NOTES 491were found to be monomeric and both exhibited normal magnetic moments. The visible spectrum of the anhydrous material in carbon tetrachloride, Figure 1, shows a well-separated shoulder on the high-energy side of the visible band; the spectrum of the dihydrate in the same solvent shows a less pronounced shoulder much closer to the main band. Since a well-separated shoulder is present on the high-energy side of the main band in the spectra of all other 6-dicarbonyl complexes of copper(II), this shoulder probably results from further splitting of the d orbitals as the symmetry is decreased from octahedral to square-planar; such an assignment has been discussed for bis(acety1acetonato)copper(II).' The position of this band, nearer the main band, in the dihydrate spectrum is probably due to a less pronounced tetragonal distortion and, thus, suggests that the waters are coordinated to the copper to give a distorted octahedron.Magnetic circular dichroism (MCD) has been observed for solutions of K2PtC14 in dilute HC1 which provides information relevant to the assignment of energy levels of the square-planar PtC14-2 ion. The energy level scheme of this ion has recently been discussed on the basis of polarized single-crystal spectra recorded a t 15°K.2 The experimental arrangement for the determination of circular dichroism was described earlier.3 Modifications have included : (1) a 30-fold electrical expansion of the recorder scale which does not appreciably alter the signal-to-noise ratio, (2) the replacement of the Jouan monochromator by an Applied Physics Corp. Model 15 monochromator, (3) the use of a 500-w xenon arc light source, (4) a change of the crystal modulation frequency in the dichrograph from 60 to 82 cps, (5) the use of an electromagnet to provide a magnetic field of 12,000 gauss in which the light beam travels from the south toward the north pole. A clockwise rotation for an observation toward the light source is called positive. Under

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