Crystal structure of 8-ethoxy-3-(4-nitrophenyl)-2H-chromen-2-one

In the title compound, C17H13NO5, the coumarin ring system is essentially planar (r.m.s. deviation = 0.008 angstrom). The nitrophenyl ring makes a dihedral angle of 25.27 (9)degrees with the coumarin ring plane. The nitro group is almost coplanar with the phenyl ring to which it is attached, making a dihedral angle of 4.3 (3)degrees. The ethoxy group is inclined to the coumarin ring plane by 4.1 (2)degrees. Electron delocalization was found at the short bridging C-C bond with a bond length of 1.354 (2) angstrom. In the crystal, molecules are linked via C-H center dot center dot center dot O hydrogen bonds, forming sheets in the bc plane. The sheets are linked via pi-pi stacking centroid-centroid distances = 3.5688 (13) and 3.7514 (13) angstrom], forming a three-dimensional structure

Measurement of the two-jet differential cross section in p(p)over-bar collisions at root s=1800 GeV

A measurement is presented of the two-jet differential cross section d(3)sigma /dE(T)d eta (1)d eta (2) at center of mass energy roots = 1800 GeV in p (p) over bar collisions. The results are based on an integrated luminosity of 86 pb(-1) collected during 1994 to 1995 by the CDF Collaboration at the Fermilab Tevatron collider. The differential cross section is measured as a function of the transverse energy E-T of a jet in the pseudorapidity region 0.1(1)\<0.7 for four different pseudorapidity bins of a second jet restricted to 0.1<\ eta (2) \<3.0. The results are compared with next-to-leading order QCD calculations determined using the CTEQ4 and MRST sets of parton distribution functions. None of the sets ex.amined in this analysis provides a good description of the data