Actinide porphyrin complexes

Miscellaneous · Sun Jan 01 00:00:00 EST 1989

OSTI ID:5611937

Milam, S N

The first bis(porphyrin)actinide complexes have been prepared by reaction of M(NEt{sub 2}){sub 4} (where M = Th, U) with H{sub 2}TPP or H{sub 2}OEP. The coordination geometry of (TPP){sub 2}Th is a distorted square-prism where the thorium center is displaced 1.47 {angstrom} from each of the porphyrin N{sub 4} planes; the porphyrin planes are separated by 2.94 {angstrom}. The porphyrin macrocycles, held in such close proximity, interact electronically as shown by a shift in the porphyrin Soret band to higher energy and unusually facile oxidation processes relative to related monoporphyrin complexes. Oxidation of (TPP){sub 2}M yields porphyrin-based radical cation complexes ((TPP){sub 2}M{sup +})(SbCl{sub 6}{sup {minus}}) and dicationic complexes, ((TPP){sub 2}M{sup 2+}) (SbCl{sub 6}{sup {minus}}){sub 2}. The porphyrin planes of ((TPP){sub 2}Th{sup +})(SbCl{sub 6}{sup {minus}}) are separated by 2.89 {angstrom}, this separation is slightly less than that of (TPP){sub 2}Th. The EPR spectrum of ((TPP){sub 2}Th{sup +})(SbCl{sub 6}{sup {minus}}) is that of a simple organic radical (g = 2.0016) while the uranium complex shows unusual signals at g{sub para} = 3.175 and g{sub perp} = 1.343. SQUID measurements on ((TPP){sub 2}Th{sup +}) (SbCl{sub 6}{sup {minus}}) suggest that above 70 K there are thermally populated excited state(s) with f-orbital character. Above 200 K, ((TPP){sub 2}U{sup +})(SbCl{sub 6}{sup {minus}}) apparently adopts S = 3/2 spin state(s), but below 70 K the spin state appears to be S = 1/2. This behavior may be due to antiferromagnetic coupling of the porphyrin radical to the f{sup 2} U{sup IV} center. The dicationic complex ((TPP){sub 2}Th{sup 2+})(SbCl{sub 6}{sup {minus}}){sub 2} is essentially diamagnetic.

• Research Organization: Illinois Univ., Urbana, IL (USA)
• OSTI ID: 5611937
• Resource Relation: Other Information: Thesis (Ph. D.)
• Country of Publication: United States
• Language: English

Related Subjects

63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
PORPHYRINS
BIOSYNTHESIS
THORIUM
METABOLISM
URANIUM
COMPLEXES
RADIONUCLIDE KINETICS
ACTINIDES
CARBOXYLIC ACIDS
ELEMENTS
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
METALS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
SYNTHESIS
560161* - Radionuclide Effects
Kinetics
& Toxicology- Man