Bimetallic (Et4N)2[Co2(L)2], (Et4N)2[1] (where (L)3– = (N(o-PhNC(O)iPr)2)3–) reacts with 2 equiv of O2 to form the monometallic species (Et4N)[Co(L)O2], (Et4N)[3]. A crystallographically characterized analog (Et4N)2[Co(L)CN], (Et4N)2[2], gives insight into the structure of [3]1–. Magnetic measurements indicate [2]2– to be an unusual high-spin CoII-cyano species (S = 3/2), while IR, EXAFS, and EPR spectroscopies indicate [3]1– to be an end-on superoxide complex with an S = 1/2 ground state. By X-ray spectroscopy and calculations, [3]1– features a high-spin CoII center; the net S = 1/2 spin state arises after the Co electrons couple to both the O2•– and the aminyl radical on redox non-innocent (L•)2–. Dianion [1]2– shows both nucleophilic and electrophilic catalytic reactivity upon activation of O2 due to the presence of both a high-energy, filled O2– π* orbital and an empty low-lying O2– π* orbital in [3]1–.

Syntheses, structural, and spectroscopic characterization of multinuclear tris(amidate) lanthanide complexes is described. Addition of K3[N(o-PhNC(O)tBu)3] to LnX3 (LnX3 = LaBr3, CeI3, and NdCl3) in N,N-dimethylformamide (DMF) results in the generation of dinuclear complexes, [Ln(N(o-PhNC(O)tBu)3)(DMF)]2(μ-DMF) (Ln = La (1), Ce (2), Nd(3)), in good yields. Syntheses of tetranuclear complexes, [Ln(N(o-PhNC(O)tBu)3)]4 (Ln = Ce (4), Nd(5)), resulted from protonolysis of Ln[N(SiMe3)2]3 (Ln = Ce, Nd) with N(o-PhNCH(O)tBu)3. In the solid-state, complexes 1–5 exhibit coordination modes of the tripodal tris(amidate) ligand that are unique to the 4f elements and have not been previously observed in transition metal systems.

The ligand bis(2-isobutyrylamidophenyl)amine has been prepared and used to stabilize both mononuclear and dinuclear cobalt(II) complexes. The nuclearity of the cobalt product is regulated by the deprotonation state of the ligand. Both complexes catalytically oxidize triphenylphosphine to triphenylphosphine oxide in the presence of O2.

A diiron(II) complex containing two μ-1,3-(κN:κO)-amidate linkages has been synthesized using the 2,2′,2′′-tris(isobutyrylamido)triphenylamine (H3LiPr) ligand. The resulting diiron complex, 1, reacts with dioxygen (or iodosylbenzene) to effect intramolecular C–H bond activation at the methine position of the ligand isopropyl group. The ligand-activated product, 2, has been isolated and characterized by a variety of methods including X-ray crystallography. Electrospray ionization mass spectroscopy of 2 prepared from18O2 was used to confirm that the oxygen atom incorporated into the ligand framework is derived from molecular oxygen.

First-row transition metal-halide complexes of tris(2-dimethylaminophenyl)amine, LMe, have been synthesized and characterized. X-ray crystallographic studies on [Co(LMe)Br]BPh4, [Ni(LMe)Cl]BPh4, [Fe(LMe)Cl]BPh4, and [Cu(LMe)Cl]BF4 have been performed, and in all cases the ligand produces five-coordinate complexes with distorted trigonal bipyramidal coordination geometries. Where possible, comparisons have been made to the structures of related neutral tripodal ligands. Spectroscopic and magnetic studies of these complexes are also described. The Cu(I)-carbonyl complexes [Cu(LMe)(CO)]PF6 and [Cu(Me6tren)(CO)]PF6 (Me6tren = tris(N,N-dimethylaminoethyl)amine) have also been prepared. Infrared spectroscopic investigations of these carbonyl complexes confirm that LMe is a less electron donating ligand than Me6tren and indicate that LMe can impart a different coordination number in the solid-state.

The ligand bis(2-isobutyrylamidophenyl)amine has been prepared and used to stabilize both mononuclear and dinuclear cobalt(II) complexes. The nuclearity of the cobalt product is regulated by the deprotonation state of the ligand. Both complexes catalytically oxidize triphenylphosphine to triphenylphosphine oxide in the presence of O2.