Formation of heterobinuclear µ-nitrido complexes with a Mn-N-Fe moiety by reaction of nitrido(octaphenyltetraazaporphyrinato)manganese(V) with iron(III) porphyrins

摘要

Mendeleev Communications Electronic Version, Issue 5, 1997 (pp. 169–212) Formation of heterobinuclear -nitrido complexes with a Mn–N–Fe moiety by reaction of nitrido(octaphenyltetraazaporphyrinato)manganese(V) with iron(III) porphyrins Pavel A. Stuzhin,*a Mahmud Hamdusha and Heiner Homborgb a Department of Organic Chemistry, State Academy of Chemical Technology, 153460 Ivanovo, Russian Federation.Fax: +7 0932 37 7743; e-mail: stuzhin@icti.ivanovo.su b Instutut für Anorganische Chemie, Christian-Albrechts-Universität zu Kiel, D-24098 Kiel, Germany Nitrido(octaphenyltetraazaporphyrinato)manganese(V) (NºMnOPTAP) obtained by treatment of chlorine on acido(octaphenyltetraazaporphyrinato) manganese(III) (X)MnOPTAP; X = Cl, AcO, HSO4 in chloroform solution saturated with ammonia, reacts with acido(octaphenyltetraazaporphyrinato)iron(III) (X)FeOPTAP; X = Cl, Br, AcO forming the heterometallic m-nitrido complex m-(MnNFe)(OPTAP)2; m-nitrido complexes with a dissimilar porphyrin ligand on each metal have also been prepared.Binuclear m-nitrido iron complexes of porphyrins,1 tetraazaporphyrins2 and phthalocyanine3,4 can be easily obtained by thermolysis of the corresponding azidoiron(III) complexes.Heating of azido(tetraphenylporphyrinato)iron(III) (N3)FeTPP in the presence of iron or ruthenium phthalocyanines (FePc, RuPc) results in the formation of mixed binuclear m-nitrido complexes (TPP)Fe(m-N)Fe(Pc) and (TPP)Fe(m-N)Ru(Pc).5 It was supposed1,6 that nitrido(tetraphenylporphyrinato)iron(V) (NºFeTPP) is a reactive intermediate in the formation of m-N(FeTPP)2 from (N3)FeTPP.However, due to the extremely high instability of the nitridoiron(V) complexes NºFeTPP was detected7 as a photolysis product of (N3)FeTPP only below 150 K their role in m-nitrido complex formation has not received any direct confirmation as yet. Unlike nitridoiron(V) complexes nitridomanganese(V) complexes of porphyrins8 and phthalocyanines9 are very stable.In order to throw some light on the mechanism of the m-nitrido complex formation, we have obtained stable nitrido(octaphenyltetraazaporphyrinato)- manganese(V) (NºMnOPTAP 3; Scheme 1) and attempted to use it in the synthesis of the heterometallic m-nitrido complexes (Scheme 2). Melting of (E)-1,2-diphenyl-1,2-dicyanoethylene 1 with anhydrous manganese(II) acetate in a 1:1 molar ratio at 270 °C gave acetato(octaphenyltetraazaporphyrinato)manganese(III) (AcO)MnOPTAP 2; yield 85.† NºMnOPTAP 3 was obtained by bubbling chlorine through a cooled (–20 °C) solution of 2 in chloroform saturated with gaseous ammonia (yield 61).‡ Other acidomanganese(III) complexes (X)MnOPTAP (e.g.X = Cl, HSO4) can also be used as a starting material.Complex 2 can bind ammonia as an axial ligand forming hexacoordinated ammine complexes of manganese(III), (AcO)(H3N)MnOPTAP, or on more prolonged exposition of manganese(II), (H3N)2MnOPTAP. Coordination of ammonia to 2 and subsequent conversion of the ammine complexes to NºMnOPTAP under action of chlorine can be followed by UV/VIS spectroscopy (Figure 1). Whereas the spectrum of (AcO)(H3N)MnOPTAP is almost identical with that of 2 Figure 1(a), additional characteristic bands appear at 830 and 886 nm for (H3N)2MnOPTAP Figure 1(b).These ammine complexes can be chlorinated to give, we suppose, unstable intermediate complexes containing N,N-dichloro- † Spectral data for 2: Found (): C, 76.28; H, 4.54; N, 10.49. Calc. for C66H43N8O2Mn (): C, 76.59; H, 4.19; N, 10.83.UV/VIS CHCl3, lmax/nm (log e): 285 (4.66), 331sh, 414 (4.56), 475 (4.39), 613sh, 665 (4.60). Camenzind and Hill11 have reported the preparation of octaphenyltetraazaporphyrinatomanganese(II) from 1 and manganese powder with low yield (5.7); no spectral data have been reported for this compound. ‡ Spectral data for 3: Found (): C, 77.76; H, 4.18; N, 12.55.Calc. for C64H40N9Mn (): C, 77.65; H, 4.07; N, 12.73. FD-MS m/z: NºMnOPTAP+ (990.4, 12); MnOPTAP+ (975.3, 100). UV/VIS CHCl3, lmax/nm (log e): 270sh, 345sh, 361 (4.65), 447 (4.22), 577 (4.12), 601sh, 629 (4.91). amidomanganese(III), (Cl2N)MnOPTAP, or N-chloronitrenomanganese( IV), ClN=MnOPTAP, which easily split off chlorine forming stable nitridomanganese(V) complex 3 Figure 1(c).In the absence of ammonia complex 2 is oxidized irreversibly with chlorine producing colourless products. A substantial hypsochromical shift of the p®p* transitions of the macrocycle observed for 3 as compared with 2 is in agreement with strengthening of the p-donation effect expected for d2 complexes such as NºMnOPTAP. The structure of 3 is confirmed by the presence in the mass spectrum of a molecular ion peak of NºMnOPTAP+ at m/z = 990.4 and by the appearance of the MnºN stretching vibration as a weak band at 1054 cm–1 in the IR spectrum and as a medium-strong line at 1058 cm–1 in the resonance Raman spectrum.The heterometallic m-nitrido complex 5, m-(MnNFe)- (OPTAP)2, was obtained by reaction of the nitridomanganese(V) complex 3 with chloroiron(III) complex 4, (Cl)FeOPTAP,10 in a boiling benzene solution (3:4 = 1:1.5 molar ratio) (Scheme 2).The m-nitrido complex 5 was chromatographically purified and separated from an admixture of m-oxodimer O(FeOPTAP)2, formed partially from 4 (neutral Al2O3, eluent CHCl3, yield of 5 23).§ The Mn/Fe ratio determined by a flame photometry § Spectral data for 5: Found (): C, 77.84; H, 3.95; N, 12.03; Mn, 2.72; Fe, 2.6.Calc. for C128H80N17MnFe (): C, 78,16; H, 4.10; N, 12.11; Mn, 2.79; Fe, 2.84. FD-MS m/z: NºMnOPTAP+ (990.4, 2.9), FeOPTAP+ (976.3, 89), MnOPTAP+ (975.3, 100). UV/VIS CHCl3, lmax/nm (log e): 345 (4.81), 437sh, 583 (4.55), 642 (4.66). m N N N N N N N N Mn Ph Ph Ph Ph Ph Ph Ph Ph OAc C Ph C Ph N N N N N N N N N N Mn Ph Ph Ph Ph Ph Ph Ph Ph N Mn(OAc)2 270 °C NH3 then Cl2 –20 °C 1 2 2 3 (AcO)MnOPTAP NºMnOPTAP Scheme 1Mendeleev Communications Electronic Version, Issue 5, 1997 (pp. 169–212) method and the CHN elemental analysis data for 5 are in reasonable agreement with the proposed formula, m-(MnNFe)- (OPTAP)2. The mass spectrum of 5 obtained by a field desorption method contains mass peaks (in m/z) corresponding to the monomer constituents of the mixed m-nitrido complex (NºMnOPTAP+ 990.4; MnOPTAP+ 975.3; FeOPTAP+ 976.3), but no molecular ion peak expected for C128H80N17MnFe at m/z = 1965.6 has been detected.Formation of 5 can be easily monitored by UV/VIS spectroscopy: characteristic absorption bands of the initial complexes 3 (629 nm) and 4 (710 nm) disappear and a broad doublet (642, 583 nm) appears.Such splitting of the Q-band, being a result of excitonic interactions of the adjacent p-systems, is characteristic of binuclear single atom bridged complexes. The UV/VIS spectrum of the mixed Mn–Fe m-nitrido complex 5 m-(MnNFe)(OPTAP)2, Figure 2(c) is similar to the spectrum of the homobinuclear m-nitridodiiron complex m-N(FeOPTAP)2, Figure 2(d), but the maxima of the Q-band envelope are bathochromically shifted.No metal-axial ligand stretching vibrations characteristic of the initial complexes 3 and 4 (nMnºN = 1054 cm–1 for 3 and nFe–Cl = 310 cm–1 for 4) are present in the IR spectrum of 5 and a medium-weak band at 918 cm–1 appears likely to be associated with the MnNFe bridge (FeNFe absorbs at 920 cm–1). The dinuclear identity of 5 has also been confirmed by its reaction with acids HX (HX = HCl, H2SO4, AcOH, CCl3COOH) which causes decomposition to the mononuclear complexes of Mn and Fe (X)MnOPTAP and/or NºMnOPTAP and (X)FeOPTAP, each of which can be separated by thin-layer chromatography and identified by UV/VIS spectroscopy.It has been verified that reaction of NºMnOPTAP with bromoiron(III), acetatoiron(III) and m-oxodiiron(III) derivatives of octaphenyltetraazaporphine (Br)FeOPTAP, (AcO)FeOPTAP and m-O(FeOPTAP)2 also leads to 5.Mixed Mn–Fe m-nitrido species containing dissimilar macrocyclic ligands bound to each metal can be obtained by coupling of the corresponding nitridomanganese(V) and iron(III) complexes, thus reaction of NºMnOPTAP with (AcO)FeTPP gives (OPTAP)Mn(m-N)Fe(TPP).Whether the m-(MnNFe) bridge has an asymmetrical bond distribution (MnIII–N=FeIV or MnIV=N–FeIII as shown in Scheme 2) or its structure is more symmetrical (Mn N Fe) similar to the (Fe N Fe) bridge in m-N(FeOPTAP)2 2 is not yet clear. Physicochemical properties of mixed Mn–Fe m-nitrido complexes of porphyrins as well as details of the mechanism of their formation are presently under investigation.Financial support from the Deutscher Akademischer Austauschdienst (Bonn, Germany) is gratefully acknowledged. We thank Mrs. U. Cornelissen (Christian-Albrechts-Universität zu Kiel, Germany) for FT-IR and resonance Raman measurements and Dr. U. Ziener (Max-Planck-Institut für Polymerforschung, Mainz, Germany) for obtaining the mass spectra. References 1 D. A. Summerville and I.A. Cohen, J. Am. Chem. Soc., 1976, 98, 1747. 2 P. A. Stuzhin, L. Latos-Grazynski and A. Jezierski, Transition Met. Chem., 1989, 14, 341. 3 V. L. Goedken and C. Ercolani, J. Chem. Soc., Chem. Commun., 1984, 378. 4 B. J. Kennedy, K. S. Murray, H. Homborg and W. Kalz, Inorg. Chim. Acta, 1987, 134, 19. 5 C. Ercolani, J. Jubb, G. Pennesi, U. Russo and G. Trigiante, Inorg.Chem., 1995, 34, 2535. (a) (b) (c) 2 1 0 Absorbance 400 600 800 1000 l/nm Figure 1 UV/VIS spectra of (a) (AcO)MnOPTAP in chloroform (3.5×10–5 M); (b) after saturation with ammonia at –20 °C; (c) after bubbling of chlorine. N N N N N N N N Fe Ph Ph Ph Ph Ph Ph Ph Ph N Ph Ph Ph Ph Ph Ph Ph Ph Mn N N N N N N N N NºMnOPTAP (Cl)FeOPTAP 3 4 m-(MnNFe)(OPTAP)2 Scheme 2 5 benzene reflux Figure 2 UV/VIS spectra of (a) NºMnOPTAP; (b) (Cl)FeOPTAP; (c) m-(MnNFe)(OPTAP)2 and (d) m-N(FeOPTAP)2 in chloroform. (a) (b) (c) (d) 104e 8 6 4 2 400 600 800 l/nm ... ... ... ...Mendeleev Communications Electronic Version, Issue 5, 1997 (pp. 169–212) 6 J. W. Buchler and C. Dreher, Z. Naturforsch., 1984, 39b, 222. 7 W.-D. Wagner and K. Nakamoto, J. Am. Chem. Soc., 1988, 110, 4044. 8 J. W. Buchler, C. Dreher and K. L. Lay, Z. Naturforsch., 1982, 37b, 1155. 9 H. Grunewald and H. Homborg, Z. Naturforsch., 1990, 45b, 483. 10 P. A. Stuzhin, M. Hamdush and U. Ziener, Inorg. Chim. Acta, 1995, 236, 131. 11 M. J. Camenzind and C. L. Hill, Inorg. Chim. Acta, 1985, 99, 63. Received: Cambridge, 2nd May 1997 Moscow, 3rd June 1997; Com. 7/02979I