A new class of complexes possessing cofacially-oriented, planar, metal-containing subunits.: Synthesis, characterization, and reactivity of [(MoO2)2(μ-O)]2+-linked, catechol-functionalized, tetraazamacrocyclic and salicylideneamine complexes

A new synthetic route to molecules that contain cofacially oriented, [Mo2O5](2+)-bridged bis(catecholate) dianions is described. This synthesis has been useful in the preparation of supermolecular molecules containing catechol-functionalized, metalated macrocyclic [M-II(TAD(OH)(2))] (M = Co, Ni) and SALPHEN [M-II(R2R'(2)SALPHEN(OH)(2))] (M = H-2, Mn, Fe, Co, Ni, Cu) ligands. Of the former, the (Bu4N)(2)[Mo2O5[Ni(TAD(O)(2))](2)] (7) complex has been structurally characterized. The complex crystallizes in the triclinic space group P (1) over bar with unit cell dimensions a 12.324(3) Angstrom, b = 17.740(4) Angstrom, c = 20.920(4) Angstrom, alpha = 108.79(3)degrees, beta = 98.20(3)degrees, and gamma = 103.12(3)degrees. The nearly-planar macrocyclic ligands are essentially parallel, with a dihedral angle of 6.5(2)degrees. The Ni(1)--Ni(2) separation in the anion is 3.938 Angstrom. The structure of (Bu4N)(2)[Mo2O5[Cu(EtO(2)H(2)SALPHEN(O)(2))](2)] (19) has also been determined. This complex crystallizes in the monoclinic space group P2(1)/c, with unit cell dimensions a = 20.821(4) Angstrom, b = 23.133(5) Angstrom, c = 20.056(4) Angstrom, and beta = 117.71(3)degrees. The Cu(1)--Cu(2) separation is 4.110 Angstrom, and the dihedral angle between SALPHEN "planes" is approximately 9.7(1)degrees. Analytical and spectroscopic properties are provided. Reactions of these molecules with oxidants and strongly coordinating ligands are presented. The ability of the Fe-II and Co-II analogues of 19 to bind ligands such as O2- or S2- and O-2, respectively, in the "pocket" of the complex is described, and the products have been characterized. The synthesis and characterization of the unique "mixed catecholate" complexes (Bu4N)(2)[Mo2O5((DBC)-B-t)(M-II((t)Bu(4)SALPHEN(O)(2)))] (M = H-2, Fe, Co, Ni, Cu) is described, and comparisons between these latter systems and the bis(M-II-SALPHEN-catecholate) complexes are provided.