The preparation and characterization of the -oxochlorin derivative [3,3,7,8,12,13,17,18-octaethyl-(3H)-porphin-2-onato(2-)]copper(II), [Cu(oxoOEC)], and its π-cation radical derivative, [Cu(oxoOEC • )][SbCl 6 ], are described. Both compounds have been characterized by single-crystal X-ray structure determinations; IR, UV/vis/near-IR, and EPR spectroscopies; and temperature-dependent magnetic susceptibility measurements. Crystals of [Cu-(oxoOEC)] have two crystallographically distinct molecules, one at a general position ([Cu(oxoOEC)]-gen) and a second at a special position ([Cu(oxoOEC)]-spe). [Cu(oxoOEC)]-gen has a S 4 -saddled conformation whereas [Cu(oxoOEC)]-spe has a modest ruffled conformation. [Cu(oxoOEC • )][SbCl 6 ] shows a cofacial dimeric unit in the solid state, with a mean plane separation of 3.41 Å and a lateral shift of 5.47 Å. Crystal data for [Cu-(oxoOEC)]: monoclinic, space group C2/c, Z ) 12, a ) 38.404(8) Å, b ) 14.692(6) Å, c ) 16.977(11) Å, ) 101.46(2)°. Crystal data for [Cu(oxoOEC • )][SbCl 6 ]: triclinic, space group P1 h, Z ) 2, a ) 13.063(1) Å, b ) 14.108(2) Å, c ) 11.486(2) Å, R ) 93.77(3)°, ) 102.17(1)°, γ ) 74.07(1)°. The EPR spectrum of [Cu-(oxoOEC • )][SbCl 6 ] in frozen dichloromethane at 77 K shows the characteristics of a dimeric copper(II) triplet state. Two broad, concentration-dependent near-IR "dimer bands" appear at 1285 and 1548 nm for [Cu(oxoOEC • )]-[SbCl 6 ]. Solid-state magnetic susceptibility measurements for [Cu(oxoOEC • )][SbCl 6] resulted in a large temperature dependence of the magnetic moments that can best be fit with a four-spin model. This model includes antiferromagnetic intermolecular copper-copper coupling (2J Cu-Cu ) -70 cm -1 ), antiferromagnetic radical-radical coupling (2J r-r ) -139 cm -1 ), and ferromagnetic intramolecular copper-radical coupling (2J Cu-r ) 139 cm -1 ).

Recently there has been much concern with the ability of plants to uptake heavy metals from their surroundings. With the development of instrumental techniques with low detection limits such as inductively coupled plasma-mass spectrometry (ICP-MS), attention is shifting toward achieving faster and more elegant ways of oxidizing the organic material inherent in environmental samples. Closed-vessel microwave dissolution was compared with conventional methods for the determination of concentrations of cerium, samatium, europium, t sr b' ium, uranium and thorium in a series of samples from the National Institute of Standards and Technology and from fields in Idaho. The ICP-MS technique exhibited detection limits in partsper-trillion and linear calibration plots over three orders of magnitude for the elements under study. The results obtained by using nitric acid and hydrogen peroxide in a microwave digestion system for the analysis of reference materials showed close agreement with the accepted values.These values were compared with results obtained from dry-and wet-ashing procedures. The findings from an experiment comparing radiometric techniques for the determination of actinide elements to ICP-MS are reported. DISCLAIMERThis report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor my of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof. INTR0DC:CTIONAs a result of ongoing industrial pollution and the vital role of plants in the food chain, interest has increased in the ability of plants to uptake potentially hazardous heavy metals from their surroundings. Much attention has also been given to the field of radiological safety, including the determination of small amounts of actinide elements in botanical tissues, as a component of individual contamination-monitoring problems (1). Because environmental samples have large amounts of organic matrix elements but may have low concentrations of the rare earth elements, a digestion procedure whereby the organic matrix is oxidized, leaching the metals from the matrix, must be coupled with an instrumental technique with characteristically low limits of detection.Problems typically arising from the determination of elements in environmental samples are not associated with the efficiency of the instrumental method, but rather ...

The preparation and characterization of a mixed-valence π-cation radical derivative of an iron(III) oxochlorinato complex is reported. The new complex has been synthesized by the one-electron oxidation of a pair of [Fe(oxoOEC)(Cl)] molecules to form the dimeric cation [Fe(oxoOEC)(Cl)]+2. The cation has been characterized by an X-ray analysis, Mössbauer spectroscopy, UV-vis and near-IR spectroscopy, and magnetic susceptibility measurements from 6–300 K. The crystal structure shows that the two rings have a smaller overlap area that those of the formally related nickel and copper octaethylporphyrinateethylporphinate derivatives, reflecting the larger steric congestion at the periphery in part of the oxochlorin rings. The Mössbauer data is consistent with two equivalent iron(III) centers. The unpaired electron is delocalized over the two oxochlorin rings and mediates a strong antiferromagnetic interaction between the high-spin iron(III) centers.

This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, make any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof. ' 1' .-tbstrucf: Treatment of [Fe(OEP)!20 with trichloroacetic acid (?.%€old excess) resu!ts in the formation of (octaethylporphinato)(trichloroacetatojiron(II1). Various crystalline solvates can be isolated, depending on the crystallization solvent. Initial crystallization with CHCI.3 ,'hexanes resulted in the isolation of an unsoivated form. jFe(OEP,~(02C~C13)]. This form contains m o distinct porphyrin core conformations at the same !attice j&: one is domed and the other i : ruffled. Crystal data for iFe(OEP)(02C?C13)]: Q = 14.754(4) .I. b = 13.674(1)-4. c = 11.5411 j i-4. 3 = 90.6i'(1)3, V = 3545.3(1-1) A3. monoclinic. space group F21/n. Z =-1. Sub:equenr crystallizations with CHCl3/hexanes resulted in a new crystalline form. [ F e (O E P) (O~C~C l~) ]-CHC13; the porphyrin core is slightly rufffed. Crystal data €or [Fe(OEP)(O?C2C13)]CHC13: a = 12.323(1). A. b = 13.062(3) .A. c = 11.327(2) .A, Q = 89.32(1)". 3 = 113.36(2)". 1 ' = 105.26(1)'. V = 2031.3(6)-A3. triclinic. space group Pi. Z = 2. Crystallization with CH2Clz/hexanes resulted ed in the isolation of-et another form, [Fe(OEP)(O?CzC13)].H02C2C13. which contains two independent molecules in the unit cell: molecule A is slightly saddled and molecule B is modestly ruffled. Crystal daJa for [Fe(OEP)(02CzC13)].H02C2C13: a = 13.148(3)-4, b = 13.155(3) .A, c = 23.761(5). A, CY = 90.72(3)". 3 = 91.24(3)". 7 = 92.36(3)", V = 4198.5(15) .A3, triclinic. space group Pi, Z = 4. All conformations form r-7 dimers in the solid state. Temperaturedependent magnetic susceptibility measurements showed that [Fe(OEP)(O?C&33)].CHC13 contains a high-spin iron(II1) center; the data for [Fe(OEP)(02C2C13)1.HO?C~C13 are understood in terms of an admixed intermediate-jpin state (S = 3j2, 5/2) and are readily fit to a Maltempo model with a ground state multiplet containing about 78% S = 5/2 character and 22% S = 3/2 character. The structural data for [Fe(OEP)(02C2Cl3)]-CHCl3 are consistent with the observed high-spin state, while data for iFe(OEP)(02C2C13)]-H02C2C13 are consistent with the admixed-spin iron(lI1) character. The observed core conEormations have been described by a normal-coordinate structural decomposition meth...