CHEMISTRY OF (OCTAETHYLPORPHYRINATO)LUTETIUM AND (OCTAETHYLPORPHYRINATO)YTTRIUM COMPLEXES - SYNTHESIS AND REACTIVITY OF (OEP)MX DERIVATIVES AND THE SELECTIVE ACTIVATION OF O2 BY (OEP)Y(MU-ME)2ALME2

Reaction of ML3 (M = Lu, Y; L = CH(SiMe3)2, O-2,6-C6H3(t)Bu2) with octaethylporphyrin (OEPH2) affords (OEP)ML complexes [M = Lu (1a), Y (1b), L = CH(SiMe3)2; M = Lu (2a), Y (2b), L = O-2,6-C6H3(t)Bu2]. The crystal structure of (OEP)LuCH-(SiMe3)2 (1a) shows a highly dished porphyrin skeleton with the square-pyramidal, five-coordinate lutetium atom 0.918 angstrom out of the N4 plane of the porphyrin ligand. Crystal data: monoclinic, P2(1)/c, a = 14.879 (6) angstrom, b = 20.644 (10) angstrom, c = 14.161 (5) angstrom, beta = 96.38 (3)-degrees, Z = 4, T = 200 K, and R = 0.045 (4098 reflections with I greater-than-or-equal-to 2-sigma(I)). Alkyl species 1 undergo facile protonolysis with HO-2,6-C6H3(t)Bu2, HCC(t)Bu, or H2O to give monomeric alkoxide, dimeric alkynyl, and dimeric hydroxide species [(OEP)MX]n (n = 1, 2) [M = Lu, Y; X = O-2,6-C6H3(t)Bu2 (2a,b), CC(t)Bu (3a,b), OH (4a,b)], respectively. Titration of (OEP)M(mu-OH)2M-(OEP) (4) with H2O affords water adducts (OEP)M(mu-OH)2(H2O)xM(OEP). A synthetically more convenient route to 1 is via reaction of 2 with LiCH(SiMe3)2. In marked contrast to the facile hydrogenation of Ln(C5Me5)2CH(SiMe3)2, alkyl species 1 do not undergo sigma-bond metathesis with H2 (20 atm, 25-degrees-C, C6D12). Reaction of (OEP)YOC6H3(t)Bu2 (2b) with MeLi (2 equiv) in ether affords ether-insoluble (OEP)Y(mu-Me)2Li(OEt2) (5). Treatment with AlMe3 (2 equiv) in hexane yields monomeric, highly fluxional (OEP)Y(mu-Me)2AlMe2 (6), which selectively activities O2 to afford (OEP)Y(mu-OMe)2AlMe2 (7). Comparison of the reactivity of these species, particularly 1 and 6, with their C5H5 and C5Me5 counterparts is described. O-17 NMR data on labeled 4a, 4b, and 7 are presented and discussed.