Synthesis and characterization of N3Py2 ligand-based Cobalt(II), Nickel(II) and Copper(II) catalysts for efficient conversion of hydrocarbons to alcohols

Abstract

Three new complexes [Co(N3Py2)(H2O)](ClO sub(4)) sub(2) 1, [Ni(N3Py2)(H2O)](ClO sub(4)) sub(2) 2 and [Cu(N3Py2)](ClO sub(4)) sub(2) 3 (N3Py2 is N,N'-dimethyl-N-(2-(methyl(pyridin-2-ylmethyl)amino)-ethyl)-N'-(pyridin-2-ylmethyl)ethane-1,2-diamine) have been synthesized and characterized. Non-heme ligand N3Py2 have been prepared by Eschweiler-Clarke method and reported for the first time. Compounds 1 and 2 were characterized by single crystal X-ray structure analysis. The structure of 1 and 2 revealed that Co(II) cation in 1 and Ni(II) cation in 2 are bonded to the five nitrogen atoms of N3Py2 and a water molecule thus forming an octahedral motif [M(N3Py2)(H sub(2)O)] sup(2+). For compound 3, a square pyramidal geometry has been proposed based on the spectroscopic, elemental analysis and ESI-MS data. Compounds 1-3 were tested as catalysts in the oxidation of cumene and adamantane using m-CPBA. Comparative effect of counter anions on the product yields was observed when the perchlorates anions of 1-3 were replaced with tetraphenylborates to give compounds 1a-3a. The turnover numbers of alcohol over ketone product increased in order of catalysts, 1(1a) greater than 2(2a) greater than 3(3a).