Studies of "Pinwheel-Like" Bis[1,8,15,22-tetrakis(3-pentyloxy)phthalocyaninato] Rare Earth(III) Double-Decker Complexes

Homoleptic bis(phthalocyaninato) rare‐earth double‐deckers complexes [MIII{Pc(α‐OC5H11)4}2] (M=Eu, Y, Lu; Pc(α‐OC5H11)4=1,8,15,22‐tetrakis(3‐pentyloxy)phthalocyaninate) have been prepared by treating the metal‐free phthalocyanine H2Pc(α‐OC5H11)4 with the corresponding M(acac)3⋅nH2O (acac=acetylacetonate) in refluxing n‐octanol. Due to the C4h symmetry of the Pc(α‐OC5H11)4 ligand and the double‐decker structure, all the reactions give a mixture of two stereoisomers with C4h and D4 symmetry. The former isomer, which is a major product, can be partially separated by recrystallization due to its higher crystallinity. The molecular structure of the major isomer of the Y analogue has been determined by single‐crystal X‐ray diffraction analysis. The metal center is eight‐coordinate bound to the isoindole nitrogen atoms of the two phthalocyaninato ligands, forming a distorted square antiprism. Such an arrangement leads to an interesting “pinwheel” structure when viewed along the C4 axis, which assumes a very unusual S8 symmetry. The major isomers of all these double‐deckers have also been characterized with a wide range of spectroscopic methods. A systematic investigation of their electronic absorption and electrochemical data reveals that the π–π interaction between the two Pc(α‐OC5H11)4 rings is weaker than that for the corresponding unsubstituted or β‐substituted bis(phthalocyaninato) analogues. Pinwheels: Homoleptic bis[1,8,15,22‐tetrakis(3‐pentyloxy)phthalocyaninato] rare‐earth double‐deckers [MIII{Pc(α‐OC5H11)4}2] (M=Eu, Y, Lu), which have a “pinwheel‐like” molecular structure with C4h symmetry (shown here), have been prepared by treating the metal‐free phthalocyanine H2Pc(α‐OC5H11)4 with the corresponding M(acac)3⋅nH2O in refluxing n‐octanol.