Oxidation of coordinated azomethine to amide. Synthetic and structural studies on a rhenium and a ruthenium system

Abstract

The title reaction is exemplified by the high yield conversions 1 -+ 2 and 3 -+ 4 by H202, and the X-ray structures of 2 and 4 are reported; the species 1+ and 3+ afford 2 and 4 respectively when treated with water.

A family of mixed ligand complexes of RuII-L [L = N-aryl-pyridine-2-aldimine], their reactions, isolation and characterization. X-ray crystal structure of [Ru(pic)(L1)2][ClO4]· CH2Cl2 [pic= 2-picolinate ion]

“…All the relevant species have been fully characterized. The reason for transformation selectivity of L is discussed on the basis of the present findings and other results [3,4] from this laboratory and elsewhere.…”

“…This must be due to stronger d~z-px interactions [13] between Ru" and x* of the imine function containing N (4), which lies trans to the strong ~-donor carboxylic acid function. Moreover, the average Ru--N (imine) length in 4 is shorter [4] by ca 0.03 ~, compared to that in trans-RuUI(L1)(L4)C12 (L4= N-phenyl-2-picolinamide). This may be attributed to the superior back-bonding in ruthenium(II) complexes.…”

Iron catalysed assembly of an asymmetric mixed-ligand triple helicate

“…The identification of water in the crystal structure of [Fe II 2 (PCP-H) 2 (PPH)]·6H 2 O·2MeCN confirms its presence in the reaction medium, and complete exclusion, perhaps in a dry-box or using an anhydrous Fe II salt, may lead to a different outcome. There is a related report of a Re and Ru-catalysed conversion of an imine to its amide, 22 but apart from our earlier paper, 2 the present example is only the second report of the direct conversion of an aroyl hydrazone to a diaroyl hydrazine.…”

Variable‐Valent Rhenium Chemistry of Conjugated Nitrogenous Ligands: Structure and Reactivity

“…The general reaction is stated in Equation (3) where the imineamide ligand in the product complex is monoanionic (Table 1). This reaction was first encountered in the case of [Re III (OPPh 3 )Cl 3 (Rpyal)] which afforded [Re IV (OPPh 3 )Cl 3 (Rpiam)] 19,25,26. The required oxidation equivalents could be provided electrochemically and/or chemically 19…”