Tetrakisimidazolecopper(II) iodide; a non-chelated cupric iodide complex

Substitution of copper(2+) in the reaction center diquinone electron acceptor complex of Rhodobacter sphaeroides: determination of the metal-ligand coordination

“…We estimate the departure from a coplanar array of four nitrogen atoms to be less than a = 15°, on the basis of a comparison of the gt and As values with the values observed for 65Cu(ImH)4HP04 in frozen aqueous solutions (Table II). This is known from X-ray diffraction studies of the diiodide and the sulfate analogues to be essentially square planar in the solid state (Aktar et al, 1968;Fransson & Lundberg, 1972). The correlation between a and both g and A is also illustrated by the Cu(II) tropocoronands given in Table II (Davis et al, 1985).…”

“…The difference in the parallel vs. perpendicular nitrogen hyperfine splittings for ligands coordinated to square-planar Cu(II) complexes, (||) -(±), is well understood to be due to the dipolar contribution to the hyperfine interactions (Symons, 1978; Rist & Hyde, 1970). The lower limit estimate for the Cu-N distance of 135 pm based on this dipolar part can be compared with the average Cu-N distance of 200 pm observed in the tetragonal complex Cu(ImH)4I2 (Aktar et al, 1968) and 201 pm in Cu(ImH)4S04 by X-ray diffraction (Fransson & Lundberg, 1972). The Fe-N distances in the Rps.…”

Preparation and structure of chloro-copper(II) complexes of 7-azaindole

“…Interestingly, even when the reaction was carried out with four-to six-fold excess of ligand, the same CuCl,(Haza), compound was the only complex isolated. We were unable to obtain [Cu(Haza),]Cl,, even though such [CuL,]X, compounds are known with imidazoles (26)(27)(28)(29)(30) and pyridines (3 1 ligands are all formally neutral and coordinated to copper via N7. The square planes, roughly perpendicular to the twofold axis, are bridged by chloride ions lying on the same axis, which complete an overall (4 + 2)-coordination about the metal.…”

Interactions of histidine and other imidazole derivatives with transition metal ions in chemical and biological systems

“…A crystal structure determination Cu(lm)4l2 has been reported in preliminary form. 54 The coordinating imidazole nitrogens occupy essentially square-planar positions, the rings being oriented approximately perpendicularly to the plane of the coordinating nitrogen atoms. The iodides occupy relatively distant positions on a distorted octahedra.…”