3562 Inorg. Chem. 1987, 26, 3562-3568 Contribution from the Department of Chemistry, University of California, Davis, California zyx 956 16 Insertion of Manganese and Cobalt into Octaethylporphyrin N-Oxide. Formation of Layered Diporphyrin Structures Joined through M-0-N Links Ramesh D. Arasasingham, Alan L. Balch,* Marilyn M. Olmstead, and Mark W. Renner Received May 28, 1987 Treatment of octaethylporphyrin N-oxide (OEPH2-N-O) with manganese(I1)acetate or cobalt(I1) acetate in ammoniacal methanol produces the cations [(OEP)M1"(OEPH2-N-O)]+ (OEP is octaethylporphyrin dianion), which have been isolated as the acetate, chloride, or hexafluorophosphate salts. zyxwvuts [(OEP)Mn"'(OEPH2-N-O)]CH3COO-3CH2C12 crystallizes in the triclinic space group PI (No. 2) with a zyxwvutsrqp = 10.224 (2) A, b = 12.329 (2) A, c = 15.021 (2) A, zyxwvu a = 77.18 (2)O, zyxwv 0 = 86.88 (2)O, y = 82.45 (2)O, and 2 = 1 at 130 K. The structure was refined to zyxwvutsrqp R = 0.087 for 446 parameters and 4764 reflections. [(OEP)Co1I1(NH3)- (OEPH2-N-O)][CoC14]o.5.1 .5CH2CI2 crystallizes in the monoclinic space group P2,/c (No. 14) with zyxwv a = 18.566 (9) A, b = 14.405 (9) A, c = 28.688 (16) A, 0 = 105.31 (2)O, and Z = 4, at 130 K. The structure was refined to R = 0.106 with 505 parameters and 4818 reflections. Both cations consist of a metal bound to a normal octaethylporphyrin with a monodentate 0-bound OEPH2-N-0as an axial ligand. The Mn(II1) complex is five-coordinate (Mn-N = 1.977-2.125 A, Mn-0 = 2.070 8, with Mn 0.148 A out of plane) while the Co(II1) complex is six-coordinate with an axial ammonia ligand (Co-N,, = 1.971-1.993 A, Co-NH, = 1.961 A, Co-0 = 1.976 A with Co 0.035 A out of plane toward 0). Spectroscopic data (UV/vis, 'H NMR, and mass spectra) that confirm the structures are reported. The Mn(II1) complex is high spin with p = 4.70 pe at 296 K. Introduction Octaethylporphyrin N-oxide (1; OEPH,-N-0) contains a crowded central core that is occupied by the two pyrrole protons 1 2 and an oxygen atom that is bound to one pyrrole nitrogen (N-O distance 1.398 (7) A) and placed 1.0 A above the porphyrin Insertion of nickel(I1) or copper(I1) into 1 produces the complexes 2,334 in which the metal ions are bound to a nearly planar set of three nitrogen atoms and one oxygen atom. Com- plexes of type 2 are of current interest as models for the highly reactive and highly oxidized forms of heme enzymes and as po- tential intermediates in heme metab~lism.l-~Because of the geometric constraints necessary to accommodate both a metal and an oxygen atom within the center of a porphyrin, there may be limitations on the size of metal ions that can assume structure 2. In order to investigate the range of metal ions that can be inserted into 1, we have extended our previous studies to the insertion of cobalt and manganese into 1. Here we report the preparation and structural characterization of two related cations consisting of a porphyrin N-oxide bound to a normal metallo- (1) Bonnett, R.; Ridge, R. J.; Appelman, E. H. J. Chem. zyxwvutsrq Soc., Chem. Commun. 1978, 310. (2) Andrews, L. E.; Bonnett, R.; Ridge, R. J.; Appelman, E. H. J. Chem. Soc., Perkin Trans. 1 1983, 103. (3) Balch, A. L.; Chan, Y. W.; Olmstead, M. M.; Renner, M. W. J. Am. Chem. SOC. 1985, 107, 2393. (4) Balch, A. L.; Chan, Y. W.; Olmstead, M. M. J. Am. Chem. Soc. 1985, 107, 6510. (5) Chewier, B.; Weiss, R.; Lange, M.; Chottard, J. C.; Mansuy, D. J. Am. Chem. SOC. 1981, 103,2899. (6) Latos-Grazynski, L.; Cheng, R. J.; La Mar, G. N.; Balch, A. L. J. Am. Chem. SOC. 1981, 103, 4270. (7) Tatsumi, K.; Hoffmann, R. Inorg. Chem. 1981, 20, 3771. (8) Olmstead, M. M.; Cheng, R. J.; Balch, A. L. Inorg. Chem. 1982, 21, 4143. (9) Strich, A.; Veillard, A. Now. J. Chim. 1983, 7, 347. porphyrin (obtained by deoxygenation of 1). Results Insertion Reactions. Treatment of 1 with cobalt acetate in methanol/ammonia at 25 OC using conditions similar to those reported for the formation of the copper complex 2b produces the brown cation 4, which has been isolated in 47% yield. This c L cation3. M =Mn. L=nothing cation4,M=Co. L=NH3 complex has also been prepared by adding 1 to CoOEP under aerobic conditions. The manganese complex 3 has been obtained under somewhat more vigorous metalation conditions (heating under reflux in methanol for 24 h) in 57% yield. Although divalent metal ions were used in the metalation procedure, the physical characteristics of the complexes indicated that Co(II1) and Mn- (111) compounds result. While we have not undertaken identi- fication of the oxidizing agent, two likely sources are present. One is 1 itself, while the other is dioxygen, which is present at several stages during the preparation. However, it is certain that the normal porphyrin component of 3 and 4 comes from deoxygenation of 1; the samples of 1 that we used contained less than 2% OEPHz as impurity by IH N M R spectroscopy. This deoxygenation process could serve to oxidize the divalent metal ions during the metalation process. X-ray Crystal Structure of [(OEP)Mn(OEPH,-N-0) 1- (CH3C00).3CHzCl2 (3). Table I gives the atomic positional parameters, while Tables I1 and I11 give selected interatomic distances and angles. The cation has a disordered structure. Figure 1 shows a view of the entire cation of 3. It is composed of two porphyrin units packed about a center of symmetry. Figure 2 shows the porphyrin itself and our numbering system. The disorder involves the position of the manganese, oxygen, and two inner pyrrole protons. The manganese atoms are present in each porphyrin at 0.50 occupancy. The oxygen atom is also disordered and occupies sites O( 1) and O( 1)' with 0.50 occupancy. Finally, two hydrogen atoms (shown in Figure 1 but not shown in Figure 2) are bound to N(2) and N(4), and each has 0.50 occupancy. Combining these two units by placing one manganese in one 0020-1669/87/1326-3562$01.50/0 0 1987 American Chemical Society