Methyloxy substituted heteroleptic bis(phthalocyaninato) yttrium complexes: Density functional calculations

The effects of alkyloxy substituents attached to one phtholocyanine ligand of three heteroleptic bis(phtholocyaninoto) yttrium complexes Y(Pc)[Pc(alpha-OCH3)(4)] (1), Y(Pc)[Pc(alpha-OCH3)(8)] (2), and Y(Pc)[Pc(beta-OCH3)(8)] (3) as well as their reduction products {Y(Pc)[Pc(alpha-OCH3)(4)]}(-) (4), {Y(Pc)[Pc(alpha-OCH3)(8)]}(-) (5), and {Y(Pc)[Pc-(beta-OCH3)(8)]}(-) (6) [H2Pc(-OCH3)(4) = 1,8,15,22-tetrakis(methyloxy)phtholocyanine; H2Pc(alpha-OCH3)(8)]}(-) = 1,4,8,11,15,18,22, 25-octakis(methyloxy)phthalocyanine; H2Pc(beta-OCH3)(8) = 2,3,9,70,16,17,23,24-octokis(methyloxy)phthalocyaninel are studied by DFT calculations. Good consistency is found between the calculated results and expen. mental data for the electronic absorption, IR, and Roman spectra of 1 and 3. Introduction of electron-donating methyloxy groups on one phthalocyanine ring of the heteroleptic doubledeckers induces structural deformation in both phtholocyanine ligands, electron transfer between the two phthalocyonine rings, changes in orbital energy and composition, shift of electronic obsorption bonds, and different vibrational modes of the unsubstituted and substituted phtholocyanine ligands in the IR and Roman spectra in comparison with the unsubstituted homoleptic counterpart Y(Pc)(2). The calculations reveal that incorporation of methyloxy substituents at the nonperipheral positions has greater influence on the structure and spectroscopic properties of bis(phthalocyaninato) yttrium double-deckers than at the peripheral positions, which increases with increasing number of substituents. Nevertheless, the substituent effect of alkyloxy substituents at one phthalocyanine ligand of the double-decker on the unsubstituted phtholocyanine ring and on the whole molecule and the importance of the position and number of alkyloxy substituents are discussed. In addition, the effect of reducing 1-3 to 4-6 on the structure and spectroscopic properties of the bis(phthalocyaninato) yttrium compounds is also discussed. This systemic DFT study is not only useful for understanding the structure and spectroscopic properties of bis(phthalocyaninato) rare earth metal complexes but also helpful in designing and preparing double-deckers with tunable structure and properties.