SYNTHESIS, CRYSTAL-STRUCTURE, MAGNETIC-SUSCEPTIBILITY, AND SINGLE-CRYSTAL EPR STUDIES OF BIS(DIAZAFLUORENONE)DICHLOROCOPPER(II) - A NOVEL CU(NN)2X2 SYSTEM WITH AN UNUSUAL DISTORTION

The crystal structure of Cu(dafone)2Cl2 (dafone = 4,5-diazafluoren-9-one) was determined (monoclinic, space group P2, In with a = 6.5911 (6) angstrom, b = 13.0712 (5) angstrom, c = 11.4813 (9) angstrom, beta = 95.575 (4)-degrees, and Z = 2). This structure represents the first crystallographic example in a family of Cu(NN)2X2 chromophores (NN = 2,2'-bipyridine, 1,10-phenanthroline, or bis(2-pyridyl)amine, and X is an anion) that has retained its octahedral coordination through trans ligation, in spite of the steric effects. The room-temperature magnetic moment is 1.74-mu(B), and it shows little variation down to 5 K. An exchange-averaged EPR spectrum is observed at X-band frequency while the analysis of line shape at Q-band frequency gave a value of \J\ = 0.005 (3) cm-1. The solid complex has electronic spectral bands at 14.29 kK and 16.95 kK, The molecular g tensor with g(x) = 2.070, g(y) = 2.066, g(z) = 2.206 corresponds to a \x2 - y2] ground state.