Mixed-Metal Triple-Decker Sandwich Complexes with the PorphyrinPhthalocyaninePorphyrin Ligand System.код для вставкиСкачать
COMMUNICATIONS Mixed-Metal Triple-Decker Sandwich Complexes with the Porphyrin/Phthalocyanine/Porphyrin Ligand System** Porphyrin and porphyrin-phthalocyanine double-decker sandwich complexes [M(p),] and [M(p)(pc)] can be expanded to symmetric and asymmetric triple-decker sandwich complexes of the form [M,(P),1, [M,(P),(PC)l. and [M,(PC),(P)l (M = trivalent metal ion; p = porphyrin dianion, pc = phthaiocyanine dianion) .[I -41 The electronic structures of these tripledecker molecules have been probed by means of the electrochemical, magnetic, and spectroscopic properties of their neutral and one-electron oxidized and reduced states. UV/Vis and electrochemical studies and magnetic susceptibility measurements indicate that upon oxidation of the [(tpp)M(pc)M(tpp)] (tpp = tetraphenylporphyrin dianion) complexes in which no Ce"' center is present (M = La"', Gd"'), the phthalocyanine dianion is preferentially oxidized to the radical m o n ~ a n i o n . lIn~ ~contrast, magnetic studies and X-ray photoelectron spectroscopy show that in [(tpp)Ce(pc)Ce(tpp)], one Ce"' center is oxidized to Ce'v.[4bl We have now synthesized and characterized the following mixed-metal complexes: [(tpp)M(pc)M'(tpp)] (I(M,M')), containing no oxidizable metal (M = La, M' = Y) or one oxidizable metal (M = Ce, M = Gd, Lu, U), and [(tpp)Ce(pc)Gd(oep)] (2(Ce,Gd), oep = octaethylporphyrin dianion). The complex 2(Ce,Gd) is the first heteronuclear triple-decker sandwich complex with mixed ligands that has been analyzed by a crystal structure determination. The structural formulas of the ligands and a diagrammatic representation of the triple-decker complex is shown in Scheme 1 . Electrochemical studies of these i 1 1 tPP PC P = tPP 2(Ce, Gd), p = oep P Scheme 1. Structural formulas of the p and pc Iigands and a schematic representation of the triple-decker complexes 1 and 2 Ldboratoire de Cristdllochimie et de Chimie Structurale (UA 424) Instttut Le Bel. Universite LOUIS Pasteur 4. rue Blaise Pascal. F-67070 Strdsbours (France) Fax: Int. code +(88)415363 ['*I We thank Professor Jack FaJeT of the Department of Applied Science. Brookhaven National Laboratory, Upton. NY (USA), for valuable discussions and helpful comments and Prof. D r Roger Guilard. Universltk de Bourgogne (France). for a sample of octaethylporphyrin. This work was supported by the Centre National de la Recherche Scientifique ( U A 424). mixed-metal sandwich complexes lead to two different linear correlations of the first oxidation potentials with the mean ionic radii of the metals ([ri(M) +rj(M')]/2) that depend on the presence or absence of an oxidizable Ce"' ion. The synthesis of the heteroleptic, heteronuclear complexes l(M,M') is described in the experimental procedure. However, all attempts to grow suitable Crystals of these complexes for X-ray crystal structure analysis failed. Instead we therefore synthesized the Ce"'/Gd"' derivative with tetraphenylporphyrin, phthalocyanine, and octaethylporphyrin as ligands. This compound yielded crystals of composition 2(Ce,Gd).2 C,H,CI ,(61 which contain discrete molecules of 2(Ce,Gd) (Fig. I).''] The triple-decker molecules do not exhibit any bonding interactions with one another nor with the chlorobenzene molecules of solvation. As shown in Figure 1, both the Ce and Gd atoms are octacoordinated. The outer oep and central pc rings are rotated by an angle of 44.8(4)" relative to their eclipsed orientation. Consequently, the coordination polyhedron of the Gd atom is a slightly distorted square antiprism. In contrast, the outer tpp and central pc rings are almost eclipsed, the rotation angle being only S . O ( l ) O . Therefore, the coordination polyhedron of the Ce"' ion is a slightly distorted cube. The displacements of the metals relative to the four pyrrole-nitrogen and isoindolenitrogen mean planes of the macrocycles are as follows: Ce-tpp =1.330(4), Ce-pc =1.987(4), Gd-pc =1.775(4), and Gd-oep = 1.190(4) A. The outer tetraphenylporphyrin and octaethylporphyrin rings adopt conformations that are domed towards the Gd and Ce The phthalocyanine ring is also domed, with the result that the mean plane of its four isoindole-nitrogens lies closer to the Gd cation than the mean plane through the inner 24 atoms of the ring framework.[*' This particular conformation of the pc ring arises probably both because the ionic radius of Gd"' is smaller than that of Ce"' and because JL-TI interactions between the oep and pc are stronger than those between the tpp and pc rings. It had been previously noticed that the n-T interactions in [Zr(oep),] were stronger than those in [Zr(tpp),] .I9The UV/Vis spectra of all the complexes l(M,M') (M = La. M' = Y; M = Ce, M' = Gd, Eu, or Y) and 2(Ce,Gd) obtained in solution are very similar to each other (see Experimental Procedure) and to the spectra of triple-decker systems with two identical metals l(M.M) (M = La. Ce. Pr, Nd, Eu, Gd).[4b1 COMMUNICATIONS They are also similar to those displayed by thin films of l(Ce,Ce) obtained by sublimation under vacuum.['21These spectral properties thus confirm that the triple-decker sandwich structures, observed in the solid state for 2(Ce,Gd) and l(Ce,Ce),I4"l are retained in solution for both series of complexes I(M,M') and l(M,M). The redox behavior of the mixed-metal complexes l(M.M') was determined by cyclic voltammetry (CH,CI,, 0.1 M NBu,PF,,). The cyclic voltammograms of these species parallel those of the systems with two identical metals.[4b)All the complexes belonging to the two series l(M,M') and l(M,M) undergo three reversible oxidations and two reversible reductions. Moreover, as shown in Figure 2a and 2b, the first oxidation potentials 1(Ce. Y). yield 96 mg (70%); correct C.H,N elemental anal>sis; MS (FAB'): m / z (Yo) =I966 (100) [Mi]; UVIVis (CH,CI,) i,,,, (Ige) = 350 15.5). 415 ( 5 6). 424 (5.6).488 (5.3).558 (5.l), 607 (5.2). ](La,Y). yield 94 mg (69%); correct C , H , N elemental analysis; MS (FAB'): m/z (%) =1965 (100) [M']; UV'Vis (CH,CI,) i,,, (lgc) = 350 (5.5). 414 (5.6).424 (5.6).487 (5.3).558 (5.2).607 (5.3);' H N M R (300 MHL. CDCI3. 25 C. TMS): 6 =10.3(d.4H).9.48(m.XH),8.44(rn.8H).8 .35(t.4H).7.75(t.4H).7.71 (s.8H). 7.51 (t.4H).7.37(t.4H).7.11(t.4H).6.94(s.8H).6.84(t.4H).6.57(d.4H).630 (d. 4 H ) . 5.48 (d. 4 H ) . Received. October 16, 1995 Revised version- January 26. 1996 [Z 8476 IE] German version: A n p w . Chem 1996. 108. 942-944 Keywords: lanthanide compounds phyrinoids sandwich complexes - phthalocyanines . por- e / 1 I // 0 45 -i ,' 1L?(Ce, L L l ) 105 I 4 115 1.2 I 04-1 1 r,lA Fig 2 C orrelation between the first OXiddtion potentials €7 of the triple-decker smdwiih iomplexe\ I ( M M') and I(M M ) and the mean ionic radii of M and M o r the ionic r'ldii of M A cerium-containing complexes. cerium-free complexes (q)of the mixed-metal complexes l(M,M') examined to date also show a linear correlation with the mean ionic radii of their metal cations. However, as in the complexes containing two identical metal cations l(M,M), the slopes of the correlations depend on the presence o r absence of a Ce"' metal center. These results thus confirm that the presence o r absence of an oxidizable Ce"' metal ion controls whether the first oxidation occurs at the central atom o r the ligand.[4h.51 E.qcperinimfal Procedure I(M.M') and Z(Gd.C'e): A solution of the metal acetylacetonate [M'(acac),.nH,O] and the inetal-free poi-phyrin H i p (H,tpp or H,oep) (about 0.10 mmol) in 1.2.4trichlorobenzene was heated at reflux in a three-neck flask for four hours under argon. After cooling. ii solid sample (about 0.07mmol) of a heteroleptic sandwich complex [(tpp)M(pc)J(M = La. Ce) was added. and the resulting mixture was heated at reflux for another eight hours under argon. After cooling. a crude solid was precipitated b) addition of pentane. This solid was then extracted several times with dichloroiiieth:iiie. 'The extracts were combined. and the resulting solution was coriccntratcd under vacuum and then chromatographed on a silica gel column (3'18c m ) Elution with toluene yielded successively some porphyrin H,p and the olive green triple-decker complex [(tpp)M(pc)M'(tpp)] I(M.M') o r [(tpp)Cc(pc)(;d(oey))Z(Ce.Gd). which were precipitated by addition of pentane I(C'e. G d ) - yield 112 ing (79%). correct C.H,N elemental analysis; MS (FAB'). ni'r ( % ) = 2034 (100) [ M '1 . U V Y i s (CHZCI,) i , , [nm] , (Igi:) = 354 (5.4).418 (5 6). 4Y0 ( 5 2 ) . 55.: (5.1). 605 (5 1) Z(C'e. G d ) : yield I 1 0 ins (81'50). correct C.H.N elemental analysis: MS (FAB'): n i , z ( ' % ) = 1954(100)[;t4'1. UV~Vis(CH,CI,)i.,,,[nm](lgc) = 351 (5.4).395(5.3). 410 (5.4).465 (4.X).516(5.2).595 (4.8). Id 91 mg(04%). Correct C.H.Nelementalanalysis: MS(FAB+).n?:z ("A, I = 2052 ( l O O ) [ M '1: U V f V i s (CH2CI,) i.,,, [nm] (Igc) = 350(5.5).413 (5.6).424 (5.6). 4x9 (5.3).55X ( 5 1). 608 ( 5 2 ) . [I] a ) J. W. Buchler. B. Scharbert. 1 Am. Chem Soc 1988. llO.4272-4276;b)J. W. Buchler. H. G. Kapellmann. M. Knoff, K . L. Lay, S . Pfeifer. Z Nuturforsch. 5 1983. 38, 1339-1345: c) J. W.Buchler, P. Hammerschmitt, I. Kaufeld. J. Loffler, Chem. Ber. 1991. 124. 2151-2159.  D. Chabach, M. Tahiri. A. De Cian. J. Fischer, M. El Malouli-Bibout. R. Weiss, J. Am. Cheni. Soc. 1995. 117, 8548-8556.  a) I. W. Buchler. M. Knoff in 0,micuI Pvopwrrer und Srrui fiirp of Tetrupsrrok~s (Eds.: G . Blauer . H. Sund), De Gruyter. Berlin. 1985. pp. 91 - 105; b) J. W. Buchler, K. Elsdsser, M. Kihn-Botulinski, B. Scharbert, S.Tdnsil. ACS Svmp. Ser. 1986. 321, 94-104; c) J. W. Buchler, A. De Cian. J Fischer. M. KihnBotuhnski. H. Paulus. R. Weiss. J A m . Chem Socc 1986. /Oh'. 3652- 3659;d) J. W. Buchler, A. De Cian. J. Fischer. M. Kihn-Botulinski, R. Weiss. Inorg. Chem. 1988.27,339- 345:e) J. W Buchler. M. Kihn-Botuhnski. J. Loffler. M. Wicholas. !hid. 1989, 28, 3770-3772;f) J. W. Buchler, M Kihn-Botuhnski. J. Loffler. B Scharbert. New J. Chem. 1992, 16, 545 -553.  a) D. Chabach. M Lachkar. A. De Cian, J. Fischer. R. Weiss. New 1 Chm7. 1992. 16. 431 -433: b) D. Chabach, Doctoral Thesis. Universite Louis Pasteur de Srrasbourg. January 1994.  T. H . Tran-Thi, T. Mattioli. D. Chabach. A. De Cian, R.Weiss. 1 PI7j.s. Chenl. 1994, 34, 8279 -8288. M =  Crystal data for 2(Ce.Gd).2(C,HSCI): C,,,H,,N,,CeGd-2C,H,Cl. 2180 5. tric1inic.spacegroupPi.u =17.212(5),h =19.777(6),~=15.050(5) A. 3L = 91.10(2). p =104.46(2), = 89.6312)'. v = 4959 x A'. i)ra,cd = 1.460 Z = 2. p(CuKz)= 36.18cm-' (graphite monochromator). A total of 10922 reflections were collected at -100 C with a Philips PW 1100/16 automatic diffractometer. The resulting data set was analyzed with the EnrdfNonius SDPjVAX package. The structure was solved with the heavy atom method and refined to R ( F ) = 0.046 (Rw(F) = 0.074) using 8056 reflections with I > 3u(1).Crystallographic data (excluding structure factors) for the structure reported in this paper have been deposited with the Cambridge Crystallographic Data Centre as supplementary publication no. CCDC-179.10. Copies of the data can be obtained free of charge on application to The Director. CCDC. 12 Union Road, Cambridge CB2 1EZ. UK (fax rnt. code +(1223) 336-033;e-mail: teched(17cherncrys.cam.ac.uk) ORTEP 11: C.K. Johnson, 1976. ORNL-5138.  The separations between the mean planes through the coordinated nitrogen atoms and the mean planes through the inner 24 atoms of the framework of the oep. tpp. and pc rings are 0.208(4), 0.196(4), and 0.077(4)A. respectively.  R D. Shannon. C. T. Prewitt. Acto Cr~sru[IogrSw/. 5 1969. 25, 828-829 [lo] a ) K. Kim. W. S. Lee. H. J. Kim, S. H.Cho, G. S . Girokaml, P. A. Gorlin, K. S. Suslick, Inorg. Chem. 1991, 30, 2652-2656; b) J. W. Buchler. A. De Cian, J. Fischer. P. Hammerschmitt, R. Weiss, Chem. Eer. 1991, 124. 1051 -1058. [ I t ] 1.W. Buchler. A. De Cian. S . Elschner. J. Fischer. P. Hammerschmitt, R. Weiss, Chem. E w . 1992, 125. 107-115.  T Fournier. Docrorul Thesh, UniversitC de Paris 1X. 1994.