry
Publisher:	Elsevier Science
Additional Information:	Copyright of this article belongs to Elsevier Science.
Keywords:	Calix[4]arene bisphosphites;Palladium and platinum dichloride complexes;Cyclometalation;Heck and Suzuki coupling reactions
Department/Centre:	Division of Chemical Sciences > Inorganic & Physical Chemistry
Date Deposited:	08 Sep 2011 11:32
Last Modified:	08 Sep 2011 11:32
URI:	http://eprints.iisc.ac.in/id/eprint/40396

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