Ferromagnetic vs antiferromagnetic coupling in bis(mu-phenoxo)dicopper(II) complexes. Tuning of the nature of exchange coupling by remote ligand substituents

Two bis(mu-phenoxo)dicopper(II) complexes, (L(CH3))(2)Cu(2)] (1) and (L(t-Bu))(2)Cu(2)] (2), where L(CH3) and L(t-Bu) represent the dianions of (methylamino)-N,N-bis(2-methylene-4,6-dimethylphenol) and of (methylamino)-N,N-bis(2-methylene-4,6-di-tert-butylphenol), respectively, are reported to demonstrate the effect of remote substituents on the nature of exchange coupling interactions between the copper(II) centers. In contrast to 1, which is as usual antiferromagnetically coupled, complex 2 is a rare example of a ferromagnetically coupled diphenoxodicopper(II) complex.