DOI: 10.1002/chem.201200361 Sandwich Double-Decker LanthanideACHTUNGTRENNUNG(III) “Intracavity” Complexes Based on Clamshell-Type Phthalocyanine Ligands: Synthesis, Spectral, Electrochemical, and Spectroelectrochemical Investigations Victor E. Pushkarev,* [a, b] Alexander Yu. Tolbin, [a] Fedor E. Zhurkin, [b] Nataliya E. Borisova, [b] Stanislav A. Trashin, [a] Larisa G. Tomilova,* [a, b] and Nikolay S. Zefirov [a, b] Introduction Research in the field of rare earth element (REE) sand- wich-type phthalocyanine complexes has become increasing- ly important in recent years due to the development of effi- cient synthetic approaches [1] that can significantly extend the range of these compounds to previously inaccessible deriva- tives. The specific electronic structure, characterized by the presence of an intramolecular axial interaction between the ligand p systems, combined with extensive possibilities for functionalization [1, 2] allow sandwich complexes to find appli- cation in modern high-technology fields. [3] Structural control of their properties is possible by varying the nature of the central metal ion and substituents on the phthalocyanine rings. Thus, the distance between the phthalocyanine decks, as well as their skew angle are determined by the REE ionic radius. In turn, the electronic and steric effects of substitu- ents can influence the orbital and molecular structure of the complexes, and thus affect intrinsic physicochemical proper- ties. Herein, we report the first synthesis of double-decker phthalocyanines containing an intramolecular spacer group, which covalently binds the macrocycles at the periphery and may contribute to the appearance of structural distortions due to steric effects. Flexible-spacer clamshell-type ligand 1 ( clam,tBu Pc 2 H 4 ) was chosen as the initial substrate, which became available for research due to the previously devel- oped selective synthesis. [4] Note that ligand 1 exists as an in- separable mixture of regioisomers, which differ in the posi- tions of peripheral substituents. However, this should not significantly affect properties of the resulting compounds, since tert-butylated derivatives are known to be among the most versatile substrates in phthalocyanine chemistry. In fact, availability, excellent solubility, and comparatively weak intramolecular interactions in 1 were essential for real- ization of the synthetic goal of the present study. To our knowledge, there is a single report on a homoleptic sandwich-type REE phthalocyanine based on a flexible- spacer ligand, namely, a sandwich-clamshell-type heteronu- clear lutetiumACHTUNGTRENNUNG(III) dizinc tetraphthalocyanine, [1d] published to date, although several examples of heteroleptic com- plexes are known. [5] Thus, formation of REE sandwich Abstract: Phthalocyanine compounds of novel type based on a bridged bis- ligand, denoted “intracavity” com- plexes, have been prepared. Complexa- tion of clamshell ligand 1,1’-[benzene- 1,2-diylbis(methanediyloxy)]- bis[9(10),16(17),23(24)-tri-tert-butylph- thalocyanine] ( clam,tBu Pc 2 H 4 , 1) with lanthanideACHTUNGTRENNUNG(III) salts [LnACHTUNGTRENNUNG(acac) 3 ]·n H 2 O (Ln = Eu, Dy, Lu; acetylacetonate) led to formation of double-deckers clam,tBu Pc 2 Ln (2a–c). Formation of high molecular weight oligophthalocyanine complexes was demonstrated as well. The presence of an intramolecular co- valent bridge affecting the relative ar- rangement of macrocycles was shown to result in specific physicochemical properties. A combination of UV/Vis/ NIR and NMR spectroscopy, MALDI- TOF mass-spectrometry, cyclic voltam- metry, and spectroelectrochemistry provided unambiguous characterization of the freshly prepared bis-phthalocya- nines, and also revealed intrinsic pecu- liarities in the structure–property rela- tionship, which were supported by the- oretical calculations. Unexpected NMR activity of the paramagnetic dysprosi- um complex 2b in the neutral p-radical form was observed and examined as well. Keywords: density functional calcu- lations · electrochemistry · lantha- nides · phthalocyanines · sandwich complexes [a] Dr. V. E. Pushkarev, Dr. A. Yu. Tolbin, Dr. S. A. Trashin, Prof. L. G. Tomilova, Prof. N. S. Zefirov Institute of Physiologically Active Compounds Russian Academy of Sciences 142432 Chernogolovka, Moscow Region (Russian Federation) Fax: (+ 7) 496-524-9508 E-mail : pushkarev@org.chem.msu.ru [b] Dr. V. E. Pushkarev, F. E. Zhurkin, Dr. N. E. Borisova, Prof. L. G. Tomilova, Prof. N. S. Zefirov Department of Chemistry M. V. Lomonosov Moscow State University 119991 Moscow (Russian Federation) E-mail : tom@org.chem.msu.ru Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/chem.201200361.  2012 Wiley-VCH Verlag GmbH&Co. KGaA, Weinheim Chem. Eur. J. 2012, 18, 9046 – 9055 9046