Crystals of the title compound are monoclinic, space group P2Jc with cell dimensions a = 9.439(1), b = 21 -991 (2) c = 12.21 7(1) 8, p = 107.63(1)", and Z = 12. The structure w a s determined from three-dimensional X-ray data collected by counter methods and refined by full-matrix least-squares techniques to R 5.4% for 21 91 observed reflections. Each tellurium atom has a distorted octahedral environment with two iodine atoms in a trans-arrangement, two methyl groups cisto each other, and two contacts from iodine atoms attached to neighbouring molecules. Intramolecular Te-l bonds range from 2.854(3) to 2.994(3) a and Te-C bonds range from 2.10(3) to 2.16(3) 8. The intermolecular Te . . . I contacts range from 3.659(3) to 4. 030(3) 8. Differences in bond lengths and angles can be correlated with the differing distortions in the environment of each tellurium atom. * * * * 1) UlZ Ul, UZ, -0*04(9) 2.25(9) -0*43(10) -0*12(10) 2*77(9) 0.15(10) -0.71(11) 1*64(9) -0.76(12) -0*49(10) 1.62(9) -0.12(9) -0.17( 11) 3*47( 11) -0*76(10) -0*16(8) 0.82(7) -0*19(8) -0.08(8) 1*37(7) -0*12(8) -0.15(8) 1.29(8) -0*73(8) 0*16(10) 2*12(10) 0.37(11) * Anisotropic thermal parameters (A2 x 10') used for iodine and tellurium atoms. contains values for Me,TeCl, 10 for comparison). Standard errors estimated by least-squares procedures and including correlation effects and cell-dimension errors are given in parenthesis. The Figure shows the packing of the molecules within the unit cell viewed down an axis rotated 8" from a* towards a.The motion of the iodine and tellurium atoms is mainly perpendicular to the Te-I bonds. While the anisotropic

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We have determined the molecular structure of the anticancer antiestrogen nafoxidine and compared its three-dimensional structure with two other clinically useful antiestrogens in order to delineate stereochemical parameters in these compounds. Crystals of nafoxidine hydrochloride-ethanol are monoclinic with cell dimensions a = 17.040, b = 7.967, c = 25.260 A, beta = 123.7 degrees, and space group P21/c with four formula units per cell. The structure was solved by direct phasing methods and refined to a discrepancy index of 0.068. The methoxyphenyl and phenyl rings are trans to each other relative to the ethylene bond, and the substituted amine-aryl ether chain has an extended conformation. Stereoscopic superposition drawings and tabular data are given to show structural similarities and difference in nafoxidine, clomiphene, and tamoxifen, the three antiestrogens with with demonstrated clinical efficacy in the management of metastatic mammary carcinoma.

The Ni(II)-S coordinative covalent distance, 2.456 (2) Á, is comparable with the sum of the corresponding Pauling covalent radii,32 2.43 Á, indicating a strong interaction. The corresponding distance in [Ni(PMS)Cl]C104 was found to be 2.472 (5) AT3The octahedral Ni(II) to Brdistance, 2.544 (1) Á, is also approximately the sum of the corresponding Pauling covalent radii,32 2.50 Á, and is close to the reported values of 2.606 (3) Á in dibromodiaquo(A,Ar,Ar',A7'-tetramethyl-ophenylenediamine)nickel(II),33 2.635 (5) Á in dibromotetrakis( 1,8-naphthyridine)dinickel(II) tetraphenylborate,34 and 2.54 Á in iran$-dibromobis(acetylacetone)nickel(II).35The pattern of closest nonbonded contacts is similar to that already discussed for the isostructural [Ni(PMS)Cl]CIO4.13The best defined oxygen, 0(4), is 2.29 Á from an amino hydrogen atom, H(15); and 0(7), next best defined according to the thermal foreshortening of its Cl-O bond length, is 2.39 Á from the other amino hydrogen atom, H(22). See Figure 1. The remaining perchlorate oxygen atoms do not participate in such close approaches.

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