Double-decker complexes

After our report, many other examples of SIMs based on mononuclear lanthanide complexes have appeared. As relevant examples, we should mention the erbium-organometallic double-decker complexes [11] and the dysprosium-acetylacetonate complexes [12], and the dysprosium-DOTA (H4DOTA, 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid) complexes reported by Sessoli etal. [13]. 

Ishikawa, N., Sugita, M., Ishikawa, T., Koshihara, S.Y. and Kaizu, Y. (2003) Lanthanide double-decker complexes functioning as magnets at the single-molecular level. J. Am. Chem. Soc., 125, 8694-8695. 

Synthesis. The first double-decker complex derived from a pz ligand was reported by Ricciardi et al. (35) in 1993 (Scheme 6). The octa-octylthioporphyrazine (20) was refluxed for 1 week in the presence of Lu(OAc)3 forming the sandwich compound 21 in (an unusually high) 90% yield. 

Optical Properties. The double-decker complexes of porphyrazines have characteristic electronic absorption spectra (Table V). The intense Soret bands of the double-decker complexes are blue shifted with respect to the single pz ligand as a consequence of the strong n-n interactions. Another characteristic of sandwich compounds is the additional appearance of absorption bands shifted to the red (termed Q ) and to the blue (termed Q") of the normal g-band region. These new transitions are thought to result from orbitals delocalized over the two macrocyclic ligands (33, 82). 

A range of neutral, singly and doubly oxidized heteroleptic double-decker complexes of the type [M(IV)(P)(Pc)](n), where n = 0, +1, or +2, M=Zr or Hf, P = the dianion of octaethylporphyrin (OEP) or tetraphenylporphyrin (TPP), and Pc = the dianion of phthalocyanine, has been reported. Each oxidized or reduced compound was characterized by UV-visible and/or EPR spectroscopy. The neutral compounds all undergo two reversible ring-centered oxidations and two reversible ring-centered reductions. The redox potentials were found to depend upon the type of macrocycle. They also vary with the size of metal ion in the case of oxidation but not in reduction, where E° values are relatively unaffected and shift by only 20-40 mV upon going from Hf(P)(Pc) to Th(P)(Pc), as compared to a much larger 220-280 mV shift between E° for the first oxidation of the same compounds [27]. 

Double-decker complexes of the smaller elements (Tb-Lu) [237] are available by activated Por-precursors, namely Li2Por [238]. Lanthanide dialkylam-ides should provide an alternative route [239]. Triple-decker complexes are more readily formed compared to the Pc derivatives (Fig. 23). In an effort to force the localization of the unpaired electron on one ring, heteroleptic systems such as Por/Por and Pc/Por lanthanide sandwich complexes have been studied (Table 18 Fig. 23). 

During the last few years, adlayers of sandwich compounds such as bisPc double-decker complexes of Y, Ce, Pr, La, and Er have also been investigated at... 

Cation-induced supramolecular formation of crown ether substituted phthalocya-nines can also be regarded as due to host-guest interactions. Fig. 10 shows the proposed structure for the K+- and Ca2+-induced dimer of metallophthalocya-nines fused with four 15-crown-5 units, which serves as a typical example. The formation of these cofacial dimers has been found to go through a two-step three-stage process. The earlier works have been briefly reviewed [93, 94], Recently, Jiang et al. have prepared a series of copper(II) phthalocyanines fused with one to four 15-crown-5 unit(s) [CuPc(15-C-5) ] (n = 1 1) by heating a solution of the double-decker complexes Eu(Pc)[Pc(15-C-5) ] (n = 1-4) with Cu(OAc)2 in... 

The temperature ranges in which the magnetization relaxations are observed in [Pc2Tb] TBA+ and [Pc2Dy] TBA+, are significantly higher than any of the 3d metal-cluster SMMs. The SMM behavior was not observed for the Pc double-decker complexes with other heavy-lanthanide (Ho, Er, Tm and Yb). 

M(Pc)2 MPc[Pc(OC8H17)8] Bis(phthalocyaninato) rare earth complex Heteroleptic (phthalocyaninato) [2,3,9,10,16,17,23,24-octakis(octyloxy)-phthalocyaninato] rare earth double-decker complex... 

Fig. 5 Molecular structures of sandwich bis(phthalocyaninato) rare earth double-decker complexes used as semiconductors of p-type OFET...

Heteroleptic Bis(porphyrinato) Rare Earth Double-Decker Complexes... 

Except for the homoleptic bi(porphyrinato) and tri(porphyrinato) rare earth complexes, complexes with different porphyrin macrocycles were also investigated. To date, some sandwich type heteroleptic bis(porphyrinato) rare earth double-deckers have been synthesized. However, few have been structurally characterized via single crystal X-ray diffraction analysis [47]. Among these, Ce(IV)(OEP)(TPP) is the only structurally characterized neutral heteroleptic bis(porphyrinato) rare earth double-decker complex [48]. Using an improved short route, Coutsolelos and coworkers prepared and isolated a series of heteroleptic bis(porphyrinato)... 

Figure 4.32 The structure of complex Sm(III)H(OEP)(TPP) [48]. (Reprinted with permission from G. A. Spyroulias, etah, Synthesis, characterization, and X-ray study of a heteroleptic samarium(III) porphyrin double decker complex, Inorganic Chemistry, 34, no. 9,2476-2479, 1995. 1995 American Chemical Society.)...

Figure 4.41 The structures of (a) [Sm(III) Pc(a-OC5Hn)4 (TClPP)] and (b) [Sm(IIIH Pc(a-OC5Hii)4 (TCIPP)] [66], (Reproduced with permission from R. Wang et ah, Controlling the nature of mixed (phthalocyaninato)(porphyrinato) rare-earth(III) double-decker complexes the effects of nonperipheral alkoxy substitution of the phthalocyanine ligand, Chemistry - A European Journal, 2006, 12, 1475. Wiley-VCH Verlag GmbH Co. KgaA.)...

Polynuclear clathrochelate hydrazonates can be synthesized by the same reaction pathways as those described for oximehydrazonates (Schemes 88 and 137) using formaldehyde, triethyl orthoformate, chloral, and others as cross-linking agents. Scheme 142 represents the formation of a binuclear double-decker complex. 

Double decker complexes involving yttrium with a porphyrin and the 2,3-naphthalocyaninato (nc) group (8) have been prepared by the reaction of yttrium acac, porphyrin, and naphthalo-nitrile in the presence of l,8-diazabicyclo[5,4,0]undec-7-ene (DBU).147 148 These complexes have been studied spectroscopically and electrochemically and in the case of the Y(nc)(oep) complex the crystal structure has been determined. In Y(nc)(oep) the yttrium is eight-coordinate and sits between the two ligand planes that are separated by 2.7 A. The complex Y(nc)2 has also been prepared by the reaction of yttrium acac and naphthalonitrile in the presence of DBU.149... 

Synthetic, spectroscopic, and theoretical study of novel supramolecular structures composed of lanthanide phthalocyanine double-decker complexes 02CCR (226)93. 

Buchler, Weiss and coworkers have recently described the structures of lanthanide porphyrins. The structures of cerium(IV) doubledecker and biscerium(III) tripledecker molecules have been described [Ce(OEP)2] and [Ce2(OEP)3] have cerium ions with approximate square-antiprismatic geometry in both complexes. In the double-decker complex, the Ce-Np bond length is 2.475(1) A. The two porphyrin rings are rotated by about 43° with respect to each other. A quite similar structure is seen for [Eu(OEP)2] . In this structure, Eu-Np is slightly longer at 2.510(2) A. The two rings... 

Scandium vapour will react with the phosphyne P=C Bu to produce a triple-decker sandwich complex with the 1,3,5 triphosphinine ring, together with a double-decker complex with tive-membered rings [10]. Various other complexes can be obtained with different metal vapours. 

A double-decker complex of bis-phthalocyanines of lanthanides is aniuterestiug model of H-aggregates of phthalocyanines. Therefore, it is important to study their properties. 

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