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Inorganic Chemistrytriazole)copper(II) ( J / k = -17.9 to -19.O"K) than in ligand atoms of dichloro(l,2,4-triazole)copper(II).13 copper(I1) benzoate trihydrate ( J / k = -12.7'K), deThus, although normal magnetic moments have been spite the fact that the Cu-Cu distance of 3.40 A in the observed for these compounds a t room temperature, former is longer than 3.15 A in the latter. Therefore, the spins are not free from one another, but antiferrothe superexchange interaction rather than the intermagnetic interaction exists between neighboring spins action of direct nature is predominant. This conchin a chain. sion is supported by the existence of spin densities in the (16) M . Inoue and &I, x7torg. them., 5, 70 (1066).The repulsion between the lone electron pairs of the nitrogen atoms in the staggered hydrazine molecule influences the length of the nitrogen-nitrogen bond; diminution of the repulsion causes shortening of the bond in those derivatives of hydrazine where the lone pair is attracted to bonds. the shifts of v(h--N) are in agreement with this point of view. The band shifts from 880 toward 1000 cm-' when the repulsion between the lone pairs diminishes. I n metal complexes of hydrazine, shifts of the band are also observed, depending on the field effect of the metal cations on the lone pairs, even if the nitrogen-nitrogen bond distance remains unaltered.The infrared spectra of several hydrazine derivatives have been examined:The hydrazine molecule H2N-NH2 is composed of two tetrahedra in staggered configuration, 1, one corner in each being occupied by a lone pair. The nitrogennitrogen boiid distance is N-N = 1.46 A3 in solid hydrazine but it becomes shorter in the cation +H3N-

The complex Cp*Zr(2,6-OC 6 H 3 t Bu 2 )Cl 2 (Cp* ) η 5 -C 5 Me 5 ) (1) has been prepared by the reaction of the starting material Cp*ZrCl 3 and 1 equiv of the lithium salt of the phenol compound. The reactions of 1 and the appropriate Grignard reagents afford the alkyl derivatives Cp*Zr(2,6-OC 6 H 3 t Bu 2 )Me 2 (2) and Cp*Zr(2,6-OC 6 H 3 t Bu 2 )(Bz)(Cl) (3). This and other dimethyl derivatives, namely, Cp*Zr(2,6-OC 6 H 3 Me 2 )Me 2 (4), Cp*Zr(O-2-t Bu-6-MeC 6 H 3 )-Me 2 (5), and Cp*Zr(O-2-C 3 H 5 -6-MeC 6 H 3 )Me 2 (6), can be obtained by reaction of Cp*ZrMe 3 and the corresponding phenol. When an excess of the less bulky 2,6-Me 2 C 6 H 3 OH phenol was used, the completely substituted complex Cp*Zr(2,6-OC 6 H 3 Me 2 ) 3 (7) was obtained. The reactivity of Cp*Zr(2,6-OC 6 H 3 t Bu 2 )Me 2 in the insertion process of isocyanide compounds was studied. In all cases, the corresponding η 2 -iminoacyl compounds, Cp*Zr(2,6-OC 6 H 3 t Bu 2 )(η 2 -MeCdNR)(Me) [R ) Xy (8); n Bu (9), Cy (10), TMB ) 1,1,3,3-tetramethylbutyl (11)], were obtained. Similar reactivity was found for Cp*Zr(2,6-OC 6 H 3 t Bu 2 )(Bz)(Cl) and Cp*Zr(O-2-t -Bu-6-MeC 6 H 3 )Me 2 . The complexes were characterized by spectroscopic methods, and in some cases, variable-temperature 1 H NMR spectroscopy studies were carried out. In addition, the molecular structure of Cp*Zr(2,6-OC 6 H 3 Me 2 ) 3 has been determined by X-ray diffraction methods. Finally, complexes Cp*Zr(2,6-OC 6 H 3 t Bu 2 )Cl 2 and Cp*Zr(2,6-OC 6 H 3 Me 2 ) 3 were tested as ethylene polymerization catalysts in the presence of MAO as cocatalyst. While the former complex shows a high activity similar to that found for classical metallocene catalysts, the latter is much less active. The different activities found for these complexes can be explained in terms of the different activation processes.

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The crystal structure of carbohydrazide, OC(NH-NH2)2, has been determined from X-ray intensity data (Cu K~ radiation) measured with an automatic diffractometer. The space group is P2~/e with unit-cell dimensions a=3.728 (2), b=8.841 (3), c=12-659 (7) A; fl= 109-1 (1) °, V=394.3 /~3, Z=4. The structure was solved by the symbolic addition procedure and refined by the full-matrix least-squares method to R = 4 %. The molecule, depending upon rotations around the bonds C-N and N-N, has one -NH-NH2-group in cis, gauche position (cis position with respect to C-O, with -NH2 in gauche position with respect to C-N) and the second group -NH-NHz in trans, antigauche position. The different conformational orientations do not alter appreciably bond distances and angles. The group of atoms N-CO-N is planar, with bond distances and angles practically equal to those in urea. One hydrogen bond -NH... NH2-= 2.950/~, joins the molecules in chains parallel to [001] and weak hydrogen bonds, both N... O and N... N, connect the chains.