CONFORMATIONAL STUDIES OF MIXED-LIGAND COPPER(II) CHELATES - CRYSTAL AND MOLECULAR-STRUCTURE OF AMINOETHANE)(1-PHENYL-1,3-BUTANEDIONATO)COPPER(II) PERCHLORATE

The IR and ligand field spectra and the structure of the mixed-ligand compound thyl-1,2-diaminoethane(1-phenyl-1,3-butanedionato) (perchlora to)copper(II)]), [Cu(dmeen)bzac(OClO3)], are reported. The structure w as determined by single crystal X-ray diffraction analysis (triclinic, space group P (1) over bar, a = 8.581(6), b = 9.669(6), c = 12.664(6) Angstrom, alpha = 103.32(6), beta = 103.33(6), gamma = 91.43(6)degree s, Z = 2, R = 0.0628, R(w) = 0.1607). The structure is square pyramida l with the apical position occupied by one oxygen of the tetrahedral p erchlorato group (distance from copper 2.452(5) Angstrom). The plane o f the phenyl ring is tilted forming an angle of 16.72(14)degrees with the plane of the beta-dionato moiety. The nitrogenous base adopts the gauche conformation with torsional angle of 108.72(14)degrees. The eth yl group is cis oriented relative to the phenyl group, occupying the e quatorial position with the vector of the carbon-nitrogen bond forming an angle of 143.9(3)degrees with the CuNN plane. The interactions of the adjacent axial hydrogen with an oxygen of the perchlorato group re sult in hydrogen bond formation. The IR spectra reveal that in the sol id state the Br- or Cl- displace easily the ClO4- group. The shifts in the ligand field spectra indicate that polar solvents participate in donor-acceptor interactions with the metal centre along an axis perpen dicular to the CuN2O2 plane.