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Two sterically hindered tris-pyridyl methane ligands, tris(6-methyl-2-pyridyl)methane (L1) and bis(6-methyl-2-pyridyl)pyridylmethane (L2), are newly synthesized. Under aerobic conditions, Ln (n = 1 or 2) reacts with CuX2 (X = Cl or Br), oxygenated at the methine position to LnOH or LnOMe. The former alcoholate ligand creates trinuclear Cu(II) complexes [Cu3(X)(LnO)3](PF6)2 [(X, n) = (Br, 1) 1, (C1, 1) 2, (Br, 2) 3, or (C1, 2) 4] in which the alkoxide oxygen atoms bridge copper centers. The crystal structures of 1-4 are presented along with their magnetic susceptibility data. The weak antiferromagnetic coupling between the Cu(II) centers in this trinuclear arrangement is due to weak interaction of the magnetic orbitals (dz2) which are oriented along three alternate sides in a hexagon of the Cu3O3 core in 1-4. Under anaerobic conditions, L1 reacts with CuBr2 to form a square pyramidal complex [CuL1Br2] (9) with the ligand facially capping. [Cu(Br)2(L1OMe)] (10) was obtained after the suspension of 9 in MeOH was stirred under air for 48 h. In the presence of cyclohexene, 9 is converted to [Cu(Br)(L1)]m (m = 1 or 2) 5 quantitatively to give trans- 1,2-dibromocyclohexane, indicating that Br2 is generated during the reaction. The FAB MS spectrum of [18O]-1 prepared by the reaction of L1 with CuBr2 under 18O2 shows that the ligand of [18O]-1 is L1(18O-.) L1(18OH), L1OCD3, and bis(6-methyl-2-pyridyl) ketone were obtained from reaction of L1 with CuBr2 in CD3OD under 18O2. These results indicate that the origins of the O atom in L1OH and L1OMe are O2 and MeOH, respectively. On the basis of these results, a mechanism of the oxygenation of L1 in the present system will be proposed.

Heterodinucleating macrocycles with two 2,6-bis(iminomethyl)-4-methylphenolate entities combined through two lateral chains, -(CHz):and -(CH2)mNH(CH2)m-(m = 2,3), at the imino nitrogens have been prepared as CunPbn complexes of the formula [CuPb(L)]XY (L2~= LI for m = 2 and L2 for m = 3; XY = (C104)2, (NOjHPFe), (AcO)(BPh4)). [CuPb(Ll)](AcO)(BPh4)»DMF crystallizes in the monoclinic crystal system, space group P2\/n, with Z = 4, a = 18.890(3) A, b = 19.968(3) A, c = 12.704(2) A, ß « 91.61(1)°, and F= 4790(1) A3. The refinement converges with R = 0.0697 and Fw = 0.0863 for 4945 reflections with |F0| > 3a(|Fo|). The crystal consists of a dimeric cation {CuPb(Ll)(Ac)}22+ bridged by acetate groups, tetraphenylborate ions, and DMF molecules. The Cu is located at the 4-coordination site formed with the ethylene chain and assumes a planar environment. The Pb is at the 5-coordination site formed with the -(CH2)2NH(CH2)2-chain and assumes an eight-coordinate structure also involving three acetate oxygen atoms. The Cu--Pb separation, bridged by two phenolic oxygens, is 3.577(2)A. In the crystal, the dimeric cations further interact through out-of-plane bonding between the {CUN2O2} entities forming a column along the a axis. The [CuPb(Ll)]XY complexes react with metal(II) sulfates to form a series of CunMn complexes, [CuM(Ll)]XY (M = Mn, Fe, Co, Ni, Cu, Zn). [CuMn(Ll)](AcO)(BPh4) crystallizes in the monoclinic space group F2i/n, withZ = 4, a = 17.508(8) A, b = 15.539(5) A, c = 16.515(5) A,j8 = 106.30(3)°, and V = 4312(3) A3. The refinement converges with R = 0.0689 and Rw = 0.0563 for 2935 reflections with |F 3a(|F0|). The Cu(II) and Mn(II) ions reside at the 4and 5-coordination sites of the macrocycle, respectively, and the acetate group bridges the two metal ions providing a nearly square-pyramidal geometry for the Cu and a highly distorted six-coordinate environment for the Mn. The Cu--Mn separation is 3.122(2) A. The cryomagnetic investigations (4.2-300 K) for the CuMn, CuFe, CuCo, CuNi, and CuCu complexes reveal the operation of an antiferromagnetic spin-exchange interaction within each molecule. The cyclic voltammograms of the CuM complexes show Cu(II)/Cu(I) reduction near -0.8 V (vs SCE) and oxidation at the ligand center near +1.3 V. The oxidation of the Fe(II) of the CuFe complex occurs at +0.64 V whereas the Mn(II) ion of the CuMn complex and the Co(II) ion of the CuCo complex are hardly oxidized.