Structural and magnetic studies of dimeric copper(II) 2,2-diphenylpropanoato and triphenylacetato complexes with oxygen-donor ligands. The cage geometry of dimeric alpha-phenyl substituted copper(II) carboxylates

The syntheses, structures, and magnetic properties of copper(II) carboxylates with bridging alpha-phenyl substituted carboxylato ligands and unidentate oxygen-donor ligands are reported: Cu-2(O(2)CCPh(2)Me)(4)(acetone)(2) (1), triclinic <P(1)over bar>, a=15.441(4), b=15.602(4), c=12.790(2) Angstrom, alpha=106.52(2), beta=92.11(2), gamma=96.38(2)degrees, V=2928(1) Angstrom(3), Z=2, -2J=352 cm(-1); [Cu-2(O(2)CCPh(2)Me)(4)(H2O)(2)]. H2O (2), triclinic <P(1)over bar>, a=13.895(2), b=14.717(2), c=7.318(1) Angstrom, alpha=95.67(1), beta=101.71(1), gamma=68.12(1)degrees, V-1359.3(4)Angstrom(3), Z=1, -2J=344 cm(-1); [Cu-2(O(2)CCPh(2)Me)(4)(EtOH)(2)]. EtOh (3), monoclinic P2(1)/c, a=26.927(5), b=9.152(3), c=26.881(5) Angstrom, beta=116.02(1)degrees, V=6003(2) Angstrom(3), Z=4, -2J=347 cm-1; [Cu-2(O(2)CCPh(3))(4)(Ph(3)CCO(2)H)(2)]. 4H(2)O (5a), tetragonal <I(4)over bar>, 1=18.451(6), c=10.703(7) Angstrom, V=3643(3) Angstrom(3), Z=2; [Cu-2(O(2)CCPh(3))(4)(H2O)(2)]. 2H(2)O (5b), tetragonal <I(4)over bar>, a=18.224(2), c=10.776(5) Angstrom, V=3578(1) Angstrom(3), Z=2, -2J=292 cm(-1); and Cu-2(O(2)CSiPh(3))(4)(EtOh)(2) (6), monoclinic C2/c, a=21.811(3), b=17.366(3), c=21.221(4) Angstrom, beta=91.19(1)degrees, V=8036(2) Angstrom(3), Z=4, -2J=1193 cm(-1). The factors which influence the cage and coordination sphere geometry in dimeric alpha-phenyl substituted copper(II) carboxylates are discussed based on the above structures and the reported structures with unidentate nitrogen- and oxygen-donor ligands. In 4 and 5, intramolecular steric effects between the bulky triphenylacetato ligands result in a considerable distrotion of the cage geometry. The distrotion of the coordination sphere geometry around copper(II) in the complexes from square pyramidal toward trigonal bipyramidal reduces the spin-exchange interaction.