J. Pinkas et al., ORIGIN OF DIFFERENT COORDINATION POLYHEDRA FOR CU[CF3C(O)CHC(O)CF3](2)L(L=H2O, NH3), Inorganic chemistry, 34(21), 1995, pp. 5314-5318
Cu(hfacac)(2)(NH3) (hfacac = CF3C(O)CHC(O)CF3-) is shown to have a tri
gonal-bipyramidal structure with Cu-O (axial) = 1.945(3) Angstrom, Cu-
O (equatorial) = 2.075(3) Angstrom and Cu-N = 1.933(6) Angstrom. This
contrasts with the square-pyramidal structure of Cu(hfacac)(2)(H2O), w
hich has a long (2.204(3) Angstrom) Cu-OH2 bond. The ammine complex re
tains its NH3 ligand upon vacuum sublimation, while the H2O complex lo
ses water. The difference in coordination geometry and Cu-L distance (
L = H2O, NH3) is traced to minimizing a antibonding interactions with
the stronger ligand L, which, by the criterion of 10Dq, is NH3. Crysta
l data (-67 degrees C): a = 20.594(6) Angstrom, b = 8.881(2) Angstrom,
c = 8.619(2) Angstrom, beta = 104.49(1)degrees with Z = 4 in space gr
oup C2/c.