Dinuclear Manganese(II), Cobalt(II), and Nickel(II) Aryl Phosphates Incorporating 4′‐Chloro‐2,2′:6′,2′′‐Terpyridine Coligands – Efficient Catalysts for Alcohol Oxidation

Abstract

The dinuclear cyclo(metallo)phosphates [M(dipp)-(Cl-terpy)] 2 [M = Mn (1), Ni (2)] and the mononuclear cobalt phosphate [Co(dippH)(Cl-terpy)(MeOH)(H 2 O)]·dippH (3) were synthesized through the reactions of 4′-chloro-2,2′:6′,2′′-terpyridine (Cl-terpy) and 2,6-diisopropylphenyl phosphate (dippH 2 ) with manganese, nickel, and cobalt acetates. The formation of 1-3 is supported by spectroscopic, thermogravimetric, and microanalytical data. The molecular structures of 1 and 3 were confirmed by single-crystal X-ray diffraction studies. Compounds 1 and 2 are dimeric and feature two octahedral metal [a]

Metal‐Terpyridine Complexes in Catalytic Application – A Spotlight on the Last Decade

“…In order to develop catalysts for the oxidation of alcohols, Murugavel and co‐workers prepared a series of dinuclear complexes in which the M(II)‐tpy units were bridged by organophosphates (M=Mn, Co, Ni) . From these, the Mn(II)‐containing system was found to catalyze the oxidation of primary and secondary alcohols with TBHP as oxidant (see Section 2.5.1); the Co(II) and Ni(II) counterparts were less efficient in terms of substrate conversion and selectivity.…”

“…As pointed above (Section 2.3.2), the dinuclear organophosphate‐bridged Mn(II)‐tpy complex 12 (Figure ) was used as catalyst for the oxidation of alcohols with t BuOOH, as oxidant . A range of alcohols was screened to identify the scope of the optimized oxidation protocol (Table ).…”

“… Schematic representation and solid‐state structure of the dinuclear Mn(II) complex 12 . Figure reproduced with kind permission; © 2018 Wiley‐VCH.…”

Polydentate 4‐Pyridyl‐terpyridine Containing Discrete Cobalt Phosphonate and Polymeric Cobalt Phosphate as Catalysts for Alcohol Oxidation

“…Co‐ligands such as bipyridine, phenanthroline and Cl‐tpy have also been employed to control their nuclearity. [13b], [13c], Cobalt phosphates find potential applications as single source precursors for fine particle ceramics, for CO 2 adsorption, as molecular magnets, and as catalysts for water oxidation reactions. [12c], [13d], Although transition metal complexes of tpy, pytpy and their derivatives have been implicated recently to have great potential as catalysts in organic transformation reactions such as asymmetric cyclopropanation of styrenes, alkene hydroboration, etc., they have rarely been employed as alcohol oxidation catalysts.…”

“…In a series of recent investigations, we have employed a number of transition metal catalysts for selective and efficient oxidation of alcohols. The catalytic systems that have been studied include, silica supported Schiff base complexes, dinuclear Mn II , Co II Ni II arylphosphates incorporating 4′‐chloro‐2,2′:6′,2′′‐terpyridine (Cl‐tpy) ancillary ligand, bulky 2,6‐dibenzhydryl‐4‐methylaniline derived Schiff base complexes of Pd II , Cu II , and Co II , and arylimido hexamolybdates . Continuing on our earlier efforts, in this article we wish to report new cobalt terpyridine complexes containing lipophilic phosphate/phosphonate ligands as homogeneous catalysts for alcohol oxidation reactions.…”