Substituted phenols as ligands. Part II. Copper(II) complexes

Abstract

Copper(II) complexes with the 2-methoxyphenolate ion, its 4-formyl-, 4-nitro-, and 4-formyl-6-methoxy-derivatives and the 2-ethoxy-4-formylphenolate ion are reported. Hydrated compounds with the formula Cu(ligand)₂,-xH₂O (where x= 2, 3, or 4) are generally obtained from aqueous solution which on dehydration yield the complexes Cu(ligand)₂. The complexes possess a distorted octahedral stereochemistry with the exception of bis-(2-methoxyphenolato)copper(II), which has no hydrate, which may be a rare case of the CuO₄ distorted tetrahedral chromophore. One isomeric form of bis(2-ethoxy-4-formylphenolato)copper(II) dihydrate may have a quasi-tetrahedral stereochemistry but could be six-co-ordinate with a rhombic perturbation. Bis(2-ethoxy-4-formylphenolato)copper(II) dihydrate has a tetragonal six-co-ordinate isomer. Both forms dehydrate to give six-co-ordinate products which are identical.

Two types of magnetic behaviour are observed. The anhydrous complexes have subnormal room temperature moments arising from magnetic exchange. Two of them display Néel points and these results correspond to the expected behaviour for interacting dimeric aggregates. The others fit the lsing one-dimensional magnetic model in which the crystal consists of a number of infinite chains of interacting magnetic centres. The hydrates have normal magnetic moments suggesting magnetically isolated copper(II) ions.

There is no conclusive evidence regarding the participation of the 2-alkoxy-group in co-ordination, however, complexes with no 2-substituent could not be prepared.