High valent manganese and cobalt complexes of oxidatively robust nitrogen and oxygen donor ligands

The focus of this thesis is to extend the range of ligands that satisfy the Collins criteria through a program of organic synthesis, and to apply the resulting high valent metal ligand complexes to the solution of current problems in structural inorganic chemistry, solid state chemistry (with a particular emphasis on magnetic interactions in solids) and to homogeneous and heterogeneous catalysis.; Notable achievements along these directions to date are: (i) A streamlined synthesis of diamide dialkoxide and diamide diphenoxide acyclic ligands which allows for a wide range of both electron withdrawing and electron donating substituents to be incorporated into the ligand framework. (ii) The first example of a LMn(V)O species stable enough to be crystallographically characterized was obtained, utilizing the acyclic ligands of (i). (iii) Catalytic O-atom transfer oxidations utilizing acyclic ligands from (i) have been performed. Planar Co(III) complexes of these ligands can catalyze O-atom transfers,{dollar}sp1{dollar} with 30-50 turnovers, including enantioselective ones,{dollar}sp2{dollar} implicating that the ligands remain at least partially intact during the catalytic process. (iv) Unusual magnetic ordering has been observed in an infinite linear chain of S = 2 LMn(III) centers, in collaboration with Edmund P. Day. (v) Ferromagnetic exchange has been obtained in a ((LCo(III)) {dollar}sb3{dollar}Co(II)) {dollar}sp{lcub}-{rcub}{dollar} complex{dollar}sp4{dollar} Magnetic model building in collaboration with Gordon Yee and Emile Bominaar has led to an understanding of the magnetic data suitable for publication.{dollar}sp5{dollar} (vi) Adaptation of a range of electronic substituents (see (i)) into a macrocyclic framework{dollar}sp7{dollar} allows for the preparation of hydrolytically and oxidatively stable high valent metal complexes. The presence of a range of electronic substituents further allows redox potentials for a single (LM) {dollar}sp{lcub}rm n+{rcub}{dollar}/(LM) {dollar}sp{lcub}(rm n+1)+{rcub}{dollar} oxidation process to be tuned over a range that spans ca. 1 V. (vii) Initial linear syntheses for these macrocycles involved the use of organic azide intermediates. (viii) A new macrocyclic switching ligand has been synthesized utilizing (vii), that allows H{dollar}sp{lcub}+{rcub}{dollar} or other lewis acids to act at the secondary site as electron withdrawing groups from the metal. In the structurally characterized switching (Co(III)({dollar}kappasp4{dollar}-L)) {dollar}sp{lcub}-{rcub}{dollar} complex, there is a bidentate switching site consisting of a pyridine-N and an adjacent amide-O donor. It has been found that the cobalt(II) derivative (CO(II)({dollar}kappasp4{dollar}-L)) {dollar}sp{lcub}-{rcub}{dollar} readily reduces O{dollar}sb2{dollar} by an outer sphere (presumably by 1 e{dollar}sp{lcub}-{rcub}{dollar}) process. (ix) Robust homogeneous metalloredox-active oxidants are an important strategic goal for primary pollution prevention, or what is often called "green chemistry". Use of (vii) provides access to quantities of a macrocyclic ligand, that is derivatized in such a way that it can be attached to a solid polymer support. (x) C-H bond activation has been observed in iron systems{dollar}sp{lcub}15{rcub}{dollar} in collaboration with Mike Bartos (the principal investigator) where use of (vii) has allowed quantities of ligand to be synthesized and burned in reaction chemistry with nitriles and oxidants. (xi) Macrocyclic ligands with organic solubilizing groups have been prepared utilizing (vii) and metal complexes with substantial alkane solubility result. (Abstract shortened by UMI.)...