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Two kinds of Three-dimensional Quantitative Structure-activity Relationship (3D-QSAR) methods, comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA), were applied to analyze the structure-activity relationship of a series of 63 butenolide ETA selective antagonists with respect to their inhibition against human ETA receptor. The CoMFA and CoMSIA models were developed for the conceivable alignment of the molecules based on a template structure from the crystallized data. The statistical results from the initial orientation of the aligned molecules show that the 3D-QSAR model from CoMFA (q2 = 0.543) is obviously superior to that from the conventional CoMSIA (q2 = 0.407). In order to refine the model, all-space search (ASS) was applied to minimize the field sampling process. By rotating and translating the molecular aggregate within the grid systematically, all the possible samplings of the molecular fields were tested and subsequently the one with the highest q2 was picked out. The comparison of the sensitivity of CoMFA and CoMSIA to different space orientation shows that the CoMFA q2 values are more sensitive to the translations and rotations of the aligned molecules with respect to the lattice than those of CoMSIA. The best CoMFA model from ASS was further refined by the region focused technique. The high quality of the best model is indicated by the high cross-validated correlation and the prediction on the external test set. The CoMFA coefficient contour plots identify several key features that explain the wide range of activities, which may help us to design new effective ETA selective antagonists.

The black crystal of (NH4)[Mo2(S2)6]* 8/3 H2O belongs to the orthorhombic system, space group D32-P22121, with a = 12.064(6), b = 12.534(4), c = 19.558(9)A, V =2957(3)A3, Z = 4 and Dc = 2.23g.cm−3. The intensity data were collected on a Syntex R3 four-circle diffractometer. The structure was solved by Patterson method and direct method, the light atoms (except H atoms) were obtained from ΔF syntheses. The structure was refined by least-squares with anisotropic thermal parameters. The values of R and Rw were 0.092 and 0.072 respectively. The crystal structure contains discrete dimeric cluster [Mo2(S2)6]2− ions, NH4+ cations and H2O molecules. There are two crystallographically independent [Mo2S2)6]2− ions in the crystal, one locates on general position [Figure 1(a)], the other locates on two-fold axis [Figure 1(b)]. It contains one and a half [Mo2S2)6]2− ions in an asymmetric unit. In [Mo2S2)6]2− each Mo is coordinated side on by four S22− groups in a distorted dodecahedral arrangement, two of which are bridging and the other two are terminal. The MoS bond length is 2.441 A (mean), and SS is 2.049 A (mean). The MoMo distance is 2.784 A (mean), which is to be regarded as a single bond length. The formal oxidation state of Mo is five, it is probably a mixed valence MoIVMoVI, and so shows a remarkable deep colour.

The crystal of tetrahydrothiazole-2-thione (TTT) belongs to monoclinic system. Space group P21/n. There are eight molecules in an unit cell with parameters a = 13.844(7)A, b = 5.614 (2)A, c = 13.516 (7)A, β=95.08 (5)°, V =1046.3 (9)A3 The three dimensional intensity data were obtained on a Syntex R3 four-circle diffractometer, and the number of the independent diffractions amounted to 1906. The structure was solved by direct method and refined by block-diagonal least-squares method. The final R is 0.082. In crystal, the molecular structure is between 1 and 2 in which S(1), S(2), N and C(1) are coplanar with conjugation. We use CNDO/2 programmes written by ourselves on Eclipse computer to compute the electronic energies, molecular total energies, dipole moments, the charge densities and net charges of each atom of TTT and its N-benzoylated derivative. The color of the acylated TTT and its properties for aminolysis are discussed.

Reaction of N-cinnamylidenyl-m-4-xylidine (tricarbonyl) iron (1) with phenyllithium and p-chlorophenyllithium at low temperature, and subsequent alkylation of the resulting adducts with Et3OBF4 in CH2Cl2 at −60°C gave two novel zwitter-ion iron complexes with the compositions of C19H22 N(CO)3 FeC6H5(2) and C19H22N(CO)FeC6H4Cl (3), respectively. The complex 2 crystallizes in the monoclinic system, space group P21/n with a = 10.624(3), b = 25.155(6), c = 19.375(9)A, β = 101.1 (3)°, V= 5042.2A3, Z=8, Dc = 1.27g/cm3. The structure of 2 has been solved by direct method and refined by block-matrix least-squares method to give the final R of 0.071.