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elusion is found in an examination of the geometry of the perchlorate group (Tables III and IV). The three Cl-0 distances not involving 0(2) are 1.383 (7), 1.392 (5), and 1.392 (5) A, with an average value of 1.389 (5) A; the Cl-0(2) distance of 1.434 (5) A is significantly longer than these three, as would be expected if 0(2) were involved in hydrogen bonding to the bridge. A view of the perchlorate anion and its probable interaction with the bridge is shown in Figure 2.The Cu-O-Cu bridging angle, , is 103.0 (2)°. The best unweighted least-squares line through the five available values of and 2/ for di-/r-hydroxo-copper(II) dimers has an intercept of 7730 cm'1 and a slope of -79.1 cm"1 deg"1. Using the published4 value for 2/of -410 cm"1, the predicted value of is 102.9 (1)°, which is in remarkable agreement with the observed angle. Evidently, therefore, the present structural data strongly support the hypothesis that, over the angular range 95°< < 105°, there is a linear relationship between and J. In the light of this observation, it should now be possible to predict J from or vice versa for this class of complexes.Registry No. [Cu(teen)0H]1(C104)1, 51259-55-3. Supplementary Material Available. A listing of structure factor amplitudes will appear following these pages in the microfilm edition of this volume of the journal. Photocopies of the supplementary material from this paper only or microfiche (105 X 148 mm, 24X reduction, negatives) containing all of the supplementary material for the papers in this issue may be obtained from the Journals

Structure of Cu2 (CF3CN4)2 ((CH2P (CeH6) 2) 2);

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Hedaya and L. Skattebol for their stimulating discussions and kind supply of 2-and 4-iodopyridines.Crystal and Molecular Structure of Bis (dimethylglyoximato) diimidazoleiron (II) -Dimethanol