Synthesis, structure, and spectroscopic and electrochemical properties of heteroleptic bis(phthalocyaninato) rare earth complexes with a C-4 symmetry

A series of eleven heteroleptic bis(phthalocyaninato) rare earth double-deckers [M-III(pc){pc(alpha-OC5H11)(4)}] 1-11 (M = Y, Sm-Lu; pc = phthalocyaninato; pc(alpha-OC5H11)(4) = 1,8,15,22-tetrakis(1-ethylpropoxy)phthalocyaninato) were prepared as racemic mixtures by [M-III(pc)(acac)]-induced (acac = acetylacetonato) cyclic tetramerization of 3-(1-ethylpropoxy)phthalonitrile in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) in refluxing pentanol. These compounds could also be prepared by treating [M-III(pc)(acac)] with the metal-free phthalocyanine H-2{pc(alpha-OC5H11)(4)} in refluxing octanol. The whole series of double-decker complexes 1-11 were characterized by elemental analysis and various spectroscopic methods. The molecular structures of the Sm, Eu, and Er complexes 1, 2, and 8, respectively, were also determined by single-crystal X-ray diffraction analysis. The effects of the rare earth ion size on the reaction yield, molecular structure, and spectroscopic and electrochemical properties of these complexes were systematically examined.