EPR spectra were recorded on a Varian V-4510 or a Bruker B-ER420 instrument, and EPR parameters were evaluated as described. 21 The complexes were determined to be 90 k 10% EPR active by comparison of their EPR signals with the EPR signals from M~OCI(OX)~, which had been calibrated by double integration against the EPR signal from K,Mo(CN),. Samples were prepared under prepurified Nz (99.997%), transferred to 3.0-mm i.d. tubes with the use of gas-tight syringes, and frozen immediately in liquid nitrogen for low-temperature spectra. For room-temperature spectra, samples were transferred to a flat cell that had been evacuated and flushed with N2 and kept under argon until spectra were recorded. Generally, (21) A. Marchesini and P. M. H. Kroneck, Eur. J. Biochem., 101,65 (1979).0.1 M (C2H5),NCI was added to the solutions of the W(V) complexes, approximately 5.00 X Infrared spectra were recorded on a Beckman IR 20 instrument with the use of Nujol mulls.The far-infrared spectra of several iron(II1) dialkyldithiocarbamates having room-temperature magnetic moments in the high-, low-and intermediate-spin range have been reinvestigated. Iron-sulfur stretching vibrations have been assigned with the use of 54Fe and 57Fe isotopes. The high-spin Fe-S stretching vibrations appear at 205-250 cm-' and the low spin at 305-350 cm-', and the intermediate spin show Fe-S stretching bands in both regions. Results of spectral measurements above and below room temperature are explained on the basis of these assignments. A. Welch Foundation (Grant No. R-483) and the ResearchCouncil at Abilene Christian University. We wish to thank the Chemistry Department at the University of Texas at Austin for the use of their Digilab FT-IR. even less upon a change from high-spin-to low-spin. The similarity of the three high-spin Fe-ligand stretching bands implies that the Fe(II1) system does not give as favorable a Registry No. F e ( E t d t~)~, Gd(fod), has a pronounced effect on "C and 'H NMR spin-lattice relaxation rates of [N,N'-ethylenebis(acety1acetone iminato)Jnickel(II) (I) in chloroform solution. A Gd(f~d)~.I adduct is formed which is in rapid equilibrium with its components. The Gd(II1) ion is assumed to bind to both oxygens of I with normal Gd-O bond lengths, and the position of Gd(II1) relative to I is determined from analysis of paramagnetic contributions to the relaxation rates of two carbon atoms. The Gd(II1) ion is located at a point N 1.8 8, out of the plane of I. Distances from Gd(II1) to the other carbon atoms and to the protons are calculated from the appropriate NMR relaxation rates. These distances are compared with those determined with the use of crystallographic data for I and by assuming that Gd(II1) is located correctly by the NMR data. The agreement is within the limits of error in all cases, thus supporting assumptions made in devising the model.

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