THE CRYSTAL AND MOLECULAR STRUCTURES OF 2,3-DIHYDRO-5,6-DIPHENYLPYRAZINE AND ITS COMPLEX WITH SILVER NITRATE

The crystal and molecular structures of 2,3-dihydro-5,6-dipenylpyrazine (C16H14N2), and its complex with silver nitrate AgNO4(C16H14N2)(2) were determined by CAD(4) single crystal diffractometer, using graphite monochromated Mo-Ka radiation. The crystallographic data are, (1) C16H14N2, monoclinic, P2(1)/n, a = 5, 685(3), b = 7.928(1), alpha = 27.261(8) angstrom, beta = 95.02(6)degrees, V = 1228.7 angstrom(3), z = 4, (2) AgNO3 (C16H14N2)(2), monoclinic, A(2), a = 5.655(3), b = 7.791(2), c = 30.502(5) angstrom, beta = 94.90 (2)degrees, V = 1335.5 angstrom(3), z = 2. The structure of (1) was solved by direct method and (2) by heavy atom method. The full matrix least squares refinement for (1) with isotripic thermal parameters for H atoms and anisotropic for the others was converged at R = 0.031, and R-W = 0.033, the refinement for (2), excluding H atoms, at R = 0.033 and R-W = 0.028. In the structure of C16H14N2, bond lengths and angles are not unexpected, and dihedral angles between pyrazine ring plane and each plane of the two phenyls are 151.9 degrees and 136.7 degrees respectively. In the structure of AgNO3 (C16H14N2)(2), the Ag atom is positioned on a 2-fold axis, and coordinated by two N and four O atoms to form a severely distorted octahedron, the distance Ag(1)-O(1) is 2.828, Ag(1)-(2) 2.520, and Ag(1)-N(31)2.399 angstrom. The confirmation of the C16H14N2 molecule in the complex was compared with that of the free ligand.