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Interaction of AlkylHalides with the Di -ironoctacarbonylate Anion : the Crystal Structures of the Tetraethylammonium Salts of the p-Acetyl-C1(Fel, Fe2)O(Fe1, Fe3) aonacarbonyl-friangulo-triferrate and p2-Carbonylnonacarbonyl -p3 -2,4dioxapentylidyne -triangulotriferrate Anions

1-5-1 Chofugaoka CHOFU-CITY TOKYO 182-8585 JAPAN Some Cu(II) transition complexes, coordinated by pyrimidines or related compounds which have meta-coordination positions, showed magnetic interactions (Ishida and Nogami 1997). Crystal structure analyses revealed that the one-dimensional polymer structures bridged via meta-N ligands on the axial-equatorial position are essential for the ferromagnetic properties (M. Yasui et al., 2001). In the case of [Cu(hfac) (qz)] , where qz=quinazoline and hfac=1,1,1,5,5,5-hexafluoropentane-2,4-dionate, the coordination mode of the meta-N atoms is an axial-axial at room temperature. The bond lengths around the Cu1 atom are significantly changed at 120 K, that is, N1-Cu1 2.182 to 2.043 and O1-Cu1 2.070 to 2.189 Å, while N2-Cu2 and O2-Cu2 remain unchanged. Thus the coordination mode is an axial-equatorial at 120 K. No evidence of the first-order transitions was observed from DSC and the lattice constants. The expansion coefficient of the lattice volume, however, changed at about 210 K. This corresponds that the structural transition is a secondorder. The detailed temperature-dependent structure analyses showed that Cu1-O1 and Cu1-N1 lengths changed gradually and the coordination modes were changed at 255 K. The analysis of the rigid-molecular vibration of the quinazoline moiety revealed that these gradual changes ascribed to the molecular rotation of the quinazoline ring.